Selenium nanoparticles stabilized by fungal chitosan with antibacterial activity – synthesis and characterization

Abstract

Soil samples were screened for fungal strains producing chitosan and the chitosan production by the potent isolate Aspergillus niger SS4 was observed to be optimum at 288 h, 36 °C, 5.7 pH, and 160 rpm by response surface method (RSM). The observed chitosan production was 42.3 gL−1 exceeded the predicted production of 41.654 gL−1. The fungal chitosan has a 27 kDa molecular weight and a 92.26% deacetylation degree (DD) level. Ascorbic acid and fungal chitosan were used to produce selenium nanoparticles (CS-SeNPs). UV-spectral study of CS-SeNPs indicated a peak at 310 nm. TEM with EDS analysis showed CS-SeNPs were spherical with an average size of 62.84 ± 5.91 nm and selenium was the main element. XRD showed crystalline CS-SeNPs, which have 17 mv zeta potential. FTIR revealed the nitrogen and carbon of selenium-chitosan linkages. The CS-SeNPs showed antibacterial efficacy against Gram-positive and Gram-negative bacteria, with the highest zone of inhibition (22.55 ± 0.40 mm) and the lowest minimum inhibitory concentration and minimum bactericidal concentration of 160 µg/mL and 320 µg/mL against Staphylococcus aureus (NCIM 2079). This study conclusively showed the efficient use of fungal chitosan as the stabilizing agent for the eco-friendly synthesis SeNPs with antibacterial activity to be used in biomedical sectors.