Journal of biomedical materials research. Part B, Applied biomaterials最新文献

Our laboratory recently developed a new class of high surface area, honeycomb Nanoclay Microsphere Framework absorbents (NMFs) that prompt rapid hemostasis. In the present work, we propose a novel approach to develop antibacterial Topical Hemostatic Agents (THAs) by anchoring silver nanoparticles (AgNPs) onto NMFs. This combination was obtained by a chemical co-reduction approach, followed by freeze-processing, and was shown to ensure stability and on-site delivery of AgNPs, without altering the hemostatic properties of NMFs. Silver-loaded NMFs showed no change in their unique architecture and led to a 55% increase in clot strength, compared to standard control plasma or commercially available THA, and a significant decrease in mean fibrin fiber diameter. Silver nanoparticles were successfully released when solubilized and prevented the growth of both Pseudomonas aeruginosa and Staphylococcus aureus at concentrations of 22 and 30 ppm of silver released, respectively. Overall, cell mortality was between 9.1 ± 5.1% and 6.3 ± 3.2%, depending on AgNP concentration, confirming a low cytotoxicity. Silver-loaded nanoclay microsphere frameworks appear to constitute promising candidates as topical hemostatic agents for secondary management of hemostasis when infection control is needed.

Injectable cell therapies offer several advantages compared with traditional open surgery, including less trauma to the patient, shorter recovery time, and lower risk of infection. However, a significant problem is the difficulty in developing effective cell delivery carriers that are cyto-compatible and maintain cell viability both during and after injection. In the presented study, it was aimed to develop poly(butylene adipate-co-terephthalate) (PBAT) microcarriers using the emulsion preparation-solvent evaporation technique. The optimized diameter of the PBAT microcarriers was determined as 104 ± 15 μm at 700 rpm and there would be no blockage after injection due to the nonswelling feature of microcarriers. Furthermore, the cellular activities of PBAT microcarriers were evaluated in static culture for 7 days using L929 mouse fibroblasts, MC3T3-E1 mouse pre-osteoblasts, and rat adipose-derived mesenchymal cells (AdMSCs). 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide results and Sscanning electron microscope images showed that PBAT microcarriers increased the adhesion and proliferation properties of pre-osteoblasts and stem cells, while L929 fibroblasts formed aggregates by adhering to certain regions of the microcarrier surface and did not spread on the surface. These results emphasize that PBAT microcarriers can be used as injectable carriers, especially in stem cell therapies, but their surface properties need to be modified for some cells.

Calcium phosphate materials, particularly hydroxyapatite (HA), are extensively used in biomedical applications because of their prominence as primary inorganic constituents of human hard tissues. This study investigates the synthesis of HA coatings via spray pyrolysis using various precursors, including HA derived from bovine bone. The effects of pH on the formation and properties of HA coatings were systematically examined. Samples exposed to acidic conditions or left without pH adjustment led to the formation of HA, contrasting with the outcomes observed through dissolution methods. Different characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), were employed to evaluate the quality and crystallinity of the coatings. Among the samples, those exhibiting superior crystallinity and nanostructured features, including bovine HA, were selected for further surface functionalization with the antibiotic enrofloxacin using spin coating. As expected, the antibiotic loading on each material's surface depended on the amount of HA deposited on the substrate. However, the desorption results indicated that, in all cases, desorption persisted beyond 38 h, implying that HA-loaded matrices could be effective systems for controlled and prolonged drug release, which could be useful in dental or orthopedic implants for inhibiting the growth of bacterial biofilms.

The failure of bone regeneration has been considered as a serious problem that troubling patients for decades, most of which was resulted by the poor angiogenesis and chronic inflammation after surgery. Among multiple materials applied in the repair of bone defect, silicate bioceramics attracted researchers because of its excellent bioactivity. The purpose of this study was to detect the effect of specific bioactive glass ceramic (AP40, based on crystalline phases of apatite and wollastonite) on angiogenesis and the subsequent bone growth through the modulation of macrophages. Two groups were included in this study: control group (macrophages without any stimulation, denominated as Control) and AP40 group (macrophages incubated on AP40). This study investigated the effect of AP40 on macrophages polarization (RAW264.7) and angiogenesis in vitro and in vivo. Additionally, the changes of angiogenic ability regulated by macrophages were explored. AP40 showed excellent angiogenesis potential and the expression of CD31 was promoted through the modulation of macrophages toward M2 subtype. Additionally, the macrophages incubated on AP40 synthesized more PDGF-BB comparing to macrophages without any stimulation, which contributed to the improved angiogenetic ability of human umbilical vein endothelial cells (HUVECs). Results of in vivo studies indicated increased bone ingrowth along the implants, which indicated the potential of bioceramics for bone defect repair clinically.

The objective of the present study was to evaluate the carbon fiber obtained from textile PAN fiber, in its different forms, as a potential scaffolds synthetic bone. Thirty-four adult rats were used (Rattus norvegicus, albinus variation), two critical sized bone defects were made that were 5 mm in diameter. Twenty-four animals were randomly divided into four groups: control (C)—bone defect + blood clot, non-activated carbon fiber felt (NACFF)—bone defect + NACFF, activated carbon fiber felt (ACFF)—bone defect + ACFF, and silver activated carbon fiber felt (Ag-ACFF)—bone defect + Ag-ACFF, and was observed by 15 and 60 days for histomorphometric, three-dimensional computerized microtomography (microCT) and mineral apposition analysis. On histomorphometric and microCT analyses, NACFF were associated with higher proportion of neoformed bone and maintenance of bone structure. On fluorochrome bone label, there was no differences between the groups. NACFF has shown to be a promising synthetic material as a scaffold for bone regeneration.

Periosteal expansion osteogenesis (PEO) is a technique for augmenting bone by creating a gradual separation between the bone and periosteum. This study assessed PEO-induced bone formation around the femurs of rats using a dynamic frame device (DFD), consisting of a shape memory membrane made of polyethylene terephthalate (PET) formed into a tubular shape. The DFDs, consisting of a PET membrane coated with hydroxyapatite (HA)/gelatin on the bone-contact surface, were inserted between the periosteum and bone of the femurs of rats. In the experimental group, DFDs were suture-fixed to the femur with 4–0 Vicryl Rapid; in the control group, 4–0 silk thread was used for fixation. Five rats per group were euthanized at intervals of 3, 5, and 8 weeks postoperatively. Bone formation was evaluated via micro-CT imaging, histomorphometry, and histological analysis. Morphological analysis revealed new bone between the femur and the periosteum, expanded by the DFD, in all groups. The mean values of new bone were 0.30 mm² proximally, 0.18 mm² centrally, and 0.82 mm² distally in the control group, compared to 1.05 mm² proximally, 0.27 mm² centrally, and 0.84 mm² distally in the experimental group. A significant difference in new bone was observed in the proximal region of the experimental group. Histological examination showed that a single layer of newly formed neoplastic bone was noted on the cortical bone surface across all sites. The proximal portion displayed a bone marrow cavity at the center, encircled by a thick bone cortex with a layered structure. New bone formation was notable between existing cortical bone and the periosteum, particularly at both ends of the DFD. The use of PET in PEO was a viable option for achieving ideal bone morphology.

Battlefield wounds are at high risk of infection due to gross contamination and delays in evacuation from forward-deployed locations. The aim of this study was to formulate an antibiotic wound gel for application by a field medic in austere environments to protect traumatic wounds from infection during transport. Formulation development was conducted over multiple phases to meet temperature, handling, in vitro elution, and in vivo tissue response requirements. Thermal properties were evaluated by vial inversion, DSC, and syringe expression force in a temperature range of 4–49°C. Handling was evaluated by spreading onto blood-contaminated tissue and irrigation resistance. Controlled antibiotic release was evaluated by a modified USP immersion cell dissolution method. Local tissue effects were evaluated in vivo by subcutaneous implantation in rats for 7 and 28 days. An oleogel composition of cholesterol, hydrogenated castor oil, soybean oil, and glyceryl monocaprylocaprate met the target performance criteria. Peak expression force from a 5 mL syringe at 4°C was 48.3 N, the dropping point temperature was 68°C, and the oleogel formulation could be spread onto blood-contaminated tissue and resisted aqueous irrigation. The formulation demonstrated sustained release of tobramycin in PBS at 32°C for 5 days. Implantation in a rat dorsal pocket demonstrated a slight tissue reaction after 7 days with minimal to no reaction after 28 days, comparable to a commercial hemostat control. Material resorption was evident after 28 days. The formulation met target characteristics and is appropriate for further evaluation in a large animal contaminated blast wound model.

Currently available benchtop (in vitro) aneurysm models are inadequate for testing the efficacy of endovascular device treatments. Specifically, current models do not represent the mechanical instability of giant aneurysms (defined as aneurysms with 25 mm in height or width) and do not predictably rupture under simulated physiological conditions. Hence, in vitro aneurysm models with biomechanically relevant material properties and a predictable rupture timeframe are needed to accurately assess the efficacy of new medical device treatment options. Understanding the material properties of an aneurysm (e.g., shear and compression modulus) as it approaches rupture is a crucial step toward creating a pathologically relevant and sophisticated in vitro aneurysm rupture model. We investigated the change in material properties of a blood vessel, via enzymatic treatment, to simulate the degradation of an aneurysm wall and used this information to create a sophisticated aneurysm rupture model using the latest in additive manufacturing technologies (3D printing) with tissue-like materials. Mechanical properties (shear and compression modulus) of swine carotid vessels were evaluated before and after incubation with collagenase D enzyme (30 min at 37°C) to simulate the effect of biochemical activity on aneurysm wall approaching rupture compared to control vessels (untreated). Mechanical strength of a soft and flexible 3D-printed material (VCA-A30: 30 shore A hardness) was tested for comparison to these arterial vessels. This material was then used to create spherical shaped, giant-sized (25-mm diameter) aneurysm phantoms and were run under neurovascular pressures (120/80 ± 5 mmHg), beats per minute (BPM = 70) and flows representing the middle cerebral artery [MCA: 142.67 (±20.13) mL/min] using a blood analog [3.6 (±0.4) cP viscosity] with non-Newtonian shear-thinning properties. The shear modulus of swine carotid vessel before treatment was 12.2 (±2.7) KPa and compression modulus was 663.5 (±111.6) KPa. After enzymatic treatment by collagenase D, shear modulus of animal tissues reduced by 33% (p-value = .039) while compression modulus remained statistically unchanged (p-value = .615). Control group (untreated vessels) showed minimal reduction (13%, p-value = .226) in shear modulus and 78% increase (p-value = .034) in compression modulus. The shear modulus of the 3D-printed material was 228.59 (±24.82) KPa while its compression modulus was 668.90 (±13.16) KPa. This material was used to prototype a sophisticated in vitro giant aneurysm rupture model. When subjected to physiological pressures and flow rates, the untreated models consistently ruptured at ~12 min. These results indicate that aneurysm rupture can be recreated consistently in a benchtop in vitro model, utilizing the latest 3D-printed materials, connected to a physiologically relevant programmable pump. Further studies will investigate the optimization of various aneurys