Ultrasensitive Determination of Copper in Complex Biological Media Based on Modulation of Plasmonic Properties of Gold Nanorods

Accurate determination of copper in complex biological media such as cells is quite difficult, and an analytical strategy based on copper-modulated formation of core–shell gold nanorods is described. Selective and label-free sensing can be achieved by measuring the change in the localized surface plasmon resonance absorption. The technique can determine trace amounts of copper in human serum, urine, and red blood cells without or with minimal sample pretreatment. The Cu detection limits are 20.67 μM in human serum, 0.193 μM in human urine, and 3.09 × 10–16 g in a single cell. The advantages of the technique are the high selectivity, simple or no sample pretreatment, and label free. Boasting a practical detection limit down to 2 fM, only 103 red blood cells are needed to conduct the analysis and the technique may be extended to the detection of trace amounts of copper in a single cell.