Prolonged inhibitory effects against planktonic growth, adherence, and biofilm formation of pathogens causing ventilator-associated pneumonia using a novel polyamide/silver nanoparticle composite-coated endotracheal tube.

Microbial cells can rapidly form biofilm on endotracheal tubes (ETT) causing ventilator-associated pneumonia, a serious complication in patients receiving mechanical ventilation. A novel polyamide with a good balance of hydrophilic/hydrophobic moieties was used for the embedment of green-reduction silver nanoparticles (AgNPs) for the composite-coated ETT. The films were conformal with a thickness of ∼ 17 ± 3 µm accommodating high loading of 60 ± 35 nm spherical-shaped AgNPs. The coated ETT resulted in a significant difference in reducing both planktonic growth and microbial adhesion of single and mixed-species cultures, compared with uncoated ETT (p < 0.05). A time-kill assay demonstrated rapid bactericidal effects of the coating on bacterial growth and cell adhesion to ETT surface. Biofilm formation by Pseudomonas aeruginosa and Staphylococcus aureus, commonly encountered pathogens, was inhibited by > 96% after incubation for 72 h. Polyamide/AgNP composite-coated ETT provided a broad-spectrum activity against both Gram-positive and Gram-negative bacteria as well as Candida albicans and prolonged antimicrobial activity.

Biocompatibility and mineralization activity of modified glass ionomer cement in human dental pulp stem cells.

Background/purpose: Fortilin is a multi-functional protein involved in several cellular processes. It has been shown promising potential to be a bioactive molecule that can be incorporated in the dental materials. This study aimed to compare the biocompatibility and mineralization activities of modified glass ionomer cement (Bio-GIC) and Biodentine by direct and indirect method on human dental pulp stem cells (hDPSCs). Materials and methods: Conventional glass ionomer cement (GIC), Bio-GIC (GIC supplemented with chitosan, tricalcium phosphate, and recombinant fortilin from Fenneropenaeus merguiensis), and Biodentine were examined in this study. Recombinant fortilin was purified and tested for its cytotoxicity by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. Human DPSCs were treated with different material eluate for particular time intervals. At given time points, viability of hDPSCs was examined using MTT assay and calcium deposition was assessed by Alizarin red staining assay. Comparisons of the data among groups were analyzed by analysis of variance and Tukey's multiple comparisons. Results: All test materials demonstrated no cytotoxicity. In addition, Bio-GIC promoted cell proliferation at 72 h. For direct and indirect method, cells treated with Bio-GIC demonstrated significantly higher calcium deposition than other groups (P < 0.05). Conclusion: Bio-GIC and Biodentine are not cytotoxic to hDPSCs. Bio-GIC demonstrates enhanced calcium deposition comparable to Biodentine. Bio-GIC may be further developed as a bioactive material for dentin regeneration.