Nanoparticles used as carriers of drugs and other therapeutics are precisely synthesized, most often as colloids, and intended to be used in biomedical, agricultural, and environmental applications.  There are two broad approaches employed for the production of nanoparticles: top-down involving the milling or grinding of a larger bulk sized material into smaller spheroidal nanoparticles or bottom-up synthesis scheme using a seed growth mechanics from a molecular pre-cursor.  In either method, particles can subsequently be coated with stabilizing agents which promotes retention of size and shape, and in some applications, minimizes agglomeration which has been shown to decrease efficacy in terms of absorption and distribution in the host organism. In this study, we aimed to produce 20 nm spherical particles composed of copper, silver, or iron using both production schemes.  Each of the six produced nanoparticles were subsequently stabilized with three distinct surface stabilizing agents, i.e., surfactant (cetyltrimethylammonium bromide), polymer (polyvinylpyrrolidone), and acid (ascorbic acid). We also show that each of the nanoparticles exhibit inherent antibacterial properties, although at differing degrees of potency. Nanoparticles were characterized using spectroscopy (dynamic light scattering and light absorbance/transmission) as well as with microscopy (transition electron and atomic force microscopy). Light scattering data reveals hydrodynamic diameter, dispersity, and surface charge. Electron microscopy illustrates the particle shape, while AFM illustrates particle tomography. Ultraviolet/visible/infrared spectroscopy indicates surface functionality. The positively charged nanoparticles, those coated with surfactant, induced the most bacterial inhibition effects when compared against all other particle-types tested.

Bacterial inhibition efficacy analyses of nanoparticle production schemes for agricultural and environmental applications

ACS Fall 2021

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