Determination of insulin with ultra-performance liquid chromatography tandem mass spectrometry enhanced by Mg-based micromotors.

An active drug delivery vector of Mg-based micromotor is proposed for enhanced intestinal drug mass spectrometry (MS) detection from proof of concept. Taking diabetes as a disease model, insulin nanoparticles (Ins-NPs) were successfully loaded in chitosan (CHI) layer of Mg-based micromotor (Mg/Au/PLGA/CHI@Ins-NPs) due to electrostatic adsorption with PLGA. The penetration ability of micromotors was evaluated on artificial mucin, which is distributed within about 300 μm of the mucus. In addition, in vitro drug delivery and retention was carried out on the isolated small intestine of mice; then, the insulin molecule was determined by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). By overcoming the mucus barrier and enhancing retention in intestine through active transport of micromotor, insulin ions at m/z 963.9443, 1156.3287, and 1445.1592 were detected by UPLC-MS and classified as [Insulin + 6H]6+, [Insulin + 5H]5+, and [Insulin + 4H]4+. Notably, the mass-to-charge ratio of insulin ions was detected only in micromotor drug delivery systems compared to drug-loaded inert particles in the isolated small intestine, attributed to the intensive penetration and retention capability of micromotors. Meanwhile, this Mg-based micromotor exhibited good biocompatibility and was easy to be removed for the UPLC-MS detection sample preparation. Overall, we provide a potential strategy to detect the low content of drugs with UPLC-MS technique by combining with active micromotor and further broadening the sensing application for untethered micromotor.