Journal articles: 'PH-responsive linker'

1

Xiao, Zeyun, Ross Andrew Lennox Wylie, Emma Ruth Lucille Brisson, and Luke Andrew Connal. "pH-responsive fluorescent hydrogels using a new thioflavin T cross-linker." Journal of Polymer Science Part A: Polymer Chemistry 54, no. 5 (November 12, 2015): 591–95. http://dx.doi.org/10.1002/pola.27974.

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Zhang, Junliang, Joji Tanaka, Pratik Gurnani, Paul Wilson, Matthias Hartlieb, and Sébastien Perrier. "Self-assembly and disassembly of stimuli responsive tadpole-like single chain nanoparticles using a switchable hydrophilic/hydrophobic boronic acid cross-linker." Polymer Chemistry 8, no. 28 (2017): 4079–87. http://dx.doi.org/10.1039/c7py00828g.

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Li, Bingqiang, Meng Shan, Xiang Di, Chu Gong, Lihua Zhang, Yanming Wang, and Guolin Wu. "A dual pH- and reduction-responsive anticancer drug delivery system based on PEG–SS–poly(amino acid) block copolymer." RSC Advances 7, no. 48 (2017): 30242–49. http://dx.doi.org/10.1039/c7ra04254j.

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Dey, Soma, and K. Sreenivasan. "Conjugating curcumin to water soluble polymer stabilized gold nanoparticles via pH responsive succinate linker." Journal of Materials Chemistry B 3, no. 5 (2015): 824–33. http://dx.doi.org/10.1039/c4tb01731e.

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Rao N, Vijayakameswara, ShivshankarR Mane, Abhinoy Kishore, Jayasri Das Sarma, and Raja Shunmugam. "Norbornene Derived Doxorubicin Copolymers as Drug Carriers with pH Responsive Hydrazone Linker." Biomacromolecules 13, no. 1 (December 6, 2011): 221–30. http://dx.doi.org/10.1021/bm201478k.

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Thirupathi, Kokila, Thi Tuong Vy Phan, Madhappan Santhamoorthy, Vanaraj Ramkumar, and Seong-Cheol Kim. "pH and Thermoresponsive PNIPAm-co-Polyacrylamide Hydrogel for Dual Stimuli-Responsive Controlled Drug Delivery." Polymers 15, no. 1 (December 29, 2022): 167. http://dx.doi.org/10.3390/polym15010167.

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The therapeutic delivery system with dual stimuli-responsiveness has attracted attention for drug delivery to target sites. In this study, we used free radical polymerization to develop a temperature and pH-responsive poly(N-isopropyl acrylamide)-co-poly(acrylamide) (PNIPAM-co-PAAm). PNIPAm-co-PAAm copolymer by reacting with N-isopropyl acrylamide (NIPAm) and acrylamide (Am) monomers. In addition, the synthesized melamine-glutaraldehyde (Mela-Glu) precursor was used as a cross-linker in the production of the melamine cross-linked PNIPAm-co-PAAm copolymer hydrogel (PNIPAm-co-PAAm-Mela HG) system. The temperature-responsive phase transition characteristics of the resulting PNIPAM-co-PAAm-Mela HG systems were determined. Furthermore, the pH-responsive drug release efficiency of curcumin was investigated under various pH and temperature circumstances. Under the combined pH and temperature stimuli (pH 5.0/45 °C), the PNIPAm-co-PAAm-Mela HG demonstrated substantial drug loading (74%), and nearly complete release of the loaded drug was accomplished in 8 h. Furthermore, the cytocompatibility of the PNIPAm-co-PAAm-Mela HG was evaluated on a human liver cancer cell line (HepG2), and the findings demonstrated that the prepared PNIPAm-co-PAAm-Mela HG is biocompatible. As a result, the PNIPAm-co-PAAm-Mela HG system might be used for both pH and temperature-stimuli-responsive drug delivery.

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Mehra, Saloni, Safiya Nisar, Sonal Chauhan, Gurmeet Singh, Virender Singh, and Sunita Rattan. "A dual stimuli responsive natural polymer based superabsorbent hydrogel engineered through a novel cross-linker." Polymer Chemistry 12, no. 16 (2021): 2404–20. http://dx.doi.org/10.1039/d0py01729a.

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Ali, Shaikh A., Shuaib A. Mubarak, Ibrahim Y. Yaagoob, Zeeshan Arshad, and Mohammad A. J. Mazumder. "A sorbent containing pH-responsive chelating residues of aspartic and maleic acids for mitigation of toxic metal ions, cationic, and anionic dyes." RSC Advances 12, no. 10 (2022): 5938–52. http://dx.doi.org/10.1039/d1ra09234k.

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Cycloterpolymerization of diallylaminoaspartic acid hydrochloride (I), maleic acid (II) and a cross-linker (III) afforded a new pH-responsive resin (IV), loaded with four CO2H and a chelating motif of NH+⋯CO2− in each repeating unit.

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Ruckenstein, Eli, and Hongmin Zhang. "A Novel Breakable Cross-Linker and pH-Responsive Star-Shaped and Gel Polymers." Macromolecules 32, no. 12 (June 1999): 3979–83. http://dx.doi.org/10.1021/ma990016d.

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Aho, Aapo, Mika Sulkanen, Heidi Korhonen, and Pasi Virta. "Conjugation of Oligonucleotides to Peptide Aldehydes via a pH-Responsive N-Methoxyoxazolidine Linker." Organic Letters 22, no. 17 (August 17, 2020): 6714–18. http://dx.doi.org/10.1021/acs.orglett.0c01815.

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Jin, Can, Wenjia Song, Tuan Liu, Junna Xin, William C. Hiscox, Jinwen Zhang, Guifeng Liu, and Zhenwu Kong. "Temperature and pH Responsive Hydrogels Using Methacrylated Lignosulfonate Cross-Linker: Synthesis, Characterization, and Properties." ACS Sustainable Chemistry & Engineering 6, no. 2 (January 10, 2018): 1763–71. http://dx.doi.org/10.1021/acssuschemeng.7b03158.

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Wang, Chenxu, Yan Du, Qiong Wu, Shuguang Xuan, Jiajing Zhou, Jibin Song, Fangwei Shao, and Hongwei Duan. "Stimuli-responsive plasmonic core–satellite assemblies: i-motif DNA linker enabled intracellular pH sensing." Chemical Communications 49, no. 51 (2013): 5739. http://dx.doi.org/10.1039/c3cc80005a.

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Li, Shangyang, Aiyou Hao, Jian Shen, Ningzhao Shang, and Chun Wang. "UV and pH-responsive supra-amphiphiles driven by combined interactions for controlled self-assembly behaviors." Soft Matter 14, no. 11 (2018): 2112–17. http://dx.doi.org/10.1039/c8sm00118a.

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In order to fabricate a novel supra-amphiphile with multiple stimulus properties, we developed the strategy of introducing a bi-functional linker to bridge the hydrophilic and hydrophobic building blocks together, by utilizing more than one kind of interaction.

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Yadav, Eqvinshi, Anil Kumar Khatana, Sharol Sebastian, and Manoj K. Gupta. "DAP derived fatty acid amide organogelators as novel carrier for drug incorporation and pH-responsive release." New Journal of Chemistry 45, no. 1 (2021): 415–22. http://dx.doi.org/10.1039/d0nj04611f.

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Low-molecular mass fatty acid amide gelators were synthesized using 2,6-diaminopyridine as a linker and alkyl chains of varying lengths. The prepared organogel-elusions are able to trap and release ibuprofen molecule without changing its structure and activity.

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Liu, Rui, Ying Zhang, Xiang Zhao, Arun Agarwal, Leonard J. Mueller, and Pingyun Feng. "pH-Responsive Nanogated Ensemble Based on Gold-Capped Mesoporous Silica through an Acid-Labile Acetal Linker." Journal of the American Chemical Society 132, no. 5 (February 10, 2010): 1500–1501. http://dx.doi.org/10.1021/ja907838s.

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Xu, Xuewei, Adam E. Smith, and Charles L. McCormick. "Facile 'One-Pot' Preparation of Reversible, Disulfide-Containing Shell Cross-Linked Micelles from a RAFT-Synthesized, pH-Responsive Triblock Copolymer in Water at Room Temperature." Australian Journal of Chemistry 62, no. 11 (2009): 1520. http://dx.doi.org/10.1071/ch09255.

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A pH-responsive triblock copolymer, α-methoxy poly(ethylene oxide)-b-poly(N-(3-aminopropyl) methacrylamide)-β-poly(2-(diisopropylamino)ethyl methacrylate) (mPEO-PAPMA-PDPAEMA), was synthesized via aqueous RAFT polymerization. This triblock copolymer dissolves in aqueous solution at low pH (<5.0) due to protonation of primary amine residues on the PAPMA block and tertiary amine residues on the PDPAEMA block. Above pH 6.0, the copolymer unimers self-assemble into micelles consisting of PDPAEMA cores, PAPMA shells, and mPEO coronas. Dynamic light scattering studies indicated a hydrodynamic diameter of 92 nm at pH 9.0. A bifunctional, reversible cross-linker, dimethyl 3,3′-dithiobispropionimidate (DTBP), was used to cross-link the micelles. The ‘one-pot’ formation of shell cross-linked (SCL) micelles was accomplished at room temperature in water by mixing the triblock copolymers and DTBP at pH 3.0, and slowly increasing the solution pH to 9.0 leading to the simultaneous formation of micelles and cross-linking. These SCL micelles are readily cleaved by the addition of the reducing agent, dithiothreitol, and can be re-cross-linked simply by exposure to air. Such SCL micelles have potential as nanocarriers for controlled release of therapeutic and diagnostic agents because the in situ cleavage of the disulfide linkages would not only allow release of bioactive agents, but also permit renal clearance of the resulting unimeric components.

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Romeo, Alice, Mattia Falconi, Alessandro Desideri, and Federico Iacovelli. "Reconstructing the Free Energy Profiles Describing the Switching Mechanism of a pH-Dependent DNA Nanodevice from ABMD Simulations." Applied Sciences 11, no. 9 (April 29, 2021): 4052. http://dx.doi.org/10.3390/app11094052.

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The pH-responsive behavior of six triple-helix DNA nanoswitches, differing in the number of protonation centers (two or four) and in the length of the linker (5, 15 or 25 bases), connecting the double-helical region to the single-strand triplex-forming region, was characterized at the atomistic level through Adaptively Biased Molecular Dynamics simulations. The reconstruction of the free energy profiles of triplex-forming oligonucleotide unbinding from the double helix identified a different minimum energy path for the three diprotic nanoswitches, depending on the length of the connecting linker and leading to a different per-base unbinding profile. The same analyses carried out on the tetraprotic switches indicated that, in the presence of four protonation centers, the unbinding process occurs independently of the linker length. The simulation data provide an atomistic explanation for previously published experimental results showing, only in the diprotic switch, a two unit increase in the pKa switching mechanism decreasing the linker length from 25 to 5 bases, endorsing the validity of computational methods for the design and refinement of functional DNA nanodevices.

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Dragojevic, Sonja, Lindsay Turner, and Drazen Raucher. "Circumventing Doxorubicin Resistance Using Elastin-like Polypeptide Biopolymer-Mediated Drug Delivery." International Journal of Molecular Sciences 23, no. 4 (February 19, 2022): 2301. http://dx.doi.org/10.3390/ijms23042301.

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Although doxorubicin (dox), an anthracycline antibiotic, is widely used and effective in treating cancer, its treatment efficiency is limited by low blood plasma solubility, poor pharmacokinetics, and adverse side effects, including irreversible cardiotoxicity. Moreover, cancer cells often develop drug resistance over time, which decreases the efficacy of anti-cancer drugs, including dox. In this study, we examine a macromolecular drug delivery system for its ability to specifically deliver doxorubicin to cancer cells with and without drug resistance. This drug delivery system consists of a multi-part macromolecule, which includes the following: elastin-like polypeptide (ELP), cell penetrating peptide (CPP), a cleavable linker (releasing at low pH), and a derivative of doxorubicin. ELP is thermally responsive and improves drug solubility, while the CPP mediates cellular uptake of macromolecules. We compared cytotoxicity of two doxorubicin derivatives, where one is cleavable (DOXO) and contains a pH-sensitive linker and releases dox in an acidic environment, and the other is non-cleavable (ncDox) doxorubicin. Cytotoxicity, apoptosis, cell cycle distribution and mechanism of action of these constructs were tested and compared between dox-responsive MCF-7 and dox-resistant NCI/ADR cell lines. Dox delivered by the ELP construct is comparably toxic to both sensitive and drug resistant cell lines, compared to unconjugated doxorubicin, and given the pharmacokinetic and targeting benefits conveyed by conjugation to ELP, these biopolymers have potential to overcome dox resistance in vivo.

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Jeong, Jae Hyun, John J. Schmidt, Chaenyung Cha, and Hyunjoon Kong. "Tuning responsiveness and structural integrity of a pH responsive hydrogel using a poly(ethylene glycol) cross-linker." Soft Matter 6, no. 16 (2010): 3930. http://dx.doi.org/10.1039/c0sm00094a.

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Aho, Aapo, Antti Äärelä, Heidi Korhonen, and Pasi Virta. "Expanding the Scope of the Cleavable N-(Methoxy)oxazolidine Linker for the Synthesis of Oligonucleotide Conjugates." Molecules 26, no. 2 (January 18, 2021): 490. http://dx.doi.org/10.3390/molecules26020490.

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Oligonucleotides modified by a 2′-deoxy-2′-(N-methoxyamino) ribonucleotide react readily with aldehydes in slightly acidic conditions to yield the corresponding N-(methoxy)oxazolidine-linked oligonucleotide-conjugates. The reaction is reversible and dynamic in slightly acidic conditions, while the products are virtually stable above pH 7, where the reaction is in a ‘‘switched off-state’’. Small molecular examinations have demonstrated that aldehyde constituents affect the cleavage rate of the N-(methoxy)oxazolidine-linkage. This can be utilized to adjust the stability of this pH-responsive cleavable linker for drug delivery applications. In the present study, Fmoc-β-Ala-H was immobilized to a serine-modified ChemMatrix resin and used for the automated assembly of two peptidealdehydes and one aldehyde-modified peptide nucleic acid (PNA). In addition, a triantennary N-acetyl-d-galactosamine-cluster with a β-Ala-H unit has been synthesized. These aldehydes were conjugated via N-(methoxy)oxazolidine-linkage to therapeutically relevant oligonucleotide phosphorothioates and one DNA-aptamer in 19–47% isolated yields. The cleavage rates of the conjugates were studied in slightly acidic conditions. In addition to the diverse set of conjugates synthesized, these experiments and a comparison to published data demonstrate that the simple conversion of Gly-H to β-Ala-H residue resulted in a faster cleavage of the N-(methoxy)oxazolidine-linker at pH 5, being comparable (T0.5 ca 7 h) to hydrazone-based structures.

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Knežević, Nikola Ž., Nebojša Ilić, and Goran N. Kaluđerović. "Mesoporous Silica Nanoparticles for pH-Responsive Delivery of Iridium Metallotherapeutics and Treatment of Glioblastoma Multiforme." Inorganics 10, no. 12 (December 8, 2022): 250. http://dx.doi.org/10.3390/inorganics10120250.

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Using nanoparticles for controlled drug delivery to cancer, in response to its weakly acidic environment, represents a promising approach toward increasing the effectiveness and reducing the adverse effects of cancer therapy. Hence, the aim of this study is to construct novel mesoporous silica nanoparticle (MSN)-based acidification-responsive drug delivery systems for targeted cancer therapy. Herein, the surface of MSN is covalently functionalized with Ir(III)-based complex through a pH-cleavable hydrazone-based linker and characterized by nitrogen sorption, SEM, FTIR, EDS, TGA, DSC, DLS, and zeta potential measurements. Enhanced release of Ir(III)-complexes is evidenced by UV/VIS spectroscopy at the weakly acidic environments (pH 5 and pH 6) in comparison to the release at physiological conditions. The in vitro toxicity of the prepared materials is tested on healthy MRC-5 cells while their potential for the efficient treatment of glioblastoma multiforme is demonstrated on the U251 cell line.

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Taira, Shogo, Yuriko Usukura, Mitsukuni Nishida, Kengo Shigetomi, and Yasumitsu Uraki. "Characterization of a lignin-based gel responsive to aqueous binary solvents and pH." Holzforschung 75, no. 8 (January 6, 2021): 765–72. http://dx.doi.org/10.1515/hf-2020-0220.

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Abstract A lignin-based gel (AL-PE gel) was obtained from hardwood acetic acid lignin (AL) and poly(ethylene glycol) diglycidyl ether (PE) as a cross-linker at a high AL concentration, while the reaction at a lower AL concentration yielded an amphipathic derivative (am-AL-PE). The gel has been reported to swell in aqueous ethanol but shrink in pure water and ethanol. In the present work, swelling behaviors in other aqueous binary solvents and the swelling mechanism were investigated to explore novel lignin-based functional materials, such as stimuli-and/or environment-responsive gels. The AL-PE gel swelled in aqueous methanol, isopropanol, acetone, and tetrahydrofuran, and the order of swelling in the solvents was consistent with that of the am-AL-PE. Spin-spin relaxation time (T 2 ) measurements with 1H NMR analysis of the gel in aqueous acetone revealed that gel swelling was closely related to an increasing T 2 of acetone bound to the gel network. The nature of the lignin moiety in the gel also enabled a pH response, and the amphipathic nature of the gel provided it with a function as an absorbent for cationic surfactants. The results of this study can contribute to the valorization of lignin as a main component for solvent sensors and environmental purification materials.

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Mu, Mengya, Yingzhan Li, Hou-Yong Yu, Ziheng Li, Yiwen Cao, and Xinyi Chen. "Construction of Nanocellulose Aerogels with Mechanical Flexibility and pH-Responsive Properties via a Cross-Linker Structure Design Strategy." ACS Sustainable Chemistry & Engineering 9, no. 29 (July 14, 2021): 9951–60. http://dx.doi.org/10.1021/acssuschemeng.1c03503.

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Zhu, Shu Yu, Zhong Li Niu, Xiao Ting Zhang, Dan Yue Wang, Jia Ming Xu, Bin Sun, Mei Fang Zhu, and Xiao Ze Jiang. "Doxorubicin Loading Capacity of Shell Cross-Linked Micelles with pH-Responsive Core as Anticancer Drug Delivery Nanocarriers." Materials Science Forum 898 (June 2017): 2366–72. http://dx.doi.org/10.4028/www.scientific.net/msf.898.2366.

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Detailed studies were performed to probe the effects of the cross-linking layer microstructure of pH-responsive shell cross-linked (SCL) micelles on the loading capacity of doxorubicin (DOX). Well-defined poly [(ethylene glycol)-block-2-(dimethylamino) ethyl methacrylate-block-2-(diethylamino) methacrylate] (PEG-b-P(DMA- co-QDMA)-b-PDEA) copolymer with “clickable” moieties in the middle block by the quaternization with propargyl bromide dissolved molecularly in acidic solution; micellization occurred at alkaline solution to form three-layer “onionlike” micelles constituting PDEA cores, P(DMA-co-QDMA) inner shells, and PEG coronas. Two types of cross-linker bearing azide group: 1,6-bisazidehexane and bis-(azidoethyl) disulfide were utilized to prepare the SCL micelles with different cross-linking layer microstructure via click chemistry at basic aqueous media. The results showed that two types of SCL micelles possessed excellent stability. In neutral solution, these SCL micelles still maintained structural integrity, and the average hydrodynamic diameter of SCL micelles 1 and SCL micelles 2 increased to 80 nm and 90 nm, respectively. In the acidic solution, due to the complete protonated of the PDEA core, the sizes of the two types of SCL micelles increased to 95 nm and 110 nm, respectively, which were favorable for the diffusion of the encapsulated drug in the core. Moreover, the cross-linking degree had no effect on the size of SCL micelles. The loading efficiency and loading content of the SCL micelles were significantly better than those of the uncross-linked micelles, and loading capacity did not vary with degree of cross-linking. However, the SCL micelles 1 demonstrated better loading capacity. This study could be a guidance for the future research on the effects of the cross-linking layer microstructure on controlled doxorubicin release.

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Kushio, Satoshi, Akira Tsuchiya, Yuta Nakamura, Takanobu Nobori, Chan Woo Kim, Guo Xi Zhao, Taiki Funamoto, et al. "CANCER-SPECIFIC GENE CARRIERS RESPONDING TO CANCER MICROENVIRONMENT: ACIDOSIS AND HYPER-ACTIVATED PROTEIN KINASES." Biomedical Engineering: Applications, Basis and Communications 25, no. 05 (October 2013): 1340005. http://dx.doi.org/10.4015/s101623721340005x.

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Protein kinase (PK)-responsive gene carriers modified with polyethylene glycol (PEG) chains using an acid-labile linker were developed. These carriers were obtained by modifying the PEG chains and substrate peptides for the PKs (PKA or PKCα) on the branched polyethyleneimine main chain. Polyplexes formed from these carriers and plasmid DNA (pDNA) were stably dispersed under neutral pH medium. The polyplexes were also taken up by cells on the release of the PEG chains under the slightly acidic extracellular pH associated with cancer cells. The polyplexes taken up by cells resulted in gene expression when the substrate peptides were phosphorylated by the intracellular PKs to release pDNA from the polyplexes. These novel gene carriers are expected to be promising for cancer-specific gene therapy via intravenous administration.

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Chen, Mian, Xiaoxiao He, Kemin Wang, Dinggeng He, Shuna Yang, Pengchao Qiu, and Suye Chen. "A pH-responsive polymer/mesoporous silica nano-container linked through an acid cleavable linker for intracellular controlled release and tumor therapy in vivo." J. Mater. Chem. B 2, no. 4 (2014): 428–36. http://dx.doi.org/10.1039/c3tb21268h.

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Ma, Gejun, Deshan Li, Ji Wang, Xuefei Zhang, and Haoyu Tang. "Methoxy-Poly(ethylene glycol)-block-Poly(ε-caprolactone) Bearing Pendant Aldehyde Groups as pH-Responsive Drug Delivery Carrier." Australian Journal of Chemistry 66, no. 12 (2013): 1576. http://dx.doi.org/10.1071/ch13297.

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A biodegradable amphiphilic block copolymer of methoxy poly(ethylene glycol)-block-poly(ϵ-caprolactone) bearing pendant aldehyde groups was synthesised by a combination of ring-opening polymerisation and thio-bromo ‘click’ chemistry. The free aldehyde groups on the copolymer were reacted with hydrophobic payloads (p-methoxylaniline as a model drug) by a benzoic–imine linker, which was responsive to pH change. NMR, FTIR, and gel permeation chromatography analysis confirmed the copolymer structures. In vitro release studies revealed that under acid stimulus, hydrolysis of the benzoic–imine bond resulted in a rapid drug release. This new amphiphilic block copolymer is expected to have promising applications in biodegradable controlled drug delivery systems.

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Zhang, Wei-Jin, Shuwei Li, Veena Vijayan, Jun Seok Lee, Sung Soo Park, Xiuguo Cui, Ildoo Chung, et al. "ROS- and pH-Responsive Polydopamine Functionalized Ti3C2Tx MXene-Based Nanoparticles as Drug Delivery Nanocarriers with High Antibacterial Activity." Nanomaterials 12, no. 24 (December 9, 2022): 4392. http://dx.doi.org/10.3390/nano12244392.

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Premature drug release and poor controllability is a challenge in the practical application of tumor therapy, which may lead to poor chemotherapy efficacy and severe adverse effects. In this study, a reactive oxygen species (ROS)-cleavable nanoparticle system (MXene-TK-DOX@PDA) was designed for effective chemotherapy drug delivery and antibacterial applications. Doxorubicin (DOX) was conjugated to the surface of (3-aminopropyl)triethoxysilane (APTES)-functionalized MXene via an ROS-cleavable diacetoxyl thioketal (TK) linkage. Subsequently, the surfaces of the MXene nanosheets were coated with pH-responsive polydopamine (PDA) as a gatekeeper. PDA endowed the MXene-TK-DOX@PDA nanoparticles with superior biocompatibility and stability. The MXene-TK-DOX@PDA nanoparticles had an ultrathin planar structure and a small lateral size of approximately 180 nm. The as-synthesized nanoparticles demonstrated outstanding photothermal conversion efficiency, superior photothermal stability, and a remarkable extinction coefficient (23.3 L g−1 cm−1 at 808 nm). DOX exhibited both efficient ROS-responsive and pH-responsive release performance from MXene-TK-DOX@PDA nanoparticles due to the cleavage of the thioketal linker. In addition, MXene-TK-DOX@PDA nanoparticles displayed high antibacterial activity against both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) within 5 h. Taken together, we hope that MXene-TK-DOX@PDA nanoparticles will enrich the drug delivery system and significantly expand their applications in the biomedical field

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Batool, Nighat, Rai Muhammad Sarfraz, Asif Mahmood, Umaira Rehman, Muhammad Zaman, Shehla Akbar, Diena M. Almasri, and Heba A. Gad. "Development and Evaluation of Cellulose Derivative and Pectin Based Swellable pH Responsive Hydrogel Network for Controlled Delivery of Cytarabine." Gels 9, no. 1 (January 12, 2023): 60. http://dx.doi.org/10.3390/gels9010060.

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In the present study, pH-sensitive, biodegradable, and biocompatible Na-CMC/pectin poly(methacrylic acid) hydrogels were synthesized using an aqueous free radical polymerization technique and encapsulated by cytarabine (anti-cancer drug). The aim of the project was to sustain the plasma profile of cytarabine through oral administration. Sodium carboxymethyl cellulose (Na-CMC) and pectin were cross-linked chemically with methacrylic acid (MAA) as a monomer, using methylene bisacrylamide (MBA) as cross-linker and ammonium per sulfate (APS) as an initiator. Prepared hydrogel formulations were characterized for their texture, morphology, cytarabine loading efficiency, compositional and structural properties, thermal nature, stability, swelling response, drug release profile (pH 1.2 and pH 7.4), and in-vivo pharmacokinetic evaluation. Cytarabine-loaded hydrogels were also evaluated for their safety profile by carrying out toxicity studies in rabbits. Results demonstrated efficient encapsulation of cytarabine into the prepared network with loading ranging from 48.5–82.3%. The highest swelling ratio of 39.38 and maximum drug release of 83.29–85.27% were observed at pH 7.4, highlighting the pH responsiveness of the grafted system. Furthermore, cytarabine maximum release was noticed over 24 h, ensuring a sustained release response for all formulations. Histopathological studies and hemolytic profiles confirmed that the prepared hydrogel system was safe, biocompatible, and non-irritant, showing no symptoms of any toxicities and degeneration in organs. Moreover, pharmacokinetic estimation of the cytarabine-loaded hydrogel showed a remarkable increase in the plasma half-life from 4.44 h to 9.24 h and AUC from 22.06 μg/mL.h to 56.94 μg/mL.h. This study revealed that the prepared hydrogel carrier system has excellent abilities in delivering the therapeutic moieties in a controlled manner.

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Cerrato, Giuseppina, Gianmario Martra, Guido Viscardi, and Michela Signoretto. "TiO2-Chitosan Hybrid Materials for Drug Delivery Applications: Conjugation Reaction with a Model Drug and Evaluation of the Functional Properties." Journal of Nanoscience and Nanotechnology 21, no. 5 (May 1, 2021): 2892–900. http://dx.doi.org/10.1166/jnn.2021.19050.

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The combination of TiO2 and chitosan is known to allow the achievement of implantable devices which combines the mechanical properties of TiO2, with the presence of chitosan, which ensures antibacterial properties combined with an in-situ drug-delivery of biomolecules physisorbed and/or covalently linked to chitosan. In this study, 5-aminofluorescein (5-AF), a derivative of fluorescein containing a primary amino group, has been used as model molecule to simulate a drug. This dye is characterized by low cost and low toxicity, and due to its high molar absorptivity it can easily be detected by means of absorption and emission spectroscopies. The combination of 5-AF and maleic anhydride (MA) with TiO2-chitosan materials has generated a range of novel hybrid materials tailored to applications in localized stimuli-responsive drug delivery systems. Maleic anhydride has been used as pH sensitive spacer for the covalent functionalization of the TiO2-chitosan hybrid with MA as linker molecule. This functionalization allowed to obtain a pH-sensitive hybrid material. The efficiency of the functionalization has been verified by means of different physico-chemical characterization techniques. The behaviour of the functionalized materials is related to different parameters, among which the ratio between physisorbed/coordinated and chemisorbed 5-AF and the matrix degradation. Moreover, delivery tests in simulated body solutions at different pH have been performed showing a pH-sensitive drug delivery behaviour and indicating that the release of 5-AF is favoured at basic pH.

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Buchner, Sophie, Andreas Schlundt, Jürgen Lassak, Michael Sattler, and Kirsten Jung. "Structural and Functional Analysis of the Signal-Transducing Linker in the pH-Responsive One-Component System CadC of Escherichia coli." Journal of Molecular Biology 427, no. 15 (July 2015): 2548–61. http://dx.doi.org/10.1016/j.jmb.2015.05.001.

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Azakami, Yuka, Michael Kappl, Syuji Fujii, Shin-ichi Yusa, and Cathy E. McNamee. "Effect of the Addition of a Cross-Linker and the Water pH on the Physical Properties of Films of pH-Responsive Polymer Particles at Air/Water Interfaces." ACS Omega 2, no. 11 (November 13, 2017): 7837–48. http://dx.doi.org/10.1021/acsomega.7b01241.

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Gao, Di, and Pui-Chi Lo. "Combined pH-responsive chemotherapy and glutathione-triggered photosensitization to overcome drug-resistant hepatocellular carcinoma — a SPP/JPP Young Investigator Award paper." Journal of Porphyrins and Phthalocyanines 24, no. 11n12 (October 21, 2020): 1387–401. http://dx.doi.org/10.1142/s1088424620500212.

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Doxorubicin (DOX) resistance, which results in a reduced accumulation of DOX in the nucleus and hence decreased DNA damage, is a major challenge for chemotherapy against hepatocellular carcinoma. In this paper, we combined chemotherapy with photodynamic therapy (PDT) to combat DOX-resistant human hepatocellular carcinoma cells. We have prepared the polymeric micelles conjugating with DOX and zinc(II) phthalocyanine (ZnPc) through a pH-responsive hydrazone linker and a glutathione (GSH)-responsive disulfide linker, respectively. The polymeric micelles (DOX-ZnPc-micelles) exhibited a spherical shape with a size of about 98 nm diameter and showed excellent stability in aqueous solution. Due to the self-quenching of the ZnPc inside the micelles, DOX-ZnPc-micelles did not emit fluorescence upon red light irradiation. Drug release experiments verified that DOX and ZnPc could be released under acidic conditions and reducing environments, respectively. A higher concentration of DOX was internalized into DOX-resistant R-HepG2 cells through the delivery of polymeric micelles when compared with the free DOX, hence DOX-ZnPc-micelles exhibited a significant enhancement in anticancer activity. The IC[Formula: see text] value of DOX against R-HepG2 cells was found to be 21 [Formula: see text]M when combined with PDT and it was 5-fold less than that of a single treatment of DOX (102 [Formula: see text]M). The DOX-ZnPc-micelles could induce cell apoptosis and necrosis on R-HepG2 cells by combined therapeutic modalities, while these micelles induced only apoptosis on HepG2 cells. We have demonstrated that utilization of polymeric micelles can significantly enhance the cellular uptake and cytotoxicity of DOX against R-HepG2 cells when compared with free DOX. Moreover, PDT can act as an adjuvant therapeutic modality and combine with chemotherapy to further improve therapeutic efficacy. Overall speaking, DOX-ZnPc-micelles can overcome DOX resistance and induce a synergistic therapeutic effect against DOX-resistant R-HepG2 cells, hence improving the therapeutic efficacy when compared with monotherapy.

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Suhail, Muhammad, Yi-Han Hsieh, Yu-Fang Shao, Muhammad Usman Minhas, and Pao-Chu Wu. "Formulation and In-Vitro Characterization of pH-Responsive Semi-Interpenetrating Polymer Network Hydrogels for Controlled Release of Ketorolac Tromethamine." Gels 7, no. 4 (October 13, 2021): 167. http://dx.doi.org/10.3390/gels7040167.

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Ketorolac tromethamine is a non-steroidal anti-inflammatory drug used in the management of severe pain. The half-life of Ketorolac tromethamine is within the range of 2.5–4 h. Hence, repeated doses of Ketorolac tromethamine are needed in a day to maintain the therapeutic level. However, taking several doses of Ketorolac tromethamine in a day generates certain complications, such as acute renal failure and gastrointestinal ulceration. Therefore, a polymeric-controlled drug delivery system is needed that could prolong the release of Ketorolac tromethamine. Therefore, in the current study, pH-responsive carbopol 934/sodium polystyrene sulfonate-co-poly(acrylic acid) (CP/SpScPAA) hydrogels were developed by the free radical polymerization technique for the controlled release of Ketorolac tromethamine. Monomer acrylic acid was crosslinked with the polymers carbopol 934 and sodium polystyrene sulfonate by the cross-linker N’,N’-methylene bisacrylamide. Various studies were conducted to evaluate and assess the various parameters of the fabricated hydrogels. The compatibility of the constituents used in the preparation of hydrogels was confirmed by FTIR analysis, whereas the thermal stability of the unreacted polymers and developed hydrogels was analyzed by TGA and DSC, respectively. A smooth and porous surface was indicated by SEM. The crystallinity of carbopol 934, sodium polystyrene sulfonate, and the prepared hydrogels was evaluated by PXRD, which revealed a reduction in the crystallinity of reactants for the developed hydrogels. The pH sensitivity of the polymeric hydrogel networks was confirmed by dynamic swelling and in vitro release studies with two different pH media i.e., pH 1.2 and 7.4, respectively. Maximum swelling was exhibited at pH 7.4 compared to pH 1.2 and, likewise, a greater percent drug release was perceived at pH 7.4. Conclusively, we can demonstrate that the developed pH-sensitive hydrogel network could be employed as a suitable carrier for the controlled delivery of Ketorolac tromethamine.

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Rahman, Mijanur, Paiboon Sreearunothai, and Pakorn Opaprakasit. "Development and Characterization of Photoinduced Acrylamide-Grafted Polylactide Films for Biomedical Applications." International Journal of Polymer Science 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/5651398.

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Surface grafting of biodegradable/biocompatible polylactide (PLA) films by a UV-assisted reaction has been developed by employing a hydrophilic acrylamide (Am) monomer, an N,N′-methylenebisacrylamide (MBAm) cross-linker, and a camphorquinone (CQ)/N,N′-dimethylaminoethylmethacrylate (DMAEMA) photoinitiator/coinitiator system. The accomplishment of the process is confirmed by FTIR and XPS analyses. Physicochemical changes of the grafted PLA films are evaluated in terms of chemical structures, radiation-induced degradation followed by crystallization, morphology, thermal properties, and mechanical behavior. The results reveal that a low degree of PLA degradation through chain scission is observed in both blank and grafted PLA films. This generates more polar chain ends that can further induce crystallization. Results from contact angle measurements indicate that the grafted films have higher hydrophilicity and pH-responsive behavior. The incorporation of PAm on the film’s surface and the induced crystallization lead to improvements in certain aspects of mechanical properties of the films. The materials have high potential for use in biomedical and environmental applications, such as cell culture substrates or scaffolds or pH-sensitive absorbents.

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Aminoleslami, Darya, Sahar Porrang, Parviz Vahedi, and Soodabeh Davaran. "Synthesis and Characterization of a Novel Dual-Responsive Nanogel for Anticancer Drug Delivery." Oxidative Medicine and Cellular Longevity 2022 (September 19, 2022): 1–12. http://dx.doi.org/10.1155/2022/1548410.

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In this study, to reduce the side effects of anticancer drugs and also to increase the efficiency of current drug delivery systems, a pH and temperature-responsive polymeric nanogel was synthesized by copolymerization of N-vinylcaprolactam (VCL) and acrylic acid (AA) monomers (P(VCL-co-AA)) with a novel cross-linker, triethylene glycol dimethacrylate (TEGDMA), as a biocompatible and nontoxic component. The structural and physicochemical features of the P(VCL-co-AA) nanogel were characterized by FT-IR, DLS/Zeta potential, FE-SEM, and 1HNMR techniques. The results indicated that spherical polymeric nanogel was successfully synthesized with a 182 nm diameter. The results showed that the polymerization process continues with the opening of the carbon-carbon double bond of monomers, which was approved by C-C band removing located at 1600 cm-1. Doxorubicin (Dox) as a chemotherapeutic agent was loaded into the P(VCL-co-AA), whit a significant loading of Dox (83%), and the drug release profile was investigated in the physiological and cancerous site simulated conditions. P(VCL-co-AA) exhibited a pH and temperature-responsive behavior, with an enhanced release rate in the cancerous site condition. The biocompatibility and nontoxicity of P(VCL-co-AA) were approved by MTT assay on the normal human foreskin fibroblasts-2 (HFF-2) cell line. Also, Dox-loaded P(VCL-co-AA) had excellent toxic behavior on the Michigan Cancer Foundation-7 (MCF-7) cell line as model cancerous cells. Moreover, Dox-loaded P(VCL-co-AA) had higher toxicity in comparison with free Dox, which would be a vast advantage in reducing Dox side effects in the clinical cancer treatment applications.

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Ebrahimi, Rajabali, and Mahnoush Ebrahimi. "The stimuli-response characters of hydrogels prepared using ultrasound." Journal of Polymer Engineering 34, no. 7 (September 1, 2014): 625–32. http://dx.doi.org/10.1515/polyeng-2014-0028.

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Abstract The present work was an attempt to investigate the parameters that can affect the process of hydrogel formation in the presence of ultrasound. These parameters were concentrations of the reactants, the reaction medium, and acoustic factors. The monomers were acrylic acid and acrylamide, and the cross-linker was methylene bis acrylamide. Pulsed power ultrasound was irradiated to the reaction mixture from the tip of a probe unit. The swelling behaviors of the obtained hydrogels were investigated in various buffer solutions, at different temperature values, and using different ionic salts. The results show that ultrasonic irradiation significantly reduces reaction time and increases efficiency. Additionally, increasing glycerol in the solution changes the viscosity of the reaction for the better and increases the reaction rate. However, ionic strength and pH were not significantly effective in this respect. Another major finding was that increasing ultrasonic power and pulse hastens the reaction. Cationic salts were effective in this order: Na+>Ca2+>Fe3+. The hydrogel was responsive to pH, temperature, and salts. These findings provide a better understanding of hydrogel synthesis and enable us to control the pertinent parameters.

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Thambi, Thavasyappan, Jeongmin Lee, A.-Rum Yoon, Dayananda Kasala, and Chae-Ok Yun. "A pH- and Bioreducible Cationic Copolymer with Amino Acids and Piperazines for Adenovirus Delivery." Pharmaceutics 14, no. 3 (March 9, 2022): 597. http://dx.doi.org/10.3390/pharmaceutics14030597.

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Adenoviruses (Ads) are attractive nonviral vectors and show great potential in cancer gene therapy. However, inherent properties of Ads, including immunogenicity, nonspecific toxicity, and coxsackie and adenovirus receptor (CAR)-dependent cell uptake, limit their clinical use. To surmount these issues, we developed a pH- and glutathione-responsive poly(ethylene glycol)-poly(ꞵ-aminoester)-polyethyleneimine (PPA) for conjugation with Ad. The pH sensitivity of the PPA copolymer was elegantly tuned by substitution with different amino acids (arginine, histidine, and tryptophan), piperazines (Pip1, Pip2, and Pip3), and guanidine residues in the backbone of the PPA conjugate. PPA copolymer was further functionalized with short-chain cross-linker succinimidyl 3-(2-pyridyldithio)propionate) (SPDP) to obtain PPA-SPDP for facile conjugation with Ad. The PPA-conjugated Ad (PPA-Ad) conjugate was obtained by reacting PPA-SPDP conjugate with thiolated Ad (Ad-SH). Ad-SH was prepared by reacting Ad with 2-iminothiolane. The size distribution and zeta potential results of PPA-Ad conjugate showed an increasing trend with an increase in copolymer dose. From in vitro test, it was found that the transduction efficiency of PPA-Ad conjugate in CAR-positive cells (A549 and H460 cells) was remarkably increased at the acidic pH condition (pH 6.2) when compared with PPA-Ad conjugate incubated under the physiological condition (pH 7.4). Interestingly, the increase in transduction efficiency was evidenced in CAR-negative cells (MDA-MB-231 and T24 cells). These results demonstrated that biocompatible and biodegradable PPA copolymers can efficiently cover the surface of Ad and can increase the transduction efficiency, and hence PPA copolymers can be a useful nanomaterial for viral vector delivery in cancer therapy.

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Ren, Mingliang, Hui Li, Hu Liu, Lei Wang, Haibo Xiang, Xianrong Zhang, and Bin Yu. "A Biocompatible GdIII–Organic Framework Incorporating Polar Pores for pH-Sensitive Anti-Cancer Drug Delivery and Inhibiting Human Bone Tumour Cells." Australian Journal of Chemistry 72, no. 3 (2019): 233. http://dx.doi.org/10.1071/ch18268.

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With the aim of developing new and effective drug delivery systems for cancer treatments, great effort has been devoted to the field of porous metal–organic framework (MOF) platforms because of their controlled drug release performance, high drug loading, and acceptable biocompatibility. In this contribution, we report a MOF [Gd2(H2O)3(SDBA)3](DMA)3] (1, DMA=N,N-dimethylacetamide) with open O donor sites functionalised 1D pores, which has been fabricated using a bent polycarboxylic acid organic linker 4,4′-sulfonyldibenzoic acid (H2SDBA) under solvothermal conditions. Single crystal X-ray diffraction (SCRD), thermogravimetric analysis (TGA), elemental analysis, X-ray powder diﬀraction (XPRD), and Brunauer–Emmett–Teller (BET) analysis were used to characterise the as-prepared complex 1. 5-Fluorouracil (5-Fu) loaded 1 was soaked in phosphate buffer saline (PBS) and the invitro drug release performance was monitored by HPLC analysis under different pH conditions. At the pH values of 7.4 and 6.5, different profiles of pH-responsive release were achieved, indicating that the drug release performance of 5-Fu loaded 1 is pH sensitive. Grand Canonical Monte Carlo (GCMC) simulation results demonstrate that the open O donor sites in the framework of 1 account for the slower drug release rate. The prepared carrier is found to be bio-compatible with MG63 cells (cancerous tissue) and oral epidermal cells (normal tissue), when tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The 5-Fu loaded carrier also shows a promising growth inhibition effect towards the human bone tumour cells MG63.

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Bush, Joshua, Chih-Hsiang Hu, and Remi Veneziano. "Mechanical Properties of DNA Hydrogels: Towards Highly Programmable Biomaterials." Applied Sciences 11, no. 4 (February 21, 2021): 1885. http://dx.doi.org/10.3390/app11041885.

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DNA hydrogels are self-assembled biomaterials that rely on Watson–Crick base pairing to form large-scale programmable three-dimensional networks of nanostructured DNA components. The unique mechanical and biochemical properties of DNA, along with its biocompatibility, make it a suitable material for the assembly of hydrogels with controllable mechanical properties and composition that could be used in several biomedical applications, including the design of novel multifunctional biomaterials. Numerous studies that have recently emerged, demonstrate the assembly of functional DNA hydrogels that are responsive to stimuli such as pH, light, temperature, biomolecules, and programmable strand-displacement reaction cascades. Recent studies have investigated the role of different factors such as linker flexibility, functionality, and chemical crosslinking on the macroscale mechanical properties of DNA hydrogels. In this review, we present the existing data and methods regarding the mechanical design of pure DNA hydrogels and hybrid DNA hydrogels, and their use as hydrogels for cell culture. The aim of this review is to facilitate further study and development of DNA hydrogels towards utilizing their full potential as multifeatured and highly programmable biomaterials with controlled mechanical properties.

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Dragojevic, Sonja, Jung Su Ryu, Michael E. Hall, and Drazen Raucher. "Targeted Drug Delivery Biopolymers Effectively Inhibit Breast Tumor Growth and Prevent Doxorubicin-Induced Cardiotoxicity." Molecules 27, no. 11 (May 24, 2022): 3371. http://dx.doi.org/10.3390/molecules27113371.

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The anticancer agent doxorubicin(dox) has been widely used in the treatment of a variety of hematological malignancies and solid tumors. Despite doxorubicin’s efficiency in killing tumor cells, severe damage to healthy tissues, along with cardiotoxicity, limits its clinical use. To overcome these adverse side effects, improve patient safety, and enhance therapeutic efficacy, we have designed a thermally responsive biopolymer doxorubicin carrier that can be specifically targeted to tumor tissue by locally applying mild hyperthermia (41 °C). The developed drug vehicle is composed of the following: a cell penetrating peptide (SynB1) to promote tumor and cellular uptake; thermally responsive Elastin-like polypeptide (ELP); and the (6-maleimidocaproyl) hydrazone derivative of doxorubicin (DOXO-EMCH) containing a pH-sensitive hydrazone linker that releases doxorubicin in the acidic tumor environment. We used the in vivo imaging system, IVIS, to determine biodistribution of doxorubicin-delivered ELP in MDA-MB-231 xenografts in nude mice. Tumor bearing mice were treated with a single IV injection of 10 mg/kg doxorubicin equivalent dose with free doxorubicin, thermally responsive SynB1 ELP 1-DOXO, and a thermally nonresponsive control biopolymer, SynB1 ELP 2-DOXO. Following a 2 h treatment with hyperthermia, tumors showed a 2-fold higher uptake when treated with SynB1 ELP 1-DOXO compared to free doxorubicin. Accumulation of the thermally non-responsive control SynB1 ELP2 –DOXO was comparable to free doxorubicin, indicating that an increase in dox accumulation with ELP is due to aggregation in response to thermal targeting. Higher levels of SynB1 ELP1–DOXO and SynB1 ELP2 –DOXO with respect to free doxorubicin were observed in kidneys. Fluorescence intensity from hearts of animals treated with SynB1 ELP1–DOXO show a 5-fold decrease in accumulation of doxorubicin than the same dose of free doxorubicin. SynB1-ELP1-DOXO biopolymers demonstrated a 6-fold increase in tumor/heart ratio in comparison to free doxorubicin, indicating preferential accumulation of the drug in tumors. These results demonstrate that thermally targeted polymers are a promising therapy to enhance tumor targeting and uptake of anticancer drugs and to minimize free drug toxicity in healthy tissues, representing a great potential for clinical application.

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Kocak, G., C. Tuncer, and V. Bütün. "pH-Responsive polymers." Polymer Chemistry 8, no. 1 (2017): 144–76. http://dx.doi.org/10.1039/c6py01872f.

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Rajput, Rahul L., Jitendra S. Narkhede, Arun Mujumdar, and Jitendra B. Naik. "Synthesis and evaluation of luliconazole loaded biodegradable nanogels prepared by pH-responsive Poly (acrylic acid) grafted Sodium Carboxymethyl Cellulose using amine based cross linker for topical targeting: In vitro and Ex vivo assessment." Polymer-Plastics Technology and Materials 59, no. 15 (May 6, 2020): 1654–66. http://dx.doi.org/10.1080/25740881.2020.1759633.

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Dziarabina, Katsiaryna, Uliana Pinaeva, Sławomir Kadłubowski, Piotr Ulański, and Xavier Coqueret. "Radiolytic synthesis of gold nanoparticles in HEMA-based hydrogels: Potentialities for imaging nanocomposites." Nukleonika 66, no. 4 (November 25, 2021): 165–77. http://dx.doi.org/10.2478/nuka-2021-0025.

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Abstract This article reports on the radiolytic synthesis of nanocomposites containing gold nanoparticles (AuNPs) within two types of hydrogels based on 2-hydroxyethyl methacrylate (HEMA): (i) plain networks with various contents in ethylene glycol dimethacrylate (EGDMA), as a cross-linker and (ii) stimuli-responsive (SR) networks prepared from these monomers copolymerized with [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MADQUAT) to confer pH-switchable swelling. Hydrogels were prepared by photopolymerization with well-defined composition and a high degree of monomer conversion using two experimental procedures, as xerogels or in aqueous solution. Besides MADQUAT, acrylic acid (AA) or N-isopropylacrylamide have been tested as copolymers, yielding pHor temperature-sensitive hydrogels, respectively. Isothermal swelling in water was affected by monomer composition. Electron beam (EB) irradiation at doses up to 100 kGy of poly(HEMA) xerogels and water-swollen networks prepared with 0.5 wt% of EGDMA had a moderate impact on swelling characteristics and thermomechanical properties of the plain materials, whereas small amounts of extractables were formed. Poly(HEMA)-based nanocomposites containing AuNPs were successfully obtained by EB irradiation of samples swollen by aqueous solutions of Au(III). The effects of dose and cross-linking density on the formation of AuNPs were monitored by UV-visible spectroscopy. Irradiation at well-defined temperatures of the Au(III)-loaded SR hydrogels induced the formation of nanoparticles with size-dependent features, whereas the efficiency of Au(III) reduction at 10 kGy was not significantly affected by the network structure. EB-induced reduction of Au(III) in poly(HEMA) hydrogels using a lead mask to generate well-defined patterns yielded coloured and long-lasting images in the zones where the nanocomposite was formed.

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Okada, Satoshi, Satoko Takayasu, Shunsuke Tomita, Yoshio Suzuki, and Shinya Yamamoto. "Development of Neutral pH-Responsive Microgels by Tuning Cross-Linking Conditions." Sensors 20, no. 12 (June 14, 2020): 3367. http://dx.doi.org/10.3390/s20123367.

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Polymer microgels that respond in a range of neutral pH can be useful for the development of molecular imaging tools and drug-delivery carriers. Here, we describe a simple approach in developing microgels that undergo volume phase transitions and substantial nuclear magnetic resonance (NMR) relaxometric changes within a narrow pH range of 6.4 to 7.4. The pH-responsive microgels were synthesized using methacrylic acid and a series of ethylene glycol dimethacrylate cross-linkers with repeating units of ethylene glycol that range from one to four. NMR relaxometry demonstrated that the transverse relaxation time (T2) of a suspension containing microgels that were cross-linked with diethylene glycol dimethacrylate sharply decreases at the pH where volume phase transition occurs. The polymer microgels cross-linked with 40 and 45 mol% of diethylene glycol dimethacrylate caused about 50% T2 reduction with decreasing pH from 6.8 to 6.4. These results demonstrated that responses of microgels to a range of neutral pH can be easily tuned by using appropriate cross-linkers with certain cross-linking degree. This approach can be useful in developing highly sensitive molecular sensors for magnetic resonance imaging (MRI) of tissue pH values.

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Guo, Chang, Suying Xu, Anila Arshad, and Leyu Wang. "A pH-responsive nanoprobe for turn-on 19F-magnetic resonance imaging." Chemical Communications 54, no. 70 (2018): 9853–56. http://dx.doi.org/10.1039/c8cc06129g.

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Weaver, Jonathan V. M., and Dave J. Adams. "Synthesis and application of pH-responsive branched copolymer nanoparticles (PRBNs): a comparison with pH-responsive shell cross-linked micelles." Soft Matter 6, no. 12 (2010): 2575. http://dx.doi.org/10.1039/b926796d.

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Long, Yu-Bo, Wen-Xing Gu, Chengcai Pang, Jianbiao Ma, and Hui Gao. "Construction of coumarin-based cross-linked micelles with pH responsive hydrazone bond and tumor targeting moiety." Journal of Materials Chemistry B 4, no. 8 (2016): 1480–88. http://dx.doi.org/10.1039/c5tb02729b.

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Yu, Yueqin, Xianzhi Chang, Hansheng Ning, and Shusheng Zhang. "Synthesis and characterization of thermoresponsive hydrogels cross-linked with chitosan." Open Chemistry 6, no. 1 (March 1, 2008): 107–13. http://dx.doi.org/10.2478/s11532-007-0065-1.

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AbstractHydrogels composed of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) were prepared by redox polymerization with degradable chitosan cross-linkers. Chitosan degradable cross-linkers were synthesized by the acrylation of the amine groups of glucosamine units within chitosan and characterized with 1H NMR. With the chitosan cross-linkers, loosely cross-linked poly(N-isopropylacryamideco-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels were prepared, and their phase transition behavior, lower critical solution temperature (LCST), water content and degradation properties were investigated. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels were pliable and transparent at room temperature. The LCST could be adjusted at 32∼39°C by alternating the feed ratio. Swelling was influenced by NIPAAm/AAc monomer ratio, cross-linking density, swelling media, and temperature. All hydrogels with different feeding ratios contained more than 95% water at 25°C in the ultra pure water and phosphate-buffered saline (PBS, pH = 7.4 ± 0.1), and had a prospective swelling in the simulated gastric fluids (SGF, pH = 1.2) > 72.54%. In degradation studies, breakdown of the chitosan cross-linked P(NIPAAm-co-AAc) hydrogels was dependent on the cross-linking density. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels which can be tailored to create environmentally-responsive artificial extracellular materials have great potential for future use.

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Li, Yali, Wenjun Du, Guorong Sun, and Karen L. Wooley. "pH-Responsive Shell Cross-Linked Nanoparticles with Hydrolytically Labile Cross-Links." Macromolecules 41, no. 18 (September 23, 2008): 6605–7. http://dx.doi.org/10.1021/ma801737p.

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Journal articles on the topic 'PH-responsive linker'

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