Passive inactivation of Candida parapsilosis in model indoor bioaerosol study using the visible photocatalytic activity of synthesized nanocomposite.

Bioaerosol contamination in the indoor environment has caused a slew of negative health effects and diseases. Hence, its inactivation and reduction are necessary. In this study, effective synthesis of Ag⁰_Iron oxide@GO nanocomposite was carried out using clove flower bud extract as a green reducing agent. The aqueous extract with high polyphenols—Tannin content (75.6 TAE, 41.8 TAE), and flavonoids (44,705 mg QE/Kg) group of compound were mainly responsible for reduction of metal salts to nanoparticles. Characterization using UV–VIS spectra, FTIR, and XRD revealed functionalization of graphene oxide, whereas SEM–EDX, HR-TEM imaging, and Scherrer's equation revealed the average size of Ag⁰NPs (54 nm) and Iron oxide (62 nm) nanoparticle coated on graphene oxide. The synthesized nanocomposite was tested for antifungal activity against most abundantly present yeast isolated from the indoor office environment. The isolated yeast was identified as Candida parapsilosis using fungal ITS rRNA sequencing. Similarly, ITS fungal metagenome sequencing was carried out for verification of the percent abundance of the microbiome in indoor air. Results revealed the predominance of phylum Ascomycota (69.64%). Within this phylum, the most abundant fungal species were found to be Candida parapsilosis (38.1%). This yeast is an opportunistic pathogen linked to nosocomial infections in hospitals. Enhanced inhibition of C. parapsilosis (zone of inhibition of 22 ± 0.8 mm) was observed when the nanocomposite was exposed to light, indicating effective visible photocatalytic activity. Results of growth curve experiments in the presence of nanocomposite were also in-line with that of antifungal studies. Thus, this experiment proves to have a potential application as a retrofitment of existing indoor air disinfection technology which will provide hygienic breathable air. [ABSTRACT FROM AUTHOR]