title: A gold nanocluster-based fluorescent probe for simultaneous pH and temperature sensing and its application to cellular imaging and logic gates.
abstract: Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated.
authors.affiliation: Department of Chemistry, National Sun Yat-sen University, Taiwan. tsengwl@mail.nsysu.edu.tw.
authors.forename: Yun-Tse
authors.initials: YT
authors.lastname: Wu
authors.forename: Chandirasekar
authors.initials: C
authors.lastname: Shanmugam
authors.forename: Wei-Bin
authors.initials: WB
authors.lastname: Tseng
authors.forename: Ming-Mu
authors.initials: MM
authors.lastname: Hiseh
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Tseng