Guobin Mao,Wenquan Peng,Songbai Tian,Jiao Zheng,Xinghu Ji,Zhike He
Herein, we developed a simple and sensitive method for the detection of protamine and trypsin by using a ratiometric fluorescent probe based on Rox-DNA functionalized CdZnTeS quantum dots (QDs). The Rox-DNA functionalized CdZnTeS QDs were prepared via one-pot method, which was simple, low-cost, and modification-free. Protamine can cause the aggregation of ratiometric fluorescent probe through electrostatic interaction and quench the fluorescence of CdZnTeS QDs. Then, the protamine could be hydrolyzed to small peptides by trypsin and the fluorescence of QDs was recovered. However, the fluorescence of Rox kept unchanged. The fluorescence intensity ratio was proportional to the concentration of protamine or trypsin. A good linear relationship (25–300 ng/mL for protamine and 2.5–50 ng/mL for trypsin) with low limit of detection (4.73 ng/mL for protamine and 0.87 ng/mL for trypsin) was obtained. Meanwhile, we observed different colors by the naked eye after the addition of different concentrations of protamine and trypsin, and the minimum detectable concentration was as low as 4 μg/mL for protamine and 40 ng/mL for trypsin, respectively. In addition, the ratiometric fluorescent probe exhibited good analytical performance in complex biological matrix. Therefore, the ratiometric fluorescent probe can be proposed as a simple and effective tool for the detection and visualization of dual proteins.
Guobin Mao,Qin Cai,Fubing Wang,Changliang Luo,Xinghu Ji,Zhike He
As the blood glucose concentration is an important clinical parameter of diabetes, the rapid and effective detection of blood glucose is very significant for monitoring and managing diabetes. Here, a facile method to prepare Rox-DNA functionalized CdZnTeS quantum dots (QDs) was developed. The Rox-DNA functionalized CdZnTeS QDs were prepared by a one-pot hydrothermal method through phosphorothioate DNA bound to QDs, which were employed as a ratiometric fluorescent probe for the rapid and sensitive detection of H2O2 and glucose. Compared with the traditional multistep construction of ratiometric fluorescent probes, this presented approach is simpler and more effective without chemical modification and complicated separation. The CdZnTeS QDs with green fluorescence is specifically sensitive to H2O2, while the red fluorescence of Rox is invariable. H2O2 is the product from the oxidation of glucose catalyzed by glucose oxidase (GOx). Therefore, a facile method to detect H2O2 and glucose with a detection limit of 0.075 μM for H2O2 and 0.042 μM for glucose was developed. In addition, this proposed probe has been employed for the detection of glucose in human serum with a satisfactory result. Moreover, this probe has been used for visual detection, and the health and diabetics can be distinguished by the naked eye. Meanwhile, this nanoprobe is also generalizable and can be extended to the detection of many other H2O2-mediated analytes.
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