Functionalization of metal-organic frameworks with metallic nanoclusters for ultra-sensitive monitoring of morphine in biological fluids

Abstract

A reliable, fast, and cost-effective method of monitoring morphine (MO) concentration in biological fluids is highly desired in clinical and modern medicine. Nanotechnology has opened up new possibilities for developing morphine biosensors, but the most advanced electrodes available offer a detection limit (LOD) of ≥10 nM. This work introduces a new, ultrasensitive electrochemical biosensor based on microporous metal-organic frameworks (∼1100 cm2 g−1 surface area) modified by Ag clusters (∼2 nm) and functionalized by Au nanoparticles (∼180 nm). Electrochemical studies show that functionalizing the microporous crystalline particles (620 ± 45 nm) with metal nanoclusters enhances charge transfer kinetics and electrochemical surface area by about 50 and 10 folds, respectively, resulting in high sensitivity (0.127 µA µM−1), broad linear dynamic range (0.05–600 µM), and low LOD (3 ± 0.2 nM). The differential pulse voltammetry confirms the stability (over 6 weeks), repeatability (RSD=3.0%), and reproducibility (RSD=4.0%) of the hybrid biosensor. The decent selectivity and specificity (RSD=7.4%) of the biosensor against various analogs co-existing with MO in urine have also been determined. Therefore, the hybrid metal-inorganic biosensor presents a promising prospect for simple, low-cost, and precise monitoring of biomolecules, including morphine, in biological fluids and clinical medicine.