Zhi-Cai Xing

In Vitro Assessment of Antibacterial Activity and Cytocompatibility of Silver-Containing PHBV Nanofibrous Scaffolds for Tissue Engineering

Infections with bacteria have become a serious problem in joint arthroplasty. This study reports about in vitro antibacterial activity and in vitro cell compatibility of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers loaded with metallic silver particles of a size of 5-13 nm. In vitro antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae was studied by microplate proliferation tests. The adhesion, viability, and proliferation properties of fibroblasts (NIH 3T3) and differentiation of osteoblasts (MC3T3-E1) were done to study in vitro cell compatibility of the scaffolds. As the results, only silver-containing PHBV nanofibrous scaffolds showed a high antibacterial activity and an inhibitory effect on the growth of both Staphylococcus aureus and Klebsiella pneumoniae bacteria. The nanofibrous scaffolds having silver nanoparticles <1.0% were free of in vitro cytotoxicity. To sum up, the PHBV nanofibrous scaffolds having nanoparticles <1.0 wt % showed not only good antibacterial activity but also good in vitro cell compatibility. It is considered that the PHBV nanofibrous scaffolds with silver nanoparticles <1.0 wt % have a potential to be used in joint arthroplasty.

Immobilization of biomolecules on the surface of inorganic nanoparticles for biomedical applications

Abstract Various inorganic nanoparticles have been used for drug delivery, magnetic resonance and fluorescence imaging, and cell targeting owing to their unique properties, such as large surface area and efficient contrasting effect. In this review, we focus on the surface functionalization of inorganic nanoparticles via immobilization of biomolecules and the corresponding surface interactions with biocomponents. Applications of surface-modified inorganic nanoparticles in biomedical fields are also outlined.

Fabrication of Biodegradable Polyester Nanocomposites by Electrospinning for Tissue Engineering

Recently, nanocomposites have emerged as an efficient strategy to upgrade the structural and functional properties of synthetic polymers. Polyesters have attracted wide attention because of their biodegradability and biocompatibility. A logic consequence has been the introduction of natural extracellular matrix (ECM) molecules, organic or inorganic nanostructures to biodegradable polymers to produce nanocomposites with enhanced properties. Consequently, the improvement of the interfacial adhesion between biodegradable polymers and natural ECM molecules or nanostructures has become the key technique in the fabrication of nanocomposites. Electrospinning has been employed extensively in the design and development of tissue engineering scaffolds to generate nanofibrous substrates of synthetic biodegradable polymers and to simulate the cellular microenvironment. In this paper, several types of biodegradable polyester nanocomposites were prepared by electrospinning, with the aim of being used as tissue engineering scaffolds. The combination of biodegradable nanofibrous polymers and natural ECM molecules or nanostructures opens new paradigms for tissue engineering applications.

Enhanced Osteoblast Responses to Poly(Methyl Methacrylate)/Hydroxyapatite Electrospun Nanocomposites for Bone Tissue Engineering

Abstract Hydroxyapatite (HA)-containing polymers have been proposed for improving the biological properties of bone cements. Poly(methyl methacrylate) (PMMA) has long been used to secure orthopedic implants to skeletal bones. The aim of this study was to determine whether the incorporation of HA nanoparticles into the PMMA nanofibrous scaffolds enhances the biological functions of osteoblasts. The number of osteoblasts adhered and proliferated on the PMMA/HA nanofibrous scaffolds was significantly larger than that on the PMMA alone. The cytoskeletal organization and alkaline phosphatase (ALP) activity of the osteoblasts on the PMMA/HA nanofibrous scaffolds were clearly higher than that on the PMMA control. The amount of calcium ions released from 20 wt% HA-containing PMMA nanofibrous scaffolds (PMMA/HA20) was much higher than that released from 10 wt% HA-containing PMMA nanofibrous scaffolds (PMMA/HA10) (HA, 10 wt%). These findings suggested that osteoblast differentiation was accelerated by the incorporation of HA into the PMMA nanofibrous scaffolds. Therefore, the incorporation of HA into the PMMA nanofibrous scaffolds could be a useful method. This can be used for providing PMMA scaffolds with enhanced osteogenic properties.

Immobilization of pamidronic acids on the nanotube surface of titanium discs and their interaction with bone cells

Self-assembled layers of vertically aligned titanium nanotubes were fabricated on a Ti disc by anodization. Pamidronic acids (PDAs) were then immobilized on the nanotube surface to improve osseointegration. Wide-angle X-ray diffraction, X-ray photoelectron microscopy, and scanning electron microscopy were employed to characterize the structure and morphology of the PDA-immobilized TiO2 nanotubes. The in vitro behavior of osteoblast and osteoclast cells cultured on an unmodified and surface-modified Ti disc was examined in terms of cell adhesion, proliferation, and differentiation. Osteoblast adhesion, proliferation, and differentiation were improved substantially by the topography of the TiO2 nanotubes, producing an interlocked cell structure. PDA immobilized on the TiO2 nanotube surface suppressed the viability of the osteoclasts and reduced their bone resorption activity.

Novel wound dressing based on nanofibrous PHBV–keratin mats

Keratin is an important protein used for wound healing and tissue recovery. In this study, keratin was first extracted from raw materials and chemically modified to obtain stable keratin (m‐keratin). The raw and m‐keratin were examined by Raman spectroscopy. The molecular weight of the m‐keratin was analysed by SDS–PAGE. The m‐keratin was then blended with poly(hydroxybutylate‐co‐hydroxyvalerate) (PHBV) and electrospun to afford nanofibrous mats. These mats were characterized by field emission scanning electron microscopy (FE‐SEM), electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). From the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) data, it was found that introduction of keratin enhanced cell proliferation. From wound‐healing test and histological examination results, it was shown that the composite mats accelerated wound recovery remarkably as compared to the PHBV control. It was concluded that PHBV–keratin may be a good candidate as a wound dressing. Copyright

Fabrication and characterization of collagen-immobilized porous PHBV/HA nanocomposite scaffolds for bone tissue engineering

The porous composite scaffolds (PHBV/HA) consisting of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) were fabricated using a hot-press machine and salt-leaching. Collagen (type I) was then immobilized on the surface of the porous PHBV/HA composite scaffolds to improve tissue compatibility. The structure and morphology of the collagen-immobilized composite scaffolds (PHBV/HA/Col) were investigated using a scanning electron microscope (SEM), Fourier transform infrared (FTIR), and electron spectroscopy for chemical analysis (ESCA). The potential of the porous PHBV/HA/Col composite scaffolds for use as a bone scaffold was assessed by an experiment with osteoblast cells (MC3T3-E1) in terms of cell adhesion, proliferation, and differentiation. The results showed that the PHBV/HA/Col composite scaffolds possess better cell adhesion and significantly higher proliferation and differentiation than the PHBV/HA composite scaffolds and the PHBV scaffolds. These results suggest that the PHBV/HA/Col composite scaffolds have a high potential for use in the field of bone regeneration and tissue engineering.

Reduced cytotoxicity of insulin-immobilized CdS quantum dots using PEG as a spacer

Cytotoxicity is a severe problem for cadmium sulfide nanoparticles (CSNPs) in biological systems. In this study, mercaptoacetic acid-coated CSNPs, typical semiconductor Q-dots, were synthesized in aqueous medium by the arrested precipitation method. Then, amino-terminated polyethylene glycol (PEG) was conjugated to the surface of CSNPs (PCSNPs) in order to introduce amino groups to the surface. Finally, insulin was immobilized on the surface of PCSNPs (ICSNPs) to reduce cytotoxicity as well as to enhance cell compatibility. The presence of insulin on the surface of ICSNPs was confirmed by observing infrared absorptions of amide I and II. The mean diameter of ICSNPs as determined by dynamic light scattering was about 38 nm. Human fibroblasts were cultured in the absence and presence of cadmium sulfide nanoparticles to evaluate cytotoxicity and cell compatibility. The results showed that the cytotoxicity of insulin-immobilized cadmium sulfide nanoparticles was significantly suppressed by usage of PEG as a spacer. In addition, cell proliferation was highly facilitated by the addition of ICSNPs. The ICSNPs used in this study will be potentials to be used in bio-imaging applications.

In vitro assessment of antibacterial activity and cytocompatibility of quercetin-containing PLGA nanofibrous scaffolds for tissue engineering

Flavonoids, such as quercetin, have been reported to exhibit a wide range of biological activities related to their antioxidant capacity. The aim of this study was to investigate the protective effect of quercetin on cell adhesion, and the viability and proliferation of KB epithelial cells. Quercetin- (1, 5wt%)-containing poly (l-lactide-co-glycolide) (PLGA) nanofibrous scaffolds (PLGA/Q 1, PLGA/Q 5) were prepared by electrospinning technique and their antibacterial properties were examined. Two types of bacteria strains, Staphylococcus aureus (SA) and Klebsiella pneumoniae (KP), were used to evaluate the antibacterial properties of the scaffolds. The results showed that the quercetin-containing PLGA nanofibrous scaffolds exhibited significant antibacterial effects against the two bacterial strains. KB epithelial cells were also used to evaluate the cytocompatibility of the scaffolds. From the results, it was found that the PLGA nanofibrous scaffolds with 1wt% of quercetin had good cell compatibility. It is considered that the PLGA nanofibrous scaffolds with 1wt% quercetin have potential to be used in tissue engineering.

Immobilization of lactobionic acid on the surface of cadmium sulfide nanoparticles and their interaction with hepatocytes

In the current study, β-galactose-carrying lactobionic acid (LA) was conjugated on the surface of mercaptoacetic acid-coated cadmium sulfide nanoparticles (CSNPs) to ensure specific recognition of liver cells (hepatocytes) and to enhance biocompatibility. Maltotrionic acid-coated CSNPs (MCSNPs) were also prepared for use as a control. The results showed that LA-immobilized CSNPs (LCSNPs) were selectively and rapidly internalized into hepatocytes and emitted more intense fluorescence images as well as demonstrated increased biocompatible behavior in vitro than those of CSNPs and MCSNPs. Furthermore, the uptake amount of LCSNPs into hepatocytes was higher than that of CSNPs and MCSNPs. All these results indicate that LCSNPs may find ever-growing applications in biological labels and detection or contrast agents in life science and medical diagnostics.