Simple Approach to Generate Fluorescent Quantum Dots/Gelatin Composite with Thermo-responsive and Reversible Sol-gel Transition

Stimuli-responsive sol-gel transitions of biopolymers triggered by stimuli (e.g., temperature, pH, light, and electric field) have received tremendous attention due to their potential applications in controlled release of drugs, tissue engineering, and new functional materials. Herein, we use a simple approach to generate a fluorescent composite of quantum dots/gelatin with reversible sol-gel transition triggered by temperature stimuli. We initially prepared the aqueous CdS quantum dots with clear yellow fluorescence by a single-step process. These CdS quantum dots can reserve their fluorescence after they were combined with gelatin. Specifically, rheological measurements and vial inversion tests both confirm that CdS quantum dots/gelatin composite can undergo reversible sol-gel transition initiated by temperature stimuli near physiological temperature. Furthermore, it is shown that loading, preservation and release of CdS quantum dots in aqueous medium can be controlled by adjusting the temperature to trigger the sol-gel transition of the composite. Consequently, it can be expected that this fluorescent quantum dots/gelatin composite with thermo-responsive and reversible sol-gel transition has promising applications in biomedical fields such as bioimaging, biosensing, and drug delivery.