Bio-medical materials and engineering最新文献

Background: Glioblastoma multiforme (GBM) is the most common type of brain tumor and it is considered as one of the most aggressive malignancies (1.5 years of survival rate).

Objective: Determine the antitumor potential of bismuth lipophilic nanoparticles (BisBAL NP) on a human glioblastoma cell-line.

Methods: BisBAL NP were characterized by scanning electron microscopy (SEM). BisBAL NP entry and intracellular distribution on U-87 MG cells were observed by transmission electron microscopy (TEM). The effect of BisBAL NP on tumor cells was evaluated by MTT assay (IC₅₀ value), Calcein AM staining, Live/dead assay, apoptosis quantification, and comet assay.

Results: BisBAL NP-induced cytotoxicity more efficient than temozolomide (TMZ). The IC₅₀ value of BisBAL NP was 12.7 µM. For the first time, direct interaction between BisBAL NP and plasmatic U-87 MG cell membrane was obtained by TEM. Calcein AM assay revealed loss of permeability of tumor cells after 24 h-exposure to 25 µM of BisBAL NP. 25 µM of BisBAL induced 48.5% of apoptosis, while 50 µM of BisBAL induced a higher rate of apoptosis 77.2%.

Conclusion: BisBAL NP inhibited U-87 MG cell growth through membrane attack and loss membrane permeability, apoptosis induction and later promoting genotoxicity among tumor cells.

A composite of polyvinyl alcohol (PVA) and beta-tricalcium phosphate (β-TCP) was synthesized as a biomaterial filament for 3D printers and its analytical and chemical evaluation was performed. PVA powder and β-TCP were mixed in the range of 0-20 wt% and hot-melt extruded at 200 °C using a single-screw extruder. Comprehensive material characterization of the synthesized filament was performed by powder X-ray diffraction (XRD), near-infrared spectroscopy (NIR), and scanning electron microscopy (SEM). XRD analysis confirmed that the amorphous nature of PVA and the crystalline nature of β-TCP coexisted and the physical mixture state was well maintained. In near-infrared spectroscopy, concentration-dependent spectral changes were observed by normalization, and principal component analysis showed that the first principal component explained 85.6% of the variance. In machine learning regression analysis, partial least squares regression (PLS), random forest (RF), and support vector machine (SVM) were compared, and SVM achieved the best prediction accuracy (R² = 0.910). SEM observations confirmed streaky structures along the extrusion direction and uniform dispersion of β-TCP particles. This study demonstrated that a combined NIR spectroscopy and machine learning approach is effective as a non-destructive quality evaluation technique for composite filaments for 3D printing. This technique enables real-time composition monitoring and quality control of biomaterial filaments, and is expected to be applied to the manufacturing of patient-specific biomedical devices.

Background: Vertically oriented femoral neck fractures are a challenge for orthopedic surgeons, and the complication rates are also high. Recently, several innovative devices have been proposed, such as the proximal femoral bionic nail, InterTAN, and medial buttress plate combined with cannulated screws, to increase the stability of fixation. However, the differences among these innovative devices need to be addressed.

Objective: This study aimed to compare the stability of the proximal femoral bionic nail, InterTAN, and medial buttress plate combined with cannulated screws for vertically oriented femoral neck fractures. Additionally, traditional fixation devices-including three parallel cannulated screws, a compression hip screw system, and a proximal femoral nail-were included for comparison, resulting in a total of six distinct devices evaluated in this study.

Methods: A finite element model of a femoral neck fracture fixed with the six internal fixation devices was created. Furthermore, two different fracture conditions-with and without a 1-mm fracture gap-were considered. The maximum loading during level walking was applied to the model for comparison.

Results: The results indicated that the InterTAN has the best ability to maintain the gap and prevent collapse. Under the fracture gap condition, the peak displacement of the femoral head was smaller in the innovative devices compared to the traditional ones. Specifically, the peak displacements were 1.98 mm for the medial buttress plate combined with cannulated screws, 2.12 mm for the proximal femoral bionic nail, and 1.16 mm for the InterTAN system. The von Mises stress in the medial buttress plate was also the highest among the devices, with values of 1000 MPa with the gap and 1477 MPa without the gap.

Conclusion: Based on the present results, the medial buttress plate combined with cannulated screws, proximal femoral bionic nail, and InterTAN are recommended for cases without a fracture gap, while the InterTAN is recommended for cases with a fracture gap to prevent bone shortening.

BackgroundMonopolar Radiofrequency uses high-frequency waves to generate heat for skin tightening and tissue repair. However, individual fat layer thickness variation causes uneven radiofrequency (RF) penetration and heat thresholds, compromising personalized results.ObjectiveThe purpose of this study is to analyze the temperature distribution of tissues with different fat thickness after radio frequency treatment and the experimental temperature distribution and tissue changes of pork tissues in vitro by finite element analysis and in vitro experiment verification, so as to achieve appropriate energy parameters for different individuals.MethodsA two-dimensional bio-thermal model including epidermis, dermis and subcutaneous tissue was developed in COMSOL Multiphysics 6.2. Four fat thicknesses (2, 4, 6, and 8 mm) were simulated to assess their impact on dermal temperature distribution during 6.78 MHz, 120 W radiofrequency exposure. The electromagnetic-thermal coupling effects were validated through in vitro experiments.ResultsExperimental results validate the simulations, demonstrating consistent thermal trends across fat thicknesses (2-8 mm). Post-treatment intratissue temperatures reached 69  °C (2 mm), 60 °C (4 mm), 55 °C (6 mm), and 45 °C (8 mm), all within epidermal safety limits.ConclusionThe results show that the energy parameters need to be adjusted according to the thickness of adipose tissue during radiofrequency therapy, and higher energy or longer treatment time may be needed for the treatment site with thicker adipose tissue to achieve the expected effect.

BackgroundCardiovascular diseases are the leading cause of mortality worldwide, with coronary artery bypass grafting being the most effective treatment for severe cases. While autografts are preferred, donor veins are often limited. Human umbilical arteries (hUAs) show promise as an alternative. However, to make vascular graft by decellularization, a traditional chemical method can damage tissue structure and function.ObjectiveThis study aims to evaluate the shortening of treatment time and the hUA decellularization efficiency of the perfusion bioreactor systems.MethodshUAs were perfused with 1% Triton X-100 for 6 h, followed by two different concentrations of (0.5% and 1%) SDS for 18 h, and subsequently subjected to a washing procedure. The decellularization process was evaluated using histological staining and DNA quantification, along with tests for cytotoxicity, cell adhesion and proliferation.ResultsThe 0.5% SDS protocol proved most effective, reducing residual DNA to below 50 ng/mg of dry weight while preserving collagen structure. It showed no cytotoxicity to L929 cells, SEM analysis confirmed human umbilical vein endothelial cell (HUVEC) attachment and CCK-8 testing showed promoted HUVECs proliferation.ConclusionThe decellularization protocol of perfusing through 1% TX for 6 h and 0.5% SDS for 18 h through the perfusion bioreactor system is efficient in the intact hUAs tissue. This sets the stage for future in vivo studies and potential clinical applications.

BackgroundSitting on a chair is an essential part of daily life, however the posture is a heavy burden on the lower back, leading to lower back pain.ObjectiveIn this study, lumbar stress distribution was analyzed when sitting on a chair with different backrest inclination, sitting distance and seat pan inclination in order to visualize the stress on intervertebral discs and sacroiliac joints (SIJs).MethodsBody pressure distribution was measured on backrests and seat pans of six subjects. Each sitting posture on a chair was reproduced using a finite element model of a spine and pelvis, and the stress distribution in the lower back was analyzed based on the results of the body pressure distribution measurements.ResultsWhen the seat pan was tilted forward, the pressure on the backrest decreased, whereas the pressure increased with large sitting distance. Finite element analyses showed that equivalent stresses on the SIJs and intervertebral discs was decreased when sitting on a chair shallowly and with the seat pan tilted forward.ConclusionBoth sitting shallowly and with a forward-tilted seat are postures that increase the trunk-thigh angle, and the load on the lower back was reduced by reducing the moment applied to the sacrum.

BackgroundThere are different surgical procedures to fix femoral head-neck fractures, such as total hip arthroplasty and hemiarthroplasty. Under optimal conditions, the inserted prosthesis should last a long time, possibly a lifetime, with only trace amounts of wear each year due to the friction between the femur bone and the prosthesis stem. However, in some cases, failure due to excessive wear, creep, fatigue, corrosion, etc., can occur.ObjectiveThis study investigates the failure causes of a Thompson hip prosthesis both experimentally and numerically.MethodsThe stem of the prosthesis, which is inserted into the femur, broke inside a patient's body over time. Following the removal surgery, the severely damaged and fractured stem was examined to determine the root causes of the failure. For this purpose, fractographic examination of the fractured surfaces was conducted with scanning electron microscope (SEM). Microstructural analyses were performed using optical microscope, and the chemical composition of the prosthesis was analyzed with energy dispersive spectroscopy (EDS). Vickers hardness (HV30) test was conducted on the femoral stem. Additionally, finite element method (FEM) was applied to estimate the forces acting on the prosthesis.ResultsIt was observed that fatigue cracks initiated and propagated from the outer surface of the femoral stem at locations very close to the maximum von Mises stresses observed in the FEM analysis. However, the load magnitudes in the FEM analysis were not high enough to initiate any cracks.ConclusionIt is considered that crack initiation occurred due to material defects from the prosthesis manufacturing process, and the cyclic loading during body motion propagated these cracks. Ultimately, the fracture of the Thompson hip prosthesis occurred.

BackgroundBone filling materials that match the mechanical properties of normal cancellous bone may be more suitable for vertebroplasty to improve the complications caused by osteoporosis.ObjectiveTo prepare and evaluate a new bone filling material (NBFM) that matches the mechanical properties of normal cancellous bone for vertebroplasty.MethodsA new bone filling material (NBFM) was prepared and its biomechanical properties were compared with those of polymethyl methacrylate (PMMA) bone filling material commonly used in clinical vertebroplasty. Finite element analysis was conducted to compare the biomechanical differences between NBFM and PMMA. The lumbar spine model's biomechanical differences were assessed under four different loading conditions: flexion, extension, left flexion, and right flexion.ResultsThe NBFM demonstrated biomechanical properties more closely matching normal cancellous bone compared to PMMA. The finite element analysis revealed that the lumbar spine model with NBFM exhibited improved biomechanical behavior under the specified loading conditions.Conclusion:Bone filling materials that match the mechanical properties of normal cancellous bone, such as the newly developed NBFM, are more suitable for vertebroplasty and may help reduce complications associated with osteoporosis.

Background: Aqueous solubility of pharmaceuticals is a factor as it is directly associated with bioavailability; accordingly, strategies to enhance solubility have been well investigated. Objectives: The purpose of this study was to determine the effects of coamorphization on meloxicam (MX) and saccharine (SA) mixtures. Methods: An equimolar mixture of MX and SA was ground for 4 h at 300 rpm. The obtained samples were evaluated using Fourier-transform mid-infrared spectroscopy, Fourier transform near-infrared spectroscopy, powder X-ray diffraction (PXRD), and thermal analysis. No molecular interactions were observed in the physical mixture sample. The ground samples showed broad peaks in the PXRD patterns and an exothermic peak at an early temperature. Results: The results suggested that the grinding process transformed MX and SA into a coamorphous phase. The attenuated total reflection - IR spectra exhibited new peaks at 1719 cm^-1 and 1398 cm^-1, and the NH peak disappeared with grinding time. Measurement data of MX and SA ground sample suggested they constructed coamorphous phase. Conclusion: It was indicated by multivariate analysis that the formation of the MX/SA coamorphous system occurred in a two-step process.

BackgroundVarious methods have been reported for improving the water-insoluble drugs in oral administration formulations. Among them, amorphization has been attracting attention and developed as a method for solubilizing API (active pharmaceutical ingredient)s by changing their physicochemical properties. Molecular complexation is also known as a method for solubilizing APIs by synthesizing cocrystals, etc. Co-amorphization, which achieves both molecular complexation and amorphization, is effective and has attracted attention. Thus, co-amorphization has been proven to be an effective approach to solubilization.ObjectiveThis study aims to improve the solubility of lumefantrine, used here as a model compound, through co-amorphization with deoxycholic acid.SignificanceThe physicochemical properties are an important factor in developing pharmaceutical ingredients. Hydrogen-bonded co-amorphization has gained attention as a method to enhance the physicochemical properties of hydrophobic drugs.MethodsThe co-amorphous Lumefantrine-deoxycholic acid system was prepared using a mechanochemical synthesis method based on ball milling. The synthesis process was monitored by powder X-ray diffraction and near-infrared spectroscopy. The products and materials were analyzed by thermal analysis.ResultsSpectroscopic analysis revealed that the two molecules were complexed through intermolecular hydrogen bonding interactions. The produced co-amorphous has no melting point was found by thermal analysis.ConclusionsProcess monitoring also indicated the presence of a metastable crystalline Lumefantrine (LMF) intermediate.