Aqueous multiphoton lithography with multifunctional silk-centred bio-resists

摘要

Silk and silk fibroin, the biomaterial from nature, nowadays are being widely utilized in many cutting-edge microanodevices/systems via advanced microanofabrication techniques. Herein, for the first time to our knowledge, we report aqueous multiphoton lithography of diversiform-regenerated-silk-fibroin-centric inks using noncontact and maskless femtosecond laser direct writing (FsLDW). Initially, silk fibroin was FsLDW-crosslinked into arbitrary two/three-dimensional microanostructures with good elastic properties merely using proper photosensitizers. More interestingly, silk/metal composite microanodevices with multidimension-controllable metal content can be FsLDW-customized through laser-induced simultaneous fibroin oxidation/crosslinking and metal photoreduction using the simplest silk/Ag⁺ or silk/[AuCl4]⁻ aqueous resists. Noticeably, during FsLDW, fibroin functions as biological reductant and matrix, while metal ions act as the oxidant. A FsLDW-fabricated prototyping silk/Ag microelectrode exhibited 10⁴-Ω⁻¹m⁻¹-scale adjustable electric conductivity. This work not only provides a powerful development to silk microanoprocessing techniques but also creates a novel way to fabricate multifunctional metal/biomacromolecule complex microanodevices for applications such as microanoscale mechanical and electrical bioengineering and biosystems.