Sharif Digital Repository

The design of advanced nanobiomaterials to improve analytical accuracy and therapeutic efficacy has become an important prerequisite for the development of innovative nanomedicines. Recently, phospholipid nanobiomaterials including 2-methacryloyloxyethyl phosphorylcholine (MPC) have attracted great attention with remarkable characteristics such as resistance to nonspecific protein adsorption and cell adhesion for various biomedical applications. Despite many recent reports, there is a lack of comprehensive review on the phospholipid nanobiomaterials from synthesis to diagnostic and therapeutic applications. Here, we review the synthesis and characterization of phospholipid nanobiomaterials... 

In this paper an analytical approach to study the effect of the substrate physical properties on the kinetics of adhesion and motility behavior of cells is presented. Cell adhesion is mediated by the binding of cell wall receptors and substrate's complementary ligands, and tight adhesion is accomplished by the recruitment of the cell wall binders to the adhesion zone. The binders' movement is modeled as their axisymmetric diffusion in the fluid-like cell membrane. In order to preserve the thermodynamic consistency, the energy balance for the cell-substrate interaction is imposed on the diffusion equation. Solving the axisymmetric diffusion-energy balance coupled equations, it turns out that... 

The present study demonstrates HEMA-grafted nanodiamond (ND-HEMA)/acrylate-terminated polyurethane-acrylate diluents (APUA) composites as promising materials for bone implant applications. Neat APUA and APUA composites containing ND-HEMA at different loadings up to 2 wt% were prepared by an in situ polymerization method. Morphological analysis demonstrated that ND-HEMAs were actually in the form of tightly bound aggregates which led to formation of big agglomerates at a concentration of 2 wt%. It was also suggested that ND-HEMAs were preferentially localized in the continuous soft domain of APUA; however it interacted by both soft and hard domains. Moreover, ND-HEMAs caused considerable... 

Electrospinning of biopolymers has gained significant interest for the fabrication of fibrous mats for potential applications in tissue engineering, particularly for wound dressing and skin regeneration. In this study, for the first time, we report successful electrospinning of chitosan-based biopolymers containing bacterial cellulous (33 wt %) and medical grade nanodiamonds (MND) (3 nm; up to 3 wt %). Morphological studies by scanning electron microscopy showed that long and uniform fibers with controllable diameters from 80 to 170 nm were prepared. Introducing diamond nanoparticles facilitated the electrospinning process with a decrease in the size of fibers. Fourier transform infrared... 

Background: Nutrigenomic has revolutionized our understanding of nutrition. As plants make up a noticeable part of our diet, in the present study we chose microRNAs of edible plants and investigated if they can perfectly match human genes, indicating potential regulatory functionalities. Methods: miRNAs were obtained using the PNRD database. Edible plants were separated and microRNAs in common in at least four of them entered our analysis. Using vmatchPattern, these 64 miRNAs went through four steps of refinement to improve target prediction: Alignment with the whole genome (2581 results), filtered for those in gene regions (1371 results), filtered for exon regions (66 results) and finally... 

Design and development of biodegradable scaffolds with highly uniform and controlled internal structure that stimulate tissue regeneration are the focus of many studies. The aim of this work is to apply a modified three-dimensional (3D) printing process to fabricate polymer-matrix composites with controlled internal architecture. Computationally-designed plaster molds with various pore sizes in the range of 300-800. μm were prepared by employing 3D printing of a water-based binder. The molds were converted to ε-polycaprolactone (PCL) and PCL/bioactive glass (BG) composite scaffolds by solvent casting and freeze drying methods. Optical and electron microscopy studies revealed that the pore... 

The effects of intermediate nickel layer on seal strength and chemical compatibility of seal glass and interconnect materials for solid oxide fuel cells (SOFCs) were investigated. Two types of samples (metal/glass/metal sandwiches and glass coated metals) were prepared with the sheet of AISI 430 (nickel plated and uncoated) and slurry of compliant silicate sealing glass (SCN-1). The joined and coated samples were heated at 850 °C for different time durations (0.5-100 h). Tensile and impact tests were performed and SEM micrographs were used to analyze the glass/metal interaction. The results indicate that nickel plated AISI 430 shows higher adhesion strength at short durations of heating due... 

Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples,... 

The addition of alloying elements to magnesium leads to microstructural refinement and improves its properties. However, this strategy is accompanied by another concurrent phenomenon − that is − intergranular segregation and the formation of secondary phases in grain boundaries, deteriorating the properties. In this work, the efficacy of two main factors on modifying the mechanical properties and corrosion behavior of Mg-4Zn-1Al-0.2Ca alloy was investigated separately: 1) dissolution of secondary phases; and 2) grain refinement. Based on the results, heat treatment of the as-cast alloy can increase the UTS from 174.4 to 213.2 MPa, decrease the corrosion current density from 81 to 49 μA/cm2,... 

Due to the avascular nature of articular cartilage, damaged tissue has little capacity for spontaneous healing. Three-dimensional scaffolds have potential for use in tissue engineering approach for cartilage repair. In this study, bovine cartilage tissue was decellularized and chemically crosslinked hybrid chitosan/extracellular matrix (ECM) scaffolds were fabricated with different ECM weight ratios by simple freeze drying method. Various properties of chitosan/ECM scaffolds such as microstructure, mechanical strength, swelling ratio, and biodegradability rate were investigated to confirm improved structural and biological characteristics of chitosan scaffolds in the presence of ECM. The... 

There are numerous functions for laser in modern implant dentistry including surface treatment, surface coating, and implant manufacturing. As laser application may potentially improve osseointegration of dental implants, we systematically reviewed the literature for in vitro biological responses to laser-modified or processed titanium dental implants. The literature was searched in PubMed, ISI Web, and Scopus, using keywords “titanium dental implants,” “laser,” “biocompatibility,” and their synonyms. After screening the 136 references obtained, 28 articles met the inclusion criteria. We found that Nd:YAG laser was the most commonly used lasers in the treatment or processing of titanium... 

Nanofibrous structures that mimic the native extracellular matrix and promote cell adhesion have attracted considerable interest for biomedical applications. In this study, GO-modified nanofibrous biopolymers (GO) were prepared by electrospinning blended solutions of chitosan (80 vol%), polyvinyl pyrrolidone (15 vol%), polyethylene oxide (5 vol%) containing GO nanosheets (0–2 wt%). It is shown that GO nanosheets significantly change the conductivity and viscosity of highly concentrated chitosan solutions, so that ultrafine and uniform fibers with an average diameter of 60 nm are spinnable. The GO-reinforced nanofibers with controlled pore structure exhibit enhanced elastic modulus and... 

The fabrication of a suitable scaffold material is one of the major challenges for bone tissue engineering. Poly(lactic acid) (PLA) is one of the most favorable matrix materials in bone tissue engineering owing to its biocompatibility and biodegradability. However, PLA suffers from some shortcomings including low degradation rate, low cell adhesion caused by its hydrophobic property, and inflammatory reactions in vivo due to its degradation product, lactic acid. Therefore, the incorporation of bioactive reinforcements is considered as a powerful method to improve the properties of PLA. This review presents a comprehensive study on recent advances in the synthesis of PLA-based biocomposites... 

In order to fabricate nanofiber scaffold for bone tissue engineering, electrospinning technique was employed. This technique produces nanofiberous scaffold supporting cell adhesion, migration, and proliferation. Here, we developed a novel conductive scaffold from poly-caprolactone, gelatin, and poly aniline/graphene nanoparticles. In this study, co-electrospinning was utilized to fabricate composite electrospun scaffold. The effect of polyaniline/graphene (PAG) nanoparticles on the mechanical properties and electrical conductivity of this hybrid scaffold was investigated. The result showed that PAG nanoparticles enbance both mechanical properties and electrical conductivity of the scaffolds.... 

Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1... 

High rates of mortality and morbidity stemming from cardiovascular diseases unveil extreme limitations in current therapies despite enormous advances in medical and pharmaceutical sciences. Following myocardial infarction (MI), parts of myocardium undergo irreversible remodeling and is substituted by a scar tissue which eventually leads to heart failure (HF). To address this issue, cardiac patches have been utilized to initiate myocardial regeneration. In this study, a porous cardiac patch is fabricated using a mixture of decellularized myocardium extracellular matrix (ECM) and chitosan (CS). Results of rheological measurements, SEM, biodegradation test, and MTT assay showed that the... 

Polycaprolactone (PCL) is a bioresorbable and biocompatible polymer that has been widely used in long-term implants and controlled drug release applications. However, when it comes to tissue engineering, PCL suffers from some shortcomings such as slow degradation rate, poor mechanical properties, and low cell adhesion. The incorporation of calcium phosphate-based ceramics and bioactive glasses into PCL has yielded a class of hybrid biomaterials with remarkably improved mechanical properties, controllable degradation rates, and enhanced bioactivity that are suitable for bone tissue engineering. This review presents a comprehensive study on recent advances in the fabrication and properties of... 

Biodegradable polymer/bioceramic nanocomposites are osteoconductive and can accelerate healing of bone tissue. In this research, silk fibroin (SF)/titanium dioxide (TiO2) nanocomposites were synthesized using different concentrations of TiO2 nanoparticles (0, 5, 10, 15 and 20 wt%). The SF/TiO2 nanocomposites were studied in terms of bioactivity and biocompatibility. The in vitro assessment of osteoblasts compatibility indicated that SF inclusion rendered nanocomposite biocompatible whereas presence of TiO2 nanoparticles allowed the cells to adhere and grow on nanocomposite surface and enhanced the bioactivity of the composite. © 2017, Taiwanese Society of Biomedical Engineering