Inhibition of double-stranded DNA templated copper nanoparticles as label-free fluorescent sensors for L-histidine detection

A simple, rapid and label-free fluorescent sensing strategy has been developed for the detection of L-histidine on the basis of the inhibition of double-stranded DNA (ds-DNA) templated copper nanoparticles (Cu NPs) by L-histidine. Fluorescent Cu NPs were formed within 5 min at room temperature by using random ds-DNA as a template. However, the fluorescence intensity decreased obviously in the presence of L-histidine. This was mainly ascribed to the strong interaction between L-histidine and Cu2+, which would hamper the effective formation of fluorescent Cu NPs, leading to low fluorescence intensity. Under the optimized conditions, the strategy exhibited sensitive and selective detection of L-histidine with a detection limit of 20 nM. In addition, the method was successfully applied in the detection of histidine in human urine samples. This method was cost-effective and convenient without any labels or complicated operations. Thus, it could offer a simple, rapid and sensitive fluorescent platform for the detection of L-histidine.