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Bone is the second most common connective tissue worldwide and more than four million bone grafts or substitutes are used annually to treat bone defects. Due to the restrictions of using these therapies, today the development of bioactive 3D scaffolds has become a major field in bone tissue engineering. The main aim of this study was to fabricate polylactic acid/ polycaprolactone bone scaffolds by freeze extraction method. In order to improve the rheological, mechanical and biological properties of these scaffolds, hydroxyapatite, silica and their mixture were used as the filler loaded into scaffolds (35 wt%). All scaffolds were fabricated in three different concentrations of 5, 6.5 and 8% w/w based on polymer to investigate the effect of polymer concentration on their properties. In this regard, to evaluate the surface morphology of scaffolds and the size of pores, SEM analysis and porosity test were used. FTIR analysis was performed to identify functional groups and possible molecular interactions in the scaffold. The degree of degradation of scaffolds was conducted when incubated in PBS and also to better investigate the mechanical properties, a compression test was performed on cylindrical specimens. SEM images indicated that the pores were interconnected in the composite scaffolds and their size varied from 23 to 114 μm. The amount of porosity of the scaffolds made in this project ranged from 62.2 to 84.1%. These values demonstrated that the scaffolds prepared by the freeze extraction method had suitable pore sizes for use in tissue engineering. Considering the morphology and porosity as well as the appropriate pore size distribution in the 6.5% hybrid sample, this scaffold was selected as the optimal scaffold. The results indicated that the hydrophilicity of the scaffold surface was improved by the addition of silica nanoparticles and hydroxyapatite. The use of HA alone improved the mechanical properties of the porous structure, but the addition of SiO2 to HA more effectively strengthened the scaffolds. Furthermore, in samples containing silica, an increase in degradation was observed. According to the results of MTT test, the constructed scaffolds not only did not show cytotoxicity but also increased the rate of cell growth and proliferation. Pathological images showed that ECM deposition and collagen deposition were significantly higher in the hybrid groups from the third week onwards than in the other groups. [ABSTRACT FROM AUTHOR]

3D printing-based technologies can fabricate scaffolds offer great precision to control internal architecture and print complicated structures based upon the defect site. However, the materials used in the direct printing are restricted depending on the printing technology used and the indirect one can overcome this limitation. In the present study, indirect 3D printing approach was used to develop bone scaffolds from polylactic acid/ polycaprolactone/ hydroxyapatite (PLA/PCL/HA) composites. Casting of the composite suspensions was done into a dissolvable 3D printed negative mold, in order to achieve simultaneous macro- and micro-porous composites, using freeze drying/particle leaching method. To evaluate morphology, functional groups, and elemental analysis of the scaffolds, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and energy dispersive spectroscopy (EDS) were respectively used. Scaffolds' porosity was measured with the aid of liquid replacement technique. Also, the mechanical strength of scaffolds was examined by compression test and measuring the compressive modulus Considering the microstructure, porosity and pore size as well as mechanical property, the scaffold composed of PLA/PCL 70/30 w /w and 35% HA was more favorable. The PLA/PCL/HA 70/30–35% scaffold presented a porosity of 77%, an average pore size of 160 μm, and Young's modulus of 1.35 MPa. Cell adhesion, viability and mineral deposits formation for PLA/PCL/HA scaffolds at PLA/PCL ratios of 70/30, 50/50 and 30/70 and the fixed amount of HA (35%) were also studied in vitro by the means of MG63 cells. The cytotoxicity assessment showed that the cells could be viable and proliferate on the scaffolds. The results indicated that composite scaffold with the PLA/PCL weight ratio of70/30 accomplished more favorable properties in terms of biocompatibility, viability, and osteoinduction property. Unlabelled Image • PLA/PCL/HA scaffolds were fabricated by indirect 3D printing method. • Macro- and micro-porous structure was obtained with an appropriate porosity. • Increasing HA resulted in decreased porosity and increased compressive modulus. • PLA rich scaffolds showed higher compressive modulus than PCL rich samples. • The prepared scaffolds were capable of proliferating MG63 cells on their surfaces. [ABSTRACT FROM AUTHOR]

• Bilayered nanofibers of PCL/Gel loaded with n-ZnO and amoxicillin were fabricated. • Scaffolds showed prolonged steady release profile for the drug. • Presence of drug could give antibacterial activity to scaffolds while did not adversely affected their biocompatibility. • Scaffolds accelerated mesenchymal stromal cell proliferation. • Scaffolds promoted angiogenesis and full-thickness wound healing. Treatment of diabetic, chronic, and full-thickness wounds is a challenge as these injuries usually lead to infections that cause delayed and inappropriate healing. Therefore, fabrication of skin scaffolds with prolonged antibacterial properties are of great interest. Due to this demand, bilayered nanofibrous scaffolds were fabricated based on polycaprolactone and gelatin. The top layer of these scaffolds contained amoxicillin as a model drug and the bottom layer was loaded with zinc oxide nanoparticles to accelerate wound healing. Several characterization techniques including FTIR, SEM, swelling, tensile test, in vitro degradation, drug release, antibacterial activity, and MTT assay were used to assess physical, mechanical, and biological properties of produced nanofibers. SEM results demonstrated that bilayered scaffolds have smooth bead-free microstructures while in vitro release test showed that samples have a sustained release for amoxicillin up to 144 h (tested time). Disk diffusion assessment confirmed the potency of scaffolds for hindering bacterial growth while results of cytotoxicity evaluation revealed that scaffolds could effectively accelerate cell proliferation. Finally, in vivo tests on full-thickness rat models revealed that fabricated nanofibers accelerate wound contraction, increase collagen deposition and angiogenesis, and prevent scar formation. Altogether, results showed that fabricated scaffolds are promising candidates for treatment of full-thickness wounds. [ABSTRACT FROM AUTHOR]