Graphene Quantum Dots for Fluorescent Labeling of Gelatin-Based Shear-Thinning Hydrogels

The efficiency of injectable biomaterials as minimally invasive therapeutics significantly relies on biomaterial's characteristics, such as stability, biodegradation rate, and interaction with the host tissue, which requires real-time tracking of the biomaterials. Fluorescence imaging is considered as a noninvasive technique for monitoring biomaterials; however, the commonly used fluorescent agents are often accompanied by photobleaching and toxicity. Herein, graphene quantum dots (GQDs) are introduced as a biocompatible and stable fluorophore for imaging and noninvasive monitoring of a physically cross-linked injectable shear-thinning biomaterial (STB) of gelatin-silicate nanoplatelets. Silicate nanoplatelets and GQDs serve as the physical cross-linkers of gelatin making electrostatic interaction with gelatin chains. Different STB-GQDs formulations are assessed in terms of fluorescence intensity, injectability, thermal stability, and cellular biocompatibility. STB-GQDs with 0.06% GQDs, 6% solid material, and 50% silicate in the solid material show the strongest in vitro fluorescence and the highest thermal stability. In vivo monitoring of STB-GQDs is also achieved through fluorescent imaging where incorporated GQDs exhibit a robust and stable signal, suggesting their promising applications in long-term tracking of gelatin-based STBs.

Automated summary

Graphene quantum dots (GQDs) are introduced as a biocompatible and stable fluorophore for noninvasive monitoring of a physically cross-linked injectable shear-thinning biomaterial (STB) of gelatin-silicate nanoplatelets. Different STB-GQDs formulations are assessed in terms of fluorescence intensity, injectability, thermal stability, and cellular biocompatibility, with the most optimal formulation showing strong in vitro fluorescence and high thermal stability. In vivo monitoring of STB-GQDs through fluorescent imaging demonstrates robust and stable signals, highlighting their potential for long-term tracking of gelatin-based STBs.