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Fabrication of core-shell PLGA/PLA-pNIPAM nanocomposites for improved entrapment and release kinetics of antihypertensive drugs

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Particuology 2018年第5期16卷 169-176页

作者： Tanushree Basu bonamali pal Satnam Singh School of Chemistry and Biochemistry Thapar lnstitute of Engineering and TechnologyPatiala 147004Punjablndia

Polylactic acid (PLA)and poly(lactic-co-glycolic)acid (PLGA)are two commonly applied biodegrad- able polymers for the preparation of nanocomposites used in drug-delivery systems.However,these polymers lack desirable attributes such as resistance to aggregation during long-term storage due to lyophilisation.To improve their efficacy,in this work,PLA and PLGA were encapsulated within a shell of poly(N-isopropylacrylamide)(pNIPAM)using a single emulsion technique followed by an aqueous free radical precipitation polymerisation process,yielding core-shell PLA/PLGA-pNIPAM nanocomposites. The nanocomposites were cbaracterised using zeta potential,dynamic light scattering,and transmission electron microscopy analyses and were further applied as a delivery system for ramipril,an antihypertensive drug.The drug-loaded PLGA-pNIPAM core-shell nanoparticles exhibited a higher drug content (91%)and entrapment efficiency (78%)than their PLA counterparts.An in vitro release study of the formulations at pH 7.3in phosphate-buffered saline indicated that PLGA was more efficient than PLA with a sustained release of 86% of ramipril from the polymer matrix within 24h.Furthermore,to determine the release kinetics,the data were fitted to Korsmeyer-Peppas and Higuchi models;the release of ramipril from the polymer matrix followed zero-order rate kinetics and an anomalous (non-Fickian)diffusion mechanism.

关键词： Poly(lactic-co-glycolic)acid Polylactic acid Poly(N-isopropylacrylamide) Antihypertensive drug Entrapment efficiency Drug release

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SiO2-coated pure anatase TiO2 catalysts for enhanced photo-oxidation of naphthalene and anthracene

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Particuology 2017年第5期15卷 156-161页

作者： Inderpreet Singh Grover Roop Chand Prajapat Satnam Singh bonamali pal Department of Chemistry Public College Samana 147101 Punjab India School of Chemistry and Biochemistry Thapar University Putiala 147004 Punjab India

Our current efforts reveal the preparation of SiO2@TiO2 nanocomposites having different thicknesses of silica shell and the relationship to photocatalytic activity （PCA） for the photo-oxidation of naph-thalene and anthracene. The presence of SiO2 coating over TiO2 surface was demonstrated by FT-IR analysis, with peaks corresponding to Si-O-Si （1081 cm 1） and Si-O-Ti （950 cm-1） bonds observed. High-resolution transmission electron microscopy analysis confirmed the presence of SiO2 in the as- prepared nanocomposites and the amount of Si, Ti, and O was determined by energy dispersive X-ray spectroscopy analysis. Increasing the Si02 shell thickness increases the surface area of the nanocompos- ites （69-235 m2/g）, which enhances naphthalene/anthracene adsorption. However, the observed PCA trend presents an inverse correlation to the adsorption studies, where the as-prepared samples possess- ing the highest surface areas exhibited the least PCA, while catalysts having lower surface areas （among silica coated samples） displayed the highest PCA in the degradation of naphthalene and anthracene to CO2. Despite complete degradation of naphthalene and anthracene, incomplete mineralization occurred, ascribed to the formation of various intermediates, identified by GC-MS analysis.

关键词： Silica coating Naphthalene Anthracene Photo-oxidation TiO2 nanoparticles

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Impact of reducing and capping agents on carbohydrates for the growth of Ag and Cu nanostructures and their antibacterial activities

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Particuology 2019年第2期17卷 219-226页

作者： Rayees Ahmad Rather Ramandeep K. Sarwara Niranjan Das bonamali pal School of Chemistry and Biochemistry Thapar Institute of Engineering and Technology Patiala 147004 Punjab India Department of Biotechnology Thapar Institute of Engineering and Technology Patiala 147004 Punjab India

This study presents a viable green synthesis approach to produce Ag and Cu nanoparticles (MNPs) by using carbohydrates such as glucose, fructose, sucrose, and starch as reducing agents and describes theirantimicrobial activities against Escherichia coli DH5a. Optical and diffused light scattering analyses showed the Ag NPs ranged from 20 to 75 nm and the Cu NPs varied from 20 to 160 nm, which supports the differences in their absorption bands (400-434 nm for Ag and 458-641 nm for Cu). The reducing sugars interacted differently with Ag^+ and Cu^2+ based on their size and hydrolysis by NaOH resulting in effective stabilization of Ag^0 and Cu^0 and variation in the bactericidal activities of the MNPs. The antibacterial effects of the MNPs were evaluated by measuring the inhibition zones using E. coli DH5a as a test organism. No growth was observed by restreaking different parts of the clearly inhibited zones into new culture plates indicating the bactericidal efficacy of the Ag and Cu MNPs. The Ag NPs were found to be more effective in terms of the size of their in hibition zones (1.21-1.82 cm) compared with those of the Cu NPs (0.0-1.2 cm). This study provides a promising basis for the formulation of a new gen eration of bactericidal agents.

关键词： Green synthesis Ag and Cu nanoparticles Carbohydrate reducing agents Antibacterial activities

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