Estimation of micropolarity and microfluidity at the water-polymer interface is important in understanding the physicochemical behavior of polymeric gels in the context of their wide biomedical applications. In this work, fluorescence studies of 8-Anilino-1-naphthalene-sulphonate (ANS) were used to introduce a new microviscosity parameter. Z and ET(30) solvent polarity scales were found to work well in resolving the polarity differences in various polyacrylamide gel compositions. A microviscosity parameter τη is an easy-to-estimate parameter that was used to follow the changes in microviscosity with changes in polymer composition. The microviscosity parameter could efficiently estimate the increase of microviscosity with increase in the crosslinker, as well as initiator concentrations at the same monomer concentration. © 2013 Springer Science+Business Media Dordrecht.

Ashok Kumar Mishra

Department Of Chemistry

Biomedical applications

Fluorescence studies

INITIATOR CONCENTRATION

MICRO-POLARITY

MICROHETEROGENOUS MEDIUM

Microviscosities

Monomer concentration

PHYSICOCHEMICAL BEHAVIORS

Estimation

Fluorescence

Medical applications

naphthalene

Polymers

Solvents

Functional polymers

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Polymer Research

Glucose triazole cardanol conjugate (GTHCC) is a supergelator in water-methanol (1:1) solvent mixture. Environmental scanning electron microscopy (ESEM) and fluorescence molecular probe based techniques were employed to understand the thermotropic gelation induced changes in micropolarity and microviscosity of GTHCC hydrogel in water-methanol (1:1) solvent mixture. ESEM analysis has shown the formation of spongy sheet like structures having micrometer size pores inside it. The fluorescence intensity and fluorescence anisotropy measurements of the polarity sensitive probe 8-anilino-1-naphthalene sulfonic acid (ANS) revealed a significant increase in the micropolarity and a significant decrease in the microviscosity of GTHCC hydrogel between the gel and sol phases. Time resolved fluorescence decay analysis of ANS has shown the presence of two different microenvironments in the system and thermotropic microenvironmental changes between gel and sol phases of GTHCC hydrogels. © 2014 The Royal Society of Chemistry.

Fulltext

RSC Advances

Thermotropic gelation induced changes in micropolarity and microviscosity of hydrogel derived from glucose-triazole-hydrogenated cardanol conjugate: A study using fluorescent molecular probe

Many ailments and/or malfunctions of the body have been observed to change the viscous behavior and elastic properties of biological soft tissues. The technique of elastography has evolved to image such properties. The clinical evidence gathered during studies involving elastography to identify cancerous lesions is very promising. However, the quantification of the resolution and specificity of elastography is best achieved under a controlled study using tissue-mimicking phantoms. One challenge is to reproduce viscoelastic behavior in phantoms as observed in biological tissues. In this paper, polyacrylamide gel based tissue-mimicking phantoms have been developed to experimentally study the role of viscoelastic properties in a controlled manner. To measure the Young's modulus, the phantoms were subjected to linear loading, and the stressstrain relationship is deduced therefrom. It is seen that the phantoms show hysteresis behavior. The viscoelastic properties of these phantoms were measured by subjecting the samples to cyclic loading. Normal forces during this process of loading were also measured as a measure of sample elasticity. To emulate the normal and pathological lesions, samples were prepared with varying concentration of monomer and studied. Three models, namely, Maxwell, KelvinVoigt (KV), and KelvinVoigt fractional derivative (KVFD), were chosen to fit the experimental data. Of these, the KVFD model was found to be best fitting for the experimental data obtained. Results indicate that stiffer samples exhibit large variations in the storage modulus when the precompression levels are altered. © 2006 IEEE.

IEEE Transactions on Instrumentation and Measurement

Measurement of viscoelastic properties of polyacrylamide-based tissue-mimicking phantoms for ultrasound elastography applications

Owing to the physiological importance of the micellization process of bile salts, the critical micelle concentration (CMC) becomes a fundamental parameter in the evaluation of their biological activities. The present study suggests fluorescence probing, using 1,6-diphenylhexatriene (DPH), as a simple, convenient, sensitive and economic method for monitoring the micellization process of bile salts in aqueous medium. Three independent parameters: fluorescence intensity, anisotropy and lifetime of DPH have been employed successfully for determining the CMC of two bile salts, sodium deoxycholate (NaDC) and sodium cholate (NaC), in aqueous medium. The CMC values reported by all the above three parameters of DPH are found to be same and it is 16 mM for NaC and 6 mM for NaDC at 25 °C in unbuffered solution. The effect of temperature and ionic strength on the micellization process has also been investigated employing DPH as a fluorescent probe. Increasing temperature leads to the formation of fluffier micelles with less rigid interior for both NaC and NaDC. The micelle core of NaC is less perturbed by the presence of NaCl whereas in case of NaDC, the aggregates provide DPH a more nonpolar and rigid environment in presence of NaCl than that in absence of salt. © 2007 Elsevier B.V. All rights reserved.

Colloids and Surfaces B: Biointerfaces

Micellization of bile salts in aqueous medium: A fluorescence study

Leucinyl-phenylalanyl-valine (LFV) is a hydrophobic tripeptide with a flat egg shaped structure with the long axis dimension of about 12 angstroms. The effect of LFV on dimyristoylphosphatidylcholine (DMPC) liposome membrane has been studied by differential scanning calorimetry (DSC) and fluorescence spectroscopy. Calorimetric studies shows that incorporation of LFV completely abolishes the pretransition temperature with broadening of main transition temperature. Four conceptually different fluorescence probes, 1-naphthol (1-ROH) an excited state proton transfer probe, 8-anilino-1-naphthalenesulphonate (ANS) a solvent polarity probe, 1-6-diphenylhexatriene (DPH) an anisotropy probe and pyrene an excimer-forming probe have been used for fluorescence spectroscopic studies. For 1-ROH, ANS and DPH, a decreased partitioning with increasing mol.% of LFV was observed. Increasing LFV mol.% caused a decrease in the neutral form emission of 1-ROH, and a decrease in fluorescence intensity with red shift in ANS. The excimer formation ability of pyrene also decreased. The phase transition behavior of DMPC membrane in the presence of LFV was similar to the known effect of cholesterol on lipid bilayers. These results suggest that LFV cause an increased compactness of membrane.

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Effect of leucinyl-phenylalanyl-valine on DMPC liposome membrane

2010 7th International Conference on Electrical Engineering Computing Science and Automatic Control

Measurement of breast - tumor phantom dielectric properties for microwave breast cancer treatment evaluation

Colloid and Polymer Science

Micropolarity and microviscosity of Pluronics L62 and L64 core–shell aggregates in water at various concentrations and additives examined by absorption and fluorescence probes

Estimating viscosity and polarity in the microenvironment of polymeric gels - Introducing a microviscosity parameter

Journal	Journal of Polymer Research
ISSN	10229760
Open Access	No