A modular approach to 3D-printed bilayer composite scaffolds for osteochondral tissue engineering.

Prolonged osteochondral tissue engineering damage can result in osteoarthritis and decreased quality of life. Multiphasic scaffolds, where different layers model different microenvironments, are a promising treatment approach, yet stable joining between layers during fabrication remains challenging. To overcome this problem, in this study, a bilayer scaffold for osteochondral tissue regeneration was fabricated using 3D printing technology which containing a layer of PCL/hydroxyapatite (HA) nanoparticles and another layer of PCL/gelatin with various concentrations of fibrin (10, 20 and 30 wt.%). These printed scaffolds were evaluated with SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) and mechanical properties. The results showed that the porous scaffolds fabricated with pore size of 210-255 µm. Following, the ductility increased with the further addition of fibrin in bilayer composites which showed these composites scaffolds are suitable for the cartilage part of osteochondral. Also, the contact angle results demonstrated the incorporation of fibrin in bilayer scaffolds based on PCL matrix, can lead to a decrease in contact angle and result in the improvement of hydrophilicity that confirmed by increasing the degradation rate of scaffolds containing further fibrin percentage. The bioactivity study of bilayer scaffolds indicated that both fibrin and hydroxyapatite can significantly improve the cell attachment on fabricated scaffolds. The MTT assay, DAPI and Alizarin red tests of bilayer composite scaffolds showed that samples containing 30% fibrin have the more biocompatibility than that of samples with 10 and 20% fibrin which indicated the potential of this bilayer scaffold for osteochondral tissue regeneration.

Progress in bioprinting technology for tissue regeneration.

In recent years, due to the increase in diseases that require organ/tissue transplantation and the limited donor, on the other hand, patients have lost hope of recovery and organ transplantation. Regenerative medicine is one of the new sciences that promises a bright future for these patients by providing solutions to repair, improve function, and replace tissue. One of the technologies used in regenerative medicine is three-dimensional (3D) bioprinters. Bioprinting is a new strategy that is the basis for starting a global revolution in the field of medical sciences and has attracted much attention. 3D bioprinters use a combination of advanced biology and cell science, computer science, and materials science to create complex bio-hybrid structures for various applications. The capacity to use this technology can be demonstrated in regenerative medicine to make various connective tissues, such as skin, cartilage, and bone. One of the essential parts of a 3D bioprinter is the bio-ink. Bio-ink is a combination of biologically active molecules, cells, and biomaterials that make the printed product. In this review, we examine the main bioprinting strategies, such as inkjet printing, laser, and extrusion-based bioprinting, as well as some of their applications.

Preparation and characterization of curcumin-loaded polymeric nanomicelles to interference with amyloidogenesis through glycation method.

Amyloid fibrils, including ß-amyloid (Aß) fibrils, are protein aggregates that form under certain conditions, associated with neurodegeneration that interfere with neural synaptic transmission resulting in some neural disorders, such as Alzheimer's disease. The aim of this study is to inhibit amyloidogenesis by using preparatory polymeric nanomicelles as therapeutic agents and also as nanocarriers for curcumin to target Aß fibrils through the glycation method of bovine serum albumin (BSA) in the presence of phosphate-buffered saline. Polymeric nanomicelles were prepared from phosphatidylethanolamine-distearoyl methoxypolyethylene glycol conjugates in the presence and absence of curcumin and then the morphological and structural characteristics of the nanomicelles were characterized in detail. Following the preparation of unloaded and curcumin-loaded nanomicelles with the desired size and properties, their effects on BSA glycation/fibrillation process were investigated. The samples were analyzed by thioflavin T (ThT) fluorescence and advanced glycation end (AGE) products autofluorescence measurements. The results showed that ThT fluorescence related to the formation of ß-sheets and AGE autofluorescence (associated with AGE production) decreased in the presence of curcumin-loaded nanomicelles more than other samples. In conclusion, the promising effect of curcumin-loaded nanomicelles on inhibition of amyloidogenesis through glycation process due to curcumin release and thus their ability to prevent the formation and accumulation of amyloid fibrils and so to suppress the Alzheimer's disease progression has been proven and can go for further investigations.

Poly(lactic-co-glycolic acid)(PLGA)/TiO2 nanotube bioactive composite as a novel scaffold for bone tissue engineering: In vitro and in vivo studies.

The aim of this study was to synthesize and characterize novel three-dimensional porous scaffolds made of poly (lactic-co-glycolic acid)/TiO2 nanotube (TNT) composite microspheres for bone tissue engineering applications. The incorporation of TNT greatly increases mechanical properties of PLGA/TNT microsphere-sintered scaffold. The experimental results exhibit that the PLGA/0.5 wt% TNT scaffold sintered at 100 °C for 3 h showed the best mechanical properties and a proper pore structure for tissue engineering. Biodegradation test ascertained that the weight of both PLGA and PLGA/PLGA/0.5 wt% TiO2 nanotube composites slightly reduced during the first 4 weeks following immersion in SBF solution. Moreover, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and alkaline phosphatase activity (ALP activity) results represent increased cell viability for PLGA/0.5%TNT composite scaffold in comparison to the control group. In vivo studies show the amount of bone formation for PLGA/TNT was approximately twice of pure PLGA. Vivid histologic images of the newly generated bone on the implants further supported our test results. Eventually, a mathematical model showed that both PLGA and PLGA/TNT scaffolds' mechanical properties follow an exponential trend with time as their degradation occurs. By a three-dimensional finite element model, a more monotonous distribution of stress was present in the scaffold due to the presence of TNT with a reduction in maximum stress on bone.

Thermoresponsive and Supramolecular Polymers: Interesting Biomaterials for Drug Delivery.

How to use and deliver drugs to diseased and damaged areas has been one of the main concerns of pharmacologists and doctors for a long time. With the efforts of researchers, the advancement of technology, and the involvement of engineering in the health field, diverse and promising approaches have been studied and used to achieve this goal. A better understanding of biomaterials and the ability of production equipment led researchers to offer new drug delivery systems to the world. In recent decades, responsive polymers (exclusively to temperature and pH) and supramolecular polymers have received much attention due to their unique capabilities. Although this field of research still needs to be scrutinized and studied more, their recognition, examination, and use as drug delivery systems is a start for a promising future. This review study, focusing on temperature-responsive and supramolecular biomaterials and their application as drug delivery systems, deals with their structure, properties, and role in the noninvasive and effective delivery of medicinal agents.

Enhancing Mechanical and Biological Properties of Zinc Phosphate Dental Cement with Akermanite and Hardystonite Nanoparticles: A Synthesis and Characterization Study.

This study investigates the potential of incorporating akermanite and hardystonite nanoparticles (NPs) into commercially available zinc phosphate cement. Akermanite and hardystonite NPs were synthesized through a mechanical route and characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The NPs were then added to the cement at a concentration of 5 wt%, and the physical and biological properties of the resulting composite were evaluated. The results showed that the incorporation of NPs led to a significant reduction in porosity (from 12.4% to 5.6%) and a notable improvement in compressive strength (from 90 to 120 MPa) compared to the control group. MTT assay revealed that the cement containing NPs exhibited no significant toxicity and even promoted cell growth and proliferation. Specifically, cell viability increased by 15%, and cell proliferation rate increased by 20% compared to the control group. These findings suggest that the designed cement has suitable mechanical and biological properties, making it a promising material for dental and orthopedic applications.