Two-step glutaraldehyde crosslinking for controlled micro-wrinkle formation on gelatin gel surfaces

Abstract

We developed a simplified method for introducing micro-wrinkles on gelatin gel surfaces using only glutaraldehyde as a crosslinking agent. Our two-step chemical crosslinking approach involves initial bulk gelation followed by additional surface crosslinking, creating an elastic modulus gradient between the surface and bulk. This gradient generates swelling pressure differences that induce spontaneous wrinkle formation. By systematically controlling glutaraldehyde concentrations and spin-coating speeds, we achieved precise control over wrinkle morphology, including dot, peanut, and T-shaped patterns. The elastic modulus ranged from 40 to 650 kPa, with corresponding changes in swelling ratios. Unlike previous photocrosslinking methods requiring sophisticated optical equipment, our approach offers a novel fabrication process using simple chemical reagents. This technique provides independent control of surface and bulk properties, enabling systematic design of wrinkled hydrogel surfaces for biomedical applications.