3D bioprinting of collagen-based materials for oral medicine

Oral diseases have emerged as one of the leading public health challenges globally.Although the existing clinical modalities for restoration of dental tissue loss and craniomaxillofacial injuries can achieve satisfactory therapeutic results,they cannot fully restore the original complex anatomical structure and physiological function of the tissue.3D printing of biological tissues has gained growing interest in the field of oral medicine with the ability to control the bioink component and printing structure for spatially heterogeneous repairing constructs,holding enormous promise for the precise treatment of oral disease.Particularly,collagen-based materials have been recognized as promising biogenic bioinks for the regeneration of several tissues with high cell-activating and biocompatible properties.In this review,we summarize 3D printing methods for collagen-based biomaterials and their mechanisms.Additionally,we highlight the animal sources of collagen and their characteristics,as well as the methods of collagen extraction.Furthermore,this review provides an overview of the 3D bioprinting technology for the regeneration of the pulpal nerve and blood vessels,cartilage,and periodontal tissue.We envision that this technique opens up immense opportunities over the conventional ones,with high replicability and customized function,which can ultimately promote effective oral tissue regeneration.

Sustainable metal-free leather manufacture via synergistic effects of triazine derivative and vegetable tannins

Restrictions on heavy metals,especially chromium,have encouraged alternative tanning systems that can reduce environmental and human health risks from conventional chrome-based tanning.In this work,metal-free combination tanning was developed by using vegetable tannins and a triazine-based syntan containing active chlorine groups(SACC).Specifically,the relationship between leather performance(e.g.,hydrothermal stability and organoleptic properties)and technical protocols(e.g.,types and dose of tannins)was systematically established.The optimized protocol involving a unique procedure(i.e.,10%SACC pre-tanning,shaving,and 25%wattle tanning)endowed the leather with high shrinkage temperature(~92℃)and met the Chinese standards for shoe upper leather(QB/T 1873-2010).Our method not only produces zero chrome-containing solid wastes,but also uses~75%less tannin for leather manufacture.The excellent leather performance was ascribed to the synergistic effects,where SACC and wattle diffused into collagen fibrils and may bind to collagen via covalent,hydrogen and ionic bonding,locking the hierarchical structure of collagen from microfibrils to fiber bundles.Moreover,we summarized these findings and proposed a diffusion-binding-locking mechanism,providing new insights for current tanning theory.Together with the biodegradable spent tanning liquor,this approach will underpin the development of sustainable leather manufacture.

Pickering aqueous foam templating:a promising strategy to fabricate porous waterborne polyurethane coatings

Waterborne polyurethane(WPU)has been widely used as coatings in industrial fields ranging from wood,real/synthetic leather,and textiles,because it exhibits versatile performance,excellent eco-friendliness,and superior film-forming property.In terms of wearable products,compact WPU coatings often cause discomfort due to the intrinsic poor vapor transmission.

Metal-organic frameworks nanoswitch:Toward photo-controllable endo/lysosomal rupture and release for enhanced cancer RNA interference

Endo/lysosomal escape and gene release are two critical bottlenecks in gene delivery.Herein,a novel photo-controllable metal-organic frameworks(MOFs)nanoswitch is rationally designed for enhancing small interfering RNA(siRNA)delivery.One single laser triggers the“off-to-on”switching of MOFs nanocomplexes,inducing significant siRNA release accompanied by rapid MOFs dissociation into protonatable 2-methylimidazalo and osmotic rupturing Zn2+ions,which cooperatively contribute to remarkable endo/lysosomal rupture(∼90%).The simultaneous endo/lysosomal rupture and release enable a high spatio-temporal control on RNA interference for effective cancer therapy.Notably,the“off-to-on”switching also activates fluorescence recovery for real-time monitoring siRNA delivery.The nanoswitch could easily be extended to deliver other therapeutic agents(e.g.,DNA,protein,anticancer drug)for overcoming endo/lysosomal entrapment.