A visual physiological temperature sensor developed with gelatin-stabilized luminescent silver nanoclusters

•Gelatin was firstly used as protective and reducing agent to prepare Ag nanoclusters.•The preparation of Ag nanoclusters could be completed within 4 h at room temperature.•A temperature sensor was developed with gelatin-stabilized Ag nanoclusters.

A visual physiological temperature sensor was successfully developed with newly hydrothermally prepared fluorescent silver nanoclusters (AgNCs) at room temperature using gelatin as the protective and reducing agent. The as-prepared gelatin-stabilized AgNCs was water-soluble, uniform and exhibited a narrow distribution with an average size of 1.16 nm, showing a maximum emission band at 552 nm (2.45 eV) when excited at 445 nm (2.79 eV). The large Stokes shift of 110 nm of the gelatin-stabilized AgNCs makes it actually applicable with very low background and light scattering interferences. It was found that the as-prepared gelatin-stabilized AgNCs is temperature-sensitive over the range from 5 °C to 45 °C, and thus a visual physiological temperature sensor could be developed with the gelatin–AgNCs as under the irradiation of visible light.

Graphical abstractA direct synthesis strategy of water-soluble and fluorescent Ag nanoclusters (AgNCs), using gelatin as protective and reducing agent, has been established in this report. The AgNCs were successfully prepared within 4 h at room temperature. Notably, the gelatin–AgNCs were further applied to be a reversible and sensitive temperature sensor.Figure optionsDownload full-size imageDownload as PowerPoint slideFigure optionsDownload full-size imageDownload as PowerPoint slide