Designing C-Fe-O bonded MIL-88B(Fe)/jasmine petal-derived-carbon composite biosensor for the simultaneous detection of dopamine and uric acid

C-Fe-O bonded MIL-88B(Fe)/carbon composite was designed to enhance the sensitivity and resolution for the simultaneous detection of dopamine (DA) and uric acid (UA) based on the “adsorption enhancement and distinguished potential regulation” strategy. Fe loaded Jasmine petal derived biocarbon (Fe-JPBC) was implanted in MIL-88B(Fe) through C-Fe-O bonding, resulting in a novel composite biosensor (MIL(Fe)/Fe-JPBC). MIL-88B(Fe) exhibited improved analyte capture ability via adsorption enhancement, which significantly enhanced signal sensitivity and lowered the limit of detection (LOD). In addition, the enhanced signal transmission capacity for DA and UA was attributed to the strong interface between MOF and Fe-JPBC via C-Fe-O bond. Interestingly, the presence of this unique interface showed different catalytic properties for the redox reaction of DA and UA, and broadened the oxidation potential discrepancy between them. The MIL(Fe)/Fe-JPBC biosensor therefore exhibited well-resolved potential peaks of 240 mV for DA and UA with respective LOD of 42.0 nM and 5.6 nM. Cyclic voltammetry, adsorption kinetics and molecular simulation results revealed that compared to DA, the utilization of MIL(Fe)/Fe-JPBC to detect UA was a reaction-controlled process with higher affinity and faster adsorption rate, leading to its much lower LOD than DA. MIL(Fe)/Fe-JPBC also exhibited high anti-interference and reproducibility in the detection of simulated and real serum samples. The novel strategy of adsorption enhancement and distinguished potential regulation via C-Fe-O bond for designing composite biosensors with significantly increased sensitivity and resolution for the simultaneous detection of DA and UA could be deemed of great potential on large applications.