Journal articles: 'Photo-sensitive Hydrogel'

1

Shang, Jiaojiao, and Patrick Theato. "Smart composite hydrogel with pH-, ionic strength- and temperature-induced actuation." Soft Matter 14, no. 41 (2018): 8401–7. http://dx.doi.org/10.1039/c8sm01728j.

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A facile and versatile photo-patterning method to fabricate “smart” hydrogels with defined lateral and vertical inhomogeneity of hydrogel composition and dimensions has been developed via generating programmable composite hydrogels and bilayer hydrogels based on thermal and ionic strength-responsive poly(N-isopropylacrylamide) and pH-sensitive poly(acrylic acid) hydrogels.

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Kargar-Estahbanaty, Arash, Mostafa Baghani, and Nasser Arbabi. "Developing an analytical solution for photo-sensitive hydrogel bilayers." Journal of Intelligent Material Systems and Structures 29, no. 9 (January 30, 2018): 1953–63. http://dx.doi.org/10.1177/1045389x18754353.

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In this article, a new conceptual design of light-sensitive switches made of a soft bilayer is introduced. The bilayer structure consists of a photothermal-sensitive hydrogel strip attached to another neutral incompressible elastomeric layer. The bilayer is assumed to be initially flat under a uniform light irradiation. Decreasing the light intensity causes the bilayer to bend due to the inhomogeneous swelling of hydrogel layer and results in the switch actuation. To enlighten the actuation mechanism and investigate the influence of various parameters on the switch’s photomechanical response, an analytical method is developed to study the bilayer deformation due to the light-intensity variation under plane-strain condition. Additionally, the finite element analysis of the bilayer is conducted, implementing the relevant constitutive model into a finite element code. The deformation and stress inside the layers are studied both analytically and numerically for several cases. The numerical results verify the accuracy of the presented analytical method in this work. The influence of various material and geometrical parameters including each layer’s modulus, the thickness ratio of the layers, and the aspect ratio of the bilayer is investigated. The analytical method is found to be useful for proper design of the light-sensitive hydrogel-based switches.

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Chen, Xiao, Zhixin Zhan, Qimin Liu, and Tao Wu. "Modeling the response characteristics of photo-sensitive hydrogel electrolytes in Hofmeister salt solution for the development of smart energy storage devices." Sustainable Energy & Fuels 4, no. 12 (2020): 6112–24. http://dx.doi.org/10.1039/d0se00639d.

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Wu, Te Hsing, Ko Shao Chen, and Lie Hang Shen. "The Surface Modification and Characteristics of Useful Expanded PTFE Composites by Photo-Radiation Methods." Advanced Materials Research 690-693 (May 2013): 1636–40. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1636.

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In this study, We immobilized hydrogel material onto expanded polytetrafluoroethylene (ePTFE) film and used as an functional biomaterial. The material is a film containing titanium oxide onto polymer sheet. The hydrogel film is hydrophilic, bacterial inactivated and bio-compatible. In order to improve the ePTFE film biocompatibility, the cold plasma or γ-ray technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by radiation photo-grafting. The characteristics of the material surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition procedure. Due to the hydrophilicity of poly (N-isopropylacrylamide), so the contact angle of water on the ePTFE-g-NIPAAm almost approached to 0°. This thermal sensitive ePTFE hydrogels can be applied to artificial guiding tube and wound dressing material.

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He, Ming, Baoqin Han, Zhiwen Jiang, Yan Yang, Yanfei Peng, and Wanshun Liu. "Synthesis of a chitosan-based photo-sensitive hydrogel and its biocompatibility and biodegradability." Carbohydrate Polymers 166 (June 2017): 228–35. http://dx.doi.org/10.1016/j.carbpol.2017.02.072.

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Zhang, Shu Di, Yu Chun Zhai, and Zhen Fang Zhang. "Study on Polyvinly-Alcohol(PVA)/ Iron Oxide Black(Fe₃O₄) and Polyvinly-Alcohol(PVA)/ Iron Oxide Red(Fe₂O₃) Magnetic Sensitive Hydrogel." Advanced Materials Research 287-290 (July 2011): 2032–35. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.2032.

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Iron oxide black and iron oxide red magnetic sensitive to polyvinly-alcohol hydrogel has been fabricated using physical cross-linking method. The mechanical properties and swelling characteristics have been studied for different content, magnetic sensibility were tested using the vibration sample magnetometer, experiment results show that iron oxide red hydrogel has better mechanical properties, Percentage of swelling and loss rate of water of the polyvinly-alcohol hydrogel decrease with the increasing of the magnetic particles content, the change tendency is very like, cross-linking is increased with performance the swelling performance decreasing; PVA and Fe3O4 has good response from the SEM photo and IR spectrogram; its magnetic properties is better.

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Li, Bing, Dapeng Li, Yanni Yang, Lu Zhang, Ke Xu, and Jiping Wang. "Study of thermal-sensitive alginate-Ca2+/poly(N-isopropylacrylamide) hydrogels supported by cotton fabric for wound dressing applications." Textile Research Journal 89, no. 5 (February 7, 2018): 801–13. http://dx.doi.org/10.1177/0040517518755790.

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In this study, direct deposition, 1,2,3,4-butanetetracarboxylic acid (BTCA) crosslinking, chelating and ultraviolet (UV) photo-grafting methods were employed to bond alginate-Ca2+/poly( N-isopropylacrylamide) (PNIPAAm) interpenetrating network hydrogel onto cotton fabric surface for wound dressing applications. Infrared spectroscopy confirmed the presence of alginate-Ca2+/PNIPAAm hydrogels on the cotton fabrics. Scanning electron microscopy was used to investigate surface and cross-section morphologies. Differential scanning calorimetry and three-dimensional video microscopy indicated that fabric-supported hydrogels maintained the thermal-sensitive property with a lower critical solution temperature (LCST) of around 34–35℃. The results of water vapor permeation revealed that the water vapor transmission rate at 37℃ was significantly higher than that at 25℃ for the shrink and collapse of the hydrogels above the LCST. Moreover, the breaking stress of the fabric-supported hydrogels was similar to that of the original cotton fabrics, but much larger than the hydrogels by themselves. The UV photo-grafting provided the strongest peel strength, followed by the BTCA crosslinking, the chelating and the direct deposition method. The cotton fabric-supported alginate-Ca2+/PNIPAAm hydrogels were stiffer than the original cotton fabric due to the high glass transition temperature of PNIPAAm (about 140℃). The in vitro drug release experiment confirmed that the cumulative release amount was much higher at around 37℃ (above the LCST) than at 25℃ (below the LCST). This showed that the fabric-supported thermal-sensitive hydrogels had functions of keeping the wound area breathable and comfortable, and provided controlled drug release with good mechanical properties, indicating a great potential and significance for wound dressing applications.

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Schmidt, Ulrike, Margarita Guenther, and Gerald Gerlach. "Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications." Current Directions in Biomedical Engineering 2, no. 1 (September 1, 2016): 117–21. http://dx.doi.org/10.1515/cdbme-2016-0029.

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AbstractMany conventional analysis techniques to detect chemical or biological species are able to achieve a high detection sensitivity, however, they are equipment- or time-expensive due to a multi-step procedure. In this work we describe sensor concepts using piezoresistive pressure sensor chips with integrated analyte-sensitive hydrogels, that enable inexpensive and robust biochemical sensors which are miniaturizable and in-line capable. Biocompatible hydrogels were developed and tested for pH- and glucose-monitoring during the chemical and biochemical processes. For that, monomer mixtures based on hydroxypropyl methacrylate HPMA, 2-(dimethylamino)ethyl methacrylate DMAEMA, tetraethylene glycol dimethacrylate TEGDMA and ethylene glycol EG were photo-polymerized. By means of carbodiimide chemistry, glucose oxidase was bound to the pH-sensitive HPMA/DMAEMA/TEGDMA/EG hydrogel squares causing the glucose-sensitivity. The crosslinked hydrogels were integrated in piezoresistive pressure sensors of different designs. pH- and glucose-depending reversible gel swelling processes were observed by means of the output voltage of dip sensors and of a novel implantable flexible sensor set-up. Due to its biocompatible components, the latter could be used inside the human body monitoring physiological blood values, for example glucose.

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Chen, Ko Shao, Su Chen Chen, Yi Chun Yeh, Wei Cheng Lien, Hong Ru Lin, and Jen Ming Yang. "The Study of Immobilization Thermal-Sensitive Hydrogel onto ePTFE Film Use the Cold Plasma and Photo-Grafting Technique." Advanced Materials Research 15-17 (February 2006): 187–92. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.187.

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Expanded polytetrafluoroethylene (ePTFE) is a bioinert material. To improve the ePTFE film biocompatibility, the cold plasma technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by photo-grafting. The characteristics of the surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition treatment. Due to the hydrophilicity of poly(N-isopropylacrylamide), the contact angle of water on the ePTFE-g-NIPAAm approached to 0°.

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10

Liu, Junyu, Yu Xiao, Xiangyu Wang, Lixun Huang, Yu Chen, and Chongyun Bao. "Glucose-sensitive delivery of metronidazole by using a photo-crosslinked chitosan hydrogel film to inhibit Porphyromonas gingivalis proliferation." International Journal of Biological Macromolecules 122 (February 2019): 19–28. http://dx.doi.org/10.1016/j.ijbiomac.2018.09.202.

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11

Kargar-Estahbanaty, Arash, Mostafa Baghani, Hamid Shahsavari, and Ghader Faraji. "A Combined Analytical–Numerical Investigation on Photosensitive Hydrogel Micro-Valves." International Journal of Applied Mechanics 09, no. 07 (October 2017): 1750103. http://dx.doi.org/10.1142/s1758825117501034.

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In this paper, employing photo-thermal sensitive (PTS) hydrogels, a photosensitive bio-compatible micro-valve is investigated. In this regard, the energy representation and governing equations of PTS hydrogels are described. Two benchmark problems common in micro-fluidic designs are solved using the presented theory, and the deformation and stress distributions are calculated. The theory is implemented into a finite element (FE) framework by developing a user-defined subroutine. To properly validate the FE model, the FE results are compared with the proposed analytical results. The confirmed numerical method is then employed to investigate two different realistic micro-valve structures. The constructions are composed of three jacket-pillar structures arranged in two different patterns. In this step, the nonlinear contact between the components of structures and presumptive rigid walls are added to the thermo-mechanical deformation of the photosensitive micro-jackets. The contact length and contact pressure are investigated. By calculating all necessary mechanical parameters, the analysis results can be utilized in the design procedure of a photosensitive micro-valve and pave the way for the industrial production of the next generation micro-fluidic devices.

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Bako, Jozsef, Ferenc Toth, Jozsef Gall, Renato Kovacs, Attila Csík, Istvan Varga, Anton Sculean, Romana Zelko, and Csaba Hegedus. "Combined Release of Antiseptic and Antibiotic Drugs from Visible Light Polymerized Biodegradable Nanocomposite Hydrogels for Periodontitis Treatment." Pharmaceutics 14, no. 5 (April 28, 2022): 957. http://dx.doi.org/10.3390/pharmaceutics14050957.

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The in situ application of the combination of different types of drugs revolutionized the area of periodontal therapy. The purpose of this study was to develop nanocomposite hydrogel (NCHG) as a pH-sensitive drug delivery system. To achieve local applicability of the NCHG in dental practice, routinely used blue-light photopolymerization was chosen for preparation. The setting time was 60 s, which resulted in stable hydrogel structures. Universal Britton–Robinson buffer solutions were used to investigate the effect of pH in the range 4–12 on the release of drugs that can be used in the periodontal pocket. Metronidazole was released from the NCHGs within 12 h, but chlorhexidine showed a much longer elution time with strong pH dependence, which lasted more than 7 days as it was corroborated by the bactericidal effect. The biocompatibility of the NCHGs was proven by Alamar-blue test and the effectiveness of drug release in the acidic medium was also demonstrated. This fast photo-polymerizable NCHG can help to establish a locally applicable combined drug delivery system which can be loaded with the required amount of medicines and can reduce the side effects of the systemic use of drugs that have to be used in high doses to reach an ideal concentration locally.

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Tartivel, Lucile, Marc Behl, Michael Schroeter, and Andreas Lendlein. "ABA triblock copolymer based hydrogels with thermo-sensitivity for biomedical applications." MRS Proceedings 1569 (2013): 135–40. http://dx.doi.org/10.1557/opl.2013.840.

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ABSTRACTOligo(ethylene glycol)-oligo(propylene glycol)-oligo(ethylene glycol) (OEG-OPG-OEG) triblock copolymers are hydrogel forming and extensively investigated in the field of drug release due to their biocompatibility and thermo-sensitivity. Here the synthesis and characterization of OEG-OPG-OEG based polymer networks from methacrylated oligomers by photo-irradiation are reported. Two precursors were selected to have comparable hydrophilicity (80 wt% OEG content) but different molecular weights of Mn = 8400 g·mol-1 and 14600 g·mol-1. The precursor solutions were prepared in concentration 10 to 30 wt%. The resulting polymer networks prepared from high Mn precursors exhibited higher swellability at equilibrium (up to 3400%) and mechanical properties in the range of G’ ∼ 0.1 to 1 kPa at 5 °C compared to networks based on low Mn precursors. A more significant thermo-sensitive behavior in terms of swellability, volumetric contraction and mechanical transition, starting at 30 °C could also be observed for the networks based on high Mn precursors, thus promoting future application in the field of drug release.

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Laurano, Rossella, Monica Boffito, Claudio Cassino, Ludovica Midei, Roberta Pappalardo, Valeria Chiono, and Gianluca Ciardelli. "Thiol-Ene Photo-Click Hydrogels with Tunable Mechanical Properties Resulting from the Exposure of Different -Ene Moieties through a Green Chemistry." Materials 16, no. 5 (February 28, 2023): 2024. http://dx.doi.org/10.3390/ma16052024.

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Temperature and light responsiveness are widely exploited stimuli to tune the physico-chemical properties of double network hydrogels. In this work, new amphiphilic poly(ether urethane)s bearing photo-sensitive moieties (i.e., thiol, acrylate and norbornene functionalities) were engineered by exploiting the versatility of poly(urethane) chemistry and carbodiimide-mediated green functionalization procedures. Polymers were synthesized according to optimized protocols maximizing photo-sensitive group grafting while preserving their functionality (approx. 1.0 × 1019, 2.6 × 1019 and 8.1 × 1017 thiol, acrylate and norbornene groups/gpolymer), and exploited to prepare thermo- and Vis-light-responsive thiol-ene photo-click hydrogels (18% w/v, 1:1 thiol:ene molar ratio). Green light-induced photo-curing allowed the achievement of a much more developed gel state with improved resistance to deformation (ca. 60% increase in critical deformation, γL). Triethanolamine addition as co-initiator to thiol-acrylate hydrogels improved the photo-click reaction (i.e., achievement of a better-developed gel state). Differently, L-tyrosine addition to thiol-norbornene solutions slightly hindered cross-linking, resulting in less developed gels with worse mechanical performances (~62% γL decrease). In their optimized composition, thiol-norbornene formulations resulted in prevalent elastic behavior at lower frequency compared to thiol-acrylate gels due to the formation of purely bio-orthogonal instead of heterogeneous gel networks. Our findings highlight that exploiting the same thiol-ene photo-click chemistry, a fine tuning of the gel properties is possible by reacting specific functional groups.

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Toh, William, Teng Yong Ng, Jianying Hu, and Zishun Liu. "Mechanics of inhomogeneous large deformation of photo-thermal sensitive hydrogels." International Journal of Solids and Structures 51, no. 25-26 (December 2014): 4440–51. http://dx.doi.org/10.1016/j.ijsolstr.2014.09.014.

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Toh, William, Zhiwei Ding, Teng Yong Ng, and Zishun Liu. "Light intensity controlled wrinkling patterns in photo-thermal sensitive hydrogels." Coupled systems mechanics 5, no. 4 (December 25, 2016): 315–27. http://dx.doi.org/10.12989/csm.2016.5.4.315.

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Toh, William, Zhiwei Ding, Teng Yong Ng, and Zishun Liu. "Light intensity controlled wrinkling patterns in photo-thermal sensitive hydrogels." Multiscale and Multiphysics Mechanics 1, no. 1 (January 25, 2016): 87–99. http://dx.doi.org/10.12989/mmm.2016.1.1.087.

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Li, Pan, Jiacheng Zhang, and Chang-Ming Dong. "Photosensitive poly(o-nitrobenzyloxycarbonyl-l-lysine)-b-PEO polypeptide copolymers: synthesis, multiple self-assembly behaviors, and the photo/pH-thermo-sensitive hydrogels." Polymer Chemistry 8, no. 45 (2017): 7033–43. http://dx.doi.org/10.1039/c7py01574g.

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We synthesize a photosensitive poly(o-nitrobenzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol) block copolymer and fabricate three kinds of dual-sensitive (i.e., photo/pH-thermo) polypeptide normal and reverse micellar hydrogels.

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Mazaheri, Hashem, Amir Hossein Namdar, and Amir Ghasemkhani. "A model for inhomogeneous large deformation of photo-thermal sensitive hydrogels." Acta Mechanica 232, no. 8 (May 11, 2021): 2955–72. http://dx.doi.org/10.1007/s00707-021-02991-w.

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Li, Zhangkang, Huiyu Bai, Shengwen Zhang, Wei Wang, Piming Ma, and Weifu Dong. "DN strategy constructed photo-crosslinked PVA/CNC/P(NIPPAm-co-AA) hydrogels with temperature-sensitive and pH-sensitive properties." New Journal of Chemistry 42, no. 16 (2018): 13453–60. http://dx.doi.org/10.1039/c8nj02132e.

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The surface and cross-section morphologies of PVA/CNC/P(NIPPAm-co-AA) hydrogels exhibited double-network (DN) and uniform network structures due to the introduction of PNIPAAm and PAA through the photo-crosslinking technology.

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Matsukuma, Daisuke, Kazuya Yamamoto, and Takao Aoyagi. "Novel Photo-Reactive Acrylamide-Based Copolymers Instantly Gave the Sensitive Stimuli-Responsive Hydrogels." Journal of Photopolymer Science and Technology 19, no. 4 (2006): 445–49. http://dx.doi.org/10.2494/photopolymer.19.445.

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Lee, Jun Bae, Jun Jin Yoon, Doo Sung Lee, and Tae Gwan Park. "Photo-crosslinkable, thermo-sensitive and biodegradable Pluronic hydrogels for sustained release of protein." Journal of Biomaterials Science, Polymer Edition 15, no. 12 (January 2004): 1571–83. http://dx.doi.org/10.1163/1568562042459751.

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23

Niu, Fang, Jin Zhai, Lei Jiang, and Wei-Guo Song. "Light induced activity switch in interfacial hydrogen-bond catalysis with photo sensitive metal oxides." Chemical Communications, no. 31 (2009): 4738. http://dx.doi.org/10.1039/b908834b.

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Ren, Panpan, Dawei Zhang, Chaofang Dong, and Xiaogang Li. "Preparation and evaluation of intelligent corrosion inhibitor based on photo-crosslinked pH-sensitive hydrogels." Materials Letters 160 (December 2015): 480–83. http://dx.doi.org/10.1016/j.matlet.2015.08.005.

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Torgersen, Jan, Aleksandr Ovsianikov, Vladimir Mironov, Niklas Pucher, Xiaohua Qin, Zhiquan Li, Klaus Cicha, et al. "Photo-sensitive hydrogels for three-dimensional laser microfabrication in the presence of whole organisms." Journal of Biomedical Optics 17, no. 10 (October 15, 2012): 1. http://dx.doi.org/10.1117/1.jbo.17.10.105008.

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Aparicio, Francisca, Juan Pablo Escalada, Eduardo De Gerónimo, Virginia C. Aparicio, Fernando S. García Einschlag, Giuliana Magnacca, Luciano Carlos, and Daniel O. Mártire. "Carbamazepine Degradation Mediated by Light in the Presence of Humic Substances-Coated Magnetite Nanoparticles." Nanomaterials 9, no. 10 (September 26, 2019): 1379. http://dx.doi.org/10.3390/nano9101379.

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The use of iron-based nanomaterials for environmental remediation processes has recently received considerable attention. Here, we employed core-shell magnetite-humic acids nanoparticles as a heterogeneous photosensitizer and iron source in photo-Fenton reaction for the degradation of the psychiatric drug carbamazepine (CBZ). CBZ showed low photodegradation rates in the presence of the magnetic nanoparticles, whereas the addition of hydrogen peroxide at pH = 3 to the system drastically increased the abatement of the contaminant. The measured Fe2+ and Fe3+ profiles point to the generation of Fe3+ at the surface of the nanoparticles, indicating a heterogeneous oxidation of the contaminant mediated by hydroxyl radicals. Products with a higher transformation degree were observed in the photo-Fenton procedure and support the attack of the HO• radical on the CBZ molecule. Promising results encourage the use of the nanoparticles as efficient iron sources with enhanced magnet-sensitive properties, suitable for applications in photo-Fenton treatments for the purification of wastewater.

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Yin, Ruixue, Kemin Wang, Jing Han, and Jun Nie. "Photo-crosslinked glucose-sensitive hydrogels based on methacrylate modified dextran–concanavalin A and PEG dimethacrylate." Carbohydrate Polymers 82, no. 2 (September 2010): 412–18. http://dx.doi.org/10.1016/j.carbpol.2010.04.075.

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Hashtroudi, Hanie, Aimin Yu, Saulius Juodkazis, and Mahnaz Shafiei. "Ultra-Sensitive Photo-Induced Hydrogen Gas Sensor Based on Two-Dimensional CeO2-Pd-PDA/rGO Heterojunction Nanocomposite." Nanomaterials 12, no. 10 (May 10, 2022): 1628. http://dx.doi.org/10.3390/nano12101628.

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A two-dimensional (2D) CeO2-Pd-PDA/rGO heterojunction nanocomposite has been synthesised via an environmentally friendly, energy efficient, and facile wet chemical procedure and examined for hydrogen (H2) gas sensing application for the first time. The H2 gas sensing performance of the developed conductometric sensor has been extensively investigated under different operational conditions, including working temperature up to 200 °C, UV illumination, H2 concentrations from 50–6000 ppm, and relative humidity up to 30% RH. The developed ceria-based nanocomposite sensor was functional at a relatively low working temperature (100 °C), and its sensing properties were improved under UV illumination (365 nm). The sensor’s response towards 6000 ppm H2 was drastically enhanced in a humid environment (15% RH), from 172% to 416%. Under optimised conditions, this highly sensitive and selective H2 sensor enabled the detection of H2 molecules down to 50 ppm experimentally. The sensing enhancement mechanisms of the developed sensor were explained in detail. The available 4f electrons and oxygen vacancies on the ceria surface make it a promising material for H2 sensing applications. Moreover, based on the material characterisation results, highly reactive oxidant species on the sensor surface formed the electron–hole pairs, facilitated oxygen mobility, and enhanced the H2 sensing performance.

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Sánchez Vergara, María Elena, Lorena Ramírez Vargas, Citlalli Rios, Bertha Molina, and Roberto Salcedo. "Investigation of Structural and Optoelectronic Properties of Organic Semiconductor Film Based on 8-Hydroxyquinoline Zinc." Electronics 10, no. 2 (January 8, 2021): 117. http://dx.doi.org/10.3390/electronics10020117.

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In this work, we investigated an organic semiconductor based on zinc 8-hydroxyquinoline (ZnQ2) and tetracyanoquinodimethane (TCNQ), which can be used as a photoactive layer in organic devices. The semiconductor was optimized by applying density-functional theory (DFT) methods, and four hydrogen bridges were formed between ZnQ2 and TCNQ. Later, thin films of ZnQ2-TCNQ were successfully deposited. The films were structurally and morphologically characterized, and the optical characteristics of the photoactive layer were investigated using ultraviolet–visible spectroscopy and time-dependent density-functional theory (TDDFT) calculations. The comparison and analysis of the experimental and theoretical absorption spectra indicate that the optical bandgap of the photoactive layer is 2.4 eV. Additionally, a flexible photo device was manufactured with the active layer ZnQ2-TCNQ, and its electrical behavior was evaluated under dark and light conditions. The results show a significant change in the behavior of the device when radiation is eliminated; the layer is light sensitive. The electrical resistance in the flexible photo device is associated with the optical behavior of the materials that constitute the active layer.

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Sánchez Vergara, María Elena, Lorena Ramírez Vargas, Citlalli Rios, Bertha Molina, and Roberto Salcedo. "Investigation of Structural and Optoelectronic Properties of Organic Semiconductor Film Based on 8-Hydroxyquinoline Zinc." Electronics 10, no. 2 (January 8, 2021): 117. http://dx.doi.org/10.3390/electronics10020117.

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In this work, we investigated an organic semiconductor based on zinc 8-hydroxyquinoline (ZnQ2) and tetracyanoquinodimethane (TCNQ), which can be used as a photoactive layer in organic devices. The semiconductor was optimized by applying density-functional theory (DFT) methods, and four hydrogen bridges were formed between ZnQ2 and TCNQ. Later, thin films of ZnQ2-TCNQ were successfully deposited. The films were structurally and morphologically characterized, and the optical characteristics of the photoactive layer were investigated using ultraviolet–visible spectroscopy and time-dependent density-functional theory (TDDFT) calculations. The comparison and analysis of the experimental and theoretical absorption spectra indicate that the optical bandgap of the photoactive layer is 2.4 eV. Additionally, a flexible photo device was manufactured with the active layer ZnQ2-TCNQ, and its electrical behavior was evaluated under dark and light conditions. The results show a significant change in the behavior of the device when radiation is eliminated; the layer is light sensitive. The electrical resistance in the flexible photo device is associated with the optical behavior of the materials that constitute the active layer.

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Baik, Kwang Hyeon, Jimin Kim, and Soohwan Jang. "Highly sensitive nonpolar a-plane GaN based hydrogen diode sensor with textured active area using photo-chemical etching." Sensors and Actuators B: Chemical 238 (January 2017): 462–67. http://dx.doi.org/10.1016/j.snb.2016.07.091.

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Nagavi, J. B., and B. M. Gurupadayya. "ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR EVALUATING THE STABILITY PARAMETERS FOR THE SIMULTANEOUS ESTIMATION OF CLOPIDOGREL BISULPHATE AND OMEPRAZOLE USING RP-HPLC." INDIAN DRUGS 53, no. 01 (January 28, 2016): 60–67. http://dx.doi.org/10.53879/id.53.01.10296.

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A simple, sensitive, accurate and specific stability-indicating high-performance liquid chromatographic method was developed and validated for the simultaneous estimation of clopidogrel bisulphate and omeprazole in bulk. Extensive testing of clopidogrel bisulphate and omeprazole in different stress conditions were carried out as per the ICH guidelines Q1A (R2) Clopidogrel bisulphate and omeprazole was exposed to various stress conditions like oxidation, hydrolysis, photolysis and neutral decomposition. Clopidogrel bisulphate, which was found to degrade considerably in acidic and photo conditions, was found to be stable in alkaline and neutral conditions, whereas omeprazole was found to be degrading in alkaline, oxidative and photo conditions, but stable in acidic and neutral condition. Apart from the formation of minor degraded products under accelerated conditions, the drugs were reasonably stable in solid state. A good linear relationship over the concentration range of 50-500μg/mL was shown. Validation of the method was carried out as per the ICH guidelines. The method developed was found to be specific, selective, precise and accurate. Clopidogrel bisulphate showed degradation in 5M hydrochloric acid at 80oC, in 3% hydrogen peroxide for 5min the drug showed around 35% of degradation, when exposed to sunlight for 15 min, forming around 25-30% of degradation products. Omeprazole showed 15-18% degradation in alkaline and photo condition.Statistical analysis shows that the method is reproducible and selective for the estimation of clopidogrel bisulphate and omeprazole in dosage form.

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Chen, Xiao, Hua Li, and K. Y. Lam. "A multiphysics model of photo-sensitive hydrogels in response to light-thermo-pH-salt coupled stimuli for biomedical applications." Bioelectrochemistry 135 (October 2020): 107584. http://dx.doi.org/10.1016/j.bioelechem.2020.107584.

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Wu, Te Hsing, Ko Shao Chen, Su Chen Chen, Yi Chun Yeh, and Lie Hang Shen. "The Biomedical Material of Functional ePTFE Hydrogels by the Cold Plasma Method and Radiation Technique." Advanced Materials Research 47-50 (June 2008): 1427–29. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.1427.

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Expanded polytetrafluoroethylene (ePTFE) is a bioinert material. It has the superior properties of thermal and chemical stabilities, low surface energy and high resistivity, so it was applied in many biomedical fields. In order to improve the ePTFE film biocompatibility, the cold plasma technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by photo-grafting. The characteristics of the material surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition procedure. Due to the hydrophilicity of poly(N-isopropylacrylamide), so the contact angle of water on the ePTFE-g-NIPAAm almost approached to 0°. And we obtained the thermal-sensitive ePTFE hydrogels.

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Cho, Young Il, Shinyoung Park, Seo Young Jeong, and Hyuk Sang Yoo. "In vivo and in vitro anti-cancer activity of thermo-sensitive and photo-crosslinkable doxorubicin hydrogels composed of chitosan–doxorubicin conjugates." European Journal of Pharmaceutics and Biopharmaceutics 73, no. 1 (September 2009): 59–65. http://dx.doi.org/10.1016/j.ejpb.2009.04.010.

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Lee, Alpha A., Jason C. S. Lau, Hannah J. Hogben, Till Biskup, Daniel R. Kattnig, and P. J. Hore. "Alternative radical pairs for cryptochrome-based magnetoreception." Journal of The Royal Society Interface 11, no. 95 (June 6, 2014): 20131063. http://dx.doi.org/10.1098/rsif.2013.1063.

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There is growing evidence that the remarkable ability of animals, in particular birds, to sense the direction of the Earth's magnetic field relies on magnetically sensitive photochemical reactions of the protein cryptochrome. It is generally assumed that the magnetic field acts on the radical pair [FAD •− TrpH • + ] formed by the transfer of an electron from a group of three tryptophan residues to the photo-excited flavin adenine dinucleotide cofactor within the protein. Here, we examine the suitability of an [FAD •− Z • ] radical pair as a compass magnetoreceptor, where Z • is a radical in which the electron spin has no hyperfine interactions with magnetic nuclei, such as hydrogen and nitrogen. Quantum spin dynamics simulations of the reactivity of [FAD •− Z • ] show that it is two orders of magnitude more sensitive to the direction of the geomagnetic field than is [FAD •− TrpH • + ] under the same conditions (50 µT magnetic field, 1 µs radical lifetime). The favourable magnetic properties of [FAD •− Z • ] arise from the asymmetric distribution of hyperfine interactions among the two radicals and the near-optimal magnetic properties of the flavin radical. We close by discussing the identity of Z • and possible routes for its formation as part of a spin-correlated radical pair with an FAD radical in cryptochrome.

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Li, Fei, Jie Gao, Haocheng Wu, Yijun Li, Xiwen He, and Langxing Chen. "A Highly Selective and Sensitive Fluorescent Sensor Based on Molecularly Imprinted Polymer-Functionalized Mn-Doped ZnS Quantum Dots for Detection of Roxarsone in Feeds." Nanomaterials 12, no. 17 (August 30, 2022): 2997. http://dx.doi.org/10.3390/nano12172997.

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Roxarsone (ROX) as an organoarsenic feed additive has been widely used in livestock breeding and poultry industry, but ROX can degrade into highly toxic inorganic arsenic species in natural environments to threaten to the environment and human health. Therefore, there is a considerable interest in developing convenient, selective and sensitive methods for the detection of ROX in livestock breeding and poultry industry. In this work, a fluorescent molecularly imprinted polymer (MIPs) probe based on amino-modified Mn-ZnS quantum dots (QDs) has been developed by sol–gel polymerization for specific recognition of ROX. The synthesized MIPs-coated Mn-ZnS QDs (MIPs@Mn-ZnS QDs) have highly selective recognition sites to ROX because there are multi-interactions among the template ROX, functional monomer phenyltrimethoxysilane and the amino-functionalized QDs such as the π–π conjugating effect, hydrogen bonds. Under the optimal conditions, an obvious fluorescence quenching was observed when ROX was added to the solution, and the quenching mechanism could be explained as the photo-induced electron transfer. The MIPs@Mn-ZnS QDs sensor exhibited sensitive response to ROX in the linear range from 3.75 × 10−8 M to 6.25 × 10−7 M (R2 = 0.9985) and the limit of detection down to 4.34 nM. Moreover, the fluorescence probe has been applied to the quantitative detection of ROX in feed samples, and the recovery was in the range of 91.9% to 108.0%. The work demonstrated that the prepared MIPs@Mn-ZnS QDs probe has a good potential for rapid and sensitive determination of ROX in complicated samples.

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Timpmann, Kõu, Margus Rätsep, Liina Kangur, Alexandra Lehtmets, Zheng-Yu Wang-Otomo, and Arvi Freiberg. "Exciton Origin of Color-Tuning in Ca2+-Binding Photosynthetic Bacteria." International Journal of Molecular Sciences 22, no. 14 (July 8, 2021): 7338. http://dx.doi.org/10.3390/ijms22147338.

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Flexible color adaptation to available ecological niches is vital for the photosynthetic organisms to thrive. Hence, most purple bacteria living in the shade of green plants and algae apply bacteriochlorophyll a pigments to harvest near infra-red light around 850–875 nm. Exceptions are some Ca2+-containing species fit to utilize much redder quanta. The physical basis of such anomalous absorbance shift equivalent to ~5.5 kT at ambient temperature remains unsettled so far. Here, by applying several sophisticated spectroscopic techniques, we show that the Ca2+ ions bound to the structure of LH1 core light-harvesting pigment–protein complex significantly increase the couplings between the bacteriochlorophyll pigments. We thus establish the Ca-facilitated enhancement of exciton couplings as the main mechanism of the record spectral red-shift. The changes in specific interactions such as pigment–protein hydrogen bonding, although present, turned out to be secondary in this regard. Apart from solving the two-decade-old conundrum, these results complement the list of physical principles applicable for efficient spectral tuning of photo-sensitive molecular nano-systems, native or synthetic.

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Kurtén, Theo, Noora Hyttinen, Emma Louise D'Ambro, Joel Thornton, and Nønne Lyng Prisle. "Estimating the saturation vapor pressures of isoprene oxidation products C5H12O6 and C5H10O6 using COSMO-RS." Atmospheric Chemistry and Physics 18, no. 23 (December 12, 2018): 17589–600. http://dx.doi.org/10.5194/acp-18-17589-2018.

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Abstract. We have used COSMO-RS (the conductor-like screening model for real solvents), as implemented in the COSMOtherm program, to compute the saturation vapor pressures at 298 K of two photo-oxidation products of isoprene: the dihydroxy dihydroperoxide C5H12O6, and the dihydroperoxy hydroxy aldehyde, C5H10O6. The predicted saturation vapor pressures were significantly higher (by up to a factor of 1000) than recent experimental results, very likely due to the overestimation of the effects of intramolecular hydrogen bonds, which tend to increase saturation vapor pressures by stabilizing molecules in the gas phase relative to the liquid. Modifying the hydrogen bond enthalpy parameter used by COSMOtherm can improve the agreement with experimental results – however the optimal parameter value is likely to be system-specific. Alternatively, vapor pressure predictions can be substantially improved (to within a factor of 5 of the experimental values for the two systems studied here) by selecting only conformers with a minimum number of intramolecular hydrogen bonds. The computed saturation vapor pressures were very sensitive to the details of the conformational sampling approach, with the default scheme implemented in the COSMOconf program proving insufficient for the task, for example by predicting significant differences between enantiomers, which should have identical physical properties. Even after exhaustive conformational sampling, COSMOtherm predicts significant differences in saturation vapor pressures between both structural isomers and diastereomers. For C5H12O6, predicted differences in psat between structural isomers are up to 2 orders of magnitude, and differences between stereoisomers are up to a factor of 20 – though these differences are very likely exaggerated by the overestimation of the effect of intramolecular H-bonds. For C5H10O6, the maximum predicted differences between the three studied structural isomers and their diastereomer pairs are around a factor of 8 and a factor of 2, respectively, when only conformers lacking intramolecular hydrogen bonds are included in the calculations. In future studies of saturation vapor pressures of polyfunctional atmospheric oxidation products using COSMOtherm, we recommend first performing thorough conformational sampling and subsequently selecting conformers with a minimal number of intramolecular H-bonds.

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Burmistrov, V. A., V. V. Aleksandriiskii, I. V. Novikov, and O. I. Koifman. "Mechanisms of Chiral Transfer in Optically Active Dopant – Nematic Liquid Crystal Systems." Liquid Crystals and their Application 20, no. 4 (December 29, 2020): 6–26. http://dx.doi.org/10.18083/lcappl.2020.4.6.

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Induction of helical mesophases by incorporating chiral dopants into the nematics matrix is the promising modern trends in the chemistry of liquid crystals. This process is associated with a unique phenomenon - an amplification of chirality in liquid-crystalline phases, which ensures the detection of enantiomers by their chiral induction, much more sensitive than other methods. The relevance of this approach is due to the need to create perspective electro-optical devices operating with ultra-low control voltages based on twist effects, chromatographic stationary phases with high chiral selectivity, flexible magnets, photo-sensitive nanostructures, and other smart LC materials. The successful solution of these problems is impossible without experimental research and theoretical comprehension of the mechanisms of third level chiral transfer optically active dopant – nematic liquid crystal. In the last decade, a large number of works have appeared on the solution of these problems. This review is devoted to a generalization of the experimental results and a theoretical description of the transfer of molecular chirality to orientationally ordered systems with the participation of both chiral molecular substituents with an asymmetric carbon atom and planar or quasi-planar fragments chirally distorted relative to each other. The stereochemical aspects of induction associated with the structural correspondences of the dopant and nematic liquid crystal, as well as the main classes of optically active additives, are discussed. Application of metal complexes, both Werner and macroheterocyclic, are presented. Special attention is paid to the results of the mechanisms study of chiral transfer due to various intermolecular interactions: hydrogen bonding, axial coordination, and the formation of inclusion compounds. The high efficiency of induction of spiral mesophases has been demonstrated with a combination of different self-assembly mechanisms in liquid crystal - chiral additive systems.

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Koduri, Geetha Bhavani, Hari Babu Bollikolla, Ramachandran Dittakavi, and Srinivasu Navuluri. "Quantification of Pimavanserin in Bulk and Tablet Dosage Form Using A Stability Indicating High Performance Liquid Chromatographic Method." Pharmaceutical Sciences 24, no. 4 (December 30, 2018): 291–97. http://dx.doi.org/10.15171/ps.2018.42.

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Background: Pimavanserin, an antipsychotic agent, is used to treat patients suffering with Parkinson's disease. Till now no stability indicating reverse phase HPLC method was reported for the quantification of pimavanserin in bulk and tablet dosage form. Hence in the present study, a new sensitive, precise and accurate stability indicating reverse phase HPLC method with photodiode array detector has been developed for the quantification of pimavanserin in bulk and tablet dosage form. Methods: Separation and analysis of pimavanserin was achieved on Kromasil C18 (5 µm, 250 mm × 4.6 mm) column using 0.1M NaH2PO4, methanol and acetonitrile in ratio of 55:30:15 (v/v/v) as mobile phase at 25°C. The flow rate was 1.0 ml/min. The effluents were monitored with detector set at 239 nm. The method validation was done with regard to the guidelines by the International Conference on Harmonization. Pimavanserin was subjected to acid, alkali and neutral hydrolysis, hydrogen peroxide oxidation, thermal degradation, and photo (sunlight) degradation. Results: Linear relationship was obtained between the concentration of drug and peak area response in the range of 4.25-34.0 µg/ml. The limits of detection and quantitation were found to be 0.027 µg/ml and 0.089 µg/ml, respectively. All the validation characteristics were within the acceptance criteria. The peaks of degradation products were well resolved from the pimavanserin peak. Conclusion: The developed and validated method is able to quantify the pimavanserin in the presence of degradation products.

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Sachs, Michael, Benjamin Poulter, Zhaoyuan Yang, Niranjan Govind, Robert Schoenlein, Munira Khalil, and Elisa Biasin. "Impact of Solvent-Solute Hydrogen Bonding on Ultrafast Electron Transfer in a Trimetallic Iron-Ruthenium Complex." ECS Meeting Abstracts MA2022-02, no. 48 (October 9, 2022): 1807. http://dx.doi.org/10.1149/ma2022-02481807mtgabs.

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Transition metal complexes (TMCs) are widely used as light absorbers and catalysts for photochemical energy conversion processes such as photocatalytic reactions in liquid environments. Of particular interest are TMCs which incorporate multiple bridged metal centres because they represent a step towards more complex supramolecular assemblies that can ultimately enable control of the charge flow in solution-based photo-redox processes. However, the development of design guidelines for such molecular assemblies is impeded by an incomplete understanding of the coupling between their electronic and nuclear dynamics, including the interplay of TMCs with their liquid environment upon photoexcitation. Probing the involved processes requires high spatial sensitivity towards electronic motion and the ability to capture atomic motion on ultrafast timescales – a combination which is not readily available for optical transient spectroscopic techniques. X-ray free electron lasers (XFELs) have revolutionized the field of ultrafast science in recent years. XFELs generate tuneable and extremely bright X-ray pulses with a typical pulse duration of <30 fs, which are well-suited as an element-specific probe of ultrafast electronic and atomic motion in molecules and materials.1,2 Applied to TMCs, XFEL probes are sensitive to the local electronic structure in such molecular systems as well as to intra- and inter-molecular structural reorganization at an atomic level.3 In this talk, I will present work on the interaction of a linear trimetallic cyanide-bridged iron-ruthenium complex (FeRuFe) with its solvent environment, carried out using the LCLS XFEL facility at SLAC National Accelerator Laboratory. The focus of this study lies on elucidating how photoinduced intramolecular electron transfer processes in FeRuFe are affected by hydrogen bonding interactions between its cyanide ligands and the surrounding solvent molecules. In water, such solvent-solute hydrogen bonding interactions are stronger for Fe(II) than Fe(III), leading to substantial changes in solute-solvent interactions upon photoinduced electron transfer between metal centres. The experiment is performed in a pump-probe geometry on a liquid jet, where a visible/near-infrared pump induces a metal-to-metal charge transfer (MMCT) between Ru and Fe which is followed by an ultrafast back-electron transfer (BET). The excited state dynamics are monitored using hard X-ray pulses as a function of time delay between the laser pump and the X-ray probe pulses. To resolve and correlate electronic and structural dynamics upon MMCT excitation, we simultaneously perform ultrafast Fe Kβ X-ray emission spectroscopy (XES) and X-ray solution scattering (XSS) measurements, where XES is sensitive to the oxidation and spin state of the Fe centres and XSS provides information on atomic motion in solute and solvent, as demonstrated in previous work on a similar system.4 To evaluate the effect of solute-solvent hydrogen bonding interactions on the electron transfer dynamics, we perform measurements in a series of solvents with different hydrogen bonding properties, including water, methanol, and acetonitrile. We find that the BET increases as a function of decreasing hydrogen bonding ability of the solvent, and that distinct signatures of solvation dynamics are present in the scattering data. The resulting molecular level understanding of solvent reorganization coupled to electron transfer demonstrates that the strength and type of solute-solvent interactions are a central factor in determining the outcome of photoinduced charge transfer processes in TMCs. References Bergmann, U. et al. Using X-ray free-electron lasers for spectroscopy of molecular catalysts and metalloenzymes. Nat. Rev. Phys. 3, 264–282 (2021). Schoenlein, R. et al. Recent advances in ultrafast X-ray sources. Philos. Trans. R. Soc. Math. Phys. Eng. Sci. 377, 20180384 (2019). Gaffney, K. J. Capturing photochemical and photophysical transformations in iron complexes with ultrafast X-ray spectroscopy and scattering. Chem. Sci. 12, 8010–8025 (2021). Biasin, E. et al. Direct observation of coherent femtosecond solvent reorganization coupled to intramolecular electron transfer. Nat. Chem. 13, 343–349 (2021).

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Patel, Herit, Jiehao Chen, Yuhang Hu, and Alper Erturk. "Photo-responsive hydrogel-based re-programmable metamaterials." Scientific Reports 12, no. 1 (July 29, 2022). http://dx.doi.org/10.1038/s41598-022-15453-7.

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AbstractThis paper explores a novel programmable metamaterial using stimuli-responsive hydrogels with a demonstration of bandgap formation and tuning. Specifically, a photo-responsive hydrogel beam that can achieve re-programmable periodicity in geometric and material properties through patterned light irradiation is designed. Hydrogels consist of polymeric networks and water molecules. Many unique properties of hydrogels, including bio-compatibility, stimuli-responsiveness, and low dissipation make them ideal for enabling re-programmable metamaterials for manipulating structural dynamic response and wave propagation characteristics. Bandgap generation and tunability in photo-responsive hydrogel-based metamaterial (in the form of a diatomic phononic chain) as well as the effects of system parameters such as light exposure pattern and photo-sensitive group concentration on the bandgap width and center frequency are systematically studied. In agreement with finite-element model simulations, it is observed that an increase in light exposure region size reduces both the bandgap width and center frequency, while an increase in the concentration of photo-sensitive group increases bandgap width, attenuation and reduces its center frequency. This work unveils the potential of stimuli-response hydrogels as a new class of low-loss soft metamaterials, unlike most other soft materials that are too lossy to sustain and exploit wave phenomena.

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Ortiz, Ophir, Ajay Vidyasagar, and Ryan Toomey. "Active Surface Topographies in Constrained Hydrogel Films." MRS Proceedings 1234 (2009). http://dx.doi.org/10.1557/proc-1234-qq05-05.

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AbstractPeriodic wrinkles or corrugations can appear on the free surfaces of constrained hydrogel films. The constraint generates a residual compressive stress that is partially relieved through deviation of free surfaces from a planar configuration. The morphology, amplitude and wavelength of the surface instability are generally well-defined and depend on the strength of the constraint. If swelling of the hydrogel overcomes the constraint, the film can slip along its substrate, altering the resultant compressive stress and surface topography. By tuning this slippage, we aim to direct the surface features presented by thin hydrogel films. Active control of surface morphology could have important implications in several applications ranging from sensors to controlled cell attachment and detachment.In this work, we discuss a method of tuning the amount of slippage and surface topography of patterned poly(N-isopropylacrylamide) (poly-NIPAAm) films. The films were fabricated from photo-crosslinkable polymers comprising NIPAAm and photo-active methacroyloxy-benzophenone (MaBP) monomers. The patterned films were anchored to a substrate through a hydrogen-bonding self-assembled monolayer. The relationship between pattern geometry, pattern dimensions, and solvent were investigated with respect to the mechanical instability generated at the free surface. We observed that the wavelength, width, and amplitude of the instability always increased with the thickness of the polymer pattern. The morphology of the surface instability, however, was especially sensitive to thickness of the pattern, the solvent, and the spatial position with respect to the edge of polymer pattern. If the slippage of the film against the substrate is minimal, a wrinkle pattern in the form of bicusps was observed. If the compressive stress exceeded the hydrogen-bonding anchors, slippage of the film generated either a blister pattern or a honeycomb pattern.

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Xing, Jianyu, Bin Yang, Wenwen Dang, Jingchang Li, and Bo Bai. "Preparation of Photo/Electro-Sensitive Hydrogel and Its Adsorption/Desorption Behavior to Acid Fuchsine." Water, Air, & Soil Pollution 231, no. 5 (May 2020). http://dx.doi.org/10.1007/s11270-020-04582-2.

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Narayanan, Anakha, Fahidha K. S, Godwin Babu, Nandana V, Raji M K, Anu Abraham, and Neeba Babu. "Formulation and Evaluation of Skin Invigorating Caffeine Face Mask." International Journal of Pharmaceutical Sciences Review and Research, August 15, 2022, 86–89. http://dx.doi.org/10.47583/ijpsrr.2022.v75i02.014.

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Skin health is important in providing an aesthetic appeal and also in personal health. Facial cosmetics keep skin hydrated and remove sebum and impurities from skin thus maintaining proper skin health. It imparts a psychosocial effect on people. Cosmetics intended especially for facial application protects the facial skin, which can be cream, lotion, face mask etc. The use of suitable face masks according to the facial skin types result in healthy skin. Hydrogel masks provide cooling and soothing effects to sensitive skin. Hydrogels have high-water content and their hydrophilic base creates a matrix to the skin, thus allows high efficacy in delivering active ingredients into the skin, thus suitable as facial mask ingredient. Caffeine hydrogel face mask containing caffeine and sodium alginate can be useful for multi-purpose. In this study 1.5% caffeine was formulated with a concentration of 4% sodium alginate to form the hydrogel face mask. Caffeine is being increasingly used in cosmetics due to its anti-aging, anti-oxidant and wound healing properties. It helps protect cell against UV radiation and slows down the process of photo aging. The physical stability of hydrogel face mask was evaluated by organoleptic observation, viscosity, pH, spreadability, hydrogel mask acidity and drying time measurements. The results showed that the hydrogel face mask remained stable in colour and odor for 12 weeks. The study revealed that the hydrogel face mask containing caffeine is stable and has good physical characteristics which makes the hydrogel face mask satisfactory for use as a neutracosmeceutical product. The hydrogel mask tested in this study is very effective in improving skin hydration and skin radiance, encouraging an even skin tone, reducing skin pigmentation and promote young looking skin, reducing the signs of aging.

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Rifaie-Graham, Omar, Jonathan Yeow, Adrian Najer, Richard Wang, Rujie Sun, Kun Zhou, Tristan N. Dell, et al. "Photoswitchable gating of non-equilibrium enzymatic feedback in chemically communicating polymersome nanoreactors." Nature Chemistry, November 7, 2022. http://dx.doi.org/10.1038/s41557-022-01062-4.

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AbstractThe circadian rhythm generates out-of-equilibrium metabolite oscillations that are controlled by feedback loops under light/dark cycles. Here we describe a non-equilibrium nanosystem comprising a binary population of enzyme-containing polymersomes capable of light-gated chemical communication, controllable feedback and coupling to macroscopic oscillations. The populations consist of esterase-containing polymersomes functionalized with photo-responsive donor–acceptor Stenhouse adducts (DASA) and light-insensitive semipermeable urease-loaded polymersomes. The DASA–polymersome membrane becomes permeable under green light, switching on esterase activity and decreasing the pH, which in turn initiates the production of alkali in the urease-containing population. A pH-sensitive pigment that absorbs green light when protonated provides a negative feedback loop for deactivating the DASA–polymersomes. Simultaneously, increased alkali production deprotonates the pigment, reactivating esterase activity by opening the membrane gate. We utilize light-mediated fluctuations of pH to perform non-equilibrium communication between the nanoreactors and use the feedback loops to induce work as chemomechanical swelling/deswelling oscillations in a crosslinked hydrogel. We envision possible applications in artificial organelles, protocells and soft robotics.

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Yan, Huixian, Hengdi Su, and Zheng Zhong. "Modeling of the Photo-Thermal-pH Triple-Responsive Hydrogels Considering the Coupled Effect of Photothermal Conversion and Electrochemistry." Journal of Applied Mechanics 87, no. 7 (May 5, 2020). http://dx.doi.org/10.1115/1.4046919.

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Abstract Photo-thermal-pH triple-responsive hydrogels are special kinds of smart materials which can respond to changes in ambient temperature, pH, and light intensity simultaneously. In this paper, a field theory is developed for the photo-thermal-pH triple-responsive hydrogels by incorporating effects of dissociation of acidic groups and photo-thermal conversion into the thermodynamic theory of temperature-sensitive hydrogels. Constitutive equations are derived by means of the free energy imbalance inequality. The feasibility of the presented model is tested and validated by comparing the simulation results for stress-free swelling with the available experimental data. Moreover, the sensitivities of the presented model to changes in temperature, pH, and light intensity are further studied through the biaxial constrained swelling case, and the factors affecting deformation is investigated numerically.

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Senol, Sebnem, and Emel Akyol. "Preparation and characterization of pH-sensitive hydrogels from photo-crosslinked poly(ethylene glycol) diacrylate incorporating titanium dioxide." Materials Science-Poland, November 18, 2020. http://dx.doi.org/10.2478/msp-2020-0054.

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AbstractThe purpose of the present investigation was to prepare pH-sensitive hydrogels from photo-crosslinked poly(ethylene glycol) diacrylate (PEG-DA). Rutile titanium dioxide (TiO2) was employed to modify the PEG-DA hydrogels. The rutile titanium dioxide (TiO2) nanoparticles were prepared by direct oxidation of titanium in the presence of polyethylene glycol (PEG) at high temperature. The nanoparticles were characterized by FT-IR, XRD and SEM. The influence of experimental conditions, such as pH, type and amount of photoinitiators on the release profiles of donepezil hydrochloride (active pharmaceutical ingredient for Alzheimer disease) from modified PEG-DA hydrogels, was investigated. The drug release processes were analyzed kinetically using zero-order, first-order, Hixson-Crowell and Peppas models.

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Baugh, J., D. X. Han, A. Kleinhammes, Q. Wang, and Y. Wu. "Diamagnetic Susceptibility of Micron Thick a-Si:H Films Measured via Proton NMR: A Probe of Structural Disorder." MRS Proceedings 609 (2000). http://dx.doi.org/10.1557/proc-609-a16.3.

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ABSTRACTMagnetic susceptibility is predicted to be sensitive to structural disorder in the group IV elemental semiconductors. A proton nuclear magnetic resonance (NMR) technique is shown to precisely measure bulk magnetic susceptibilities (χ) of hot-wire (HW) CVD a-Si:H films as- deposited on quartz substrates. Differences in χ correlate with growth rate, but not with hydrogen content or deposition temperature. Qualitative agreement is found between smaller diamagnetic susceptibility (less average disorder) and desirable electronic properties measured by photo- and dark conductivity on the same samples. Comparing films with similar hydrogen distribution and content (as evidenced by the NMR spectra) allows the unambiguous identification of the importance of overall Si network structural disorder in the metastability of a-Si:H.

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Journal articles on the topic 'Photo-sensitive Hydrogel'

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