Jianliang Zhou

Biofunctionalization of titanium with bacitracin immobilization shows potential for anti-bacteria, osteogenesis and reduction of macrophage inflammation

Titanium has been widely used in the orthopedic and dental fields, however, the inert nature of Ti makes it unsuitable for application in promoting bone cell growth，osteogenic differentiation and antibacterial ability. The aims of the current study were to investigate the antimicrobial activity and biofunction of the polypeptide antibiotic bacitracin, and obtain a multi-biofunctional titanium implant by covalently-immobilizing titanium with the bacitracin. The results showed that the bacitracin possessed low minimum inhibitory concentration (MIC) to both Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA), with the non-cytotoxicity concentration up to 500μg/mL to human bone marrow mesenchymal stem cells (hBMSCs), furthermore, the bacitracin could improve the osteogenic differentiation of hBMSCs. The results of Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) indicated that bacitracin had been covalently immobilized on the surface of titanium. Immobilized bacitracin could improve the hydrophilic of immobilized titanium. The results of antimicrobial assay demonstrated that the covalently-immobilized bacitracin also had excellent antimicrobial property, and the bacitracin immobilized titanium could inhibit bacterial adhesion and colonization. The results of cell biology experiments proved that the bacitracin immobilized titanium could improve hBMSCs adhesion, proliferation and osteogenic differentiation. We also found that the macrophages were difficult to spread or activate on the surface of bacitracin immobilized titanium, and the secretion of inflammatory factors had been inhibited. In conclusion, the novel bacitracin immobilized titanium has multi-biofunctions including outstanding antibacterial properties, excellent cell biology performance, and restraining inflammation, which has exciting application prospect.

Covalent immobilization of KR-12 peptide onto a titanium surface for decreasing infection and promoting osteogenic differentiation

Infection and poor bone-implant integration are the two main reasons for titanium (Ti) implant failure. Here, we investigated the feasibility of functionalizing Ti with the antimicrobial peptide, KR-12, derived from the human cationic antimicrobial peptide. The minimal inhibitory concentration and cell viability effects of KR-12 were investigated prior to immobilization on the Ti surface. The results showed that KR-12 possessed a wide anti-bacterial spectrum with no cytotoxicity to human bone marrow mesenchymal stem cells (hBMSCs). Successful covalent immobilization of KR-12 onto an amine-functionalized Ti (Ti-KR-12) surface was characterized by X-ray photoelectron spectroscopy. Gram-positive bacteria, Staphylococcus epidermidis and methicillin resistant Staphylococcus epidermidis were employed for antibacterial characterization. Ti-KR-12 substrates could significantly inhibit adhesion and colonization of common pathogenic bacteria and the drug resistance of pathogenic bacteria. The results of the CCK-8 assay, confocal laser scanning microscopy, and scanning electron microscopy showed that KR-12 covalently immobilized on Ti improved adhesion and proliferation of hBMSCs. The osteogenic differentiation of hBMSCs on samples was investigated by alkaline phosphatase staining, sirius red staining, alizarin red staining, and real-time PCR. The staining and real-time PCR results demonstrated that hBMSCs grown on Ti-KR-12 surfaces for 10 and 14 days under conditions inducing osteogenic differentiation displayed significantly higher alkaline phosphatase activity, larger extracellular matrix calcium deposition area, and higher expression of alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 mRNA than bare Ti. Our results demonstrated the KR-12 peptide was suitable for improving the biological properties of bioinert titanium. KR-12 showed antibacterial activity and the capability to promote cell proliferation and Ti-KR-12 surfaces significantly decreased bacteria adhesion, whilst promoting the osteogenic differentiation of hBMSCs.

Synthesis and magnetic properties of MNb2O6 (M = Fe, Co, Ni) nanoparticles

Considerable efforts have been exerted on the controllable synthesis of columbite niobate ceramics due to their fascinating properties and applications. Especially, it is still a great challenge to fabricate nanostructures of the niobate series. In this research, FeNb2O6, CoNb2O6 and NiNb2O6 nanoparticles have been successfully prepared via a facile hydrothermal route followed by heat treatment. X-ray powder diffraction patterns show that all the products have the typical orthorhombic columbite structure. The electron microscopy analyses reveal that the obtained nanoparticles have diameters of 50–100 nm. The magnetic property results demonstrate that the magnetically ordered state is hard to observe down to 1.8 K for the FeNb2O6 sample, while the magnetic transition temperatures of TN = 3 K and TN = 6 K can be obtained for CoNb2O6 and NiNb2O6 samples, respectively. A weak ferromagnetic moment can be detected below 5 K for both CoNb2O6 and NiNb2O6 samples. Furthermore, the NiNb2O6 sample even exhibits a metamagnetic transition at 1.8 K due to the spin flipping of the ferromagnetic chains.

Immobilizing bacitracin on titanium for prophylaxis of infections and for improving osteoinductivity: An in vivo study.

Bacitracin immobilized on the titanium (Ti) surface significantly improves anti-bacterial activity and biocompatibility in vitro. In the current study, we investigated the biologic performance (bactericidal effect and bone-implant integration) of bacitracin-modified Ti in vivo. A rat osteomyelitis model with femoral medullary cavity placement of Ti rods was employed to analyze the prophylactic effect of bacitracin-modified Ti (Ti-BC). Thirty-six female Sprague Dawley (SD) rats were used to establish the Ti implant-associated infection. The Ti and Ti-BC rods were incubated with and without Staphylococcus aureus to mimic the contaminated Ti rod and were implanted into the medullary cavity of the left femur, and sterile Ti rods were used as the blank control. After 3 weeks, the bone pathology was evaluated using X-ray and micro-computed tomography (micro-CT) analysis. For the investigation of the Ti-BC implant osseointegration in vivo, fifteen SD rats were divided into three groups (N=5), namely Ti, Ti-dopamine immobilized (Ti-DOPA), and Ti-BC. Ti rods were implanted into the left femoral cavity and micro-CT and histological evaluation was conducted after 12 weeks. The in vivo study indicated that Ti-immobilized bacitracin owned the prophylaxis potential for the infection associated with the Ti implants and allowed for the osseointegration. Thus, the multiple biofunctionalized Ti implants could be realized via immobilization of bacitracin, making them promising candidates for preventing the Ti implant-associated infections while retaining the osseointegration effects.

Covalent Immobilization of Enoxacin onto Titanium Implant Surfaces for Inhibiting Multiple Bacterial Species Infection and In Vivo Methicillin-Resistant Staphylococcus aureus Infection Prophylaxis

ABSTRACT Infection is one of the most important causes of titanium implant failure in vivo. A developing prophylactic method involves the immobilization of antibiotics, especially vancomycin, onto the surface of the titanium implant. However, these methods have a limited effect in curbing multiple bacterial infections due to antibiotic specificity. In the current study, enoxacin was covalently bound to an amine-functionalized Ti surface by use of a polyethylene glycol (PEG) spacer, and the bactericidal effectiveness was investigated in vitro and in vivo. The titanium surface was amine functionalized with 3-aminopropyltriethoxysilane (APTES), through which PEG spacer molecules were covalently immobilized onto the titanium, and then the enoxacin was covalently bound to the PEG, which was confirmed by X-ray photoelectron spectrometry (XPS). A spread plate assay, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM) were used to characterize the antimicrobial activity. For the in vivo study, Ti implants were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and implanted into the femoral medullary cavity of rats. The degree of infection was assessed by radiography, micro-computed tomography, and determination of the counts of adherent bacteria 3 weeks after surgery. Our data demonstrate that the enoxacin-modified PEGylated Ti surface effectively prevented bacterial colonization without compromising cell viability, adhesion, or proliferation in vitro. Furthermore, it prevented MRSA infection of the Ti implants in vivo. Taken together, our results demonstrate that the use of enoxacin-modified Ti is a potential approach to the alleviation of infections of Ti implants by multiple bacterial species.

A novel approach to prepare a tissue engineering decellularized valve scaffold with poly(ethylene glycol)–poly(ε-caprolactone)

The objective of this study was to explore the feasibility of preparing a decellularized valve scaffold with methoxy poly(ethylene glycol)–poly(e-caprolactone) (MPEG–PCL). This is the first report of applying MPEG–PCL to decellularize porcine aortic valves (PAVs). We evaluated its decellularization activity versus two commonly used agents (Triton X-100 and sodium deoxycholate (SD)) in terms of histological morphology, amount of valve-related components, biocompatibility and mechanical properties. The results revealed that 1% MPEG–PCL fully decellularized the valve cells, and the valve fiber structure remained intact. Compared to untreated native valves, the amount of residual DNA in the decellularization groups treated with 1% MPEG–PCL, Triton X-100 and SD were significantly reduced. The water content and collagen content in none of the decellularization groups were significantly different from the native valves. However, the elastin content in the valves of all the decellularization groups was significantly lower than in the native valves. In all the decellularization groups, some degree of platelet adhesion was observed, but the hemolysis rates of all groups were significantly smaller versus the native group. Cytotoxicity testing showed that MPEG–PCL was non-cytotoxic. For every decellularization group, the mechanical properties of the valve scaffolds along circumferential and radial directions were not significantly different from that of the valves. Our study indicates that MPEG–PCL can be used to prepare decellularized PAV. MPEG–PCL is non-cytotoxic and can completely remove cells from the valve while maintaining an intact extracellular matrix ultrastructure. We provide a novel decellularization method for the construction of a tissue engineered heart valve.

Knockdown of PSMC3IP suppresses the proliferation and xenografted tumorigenesis of hepatocellular carcinoma cell: DING et al.

Hepatocellular carcinoma (HCC) is the fifth most frequent malignancy and the second leading cause of cancer‐related death worldwide. Proteasome 26S subunit ATPase 3 interacting protein (PSMC3IP) is an oncogene in breast cancer, while its role in HCC remains unclear. Here, we found that PSMC3IP was critical for the cell proliferation and tumorigenic capacity of HCC cells. Upregulation of PSMC3IP was observed in HCC specimens, and high PSMC3IP expression predicted poor overall survival of HCC patients. In vitro, knockdown of PSMC3IP blunted the proliferation and colony formation of BEL‐7404 and SMMC‐7721 cells. Likewise, PSMC3IP silencing suppressed the xenografted tumor development of BEL‐7404 cells. Mechanistically, apoptosis was enhanced after PSMC3IP knockdown in both BEL‐7404 and SMMC‐7721 cells. At the molecular level, TP53 and GNG4 were upregulated and eukaryotic translation initiation factor 4E (EIF4E) and insulin like growth factor 1 receptor (IGF1R) were downregulated in shPSMC3IP compared with shCtrl BEL‐7404 cells. Therefore, targeting PSMC3IP maybe a promising strategy for HCC.