【Device Papers】Enhanced Charge Transfer in Noble-Metal-loaded Gallium Oxide for Selective Electrochemical Sensing of Heroin and Morphine in Biological Matrix

      Researchers from National Forensic Sciences University have published a dissertation titled " Enhanced Charge Transfer in Noble-Metal-loaded Gallium Oxide for Selective Electrochemical Sensing of Heroin and Morphine in Biological Matrix " in Materials Today Nano.

Abstract

      The electrochemical detection of opioids such as heroin and morphine remains a critical challenge in forensic and biomedical analysis. In this work, metal-decorated gallium oxide (Ga₂O₃) nanomaterials were synthesized via a solvent-mediated approach, in which water was found to be a superior solvent over ethylenediamine, yielding well-defined nanorods within the nanometer range. Electrochemical impedance spectroscopy revealed that the smaller, water-synthesized nanoparticles exhibited lower charge-transfer resistance (0.59 kΩ), indicating more efficient charge transfer. This nanometer-range morphology was therefore identified as optimal for the electrochemical sensing of heroin and morphine. Calcination of the synthesized materials promoted the formation of the thermodynamically stable β-Ga₂O₃ phase, thereby enhancing the electrochemical activity of the resultant nanostructures. Copper (Cu), palladium (Pd), silver (Ag), and gold (Au) were systematically loaded onto the surface of the Ga₂O₃ host framework, forming metal-Ga₂O₃ heterojunctions; Au and Ag produced discrete nanoparticle-decorated rod morphologies, while Pd and Cu formed evenly dispersed, spherical particle morphologies on the Ga₂O₃ surface. Comprehensive characterization by XRD, TEM, SEM, TGA, and XPS confirmed phase purity, morphology, thermal stability, and elemental composition of all materials. Among the synthesized composites, the silver-loaded gallium oxide modified glassy carbon electrode demonstrated the best electrochemical performance and enabled sensitive differential pulse voltametric detection of heroin (LOD =0.175 μM) and morphine (LOD = 0.42 μM) at physiological pH 7. Interference studies with common cutting agents such as caffeine, alprazolam, and paracetamol confirmed strong selectivity with negligible cross-reactivity in complex matrices. Real-sample analysis of urine further validated the sensor's practical utility, demonstrating effective and reliable opioid detection under biologically relevant conditions.

DOI：

https://doi.org/10.1016/j.mtnano.2026.100923