Biocomposites reinforced by fibers or tubes as scaffolds for tissue engineering or regenerative medicine

Antibacterial nanofibrous scaffolds with lowered cytotoxicity using keratin extracted from quail feathers

This study aims to extract keratin from quail feather wastes and incorporate it with silver nanoparticles into a synthetic biodegradable polymer in order to fabricate a nanofibrous scaffold with improved biomedical properties. Polyvinyl alcohol was used as the host polymer and spinning dopes with different amounts (0, 0.15, and 0.75 wt %) of extracted keratin and the same amount of silver nanoparticles prepared in order to fabricate scaffolds. According to the results, the scaffolds with a higher amount of extracted keratin (i.e. 0.75 wt %) provided less bead formation and more uniformity; also, they gave 99.9% and 98% of the antibacterial activity against gram negative ( Escherichia coli) and gram positive ( Staphylococcus aureus) bacteria, respectively. The analysis of the biological response of fibroblast cells cultured on the synthetic scaffolds exhibited remarkable improvement in comparison to the pristine (polyvinyl alcohol-Ag) scaffolds. This article concludes that the addition of extracted keratin into a polymeric matrix (polyvinyl alcohol) can improve both antibacterial properties and cell viability for the resultant scaffolds, and this qualifies them as potent candidates for biomedical applications.

Resin composites reinforced by nanoscaled fibers or tubes for dental regeneration

It has been stated clearly that nanofillers could make an enhancement on the mechanical performances of dental composites. In order to address current shortage of traditional dental composites, fillers in forms of nanofibers or nanotubes are broadly regarded as ideal candidates to greatly increase mechanical performances of dental composites with low content of fillers. In this review, the efforts using nanofibers and nanotubes to reinforce mechanical performances of dental composites, including polymeric nanofibers, metallic nanofibers or nanotubes, and inorganic nanofibers or nanotubes, as well as their researches related, are demonstrated in sequence. The first purpose of current paper was to confirm the enhancement of nanofibers or nanotubes' reinforcement on the mechanical performances of dental restorative composite. The second purpose was to make a general description about the reinforcement mechanism of nanofibers and nanotubes, especially, the impact of formation of interphase boundary interaction and nanofibers themselves on the advanced mechanical behaviors of the dental composites. By means of the formation of interface interaction and poststretching nanofibers, reinforced effect of dental composites by sorts of nanofibers/nanotubes has been successfully obtained.

Carbon nanotubes reinforced composites for biomedical applications

This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

Vascularization of Nanohydroxyapatite/Collagen/Poly(L-lactic acid) Composites by Implanting Intramuscularly In Vivo

It still remains a major challenge to repair large bone defects in the orthopaedic surgery. In previous studies, a nanohydroxyapatite/collagen/poly(L-lactic acid) (nHAC/PLA) composite, similar to natural bone in both composition and structure, has been prepared. It could repair small sized bone defects, but they were restricted to repair a large defect due to the lack of oxygen and nutrition supply for cell survival without vascularization. The aim of the present study was to investigate whether nHAC/PLA composites could be vascularized in vivo. Composites were implanted intramuscularly in the groins of rabbits for 2, 6, or 10 weeks (n=5×3). After removing, the macroscopic results showed that there were lots of rich blood supply tissues embracing the composites, and the volumes of tissue were increasing as time goes on. In microscopic views, blood vessels and vascular sprouts could be observed, and microvessel density (MVD) of the composites trended to increase over time. It suggested that nHAC/PLA composites could be well vascularized by implanting in vivo. In the future, it would be possible to generate vascular pedicle bone substitutes with nHAC/PLA composites for grafting.

Enhancement of VEGF on Axial Vascularization of Nano-HA/Collagen/PLA Composites: A Histomorphometric Study on Rabbits

The aim of this study was to investigate whether the nanohydroxyapatite/collagen/poly(L-lactic acid) (nHAC/PLA) composite is suitable to be compounded with VEGF to enhance the axial vascularization in vivo. Thirty rabbits were divided into 2 groups of 15 animals each. In control group, a nHAC/PLA scaffold slice was vascularized axially by an inserted ligated femoral arteriovenous (AV) bundle in the animal. In experimental group, a slice compounded with VEGF gel was applied. The rabbits were sacrificed at 2 weeks, 6 weeks, and 10 weeks after surgery; the specimens of scaffold slices underwent histomorphometric examination; analysis of the microvessel density (MVD) of both groups was done. The combination with VEGF (Group B) did not enhance the vascularization in early phase (2 and 6 weeks,P>0.05) but worked in later phase (10 weeks,P<0.05). The data of the experiment demonstrated the suitability of the nHAC/PLA composite as carrier for the growth factor VEGF, enabling its sustained release in bioactive form with enough binding efficacy.

The Development of Biomimetic Spherical Hydroxyapatite/Polyamide 66 Biocomposites as Bone Repair Materials

A novel biomedical material composed of spherical hydroxyapatite (s-HA) and polyamide 66 (PA) biocomposite (s-HA/PA) was prepared, and its composition, mechanical properties, and cytocompatibility were characterized and evaluated. The results showed that HA distributed uniformly in the s-HA/PA matrix. Strong molecule interactions and chemical bonds were presented between the s-HA and PA in the composites confirmed by IR and XRD. The composite had excellent compressive strength in the range between 95 and 132 MPa, close to that of natural bone.In vitroexperiments showed the s-HA/PA composite could improve cell growth, proliferation, and differentiation. Therefore, the developed s-HA/PA composites in this study might be used for tissue engineering and bone repair.

The application of fiber-reinforced materials in disc repair

The intervertebral disc degeneration and injury are the most common spinal diseases with tremendous financial and social implications. Regenerative therapies for disc repair are promising treatments. Fiber-reinforced materials (FRMs) are a kind of composites by embedding the fibers into the matrix materials. FRMs can maintain the original properties of the matrix and enhance the mechanical properties. By now, there are still some problems for disc repair such as the unsatisfied static strength and dynamic properties for disc implants. The application of FRMs may resolve these problems to some extent. In this review, six parts such as background of FRMs in tissue repair, the comparison of mechanical properties between natural disc and some typical FRMs, the repair standard and FRMs applications in disc repair, and the possible research directions for FRMs' in the future are stated.

Vascularized bone tissue formation induced by fiber-reinforced scaffolds cultured with osteoblasts and endothelial cells

The repair of the damaged bone tissue caused by damage or bone disease was still a problem. Current strategies including the use of autografts and allografts have the disadvantages, namely, diseases transmission, tissue availability and donor morbidity. Bone tissue engineering has been developed and regarded as a new way of regenerating bone tissues to repair or substitute damaged or diseased ones. The main limitation in engineering in vitro tissues is the lack of a sufficient blood vessel system, the vascularization. In this paper, a new-typed hydroxyapatite/collagen composite scaffold which was reinforced by chitosan fibers and cultured with osteoblasts and endothelial cells was fabricated. General observation, histological observation, detection of the degree of vascularization, and X-ray examination had been done to learn the effect of vascularized bone repair materials on the regeneration of bone. The results show that new vessel and bone formed using implant cultured with osteoblasts and endothelial cells. Nanofiber-reinforced scaffold cultured with osteoblasts and endothelial cells can induce vascularized bone tissue formation.