Materials science & engineering. C, Materials for biological applications最新文献

Porous Ti6Al4V scaffolds are characterized by high porosity, low elastic modulus, and good osteogenesis and vascularization, which are expected to facilitate the repair of large-scale bone defects in future clinical applications. Ti6Al4V scaffolds are divided into regular and irregular structures according to the pore structure, but the pore structure more capable of promoting bone regeneration and angiogenesis has not yet been reported. The purpose of this study was to explore the optimal pore structure and pore size of the Ti6Al4V porous scaffold for the repair of large-area bone defects and the promotion of vascularization in the early stage of osteogenesis. 7 groups of porous Ti6Al4V scaffolds, named NP, R8, R9, R10, P8, P9 and P10, were fabricated by Electron-beam-melting (EBM). Live/dead staining, immunofluorescence staining, SEM, CCK8, ALP, and PCR were used to detect the adhesion, proliferation, and differentiation of BMSCs on different groups of scaffolds. Hematoxylin-eosin (HE) staining and Van Gieson (VG) staining were used to detect bone regeneration and angiogenesis in vivo. The research results showed that as the pore size of the scaffold increased, the surface area and volume of the scaffold gradually decreased, and cell proliferation ability and cell viability gradually increased. The ability of cells to vascularize on scaffolds with irregular pore sizes was stronger than that on scaffolds with regular pore sizes. Micro-CT 3D reconstruction images showed that bone regeneration was obvious and new blood vessels were thick on the P10 scaffold. HE and VG staining showed that the proportion of bone area on the scaffolds with irregular pores was higher than that on scaffolds with regular pores. P10 had better mechanical properties and were more conducive to bone tissue ingrowth and blood vessel formation, thereby facilitating the repair of large-area bone defects.

3D printing enables a better control over the microstructure of bone restoring constructs, addresses the challenges seen in the preparation of patient-specific bone scaffolds, and overcomes the bottlenecks that can appear in delivering drugs/growth factors promoting bone regeneration. Here, 3D printing is employed for the fabrication of an osteogenic construct made of hydrogel nanocomposites. Alginate dialdehyde-gelatin (ADA-GEL) hydrogel is reinforced by the incorporation of bioactive glass nanoparticles, i.e. mesoporous silica-calcia nanoparticles (MSNs), in two types of drug (icariin) loading. The composites hydrogel is printed as superhydrated composite constructs in a grid structure. The MSNs not only improve the mechanical stiffness of the constructs but also induce formation of an apatite layer when the construct is immersed in simulated body fluid (SBF), thereby promoting cell adhesion and proliferation. The nanocomposite constructs can hold and deliver icariin efficiently, regardless of its incorporation mode, either as loaded into the MSNs or freely distributed within the hydrogel. Biocompatibility tests showed that the hydrogel nanocomposites assure enhanced osteoblast proliferation, adhesion, and differentiation. Such optimum biological properties stem from the superior biocompatibility of ADA-GEL, the bioactivity of the MSNs, and the supportive effect of icariin in relation to cell proliferation and differentiation. Taken together, given the achieved structural and biological properties and effective drug delivery capability, the hydrogel nanocomposites show promising potential for bone tissue engineering.

Corneal opacities are the 4th leading cause of blindness, and the only current treatment method is the replacement of damaged tissue with a donor cornea. The worldwide shortage of donor eye bank tissue has influenced research into biomaterial substrates for both partial and full thickness corneal implantation. Here, polymer hydrogels based on natural peptides, poly-ɛ-lysine and gellan gum, can be manufactured using reactive inkjet printing (RIJ). The inks used for printing were optimised based on their rheological properties. Printing alternating layers of ink forms a unique surface pattern, based on the immediate formation of ionic bonds between polymers of opposing charges. This surface pattern resembles a repeating honeycomb-like structure, visible by both optical and scanning electron microscopy. The structure of the printed hydrogels can be modified to include pores, a feature of interest for the tissue engineering of full thickness corneal constructs. Printed poly-ɛ-lysine/gellan gum hydrogels demonstrated a transparency of 80% and cyto-compatibility with both corneal epithelial and endothelial cells. Both corneal cell types demonstrated cell attachment across the surface of the printed hydrogel arrays, displaying their typical cell morphology. This gives confidence of the cyto-compatibility of these hydrogels in vitro. Reactive inkjet printing can produce 3D structures with a high resolution, producing printed tracks in the micron range. Additionally, RIJ demonstrates versatility, as constructs can be tailored to meet various dimension and thickness requirements. Furthermore, this work demonstrates for the first time that reactive inkjet printing can been used to produce hydrogel constructs based on these two inks, with the aim of producing constructs for corneal tissue engineering.

Efficient wound treatments to target specific events in the healing process of chronic wounds constitute a significant aim in regenerative medicine. In this sense, nanomedicine can offer new opportunities to improve the effectiveness of existing wound therapies. The aim of this study was to develop catechol bearing polymeric nanoparticles (NPs) and to evaluate their potential in the field of wound healing. Thus, NPs wound healing promoting activities, potential for drug encapsulation and controlled release, and further incorporation in a hydrogel bioink formulation to fabricate cell-laden 3D scaffolds are studied. NPs with 2 and 29 M % catechol contents (named NP2 and NP29) were obtained by nanoprecipitation and presented hydrodynamic diameters of 100 and 75 nm respectively. These nanocarriers encapsulated the hydrophobic compound coumarin-6 with 70% encapsulation efficiency values. In cell culture studies, the NPs had a protective effect in RAW 264.7 macrophages against oxidative stress damage induced by radical oxygen species (ROS). They also presented a regulatory effect on the inflammatory response of stimulated macrophages and promoted upregulation of the vascular endothelial growth factor (VEGF) in fibroblasts and endothelial cells. In particular, NP29 were used in a hydrogel bioink formulation using carboxymethyl chitosan and hyaluronic acid as polymeric matrices. Using a reactive mixing bioprinting approach, NP-loaded hydrogel scaffolds with good structural integrity, shape fidelity and homogeneous NPs dispersion, were obtained. The in vitro catechol NPs release profile of the printed scaffolds revealed a sustained delivery. The bioprinted scaffolds supported viability and proliferation of encapsulated L929 fibroblasts over 14 days. We envision that the catechol functionalized NPs and resulting bioactive bioink presented in this work offer promising advantages for wound healing applications, as they: 1) support controlled release of bioactive catechol NPs to the wound site; 2) can incorporate additional therapeutic functions by co-encapsulating drugs; 3) can be printed into 3D scaffolds with tailored geometries based on patient requirements.

Calcium phosphate coating is an attractive surface modification strategy for magnesium alloys, since it can increase their corrosion resistance and endow them with osteogenic function simultaneously. Herein, a calcium metaphosphate (CMP) coating was fabricated on magnesium alloy by using sol-gel approach assisted with micro-arc oxidation pre-treatment. Scanning electron microscopy showed that the micro-pores and cracks in micro-arc oxidation inner layer generated during the pre-treatment process were sealed by the grainy sol-gel outer layer. Energy dispersive spectrometry and X-ray diffraction results demonstrated the identity of the coating as CMP. The cross-cut test showed that the adhesion of CMP coating was strong. Applying bare magnesium alloy substrate as a control, the CMP coating surface was rougher and more hydrophilic. The potentiodynamic polarization test demonstrated that the corrosion resistance was significantly improved by using CMP coating. Hydrogen evolution in immersion test further confirmed that the degradation rate was decelerated within 14 days. Moreover, CMP coating facilitated the adhesion speed, spreading area, and focal adhesion formation of bone marrow stem cells. The number of cells in the active proliferating state and proliferated cells present on the CMP coating also increased. Additionally, CMP coating upregulated alkaline phosphatase activity and osteogenic gene expression in cells. In summary, the micro-arc oxidation assisted sol-gel CMP coatings increased the corrosion resistance and promoted the interfacial cell behavior for magnesium alloy implants, which might inform the further development of surface modifications on magnesium alloys for bone related applications.