With good cytocompatibility, bioactivity, and slow degradation rate, hydroxyapatite (HAP) may remedy drawbacks of hyaluronan (HA) as soft tissue filler. Here, we prepared HA-HAP composite hydrogels by one-step reaction method, investigated various processing parameters on their physicochemical properties, and evaluated their biological performance. As-prepared HA-HAP composite hydrogels contained 1.5%-3.0% HA and 2.38%-15.8% HAP with good sterilization stability. Swelling-ratio and mechanical performance of the composite hydrogels could be adjusted by controlling HAP content and crosslinking reagent. The equilibrium swelling ratio achieved over 90% only after 1 h swell, and the swelling properties fitted well with 1^st-order exponential decay equations. By 1500 U/mL HAase solutions, the composites degraded 95% after only 2 min and dispersed rapidly, showing good enzymatic degradability. HAP was demonstrated not only endowing the composite hydrogels with better plasticity for facial soft tissue filler and contour modification, but also providing good microenvironment for attachment and proliferation of fibroblasts. Therefore, the as-prepared HA-HAP composite could be used as a long-acting filler for remodeling extracellular matrix, and thus potentially applied in cosmetic medicine.

Copper-containing biomaterials have excellent inhibitory effect on bacteria growth by releasing copper ions at high concentration, which may have cytotoxicity at the same time. Although low concentration of copper ions has good cytocompatibility, the antibacterial activity is unsatisfactory. Therefore, it is of great significance to develop copper- containing biomaterials, which have excellent antibacterial property and good cytocompatibility. In this study, on considering the antagonistic effect between copper and molybdenum, molybdenum doped cuprorivaite (Mo-Cup) was synthesized by Sol-Gel method and its antibacterial properties and cell compatibility were evaluated by bacterial plate experiment and cell activity assay. The results showed that copper ions with high concentration (above 8.87 μg∙mL ^-1) released from Mo-Cup had a good inhibitory effect on Staphylococcus aureus. In addition, because the antagonistic effect between copper and molybdenum ions released from Mo-Cup can reduce the cytotoxicity of high concentration of copper ions, the survival rate of umbilical vein endothelial cells (HUVECs) was as high as 90% in the extracts of Mo-Cup at a high Cu ion concentration (9.65 μg∙mL ^-1). Therefore, molybdenum doping can be considered as an effective approach to reduce the cytotoxicity of copper-containing biomaterials for the development of low-toxic antibacterial biomaterials.

Bacteria-related diseases, environmental pollution and other issues have attracted enough attention. Meanwhile, with the use of antibiotics, bacteria evolved strong drug resistance forcing people to develop new antibacterial agents urgently. Natural enzymes such as lysozyme and myeloperoxidase have significant antibacterial ability. However, natural enzymes own limitations such as short shelf life and high production costs. Besides, they are difficult in applying to large-scale production. Therefore, people are seeking alternatives to natural enzymes. Nanozymes are a new generation of artificial enzymes which have unique physical and chemical properties of nanomaterials and enzyme-like catalytic activity. Because of structural stability and low production cost, they are widely explored. This article reviews the antimicrobial mechanism and the recent progress of nanozymes in antibacterial research, and, finally, gives some prospects for future research.

To prevent potassium diformate (KDF) from decomposing too quickly in an acidic environment, adjust the acidity and alkalinity of the gastrointestinal tract of the piglets and the colony balance, and realize the targeted release of KDF antibacterial, in this study, a kind of hydrogel microspheres were prepared by biodegradable chitosan (CS), carboxymethyl cellulose (CMC), and inorganic rigid material P-type molecular sieve (Zeolite P). Then the antibacterial drug potassium diformate was loaded so as to be controlled to release from this hydrogel microsphere. The results show that -NH₂ in CS and -COOH in CMC form a stable polyelectrolyte complex through ion interaction. Swelling rate test indicates that the CS/CMC/Zeolite P hydrogel microspheres display high pH-sensitivity. The addition of Zeolite P allows the hydrogel microspheres to maintain their original morphology at pH1.2 without being degraded or broken. The effective sustained-release KDF in pH7.4 phosphate buffer solution exhibits better sustained-release performance than that in pH1.2. When the concentration of CS/CMC/Zeolite P/KDF antimicrobial microspheres is 96 mg/mL, the maximum bacteriostatic rate of Escherichia coli is 83%, which effectively improves the utilization rate of KDF.

Titanium and its alloys have been wildly used as bone implants. However, it is still facing a severer issue: implant related infections due to the lack of antibacterial ability. Copper (Cu) has good antibacterial ability and can be used to improve the anti-infection capability of titanium. In this study, three kinds of Ti samples with different contents of Cu in the modified layer were prepared by plasma immersion ion implantation (PIII) technology, and their responses to bacteria and cells were explored in vitro. The results showed that the sample with low Cu content at the surface could promote the proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) and human umbilical vein endothelial cells (HUVECs) but not inhibit the proliferation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). As the implantation time extends, antibacterial ability of the samples with high Cu content at the surface was significantly enhanced, and no obvious cytotoxicity was observed. Therefore, it is possible to acquire a balance between antibacterial ability and biocompatibility of Ti by controlling the contents of Cu in the modified layer.