Progress in Biomaterials最新文献

Poly(N-vinylcaprolactam) (PNVCL) is a suitable alternative for biomedical applications due to its biocompatibility, biodegradability, non-toxicity, and showing phase transition at the human body temperature range. The purpose of this study was to synthesize a high molecular weight PNVCL-PVAc thermo-responsive copolymer with broad mass distribution suitable for electrospun nanofiber fabrication. The chemical structure of the synthesized materials was detected by FTIR and ¹HNMR spectroscopies. N-Vinyl caprolactam/vinyl acetate copolymers (159,680 molecular weight (g/mol) and 2.51 PDI) were synthesized by radical polymerization. The phase transition temperature of N-vinyl caprolactam/vinyl acetate copolymer was determined by conducting a contact angle test at various temperatures (25, 26, 28, and 30 [Formula: see text]). The biocompatibility of the nanofibers was also evaluated, and both qualitative and quantitative results showed that the growth and proliferation of 929L mouse fibroblast cells increased to 80% within 48 h. These results revealed that the synthesized nanofibers were biocompatible and not cytotoxic. The results confirmed that the synthesized copolymers have good characteristics for biomedical applications.

Despite the importance of porous titanium oxide (PA-TiO₂) in diverse functional applications, very little information is available on the compatible mechanical properties for potential biomedical applications. In this study, PA-TiO₂ foam was synthesized using space-holding powder metallurgy and sintering methods to produce interconnected opened-cell structure with surface morphology of mountain-like features associated with the extensive rift valley system. Three different types of PA-TiO₂ foams with porosities of 35-52% and mean pore diameter of 190-210 μm were fabricated for evaluating the effect of porosity on mechanical properties of bulk PA-TiO₂. The modulus of elasticity of PA-TiO₂ foams exhibited in the range of 45-262 MPa which was within the range of modulus of elasticity of human cancellous bone. Cytotoxicity test is performed in vitro analysis to observe the effect of cell toxicity to produce osteointegration when used as implantable materials. There was no cytotoxicity effect found and remarkable cell growth was observed for human cancerous (HeLa) cell line. However, there was no cytotoxicity effect found and cell growth was not observed for Vero cell line. This study suggested that PA-TiO₂ facilitates cell growth without spreading toxicity and has mechanical properties of cancellous bone. Hence, it has potential application as implant and medical devices in biomedical applications.

Insufficient biological and bioactive properties of dextran hydrogels limit their applications as promising scaffolds for tissue engineering. We developed nanocomposite dextran hydrogels comprised of bioactive glass (nBGC: 64% SiO2, 31% CaO, 5% P₂O₅) nanoparticles with an average particle size of 77 nm using a chemical crosslinking of dextran chains to form 3D hydrogel networks. In the current study; bioactivity of the obtained nanocomposite hydrogels was evaluated through the formation of apatite crystal structures after the incubation in simulated body fluid (SBF) at various submersion periods and nBGC content. The scanning electron microscopy (SEM) micrographs represented an enhanced hydroxyapatite formation on the cross section of nanocomposite comprising of nBGC content from 2 to 8 (% by wt). Biomineralization results of Dex-8 (% by wt) composite during 7, 14 and 28 days immersion indicated the apatite layer formation and the growth of apatite crystal size on the surface and cross section of the nanocomposite. Moreover, MTT assessments indicated that human osteosarcoma cells (SaOS-2) were able to adhere and spread within the dextran hydrogels reinforced with the bioactive glass nanoparticles. With regard to enhanced bioactivity and biocompatibility, the developed dextran-nBGC hydrogel could be considered as a suitable candidate for bone tissue engineering application.

One of the significant challenges in the fabrication of scaffolds for tissue engineering lies in the direct interaction of bioactive agents with cells in the scaffolds matrix, which curbs the effectiveness of bioactive agents resulting in diminished cell recognition and attachment ability of the scaffolds. Here, three-dimensional porous scaffolds were fabricated using polycaprolactone (PCL) and chitosan, by two approaches, i.e., blending and surface coating to compare their overall effectiveness. Blended scaffolds (Chi-PCL) were compared with the scaffolds fabricated using surface coating technique, where chitosan was coated on the pore wall of PCL scaffolds (C-PCL). The C-PCL exhibited a collective improvement in bioactivities of the stem cell on the scaffold, because of the cell compatible environment provided by the presence of chitosan over the scaffolds interface. The C-PCL showed the enhanced cell attachment and proliferation behavior of the scaffolds along with two-fold increase in hemolysis compatibility compared to Chi-PCL. Furthermore, the compression strength in C-PCL increased by 24.52% and 8.62% increase in total percentage porosity compared to Chi-PCL was attained. Along with this, all the bone markers showed significant upregulation in C-PCL scaffolds, which supported the surface coating technique over the conventional methods, even though the pore size of C-PCL was compromised by 19.98% compared with Chi-PCL.

The present study makes assessments by analyzing the efficacy of combined decellularization protocol for human ovarian fragments. Tissues were decellularized by freeze-thaw cycles, and treated with Triton X-100 and four concentrations (0.1, 0.5, 1 and 1.5%) of sodium dodecyl sulfate (SDS) at two exposure times. The morphology and DNA content of decellularized tissues were analyzed, and the group with better morphology and lower DNA content was selected for further assessments. The Acridine orange, Masson's trichrome, Alcian blue, and Periodic Acid-Schiff staining were used for extracellular matrix (ECM) evaluation. The amount of collagen types I and IV, glycosaminoglycans (GAGs), and elastin was quantified by Raman spectroscopy. The fine structure of the scaffold by scanning electron microscopy was studied. The endometrial mesenchymal cells were seeded onto decellularized scaffold by centrifugal method and cultured for 7 days. After 72 h the treated group with 0.5% SDS showed well-preserved ECM morphology with the minimum level of DNA (2.23% ± 0.08). Raman spectroscopy analysis confirmed that, the amount of ECM components was not significantly decreased in the decellularized group (P < 0.001) in comparison with native control. The electron micrographs demonstrated that the porosity and structure of ECM fibers in the decellularized group was similar to native ovary. The endometrial mesenchymal cells were attached and penetrated into the decellularized scaffold. In conclusion this combined protocol was an effective method to decellularize human ovarian tissue with high preservation of ECM contents, and human endometrial mesenchymal cells which successfully interacted with this created scaffold.

Magnetic thermoresponsive nanogels present a promising new approach for targeted drug delivery. In the present study, bovine serum albumin (BSA) loaded thermo-responsive magnetic semi-IPN nanogels (MTRSI-NGs) were developed. At first poly(N-vinyl caprolactam) (PNVCL) was synthesized by free radical polymerization and then MTRSI-NGs were prepared by crosslinking chitosan in presence of chitosan and Fe₃O₄. The formation of MTRSI-NGs has been confirmed by FTIR, and the average molecular weight of PNVCL was determined by GPC analysis. Rheological and turbidimetry analysis were used to determine lower critical solution temperature (LCST) of PNVCL and magnetic thermo-responsive nanogels (MTRSI-NGs) around 32 and 37 °C, respectively. FE-SEM analysis showed particle size at less than 20 nm in the dried state. Dynamic light scattering determined particle size at about 30 nm in a swelling state. The analysis of release behavior showed that the BSA release ratio at 40 °C was faster than 25 °C. The pH release behavior was evaluated at pH 5.5 and 7.4 and showed that the drug release rate at pH 5.5 was more rapid than pH 7.4. The results show MTRSI-NGs are applicable to protein targeted delivery by thermosensitive targeted drug delivery systems.

Niosomes are increasingly explored for enhancing drug penetration and retention in ocular tissues for both posterior and anterior eye delivery. They have been employed in encapsulating both hydrophilic and hydrophobic drugs, but their use is still plagued with challenges of stability and poor entrapment efficiency particularly with hydrophilic drugs. As a result, focus is on understanding the parameters that affect their stability and their optimization for improved results. Pilocarpine hydrochloride (HCl), a hydrophilic drug is used in the management of intraocular pressure in glaucoma. We aimed at optimizing pilocarpine HCl niosomes and evaluating the effect of sonication on its stability-indicating properties such as particle size, polydispersity index (PDI), zeta potential and entrapment efficiency. Pilocarpine niosomes were prepared by ether injection method. Composition concentrations were varied and the effects of these variations on niosomal properties were evaluated. The effects of sonication on niosomes were determined by sonicating optimized drug-loaded formulations for 30 min and 60 min. Tween 60 was confirmed to be more suitable over Span 60 for encapsulating hydrophilic drugs, resulting in the highest entrapment efficiency (EE) and better polydispersity and particle size indices. Optimum sonication duration as a process variable was determined to be 30 min which increased EE from 24.5% to 42% and zeta potential from (-)14.39 ± 8.55 mV to (-)18.92 ± 7.53 mV. In addition to selecting the appropriate surfactants and varying product composition concentrations, optimizing sonication parameters can be used to fine-tune niosomal properties to those most desirable for extended eye retainment and maintenance of long term stability.

The ability to create three-dimensional (3D) cell-incorporated constructs for tissue engineering has progressed tremendously. One of the major challenges that limit the clinical applications of tissue engineering is the inability to form sufficient vascularization of capillary vessels in the 3D constructs. The lack of a functional capillary network for supplying nutrients and oxygen leads to poor cell viability. This paper presents the near-field electrospinning (ES) technique to fabricate a branched microfiber structure that mimics the morphology of capillaries. Polycaprolactone solution was electrospun onto a sloped collector that resulted in morphological and geometric variation of the fibers. With proper control over the solution viscosity and the electrospinning voltage, a single fiber was scattered into a branched fiber network and then converged back to a single fiber on the collector. The obtained fibers have a diameter of less than 100 microns at the two ends with coiled and branched fibers of less than 10 microns that mimics the arteriole-capillary-venule structure. The formation of such a structure in the near-field ES strongly depends on the solution viscosity. Low viscosity solutions form beads and discontinuous lines thus cannot be used to achieve the desired structure. The branching of PCL fiber occurs due to an electrohydrodynamic instability. The transition from the straight large fiber to smaller coiled/branched fibers is not instantaneous and stretches over a horizontal region of 1.5 cm. The current work shows the feasibility of electrospinning the stem-branch-stem fibrous structure by adopting a valley-shaped collector with potentials for tissue engineering applications.

Titanium and its alloys are considered as appropriate replacements for the irreparable bone. Calcium phosphate coatings are widely used to improve the osteoinduction and osseointegration ability of titanium alloys. To further improve the performance of the calcium phosphate-coated implants, strontium (Sr) was introduced to partially replace the calcium ions. In this study, the effect of Sr ion addition on the fluorohydroxyapatite (FHA)-coated Ti6Al4V alloy was investigated and all the coatings were treated under hydrothermal condition. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the phases and microstructures, respectively. Shear tests were done to evaluate the bond strength of the coating layer. MTT, adhesion, and alkaline phosphatase tests were performed to evaluate the biocompatibility and osteogenic behavior of the samples. Results showed that the average crystallite size for the strontium-doped FHA samples was 48 nm and the bond strength had increased 13.15% in comparison with FHA-coated samples. Analysis of variance showed p value for all MTT tests at more than 0.322 and there was not any evidence of cell death after 7 days. The results of the ALP test showed that the increase of the cell activity in Sr samples from day 7 to 14 is three times higher than the FHA ones.