Although carbon nanoparticles or quantum dots (C-dots) have been studied extensively for a variety of applications (e.g., photocatalysis, metal ion sensing, antibacterial, cell labeling), a greener synthetic method is highly indispensable. Herein, we report a facile one-step hydrothermal carbonization approach for the synthesis of fluorescent blue/green C-dots using oyster mushroom (Pleurotus species). First, we demonstrate the application of these C-dots as a colorimetric sensor for toxic metal ions detection such as heavy metal Pb2+ ions with the limit of detection (LOD) and limit of quantification (LOQ) of 58.63 μM and 177.69 μM, respectively. Second, we show the application of C-dots as a promising fluorescent probe for DNA recognition through the electrostatic intercalative interaction between ctDNA and C-dots. Third, we demonstrate the efficient antibacterial activity of C-dots against three bacterial strains (Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa). Finally, the anticancer activity of C-dots against MDA-MB-231 breast cancer cells is demonstrated.

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The polycyclic aromatic hydrocarbons (PAHs) biodegradation potential of the five basidiomycetes' fungal monocultures and their cocultures was compared with that of a Pseudomonas isolate recovered from oil-spilled soil. As utilization of hydrocarbons by the microorganisms is associated with biosurfactant production, the level of biosurfactant production and its composition by the selected microorganisms was also investigated. The Pseudomonas isolate showed higher ability to degrade three of the five PAHs but the isolate did not produce biosurfactant higher than C. versicolor and P. ostreatus. Among the PAHs, the most effective biodegradation of PAH--pyrene (42%)--was obtained with the fungus C. versicolor. Cocultures involving the fungi and Pseudomonas could not significantly degrade the selected PAHs compounds above that degraded by the most efficient monoculture. A slight increase in pyrene degradation was observed in cocultures of C. versicolor and F. palustris (93.7% pyrene). The crude biosurfactant was biochemically characterized as a multicomponent surfactant consisting of protein and polysaccharides. The PAH biodegradation potential of the basidiomycetes fungi positively correlated with their potential to express ligninolytic enzymes such as lignin peroxidase (Lip), manganese peroxidase (Mnp), and laccase. The present study utilized in silico method such as protein-ligand docking using the FRED in Open Eye software as a tool to assess the level of ligninolytic enzymes and PAHs interactions. The in silico analysis using FRED revealed that of the five PAHs, maximum interaction occurred between pyrene and all the three ligninolytic enzymes. The results of the in silico analysis corroborated with our experimental results showing that pyrene was degraded to the maximum extent by species such as C. versicolor and P. ostreatus.

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