The application of Au nanoclusters in the fluorescence imaging of human serum proteins after native PAGE: Enhancing detection by low-temperature plasma treatment

▸ The sensitivity of this Au NC-based fluorescence imaging detection method is 7–14 times higher than that of traditional staining detection methods. ▸ Some relatively low abundance proteins are easily detected. ▸ This fluorescence imaging method can distinguish between the serum samples of patients with liver diseases and those of healthy people. ▸ This fluorescent-based method is simple, “green” and stable. ▸ LTP treatment for Au clusters is effective in the enhancement of fluorescence imaging. Proteins in human serum are increasingly being studied for their roles in a wide variety of biochemical interactions. To improve the sensitivity of the detection of human serum proteins after native polyacrylamide gel electrophoresis (PAGE), we have developed a fluorescence imaging detection technique for the detection. BSA (bovine serum albumin)-stabilized Au nanoclusters (NCs) were applied as fluorescent probes for imaging, and low-temperature plasma (LTP) treatment of the Au NCs was introduced to enhance the fluorescence imaging. Here, a series of optimization experiments (e.g. those to optimize for pH) were conducted for protein detection after 1-DE and 2-DE, and several types of discharge gases (He, O2, and N2) were selected for the LTP treatment. The possible mechanism of interaction between the proteins and the Au NCs was demonstrated by an isothermal titration calorimetry experiment. Using the present method, a sensitivity of 7–14 times higher than that of traditional staining detection methods was observed in the oxygen LTP-treated Au NCs fluorescence images, and some relatively low abundance proteins (identified by the MS/MS technique) were easily detected. In addition, this fluorescence imaging method was applied to distinguish between the serum samples of patients with liver diseases and those of healthy people. Thus, this fluorescence imaging method is suitable for the highly sensitive detection of various serum proteins, and it shows potential capabilities for clinical diagnosis.