Chitosan/MgO NPs/CQDs bionanocomposite coating: Fabrication, characterization and determination of antimicrobial efficacy.

The development of new polymer nanocomposites or antibacterial coatings is crucial in combating drug-resistant infections, particularly bacterial infections. In this study, a new chitosan polymer based nanocomposite reinforced with magnesium oxide nanopowders and carbon quantum dots was fabricated by sol-gel technique and coated on 316 L stainless steel. In order to gaining the optimal amount of components to achieve the maximum antibacterial properties, the effect of concentration of nanocomposite components on its antibacterial properties was investigated. Crystal structure, microstructure, elemental dispersion, size distribution, chemical composition and morphology of nanocomposite and coating were characterized with various analyses. The obtained results exhibited that the carbon quantum dot and magnesium oxide nanopowders were distributed uniformly and without agglomeration in the chitosan matrix and created a uniform coating. The antibacterial properties of the synthesized samples against Staphylococcus aureus bacteria (gram positive) were evaluated using disk diffusion and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) antibacterial tests. The inhibition growth zone formed around the antibiotic and nanocomposite 25 mg/ml under dark and light was about 32 and 14, 11 mm, respectively. Also, MIC and MBC values for final nanocomposite were 62.5 and 125 µg/ml, respectively.

Synthesis, characterization, and investigation of antibacterial activity of Novel CMC/CuO NPs/CQDs bionanocomposite coating.

In recent decades, healthcare-associated infections (HAIs) have become a common problem in healthcare facilities such as hospitals. As a result, researchers are currently developing nanocomposite coatings that are strengthened with antibacterial nanoparticles. In this research, a novel antibacterial bionanocomposite coating based on carboxymethyl cellulose polymer/copper oxide nanoparticles/carbon quantum dots was coated on medical grade 316 stainless steel by sol-gel dip-coating method. The effect of the concentration of nanocomposite components was investigated at four different levels to determine the best ratio with the most antibacterial activity. Structural characteristics of nanocomposite and coating were investigated using different analysis methods. The coating analysis showed that reinforcements are uniformly distributed in the polymer matrix. Antibacterial test of disc diffusion was performed by the Kirby-Bauer method and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) antibacterial test. The results showed that bionanocomposite was effective in the MIC assays against Staphylococcus aureus and Escherichia coli with MIC values of 25 mg/ml and >50 mg/ml, respectively. The inhibition zones for E. coli and S. aureus were 17 and 32 mm, respectively, at 10 µg/disc of gentamicin. SEM images displayed significant and evident alterations in the structure of bacterial morphology, indicating cellular damage.