Ultrasensitive Human Urinary Albumin Detection via Composite Nanohydrogels

Albumin is an important biomarker in biological fluids and plays a critical role, particularly in the diagnosis of renal dysfunction. Therefore, the sensitive detection of low concentrations of albumin in urine is of great importance. In this study, a composite nanohydrogel modified with carbon dots has been developed for the selective detection of albumin from human urine. The composite nanohydrogels were synthesised using a molecular imprinting technique specifically designed to recognise albumin. Characterisation studies were conducted using ZetaSizer, SEM, EDX, CLSM and ATR-FTIR methods. The albumin-binding capacities of the carbon dots (C-Dots) and synthesised composite nanohydrogels were evaluated using fluorescence spectroscopy. The effects of different concentration conditions on binding efficiency were systematically investigated. Selectivity studies have shown that albumin-imprinted nanohydrogels can detect target molecule albumin four times more selectively than competitive molecules, Hb and IgG. Imprinting efficiency was estimated by comparing the signals of albumin obtained from non-imprinted and albumin-imprinted composite nanohydrogels. Finally, artificial urine samples mimicking real biological environment conditions were examined to evaluate matrix effect on the albumin detection. The repeatability and long-term stability of albumin detection, performed with four consecutive and six-month measurements, was evaluated using the %RSD value, confirming that the albumin determination performance was maintained.