Evaluation of antimicrobial properties of polymer nanocomposites for medical application

Abstract

The paper is devoted to the investigation of antimicrobial activity of polymer nanocomposites of both low-density polyethylene and nonwoven polymeric material (a mixture of woven and polyester fibers) that had been impregnated by Cu nanoparticles. The microorganisms were grown according to generally accepted microbiological rules and on media recommended for each bacteria family. Formation of biofilms of microorganisms was studied on the surface of microtiter plates for enzyme-linked immunosorbent assay. After incubation of microtiter plates, the culture medium was removed from the wells. The wells were rinsed five times with sterile distilled water. The plates were air dried for 45 minutes and each well was stained with 1% crystal violet solution in water for 45 min. After staining, the plates were washed with sterile distilled water five times. The quantitative analysis of biofilm production was done by adding 95% ethanol for discoloration of the wells. The research shows the antibacterial activity of Cu nanoparticles on planktonic forms of the investigated microorganisms, which prevented the formation of dense biofilms. With the use of low-density polyethylene impregnated by Cu the ability to form biofilms by planktonic cells of the referent strains of microorganisms was detected to decrease by 1.7 (Escherichia coli), 12.3 (Klebsiella pneumonia) times in the studied strains and with the use of nonwoven polymeric material treated by Cu nanoparticles, the ability to form biofilms decreased by 1.8 (Escherichia coli) – 21.8 (Klebsiella pneumonia) times in the studied strains. In subjecting the formed daily biofilms of referent strains of microorganisms to Cu nanoparticles, the destruction of biofilms of the studied strains of microorganism was observed as well as violation of the integrity of the biofilm monolayer and decrease of density index in comparison with control values. As a result, the obtained polymer nanocomposites can be recommended for preventive use in the fight against nosocomial infections. The practical relevance of this study lies in the possibility of reducing the incidence of purulent-inflammatory diseases and mycoses and, accordingly, reduction of the costs of treating these diseases.

Preliminary Study of the Bactericide Properties of Biodegradable Polymers (PLA) with Metal Additives for 3D Printing Applications

“…Furthermore, the bactericidal behavior of metal-based materials differs from species and often from strain for each bacterium [ 16 ]. Previous research focused on the antimicrobial mechanisms of metal-based polymers such as silver (Ag) [ 5 , 17 ], copper (Cu) [ 18 , 19 ], gold (Au) [ 20 , 21 ] or zinc (Zn) [ 22 ]. These works were carried out on different polymeric matrices and bacterial strains, analyzing the influence of different parameters on bacterial capacity, e.g., particle size: V. Tomas et al [ 17 ] evaluated the antibacterial effectiveness of hydrogels prepared with Ag nanoparticles tested on E. coli , verified that for smaller particle size, more contact with bacteria causing faster inhibition.…”

“…Another issue is the ratio between the bactericidal capacity and the intervening strain. O. V. Hopta et al [ 19 ] analyzed bacterial inhibition in low-density polyethylene composites with Cu nanoparticles and verified that bactericidal effectiveness depends on the bacterial family studied. On the other hand, the dispersion in the matrix and surface distribution of the material also influence behavior.…”

“…Considering that PLA polymeric compounds activated with silver ions coated with clay have not been tested for their microbial capacity in a whole production line and other studies [ 11 , 19 , 22 , 27 , 43 , 47 ] have demonstrated microbial activity in plastics, the present research proposes to study their effectiveness against Listeria monocytogenes and E. coli bacteria and to try to demonstrate that the proposed materials fit in the same microbial line.…”