Usharani Subuddhi - Academia.edu (original) (raw)
Papers by Usharani Subuddhi
Photochemical and Photobiological Sciences, Nov 1, 2007
Newkome-type first, second and third generation dendrimers, having t-butyl (GB), ethyl (GE) and c... more Newkome-type first, second and third generation dendrimers, having t-butyl (GB), ethyl (GE) and carboxylic (GA) end groups, were synthesized. A pyrene group, which can act as fluorescent sensor, was attached to the core of the dendrimers and their photophysical properties in aqueous solution were studied. These dendrimers were found to aggregate in aqueous solution, which manifested as an excimer peak in the pyrene emission spectra for the first and second generation dendrimers with ethyl and t-butyl end groups. The excimer peak however was not seen in case of the third generation dendrimer. Dendrimers with carboxylic end groups, did not show the excimer peak in water, which implies the hydrophobic nature of the aggregation. It is observed that the intensity of the excimer peak decreases with the increase in the size of the dendrimer. Lifetime studies carried out on the first and second generation dendrimers showed the formation of excimer species as a risetime in the decay curve. The aggregation of the third generation dendrimer was proposed from the quenching studies using silver ions and CCl 4 as quenchers.
Journal of Photochemistry and Photobiology A: Chemistry
Interpenetrating Polymer Network: Biomedical Applications
With advances in modern medicine, there has been a constant need to develop a single material tha... more With advances in modern medicine, there has been a constant need to develop a single material that caters to all demands such as high tensile strength, biocompatibility and biodegradability. The development of an interpenetrating polymer network (IPN) is both an outstanding innovation and contribution that has led to massive technological advances across a wide spectrum of applications in medicine. IPNs comprising natural and synthetic polymers are typically endowed with improved properties compared to monolithic materials and offer superior properties. Most importantly, synergism of properties has also been observed in most of the systems. This chapter discusses the potential of alginate-based IPN carriers for biomedical applications.
Optical Spectroscopic and Microscopic Techniques, 2022
Plant and Algal Hydrogels for Drug Delivery and Regenerative Medicine, 2021
As global population surges, the need for better health care inevitably intensifies. With increas... more As global population surges, the need for better health care inevitably intensifies. With increasing demand, the dependence on natural polysaccharides consequently spearheads. Guar gum (GG), a seed gum, is the one to definitely watch out for. GG has demonstrated immense potential in all major fields of biomedicine. From drug delivery to tissue engineering, GG has been omnipresent. Endowed with many magnificent attributes such as easy accessibility, high compatibility with living tissues, and susceptibility to microbial degradation, GG has been one of the most preferred choices in biomedical research. Many reports on GG and with many more in the pipeline have been dedicated to cater to the never-ending demand of smart biomaterials. GG, in drug delivery, has not only been a boon but also a pharmaceutical wonder. This chapter provides a state-of-the-art summary of GG in the delivery of an array of medications.
Journal of Photochemistry and Photobiology A: Chemistry, 2021
Abstract The ever growing importance of colloids based on steroidal surfactants in diverse fields... more Abstract The ever growing importance of colloids based on steroidal surfactants in diverse fields demands a comprehensive understanding of the self-assembly behaviour of these unconventional amphiphiles, which is less explored and poorly understood. Hence, a detailed investigation and a comparative analysis on the aggregation process of CHAPS (3-[(3-cholamidopropyl)-dimethylamino]-1-propanesulfonate), the zwitterionic derivative of cholic acid, and its bile salt analogues (cholates) is considered necessary for fundamental understanding and applications. In the present study, modulation in the photophysics of a small fluorescent molecule, Coumarin 1 has been utilised to get insight into the aggregation pattern and the micellar properties of CHAPS. Though CHAPS shares maximum homology with the cholates, yet its aggregation behaviour is more inclined towards that of the deoxycholates. It follows Small's model exhibiting some degree of criticalness, unlike the cholates, thus signifying the importance of the zwitterionic tail in the formation and stabilisation of the CHAPS micelles. The effect of salt concentration and temperature on the self-assembly process and micellar properties of CHAPS has been investigated. The effect of Sodium cholate and Sodium taurocholate as co-surfactants has also been monitored to understand the formation of mixed micelles. The various photophysical parameters reveal that CHAPS micelles offer a relatively more hydrophobic, compact and non-polar microenvironment to Coumarin 1 than the bile salts, indicating efficient packing of CHAPS molecules in the micelles. Owing to the superior nature of CHAPS aggregates and better shielding of guest molecules in the micelles, CHAPS based colloids could be promising candidates as potential delivery systems for biomedical applications.
ChemistrySelect, 2020
The current work describes the selective colorimetric detection of metal ions using a simple azo ... more The current work describes the selective colorimetric detection of metal ions using a simple azo dye (L1) containing donor‐π‐acceptor framework. In this chromogenic probe, salicylaldehyde is used as donor and nitrobenzene group as acceptor unit. L1 is found to show selective recognition of mercuric ion both visually and spectrophotometrically with no interference from environmentally relevant metal ions in DMSO‐water mixture. It exhibits reddish‐pink colour in DMSO‐water medium as a result of intramolecular charge transfer (ICT) from the electron donating phenolic group to electron withdrawing nitrobenzene group. It selectively binds with Hg2+ even in presence of other interfering metal ions and form a 1 : 1 L1‐Hg2+ adduct. It is evident from a change in colour along with a decrease of ICT absorption band and hypsochromic shift of π‐π* band. The binding of the chemosensor and mercuric ion through the salicylaldehyde unit is proved from 1H‐NMR data and DFT calculations. Using UV‐Vis ...
Journal of Molecular Liquids, 2020
Abstract Chrysin (5, 7-dihydroxyflavone) (CHR), a wonder flavonoid that nature has bestowed upon ... more Abstract Chrysin (5, 7-dihydroxyflavone) (CHR), a wonder flavonoid that nature has bestowed upon us, is endowed with a broad spectrum of pharmacological properties. Nonetheless, the practical uses of CHR are greatly impeded owing to its poor aqueous solubility and low oral bioavailability. Inclusion complexes (ICs) in β-cyclodextrin (β-CD) have been an effectual strategy for the same and herein, CHR/β-CD solid ICs were accomplished by diverse approaches. The inclusion phenomenon was affirmed from different spectroscopic techniques. Molecular dynamic simulation studies ascertained the high stability of CHR/β-CD IC. The microwave irradiation method, which is environmentally more benign, was found to be the optimum wherein the product (MW) exhibited better characteristics in terms of drug content and dissolution. In vitro hemolytic assay revealed no adverse effect on RBC morphology and the toxicity of CHR was significantly reduced by employing MW. Furthermore, the MW product demonstrated improved chemosensitivity potency in terms of intracellular uptake and cytotoxicity against MCF-7cells in comparison to pristine CHR. Our findings unambiguously validate the efficacy of MW as a superior drug formulation for pharmaceutical applications of CHR delivery.
Langmuir, 2019
The photophysical behavior of Coumarin1 (Cou1), a well known 7-aminocoumarin derivative, is very ... more The photophysical behavior of Coumarin1 (Cou1), a well known 7-aminocoumarin derivative, is very sensitive to the microenvironment in which it resides. In the present study, the effect of six bile salt variants on the photophysical behavior of Cou1 has been investigated. Dihydroxy (deoxycholates) as well as trihydroxy (cholates) bile salts with conjugated and unconjugated side chains have been chosen to get insight into the role of bile salt structure on the microenvironment of Cou1. Cou1 photophysics was found to be extremely sensitive to the aggregation process of the bile salt variants. The reduced polarity of the micellar environment stabilizes the planar intramolecular charge transferred state of Cou1 resulting in significant modulation in its photophysics in the bile salt media. The changes in the fluorescence parameters such as fluorescence intensity, emission energy, fluorescence quantum yield, anisotropy and lifetime of Cou1 reveal that there is a distinct difference in the aggregation behavior of deoxycholates from that of cholates. The deoxycholates form micelles more or less critically similar to that of conventional surfactants, whereas the cholates self-assemble rather non-critically over a wide concentration range, thus signifying the vital role of the extra hydroxyl group in the aggregation pattern of trihydroxy bile salts. The conjugated bile salts are found to provide a relatively more compact, rigid and hydrophobic microenvironment to Cou1 as compared to their unconjugated counterparts. Considering the significant modulation in the photophysical properties of Cou1, it has been employed as a molecular reporter for monitoring the aggregation process of bile salt variants and important information could be obtained about the effect of bile salt structure on the aggregation pattern and also about the micellar properties.
Dyes and Pigments, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Polymer Bulletin, 2018
Smart hydrogels comprising guar gum (GG) and poly(N-isopropylacrylamide) (PNI-PAAm) cross-linked ... more Smart hydrogels comprising guar gum (GG) and poly(N-isopropylacrylamide) (PNI-PAAm) cross-linked using a non-toxic cross-linker, tetraethyl orthosilicate, have been designed to explore the sustained release of an anticancer drug, 5-fluorouracil (5FU). Hydrogels containing preformed solid inclusion complexes (IC) of 5FU in β-cyclodextrin (β-CD) were designed to regulate the drug delivery. The formation of true 5FU/β-CD ICs was affirmed from different spectroscopic techniques. The DSC studies of the hydrogels revealed that the thermosensitivity of PNIPAAm is retained in the resultant hydrogels, also corroborated from the swelling measurements. The rate of 5FU release from the hydrogels containing the IC was significantly prolonged in comparison with those containing the free drug. Higher amounts of GG in the matrix led to slower release of drug. The preliminary kinetics of drug release indicated the collective influence of β-CD and GG content on the polymer relaxation process which was key in sustaining the drug delivery. Release studies in simulated gastric (SGF) and intestinal (SIF) fluids showed less than 10% of 5FU release during the initial 2 h in SGF and an increased release in SIF. Thus, the developed smart hydrogels can be utilized as potential candidates for sustained oral delivery of 5FU to the intestine.
Journal of Pharmaceutical Analysis, 2018
Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized ... more Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized using glutaraldehyde as crosslinker and investigated for controlled delivery of the common anti-inflammatory drug, ibuprofen (IBF). To regulate the drug delivery, solid inclusion complexes (ICs) of IBF in β-cyclodextrin (β-CD) were prepared and added to the hydrogels. The ICs were prepared by the microwave irradiation method, which is more environmentally benign. The formation of IC was confirmed by various analytical techniques and the synthesized hydrogels were also characterized. Controlled release of drug was achieved from the hydrogels containing the ICs in comparison to the rapid release from hydrogels containing free IBF. The preliminary kinetic analysis emphasized the crucial role of β-CD in the drug release process that influences the polymer relaxation, thereby leading to prolonged release. The cytotoxicity assay validated the hydrogels as non-toxic in nature and hence can be utilized for controlled delivery of IBF.
Polymer Science Series A, 2016
pH-Responsive hydrogels comprised of chitosan and poly(vinyl alcohol) were explored for the contr... more pH-Responsive hydrogels comprised of chitosan and poly(vinyl alcohol) were explored for the controlled delivery of diclofenac sodium (DS) to the intestine. To regulate the drug delivery, preformed solid inclusion complex of DS with β-cyclodextrin (β-CD) was added into the hydrogels. Negligible drug release was observed in the simulated gastric fluid and sustained release in the intestinal fluid. The preliminary kinetics revealed that the drug release follows anomalous transport mechanism which is influenced by the presence of β-CD. The pH-specific release behavior of these hydrogels suggests them to be ideal candidates for oral controlled delivery of DS to the intestine.
Journal of Molecular Structure, 2015
Abstract Inclusion complexes of diclofenac sodium (DS) with β–cyclodextrin (β–CD) were prepared i... more Abstract Inclusion complexes of diclofenac sodium (DS) with β–cyclodextrin (β–CD) were prepared in order to improve the solubility, dissolution and oral bioavailability of the poorly water soluble drug. The effect of method of preparation of the DS/β−CD inclusion complexes (ICs) was investigated. The ICs were prepared by microwave irradiation and also by the conventional methods of kneading, co-precipitation and freeze drying. Though freeze drying method is usually referred to as the gold standard among all the conventional methods, its long processing time limits the utility. Microwave irradiation accomplishes the process in a very short span of time and is a more environmentally benign method. Better efficacy of the microwaved inclusion product (MW) was observed in terms of dissolution, antimicrobial activity and antibiofilm properties of the drug. Thus microwave irradiation can be utilized as an improved, time-saving and cost-effective method for the generation of DS/β–CD inclusion complexes.
International Journal of Biological Macromolecules, 2015
pH-Responsive hydrogel systems based on guar gum (GG), poly(acrylic acid) (PAA) and -cyclodextri... more pH-Responsive hydrogel systems based on guar gum (GG), poly(acrylic acid) (PAA) and -cyclodextrin (CD) using a non-toxic crosslinker, tetraethyl orthosilicate for intestinal delivery of dexamethasone (DX) has been reported. Hydrogels of different compositions were synthesized and evaluated for the controlled delivery of DX. The hydrogels exhibited pH-responsive swelling behavior with a maximum swelling around neutral pH. The CD-containing hydrogels deliver the drug at much slower rate in contrast to the ones without CD. Moreover, the drug release rate is found to show a strong dependence on the GG content and the effect of GG is more pronounced in case of the CD containing hydrogels. As the GG content increases, the rate of drug release decreases considerably and the drug release is prolonged. The release studies in the simulated conditions reveal that these hydrogels can be used as delivery vehicles for oral administration of DX targeting the intestine. Cell viability studies reveal the hydrogels to be biocompatible in nature thus validating them as good drug delivery systems.
RSC Advances, 2014
ABSTRACT
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Interesting solvatochromism in polyether dendron aggregates in mixed aqueous media. Reversal in s... more Interesting solvatochromism in polyether dendron aggregates in mixed aqueous media. Reversal in solvatochromic behaviour depending on percentage of nonaqueous solvent. Negative-solvatochromism due to progressive disaggregation of dendron aggregates. Positive-solvatochromism is shown by the dendron monomers. Higher dendron hydrophobicity requires more of second solvent for disaggregation. g r a p h i c a l a b s t r a c t Reversal in solvatochromic behaviour of dendrons in aqueous medium on addition of a nonaqueous solvent. Negative-solvatochromism is attributed to the progressive disaggregation of dendron aggregates and the positive-solvatochromism is exhibited by the dendron monomers.
Photochemical & Photobiological Sciences, 2009
A detailed account of the photophysical behaviour of the phototautomer (PT) and the ground state ... more A detailed account of the photophysical behaviour of the phototautomer (PT) and the ground state anion (A-) of 3-hydroxyflavone in liposome membrane at various membrane conditions is presented. A quenching study with a hydrophilic quencher Ag + suggests that the phototautomeric emission generates from the fraction of 3HF that is located at the inner hydrophobic core, whereas the ground state anionic emission is from the fraction that resides near the water-accessible surface site. However, the biexponential nature of fluorescence decays of both the forms indicates that there is local heterogeneity in the distribution. Temperature dependence studies and experiments in the presence of ethanol reveal that, as the membrane becomes more fluid, redistribution of 3HF takes place between the two sites leading to increase in Apopulation. The temperature dependence of the fluorescence anisotropy change of PT shows good correlation with the phase change and shows a sharp drop at the transition temperature, whereas the corresponding change in the case of Ais gradual.
Photochemical & Photobiological Sciences, 2006
The photophysical behaviour of a new pyrene derivative, 1-(4-N,N-dimethylaminophenylethynyl)pyren... more The photophysical behaviour of a new pyrene derivative, 1-(4-N,N-dimethylaminophenylethynyl)pyrene (DMAPEPy), in various solvents has been studied. Due to the presence of an ethynyl link with a cylindrical p cloud between the donor (N,N-dimethyl group) and the acceptor (pyrene), the molecule shows efficient intramolecular charge transfer, with a high extinction coefficient in all the solvents. There is significant solvatochromism in the fluorescence with a large increase in the Stokes' shift of around 125 nm between n-hexane and acetonitrile. The solvent-dependent spectral data show a good correlation with the Kamlet-Taft solvent polarity parameter (p*). The plots of Stokes' shifts with E T (30) are linear for non-protic solvents and for protic solvents but with different slopes. The fluorescence quantum yields are high for non-polar solvents and decrease as the solvent polarity increases. Unlike the parent molecule pyrene, DMAPEPy shows a short lifetime, which is fairly insensitive to oxygen-induced quenching and is dependent on solvent polarity. The molecule shows high steady-state fluorescence anisotropy, which is very sensitive to the viscosity change of the medium.
Photochemical and Photobiological Sciences, Nov 1, 2007
Newkome-type first, second and third generation dendrimers, having t-butyl (GB), ethyl (GE) and c... more Newkome-type first, second and third generation dendrimers, having t-butyl (GB), ethyl (GE) and carboxylic (GA) end groups, were synthesized. A pyrene group, which can act as fluorescent sensor, was attached to the core of the dendrimers and their photophysical properties in aqueous solution were studied. These dendrimers were found to aggregate in aqueous solution, which manifested as an excimer peak in the pyrene emission spectra for the first and second generation dendrimers with ethyl and t-butyl end groups. The excimer peak however was not seen in case of the third generation dendrimer. Dendrimers with carboxylic end groups, did not show the excimer peak in water, which implies the hydrophobic nature of the aggregation. It is observed that the intensity of the excimer peak decreases with the increase in the size of the dendrimer. Lifetime studies carried out on the first and second generation dendrimers showed the formation of excimer species as a risetime in the decay curve. The aggregation of the third generation dendrimer was proposed from the quenching studies using silver ions and CCl 4 as quenchers.
Journal of Photochemistry and Photobiology A: Chemistry
Interpenetrating Polymer Network: Biomedical Applications
With advances in modern medicine, there has been a constant need to develop a single material tha... more With advances in modern medicine, there has been a constant need to develop a single material that caters to all demands such as high tensile strength, biocompatibility and biodegradability. The development of an interpenetrating polymer network (IPN) is both an outstanding innovation and contribution that has led to massive technological advances across a wide spectrum of applications in medicine. IPNs comprising natural and synthetic polymers are typically endowed with improved properties compared to monolithic materials and offer superior properties. Most importantly, synergism of properties has also been observed in most of the systems. This chapter discusses the potential of alginate-based IPN carriers for biomedical applications.
Optical Spectroscopic and Microscopic Techniques, 2022
Plant and Algal Hydrogels for Drug Delivery and Regenerative Medicine, 2021
As global population surges, the need for better health care inevitably intensifies. With increas... more As global population surges, the need for better health care inevitably intensifies. With increasing demand, the dependence on natural polysaccharides consequently spearheads. Guar gum (GG), a seed gum, is the one to definitely watch out for. GG has demonstrated immense potential in all major fields of biomedicine. From drug delivery to tissue engineering, GG has been omnipresent. Endowed with many magnificent attributes such as easy accessibility, high compatibility with living tissues, and susceptibility to microbial degradation, GG has been one of the most preferred choices in biomedical research. Many reports on GG and with many more in the pipeline have been dedicated to cater to the never-ending demand of smart biomaterials. GG, in drug delivery, has not only been a boon but also a pharmaceutical wonder. This chapter provides a state-of-the-art summary of GG in the delivery of an array of medications.
Journal of Photochemistry and Photobiology A: Chemistry, 2021
Abstract The ever growing importance of colloids based on steroidal surfactants in diverse fields... more Abstract The ever growing importance of colloids based on steroidal surfactants in diverse fields demands a comprehensive understanding of the self-assembly behaviour of these unconventional amphiphiles, which is less explored and poorly understood. Hence, a detailed investigation and a comparative analysis on the aggregation process of CHAPS (3-[(3-cholamidopropyl)-dimethylamino]-1-propanesulfonate), the zwitterionic derivative of cholic acid, and its bile salt analogues (cholates) is considered necessary for fundamental understanding and applications. In the present study, modulation in the photophysics of a small fluorescent molecule, Coumarin 1 has been utilised to get insight into the aggregation pattern and the micellar properties of CHAPS. Though CHAPS shares maximum homology with the cholates, yet its aggregation behaviour is more inclined towards that of the deoxycholates. It follows Small's model exhibiting some degree of criticalness, unlike the cholates, thus signifying the importance of the zwitterionic tail in the formation and stabilisation of the CHAPS micelles. The effect of salt concentration and temperature on the self-assembly process and micellar properties of CHAPS has been investigated. The effect of Sodium cholate and Sodium taurocholate as co-surfactants has also been monitored to understand the formation of mixed micelles. The various photophysical parameters reveal that CHAPS micelles offer a relatively more hydrophobic, compact and non-polar microenvironment to Coumarin 1 than the bile salts, indicating efficient packing of CHAPS molecules in the micelles. Owing to the superior nature of CHAPS aggregates and better shielding of guest molecules in the micelles, CHAPS based colloids could be promising candidates as potential delivery systems for biomedical applications.
ChemistrySelect, 2020
The current work describes the selective colorimetric detection of metal ions using a simple azo ... more The current work describes the selective colorimetric detection of metal ions using a simple azo dye (L1) containing donor‐π‐acceptor framework. In this chromogenic probe, salicylaldehyde is used as donor and nitrobenzene group as acceptor unit. L1 is found to show selective recognition of mercuric ion both visually and spectrophotometrically with no interference from environmentally relevant metal ions in DMSO‐water mixture. It exhibits reddish‐pink colour in DMSO‐water medium as a result of intramolecular charge transfer (ICT) from the electron donating phenolic group to electron withdrawing nitrobenzene group. It selectively binds with Hg2+ even in presence of other interfering metal ions and form a 1 : 1 L1‐Hg2+ adduct. It is evident from a change in colour along with a decrease of ICT absorption band and hypsochromic shift of π‐π* band. The binding of the chemosensor and mercuric ion through the salicylaldehyde unit is proved from 1H‐NMR data and DFT calculations. Using UV‐Vis ...
Journal of Molecular Liquids, 2020
Abstract Chrysin (5, 7-dihydroxyflavone) (CHR), a wonder flavonoid that nature has bestowed upon ... more Abstract Chrysin (5, 7-dihydroxyflavone) (CHR), a wonder flavonoid that nature has bestowed upon us, is endowed with a broad spectrum of pharmacological properties. Nonetheless, the practical uses of CHR are greatly impeded owing to its poor aqueous solubility and low oral bioavailability. Inclusion complexes (ICs) in β-cyclodextrin (β-CD) have been an effectual strategy for the same and herein, CHR/β-CD solid ICs were accomplished by diverse approaches. The inclusion phenomenon was affirmed from different spectroscopic techniques. Molecular dynamic simulation studies ascertained the high stability of CHR/β-CD IC. The microwave irradiation method, which is environmentally more benign, was found to be the optimum wherein the product (MW) exhibited better characteristics in terms of drug content and dissolution. In vitro hemolytic assay revealed no adverse effect on RBC morphology and the toxicity of CHR was significantly reduced by employing MW. Furthermore, the MW product demonstrated improved chemosensitivity potency in terms of intracellular uptake and cytotoxicity against MCF-7cells in comparison to pristine CHR. Our findings unambiguously validate the efficacy of MW as a superior drug formulation for pharmaceutical applications of CHR delivery.
Langmuir, 2019
The photophysical behavior of Coumarin1 (Cou1), a well known 7-aminocoumarin derivative, is very ... more The photophysical behavior of Coumarin1 (Cou1), a well known 7-aminocoumarin derivative, is very sensitive to the microenvironment in which it resides. In the present study, the effect of six bile salt variants on the photophysical behavior of Cou1 has been investigated. Dihydroxy (deoxycholates) as well as trihydroxy (cholates) bile salts with conjugated and unconjugated side chains have been chosen to get insight into the role of bile salt structure on the microenvironment of Cou1. Cou1 photophysics was found to be extremely sensitive to the aggregation process of the bile salt variants. The reduced polarity of the micellar environment stabilizes the planar intramolecular charge transferred state of Cou1 resulting in significant modulation in its photophysics in the bile salt media. The changes in the fluorescence parameters such as fluorescence intensity, emission energy, fluorescence quantum yield, anisotropy and lifetime of Cou1 reveal that there is a distinct difference in the aggregation behavior of deoxycholates from that of cholates. The deoxycholates form micelles more or less critically similar to that of conventional surfactants, whereas the cholates self-assemble rather non-critically over a wide concentration range, thus signifying the vital role of the extra hydroxyl group in the aggregation pattern of trihydroxy bile salts. The conjugated bile salts are found to provide a relatively more compact, rigid and hydrophobic microenvironment to Cou1 as compared to their unconjugated counterparts. Considering the significant modulation in the photophysical properties of Cou1, it has been employed as a molecular reporter for monitoring the aggregation process of bile salt variants and important information could be obtained about the effect of bile salt structure on the aggregation pattern and also about the micellar properties.
Dyes and Pigments, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Polymer Bulletin, 2018
Smart hydrogels comprising guar gum (GG) and poly(N-isopropylacrylamide) (PNI-PAAm) cross-linked ... more Smart hydrogels comprising guar gum (GG) and poly(N-isopropylacrylamide) (PNI-PAAm) cross-linked using a non-toxic cross-linker, tetraethyl orthosilicate, have been designed to explore the sustained release of an anticancer drug, 5-fluorouracil (5FU). Hydrogels containing preformed solid inclusion complexes (IC) of 5FU in β-cyclodextrin (β-CD) were designed to regulate the drug delivery. The formation of true 5FU/β-CD ICs was affirmed from different spectroscopic techniques. The DSC studies of the hydrogels revealed that the thermosensitivity of PNIPAAm is retained in the resultant hydrogels, also corroborated from the swelling measurements. The rate of 5FU release from the hydrogels containing the IC was significantly prolonged in comparison with those containing the free drug. Higher amounts of GG in the matrix led to slower release of drug. The preliminary kinetics of drug release indicated the collective influence of β-CD and GG content on the polymer relaxation process which was key in sustaining the drug delivery. Release studies in simulated gastric (SGF) and intestinal (SIF) fluids showed less than 10% of 5FU release during the initial 2 h in SGF and an increased release in SIF. Thus, the developed smart hydrogels can be utilized as potential candidates for sustained oral delivery of 5FU to the intestine.
Journal of Pharmaceutical Analysis, 2018
Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized ... more Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized using glutaraldehyde as crosslinker and investigated for controlled delivery of the common anti-inflammatory drug, ibuprofen (IBF). To regulate the drug delivery, solid inclusion complexes (ICs) of IBF in β-cyclodextrin (β-CD) were prepared and added to the hydrogels. The ICs were prepared by the microwave irradiation method, which is more environmentally benign. The formation of IC was confirmed by various analytical techniques and the synthesized hydrogels were also characterized. Controlled release of drug was achieved from the hydrogels containing the ICs in comparison to the rapid release from hydrogels containing free IBF. The preliminary kinetic analysis emphasized the crucial role of β-CD in the drug release process that influences the polymer relaxation, thereby leading to prolonged release. The cytotoxicity assay validated the hydrogels as non-toxic in nature and hence can be utilized for controlled delivery of IBF.
Polymer Science Series A, 2016
pH-Responsive hydrogels comprised of chitosan and poly(vinyl alcohol) were explored for the contr... more pH-Responsive hydrogels comprised of chitosan and poly(vinyl alcohol) were explored for the controlled delivery of diclofenac sodium (DS) to the intestine. To regulate the drug delivery, preformed solid inclusion complex of DS with β-cyclodextrin (β-CD) was added into the hydrogels. Negligible drug release was observed in the simulated gastric fluid and sustained release in the intestinal fluid. The preliminary kinetics revealed that the drug release follows anomalous transport mechanism which is influenced by the presence of β-CD. The pH-specific release behavior of these hydrogels suggests them to be ideal candidates for oral controlled delivery of DS to the intestine.
Journal of Molecular Structure, 2015
Abstract Inclusion complexes of diclofenac sodium (DS) with β–cyclodextrin (β–CD) were prepared i... more Abstract Inclusion complexes of diclofenac sodium (DS) with β–cyclodextrin (β–CD) were prepared in order to improve the solubility, dissolution and oral bioavailability of the poorly water soluble drug. The effect of method of preparation of the DS/β−CD inclusion complexes (ICs) was investigated. The ICs were prepared by microwave irradiation and also by the conventional methods of kneading, co-precipitation and freeze drying. Though freeze drying method is usually referred to as the gold standard among all the conventional methods, its long processing time limits the utility. Microwave irradiation accomplishes the process in a very short span of time and is a more environmentally benign method. Better efficacy of the microwaved inclusion product (MW) was observed in terms of dissolution, antimicrobial activity and antibiofilm properties of the drug. Thus microwave irradiation can be utilized as an improved, time-saving and cost-effective method for the generation of DS/β–CD inclusion complexes.
International Journal of Biological Macromolecules, 2015
pH-Responsive hydrogel systems based on guar gum (GG), poly(acrylic acid) (PAA) and -cyclodextri... more pH-Responsive hydrogel systems based on guar gum (GG), poly(acrylic acid) (PAA) and -cyclodextrin (CD) using a non-toxic crosslinker, tetraethyl orthosilicate for intestinal delivery of dexamethasone (DX) has been reported. Hydrogels of different compositions were synthesized and evaluated for the controlled delivery of DX. The hydrogels exhibited pH-responsive swelling behavior with a maximum swelling around neutral pH. The CD-containing hydrogels deliver the drug at much slower rate in contrast to the ones without CD. Moreover, the drug release rate is found to show a strong dependence on the GG content and the effect of GG is more pronounced in case of the CD containing hydrogels. As the GG content increases, the rate of drug release decreases considerably and the drug release is prolonged. The release studies in the simulated conditions reveal that these hydrogels can be used as delivery vehicles for oral administration of DX targeting the intestine. Cell viability studies reveal the hydrogels to be biocompatible in nature thus validating them as good drug delivery systems.
RSC Advances, 2014
ABSTRACT
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Interesting solvatochromism in polyether dendron aggregates in mixed aqueous media. Reversal in s... more Interesting solvatochromism in polyether dendron aggregates in mixed aqueous media. Reversal in solvatochromic behaviour depending on percentage of nonaqueous solvent. Negative-solvatochromism due to progressive disaggregation of dendron aggregates. Positive-solvatochromism is shown by the dendron monomers. Higher dendron hydrophobicity requires more of second solvent for disaggregation. g r a p h i c a l a b s t r a c t Reversal in solvatochromic behaviour of dendrons in aqueous medium on addition of a nonaqueous solvent. Negative-solvatochromism is attributed to the progressive disaggregation of dendron aggregates and the positive-solvatochromism is exhibited by the dendron monomers.
Photochemical & Photobiological Sciences, 2009
A detailed account of the photophysical behaviour of the phototautomer (PT) and the ground state ... more A detailed account of the photophysical behaviour of the phototautomer (PT) and the ground state anion (A-) of 3-hydroxyflavone in liposome membrane at various membrane conditions is presented. A quenching study with a hydrophilic quencher Ag + suggests that the phototautomeric emission generates from the fraction of 3HF that is located at the inner hydrophobic core, whereas the ground state anionic emission is from the fraction that resides near the water-accessible surface site. However, the biexponential nature of fluorescence decays of both the forms indicates that there is local heterogeneity in the distribution. Temperature dependence studies and experiments in the presence of ethanol reveal that, as the membrane becomes more fluid, redistribution of 3HF takes place between the two sites leading to increase in Apopulation. The temperature dependence of the fluorescence anisotropy change of PT shows good correlation with the phase change and shows a sharp drop at the transition temperature, whereas the corresponding change in the case of Ais gradual.
Photochemical & Photobiological Sciences, 2006
The photophysical behaviour of a new pyrene derivative, 1-(4-N,N-dimethylaminophenylethynyl)pyren... more The photophysical behaviour of a new pyrene derivative, 1-(4-N,N-dimethylaminophenylethynyl)pyrene (DMAPEPy), in various solvents has been studied. Due to the presence of an ethynyl link with a cylindrical p cloud between the donor (N,N-dimethyl group) and the acceptor (pyrene), the molecule shows efficient intramolecular charge transfer, with a high extinction coefficient in all the solvents. There is significant solvatochromism in the fluorescence with a large increase in the Stokes' shift of around 125 nm between n-hexane and acetonitrile. The solvent-dependent spectral data show a good correlation with the Kamlet-Taft solvent polarity parameter (p*). The plots of Stokes' shifts with E T (30) are linear for non-protic solvents and for protic solvents but with different slopes. The fluorescence quantum yields are high for non-polar solvents and decrease as the solvent polarity increases. Unlike the parent molecule pyrene, DMAPEPy shows a short lifetime, which is fairly insensitive to oxygen-induced quenching and is dependent on solvent polarity. The molecule shows high steady-state fluorescence anisotropy, which is very sensitive to the viscosity change of the medium.