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The characteristics of a scaffold that is the basic component of tissue engineering are considerably influenced by the fiber diameter of the fibrous scaffolds. Since the significant effect of the fiber diameter on the scaffold properties, many researchers have focused on estimating the fiber diameter based on the electrospinning parameters. With similar motivation, in this paper, a new and simple closed-form expression, which can help researchers in fabricating the electrospun poly (ԑ-caprolactone) (PCL) scaffold with desired fiber diameter, is presented. In order to construct the expression proposed, an experimental study has been performed to obtain the data set, in which 25 experimental data including average fiber diameter (AFD) values dependent on different combinations of parameters such as voltage, solution concentration, tip to collector (TTC) distance, and flow rate. Then, an expression has been constructed that is used to estimate the AFD of the electrospun PCL, and the coefficients of the expression were determined by using the artificial bee colony (ABC) algorithm. In order to validate the estimation ability of the expression, the metrics such as mean absolute error (MAE) and mean absolute percentage error (MAPE) have been used, and the optimization and test errors were respectively obtained as 3.30% and 1.27% in terms of MAPE. In addition, the results obtained were compared with those reported in the literature. Results show that our new expression can be successfully used to estimate the AFD of electrospun PCL prior to the electrospinning process. Thus, the number of test repetitions could be reduced by using the expression proposed, and time, cost, and labor could be saved in this way. This study contributes to the literature because there have been only a limited number of studies that focus on estimating the AFD of PCL nanofiber despite many studies about various polymers.

Macrophages play a vital role in rejection of the implant materials by producing pro-inflammatory TNF and IL6 cytokines. They are also important for the normal function of the immune system to fight against infections. Therefore, characterizing the immunotoxicity on this cell type will be informative for the medical use of the biocompatible materials. Chitosan-based materials have been widely considered as biocompatible and safe. They have been suggested for the bone implants. Studies suggest that depending on the setup and chitosan functionalization, the immune system may react differentially to the chitosan-based materials. In this study, we characterized the immunocompatibility of injectable chitosan cryogel microspheres on mammalian macrophages by measuring their effect on cell viability and these cells’ ability to produce pro-inflammatory cytokines in the absence and presence of LPS, as a stimulant. Different sizes of microspheres were used to examine the effect of the size on their plausible effects. Our results suggest that independent of their size, chitosan cryogel microspheres were immunocompatible. They did not influence the cell viability and pro-inflammatory cytokine production by LPS-induced macrophages. Moreover, these materials lacked immunostimulatory activity as well, which means they would not activate the macrophages in the absence of any stimulant after their direct interaction with these cells. These properties are advantageous for their possible utilization in the medical fields as minimally invasive materials due to their injectable properties.

In this study, a herbal infused oil (Hypericum perforatum, HP) incorporated chitosan (CS) cryogel as a wound dressing material was produced in order to be used in wound healing process. The main strategy is to combine the traditional perspective of using medicinal oils with polymeric scaffolds manufactured by an engineering approach to fabricate a potential tissue engineering product that provides both new tissue formation and wound healing. The scaffolds manufactured by cryogelation were soft, spongy, highly porous, physically stable, elastic and could be easily cut in any desired shape. Physicochemical, mechanical and morphological analyzes were used to characterize the produced cryogels. Young modulus of the plain chitosan cryogel was about 21 kPa whereas it increased with increasing HP oil content and became 61 kPa for 20% HP oil ratio. Further, the antimicrobial studies, antioxidant and DNA cleavage effects were investigated. Samples including the highest ratio of oil (CS4) showed the highest DPPH scavenging activity as 69.9%. In addition, 20% HP oil loaded chitosan cryogel demonstrated single strain DNA cleavage activitiy at 500 μg/mL concentration. Antimicrobial studies were applied against seven strains. The lowest activities were obtained against E. hirae and B. cereus, the highest against E. coli and L. pneumophila. This study concluded that the newly developed HP oil loaded chitosan cryogel scaffolds with unique antimicrobial and antioxidant properties are promising candidates to be used in tissue engineering applications as wound dressing for exudative and long-term healing wounds.

Fabricating scaffolds with biomimetic architectures is an important step toward engineering functional tissues. Electrospinning is a popular approach for creating nanofibrous substrates in which th...

The present study involves the fabrication of CH and CH-Ag hydrogel beads and the investigation of the antimicrobial properties. The beads were fabricated using a simple coacervation method. The su...

Herein, we synthesized poly(vinyl alcohol) (PVA) decorated chitosan grafted poly(NIPAM-co-AAc) hydrogels through free-radical copolymerization. Increased PVA concentration revealed enhancement of t...

Pectin is a type of anionic polysaccharide naturally found in a number of fruits and vegetables. Although pectin is widely used for food industry, its biomedical applications such as wound dressing, drug delivery and cancer targeting have also been investigated. In our study, we combined extracted pectin (from albedo of lemon peels) with chitosan (as a natural polymer) to synthesize chitosan/pectin cryogels. The extracted pectin was subjected to qualitative and quantitative analyses. Chitosan/pectin spongy supermacroporous cryogels were produced by cryogelation method at different combinations (100:0, 80:20, 60:40 and 40:60, w/w). Polyelectrolyte interactions between pectin and chitosan and crosslinking of chitosan with glutaraldehyde were verified by using FTIR. The porosity, swelling ratio, degradation behaviors and mechanical properties of cryogels were determined. SEM analysis demonstrated the pore morphology and average pore diameters of cryogels. After all analysis, 40:60 chitosan/pectin cryogel was selected for cytotoxicity studies. Glioblastoma (U-87 MG) cell line was used to evaluate the in vitro cytotoxicity of scaffolds. MTT assay and SEM analyses demonstrated the scaffolds were nontoxic, and supported cell attachment and viability.

Difficulty in the clinical practice of stem cell therapy is often experienced in achieving desired target tissue cell differentiation and migration of stem cells to other tissue compartments where they are destroyed or die. This study was performed to evaluate if mesenchymal stem cells (MSCs) may differentiate into desired cell types when injected after combined with an injectable cryogel scaffold and to investigate if this scaffold may help in preventing cells from passing into different tissue compartments. MSCs were obtained from fat tissue of the rabbits as autografts and nuclei and cytoplasms of these cells were labeled with BrdU and PKH26. In Group 1, only-scaffold; in Group 2, only-MSCs; and in Group 3, combined stem cell/scaffold were injected to the right malar area of the rabbits. At postoperative 3 weeks, volumes of the injected areas were calculated by computer-tomography scans and histopathological evaluation was performed. The increase in the volume of the right malar areas was more in Group 3. In histopathological evaluation, chitosan cryogel microspheres were observed microscopically within the tissue and the scaffold was only partially degraded. Normal tissue form was seen in Group 2. Cells differentiated morphologically into fat cells were detected in Groups 2 and 3. Injectable chitosan cryogel microspheres were used in vivo for the first time in this study. As it was demonstrated to be useful in carrying MSCs to the reconstructed area, help cell differentiation to desired cells and prevent migration to other tissue compartments, it may be used for reconstructive purposes in the future.

Due to complex nature of twenty-first century battlefield, soldiers must perform multiple tasks to protect nations while maintaining their own safety. Advances in technological innovations are critical to support such functionalities to enhance safety and security. Using nexus of electrospinning and additive processing, we present how recent developments can be used to produce new generation of protective fabrics with integrative force protection, sensing/detection of chemical, biological, radiological, nuclear, and high yield explosives (CBRNE), and biomedical functionalities. Although electrospinning has been in use for some time, the special blends and configurations of nanofibers, as described here, offer several unique characteristics that render textile lightweight yet effective against impact, breathable yet offers protection against chemical and biological agents, and provides effective protection for various specific applications. Thus, the newly developed composite materials gained various features such as flame retardancy, UV protection, pollutant capturing, antibacterial property, decontamination, detoxification, and self-cleaning ability as well as providing donning comfort. These properties can be achieved by incorporating functional agents with specific ligands or molecules into the fibers. A diverse set of morphologies can also be produced by regulating the operating conditions and needle configurations. The additive processing offers a scaffold configuration for specific applications and hence a nexus of the two processes are used in various applications due to their extraordinary physico-chemical features in reduced dimensions.

In this study, an in-situ chemical reduction approach was used to immobilize silver nanoparticles (AgNPs) on injectable chitosan cryogel microspheres. The surface morphology and the effect of AgNPs...

Dye effluents of wastewater of textile and other industries, particularly reactive azo dyes, are serious safety and health problem for the environment and living organisms. This study demonstrates the results of the removal of Procion Red MX-5B (PR MX-5B) from an aqueous solution by using cryogels prepared from natural polymers. A polymeric cryogel based on chitosan and gelatin was synthesized by cryogelation via crosslinking reaction of polymers at cryogenic conditions. Chitosan-gelatin cryogel (CH-GEL) crosslinked with glutaraldehyde was utilized for adsorption of PR MX-5B dye from aqueous solutions. The synthesized cryogel was chemically characterized by using Fourier Transform Infrared Spectroscopy (FTIR). The scanning electron microscopy (SEM) was used for the morphological characterization of cryogels. The fabricated cryogel has a highly interconnected and open macroporous structure. The water uptake properties of the cryogel in distilled water was determined. The parameters affecting the adsorption of dyes, such as pH of dye solution, initial concentration of dye and adsorbent dosage were studied. The maximum adsorption capacity of the CH-GEL cryogel for the removal of PR MX-5B in 50 mg/L of dye solution was 64.56 mg/g. The macroporous CH-GEL cryogels, due to their highly interconnected porous structure, can be effectively used as adsorbents to remove the PR MX-5B reactive dye from wastewater sources. As a result, an eco-friendly biosorbent was fabricated for the removal of toxic dye molecules from aqueous solutions.

Recent growth in industrialization and globalization has resulted in excessive water-stress in our water resources. Pollution in water pollution comes from anthropogenic activities and level of pollution and emerging contaminants have become an immediate challenge to the living organisms. Water resources now consist of metals, inorganics, pathogens, returned pharmaceuticals, dyes, pesticides, toxic industrial chemicals, organic pollutants, and other new and emerging contaminants, which need to be sufficiently treated before disposal back into the natural body of water. Several membrane-based water purification technologies have attracted attention and interest in the last decade. One of the methodologies that is applied commonly is by using membranes. Among various membranes, electrospun nanofibrous membranes offer unique properties, such as high and tunable porosity, high surface area, tunability in the composition and structure, functionalization ability and good mechanical behaviour, to be used in water purification compared to conventional membranes. This chapter reviews the past achievements and recent research trends of electrospun nanofibrous materials employed for water remediation.

Cryogels are polymeric matrices with 3D architecture fabricated by cryotropic gelation at subzero temperatures via co-polymerization of monomers or crosslinking of linear polymers. The main characteristic feature of these materials that distinguishes them from other gels is their continuous and highly porous structure resulting from cryopolymerization that occurs in a two-phase environment. Highly porous polymeric cryogels can be produced in various shapes and sizes. There are many application areas of cryogels due to their individual properties. The applications of supermacroporous cryogels in the biomedical and biotechnological fields have been well reported in the literature. However, studies on the use of these unique gels in wastewater treatment as a solid adsorbent have started to attract attention in the last few years. The cryogels are suitable adsorbents for the removal of non-degradable organic and synthetic toxic compounds in wastewater. In addition, these cryogel matrices have superior properties including high surface area, high porosity, spongy structure, and physical stability during swelling conditions compared to other gel materials available. This chapter highlights the details of cryotropic gelation, process parameters effective on characteristics of cryogels and utilization areas of these materials specifically in water purification applications.

Electrospinning is a well-known technique that produces polymeric nanofibers using an electrically driven jet of a polymer solution. Due to unique properties such as high surface area, porosity, tensile strength and extensibility of the materials produced by electrospinning, several applications of them in protective clothing, space technology, filtration and tissue engineering have been proposed and investigated. In this study; we prepared gelatin nanofibrous scaffolds by using the electrospinning method for tissue engineering applications. The beads-free, smooth and uniform gelatin nanofibers were successfully fabricated. The blend solutions at different weight ratios were prepared by dissolving gelatin in a solvent mixture containing formic acid, dichloromethane and acetic acid. The fabricated nanofibers were chemically crosslinked by glutaraldehyde vapor. The crosslinked nanofibrous scaffolds were characterized by chemical and morphological analysis. The morphology and size distribution curves of nanofibers were determined by Scanning electron microscopy (SEM). The chemical structure of nanofibers was investigated by Fourier transform infrared spectroscopy (FTIR) analysis. The strategy based on electrospinning of gelatin nanofibers can be used to develop new biomimetic materials for tissue engineering applications.

The research goal of this study is to produce suitable scaffolds for tissue engineering applications. Different ratios of polyvinyl alcohol (PVA)/starch (90:10, 70:30, 50:50) and crosslinking metho...

In this study, we developed a novel strategy, through which cartilage tissue pieces were placed in a sheep cartilage defect model and covered with a collagenase incorporated cryogel scaffold (in vi...

Electrospinning is significantly one of the simple and versatile methods for producing micro- and nanofibrous scaffolds. Its assembly can be modified in different ways to combine material properties with different morphological structures for biomedical applications. In this process, collector design plays an important role to determine the nanofiber orientation in electrospun nanoweb. In this work, 3D patterned scaffolds were produced by electrospinning of polyamide-66 solution on different 3D collectors that have been obtained. The aim of this work is to investigate the attachment of the chondrocyte cells on the prepared electrospun scaffolds that have different types of nanofiber orientations that could be used in tissue engineering applications.

Treatment of tissue defects involves invasive processes such as implanting the tissue engineered scaffold to the defected area. Injectable scaffolds are increasingly being developed to achieve tissue regeneration in a less invasive manner. In this study, injectable chitosan cryogels in the form of microspheres were synthesized combining the water in oil emulsification method with the crosslinking of microspheres during cryogelation. The effects of polymer ratio, crosslinker concentration, cryogelation temperature, and stirring speed on the resulting cryogels’ chemistry, pore morphology, microsphere size, swelling ratio, degree of crosslinking, and degradation rate were examined for a possible noninvasive tissue engineering application. Microspheres with optimized properties were developed with an average pore and particle size of 5.50 ± 0.63 and 220.11 ± 25.58 µm at a chitosan ratio of 1%, glutaraldehyde concentration of 3%, reaction temperature of −16°C, and stirring rate of 1,000 rpm.

The primary task of protective clothing is to maximize the user’s survival, sustainability and effectiveness against cold, heat, fire, ballistic, biological, radiological, nuclear and chemical agents. The protective textiles made of many different fabric materials have been widely used to provide effective protection for various specific applications. With the recent and ongoing advancements in nanotechnology, it is desirable that protective textiles have multifunctional properties. Thus, the newly developed composite materials gained various features such as flame retardancy, UV protection, pollutant capturing, antibacterial property, decontamination, detoxification and self-cleaning ability as well as providing wearing comfort. These properties can be achieved by incorporating functional agents (specific functional ligands or molecules, nanoparticles and drugs) into fabricated materials. Therefore, a new generation of protective fabrics has been produced in recent years. Electrospun textile materials are suitable for use as new protective clothing due to their easy production method, breathable, lightweight, comfortable and functionalizable properties. The electrospun membranes can be fabricated with diverse morphologies (core-shell, side-by-side, multilayer, hollow interior and with high porosity) by regulating the operating conditions and modifying the needle device. Electrospun nanofibers can be used in various application areas including filtration, sensing, wastewater treatment, biomedicine and protective textiles due to their extraordinary physicochemical features at nano level. This chapter aims to review recent advances of the electrospinning technique and the use of multi-functional electrospun materials for protection against chemical and biological agents.

In the new and transformative era, our surrounding environments are increasingly connected through exponential growth of cyber-physical systems (CPS) and interactive intelligent technologies. One such example includes technological innovations in Unmanned Aerial Surveillance Platforms, also known as drones, for applications such as surveillance, real-time monitoring, emergency augmentation for actionable response, security and enabler of connected communities to bring about new levels of opportunity and growth, safety and security, health and wellness, thus improving the overall quality of life. Based on our previous experiences, we present a modality of smart and connected sensors platforms that have a great potential to provide enhanced situational awareness for safety and security. The objective of this investigation is to develop a mobile Unmanned Aerial Surveillance Platform (UASP) capable of monitoring in real-time, capturing, synthesizing and analyzing the information and allowing communication with ground-based systems for actionable response. Several commercial off the shelf (COTS) instruments such as hyperspectral imagers, Light Detection and Ranging (LIDAR), Laser-induced Breakdown Spectroscopy (LIBS) and Biometrics Facial Recognitions systems are discussed along with some innovative platforms that are still in experimental stages and can potentially serve as payload to the unmanned aerial vehicle (UAV) sensor platforms. The new system under development has an airborne component to capture relevant information from a Domain of Interest (DoI). This paper summarizes the capabilities of UASP along with several potential applications and potential risk scenarios of such smart and connected by internet of everything (IOET) systems.

Tissue engineering aims regenerating damaged tissues by using porous scaffolds, cells and bioactive agents. The scaffolds are produced from a variety of natural and synthetic polymers. Collagen is a natural polymer widely used for scaffold production in the late years because of its being the most important component of the connective tissue and biocompatibility. Cryogelation is a relatively simple technique compared to other scaffold production methods, which enables to produce interconnected porous matrices from the frozen reaction mixtures of polymers or monomeric precursors. Considering these, collagen was isolated in this study from fish skin which is a non-commercial waste material, and scaffolds were produced from this collagen by cryogelation method. By SEM analysis, porous structure of collagen, and by UV-Vis analysis protein structure was proven, and by Zeta potential iso-electrical point of the protein was determined, and, Amit A, Amit B, Amit I, Amit II and Amit III characteristical peaks were demonstrated by FTIR analysis. The collagen isolation yield was, 14.53% for acid soluble collagen and 2.42% for pepcin soluble collagen. Scaffolds were produced by crosslinking isolated acid soluble collagen with glutaraldehyde at cryogenic conditions. With FTIR analysis, C=N bond belonging to gluteraldehyde reaction with collagen was found to be at 1655 cm-1. It was demonstrated by SEM analysis that collagen and glutaraldeyhde concentration had significant effects on the pore morphology, diameter and wall thickness of the cryogels, which in turned changed the swelling ratio and degradation profiles of the matrices. In this study, synthesis and characterization results of a fish skin isolated collagen cryogel scaffold that may be potentially used in the regeneration of damaged tissues are presented.

Bolgen, Nimet/0000-0003-3162-0803; Meydanli, E. Elif Guzel/0000-0001-9072-3322; Cetinkaya, Duygu Uckan/0000-0003-3593-6493; KILIC, Emine/0000-0003-2984-7638; Weeks, Jason/0000-0001-5537-6927 WOS: 000463175200003 PubMed: 30942631 Repair of cranial bone defects is an important problem in the clinical area. The use of scaffolds combined with stem cells has become a focus in the reconstruction of critical-sized bone defects. Electrospinning became a very attracting method in the preparation of tissue engineering scaffolds in the last decade, due to the unique nanofibrous structure of the electrospun matrices. However, they have a limitation for three dimensional (3D) applications, due to their two-dimensional structure and pore size which is smaller than a cellular diameter which cannot allow cell migration within the structure. In this study, electrospun poly(epsilon-caprolactone) (PCL) membranes were spirally wounded to prepare 3D matrices composed of nanofibers and macrochannels. Mesenchymal stromal/stem cells were injected inside the scaffolds after the constructs were implanted in the cranial bone defects in rats. New bone formation, vascularisation and intramembranous ossification of the critical size calvarial defect were accelerated by using mesenchymal stem cells combined 3D spiral-wounded electrospun matrices. Turkish Academy of SciencesTurkish Academy of Sciences This study was performed in the context of the EU-FP6-NoE Expertissues Project. Erhan Piskin is supported by Turkish Academy of Sciences as a Honorary Member. This study was a part of PhD thesis of smail Alper isoglu. The thesis was supervised by Erhan Piskin.

Chitosan is a natural polymer synthesized from the chitin of crab, lobster shells, fungal mycelia and shrimp. It has been used for biomedical applications in many different structures including thin film, nanofibrous membrane, sponge, microsphere, hydrogel and cryogel because of its non-toxicity, biodegradability, biocompatibility and antibacterial properties. Cryogelation technique is based on the crosslinking of polymers or crosslinking polymerization of monomers in the presence of crosslinking agents at temperatures below zero. On the other hand, hydrogels are mainly prepared at room temperature. In this study, chitosan gels were prepared at different reaction temperatures (-25, 0 and +25°C). Swelling profiles revealed that with decreasing reaction temperature swelling ratio increased. In addition, the degradation rate of chitosan gels prepared at -25 and +25°C was measured 50.60 and 30.88%, respectively. Results indicate that reaction temperature affects the architecture and characterization results of the gels.

Silver nanoparticles (AgNPs) were successfully synthesized via a bottom-up approach by using aqueous extract of lantana camara (LC) leaves as reducing and stabilizing agent. Characterization studies were done using UV-Vis spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The average size, morphology and shape of the nanoparticles were determined by Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS). A light brown color indicated the synthesis of AgNPs, caused by a surface plasmon resonance (SPR) peak at 460 nm. The silver nanoparticles were used to detect mercury (Hg2+) ions. A color change of the AgNPs solution from light brown to cloudy white due to oxidation of Ag0 to Ag+1 ions was observed. A good selectivity of the AgNPs towards mercury ions in water has been obtained. This method was found to be simple and rapid for detection of Hg2+ ions and demonstrated a potential to be used in environmental colorimetric sensor applications.

Chemical and biological agents effects tissues and organs which cause poisoning, disease, and deterioration. Chemical or biological weapons show significant threats to humankind. Therefore, many studies have presented approaches for protection from biological and chemical agents. There are various types of defence equipments to protect a body from those agents such as developed detectors, protective clothing materials, functional decontaminants, and others. A number of studies have reported about protective clothing against chemical and biological agents, because many of them are dermally active. New protective clothing materials (comfortable, adsorptive, light-weight) combined with active detoxifying/decontaminating nanomaterials have been produced recently. Electrospinning is one of the simplest and most versatile methods to fabricate nanofibers with high surface areas. Electrospun polymeric nanofibers were used as a protective barrier on the textile fabrics. Attempts have been made to incorporate nanoparticles, nanotubes and antimicrobials into electrospun fibers to enhance their functionality. In this contribution, a selection of studies about the use of electrospun nanofibers for protective clothing against chemical and biological agents is summarized.

Biodegradable polymeric micelles are one of the most promising drug delivery platforms due to their biocompatibility, biodegradability, bioavailability, enhanced drug loading, and prolonged circulation. Several micellar systems, composed of amphiphilic block copolymers forming a hydrophobic core and a surrounding hydrophilic shell, have appeared ideal for targeted and controlled delivery of hydrophobic anticancer drugs as well as therapeutic genes and proteins as they remarkably improve water solubility of drugs, prolong lifetime in blood circulation, and degrade into nontoxic products in vivo. Biodegradation of micelles provide the control of drug release and prevents the accumulation of micelle in tissues that may cause long-term cytotoxicity. Although the polymeric biodegradable vehicles have clear advantages of better pharmacological profiles, due to the issues of low in vivo stability, poor cellular uptake, and slow drug release behaviors following uptake by tumor cells, more extensive work is needed to increase their therapeutic benefits to reach the expectations. This chapter covers various biodegradable polymeric micellar systems, methods of preparation, the drug-loading process, release behavior, and highlights the recent advancements in functional biodegradable polymeric micelles for drug-release applications.

The aim of this study was the synthesis and characterization of gelatin- and hydroxyapatite (osteoconductive component of bone)-based cryogels for tissue-engineering applications. Preliminary in vitro and in vivo biocompatibility tests were conducted. Gelatin- and hydroxyapatite-based cryogels of varying concentrations were synthesized using glutaraldehyde as the crosslinking agent. Chemical structure, pore morphology, pore size distribution, mechanical properties, swelling characteristics and degradation profiles of the synthesized cryogels were demonstrated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mercury porosimetry, a mechanical test device, swelling ratio tests and weight loss measurements, respectively. In vitro cell viability and in vivo biocompatility tests were performed in order to show the performance of the cryogels in the biological environment. Changing the concentrations of gelatin, hydroxyapatite and crosslinker changed the chemical structure, pore size and pore size distribution of the cryogels, which in turn resulted in the ultimate behaviour (mechanical properties, swelling ratio, degradation profile). In vitro cell culture tests showed the viability of the cells. The cryogels did not show any cytotoxic effects on the cells. Clinical outcomes and the gross pathological results demonstrated that there was no necrosis noted in the abdominal and thoracic regions at the end of implantation and the implanted cryogel was found to be non-irritant and non-toxic at 12 weeks of implantation. Copyright © 2013 John Wiley & Sons, Ltd.

Cetinkaya, Duygu Uckan/0000-0003-3593-6493; Meydanli, E. Elif Guzel/0000-0001-9072-3322; Bayram, Cem/0000-0001-8717-4668; Bolgen, Nimet/0000-0003-3162-0803; Bolgen, Nimet/0000-0003-3162-0803; KORKUSUZ, PETEK/0000-0002-7553-3915; KILIC, Emine/0000-0003-2984-7638 WOS: 000329845100010 PubMed: 23477355 HEMA-Lactate-Dextran cryogel scaffolds were produced by cryogelation. Mesencyhmal stem cells (MSC) were isolated from rat bone marrow. Critical sized cranial bone defects were created in rat cranium. Stem cells were injected inside the macropores of the cryogel scaffolds prepared from HEMA-Lactate-Dextran possessing the same dimensions with the defect and placed in the cranial bone. The cryogels placed in the defect without stem cells served as control. After selected time intervals the experimental sites were removed from the animals and new bone formation and tissue integration were investigated by histological analysis. The in vivo results exhibited osseous tissue integration within the implant and mineralized functionally stable bone restoration of the cranial defects. Tissue formation started in the macrospores of the scaffold starting from periphery to the center. A significant ingrowth of connective tissue cells and new blood vessels allowed new bone formation. Histological data demonstrated that new bone per total defect area ratio, were not significantly different in "scaffold-stem cells" group compared to that of "scaffold only" group on all time points. However, the blood vessel density was significantly higher in "scaffold-stem cells" group comparing to that of the "scaffold only" group on day 30. "Scaffold-stem cells" given group gave better tissue response score when compared to "scaffold only" group on day 180. Turkish Academy of Sciences (TUBA)Turkish Academy of Sciences This study was performed in the context of the EU-FP6-NoE Expertissues Project. Erhan Piskin was supported by the Turkish Academy of Sciences (TUBA) as a full member.

In this study, polyvinyl alcohol (PVA) and gelatin based cryogels were prepared by crosslinking chemically or physically for tissue engineering applications. Different PVA/Gelatin ratios (100:0, 90:10, 70:30, 50:50) and crosslinking methods have been used to prepare cryogels; chemical and physical structure of the prepared matrices were analysed by FTIR and SEM; swelling and degradation profiles were followed. Chemical and physical crosslinking was obtained by using glutaraldehyde as crosslinker and by applying freeze thawing cycle, respectively. Gelatin concentration and crosslinking method had significant effect on the pore size, swelling ratio and degradation profiles of the cryogels. Biocompatibility of the cryogels were also investigated by MTT assay. SEM was used to investigate the cell morphology on the scaffolds. The MTT assay findings prove that physically crosslinked PVA/Gelatin scaffolds are more biocompatible and enhance more the adhesion and proliferation of mouse embryonic fibroblast cells (MEF) than chemically crosslinked PVA/Gelatin scaffolds. The overall results demonstrated that, the PVA/Gelatin cyrogels as a suitable biomaterial for tissue engineering applications and crosslinking methods affect the architecture and characteristic properties of the cryogels.

Polymeric scaffolds produced by cryogelation technique have attracted increasing attention for tissue engineering applications. Cryogelation is a technique which enables to produce interconnected porous matrices from the frozen reaction mixtures of polymers or monomeric precursors. Chitosan is a biocompatible, biodegradable, nontoxic, antibacterial, antioxidant and antifungal natural polymer that is obtained by deacetylation of chitin, which is mostly found in the exoskeleton of many crustacean. In this study, chitin was isolated from the exoskeleton of blue crap ( Callinectes sapidus ) using a chemical method. Callinectes sapidus samples were collected from a market, as a waste material after it has been consumed as food. Demineralization, deproteinization and decolorization steps were applied to the samples to obtain chitin. Chitosan was prepared from isolated chitin by deacetylation at high temperatures. The chemical compositon of crab shell, extracted chitin and chitosan were characterized with FTIR analyses. And also to determine the physicochemical and functional properties of the produced chitosan; solubility, water binding and fat binding analysis were performed. Chitosan cryogel scaffolds were prepared by crosslinking reaction at cryogenic conditions at constant amount of chitosan (1%, w/v) with different ratios of glutaraldehyde (1, 3, and 6%, v/v) as crosslinker. The chemical structure of the scaffolds were examined by FTIR. Also, the water uptake capacity of scaffolds have been determined. Collectively, the results suggested that the characterized chitosan cryogels can be potential scaffolds to be used in tissue engineering applications.

Electrospinning is a process in which polymer fibers are produced with diameters down to the nanometer range through the action of an electric field imposed on a polymer solution/melt. Distinct properties that make electrospun nanofibrous materials unique are their high surface area, porosity, tensile strength and high extensibility. Indeed the size of the fibers down to nanometer scale make the final structures unique. And since the structure of the nanofibers is very similar to the extracellular matrix, many applications of them are proposed to be used in biomedicine especially for tissue engineeri2ng applications. Many polymers were used to prepare electrospun nanofibers including natural and synthetic ones. Poly(e-caprolactone) (PCL) was used extensively in the tissue engineering field as a synthetic polymer and alternative to natural polymers. The relatively inexpensive production routes, FDA approval, tailorable biodegradability, biocompatibility and easy manipulation make this polymer promising for electrospinning applications. Therefore PCL based electrospun matrices were used in several tissue engineering attempts including skin, bone, vascular and nerve regeneration. This review summarizes the use of electrospun PCL nanofibers in tissue engineering and regenerative medicine applications.

Biomaterials are widely used in diverse applications as substances, materials or important elements of biomedical devices. Biodegradable polymers, both natural and synthetic, have been utilized in applications in which they act as temporary substitutes. Poly(alpha-hydroxy acids), especially lactic acids and glycolic acid and their copolymers with epsilon-caprolactone, are the most widely known and used among all biodegradable polymers. They degrade in vivo into safe end products mainly by hydrolysis in a few weeks to several months, depending on several factors, including molecular structure/morphology, average molecular weight, size and shape. They are processed into tailor-made materials for diverse applications, although mainly for soft and hard tissue repair. Electrospinning is a method of producing nanofibers and nonwoven matrices from their solutions and melts. Several factors affect fiber diameter and resulting nonwoven structures/morphologies. Recently, electrospun matrices made of lactic acids, glycolic acid and epsilon-caprolactone homo- and co-polymers have been attracting increasing attention for fabrication of novel materials for medical use. This review briefly describes poly(alpha-hydroxy acids) and the elecrospinning process, and gives some selected recent applications of electrospun matrices made from these polymers.

NIPA and HEMA-lactate-Dextran-based biodegradable and thermoresponsive cryogels were synthesized at different compositions by cryogelation. Chemical and morphological properties of the HEMA-lactate-Dextran-co-NIPA cryogel matrices were demonstrated by FTIR, SEM, and ESEM. Thermoresponsivity of the prepared cryogels was investigated by DSC, imaging NMR, and swelling studies. For possible use of the cryogels in potential bone tissue engineering applications, either hydrophobic simvastatin was embedded, or hydrophilic simvastatin was incorporated in the cryogels. Release profiles of simvastatin delivering cryogel scaffolds depending on their composition, hydrophobicity or hydrophilicity of loaded simvastatin and the medium temperature were demonstrated.

Volatile organic compounds (VOCs) are significant environmental pollutants and have harmful effects on the human health. In order to detect VOCs, nanofibrous materials received considerable attention due to their unique chemical/physical properties and their high surface area/volume ratio. Electrospun fibers with polyelectrolyte components, conducting polymer composites, and semiconductors were successfully applied as gas sensing interfaces. Increasing the thermal and electrical conductivity of typical insulating polymers, such as nylon-6,6 will allow the development of new and improved ultrasensitive sensors for detection of VOCs. In this study, we report our preliminary results for the production of electrospun Nylon-6,6 nanofibrous matrices after combination with a conductive component for a possible VOC sensor platform. Three dimensional nonwoven nanofibers with various compositions (5,10,15 and 20 wt%) were fabricated by the electrospinning method from Nylon-6,6 polymer solutions dissolved in a 4:1 weight ratio formic acid/acetic acid solution. Chemical and morphological structure of the electrospun matrices were studied by FT-IR and SEM, respectively. The electrospun Nylon-6,6 membranes demonstrated nanofibrous structures with fiber sizes ranging between 32 and 103 nm. By varying the polymer concentration and the conductivity of the polymer solution, changes of the size and the morphology of the final structures are observed.