Antimicrobial and Antiviral Activity of Silver-Containing Nanocomposites Formed by 3D Printing Technology

Silver nanoparticles have become the focus of numerous researchers to create efficient antimicrobial and antiviral agents due to their pronounced pharmacological effects, low toxicity to the human body and the environment, and high stability in extreme conditions. To create antimicrobial drugs with silver nanoparticles, matrices from polymers of both synthetic and natural origin are used. Biopolymer polylactide (PLA) is one of the most promising materials for 3D printing (additive production) due to its physicochemical and technological properties. The aim of the work was to study the antimicrobial and antiviral activity of silver-containing nanocomposites formed on the basis of PLA with the addition of chitosan or polyethyleneimine (PEI) by 3D printing technology. Methods. Peculiarities of the structural organization of silver-containing materials were investigated by the method of wide-angle radiography on an XRD-7000 diffractometer. The morphology of the samples was studied by transmission electron microscopy on a JEM-1230 instrument. Filament formation proceeded through melting PLA-AgPalm-PEI or PLA-AgPalm-chitosan films in an extruder at a temperature of T=160±1°С. Samples were formed from the obtained filaments using a 3D printer. Th e antimicrobial activity of silvercontaining nanocomposites was determined by the disk diffusion method against opportunistic pathogens S. aureus and E. coli. Cytotoxicity and antiviral activity were investigated using the MTT method and staining by gentian violet. Results. Analysis of wide-angle X-ray diffraction patterns of products formed by 3D printing technology at 160°C showed that PLA-Ag-PEI and PLA-Ag-chitosan materials contain metallic silver. Analysis of microphotographs of PLA-4%Ag-PEI and PLA-4%Ag-chitosan products formed by 3D printing technology showed that silver nanoparticles formed by adding chitosan as a reducing agent and stabilizer to the polymer matrix of PLA are much smaller than when using PEI. Silver-containing nanocomposite samples, such as filaments and products formed from PLA-4%Ag-PEI and PLA-4%Agchitosan films subjected to heat treatment and without heat treatment, show antimicrobial activity against test cultures of S. aureus and E. coli. It was found that nanocomposites based on PEI and chitosan do not show cytotoxic effects in MDCK and HEP-2 cultures. Nanocomposites of both types show a weak antiviral effect against adenovirus serotype 2; the reduction of infectious titer was 0.5 lgTCID50/mL. None of the studied nanocomposites showed antiviral action on the influenza virus model. Conclusions. The investigated silver-containing nanocomposites with a silver concentration of 4% by weight, formed by 3D printing technology from PLA-4%Ag-PEI and PLA-4%Ag-chitosan films, show antimicrobial activity against S. aureus and E. coli test cultures and antiviral activity on influenza A virus and human adenovirus and do not show a cytotoxic effect on cells. The obtained data allow us to state that the studied silver-containing nanocomposites are promising antimicrobial agents for use in various fields of medicine and the food industry.