A sensitive determination of morphine in plasma using AuNPs@UiO-66/PVA hydrogel as an advanced optical scaffold

In this study, a novel turn-on fluorescence nanoprobe structure has been developed by in situ synthesis and embedding of gold nanoparticles (AuNPs) and Zr-based metal-organic frameworks (MOFs), UiO-66, in polyvinyl alcohol (PVA) hydrogel for sensitive quantification of morphine in human plasma samples. A three-dimensional network of PVA hydrogel was formed by simultaneously penetrating UiO-66 and gold ions in the hydrogel frame and reducing to AuNPs without adding any reducing agent. The morphology and characterization of this new PVA-based nanocomposite hydrogel were studied by transmission electron microscopy, dynamic light scattering instrument, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. Based on weakened fluorescent intensity resulting from AuNPs binding with Zr node in UiO-66 within PVA matrix, AuNPs@UiO-66 part of the nanocomposite has been employed as a fluorescent sensing probe for selective detection of morphine. The subsequent turn-on of the biocompatible nanoprobe is dependent on the strong binding of morphine with AuNPs on the surface of the UiO-66 frameworks. This platform illustrates a linear calibration curve in the range from 0.02 to 2.0 μg mL^-1 with a detection limit of 0.016 μg mL^-1. The relative intra- and inter-day standard deviations of the nanoprobe for determinations of morphine were 0.84% and 0.69% (n = 5), respectively. It is particularly proper for precise morphine assay in complex samples like human plasma with good recoveries and acceptable results. Due to its portable, robust, and instrument-free characteristics, it is estimated to display superb prospective for on-site clinical monitoring.