T.J. Cho, J. Liu, V.A. Hackley
National Institute of Standards and Technology,
Keywords: silver nanoparticles, positively charged, dendron, stability
Summary:We developed positively charged silver nanoparticles ([Ag-Ds]+), nominally 20 nm in diameter, using dendron chemistry combined with reduction of silver nitrate in the presence of sodium borohydride. The conjugate was developed within the context of potential biomedical applications. Rational design was applied to yield a dendron capping agent that enhances surface anchoring, hydrophilicity, and cationic surface charge. The colloidal stability and physico-chemical properties of the conjugate was evaluated under physiologically relevant conditions using dynamic light scattering, zeta potential, UV-vis absorbance, and transmission electron microscopy. Properties evaluated include size, size distribution, shape and uniformity, positive surface charge, and surface plasmon response. Colloidal stability was extensively investigated with respect to shelf-life over 6 months, temperature variation, pH, and interaction with proteins in cell culture media. Overall, the investigation confirmed the successful development of a stable positive complex with remarkable stability in biologically relevant test media containing proteins and electrolytes, and with a shelf-life exceeding 6 months. The excellent aqueous stability for this conjugate enhances its potential use as a test material for investigating interactions between positively charged NPs and bio-entities, as an antibacterial agent or a vehicle for drug delivery.