Preparation of nanosilver/polymer composites and evaluation of their antimicrobial and antitumor effect

In this study, a copolymer (PVA-g-PEG) of polyethylene glycol (PEG) and polyvinyl alcohol (PVA) was synthesized by grafting PEG chains onto PVA backbone. PVA-g-PEG was used as the carrier to prepare the silver nanoparticles/polymer composite (AgNPs/PVA-g-PEG) using a "one-pot" biological method in the presence of grape seeds extract as a reducing and stabilizing agent. In order to highlight the effect of the copolymer, the homo-polymers PVA and PEG were applied as the carriers to prepare the corresponding composites - AgNPs/PVA, and AgNPs/PEG, respectively using the same method. The prepared AgNPs/polymer products were characterized by UV absorption spectroscopy (UV-vis), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the silver ions were successfully reduced by the grade seeds extract and the produced AgNPs are coated on the surface of AgNPs/PVA-g-PEG and AgNPs/PVA, but not for AgNPs/PEG. The prepared AgNPs are uniform and monodisperse, the particle size is small with mean diameter about 25.7 ± 2.3 nm and 54.2 ± 3.4 nm for AgNPs/PVA-g-PEG and AgNPs/PVA, respectively. The AgNPs/polymer composites exhibited superior antimicrobial effects against microorganisms (Escherichia coli and Staphylococcus aureus). AgNPs/PVA-g-PEG demonstrated a better performance than AgNPs/PVA. AgNPs/PVA-g-PEG had a minimum inhibitory concentration (MIC) of 1.3 μg mL^-1 and a minimum inhibitory concentration (MBC) of 2.4 μg mL^-1 against the microorganisms. For anti-tumor effect, AgNPs/PVA-g-PEG also demonstrated a high cytotoxicity to the colorectal cancerous cells HCT116 and SW620. The IC50 values of AgNPs/PVA-g-PEG for HCT116 and SW620 cell lines were 25.4 and 37.6 μg mL^-1, respectively, suggesting a good anticancer activity. All above results indicate that AgNPs/PVA-g-PEG composites have a significant potential for the control of microorganisms and inhibition of cancer cells.