Balanced electrostatic blending approach--an alternative to chemical crosslinking of Thai silk fibroin/gelatin scaffold

In tissue engineering, chemical crosslinking is widely used for conjugating two or more biomaterials to mainly control biodegradability and strength. For example, Thai silk fibroin/gelatin scaffold will offer mechanical strength from Thai silk fibroin and cell attraction from gelatin. However, chemical crosslinking requires crosslinking agent which could potentially pose negative impact from remaining trace amount of chemicals especially in medical application. Here we present an alternative approach to chemical crosslinking—a balance electrostatic blending approach. In this approach, two opposite charge biomaterials were selected for blending, with different ratios. Both materials were bound together with electrostatic force. The maximum binding was achieved when mixture electric potential approaches zero. In this work, we compared this approach with traditionally chemical crosslinking in terms of physical appearance, binding effectiveness, mechanical strength (in dry/wet conditions), in vitro biodegradation, and cell proliferation. We found that 50/50 weight ratio of Thai silk fibroin/gelatin scaffold had almost comparable properties to chemical crosslinked scaffold. It has similar appearance, binding effectiveness, and affinity for cell proliferation. For mechanical properties, even this approach yields lower dry compressive modulus compared with chemical crosslinking. But in wet condition, the compressive modulus from both methods is similar. However, the biodegradation time of non-crosslinked scaffolds is slightly faster than that of chemical crosslinked ones. These results demonstrate that a balance electrostatic approach is an alternative approach to chemical crosslinking when there is a concern of remaining trace amount of crosslinking agent in medical application.