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...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.展开更多
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 a...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.展开更多
文摘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.
文摘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.
