Breaking barriers in soft material printing: High-fidelity DLP fabrication of silk sericin via height-adjusted curing and local error optimization

Abstract

Digital Light Processing (DLP) faces significant challenges in printing ultra-soft hydrogels due to their weak mechanical properties and the lack of robust accuracy evaluation systems. Here, we overcome these limitations by introducing silk sericin (SS) - a protein recovered from alkaline thermal degumming water - as a sustainable bioink. Through glycidyl methacrylate (GMA) modification, we developed methacrylated silk sericin (SerMA) with enhanced curability while preserving its inherent biocompatibility. A "Height Gradient Screening" approach was innovatively applied to the Jacob's working curve, enabling precise determination of cured depth under real-world printing conditions by addressing light scattering and self-focusing effects. Furthermore, we proposed the "Tangent Cylindrical Model", a novel framework to quantify localized printing errors across dynamic illumination source spacings, achieving resolutions as fine as 300 µm channel gaps and 400 µm hole structures-surpassing current capabilities for weak hydrogels. The printed SerMA constructs demonstrated excellent cytocompatibility (L929 cell viability>95 % over 168 h) and supported cell adhesion/spreading, validated via Live/Dead assays and F-actin staining. This work not only expands the DLP material library to include recovered, mechanically fragile proteins but also establishes a universal methodology for high-precision printing of soft biomaterials, with direct implications for tissue engineering, microfluidics, and biosensing.