Sulfur nanoparticle-encapsulated MOF and boron nanosheet-ferrocene complex modified electrode platform for ratiometric electrochemical sensing of adriamycin and real-time monitoring of drug release

Abstract

This work developed a modified electrode platform for dual-channel applications in ratiometric electrochemical sensing and real-time monitoring of drug release. In the presence of cobalt ions and sulfur nanoparticles (SNPs), 2-methylimidazole was polymerized to form SNPs-encapsulated cobalt metal–organic framework (MOF), SNPs@MOF. Boron nanosheets (BNSs) were prepared through ultrasound-assisted liquid-phase exfoliation, followed by loading ferrocene (Fc) to form BNSs-Fc complex. A clean glassy carbon electrode (GCE) was modified with Nafion on the surface, followed by drop-casting of BNSs-Fc and SNPs@MOF to construct a modified electrode platform, SNPs@ MOF/BNSs-Fc/GCE. The morphologies, microstructures, spectra and properties of products were characterized systematically. The platform was used as a new ratiometric electrochemical sensor to detect adriamycin (ADR), due to stable Fc signal output and content-dependent ADR signal output during the electrochemical redox process of Fc and ADR. Under optimal conditions, the sensor can perform effective detection of ADR in a broad range of 0.01–10 μM, with a low limit of detection of 2 nM. The sensor was verified to possess high detection selectivity, sensitivity and stability, and enabled successful detection of ADR in biological fluid samples, indicating potential reliability and practicability. Besides, the prepared BNSs-ADR carriers in electrolyte solution have the capability of spontaneous and pH-regulatable release of ADR. By means of the platform-based sensor, linear relationships of ADR/Fc redox-peak current ratio (or concentration of released ADR) versus release time were well constructed, which thus realized ratiometric electrochemical real-time monitoring of ADR release by the sensor.