Assessment of Antioxidant Effect of Beta-Glucan on the Whole Blood Oxidative DNA Damage with the Comet Assay in Colorectal Cancer.

OBJECTIVE: The present study aims to evaluate the antioxidant effect of beta-glucan on oxidative DNA damage by comet assay. METHODS: A total of 19 adult females and males diagnosed with stage 3-4 colorectal cancer and a control group of 20 age-matched healthy subjects were enrolled in the study. Blood samples of the participants were analyzed using Comet Assay for the parameters of DNA damage. RESULTS: Significantly increased DNA damage was observed in patients versus the control group as indicated by greater values of tail moment, tail percent DNA and tail length. Following incubation with ß-glucan, a substantial reduction was found in the aforementioned parameters of DNA damage. Comet assay revealed significant levels of endogenous DNA damage in patients as shown by remarkable increases in the tail moment, the percentage of DNA in the tail and the tail length values, in comparison with the control group. Following treatment of fresh whole blood with ß-glucan incubation, DNA damages were significantly reduced, but lower values were observed after ß-glucan incubation in the patient group versus control group. CONCLUSION: ß-Glucan was found to reduce DNA damage substantially in colorectal cancer patients and show antimutagenic effects. Our results suggested that dietary ß-glucan intake might be important in the genesis of colorectal cancer tumors.

Aggregation-resistant nanozyme containing accessible magnetite nanoparticles immobilized in monodisperse-porous silica microspheres for colorimetric assay of human genomic DNA.

Bridging-induced aggregation of individual nanozyme particles by long-chain biomacromolecules causes loss of peroxidase mimetic activity for various nanozymes. When a common nanozyme (Fe3O4 nanoparticles) was used for colorimetric assay of a long-chain biomacromolecule, human genomic DNA (hgDNA, 14.000 kDa, containing 22 kilobases), peroxidase-like activity was absent owing to the irreversible aggregation of Fe3O4 nanoparticles in the presence of hgDNA. We synthesized an aggregation-resistant nanozyme containing Fe3O4 nanoparticles immobilized in 5.1 µm monodisperse-porous silica microspheres. Fe3O4 nanoparticles were immobilized in a form accessible to the substrate and large biomolecules in the solution within the monodispersed silica microspheres including both mesopores and macropores. An appreciable and stable spectrophotometric response was obtained, originating from the satisfactorily high peroxidase-like activity of the synthesized nanozyme. No aggregation was observed in the aqueous dispersion of the nanozyme in the presence of hgDNA. Large particle size, low particle number density, high surface area, and the presence of macropores were evaluated as factors contributing to the adsorption of hgDNA chains onto the synthesized nanozyme without interparticle bridge formation between the individual microspheres causing aggregation. Here, for the first time a colorimetric assay was developed based on the enhancement of peroxidase-mimetic activity of non-aggregated porous silica microspheres to determine hgDNA concentration up to 300 ng/µL. hgDNA could be also isolated with 47% yield and an equilibrium hgDNA adsorption of 19.000 ng/mg, using the same nanozyme. Hence, a material acting as a nanozyme for colorimetric determination of hgDNA was also evaluated as a magnetic, solid phase extraction sorbent for the first time.