Facet-energy inspired metal oxide extended hexapod decorated with graphene quantum dots: Sensitive detection of bisphenol A in live cells

摘要： The development of crystal-facet metal oxide heterostructures has been of great interest owing to their rational design and multi-functioning properties at the nanoscale level. Herein, we report a facile solution-based method for the synthesis of single-crystal Cu2O nanostructures (i.e. Cu2O-CuO) as a core. The graphene quantum dots (GQDs) with varying concentrations are harvested on the surface of Cu2O extended hexapods (EHPs) in ethanol solution at room temperature via self-assembly, where copper acts as a sacrificial model and stabilizer as well. The Cu2O crystals displayed a good sensing activity toward BPA oxidation owing to high energy facets, dangling bonds and great proportion of surface copper atoms. The structural, morphological, chemical and vibrational investigations were attained in detail, presenting high crystallinity of the hybrid nanocomposite and Cu2O-CuO heterojunction positions along with the growth of GQDs on the core of Cu2O-CuO crystal. The electrochemical sensing performance of as-fabricated Cu2O-CuO@GQDs EHPs has been monitored for the determination of bisphenol A (BPA) as an early diagnostic marker and environmental contaminant. The synergy effect of boosted surface area, exposed Cu {111} crystallographic planes and mixed copper valences enhance redox reaction kinetics by increasing the electron shuttling rate at the electrode-analyte junction. Benefitted from the improved electrocatalytic activity for BPA oxidation, the electrochemical sensor displayed the lowest limit of detection (≤1 nM), good chemical stability and broad linear range (2 nM - 11 mM), and high sensitivity (636 μA mM-1 cm-2). The Cu2O-CuO@GQDs EHPs based sensing platform has been applied for BPA detection in water and human serum samples. We have also constructed up a pioneering electrochemical sensing podium for BPA detection in live cells which might be used as a marker in early disease diagnosis.