Dual-Parameter Monitoring of HSA and ALT via Albumin-Responsive Carbon Dot Fluorescent Signal Amplification System

Abstract

Human serum albumin (HSA) and alanine aminotransferase (ALT) are critical biomarkers for monitoring various health conditions. Here, a novel dual-functional fluorescent nano-sensor platform was developed for monitoring of HSA and ALT using carbon dots (CDs) and Au@MnO₂ nano-heterojunction. Water-soluble red-emitting CDs were synthesized via a solvothermal method, which enabled direct HSA detection with exceptional sensitivity (LOD: 0.0104 mg/mL) and a wide linear range (0.013-3.3 mg/mL), while intracellular HSA imaging was simultaneously achieved. The Au@MnO₂ nano-heterojunction were further synthesized and achieved non-internal-filtering specific and efficient quenching of CDs fluorescence and Au@MnO₂-CDs fluorescence quenching system was designed for ALT detection by combining the specific interaction of tiopronin with Au@MnO₂ and ALT. Ultrahigh sensitivity (LOD: 0.00137 U/mL) across a broad dynamic range (0.00274-0.667 U/mL) was demonstrated by this system. The reliability of this nanosensor was established through recovery studies in serum matrices, thereby demonstrating the measurement accuracy and potential for diagnostic applications.