Chronic wounds are greatly health threatening owing to the increasing morbidity, and bacterial biofilm is a major cause of chronic wounds. The critical for bacterial biofilm eradication is overcome the barrier of extracellular polymeric substances (EPS) produced by the bacteria, and promote the diffusion of drugs within the biofilm. In this article, composite microneedles (MNs) of chitosan and zinc nitrate (CS-Zn[II] MNs) were investigated to eradicate bacterial biofilm. The CS-Zn(II) MNs combined the structure characteristic of MNs with the antibacterial properties of CS and Zn 2+ . The MNs can pierce the EPS due to the needle-like structure, and can transport directly the CS and Zn 2+ into the bacterial biofilm. The needle-like structure of MNs also increased the contact area between drug carrier and bacterial biofilm nearly 14–23% comparing with membrane without needle-like structure, and facilitated the diffusion of drugs. What is more, the synergistic effect of CS and Zn 2+ make the CS-Zn(II) MNs obtain excellent antibiofilm properties. Counting the colony forming units and bacterial live/dead staining tests confirmed the fascinating antibacterial abilities (up to 100% inhibition) and biofilm eradication properties, respectively, of the CS-Zn(II) MNs. The inhibition zone test shown that the antibiofilm effect of MNs was superior to membrane and the antibiofilm effect of MNs was become increasingly obvious along with the increase of the treatment time. Besides, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays proved that the CS-Zn(II) MNs possess brilliant cytocompatibility. These results indicate that the CS-Zn(II) MNs are promising method for bacterial biofilm eradication.
Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO 2 -P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO 3 ) 2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO 2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956–1126 m 2 g −1 ), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44–5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99–3.32 at%), exhibiting good accessibility and reinforced interaction with SO 2 . Consequently, the DAP-NHPC-T show high SO 2 capacity (14.7 mmol g −1 , 25 °C and 1.0 bar) and SO 2 /CO 2 /N 2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO 2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.
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