Increasing demands for optical anticounterfeiting technology require the development of versatile luminescent materials with tunable photoluminescence properties. Herein, a number of fluorescent carbon‐ and oxygen‐doped hexagonal boron nitride (denoted as BCNO) phosphors are found to offer a such high‐tech anticounterfeiting solution. These multicolor BCNO powders, developed in a two‐step process with controlled annealing and oxidation, feature rod‐like particle shape, with varied luminescence properties. Studies of the optical properties of BCNO, along with other characterization, provide insight into this underexplored material. Anticounterfeiting applications are demonstrated with printed patterns which are indistinguishable to the naked eye under visible light but become highly…
One of the latest trends in the regenerative medicine is the development of 3D-printing hydrogel scaffolds with biomimetic structures for tissue regeneration and organ reconstruction. However, it has been practically difficult to achieve a highly biomimetic hydrogel scaffolds with proper mechanical properties matching the natural tissue. Here, bacterial cellulose nanofibers (BCNFs) were applied to improve the structural resolution and enhance mechanical properties of silk fibroin (SF)/gelatin composite hydrogel scaffolds. The SF-based hydrogel scaffolds with hierarchical pores were fabricated via 3D-printing followed by lyophilization. Results showed that the tensile strength of printed sample increased significantly with the addition of BCNFs in…
In the present work, dissolved cellulose has been 3D bioprinted to produce complex structures with ordered interconnected pores. The process consists of the dissolution of dissolving pulps in N-methylmorpholine-N-oxide (NMMO), multilayered dispensing, water removal of NMMO and freeze-drying. 3D bioprinting of cellulose/NMMO solution at 70 ℃ was analogous to that of thermoplastics by the process of melting and solidification to produce cellulose/NMMO objects in the solid form. However, 3D bioprinting of cellulose/NMMO solution at a higher temperature than 70 ℃ produced cellulose/NMMO objects in the gel form. Cellulose was regenerated by water; thereafter, freeze-drying treatment maintained the 3D bioprinted structures…
Novel antimicrobial 3D-printed alginate/bacterial-cellulose hydrogels with in situ-synthesized copper nanostructures were developed having improved printability. Prior to 3D printing, two methods were tested for the development of the alginate hydrogels: (a) ionic cross-linking with calcium ions followed by ion exchange with copper ions (method A) and (b) ionic cross-linking with copper ions (method B). A solution containing sodium borohydride, used as a reducing agent, was subsequently added to the hydrogels, producing in situ clusters of copper nanoparticles embedded in the alginate hydrogel matrix. The method used and concentrations of copper and the reducing agent were found to affect the stability…