Waste tire rubber (WTR) is hard to transform naturally because of the stable crosslinked structure of rubber material, resulting in environmental problems. Here, I investigated the biological desulfurization mechanism of WTR by Acidithiobacillus strains (Acidithiobacillus thioxidans and Acidithiobacillus ferrooxidans) by the size of crushed WTR. The surface chemical groups of desulfurizated waste tire rubber (DWTR) were analyzed by FTIR-ATR and XPS. FTIR-ATR data exhibited C=C bonds (1540 cm-1) decreased after desulfurization. XPS data showed S-O, S-S, and S-C bonds were remarkably decreased on the surface of DWTR. Also, I confirmed desulfurization between WTR and DWTR by DTNB assay and SO42- ion measurement. Taken together, Acidithiobacillus species break the crosslinked disulfide bonding on the surface of WTR, resulting in sulfoxide, sulfone, and sulfate ions.
Bacterial infection is one of the most common and universal cause of disease spreading associated with medical and surgical environment. Antimicrobial function of plasticized polyvinyl chloride (PVC) will be useful for making hygienic environments. Here, I synthesized the PVC composite by the addition of inorganic bacteriocide containing silver, zinc, and zeolite. And I investigated the growth inhibition rate for Staphylococcus aureus and Klebsiella pneumoniae which were analyzed in the presence of PVC composite with different doses of inorganic bacteriocide (0~20 wt%). Bacterial proliferation was significantly inhibited by 3 wt% of inorganic bacteriocide containing PVC composite. And I found the inhibition of bacterial biofilm formation by 5 wt% of inorganic bacteriocide containing PVC composite by the observation of scanning electron microscopy (SEM). Our data suggested that the antimicrobial effect of inorganic bacteriocide was caused by disturbing the bacterial biofilm formation.
SH-SY5Y cells were exposed to neat PVC, PVC/IB/ATH composite surface for 12 h and cell survival was assessed by MTT assay, LDH assay and caspase 3/7 assay. SH-SY5Y cells exhibited approximately 97.4% viability on neat PVC and 96.6% viability on PVC/IB/ATH composite compared with cell culture plate surface. The effects of PVC/IB/ATH composite could also be confirmed by the morphological observation and fluorescence image stained with Calcein-AM and propidium iodide. Fluorescence data exhibit the PVC/IB/ATH composite did not influence the shape of the cells in comparison to control. The results show that PVC/IB/ATH composite can be a good candidate for the application to the fabrication of surgical material, industrial environment, and study of polymer chemistry.