Abstract:
Early sensitive and specific cancer biomolecule detection plays a vital role in life science and biosensor. Recently, nanozymes that exhibit enzyme mimicking catalytic activity have been immensely used in the molecular biosensor as an alternative to natural enzymes. Herein, A starch-assisted method has been reported for the synthesis of a novel class of carboxyl group-functionalized iron oxide nanoparticles(C-IONPs) that emerged peroxidase mimicking activity and follow Michaelis-Menten kinetics. Scanning electron and transmission electron microscopy analysis revealed that the nanoparticles possess a spherical shape with an average size of around 250 nm. Raman and X-ray photoelectron spectroscopy spectra reveal that the surface of the nanoparticles coated with the COOH group. C-IONPs can bind biomarkers in complicated mixtures, allowing for fast magnetic separation and improved electrochemical detection of cancer biomarkers, particularly for methylated DNA and exosomes from cancer cells. This study revealed that a straightforward approach for the direct isolation and measurement of disease-specific exosomes and methylated DNA was developed using C-IONPs. The Chronoamperometric analysis revealed that the approach has an excellent specificity for OVCAR3 cell-derived exosomes (linear dynamic range, 6.25 × 105 - 1.0×107 exosomes/mL; detection limit, 1.25 × 106 exosomes/mL) with a relative standard deviation of <5.0% (n=3). This approach is a promising candidate for the development of advanced exosome biosensing assays for various clinical applications. And a differential pulse voltammetric (DPV) examination of the electroactive indicator [Ru(NH3)6]3+ bound to the surface-adsorbed DNA yielded an electrochemical estimate of the amount of DNA adsorbed on the electrode surface, which correlates to the DNA methylation level in the sample. The assay could successfully detect as low as 5% differences in global DNA methylation levels with high reproducibility (relative standard deviation (% RSD) = <5% for n = 3). The method could also be used to detect different amounts of global DNA methylation in synthetic samples and cell lines in a reproducible manner. The approach does not require bisulfite treatment, does not rely on enzymes for signal creation, and can detect global DNA methylation without PCR amplification using clinically relevant amounts of sample DNA. This proof-of-concept technology could have been used in point-of-care settings for liquid biopsy-based global DNA methylation analysis.
