Facile synthesis of ternary magnetic chitosan-graphene oxide composites for efficient extraction of urinary modified...

The accurate quantification of urinary modified nucleosides, promising non-invasive cancer biomarkers, is hindered by their trace concentrations and complex matrix interference. To overcome this challenge, we developed the facile synthesis of a novel ternary magnetic composite (MCS-100GO) by integrating chitosan (CS) and graphene oxide (GO) onto the magnetic core, utilized as adsorbent for magnetic solid-phase extraction (MSPE). The adsorbent leverages the combined effects of hydrogen bonding (from CS and GO) and π-π interactions (from GO) for highly efficient capture, while the magnetic core enables rapid and simple separation. Systematic optimization demonstrated exceptional performance for 3-methylcytidine (m³C) and 7-methylguanosine (m⁷G). The MCS-100GO composite achieved rapid adsorption equilibrium (3 min), high maximum adsorption capacities (0.7730 mg/g for m³C and 0.7561 mg/g for m⁷G). The developed MCS-100GO based MSPE-HPLC-MS/MS method, validated according to FDA guidelines, exhibited excellent sensitivity (LODs: 0.015-0.030 μg/L), a wide linear range (0.050-50 μg/L; R² > 0.9995), and high precision (RSD < 6.4 %). Furthermore, parallelism experiments with a coefficient of variation (CV) of 9.7 % confirmed no significant matrix effects. Compared to existing methods, this approach offers a superior balance of low adsorbent dosage, sensitivity, speed, presenting a promising and efficient strategy for high-throughput analysis of urinary nucleoside biomarkers.