Effect of Green Light on Citrate-Coated Gold Nanoparticles and Their Effect on the Growth of Cellulolytic Fungi

The design and study of gold nanoparticles (AuNPs) with improved catalytic properties is of great interest due to the wide range of applications, so the modification of the surface of nanoparticles by coating with organic functional groups, as well as the treatment of these coatings with a light beam, is investigated as a potential nanotechnological tool in this regard. We obtained fine gold nanoparticles (AuNPs) by the conventional method with pH adjustment and by green light irradiation of pristine gold–citrate nanoparticles. The physicochemical properties of these products were revealed by electron microscopy, dark-field optical microscopy, UV-Vis spectrophotometry, dynamic light scattering and cyclic voltammetry. The phenomena at the interface between pristine colloidal nanoparticles and those exposed to green light with environmental fungi were analyzed at the level of the cellulolytic species of Chaetomium globosum, considering the final fate in the biosphere of gold nanoparticles used in the technical and biomedical fields. Measurements of fungal growth in the presence of 200 to 1000 µL/L of AuNP suspensions (or Au content of 0.098 to 0.49 µg/mL) provided semi-quantitative information on their nanotoxicity, focusing on the comparison between non-irradiated and green-light-exposed gold nanoparticles.