Academic literature on the topic 'Hemoglobin Confinement'

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Journal articles on the topic "Hemoglobin Confinement"

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Siddiqui, Gufran Ahmed, and Aabgeena Naeem. "Refolding of Hemoglobin Under Macromolecular Confinement: Impersonating In Vivo Volume Exclusion." Journal of Fluorescence 31, no. 5 (June 22, 2021): 1371–77. http://dx.doi.org/10.1007/s10895-021-02751-y.

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Samajdar, Rudra N., Gitanjali Asampille, Hanudatta S. Atreya, and Aninda J. Bhattacharyya. "Hemoglobin Dynamics in Solution vis-à-vis Under Confinement: An Electrochemical Perspective." Journal of Physical Chemistry B 124, no. 28 (June 18, 2020): 5771–79. http://dx.doi.org/10.1021/acs.jpcb.0c02372.

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Ahmed, Ahmed O., Isam M. Abdallah, Ibrahim A. Ali, and Omer A. Musa. "Effect of police training during the confinement period on some cardiopulmonary and hematological parameters in Khartoum, Sudan." International Journal of Research in Medical Sciences 6, no. 5 (April 25, 2018): 1639. http://dx.doi.org/10.18203/2320-6012.ijrms20181751.

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Background: Pulmonary function tests (PFT) serve as a tool of health assessment and as a predictor of occupational fitness. Police officers must develop and maintain high levels of physical fitness for physical demanding tasks they perform. The training program starts with confinement of five to eight weeks according to the trainee. Previously it has been shown that the police students have better lung functions values compared to their civilian colleagues. In this study the effect of the confinement training on pulmonary function tests was investigated.Methods: Eighty one policemen trainee were randomly selected from a new batch in the faculty of police sciences and Law, the National Ribat University, Khartoum, Sudan at their starting confinement period. Subjects were medically fit with no history of Diabetes, Hypertension, Asthma or use of any long term medications. Pulmonary function tests (FVC, FEV1 and PEFR) were performed using a micro-plus spirometer. Blood pressure, pulse rate, and hemoglobin were measured. All these were repeated at the end of the confinement.Results: The age of participants ranged from 24 to 26 years. FVC, FEV1 and PEFR significantly increased after the confinement period. The blood pressure and the pulse significantly decreased. The weight of the participants decreased after the confinement but Hb significantly slightly increased.Conclusions: Regular police training during the confinement improved the pulmonary and cardiovascular reserve function.
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Mandal, Soumit S., Brindha Nagarajan, H. Amenitsch, and Aninda J. Bhattacharyya. "Probing hemoglobin confinement inside submicron silica tubes using synchrotron SAXS and electrochemical response." European Biophysics Journal 42, no. 5 (January 29, 2013): 371–82. http://dx.doi.org/10.1007/s00249-013-0886-0.

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Nordi, W. M., K. C. E. Yamashiro, M. Klank, R. Locatelli-Dittrich, R. N. Morais, A. I. Reghelin, and C. F. M. Molento. "Quail (Coturnixcoturnix japonica) welfare in two confinement systems." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 64, no. 4 (August 2012): 1001–8. http://dx.doi.org/10.1590/s0102-09352012000400029.

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The intensification of animal production systems presents a potential impact on the welfare of animals. The objective of this work was to assess the welfare of quail Coturnixcoturnix japonicain two maintenance systems: battery cages (BC),and enriched aviary (EA),with saw-dust bedding, sand-bathing area and nests. The experiment procedure involved eight animals per holding area and four repetitions per treatment, an overall of 64 quails. Welfare was assessed through behavioral freedom, sanitary freedom (feather condition and injuries), blood analyses and glicocorticoid metabolites measurement in droppings. Results are presented in the BC order, followed by EA. Water drinking behavior and agonistic behavior were different between treatments (P<0.05). Feather condition was adequate in both treatments, except for the head in BC quails. Blood data were statistically different forred blood cells, hematocrit, hemoglobin, blood proteins, eosinophils, heterophils, lymphocytes and heterophil: lymphocyte ratio. Glicocorticoid metabolites levels were significantly different between maintenance systems. The behavioral and physiological welfare indicators showed higher welfare degree for quails in enriched aviary as compared to battery cages system.
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Habib, Md Ahasan. "A Refractive Index Based Micro-Structured Sensor for Blood Components Detection in Terahertz Regime." Sensor Letters 18, no. 1 (January 1, 2020): 74–82. http://dx.doi.org/10.1166/sl.2020.4186.

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In this article, a hexagonal packing photonic crystal fiber based optical sensor is presented and analyzed for different blood components identification using terahertz (THz) signal. The numerical analysis of the proposed sensor is performed by using finite element method based software Comsol V5.0. The proposed fiber is investigated in terahertz frequency spectrum from 1.3 THz to 2.5 THz for higher relative sensitivity and numerical aperture as well as lower absorption loss and confinement loss for better sensing applications. The reported hollow core fiber provide better interaction of light and the analytes, so that high relative sensitivity of 83.45%, 81.20%, 80.78%, 79.60% and 78.80% are obtained for RBCs, Hemoglobin, WBCs, Plasma and Water respectively at a particular geometric condition. Moreover, very low confinement loss and absorption loss with high numerical aperture is offered by the proposed sensor in terahertz spectrum. This optical sensor may be an alternative option to detect blood components present in the blood in a very efficient manner.
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Shu, Yang, Lu Han, Xiaofeng Wang, Xuwei Chen, and Jianhua Wang. "Fluorescence Enhancement of Imidazolium Ionic Liquid by Its Confinement on PVC for In Situ Selective Quantification of Hemoglobin." ACS Applied Materials & Interfaces 5, no. 22 (November 12, 2013): 12156–62. http://dx.doi.org/10.1021/am404069f.

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Di Riso, Daniela, Simone Bertini, Silvia Spaggiari, Francesca Olivieri, Silvana Zaffani, Lara Comerlati, Marco Marigliano, Claudia Piona, and Claudio Maffeis. "Short-Term Effects of COVID-19 Lockdown in Italian Children and Adolescents with Type 1 Diabetes Mellitus: The Role of Separation Anxiety." International Journal of Environmental Research and Public Health 18, no. 11 (May 22, 2021): 5549. http://dx.doi.org/10.3390/ijerph18115549.

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In March 2020, the Italian Government imposed mandatory home confinement to limit the spread of COVID-19. Few studies assessed the psychophysical impact of COVID-19 on chronically ill children. This study examined these effects on children with Type 1 Diabetes Mellitus (T1D) and their caregivers. Seventy-one patients (7–13 years) with T1D and their caregivers were administered a survey created ad hoc and some standardized questionnaires, assessing psychological well-being and anxiety. Medical data (physical and biochemical characteristics) were recorded before (T0, January–February) and after (T1, May–June) the lockdown. Paired Student t-test, Spearman two-tailed correlations, and a linear regression model were used for statistical analysis. Children at T1 showed higher BMI (body mass index), daily total and basal insulin dose, and time spent in therapeutic range, and they showed lower HbA1c (glycated hemoglobin), time spent above the therapeutic range, and standard deviations of the mean glucose values than at T0. A total of 32.9% scored in the clinical range for separation anxiety. The increase in separation anxiety was predicted by younger age, female gender, more recent T1D diagnosis, less time spent in therapeutic range at T1, and higher perceived fear of COVID-19 infection. In a pandemic context, separation anxiety may be stronger in younger females, with more recent T1D diagnosis and poor metabolic control, thus affecting the parent’s ability to manage diabetes and to support children’s autonomy.
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Mukhopadhyay, Partha, Tara Sankar Bag, Amit Kyal, Dipta Prasun Saha, and Noori Khalid. "Oral Hypoglycemic Glibenclamide: Can it be a Substitute to Insulin in the Management of Gestational Diabetes Mellitus? A Comparative Study." Journal of South Asian Federation of Obstetrics and Gynaecology 4, no. 1 (2012): 28–31. http://dx.doi.org/10.5005/jp-journals-10006-1167.

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ABSTRACT Introduction Gestational diabetes is a common medical disorder in pregnancy. So long, it has been usually treated by insulin. Now it has been found that oral glibenclamide can be used instead of insulin with similar glycemic control and without any adverse maternal and fetal effect. Methods A comparative study between oral glibenclamide and insulin for the management of gestational diabetes mellitus (GDM) was conducted. It was a prospective randomized study and patients attending the antenatal clinic were screened with 75 gm oral glucose between 20 to 28 weeks and GDM was diagnosed based on WHO criteria of 2 hours blood glucose ≥140 mg/dl. Women with gestational diabetes were given medical nutritional therapy (MNT) for 2 weeks. Out of this, 60 women did not achieve the target blood glucose. The goal of treatment was maintenance of mean plasma glucose (MPG) of about 105 mg%. For this the fasting plasma glucose should be around 90 mg/dl and postprandial peaks around 120 mg/dl. Patients were randomly assigned to receive glibenclamide (group A, n = 30) or insulin (group B, n = 30). In group A, glibenclamide was given 2.5 mg orally in morning and doses were increased weekly by 2.5 mg up to a maximum of 20 mg and doses >7.5 mg were given in two divided doses. In group B, insulin 0.7 units per kilogram of body weight at admission was given subcutaneously three times daily and increased weekly as necessary. Self monitoring of blood glucose with glucometer was done. Blood glucose was also measured from the laboratory every week. Glycosylated hemoglobin (HbA1c) was measured before initiation of therapy and repeated in the third trimester before confinement. Terminations of pregnancy in both the groups were done between 37 and 38 weeks. The infant birth weight, blood glucose and serum bilirubin were also recorded in all cases. Results The present study showed that the two groups had similar glycemic status (fasting blood sugar in group A was 103.5 ± 14.62 mg/dl and postprandial blood sugar was 184.1 ± 20.46 mg/dl whereas in group B it was109.3 ± 19.63 mg/dl and 194.3 ± 18.47mg/dl) at the time of entry into the study. The two groups also showed similar levels of glycemic control just before confinement (fasting blood sugar in group A was 88.23 ± 6.55 mg/ dl and postprandial blood sugar was 122.7 ± 10.3 mg/dl whereas in group B it was 88.17 ± mg/dl and 128 ± 12.38 mg/dl) and there was no significant statistical difference in the two groups (p > 0.05). The perinatal outcomes in both the groups were also nearly same. There was no significant difference in birth weight, blood sugar level of neonates and complications between the two groups. There was no case of macrosomia in the two groups and the number of infants large for gestational age (LGA) was four in group A and two in group B. Hypoglycemia in newborn was slightly higher in the group A compared to group B (4 and 3 respectively). Conclusion From our study, it is evident that the use of oral agents is a pragmatic alternative to insulin therapy in cases of gestational diabetes because of similar glycemic control, ease of administration and better patient compliance due to noninvasive treatment. How to cite this article Mukhopadhyay P, Bag TS, Kyal A, Saha DP, Khalid N. Oral Hypoglycemic Glibenclamide: Can it be a Substitute to Insulin in the Management of Gestational Diabetes Mellitus? A Comparative Study. J South Asian Feder Obst Gynae 2012;4(1):28-31.
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Yacoub, Abdulraheem, Omar S. Aljitawi, and Wei Cui. "Primary Bone Marrow DLBCL, Unraveling The Unique Biology Of This Very Rare Presentation." Blood 122, no. 21 (November 15, 2013): 5065. http://dx.doi.org/10.1182/blood.v122.21.5065.5065.

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Abstract Introduction Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) accounting for approximately 25 percent of NHL cases. It is increasingly appreciated that the diagnostic category of DLBCL is quite heterogeneous in terms of morphology, genetics, and biologic behavior. Patients with DLBCL typically present with a rapidly enlarging lymph node. Extra nodal disease can also occur anywhere in the body and usually denotes an advanced stage. Approximately 60 percent of patients will present with advanced stage DLBCL (stage III or IV disease). The bone marrow (BM) involvement, as a part of systemic multifocal disease, at presentation is 8-10%, but can be up to 30% during the course of the disease, especially if discordant histologic subtypes, such as follicular lymphoma, are included. BM involvement is a negative prognostic factor of DLBCL despite modern therapy. Primary bone marrow lymphoma (PBML) is a very rare entity in which clinicobiological significance is not well defined, but perceived to represent a particularly poor-risk subclass. Herein, we present a case of primary bone marrow DLBCL and try to explore the unique presentation based on DLBCL-bone marrow microenvironment interactions. Cadherins, for example, are transmembrane proteins that play important roles in cell adhesion and are recently recognized as a component of myeloma and leukemia-bone marrow microenvironment interactions. We hypothesized that DLBCL cells would express N-cadherin. In this study, we evaluated E -cadherin and N-cadherin expression in BM samples from this patient. Case description A 77-year-old presented with progressive fatigue, and rapidly developed pancytopenia with transfusion dependence over 3 months. He had no bone pain or B symptoms at presentation. Clinical examination revealed pallor, but no lymph node enlargement or abdominal organomegaly. His hemoglobin was 5.7 g/dL, Platelets 29 X103/µL, and absolute neutrophil count 800/ µL. LDH was elevated at 444 UL. A BM aspirate was a dry tap, BM biopsy showed hyper cellular marrow (90-100%), and greater than 90% involvement by malignant lymphocytes that were positive for CD20, CD79a, Pax5, CD45, NSE, Mum1, and vimentin. Only 5% Mib1 proliferation index was appreciated on the biopsy specimen, probably due to decalcification effect. There was moderately increased reticulin fibrosis. The morphologic and immunophenotypic features were consistent with DLBCL. Cytogenetic studies showed a complex near-triploid abnormal clone. FISH analysis showed no evidence of MYC rearrangement, t(14;18), or t(11;14). PET-CT scan showed marked increase in metabolic activity diffusely involving the axial skeleton but no metabolically active lymphadenopathy or extramedullary disease, no destructive or lytic lesions were found [Fig.1]. Immunohistochemistry stains showed strong N-cadherin staining the malignant cells [Fig.2]. E-cadherin staining was negative. The patient was treated with 6 cycles of R-CHOP. Doxorubicin dose was reduced due to advanced age. His post-treatment BM biopsy and PET scan were consistent with complete response. BM fibrosis significantly decreased [Fig. 3]. His cytopenias completely corrected early during therapy. Discussion Criteria to diagnose PBML encompass isolated bone marrow infiltration, with no evidence of nodal or extranodal involvement, including the bone, and the exclusion of leukemia/lymphomas that are considered to primarily involve the bone marrow. In a retrospectively reviewed by the International Extranodal Lymphoma Study Group from 12 institutions in 7 different countries over a 25-year period, there were only 15 cases of DLBCL that met these criteria. The biology behind the exclusive confinement to the BM compartment remains elusive. On further analysis of this case, E-cadherin was negative. Expression of the adhesion molecule marker N-cadherin on lymphoma cells might help explain the confinement to the BM microenvironment in our case. Future studies should focus on exploring the role of N-cadherin in this rare entity of DLBCL. Disclosures: No relevant conflicts of interest to declare.
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Dissertations / Theses on the topic "Hemoglobin Confinement"

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Mandal, Soumit Sankar. "A Few Applications of Porous Materials in Biology and Environment." Thesis, 2013. https://etd.iisc.ac.in/handle/2005/4576.

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The present thesis discusses the beneficial effects of confining biologically relevant molecules inside porous structures of varying morphology and dimensions. Confinement of a biomolecule such as protein, enzymes drugs leads alteration in structural features and to a significant improvement in its biophysical properties. These properties include electrochemical redox behavior (for electroactive biomolecules) and thermal stability (denaturation temperature) of the concerned biomolecule. Silica (SiO2) based materials were primarily used as substrates for confining proteins and drugs. The confinement effects were probed in depth using various electrochemical, spectroscopic, and scattering techniques. The outcomes of confinement were utilized for developing electrochemical biosensors for the protein detection. Confinement of drugs effects their structural properties which gets reflected in their release kinetics studies. Electrochemical sensing was carried out using porous structure modified electrodes. These were used not only for detection of biological analytes but also extended to environmental pollutants. In the thesis, Chapters 2-4 deal with discussions related to electrochemical, spectroscopic, and scattering studies of protein confined inside SiO2 as well as polymer capsules. In Chapter 5A and 5B, Titania (TiO2) based nanotubes were utilized for demonstration of realistic electrochemical biosensors for the detection of myoglobin and a penicillin binding protein. In Chapters 6 and 7, enzyme and inhibitors, drug release kinetics from mesoporous oxides and TiO2 tubes have been discussed. Using the same approach as in chapter 5, electrochemical sensing of model environmental pollutants using TiO2 microwires have been discussed in chapters 8A and B. The use of TiO2 microwires for photocatalytic applications have also been considered in detail. A brief discussion of the contents and highlights of the individual chapters are described below: Chapter 1 discusses in detail about the porous substrates extensively used for biomolecular (proteins and drugs) confinement and structural features of these substrates. These substrates include the mesoporous materials of varying pore dimensions and pore arrangement. The alteration in the biophysical properties of the molecules because of confinement within these mesoporous substrates and its effects on related applications such as bio catalysis, drug release rates, electrochemical biosensing have been considered. A brief discussion on the present state of art in the field of drug delivery, enzyme catalysis and electrochemical biosensing have been included. The principles related to electrochemical, spectroscopic and the scattering techniques used to characterize the properties have been discussed in detail in this chapter. Chapter 2 include discussions on the investigations on the structure and function of hemoglobin (Hb) confined inside sol-gel template synthesized silica tubes (SiO2-tubes) Immobilization of hemoglobin inside SiO2-tubes resulted in the facile electron transfer to electroactive heme center leading to an enhanced electrochemical response. The consequences of confinement on protein structures and activity were further probed via ligand binding and thermal stability studies. Reversible binding of n-donor liquid ligands such as pyridine and its derivatives and predictive variation in their redox potentials were obtained from detailed electrochemical investigations. The results suggested absence of adverse effect on structure and function of Hb confined inside the channels of SiO2-tubes. Additionally, the thermal stability of confined Hb was compared to that of free Hb in solution. The melting or denaturation temperature of Hb immobilized inside SiO2-tubes increased by approximately 4 oC compared to that of free Hb. In Chapter 3A, the configuration of hemoglobin (Hb) in solution and confined inside silica tubes (SiO2-tubes) have been studied using synchrotron small angle x-ray scattering (SAXS) and the consequences were correlated to its electrochemical activity. Confinement inside silica tubes aided in preventing protein aggregation compared to that observed for unconfined protein in solution. In case of confined Hb, the radius of gyration (Rg) and size polydispersity (p) was considerably lower than in solution. The difference in configuration between the confined and unconfined protein were reflected in their electrochemical response. Reversible electrochemical response (from cyclic voltammograms) were obtained in case of the confined hemoglobin in contrary to only cathodic response for the unconfined protein in solution. This led to the conclusion of difference in orientation of the electroactive heme center. The electron transfer coefficient () and electron transfer rate constant (ks) were also calculated to further support the structural differences between the unconfined and confined states of the hemoglobin. Thus, absence of any adverse effects on confinement of proteins inside the inorganic matrices such as silica nanotubes opens new prospects for utilizing inorganic matrices as protein “encapsulators” as well as sensors at varying temperatures. Chapter 3B discusses the implications of host dimensions on the protein structure. This is a very important parameter as it considerably influences the protein properties under confinement. This study probes the structure of same Hb molecules, confined inside silica tubes of pore diameters varying by one order in magnitude: ~ 20-200 nm. The confinement effect on structure was probed vis-à-vis the protein in solution. Small angle neutron scattering (SANS), which provides information on the protein tertiary and quaternary structures, was employed to study the influence of tube pore diameter on confined protein structure and configuration. Depending on the SiO2-tubes pore diameter, confinement significantly influenced the structural stability of Hb. High radius of gyration (Rg) and polydispersity (p) of Hb in case of the 20 nm diameter SiO2-tubes indicated that Hb undergoes significant amount of aggregation. However, for SiO2-tubes with pore diameters > 100 nm, Rg of Hb was found to be in very close proximity to that obtained from the protein data bank (PDB) reported structure. This strongly indicated that the protein has a preference for the more native like non-aggregated state when confined inside tubes of diameter ~ 100 nm. Further insight in to the Hb structure was obtained from distance distribution function, p(R) and ab-initio models calculated from the SANS patterns. These also suggest that the size of SiO2-tubes is a key parameter for the protein stability and structure. In Chapter 4 we have introduced an organic substrate to investigate the effect of confinement on structure of hemoglobin (Hb). Like as discussed in chapters 3(A and B), Hb transformed from an aggregated state in solution to non-aggregated state when confined inside the polymer capsules. Synchrotron small angle x-ray scattering (SAXS) studies directly confirmed this fact. The radius of gyration (Rg) and polydispersity (p) of the proteins in the confined state were smaller compared to that in solution. In fact, the Rg value was very similar to theoretical values obtained using protein structures generated from protein databank. The Rg value was almost constant in the temperature range (25-85 °C, Tm = 59 °C), for the confined Hb. This observation is in contrary to the increasing Rg values obtained for the free Hb in solution suggesting higher thermal stability of confined Hb inside the polymer capsule. Protein functions gets significantly altered as a result this. It resulted in an enhancement of the electroactivity of confined Hb. While Hb in solution showed dominance of the cathodic process (Fe3+→ Fe2+), efficient reversible Fe3+/Fe2+ redox response is observed in case of the confined Hb. This again gave an indication of the difference in orientation of electroactive heme group resulting it to reside in a chemically different environment compared to when it is in solution. This has important implications on protein functional properties and related applications. Thus, in this chapter we get a detailed overview of how confinement orients different groups’ viz., electroactive heme center to take up positions that makes it favorable to participate in biochemical activities such as sensing of analytes from small to macromolecules and controlled delivery of drugs. The conclusions derived from the studies in previous chapters have been utilized in chapters 5A and 5B for developing a realistic electrochemical biosensor. Since the sensing based on electrochemical response largely depends on the location of heme group, the location of the heme center was altered in a controlled manner using chemical treatment. Chapter 5A deals with an alternate antibody-free strategy for the rapid electrochemical detection of cardiac myoglobin (having heme center) using hydrothermally synthesized TiO2 nanotubes (TiO2-NT). In this strategy, myoglobin was unfolded using denaturants to expose deeply buried electroactive heme center into the solution very close to the electrode. This leads to an efficient reversible electron transfer from protein to electrode surface. The sensing performance of the TiO2-NT modified electrodes were compared vis á vis commercially available titania and GCE electrodes. The tubular morphology of the TiO2-NT led to facile transfer of electrons to the electrode surface which eventually provided linear current response (obtained from cyclic voltammetry) over a wide range of Mb concentration. The sensitivity of the TiO2-NT based sensor was remarkable and was equal to 18 A/ mg ml-1 (detection limit= 50 nM). This coupled with the rapid analysis time of few tens of minutes (compared to few days for ELISA) demonstrates its potential usefulness for the early detection of the acute myocardial infarction (AMI). Chapter 5B comprises of a discussion of employing a rapid electrochemical detection method of proteins without any electroactive center. The protein was transformed to an electrochemically active protein via metal tagging (Fe3+ in this case). This biosensor was also based on titania (TiO2-NT) nanotubes which was used to modify the working electrode. To reduce the detection volumes drastically, screen printed carbon electrodes (SPCE) was introduced in this detection. It was possible to detect as low as 1 ng l-1 of protein in very small sample volumes (as low as 30 l). The feasibility of this method for the detection of PBP2a, a marker for methicillin resistant Staphylococcus aureus (MRSA) was demonstrated here. This biosensor could effectively detect PBP2a in whole cell lysate samples. To mimic the practical detection conditions, the selectivity and efficiency was also validated using other non-selective proteins such as PTP10D, a protein tyrosine phosphatase, and bovine serum albumin (BSA). As already mentioned, this electrochemical detection strategy could reproducibly detect protein samples within minutes compared to standard ELISA methods (3-4 h) or a modified ELISA protocols (FAST-ELISA; 30 mins) excluding the time taken for sample preparation. These observations suggest the potential of the titania nanotube based electrochemical biosensor in both clinical and community settings for the detection of infectious pathogen In Chapter 6, the feasibility of utilizing mesoporous matrices of alumina and silica for inhibition of enzymatic activity have been presented. These studies were performed on a protein tyrosine phosphatase by the name chick retinal tyrosine phosphotase-2 (CRYP- 2), a protein that is identical in sequence to the human glomerular epithelial protein-1 and involved in hepatic carcinoma. The inhibition of CRYP-2 is of tremendous therapeutic importance. Inhibition of catalytic activity was examined using the sustained delivery of para nitrocatechol sulfate (pNCS) from bare and amine functionalized mesoporous silica (MCM-48) and mesoporous alumina (Al2O3). Amine functionalized MCM-48 was found to exhibit the best release of pNCS among the various mesoporous matrices studied and hence inhibition of CRYP-2 was maximum in this case. The maximum speed of reaction, vmax (= 160 ± 10 μmols min-1mg-1) and inhibition constant, Ki (= 85.0 ± 5.0 μmols) estimated using a competitive inhibition model were found to be very similar to inhibition activities of protein tyrosine phosphatases using other methods. In Chapter 7, we have demonstrated another very attractive application of the TiO2-NT which have been already used for protein sensing application. Due to the porous nature of the surface and its other attractive features, TiO2-NT has a great potential in drug delivery applications. The TiO2-NT mimicked the pore channels of the mesoporous substrates that have been used in the previous chapter. The drug release from these TiO2- NT exhibited a completely different sigmoidal release profile compared to our previous reports from the group. Additionally, the effect of surface functionalization and solution pH on drug release profile have also been considered during our studies. The release profiles were modelled with theoretical Hill equation to extract several physical parameters to explain the extent of drug substrate interactions. These results further supplemented the unique nature of the release profile. In Chapter 8A we have again demonstrated an electrochemical detection strategy but this time for chemical pollutants. Commercial textile industry effluents such as dyes were chosen for the model studies. Mesoporous anatase titania microwires synthesized via an optimized polyol method were used for sensing and photocatalysis of these dyes. Using spectroscopic investigations, we have showed that these titania microwires preferentially sense cationic (e.g. methylene blue, Rhodamine B) over anionic (e.g. Orange G, Remazol Brilliant Blue R) dyes. It was observed that variation in microwire dimensions and pH of dye solution, led to an increase in the concentration of the adsorbed dye. These findings were later corroborated with much faster electrochemical sensing. The effect of microwire length on electrochemical detection sensitivity have also been accounted in these studies. The photochemical performance of these titania microwires have been compared with the commercial P25-TiO2 nano powders. The photochemical performance was also studied as a function of exposure times and pH of dye solution. Excellent sensing ability and photocatalytic activity of the titania microwires was attributed to increased effective reaction area of the controlled nanostructured morphology. This makes them an attractive substrate for commercial sensing applications In Chapter 8B, anatase TiO2 microwires used in previous chapter were chemically modified to silver (Ag) decorated TiO2 microwires (Ag-TiO2). This was done with an aim to improve the detection sensitivity and photodegradation performance. The Ag-TiO2 microwires were synthesized via polyol synthesis route followed by a simple surface modification and chemical reduction approach for attachment of silver. The electrochemical sensing performance of Ag-TiO2 microwires have been subsequently compared with the base TiO2 microwires in the detection of cationic dye such as methylene blue. The superior performance of the Ag-TiO2 composite microwires was attributed to improved surface reactivity, mass transport and catalytic property because of decorating the TiO2 surface with Ag nanoparticles. Further studies were also carried out to compare its photocatalytic activity with TiO2 microwires at constant illumination protocols and observation times. As demonstrated the improved photocatalytic performance of Ag-TiO2 composite microwires was attributed to the formation of a Schottky barrier between TiO2 and Ag nanoparticles leading to a fast transport of photogenerated electrons to the Ag nanoparticles.
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Bradu, Adrian. "Methodes Optiques d'exploration des tissus biologiques. Spectrometrie des tissus cerebraux au moyen des sondes miniatures a fibres optiques et imagerie par Tomographie Optique Coherente." Phd thesis, 2004. http://tel.archives-ouvertes.fr/tel-00007180.

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Nous abordons dans ce memoire deux methodes d'exploration des tissus biologiques. Premierement nous presenterons une technique spectroscopique invasive d'investigation des tissus cerebraux profonds. Cette technique utilisant des sondes optiques en miniature tire partie de la forte retrodiffusion de la lumiere par les tissus biologiques. Ainsi, l'attenuation lumineuse qu'on mesure experimentallement contient des informations non seulement sur les proprietes de diffusion mais aussi sur les concentrations des chromophores qu'ils contiennent. Le resultat est la posibilite d'envisager la mise en oeuvre d'une methode d'observation directe de certains paramatres hemodynamiques dont la saturation tissulaire en oxygene ou la concentration en hemoglobine totale. Deuxiemement nous presenterons une methode d'imagerie des tissus biologiques en particulier de l'oeil: la tomographie optique coherente. Sa technique tire partie de proprietes de coherence de la lumiere. Ainsi, l'interference constructive des faisceux lumineux provenant de deux bras d'un interferometre de type Michelson donne naissance a un signal contenant des informations sur la reflectivite provenant d'un domaine spatial de la cible limite par la longueur de coherence de la source. En utilisant ces bases theoriques nous avons mis en oeuvre un system OCT rapide utilisant un scanner resonant.
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