Silk fibroin microneedles fabricated by digital light processing 3D printing

In this report, one-step 3D structuring of protein-based microneedles is proposed using digital light processing (DLP) 3D printing. Such a technique is advantageous in direct 3D construction of molecules dissolved in aqueous solution at relatively low concentration. The DLP printing of silk fibroin (SF) as a safe protein-based microneedle is challenging, and use of riboflavin, an enzyme that acts as a photoinitiator, reduces the toxicity in biomedical applications. An anti-aliasing process produces SF microneedles with oblique features, while dehydration of the printed hydrogel enhances the sharpness of printed features. The flexibility of an SF microneedle array pad is investigated, and the delivery of molecules to the skin is verified using rhodamine B fluorescence dye.