Design and optimization of a Cu-MOF@graphene oxide nanozyme for point-of-care colorimetric determination of sarcosine and H2O2.

Prostate cancer is a leading cause of tumor-related mortality worldwide, and there is a critical need for reliable biomarkers that enable early, accurate, and specific diagnosis. Sarcosine, a metabolic byproduct of glycine, has emerged as a potential biomarker for prostate cancer progression, but its low physiological concentration and interference from complex biological matrices make its detection analytically challenging. In this study, a copper-based metal-organic framework supported on graphene oxide (Cu-MOF@GO) was synthesized via a solvothermal method and used as a highly active peroxidase-like nanozyme for the colorimetric detection of hydrogen peroxide and sarcosine. The Cu-MOF was successfully anchored onto the graphene oxide surface, providing an exceptionally large surface area (1476.8 m2 g-1) and abundant catalytic sites, as confirmed by structural and surface characterization through FTIR, SEM-EDX, BET and XRD analyses. To optimize catalytic efficiency, a half-fractional Central Composite Design (CCD) was employed, leading to excellent correlation coefficients (R 2 > 0.999) for linear responses to hydrogen peroxide (0.5-1000 µM, with a detection limit of 0.15 µM) and sarcosine (0.5-250 µM, with a detection limit of 0.16 µM). The method also demonstrated strong potential for portable analysis using smartphone-based RGB color detection, showing high precision and recovery in spiked serum samples. This work presents a computationally guided approach for designing nanozymes with enhanced catalytic activity, offering a low-cost, rapid sensor with wide linearity, high sensitivity, and unique selectivity for sarcosine detection, making it promising for portable and point-of-care prostate cancer screening applications.