Robust Nanofiber Mats Exfoliated From Tussah Silk for Potential Biomedical Applications

Nanofibers as elements for bioscaffolds are pushing the development of tissue engineering. In this study, tussah silk was mechanically disintegrated into nanofibers dispersed in aqueous solution which was cast to generate tussah silk fibroin (TSF) nanofiber mats. The effect of treatment time on the morphology, structure, and mechanical properties of nanofiber mats was examined. SEM indicated decreasing diameter of the nanofiber with shearing time, and the diameter of the nanofiber was 139.7 nm after 30 min treatment. These nanofiber mats exhibited excellent mechanical properties; the breaking strength increased from 26.31 to 72.68 MPa with the decrease of fiber diameter from 196.5 to 139.7 nm. The particulate debris was observed on protease XIV degraded nanofiber mats, and the weight loss was greater than 10% after 30 days in vitro degradation. The cell compatibility experiment confirmed adhesion and spreading of NIH-3T3 cells and enhanced cell proliferation on TSF nanofiber mats compared to that on Bombyx mori silk nanofiber mats. In conclusion, results indicate that TSF nanofiber mats prepared in this study are mechanically robust, slow biodegradable, and biocompatible materials, and have promising application in regenerative medicine.

Biomineralized Composite Liquid Crystal Fiber Scaffold Promotes Bone Regeneration by Enhancement of Osteogenesis and Angiogenesis

Liquid crystals (LCs) are appealing biomaterials for applications in bone regenerative medicine due to their tunable physical properties and anisotropic viscoelastic behavior. This study reports a novel composite poly (L-lactide) (PLLA) scaffold that is manufactured by a simple electrospinning and biomineralization technique that precisely controls the fibrous structure in liquid LC phase. The enriched-LC composites have superior mineralization ability than neat PLLA; furthermore BMSC cells were inoculated onto the HAP-PLLA/LC with hydroxyapatite (HAP) composite scaffold to test the capability for osteogenesis in vitro. The results show that the PLLA/LC with HAP produced by mineralization leads to better cell compatibility, which is beneficial to cell proliferation, osteogenic differentiation, and expression of the angiogenic CD31 gene. Moreover, in vivo studies showed that the HAP-PLLA/LC scaffold with a bone-like environment significantly accelerates new and mature lamellar bone formation by development of a microenvironment for vascularized bone regeneration. Thus, this bionic composite scaffold in an LC state combining osteogenesis with vascularized activities is a promising biomaterial for bone regeneration in defective areas.

Development of an in-situ printing system with human platelet lysate based bioink to treat corneal perforation

Purpose: Corneal perforation is a clinical emergency. Tissue glue to seal the perforation, and supplementary topical medication represents existing standard treatment. Previously, our group developed a transparent bioink that showed good cell compatibility and accelerated corneal epithelial cells healing in-vitro. This study aims to develop a novel treatment method for corneal perforation using this bioink. Methods: Rheometry was used to measure bioink behaviour at room and corneal surface temperatures. Bioink adhesiveness to porcine skin and burst pressure limit were also measured. Based on rheological behaviour, a hand-held biopen was developed to extrude the bioink onto the cornea. An animal trial (5 New Zealand white rabbits) to compare bioink and cyanoacrylate glue (control group) impact on a 2mm perforation was conducted to evaluate safety and efficacy. Results: Bioink has higher adhesiveness compared to commercial fibrin glue and can withstand burst pressure approximately 6.4x higher than routine intraocular pressure. Bioink-treated rabbits had lower pain score and faster recovery, despite generating similar scar-forming structure after healing compared to controls. No secondary corneal ulcer was generated in rabbits treated with bioink. Conclusions: This study reports a novel in-situ printing system capable of delivering a transparent bioink to the cornea and successfully treating small corneal perforations. Bioink-treated rabbits recovered faster to completely healed perforation and required no additional analgesia. Both groups showed scarred corneal tissue after healing, however no infection and inflammation was observed 3 weeks. The delivery system was easy to use and may represent an alternative treatment for corneal perforation.

Antibacterial performance of Berberine loaded carrageenan/konjac glucomannan hydrogels

Carrageenan and konjac glucomannan are non-toxic polysaccharides which have been widely applied in the biomedical fields. Berberine as the antibacterial agent was successfully loaded into carrageenan/konjac glucomannan hydrogels. The Berberine loaded carrageenan/konjac glucomannan dried hydrogels display three-dimensional network structure, good swelling behavior and high porosity. These dried hydrogels also show controlled release behavior of Berberine. A good antibacterial effect towards S. aureus and C. albicans with good cell compatibility is exhibited. Thus, the fabricated Berberine loaded carrageenan/konjac glucomannan dried hydrogels could be considered as novel antibiotic alternative antibacterial materials.

Osteoblast-like Cell Proliferation, ALP Activity and Photocatalytic Activity on Sintered Anatase and Rutile Titanium Dioxide

This study aimed to create a biomaterial from titanium dioxide (TiO2), which has been known to have photocatalytic and bone formation promoting effects. I expected that anatase titanium dioxide-based implants could promote bone augmentation and induce bone formation. Powdery anatase TiO2 was compression molded and sintered at 700, 800, 900, and 1000 °C to prepare sintered compact samples. X-ray diffraction and scanning electron microscopy were used to observe the surface of these samples. Furthermore, mouse osteoblast-like cells (MC3T3-E1 cell line) were seeded on the samples sintered at different temperatures, and cell proliferation was observed to evaluate the cell proliferation of the samples. The sample sintered at 700 °C was composed of anatase TiO2. The samples sintered at 800 °C and 900 °C were confirmed to consist of a mixture of anatase and rutile TiO2 crystalline phases. Moreover, the sample sintered at 700 and 800 °C, which contained anatase TiO2, showed remarkable photocatalytic activity. Those samples sintered at 1000 °C were transformed to the rutile TiO2. The cell proliferation after 7–14-days culturing revealed that cells cultured on the 700 °C sample decreased in number immediately after initiation of culturing. The cells cultured on TiO2 sintered at 900 °C markedly proliferated over time with an increase in the alkaline phosphatase activity, showing good MC3T3-E1 cell compatibility of the samples. The sample sintered at 1000 °C, which is rutile TiO2, showed the highest increase.

Surface Modification of Titanium by Cobalt-Containing Plasma Electrolytic Oxidation Promotes Osteogenic Response

Titanium (Ti) is a widely used metallic biomaterial in developing orthopedic implants or devices, but it is often encountered with a poor osteogenic response. In this study, the authors report the surface modification of Ti with cobalt (Co)-containing titanium dioxide (TiO2) coatings by plasma oxidation technique in order to enhance its cellular response. The results were compared between unmodified and surface modified Ti. The scanning electron microscopy (SEM) analysis showed that the surface coating was homogenous and porous throughout the test specimen. Indeed, the energy-dispersive X-ray spectrometry (EDS) analysis showed that the cobalt was evenly distributed on the Ti surface. It was also observed from the preliminary cell culture studies that the surfacemodified Ti has excellent cell compatibility and has promoted the adhesion and proliferation of osteoblasts when compared to the unmodified Ti. The present study clearly demonstrated that the Co-containing plasma electrolytic oxidation is an efficient technique for the surface modification of Ti in order to promote its osteogenic response.

Vancomycin Hydrochloride Loaded Hydroxyapatite Mesoporous Microspheres with Micro/Nano Surface Structure to Increase Osteogenic Differentiation and Antibacterial Ability

As infection induced by the implant will lead to operation failure, the implant material must be endowed with certain antibacterial properties. Hydroxyapatite (HA) mesoporous microspheres have been widely used in bone repair due to their advantages, including simple synthesis, good osteogenic properties and drug loading capacity. In this study, vancomycin hydrochloride-loaded mesoporous hydroxyapatite microspheres with micro/nanosurface structures were synthesized to increase osteogenic differentiation and antibacterial ability. Phytic acid (IP6) was used as a template to prepare mesoporous hydroxyapatite microspheres composed of fibres, flakes and smooth surfaces by the hydrothermal homogeneous precipitation method, and the corresponding specific surface areas were 65.20 m2/g, 75.13 m2/g and 71.27 m2/g, respectively. Vancomycin hydrochloride (Van) was used as the drug model to study the drug loading and release characteristics of the microspheres, as well as the in vitro antibacterial properties after treatment. In addition, during cocultivation with MC3T3-E1 preosteoblasts, HA microspheres assembled via flakes exhibited better cell compatibility, which promoted cell proliferation, alkaline phosphatase (ALP) activity, and the formation of calcium nodules and increased the expression of osteogenic differentiation-related proteins such as Runx-2, osteopontin (OPN) and collagen I (COL I). These results indicated that the HA microspheres prepared in this experiment have broad application prospects in drug delivery systems and bone repair.

Characteristics of Biodegradable Gelatin Methacrylate Hydrogel Designed to Improve Osteoinduction and Effect of Additional Binding of Tannic Acid on Hydrogel

In this study, a hydrogel using single and double crosslinking was prepared using GelMA, a natural polymer, and the effect was evaluated when the double crosslinked hydrogel and tannic acid were treated. The resulting hydrogel was subjected to physicochemical property evaluation, biocompatibility evaluation, and animal testing. The free radicals generated through APS/TEMED have a scaffold form with a porous structure in the hydrogel, and have a more stable structure through photo crosslinking. The double crosslinked hydrogel had improved mechanical strength and better results in cell compatibility tests than the single crosslinked group. Moreover, in the hydrogel transplanted into the femur of a rat, the double crosslinked group showed an osteoinductive response due to the attachment of bone minerals after 4 and 8 weeks, but the single crosslinked group did not show an osteoinductive response due to rapid degradation. Treatment with a high concentration of tannic acid showed significantly improved mechanical strength through H-bonding. However, cell adhesion and proliferation were limited compared to the untreated group due to the limitation of water absorption capacity, and no osteoinduction reaction was observed. As a result, it was confirmed that the treatment of high-concentration tannic acid significantly improved mechanical strength, but it was not a suitable method for improving bone induction due to the limitation of water absorption.