Synthesis and characterization of marine seagrass (Cymodocea serrulata) mediated titanium dioxide nanoparticles for antibacterial, antibiofilm and antioxidant properties.

Cymodocea serrulata mediated titanium dioxide nanoparticles (TiO2 NPs) were successfully synthesized. The XRD pattern and FTIR spectra demonstrated the crystalline structure of TiO2 NPs and the presence of phenols, flavonoids and alkaloids in the extract. Further SEM revealed that TiO2 NPs has uniform structure and spherical in shape with their size ranged from 58 to 117 nm. Antibacterial activity of TiO2 NPs against methicillin-resistant Staphylococcus aureus (MRSA) and Vibrio cholerae (V. cholerae), provided the zone of inhibition of 33.9 ± 1.7 and 36.3 ± 1.9 mm, respectively at 100 µg/mL concentration. MIC of TiO2 NPs against MRSA and V. cholerae showed 84% and 87% inhibition at 180 µg/mL and 160 µg/mL respectively. Subsequently, the sub-MIC of V. cholerae demonstrated minimal or no impact on bacterial growth at concentration of 42.5 µg/mL concentration. In addition, TiO2 NPs exhibited their ability to inhibit the biofilm forming V. cholerae which caused distinct morphological and intercellular damages analysed using CLSM and TEM. The antioxidant properties of TiO2 NPs were demonstrated through TAA and DPPH assays and exposed its scavenging activity with IC50 value of 36.42 and 68.85 µg/mL which denotes its valuable antioxidant properties with potential health benefits. Importantly, the brine shrimp based lethality experiment yielded a low cytotoxic effect with 13% mortality at 100 µg/mL. In conclusion, the multifaceted attributes of C. serrulata mediated TiO2 NPs encompassed the antibacterial, antioxidant and anti-biofilm inhibition effects with low cytotoxicity in nature were highlighted in this study and proved the bioderived TiO2 NPs could be used as a promising agent for biomedical applications.

Biologically synthesized copper oxide nanoparticles enhanced intracellular damage in ciprofloxacin resistant ESBL producing bacteria.

Copper oxide nanoparticles (CuO NPs) were synthesized biologically using leaf extract of Camilla japonica. The typical UV-visible spectral peak of CuO NPs was observed at a wavelength of ∼290 nm, which confirmed their successful synthesis. From scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses, the synthesized CuO NPs were found to possess spherical shape. Energy dispersive X-ray analyzer (EDX) results revealed that the CuO NPs are almost pure with atomic percentages of 50.92 for Cu and 49.08 for O. Fourier transform infrared (FTIR) confirmed the presence of an absorption peak located at a wavenumber position of ∼480 cm-1 typical for highly pure CuO NPs. TEM images displayed that the particles are relatively uniform in size ∼15-25 nm. The P. aeruginosa and K. pneumonia showed complete resistance against Hexa 077 antibiotic discs. The result of ≤22 ceftazidime and ≤27 cefotaxime confirmed that both the uropathogens were ESBL producers. The ≥8 mm of the MIC stripe further confirmed that both the uropathogens were ESBL producers. Furthermore, the antibacterial activity of CuO NPs against selected ESBL producing P. aeruginosa and K. pneumoniae at minimum inhibition concentration (MIC) of 100 µg/mL. The decreased cell viability and damaged membrane construction of both the uropathogens were observed by confocal laser scanning microscope (CLSM) using AO/EB stains at desired MIC dose. The morphological damage of the bacterial cells was demonstrated by SEM analysis. Hence, based on the above in vitro findings, the results suggested that the CuO NPs are efficient antibacterial compounds against ESBL producing bacteria, and that the plant leaf mediated CuO NPs can be considered as novel and promising material to act against various infectious bacteria.