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In this study, bioactive glass (BG) and copper metal nanoparticles (Cu NPs)-doped poly(Ɛ-caprolactone) (PCL) nanofiber membranes were produced by electrospinning method. Box–Behnken design was used to evaluate the effect of formulation variables including PCL concentration, Cu NPs ratio and BG ratio on nanofiber diameter, and cytotoxicity studies on mouse fibroblasts (L-929) were performed to evaluate the formulation suitable for tissue engineering applications. Membranes containing BG showed enhanced cytocompatibility. It was determined that the toxic properties of the membranes increased with the increase of the Cu NPs ratio. In light of these studies, it was determined that 10% w/v PCL concentration, 15% w/w BG ratio and 0.025% w/w Cu NPs ratio were biocompatible with L929 fibroblast cells. The stability and mineralization ability of the obtained membrane in simulated body fluid were determined by scanning electron microscope and X-ray diffraction analysis. This proved the osteogenic potential of the obtained membrane. Copper ions release from the nanofiber mat was detected by inductively coupled plasma-optical emission spectrometry, and it was found that this membrane had an angiogenic potential. Therefore, this study provides an overview of the effect of formulation variables to fabricate PCL nanofiber scaffolds with BG and Cu NPs for tissue engineering applications.

This study was aimed to produce and characterize the first commercial glass materials with enhanced antibacterial property using conventional melting method. For this purpose, typical container glass composition that contains some specific metal ions, such as silver, strontium, and copper, was used to obtain antibacterial glass samples using classical melting method. After the melting process, antibacterial tests and migration tests were applied to the glasses, and it was found that the glass doped with 2% Ag2O was the best composition. X-rays diffractometer (XRD), thermal expansion coefficient, density, refractive index, hardness, and elastic module results showed that the glass doped with 2% Ag2O was a suitable material as a container glass. High Temperature Melting Observation System studies were performed on the produced antibacterial glass composition, and it was found that the antibacterial glass can be produced in soda lime glass furnaces without changing any furnace design and production parameters. As a result of the characterization studies, it was concluded that the produced container glass doped with silver can be a good candidate for food and pharmaceutical products where bacterial growth is absolutely undesirable.

In this study silver nanoparticles were synthesized by microwave irradiation method using soluble starch as a green capping and reducing agent. The as-prepared soluble starch coated silver nanoparticles (S-Ag NPs) were incorporated in polyvinyl alcohol (PVA) matrix to fabricate nanofibers through electrospinning process. Two different types of crosslinking treatments were used to make the nanofiber mats insoluble in physiological environments. Experimental studies revealed that the choice of the crosslinking treatment led to affect the silver ion release. The nanofiber mats crosslinked with glutaraldehyde have superior silver ion release and stability in simulated body fluid (SBF). The released amounts of silver ions were lower than the toxic level of silver ions for HaCat keratinocytes and human epidermal keratinocytes. After proving antibacterial properties of the glutaraldehyde crosslinked S-Ag NPs loaded PVA nanofiber mats against E. coli and S. aureus it was thought that the nanofibrous mats fabricated in this study can be good candidates as antibacterial scaffolds for wound dressing applications.

This study presents the findings of a research on fabricating composite nanofibrous mats including silver and copper nanoparticles for tissue engineering applications. For this purpose, two different types of silver nanoparticles (soluble starch capped silver nanoparticles, sodium alginate capped silver nanoparticles) and two different types of copper nanoparticles (soluble starch capped copper nanoparticles, sodium alginate capped copper nanoparticles) were successfully incorporated into polyvinyl alcohol (PVA) fibers through electrospinning process. Characterization studies with x-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma spectrometer (ICP) were conducted to determine physical and structural properties of the obtained nanofiber mats. According to SEM analysis it was observed that interconnected and randomly-oriented nanofibers were successfully generated. Additionally, XRD and FTIR studies proved the existence of silver nanoparticles and hydroxapatite on the nanofiber mats immersed in simulated body fluid (SBF) for 7 days. The results indicated that long term silver ion release was achieved. Overall results showed that these nanofibrous mats can be good candidates as multifunctional scaffolds for tissue engineering applications.

This is the first study that investigates the crystallization behavior of strontium- and copper-doped bioactive glasses by both isothermal and nonisothermal methods using differential thermal analysis (DTA) data. DTA results showed that bioactive glasses are suitable for glass-ceramic production. Isothermal and nonisothermal DTA experiments indicated that the crystallization activation energies of strontium-doped bioactive glasses are in the range of 304.1-327.7 kJ/mol, whereas the activation energies of copper-doped bioactive glasses change in the range of 219.13-263.20 kJ/mol. It was found that crystallization activation energies of strontium-doped glasses are higher than those of the copper-doped glasses. Avrami exponent, n, values of bioactive glasses showed that the bulk crystallization was found to predominate in all samples. Results revealed that isothermal and nonisothermal crystallization kinetics of strontium- and copper-doped bioactive glasses are in agreement within the experimental error.

An electrospinning procedure was carried out to fabricate gelatin/poly(ϵ-caprolactone) (Gt/PCL) nanofibers. Response surface methodology based on a three-level, four-variable Box-Behnken design technique was used to model the resultant diameter of the as-spun nanofibers. A second-order model was obtained to describe the relationship between the fiber diameter and the electrospinning parameters, namely Gt concentration, PCL concentration, content of acetic acid in the overall solvent, and content of Gt solution in the blend solution. The individual and the interactive effects of these parameters on the fiber diameter were determined. Validation experiments verified the accuracy of the model which provided a simple and effective method for fabricating nanofibers with a controllable and predictable fiber diameter.

Use of cationic pigment-intercalated bentonite (montmorillonite, Mt) as the latent print development powder was investigated. The cationic dyes, crystal violet (CV) and pararosaniline (PS), were substituted with sodium ions present in the interlayers of Mt by ion exchange mechanism. Organophilic montmorillonites (OMts) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), elemental analysis and Fourier transform infrared spectroscopy (FTIR). TGA results determined the average amount of dye molecules in OMts as 52 mmol/100 g for both PS and CV. Modified bentonite powders were applied to develop fresh and aged (1, 7 and 15 days) fingermarks deposited on non-porous surfaces such as glass, metal and porcelain using a fiberglass brush. Sharp and clear prints with complete ridge details were developed on glass and metal surfaces even for the 15-day-old fingermarks. Surprisingly, CV- and PS-intercalated fingerprint powders successfully worked for the development of the seven-month-old fingerprints on the glass surface. In contrast, physically mixed bentonite and dye mixtures were not very successful in the development of even fresh fingerprints on the glass surface. CV-tagged bentonite also exhibited strong fluorescence at around 500 nm when excited at 450 nm. (C) 2013 Elsevier B.V. All rights reserved.

This review focuses on recent advances in the development and use of nanoscale silicate bioactive glasses for medical applications. In the context of materials for bone substitution, dental applications, and bone tissue engineering, nanoscale bioactive glasses have been gaining attention due to their expected superior osteoconductivity when compared with conventional (micrometer-sized) bioactive glass materials. A detailed overview of recent developments in the field of nanoscale bioactive glasses will be given, including a summary of common fabrication methods and diverse application areas which include tissue engineering scaffolds and coatings, drug delivery devices, and dentistry. The nanofeatures characteristic of this type of bioactive glasses and the possibilities to expand their use in biomedical applications (nanomedicine) are highlighted.

Extended Abstract Tissue damage and degenerative diseases such as large bone defects are among the most human health issues which lead to organ failure and death all over the world [1-3]. Bone tissue engineering emerges a promising approach to repair bone defects, especially large bone defects resulting from trauma, infections, tumors or genetic malformations [2-4]. The development of scaffolds and their processing into structures are becoming increasingly important in bone tissue engineering applications. Three-dimensional (3D) scaffolds should show a highly porous, open structure to allow a proper vascularisation of the implant, as well as the flow of nutrients and waste products through the scaffold. Major issues of bone tissue engineering scaffolds include the use of appropriate matrix materials for scaffolds, control of porosity and pore characteristics of scaffolds, mechanical strength of scaffolds as well as scaffold degradation properties [5]. Ideal bioactive porous scaffolds, which are used in bone tissue engineering applications, should meet multifunctional properties such as angiogenesis, osteostimulation and antibacterial properties for the treatment of large bone defects [2]. Among these properties, angiogenesis plays an important role for the formation and repair of new tissue because blood vessels provide for newly formed tissues to receive nutrients and oxygen. The stimulation of angiogenesis by the delivery of inorganic ions from biomaterial scaffolds provide to reduce cost of treatments and also prevent biological side effects when compared to the use of growth factors and so it has been attracting considerable interest in recent years [6]. The focus of this study is on advanced bioactive scaffolds enabling internal growth of tissue and controlled delivery of therapeutic ion. To be able to achieve this goal, in the first stage bioactive glass (composition in weight; 45% SiO2, 24.5% Na2O, 6% P2O5, 24.5% CaO, 2% CuO) were developed which have antibacterial and angiogenic properties. After the production of bioactive glass, bioactive glass/polymer 3D composite multifunctional scaffolds were fabricated by using foam replication technique. Then, they were coated with alginate at different percentages (in weight; 1, 2, 3 %) to improve the properties of them. The obtained scaffolds were immersed in simulated body fluid (SBF) at different time points (1, 7, 14 and 28 day) to investigate the bioactivity and biodegradability behavior of the samples. Physical and micro structural properties of the obtained scaffolds were determined by using different characterization techniques. Scanning electron microscopy investigations showed that scaffolds have highly porous structure with a good pore interconnectivity. After immersion in SBF for 28 days, the hydroxyapatite layer formation was observed significantly on the surface of the scaffolds. X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis also verified the bioactivity of the obtained scaffolds. Characteristic chemical bonds which belongs to hydroxyapatite were obtained with FTIR and degree of hydroxyapatite was detected from the result of XRD analysis. Physical and mechanical properties of the composite scaffolds were studied and compared with each other. Inductively Coupled Plasma (ICP) analysis was also applied to investigate the copper release behavior of the scaffolds in SBF and the results indicated that the alginate coated scaffolds allowed controlled release of copper ions but in low amounts compared to uncoated ones. The overall results showed that three dimensional composite scaffolds could be promising candidates for bone tissue engineering applications.

The current research was conducted to propose a nanocomposite material, which could be suitable to be used as a scaffold for bone tissue engineering applications. For this purpose, nanocomposite fibers of gelatin, poly(e-caprolactone) (PCL), and bioactive glass were successfully fabricated via electrospinning process. In this context, response surface methodology based on a three-level, four-variable Box-Behnken design was adopted as an optimization tool to choose the most appropriate parameter settings to obtain the desired fiber diameter. The investigation, based on a second order polynomial model, focused on the analysis of the effect of both solution and processing parameters on the fiber diameter and its standard deviation. In optimum conditions (bioactive glass content of 7.5% (w/v), applied voltage of 25kV, tip-to-collector distance of 12.5cm, and flow rate of 1mL/h), the fiber diameter was found to be 584±337nm which was in good agreement with the predicted value by the developed models (523±290nm). Analytical tools such as scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and differential thermal analyzer were used for further evaluation of the optimized nanocomposite mat. The overall results showed that nanocomposite scaffolds could be promising candidates for tissue engineering applications.

In the present study, an electrospinning procedure was carried out in order to develop a simple and effective tool for fabricating gelatin/bioactive glass (Gt/BG) nanofibers with a controllable and predictable fiber diameter. For this purpose, a quadratic model was obtained within the context of response surface methodology based on a three-level, three-variable Box–Behnken design technique to describe the relationship between the fiber diameter and the electrospinning parameters, namely BG content, tip-to-collector distance, and flow rate. Meanwhile, the quality of fit of the model was evaluated by the coefficients of determination (R-square) and the analysis of variances. Moreover, the adequacy of the model was examined by conducting additional experiments that were not employed in the model generation, Bu çalışmada, malzeme ve proses değişkenlerinin jelatin/biyoaktif cam (Gt/BG) nanokompozit liflerinin çapı üzerindeki etkilerinin incelenmesi hedeflenmiştir. Bu amaçla; farklı oranlarda biyoaktif cam tozu içeren jelatin çözeltilerine elektrospinning işlemi uygulanarak nanokompozit malzemeler üretilmiştir. Biyoaktif cam içeriğinin, uç ile toplayıcı arasındaki açıklığın ve çözelti akış hızının ortalama lif çapı üzerindeki etkileri yanıt yüzey yöntemi kullanılarak incelenmiştir. Sonuç olarak; üç değişkenli ve üç seviyeli Box–Benkhen tasarım yöntemi kullanılarak ikinci dereceden bir model oluşturulmuş ve geliştirilen bu model aracılığı ile değişkenlerin etkinlikleri değerlendirilerek, hedeflenen lif çapının sağlanması için gerekli proses koşullarının tahmin edilebileceği basit ve etkin bir yöntem geliştirilmiştir.

We report a study on polymer-mediated immobilization of non-aggregated Ag nanoparticles on planar glass substrates and the resultant surface-enhanced Raman scattering (SERS) activity using Rhodamine 6G (R6G) as a model molecule. Ag colloidal solution with an average particle diameter of 70 nm was prepared by citrate reduction of AgNO3 using the Lee-Meisel method, and subsequent fractionation by filtration. A self-assembled polyallylamine hydrochloride (PAH) monolayer was employed as the intermediate polymer layer. We have shown that the coverage density of Ag nanoparticles on the glass substrates correlates with the amount of adsorbed PAH. This parameter can be easily controlled by varying the pH and ionic strength during polymer deposition. The highest coverage density was obtained for the polymer deposition from buffer solutions at pH 9.0, which additionally contained 0.25 M NaCl. The SERS-active substrates were robust and stable in 0.5 M NaCl solutions, as well as under extreme acidic and basic conditions. The glass substrates with immobilized non-aggregated Ag nanoparticles exhibited SERS enhancement and provided in situ detection sensitivity of R6G at 5 ppt level, with estimated surface coverage of two to four R6G molecules per silver particle. We found that adsorption of R6G in the presence of N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid) (HEPES) buffer resulted in complete inhibition of photodecomposition of adsorbed R6G molecules. Studies of the effect of sodium chloride on the SERS activity of the glass substrates with individually attached nanoparticles showed that chloride anions resulted in a two to threefold increase in SERS intensity. Our approach has enabled the isolation of chloride-activated SERS enhancement from contributions arising from nanoparticle aggregation. The observed SERS enhancement in salt solutions results from coadsorption of chloride ions by the silver surface, and manifests itself in changing of orientation of adsorbed R6G molecules. The observed enhancement was reversed by exposing the substrate to 514-nm laser radiation, which resulted in the cleavage of AgCl bonds. Copyright © 2006 John Wiley & Sons, Ltd.

The rheological characterizations of concentrated suspensions are generally carried out assuming “well-mixed” suspensions. However, the variation of the concentration distributions of the ingredients of the formulation, i.e., the “goodness of mixing”, the size and shape distributions of the particle clusters and the rheological behavior of the suspension all depend on the thermo-mechanical history that the suspension is exposed to during the mixing process. Here, various experimental tools are used for the characterization of the degree of mixedness (concentration distributions) of various ingredients along with the characterization of rheological material functions, wall slip behavior and the maximum packing fraction of a graphite/elastomer suspension. The degree of mixedness values of the ingredients of the suspensions processed using batch and continuous processes and under differing operating conditions were characterized quantitatively using wide-angle X-ray diffraction and thermo gravimetric analysis and were elucidated under the light of the electrical properties of the suspension as affected by the mixing process. Upon achieving better homogeneity of the graphite particles and the binder and decreases in the size and breadth of the size distributions of particle clusters (as inferred from electrical measurements and maximum packing fraction values), the elasticity (storage modulus) and the shear viscosity (magnitude of the complex viscosity from small-amplitude oscillatory shear and shear viscosity from steady torsional and capillary rheometry) of the suspension decreased significantly and the wall slip velocity values increased. These findings demonstrate the intimate relationships that exist between the rheological behavior of concentrated suspensions and the thermo-mechanical history that they are exposed to during the processing stage and suggest that the preparation conditions for suspensions should be carefully selected and well documented to achieve reproducible characterization of rheological material functions.

A grazing incidence X-ray diffraction technique was developed to characterize the effectiveness of the coating of the solid particles by the binder in energetic formulations and was used in conjunction with scanning electron microscopy, traditional wide-angle X-ray diffraction, and specific gravity measurements to probe the microstructure of PAX-12 granules. The grazing incidence X-ray technique was applied to granules formed upon slurry coating and indicated different X-ray scattering characteristics for high- and low-sensitivity granules, suggesting significant differences in the distribution of the binder at the surface of the granules. The granules were made by slurry-coating crystals of epsilon CL-20 with cellulose acetate butyrate, a binder, and bis-(2,2 dinitropropyl acetal/formal), a plasticizer. Granules with high sensitivity to impact and friction were shown to have an interior that was relatively porous and that consisted of uncoated CL-20 crystals. Their surface had regions with a thick layer ...

This article presented a study on the effects of solution properties (i.e., gelatin concentration, alginate concentration, content of alginate solution in the blend solution, and content of acetic acid in the solvent of gelatin solution) on the average diameter of electrospun gelatin/sodium alginate nanofibers, as well as its standard deviation. For this purpose, blend solutions of two natural polymers (gelatin and sodium alginate) were prepared both in the absence and presence of ethanol. Response surface methodology based on a three-level, four-variable Box-Benkhen design was employed to define quadratic relationships between the responses and the solution properties. The individual and interactive effects of the solution properties were determined. Moreover, the adequacy of the models was verified by the validation experiments. Results showed that the average diameters of the resultant nanofibers were 68-166 nm and 90-155 nm in the absence and presence of ethanol, respectively. The experimental results were in good agreement with the predicted response values. Hence, this study provides an overview on the fabrication of gelatin/sodium alginate nanofibers with targeted diameter, which may have potential to be used in the field of tissue engineering.

This study intends to design magnetite (Fe3 O4 )-based magnetic fingerprint powders with different particle size distributions. It also investigates the influence of particle size distribution on the visualization of latent fingermarks with as little background staining as possible on the surfaces with various porosities in a systematic way. Two strategies were used to prepare the magnetic fingerprint formulations for this study: milling of coarse magnetite particles for different durations, and mixing of sieved fine particles with different size ranges with coarse particles. Particle size analyses of the prepared magnetic powders, optical microscopy-based roughness analysis of the surfaces and SEM measurements of the visualized fingerprints and representative powders were performed. Mag2 of the formulations prepared through milling and Mag5 and Mag6 of the formulations prepared through sieving and mixing were more successful in the development of latent prints than the rest of the solutions.

Positively charged silver nanoparticles, Ag [+], obtained by UV-assisted reduction of silver nitrate using branched poly(ethyleneimine) (BPEI) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) solutions as reducing agents, were immobilized on glass surfaces to produce substrates active in surface-enhanced Raman scattering (SERS). Negatively charged silver nanoparticles, Ag [-], synthesized via a modified citrate reduction method, were also investigated for comparison. At a sparse surface coverage of 30 nanoparticles/microm(2), substrates with immobilized Ag [+] showed increasing SERS sensitivity to a variety of anions in water in the order SO(4)(2-)CN(-)SCN(-) approximately ClO(4)(-), with corresponding binding constants of 10(5), 3.3 x 10(5), and 10(7) (for both SCN- and ClO(4)(-)) M(-1), respectively. This order followed the Hofmeister series of anion binding in water. Significantly, substrates with Ag [+] allowed limit of detection values of 8.0 x 10(-8) M (8 ppb) and 2.7 x 10(-7) M (7 ppb) for environmentally relevant perchlorate (ClO(4)(-)) and cyanide (CN(-)) anions, respectively. In contrast, substrates with immobilized Ag [-], even upon subsequent modification by a monolayer of BPEI for positive surface charge of the nanoparticles, showed a drastically lower sensitivity to these anions. The high sensitivity of substrates with Ag [+] for anion detection can be attributed to the presence of two types of functional groups, amino and amide, on the nanoparticle surface resulting from UV-assisted fragmentation of BPEI chains. Both amino and amide provide strong binding of anions with Ag [+] nanoparticles due to the synergistic effect through a combination of electrostatic, hydrogen bonding, and dispersive interactions.

Branched polyethyleneimine (BPEI) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) were used collaboratively to reduce silver nitrate under UV irradiation for the synthesis of positively charged silver nanoparticles. The effects of molar ratio of the ingredients and the molecular weight of BPEI on the particle size and distribution were investigated. The mechanism for the reduction of Ag+ ions in the BPEI/HEPES mixtures entails oxidative cleavage of BPEI chains that results in the formation of positively charged BPEI fragments enriched with amide groups as well as in the production of formaldehyde, which serves as a reducing agent for Ag+ ions. The resultant silver nanoparticles are positively charged due to protonation of surface amino groups. Importantly, these positively charged Ag nanoparticles demonstrate superior SERS activity over negatively charged citrate reduced Ag nanoparticles for the detection of thiocyanate and perchlorate ions; therefore, they are promising candidates for sensing and detection of a variety of negatively charged analytes in aqueous solutions using surface-enhanced Raman spectroscopy (SERS).

This study concerns the design of protein-resistant polymer adsorbed layers for the control of surface binding of biospecific recognition entities. Polymer surface layers were prepared using the adsorption of poly(allylamine hydrochloride) (PAH), poly(l-lysine) (PL), and branched and linear polyethyleneimine (PEI) and further modified by the covalent attachment of biotin for specific avidin attachment. The adsorption of PAH, PL, and PEI on silicon substrates was studied as a function of pH and ionic strength using ellipsometry. Average dry layer thicknesses of approximately 10, approximately 5, approximately 9, and approximately 3 A (+/-1 A) were obtained when polymer adsorption occurred from solutions at pH 9.5 that contained 0.5 M NaCl for PAH, PL, branched PEI, and linear PEI, respectively. These polymers showed significant differences in their efficiency to suppress nonspecific avidin adsorption. At low ionic strength, avidin adsorption occurred on all polymer-coated surfaces at basic pH values, despite the same positive electrostatic charge for protein globules and the surface. Though the net electrostatic repulsion between avidin molecules and branched PEI was efficiently screened in a protein solution of pH 7 and 0.15 M NaCl, branched-PEI coatings of high molecular weight were unique in their ability to provide avidin-resistant surfaces as a result of steric hindrance from the branched architecture of adsorbed polymer chains. All polymers studied were effective in suppressing avidin adsorption at pH 3 as a result of protonation of the avidin surface functional groups at this pH. Branched-PEI-coated surfaces were also effective for the suppression of smaller positively charged proteins such as lysozyme and ribonuclease A at pH 7 and 0.15 M NaCl. They were also resistant to the adsorption of negatively charged proteins such as BSA and fibrinogen at pH 7 and 0.75 M NaCl. Furthermore, by using PEI-modified protein-repellent surfaces, selective binding of avidin was achieved to surface-bound silver nanoparticles, which should provide a promising application for the label-free detection of biological species using surface-enhanced Raman scattering (SERS).

Oxidation of the Ag nanoparticle surface has a dramatic effect on the adsorption, orientation, and SERS detection limit of nitroaromatic molecules in aqueous solutions. Ultrasensitive SERS detection of p-nitrophenol can be achieved when oxidation of surface-immobilized Ag nanoparticles is inhibited by replacing the oxygen dissolved in water with argon gas. The presence of silver oxide at the nanoparticle surface hinders charge transfer between the aromatic ring and the underlying Ag metal surface and drastically decreases the overall detection sensitivity.