Mohammad Norouzi

Advances in Skin Regeneration: Application of Electrospun Scaffolds

The paucity of cellular and molecular signals essential for normal wound healing makes severe dermatological ulcers stubborn to heal. The novel strategies of skin regenerative treatments are focused on the development of biologically responsive scaffolds accompanied by cells and multiple biomolecules resembling structural and biochemical cues of the natural extracellular matrix (ECM). Electrospun nanofibrous scaffolds provide similar architecture to the ECM leading to enhancement of cell adhesion, proliferation, migration and neo tissue formation. This Review surveys the application of biocompatible natural, synthetic and composite polymers to fabricate electrospun scaffolds as skin substitutes and wound dressings. Furthermore, the application of biomolecules and therapeutic agents in the nanofibrous scaffolds viz growth factors, genes, antibiotics, silver nanoparticles, and natural medicines with the aim of ameliorating cellular behavior, wound healing, and skin regeneration are discussed.

Nanoparticles as Effective Flame Retardants for Natural and Synthetic Textile Polymers: Application, Mechanism, and Optimization

Along with the rising trend of stringent fire safety regulations, demands for reduction in the fire hazard caused by highly combustible materials such as textiles and polymers have become a matter of significant importance. Therefore, numerous attempts have been made to improve the flame retardation of textiles for a variety of applications. The present paper aims to review the recent developments in the flame retardant nanocomposites of natural and synthetic textile polymers. We survey the application of different nanoparticles or a combination of nanoparticles and conventional flame retardants. Furthermore, a comprehensive discussion on mechanisms and optimized conditions of flame retardation and thermal stability is presented.

PLGA/gelatin hybrid nanofibrous scaffolds encapsulating EGF for skin regeneration

The novel strategies of skin regenerative treatment are aimed at the development of biologically responsive scaffolds capable of delivering multiple bioactive agents and cells to the target tissues. In this study, nanofibers of poly(lactic-co-glycolic acid) (PLGA) and gelatin were electrospun and the effect of parameters viz polymer concentration, acid concentration, flow rate and voltage on the morphology of the fibers were investigated. PLGA nanofibers encapsulating epidermal growth factor were also prepared through emulsion electrospinning. The core-sheath structure of the nanofibers was verified by transmission electron microscopy. The hemostatic attributes and the biocompatibility of the scaffolds for human fibroblast cell were scrutinized. Furthermore, gene expression of collagen type I and type III by the cells on the scaffolds was quantified using real-time reverse transcriptase polymerase chain reaction. The results indicated desirable bioactivity and hemostasis of the scaffolds with the capability of encapsulation and controlled release of the protein which can be served as skin tissue engineering scaffolds and wound dressings.

Antibacterial properties and color fastness of silk fabric dyed with turmeric extract

The use of non-toxic and eco-friendly natural dyes on textiles has received much attention due to the increased environmental awareness in order to avoid some hazardous synthetic dyes. In the present study, an eco-friendly approach was developed to impart color and antibacterial properties to silk fabrics dyed with turmeric extract as a non-toxic natural colorant. The natural colorant was extracted from Curcuma Longa rhizome. Copper sulfate, ferrous sulfate and potassium aluminium sulfate were applied in a pre-metallization process as mordanting agents. Antibacterial properties of treated fabrics were evaluated against common pathogenic bacteria, Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). The effects of dye concentration and mordant types on the obtained color hues, antibacterial efficiency and color fastness of the fabrics were investigated. The results indicated that mordanted and dyed fabrics possessed desirable antibacterial properties. Complete antibacterial activity of the treated fabrics was obtained with 3 %owf (on weight of the fabric) copper sulfate. It was also shown that increasing the dye concentration could lead to a more efficient antibacterial activity on the mordanted dyed fabrics. An optimum level of the antibacterial activity was observed in the sample treated with 30 %owf of turmeric. Furthermore, the results of CIE L*, a*, b* values, FTIR, washing, light and rubbing fastnesses of the dyed fabrics were reported. The mordanted dyed silk fabrics exhibited desirable color fastness properties. These studies proved a direct relationship between the degree of antibacterial activity of the fabrics treated with turmeric and the metals ion concentration.

Injectable hydrogel-based drug delivery systems for local cancer therapy

Common chemotherapy is often associated with adverse effects in normal cells and tissues. As an alternative approach, localized chemotherapy can diminish the toxicity of systemic chemotherapy while providing a sustained release of the chemotherapeutics at the target tumor site. Therefore, injectable biodegradable hydrogels as drug delivery systems for chemotherapeutics have become a matter of importance. Here, we review the application of a variety of injectable hydrogel-based drug delivery systems, including thermosensitive, pH-sensitive, photosensitive, dual-sensitive, as well as active targeting hydrogels, for the treatment of different types of cancer. Generally, injectable hydrogel-based drug delivery systems are found to be more efficacious than the conventional systemic chemotherapy in terms of cancer treatment.

Controlled release of rhEGF and rhbFGF from electrospun scaffolds for skin regeneration

Controlled delivery of multiple therapeutic agents can be considered as an effective approach in skin tissue engineering. In this study, recombinant human epidermal growth factor (rhEGF) and recombinant human basic fibroblast growth factor (rhbFGF) encapsulated in PLGA microspheres were loaded in hybrid scaffolds of PLGA and PEO. The scaffolds with various formulations were fabricated through electrospinning in order to maintain dual, individual or different release rate of rhEGF and rhbFGF. Morphological, physical and mechanical properties of the scaffold were investigated. The scaffold possessed uniform morphology with an average diameter of 280 nm for PLGA and 760 nm for PEO nanofibers. Furthermore, the mechanical properties of the scaffolds were shown to be akin to those of human skin. Bioactivity of the scaffolds for human skin fibroblasts was evaluated. The HSF acquired significant proliferation and well-spread morphology on the scaffolds particularly in the case of different release rate of rhEGF and rhbFGF which implies the synergistic effect of the growth factors. Additionally, collagen and elastin gene expression was significantly up-regulated in the HSF seeded on the scaffolds in the case of individual delivery of rhEGF and dual delivery of rhEGF and rhbFGF. In conclusion, the prepared scaffolds as a suitable supportive substrate and multiple growth factor delivery system can find extensive utilization in skin tissue engineering.

EGF-loaded nanofibrous scaffold for skin tissue engineering applications

In this study, nanofibers of poly(lactic-co-glycolic acid) with a core-shell structure encapsulating epidermal growth factor (EGF) were prepared through emulsion electrospinning technique. The morphology and the core-shell structure of the nanofibers were observed by field emission scanning electron microscopy and transmission electron microscopy, respectively. The release profile of EGF indicated a continuous release of the protein over one week. Biocompatibility of the plasma-treated scaffolds was evaluated using MTT assay for human fibroblast cells. The results demonstrated desirable biocompatibility and bioactivity of the scaffolds with the capability of encapsulation and controlled release of EGF which can be utilized in skin tissue engineering applications.

Multifunctional polyester fabric using a multicomponent treatment

In this study, multifunctional polyester fabrics with the features of self-cleaning, water and stain repellency, and thermal stability were prepared utilizing a multicomponent system. To this end, both unmodified and alkaline-hydrolyzed modified fabrics were treated with nano TiO2/citric or maleic acid/sodium hypophosphite/polysiloxane and triethanolamine via a pad-dry-cure method. Surface morphology and color variation of the samples were studied utilizing field emission scanning electron microscopy (FESEM) and CIE-Lab system, respectively. Also, energy-dispersive X-ray (EDX) analysis indicated the content of Ti, P and Si on the surface of fabrics. Thermal stability of the specimen was scrutinized through thermal gravimetric analysis (TGA) and char yield. Both hydrolysis treatment and silicone softener increased the uptake of the nanoparticles. Also, in a comparison between the utilized carboxylic acids, citric acid demonstrated superior features. Generally, the treated fabrics showed desirable self-cleaning and stain repellency with some enhanced thermal stability.

Adaptive line extraction algorithm for SLAM application

This paper proposes a modified split and merge algorithm for line extraction with high accuracy, efficient speed and low complexity. It is robust against measurement noises and demonstrates satisfactory results on different surfaces in determining line boundaries. The method is based on the least square equation to fit a line on a series of uncertain points. Different least square criterion is investigated to choose the best one for line extraction. A novel approach is proposed here to adopt threshold on different surfaces. Although the SLAM is not main goal of this paper, a feature based SLAM is implemented on a mobile rescue robot to observe the proposed line extraction performance, practically.

Recursive line extraction algorithm from 2d laser scanner applied to navigation a mobile robot

This paper presents a novel algorithm for line extraction from 2D laser range finder which has excellent precision to determine of line boundary, while having efficient speed and low complexity. This algorithm is more robust in measurement noise and cluttered data and fit a line to a set of uncertain points via Hough transform and recursive split formalism. In this algorithm first the data from laser is segmented to separate regions by determining start and end points throw Hough transform. After removing noisy or sparse points lines are extracted with a fast recursive split algorithm. Furthermore, it has good real-time capability to integrate the information of laser scanner into the navigation algorithm of the mobile robot and it is implemented on NAJI V rescue robot platform.