Transparent SilMA Hydrogel: Priming Microstructure Regulation for Real-Time Cell and Organoid Visualization

Methacryloylated silk fibroin (SilMA) hydrogels (SFH) are extensively utilized in biomedical fields; however, the inherent opacity restricts their further translational use in regenerative medicine, particularly during the real-time visualization of cellular behavior. Herein, we report a highly transparent silk fibroin hydrogel (TSFH) fabricated via a bioinspired glutaraldehyde (GA)-mediated crosslinking strategy that suppresses the conformational transition from random coil to β-sheet. Remarkably, TSFH preserves its microstructural integrity by preventing micropore fusion. Furthermore, it maintains a micropore wall thickness of 400-800 nm, which closely matches the wavelength of visible light, thereby minimizing light scattering and yielding a transparent hydrogel. Additionally, TSFH exhibits sustained structural stability for over 1 month, serving as an ideal basal substrate for organoid culture and enabling detailed observation of cellular and organoid behavior. These advances represent a significant innovation in the structural modification of silk fibroin, offering a stable and transparent hydrogel platform with broad potential in translational medicine.