Biosynthetic gold nanoparticles (bAuNPs) present a promising avenue for enhancing bio-compatibility and offering an economically and environmentally responsible alternative to traditional production methods, achieved through a reduction in the use of hazardous chemicals. While the potential of bAuNPs as anticancer agents has been explored, there is a limited body of research focusing on the crucial physicochemical conditions influencing bAuNP production. In this study, we aim to identify the optimal growth phase of Pseudomonas aeruginosa cultures that maximizes the redox potential and coordinates the formation of bAuNPs with increased efficiency. The investigation employs 2,6-dichlorophenolindophenol (DCIP) as a redox indicator. Simultaneously, we explore the impact of temperature, pH, and incubation duration on the biosynthesis of bAuNPs, with a specific emphasis on their potential application as antitumor agents. Characterization of the resulting bAuNPs is conducted using ATR-FT-IR, TEM, and UV-Vis spectroscopy. To gain insights into the anticancer potential of bAuNPs, an experimental model is employed, utilizing both non-neoplastic (HPEpiC) and neoplastic (PC3) epithelial cell lines. Notably, P. aeruginosa cultures at 9 h/OD600 = 1, combined with biosynthesis at pH 9.0 for 24 h at 58 °C, produce bAuNPs that exhibit smaller, more spherical, and less aggregated characteristics. Crucially, these nanoparticles demonstrate negligible effects on HPEpiC cells while significantly impacting PC3 cells, resulting in reduced viability, migration, and lower IL-6 levels. This research lays the groundwork for the development of more specialized, economical, and ecologically friendly treatment modalities.

Colorectal cancer (CRC) is the third most common cancer diagnosed today and the third leading cause of death among cancer types. CRC is one of the gastrointestinal tumors with obesity as the main extrinsic risk factor, since, according to authors, the meta-inflammation sustained by the excess adipose tissue can provide abundant circulating lipids, as well as hormones and metabolites crucial to tumor development and aggressiveness. The gut microbiota can protect the colon from meta-inflammation and endocrine changes caused by obesity. The present study aimed to investigate the antitumor activity of a commercial probiotic in intestinal tumor cells under two adiposity conditions. Experimental assays were performed on the Caco2 cell line (colon adenocarcinoma) supplemented with differentiated adipocyte’s secretomes of the 3T3-L1 cell line (mouse pre-adipocytes) in two adiposity conditions: (i) differentiation without the use of Pioglitazone (noPGZ) and (ii) differentiation using Pioglitazone (PGZ). The Caco2 cells were first exposed to both secretomes for 24 h and evaluated and subsequently exposed to probiotic extract followed by secretome and evaluated. The effects of these treatments were evaluated using cytotoxicity assays by MTT, cell migration by injury, and antioxidant activity by glutathione assay. The use of secretomes showed a statistically significant increase in cell viability in Caco2 cells, either in noPGZ (p < 0.01) or PGZ (p < 0.05), and the probiotic was not able to reduce this effect. In the injury assay, secretome increased cell migration by more than 199% in both adiposity conditions (p < 0.001 in noPGZ and p < 0.01 in PGZ). In the probiotic treatment, there was a reduction in cell migration compared to the control in adiposity conditions. The antioxidant response of Caco2 cells was increased in both adiposity conditions previously exposed to the probiotic supernatant. This pilot work brings to light some findings that may answer why the modulation of the intestinal microbiota using probiotics is an alternative strategy leading to improvements in the condition and stage of the colon tumor. Additional studies are needed to clarify the role of Pioglitazone in this type of tumor and the metabolites of obesity that are attenuated by the use of probiotics.