Novel Nanocombinations of L-tryptophan and L-cysteine: Preparation, Characterization and Their Applications for Dye Decolorization, Antimicrobial and Anticancer Activities

Abstract Tungsten oxide WO3 nanoparticles (NPs) were prepared in a form of nanosheets with a homogeneous size and dimensions in one step through acid precipitation using a cation exchange column. The resulting WO3 nanosheets surface was decorated with one of the two amino acids (AAs) L-tryptophan (Trp) or L-cysteine (Cys) for their dye removal, antimicrobial, and antitumor activities. A noticeable improvement in the biological activity of WO3 NPs was detected upon amino acid modification compared to the original WO3. The prepared WO3-Trp and WO3-Cys exhibited strong dye removal activity toward methylene blue and safranin dyes with complete dye removal (100%) after 6 h. WO3-Cys NPs and WO3-Trp NPs revealed higher broad-spectrum antibacterial activity toward both G-ve and G+ve bacteria with strong antifungal activity toward Candida albicans. Anticancer results of the modified WO3-Cys and WO3-Trp NPs against various kinds of cancer cells including MCF-7, caco-2, and HepG-2 cells indicated that they have a potent effect in a dose-dependent manner with high selectivity to cancer cells and safety against normal cells. The expression levels of E2F2, Bcl-2 genes were found to be suppressed after treatment with both WO3-Cys and WO3-Trp NPs more than 5-FU-treated cells. While expression level of the p53 gene in all tested cells was evidently up-regulated after treatment by more than 5-8 folds as compared to untreated cells. The docking results confirmed the ability of both NPs to bind to P53 gene with relevant potency in binding to other tested gens and participation of cysteine SH-functional group in such interaction.