Antibacterial Vancomycin@ZIF-8 Loaded PVA Nanofiber Membrane for Infected Bone Repair.

Bone substitutes with strong antibacterial properties and bone regeneration effects have an inherent potential in the treatment of severe bone tissue infections, such as osteomyelitis. In this study, vancomycin (Van) was loaded into zeolitic imidazolate framework-8 (ZIF-8) to prepare composite particles, which is abbreviated as V@Z. As a pH-responsive particle, ZIF-8 can be cleaved in the weak acid environment caused by bacterial infection to realize the effective release of drugs. Then, V@Z was loaded into polyvinyl alcohol (PVA) fiber by electrospinning to prepare PVA/V@Z composite bone filler. The drug-loading rate of V@Z was about 6.735%. The membranes exhibited super hydrophilicity, water absorption and pH-controlled Van release behavior. The properties of anti E. coli and S. aureus were studied under the pH conditions of normal physiological tissues and infected tissues (pH 7.4 and pH 6.5, respectively). It was found that the material had good surface antibacterial adhesion and antibacterial property. The PVA/V@Z membrane had the more prominent bacteria-killing effect compared with the same amount of single antibacterial agent containing membrane such as ZIF-8 or Van loaded PVA, and the antibacterial rate was up to 99%. The electrospun membrane had good biocompatibility and can promote MC3T3-E1 cell spreading on it.

Paclitaxel-loaded lignin particle encapsulated into electrospun PVA/PVP composite nanofiber for effective cervical cancer cell inhibition.

Electrospun composite nanofibrous scaffolds have been regarded as a potential carrier for local drug delivery to prevent tumor recurrence. Herein, a model drug (paclitaxel) was creatively loaded into lignin nanoparticles (PLNPs) and then encapsulated into the polymer of poly (vinyl alcohol)/polyvinyl pyrrolidone which has been fabricated into a composite nanofibrous membrane (PVA/PVP-PLNPs) for use as a drug carrier using the electrospinning technique. The fabricated PVA/PVP-PLNPs membranes exhibited good particle distribution, mechanical properties, thermal stability and biocompatibility. In vitro experiments showed that combining lignin nanoparticles by electrospinning not only improved the drug release profile, but also enhanced the hydrophilicity of nanofibrous membranes which was beneficial to cell adhesion and proliferation. Cellular experiments demonstrated that PVA/PVP-2%PLNPs membrane showed good cell inhibition ability, and the cell survival rate was only 21% at day 7. It indicates that the as-prepared PVA/PVP-PLNPs composite nanofibers are promising candidates for local anticancer therapy.

Progress of laser surface treatment on magnesium alloy.

Magnesium (Mg) metals have been widely used in various fields as one of the most promising lightweight structural materials. However, the low corrosion resistance and poor mechanical properties restrict its applications. Surface treatments are common approach to enhance the mechanical strength and corrosion resistance of Mg metals. Among them, laser surface treatment generates novel tissues and structures in situ on the sample surface, thereby improving properties of mechanical strength and corrosion resistance. We briefly describe the changes in surface organization that arise after laser treatment of Mg surfaces, as well as the creation of structures such as streaks, particles, holes, craters, etc., and provide an overview of the reasons for the alterations. The effect of laser processing on wettability, hardness, friction wear, degradation, biocompatibility and mechanical properties were reviewed. At last, the limitations and development trend of laser treatment on Mg metals research were further pointed out.

Improve endothelialization of metallic cardiovascular stent via femtosecond laser induced micro/nanostructure dependent cells proliferation and drug delivery control.

Regarding restenosis occurrence risk after metallic stent deployment in artery, stents with vascular smooth muscle cells antiproliferative agents sustained released from poly(lactic-co-glycolic acid) (PLGA) coating and endothelial cells proliferation favored surface textures were both attempted for endothelialization enhancement. In order to explore the interaction between the surface texture and performance of drug loaded PLGA coating, femtosecond laser surface treatment was used to change the surface characteristics of 316L stainless steel. Two different surface patterns in form of stripe (FSL100) and isolated island-like structure (FSL800) were firstly generated by femtosecond laser processing with 100 and 800 mW energy, then Rapamycin loaded PLGA coating was further deposited to polished and femtosecond laser processed 316L surfaces via a dip-coating method. The subsequent drug loading capacity and release profile studies confirmed the roles of surface texture. Morphological transition characteristics of the PLGA coating on the FLS100 sample indicate that the coating has integrity during degradation compared to the polished one. Finally, rapamycin eluting FLS100 stent was deployed to iliac arteries of New Zealand White rabbits with vascular plaques to demonstrate its endothelialization potential and resistance to restenosis.

Porous thermosensitive coating with water-locking ability for enhanced osteogenic and antibacterial abilities.

Preferable antibacterial property and osteogenesis are the permanent pursuit for metallic implants. However, it is difficult to satisfy both the properties. In fact, implants may be contaminated with bacteria during storage and surgery, leading to inflammation. Therefore, the antibacterial property of biomaterial surfaces is required not only in the human environment but also at room temperature. In this study, porous structures loaded with a thermosensitive poly (N-isopropylacrylamide) (PNIPAM) hydrogel on a nitinol (NiTi) substrate were constructed. When the temperature is 25 â€‹°C, almost all bacteria cannot adhere to the sample surface due to the abundant hydration layer of the PNIPAM hydrogel. Meanwhile, when the temperature is 37 â€‹°C, the structure of the PNIPAM hydrogel collapses and the hydration layer disappears due to the temperature change. However, the porous structures lock water in the pores, which results in a high-hydration-rate sample surface. This surface has few bacterial adhesion sites; nevertheless, the adhesion of larger cells to the surface is not impeded by the porous structure. In addition, the PNIPAM hydrogel is soft and biocompatible, so the sample can have better cell adhesion and proliferation than a bare NiTi alloy. Based on these results, it can be concluded that the porous NiTi sample loaded with the thermosensitive PNIPAM hydrogel has the antibacterial property before implantation and the dual function of inhibiting bacterial adhesion and promoting cell adhesion and proliferation after implantation, which shows promising applications in the biomedical field such as orthopedic implantation.

MXene Quantum Dot/Zeolitic Imidazolate Framework Nanocarriers for Dual Stimulus Triggered Tumor Chemo-Phototherapy.

It is critical to construct stimuli-responsive multifunctional nanoparticles for the drug delivery system for cancer treatment. Zeolitic imidazolate framework-8 (ZIF-8) has a large specific surface area and decomposes quickly under acidic conditions, which presents an excellent potential in pH-sensitive drug carriers. However, the mere chemotherapeutic drug loaded into ZIF-8 is a monotherapy and may restrict the therapeutic efficacy of malignancies. In this work, an effective nanoparticle-based delivery platform is established to simultaneously encapsulate doxorubicin (DOX) and MXene quantum dot (MQD) in ZIF-8 nanoparticles (MQD@ZIF-8/DOX). Under near-infrared (NIR) laser (808 nm) and UV light (365 nm) irradiation, MQD@ZIF-8 demonstrates a high photothermal conversion efficiency and reactive oxygen species (ROS) production, which shows excellent photothermal therapy and photodynamic therapy effects. Furthermore, the release of DOX-loaded into MQD@ZIF-8 nanoparticles is significantly increased under NIR laser irradiation and at pH 5.6, indicating that acidic conditions and NIR laser irradiation can be effectively combined to stimulate the drug release. The cellular experiments show that MQD@ZIF-8/DOX has an obvious killing effect on HeLa cells and achieves the combined anti-tumor effect of chemotherapy and phototherapy.

Femtosecond laser-induced nanoporous layer for enhanced osteogenesis of titanium implants.

The osteogenic activity of medical metal can be improved by lowering its surface stiffness and elastic modulus. However, it is very difficult to directly reduce the elastic modulus of medical metal surfaces. In this paper, with selected parameters, the titanium surface was treated via femtosecond laser irradiation. Micro indentation revealed that the femtosecond laser ablation can effectively reduce the surface Young's modulus and Vickers hardness of titanium. Besides, In order to explain the mechanical properties of degradation of titanium surface, Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used to simulate the process of laser ablation process of titanium surface, and it was found that after the ablation of titanium surface, voids were produced in the subsurface layer. The simulation showed that the voids are formed by the cavitation of metastable liquid induced by high tensile stress and high temperature during femtosecond laser irradiation. Subsurface voids with a thickness of about 40 nm were observed under the oxide layer in the experiment. Cell experiments showed that the surface with low Young's modulus was more conducive to cell proliferation and osteogenic differentiation.