Nano-Micro Granular Ink with Modulatable Structure and Function Modules for Wound Dressing Preparation via 3D Printing

For porous dressing production through 3D printing, it is challenging to adjust the printability of ink while balancing its bioactivity. The present study introduces an example of a modular construction method for heterogeneous granular ink. Gelatin microspheres (gelatin-MSs) are assembled by poly (gallic acid)-coated zinc-containing nano-hydroxyapatite (ZnHA-NP/p(GA)), and further cooperate with Ag⁺ to form a kind of granular inks. The three modules including gelatin-MS, ZnHA-NP/p(GA), and Ag have their own functions: The viscoelastic gelatin-MS module is the essential component that realizes ink extrusion. The ZnHA-NP/p(GA) module not only forms reversible interactions with gelatin-MS that realize the assembly but also takes the responsibility of reactive oxygen species-scavenging and anti-inflammatory. The Ag module not only interacts with ZnHA-NP/p(GA) module to promote the stability but also exhibits strong antibacterial property. The gelatin-MS size, p(GA)-coating duration, ZnHA-NP/p(GA) content, and Ag content are optimized to yield a nano-micro granular ink for bioactive porous dressing preparation that is used to significantly promote the healing of refractory wounds. Therefore, this method allows particles with different structures and bio-functions that serve as modules to assemble into inks, realizing the balance of printability and biological functions for dressing manufacturing.