Sharif Digital Repository

In the upcoming research, with the aim of bone tissue engineering and achieving a new structure, a scaffold based on polyhema (PHEMA) and gelatin (Gel), which are biocompatible polymers for bone tissue, was made and evaluated. Also, in order to improve the bioactivity and mechanical properties, bioactive glass alone (BG45S5) or together with strontium (BG-Sr) was used in the scaffold structure. and chemical by conducting FTIR, XRD, SEM, mechanical strength, bioactivity measurement, contact angle, water absorption and degradation tests. Biological investigations were done using mesenchymal stem cells derived from human bone marrow and with the help of MTT evaluations and SEM photography. The... 

In this work, we have used a 3D printer and unidirectional ice-templating technique in conjunction, to fabricate a novel composite scaffold to facilitate local osteochondral defects tissue regeneration with a cell-free approach. Using ice-templating to induce radially-aligned porosity formation in type I bovine collagen is known to expedite host cells' migration into the scaffold which their ECM secretion shifts cellular milieu toward that of its neighboring tissue layer. We used numerical analysis to design and optimize appropriate freeze-casting mold, finding the optimum value for pin height and metal slab depth to be 4mm and 14mm, respectively. Collagen content equivalent to 2%w/v was... 

Growth factors play an important role in tissue repair and regeneration including articular cartilage tissue. Direct injection of growth factor is a common practice in clinics. However, it has been shown that this method is not very effective and, in some cases, induces some side effects. Moreover, incorporation of this valuable signals in systems where they are quickly released and washed out is not effective as well. Thereby the aim of this study was to design and fabricate an efficient system to effectively deliver growth factors for cartilage tissue engineering. The designed system is an injectable, in situ forming hydrogel, based on hyaluronic acid (HA) as a biocompatible and attractive... 

In the last decade, mechanical metamaterials have attracted more attention due to new design principles that combine the concept of hierarchical architecture with material size effects at the micro or nano scale. This strategy shows extraordinary mechanical performance that we use in unknown parts of the material property space, including strength-to-density ratios, extraordinary flexibility, and the ability to absorb energy with brittle components. The aim of this research was to print metamaterial scaffolds from a combination of biocompatible and bioactive to be used as scaffolds in bone tissue engineering. In addition to the biological properties appropriate to the host tissue, the... 

The retina, a photosensitive area in the central nervous system, is delicate and intricate. It is susceptible to degenerative disorders such as age-related macular degeneration (AMD), retinitis pigmentosa (RP), Stargardt disease (SD), and glaucoma. These diseases can lead to severe vision loss and ultimately irreversible blindness by causing destruction or dysfunction of different types of retinal cells. Unfortunately, there are no proven treatment strategies to cure or reverse these degenerative disorders. However, cell transplantation therapies may be an alternative to replace distorted cells and improve an individual's vision. Recent clinical outcomes show that transplanted cells in the... 

Cranioplasty is a surgical procedure for repairing skull defects. This surgery will protect the brain tissue, reduce pain in the lesion site and reduce the psychological burden on the patient. Cranioplasty implants should have distinct characteristics, i.e., high strength for protecting the brain, full coverage of skull defects, resistance to infection, non-expansion with heat, and reasonable price. Titanium implants, bone allografts, hydroxyapatite, and methyl methacrylate are commonly used in this surgery. However, these materials have many disadvantages that limit their use. As a result, biodegradable material and 3D printing technology are the next steps for designing scaffolds according... 

Implant primary stability is a crucial component of implant survival. Primary mechanical stability is correlated with implant type, surgical technique, quantity and quality of bone at the recipient site. Since bone integration (BI) significance has been acknowledged, a variety of techniques have been developed to quicken BI and achieve faster fixation. Studies have shown that material type, and many surface properties, including as surface composition, roughness, topography, and energy, have a significant influence during the early stages of bone integration to the implant. In this work, we did synthesis one-dimensional nanoneedle-like arrays of hydroxyapatite using the injection method... 

3D bioprinting is an additive manufacturing method that facilitates the deposition of the desired cells and biomaterials at any pre-defined location. This technique also enables control over the internal structure and external dimensions of printed constructs. Among various biomaterials used as bioinks, the bioinks derived from decellularized extracellular matrixes (dECMs) have attracted significant attention due to their bioactivity and being a rich source of biochemical cues. Here in this study, the decellularized amnion membrane (dAM) has been selected as the main component of the bioink formulation because of its biocompatibility, low immunogenicity, antibacterial property, abundance,... 

Skin, the largest organ in the body, presents sophisticated functions for maintaining the structural integrity of the entire body. Skin can regulate the temperature of the body, protect the body against microorganisms, have a sensory function, and produce vitamin-D through UV exposure when in direct sunlight.Due to the self-healing property of skin tissue, skin can be repaired by itself. Nevertheless, if extensive skin loss happens, owing to diabetic ulcers or deep burns, skin will not be able to repair the wound by itself. Therefore, it will lose its functions, and the fabrication of a skin equivalent will be necessary. These skin equivalents will cover the wound, regenerate the native... 

Today, due to changes in lifestyle and environmental changes, the incidence of cancer is increasing worldwide. With the advancement of science and technology, humans have always sought ways to improve their quality of life and lifespan. The most common cancer related to bone tissue is osteosarcoma. One of the most effective treatment methods is photodynamic therapy. This method requires a photosensitizer with appropriate optical and biological properties. The ideal photosensitizer should be excited with light in the NIR range and produce ROS or active oxygen species. In this research, oxygen-doped graphitic carbon nitride modified by heterojunction with Mn3O4 was used as a photosensitizer.... 

Cartilage is a connective tissue, whose most important role in the body is to create a surface with a low friction coefficient in order to allow bones to slide on each other without direct contact to transfer loads. Articular cartilage is always under a harsh biomechanical environment and lacks blood, lymphatic and nerve vessels. As a result, it limits the capacity of this tissue to improve and restore itself. According to experimental efforts, cartilage cannot be regenerated spontaneously without the support of healthy subchondral bone. In recent years, the implantation of tissue engineering scaffolds has been considered as an effective strategy for the treatment of osteochondral damage.... 

The main goal of this study is to prepare and investigate stimuli responsive structures that respond to the light and other environmental triggers. Also, investigating their applications in biological fields such as: drug delivery and tissue engineering, in addition to the application of these materials in the field of chemical sensors that show color change with changes in solvent, electric field and metal ions. In the matter of drug delivery, guest-host interactions were used to release anticancer drugs, in such a way that with ultraviolet light irradiation and simultaneously with the formation of the cis isomer, the connections between azobenzene groups and cyclodextrin rings are...