Silver nanoparticles (Ag NPs) are now widely used as antibacterial and antifungal materials in different consumer products. We report here the preparation of Ag NPs by neem leaves extract (Azadirachta) reduction and trisodium citrate-sodium borohydride reduction methods, and study of their phytotoxicity. The nanoparticles were characterized by UV-Vis spectroscopy, FTIR, and atomic force microscopy (AFM) techniques. Both neem-coated and citrate-coated Ag NPs exhibit surface plasmon around 400 nm, and their average sizes measured by AFM are about 100 and 20 nm, respectively. Antibacterial and antifungal activities of these nanomaterials have been studied by simple pea seed germination and disk diffusion methods. It has been observed from the growth of root and shoot, citrate-coated Ag NPs significantly affect seedling growth, but neem-coated Ag NPs exhibit somehow mild toxicity toward germination process due to the nutrient supplements from neem. On the other hand, antifungal activity of neem-coated Ag NPs has been found much higher than that of citrate-coated Ag NPs due to the combined effects of antifungal activity of neem and Ag NPs. Present research primarily indicates a possible application of neem-coated Ag NPs as a potential fungicide.

Chitosan is a biodegradable polymer obtained easily from natural polymer chitin which is abundantly found in the outer hard skeleton of shellfishes like crab, lobster, and shrimp. It has immense pharmaceutical uses as anti-oxidant and anti-bacterial material. We have presented here one-step hydrothermal method of preparation of depolymerized water dispersible chitosan particles using citric acid as a depolymerizer and ionic cross linker and their stabilizing effect on cow milk proteins from fluorimetric and differential scanning calorimetric studies. We report for the first time protein stabilizing effect of depolymerized chitosan from thermal denaturation of milk protein. This has been explained by carbohydrate like structural skeleton of chitosan.