2D-fluorescence sensor array for protein identification under various osmolyte and pH conditions

Traditional chemical sensor arrays require multiple probes as sensing elements, making their construction complex and costly. To address this limitation, we designed a simple and sensitive two-dimensional fluorescence sensor array for protein identification. The sensor array employs six pH buffer solutions and two osmolytes as sensing elements, with CdSe/ZnS quantum dots (QDs) serving as fluorescent probes. Proteins in different pH environments exhibit variations in surface charge and three-dimensional conformation, which are further amplified by the addition of osmolytes. These enhanced differences result in distinct fluorescence response patterns through differential protein-QD interactions. Using linear discriminant analysis (LDA), 13 proteins were accurately classified. The sensor array was further applied to discriminate protein mixtures and proteins at different concentrations. These results indicate that the proposed sensor array provides a simple, rapid, and cost-effective strategy with promising applications in clinical diagnostics and proteomics.