Zinc hybrid polyester barrier membrane accelerates guided tissue regeneration.

Barrier membranes play a pivotal role in the success of guided periodontal tissue regeneration. The biodegradable barriers predominantly used in clinical practice often lack sufficient barrier strength, antibacterial properties, and bioactivity, frequently leading to suboptimal regeneration outcomes. Although with advantages in mechanical strength, biodegradability and plasticity, bioinert aliphatic polyesters as barrier materials are usually polymerized via toxic catalysts, hard to be functionalized and lack of antibacterial properties. To address these challenges, we propose a new concept that controlled release of bioactive substance on the whole degradation course can give a bioinert aliphatic polyester bioactivity. Thus, a Zn-based catalytic system for polycondensation of dicarboxylic acids and diols is created to prepare zinc covalent hybrid polyester (PBS/ZnO). The atomically-dispersed Zn2+ ions entering main chain of polyester molecules endow PBS/ZnO barrier with antibacterial properties, barrier strength, excellent biocompatibility and histocompatibility. Further studies reveal that relying on long-term controlled release of Zn2+ ions, the PBS/ZnO membrane greatly expedites osteogenetic effect in guided tissue regeneration (GTR) by enhancing the mitochondrial function of macrophages to induce M2 polarization. These findings show a novel preparation strategy of bioactive polyester biomaterials based on long term controlled release of bioactive substance that integrates catalysis, material structures and function customization.

Click-based injectable bioactive PEG-hydrogels guide rapid craniomaxillofacial bone regeneration by the spatiotemporal delivery of rhBMP-2.

Craniomaxillofacial bone defects result in physical and psychological dual injuries making the promotion or acceleration of bone regeneration imperative. In this work, a fully biodegradable hydrogel is facilely prepared via thiol-ene "click" reactions under human physiological conditions using multifunctional poly(ethylene glycol) (PEG) derivatives as precursors. This hydrogel shows excellent biological compatibility, enough mechanical strength, a low swelling rate and an appropriate degradation rate. Rat bone marrow mesenchymal stem cells (rBMSCs) can survive and proliferate on/in the PEG hydrogel and differentiate into osteogenic cells. The PEG hydrogel can also effectively load rhBMP-2 through the above "click" reaction. Under the physical barrier of the chemically crosslinked hydrogel network, the spatiotemporal release of rhBMP-2 effectively promotes the proliferation and osteogenic differentiation of rBMSCs at a loading concentration of 1 µg ml-1. Finally, based on a rat calvarial critical-size defect model, the rhBMP-2 immobilized hydrogel loaded with rBMSCs basically accomplishes the repair and regeneration within 4 weeks featured by remarkably enhanced osteogenesis and angiogenesis. The click-based injectable bioactive PEG hydrogel developed in the present study is a new type of bone substitute with great expectations in future clinical applications.

Dialdehyde-ß-cyclodextrin-crosslinked carboxymethyl chitosan hydrogel for drug release.

A simple method was proposed for preparing the dialdehyde-ß-cyclodextrin (DA-ß-CD) cross-linked carboxymethyl chitosan (CMCS) hydrogels for drug delivery. DA-ß-CD was yielded from the sodium periodate oxidation of ß-CD. Phenolphthalein (PhP) was adopted as a model drug to study the drug loading and releasing properties of the obtained hydrogels. The results show that the ability of the hydrogel to load drug is affected by the aldehyde content of DA-ß-CD. The inclusion constant of DA-ß-CD toward PhP is lower than that of the original ß-CD and decreased with the rising of the aldehyde content. An increased cross-linking degree between DA-ß-CD and CMCS slows the PhP release to some extent. In comparison with glyoxal/CMCS, DA-ß-CD/CMCS presents better PhP release properties. Only 19.2 % of PhP loaded in glyoxal/CMCS was released within 24 h. Half of PhP loaded in DA-ß-CD/CMCS was released in 2 h and about 90 % was released within 12 h.