In vitro study of folate-conjugated silver nanoparticles for enhanced anticancer activity

Nanotechnology is developing rapidly for its ability to modify metals to nanosize which, in general, changes the physical, chemical and optical properties of metals. In this paper, the authors used local bacteria from a chromite mine in Sabzevar, Iran, for quick and environmentally friendly biosynthesis of functional silver nanoparticles (AgNPs). The results presented the efficient conditions for AgNP biosynthesis through reduction of silver ions by the supernatant of an Enterobacter sp. strain. After biosynthesis, the AgNPs were cleaned by centrifugation, and samples were further analyzed by ultraviolet–visible spectroscopy, dynamic light scattering (DLS), X-ray diffraction and scanning electron microscopy. The refined AgNPs yielded the best absorbance at 409 nm; the DLS results showed uniform dispersion of nanoparticles, with a standard size of 25–35 nm. The functionality of nanoparticles with proteins was assessed during synthesis and analyzed by Fourier transform infrared spectroscopy. Furthermore, folic acid (folate) was adsorbed. The results revealed that the toxicity of the nanoparticles after folate adsorption on a breast cancer cell line increased and followed a concentration-dependent pattern. Furthermore, the activity of the biologically synthesized AgNPs against Agrobacterium tumefaciens, Pseudomonas aeruginosa, Escherichia coli and Streptococcus pneumoniae was greater than that of the chemically synthesized compound.