Tuning the Cell-Adhesive Properties of Two-Component Hybrid Hydrogels to Modulate Cancer Cell Behavior, Metastasis, and Death Pathways.

This work presents a polysaccharide and protein-based two-component hybrid hydrogel integrating the cell-adhesive gelatin-tyramine (G-Tyr) and nonadhesive hyaluronic acid-tyramine (HA-Tyr) through enzyme-mediated oxidative coupling reaction. The resulting HA-Tyr/G-Tyr hydrogel reflects the precise chemical and mechanical features of the cancer extracellular matrix and is able to tune cancer cell adhesion upon switching the component ratio. The cells form quasi-spheroids on HA-Tyr rich hydrogels, while they tend to form an invasive monolayer culture on G-Tyr rich hydrogels. The metastatic genotype of colorectal adenocarcinoma cells (HT-29) increases on G-Tyr rich hydrogels which is driven by the material's adhesive property, and additionally confirmed by the suppressed gene expressions of apoptosis and autophagy. On the other hand, HA-Tyr rich hydrogels lead the cells to necrotic death via oxidative stress in quasi-spheroids. This work demonstrates the ideality of HA-Tyr/G-Tyr to modulate cancer cell adhesion, which also has potential in preventing primary metastasis after onco-surgery, biomaterials-based cancer research, and drug testing.

A new approach in stem cell research-Exosomes: Their mechanism of action via cellular pathways.

Exosomes are nano-sized vesicles surrounded by a lipid membrane, which tend to be secreted toward extra-cellular environments. Despite being defined as vesicles involved in excretion of molecular wastes by Rose Johnstone in the 1970s, further studies revealed them to be effective in various biological processes such as cancer development, regulation of the immune system, intercellular communication, stem cell biology, and tissue/organ regeneration. Although many studies dealing with the role of exosomes in stem cell differentiation and the use of exosomes isolated from stem cells for the treatment of several diseases have been published, the involved mechanisms remain largely unknown. Further understanding of these mechanisms, which include the involved cellular pathways, may improve the use of exosomes in diagnostic and treatment methods, especially for those involving stem cells. Here, we describe some recent data describing the action mechanism of stem cell-derived exosomes focusing on the implicated cellular pathways, hoping to provide novel information that will be useful for cell biology scientists working in this field.

Evaluation of different isotherm models, kinetic, thermodynamic, and copper biosorption efficiency of Lobaria pulmonaria (L.) Hoffm.

UNLABELLED: The biosorption characteristics of Cu(II) ions from aqueous solution using Lobaria pulmonaria (L.) Hoffm. biomass were investigated. The biosorption efficiency of Cu(II) onto biomass was significantly influenced by the operating parameters. The maximum biosorption efficiency of L. pulmonaria was 65.3% at 10 mg/L initial metal concentration for 5 g/L lichen biomass dosage. The biosorption of Cu(II) ions onto biomass fits the Langmuir isotherm model and the pseudo-second-order kinetic model well. The thermodynamic parameters indicate the feasibility and exothermic and spontaneous nature of the biosorption. The effective desorption achieved with HCl was 96%. Information on the nature of possible interactions between the functional groups of the L. pulmonaria biomass and Cu(II) ions was obtained via Fourier transform infrared (FTIR) spectroscopy. The results indicated that the carboxyl (-COOH) and hydroxyl (-OH) groups of the biomass were mainly involved in the biosorption of Cu(II) onto L. pulmonaria biomass. The L. pulmonaria is a promising biosorbent for Cu(lI) ions because of its availability, low cost, and high metal biosorption and desorption capacities. IMPLICATIONS: Lobaria pulmonaria is a promising biosorbent for Cu(II) ions because of its availability, low cost, and high metal biosorption and desorption capacities. To the best of our knowledge, this is the first paper on the biosorption Cu by L. pulmonaria.

Protein A immunosensor for the detection of immunoglobulin G by impedance spectroscopy.

A novel highly sensitive electrochemical impedimetric Protein A immunosensor for the determination of immunoglobulin G (IgG) was developed by immobilization of Protein A within a newly synthesized, and characterized polymer, poly(maleicanhydride-alt-decene-1). TiO2 nanoparticles (10-30 nm) were synthesized, characterized with X-ray diffraction, transmission electron microscopy and Brunauer-Emmett-Teller surface analysis. The electron transfer between IgG and the poly(maleicanhydride-alt-decene-1)-TiO2-Protein A is quasireversible with a formal potential of 225 mV vs Ag|AgCl. The response of the poly(maleicanhydride-alt-decene-1)-TiO2-Protein A immunosensor was proportional to IgG concentration with a correlation coefficient of 0.9963. The detection limit and linear range was 0.57 ng mL(-1) and 0.0062-500 µg mL(-1), respectively. Impedance measurments showed that synthesized TiO2 nanoparticles have better conducting properties compared with commercial degussa P25 TiO2 nanoparticles. The nonspecific binding of anti-MBP was 10 %. The label-free impedimetric immunosensor provided a simple and sensitive detection method for the specific determination of IgG in human serum.

Carboxymethylcellulose-gelatin-superoxidase dismutase electrode for amperometric superoxide radical sensing.

A novel, highly sensitive superoxide dismutase biosensor for the direct and simultaneous determination of superoxide radicals was developed by immobilization of superoxide dismutase within carboxymethylcellulose-gelatin on a Pt electrode surface. The parameters affecting the performance of the biosensor were investigated. The response of the CMC-G-SOD biosensor was proportional to O (2) (·-) concentration and the detection limit was 1.25 × 10(-3) mM with a correlation coefficient of 0.9994. The developed biosensor exhibited high analytical performance with wider linear range, high sensitivity and low response time. The biosensor retained 89.8% of its sensitivity after use for 80 days. The support system enhanced the immobilization of superoxide dismutase and promoted the electron transfer of superoxide dismutase minimizing its fouling effect. The biosensor was quite effective not only in detecting O (2) (·-) , but also in determining the antioxidant properties of acetylsalicylic acid-based drugs and the anti-radical activity of healthy and cancerous human brain tissues.

Decellularized Bone Extracellular Matrix-Coated Electrospun PBAT Microfibrous Membranes with Cell Instructive Ability and Improved Bone Tissue Forming Capacity.

Current approaches to develop bone tissue engineering scaffolds have some limitations and shortcomings. They mainly suffer from combining mechanical stability and bioactivity on the same platform. Synthetic polymers are able to produce mechanically stable sturctures with fibrous morphology when they are electrospun, however, they cannot exhibit bioactivity, which is crucial for tissue engineering and regenerative medicine. One current strategy to bring bioactivity in synthetic materials is to combine extracellular matrix (ECM)-sourced materials with biologically inert synthetic materials. ECM-sourced materials without any modifications are mechanically unstable; therefore, reinforcing them with mechanically stable platforms is indispensable. In order to overcome this bifacial problem, we have demonstrated that poly(butylene adipate-co-terephthalate) (PBAT) electrospun microfibrous membranes can be successfully modified with decellularized bone ECM to endow fibers with bioactive hydrogel and mimic natural micro-features of the native bone tissue. The developed structures have been shown to support osteogenesis, confirmed by histochemical staining and gene expression studies. Furthermore, ECM-coated PBAT fibers, when they were aligned, supplied an improved level of osteogenesis. The strategy demonstrated can be adapted to any other tissues, and the emerging microfibrous, mechanically stable, and bioactive materials can find implications in the specific fields of tissue engineering and regenerative medicine.

Omics technologies for high-throughput-screening of cell-biomaterial interactions.

Recent research effort in biomaterial development has largely focused on engineering bio-instructive materials to stimulate specific cell signaling. Assessing the biological performance of these materials using time-consuming and trial-and-error traditional low-throughput screening techniques remains a critical challenge in the field. In contrast, the use of increasingly sophisticated omics technologies to facilitate high-throughput screening of unbiased global understanding of cell-biomaterial interactions at gene, epigenetic, mRNA, protein, metabolite, and lipid levels holds great potential to predict the therapeutic outcome of biomaterials with specific properties. In this review, we highlight the potential use of omics technologies - namely transcriptomics, proteomics, metabolomics and lipidomics - in biomaterial design and deciphering of the fundamental cell behaviors (e.g., adhesion, migration, differentiation) in response to cell-biomaterial interactions. Moreover, the potential challenges and prospects of high-throughput analysis platforms are discussed rationally, providing an insight into the developing field and its use in biomaterials science.

Xenogenic Neural Stem Cell-Derived Extracellular Nanovesicles Modulate Human Mesenchymal Stem Cell Fate and Reconstruct Metabolomic Structure.

Extracellular nanovesicles, particularly exosomes, can deliver their diverse bioactive biomolecular content, including miRNAs, proteins, and lipids, thus providing a context for investigating the capability of exosomes to induce stem cells toward lineage-specific cells and tissue regeneration. In this study, it is demonstrated that rat subventricular zone neural stem cell-derived exosomes (rSVZ-NSCExo) can control neural-lineage specification of human mesenchymal stem cells (hMSCs). Microarray analysis shows that the miRNA content of rSVZ-NSCExo is a faithful representation of rSVZ tissue. Through immunocytochemistry, gene expression, and multi-omics analyses, the capability to use rSVZ-NSCExo to induce hMSCs into a neuroglial or neural stem cell phenotype and genotype in a temporal and dose-dependent manner via multiple signaling pathways is demonstrated. The current study presents a new and innovative strategy to modulate hMSCs fate by harnessing the molecular content of exosomes, thus suggesting future opportunities for rSVZ-NSCExo in nerve tissue regeneration.

Ultrasonics-Assisted Effective Isolation and Characterization of Exosomes from Whole Organs.

Exosomes, natural and nanovesicular structures surrounded by a lipid membrane, tend to be secreted toward extracellular environments by almost all cell types. Late studies have shown them to be effective in several complex biological processes like cancer development and metastasis, immune system regulation, cellular signal transduction, stem cell differentiation, and regeneration of damaged tissues. Although there are many studies dealing with the role of exosomes in the aforementioned fields, the mechanisms remained largely unknown. There is therefore a need for further study on exosome isolation from different sources. While researchers mostly use serum, plasma, urine, and cell culture media as a source for exosome isolation, there are no studies dealing with direct isolation of exosomes from whole organs in literature. In this study, we propose a protocol for effective isolation of exosomes from whole organs. Mouse brain, heart, and liver were chosen as the sources of exosomes in this study. Isolated exosomes were successfully characterized with BCA test, western blot, transmission electron microscopy and ELISA.

Mechanically robust hybrid hydrogels of photo-crosslinkable gelatin and laminin-mimetic peptide amphiphiles for neural induction.

Self-assembling bio-instructive materials that can provide a biomimetic tissue microenvironment with the capability to regulate cellular behaviors represent an attractive platform in regenerative medicine. Herein, we develop a hybrid neuro-instructive hydrogel that combines the properties of a photo-crosslinkable gelatin methacrylate (GelMA) and self-assembling peptide amphiphiles (PAs) bearing a laminin-derived neuro-inductive epitope (PA-GSR). Electrostatic interaction and ultraviolet light crosslinking mechanisms were combined to create dual-crosslinked hybrid hydrogels with tunable stiffness. Spectroscopic, microscopic and theoretical techniques show that the cationic PA-GSR(+) electrostatically co-assembles with the negatively charged GelMA to create weak hydrogels with hierarchically ordered microstructures, which were further photo-crosslinked to create mechanically robust hydrogels. Dynamic oscillatory rheology and micromechanical testing show that photo-crosslinking of the co-assembled GelMA and PA-GSR(+) hydrogel results in robust hydrogels displaying improved stiffness. Gene expression analysis was used to show that GelMA/PA-GSR(+) hydrogels can induce human mesenchymal stem cells (hMSCs) into neural-lineage cells and supports neural-lineage specification of neuroblast-like cells (SH-SY5Y) in a growth-factor-free manner. Also, metabolomics analysis suggests that the hydrogel alters the metabolite profiles in the cells by affecting multiple molecular pathways. This work highlights a new approach for the design of PA-based hybrid hydrogels with robust mechanical properties and biological functionalities for nerve tissue regeneration.

Untargeted multi-omic analysis of colorectal cancer-specific exosomes reveals joint pathways of colorectal cancer in both clinical samples and cell culture.

Exosomes are naturally secreted nano-vesicles consisting of biochemical molecules including RNAs, metabolites, lipids, and proteins, that emerge as diagnostic tools and disease-specific reporters. Here we offer a systematic and integrative approach for the simultaneous analysis of altered molecules namely metabolites, lipids, and proteins. These components tend to augment the discovery of low abundance signature components, and assist in explanation of molecular basis of colorectal cancer (CRC). In order to investigate CRC-derived exosomes, we selected mi-R19a, miR-21, miR-92a, and miR-1246 positive exosomes for downstream experiments. The overall multi-omic changes were investigated comparatively in cell culture and serum samples. Following a systematic multi-omic study, 37 (cell culture) and 31 (serum) metabolites; 130 (cell culture) and 56 (serum) lipids; 9 (cell culture) and 13 (serum) proteins were seen to be differentially expressed (p < 0.05), enabling discrimination between CRC and control. By using these enriched components, we demonstrated that the joint pathways mainly involving fatty acid and amino acid metabolism related pathways changed in CRC significantly. We conclude that this study increases our understanding of molecular basis of CRC, and provides potential exosomal biomarkers for the non-invasive detection, and discrimination of CRC.

Alginate copper oxide nano-biocomposite as a novel material for amperometric glucose biosensing.

A novel amperometric glucose biosensor based on alginate-CuO nano-biocomposite and glucose oxidase (GOD) film was developed and characterized. The properties of the alginate-CuO-GOD film were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric measurements were employed to characterize the analytical performance of the biosensor. Several parameters including amount of alginate, concentration of GOD and cross-linkers, amount of CuO nanoparticles, and effect of pH were studied and optimized. Under optimal conditions, the developed alginate-CuO-GOD biosensor was shown to have two linear ranges; from 0.04mM to 3mM (with a correlation coefficient of 0.9996 and the sensitivity of 30.443µAmM-1cm-2) and from 4mM to 35mM (with a correlation coefficient of 0.9994 and the sensitivity of 7.205µAmM-1cm-2). The overall detection limit was estimated to be 1.6µM (signal-to-noise ratio of 3) and the Km value of 2.82mM. The biosensor exhibited rather good performance with long-term stability (remainder of activity is 78% after 15days) and significant specificity for glucose when compared to possible interfering molecules such as ascorbic acid, uric acid and acetaminophen.

Fabrication of human hair keratin/jellyfish collagen/eggshell-derived hydroxyapatite osteoinductive biocomposite scaffolds for bone tissue engineering: From waste to regenerative medicine products.

In the present study, we aimed at fabricating an osteoinductive biocomposite scaffold using keratin obtained from human hair, jellyfish collagen and eggshell-derived nano-sized spherical hydroxyapatite (nHA) for bone tissue engineering applications. Keratin, collagen and nHA were characterized with the modified Lowry method, free-sulfhydryl groups and hydroxyproline content analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and thermal gravimetric analysis (TGA) which confirmed the success of the extraction and/or isolation processes. Human adipose mesenchymal stem cells (hAMSCs) were isolated and the cell surface markers were characterized via flow cytometry analysis in addition to multilineage differentiation capacity. The undifferentiated hAMSCs were highly positive for CD29, CD44, CD73, CD90 and CD105, but were not seen to express hematopoietic cell surface markers such as CD14, CD34 and CD45. The cells were successfully directed towards osteogenic, chondrogenic and adipogenic lineages in vitro. The microarchitecture of the scaffolds and cell attachment were evaluated using scanning electron microscopy (SEM). The cell viability on the scaffolds was assessed by the MTT assay which revealed no evidence of cytotoxicity. The osteogenic differentiation of hAMSCs on the scaffolds was determined histologically using alizarin red S, osteopontin and osteonectin stainings. Early osteogenic differentiation markers of hAMSCs were significantly expressed on the collagen-keratin-nHA scaffolds. In conclusion, it is believed that collagen-keratin-nHA osteoinductive biocomposite scaffolds have the potential of being used in bone tissue engineering.

Simultaneous quantification of Myelin Basic Protein and Tau proteins in cerebrospinal fluid and serum of Multiple Sclerosis patients using nanoimmunosensor.

This study was aimed at the development of an immunosensor for the simultaneous quantification of Myelin Basic Protein (MBP) and Tau proteins in cerebrospinal fluid (CSF) and serum, obtained from Multiple Sclerosis (MS) patients. The newly developed GO/pPG/anti-MBP/anti-Tau nanoimmunosensor has been established by immobilization of MBP and Tau antibodies. The newly developed nanoimmunosensor was tested, optimized and characterized using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The developed nanoimmunosensor was seen to have detection limits of 0.30nM for MBP and 0.15nM for Tau proteins which were sufficient for the levels to be analysed in neuro-clinic. The clinical study performed using CSF and serum of MS patients showed that the designed nanoimmunosensor was capable of detecting the proteins properly, that were essentially proven by ELISA.

Bioengineering Functional Copolymers. IX. Poly[(maleic anhydride-co-hexene-1)-g-poly(ethylene oxide)].

Amphiphilic bioengineering copolymers having a combination of hydrophilic/hydrophobic linkages and polyelectrolyte behavior, along with an ability to interact with biomacromolecules, in particular with the invertase enzyme, have been synthesized by (a) complex-radical copolymerization of maleic anhydride (MA, the acceptor) and hexene-1 (H-1, the donor) monomers with benzoyl peroxide as the initiator in 1,4-dioxane at 65 degrees C under high-conversion conditions and (b) subsequent grafting (polyesterification) of synthesized poly(MA-alt-H-1) with alpha-methoxy-omega-hydroxy-poly(ethylene oxide) (PEO). Copolymerizations were also carried out in the steady state, in order to essentially reduce the effect of copolymer composition drift. The values of the monomer reactivity ratios (r(1) and r(2)) determined by using the known terminal models of Fineman-Ross (FR) and Kelen-Tüdös (KT), as well as by nonlinear regression (NLR) analysis, are: r(1) = 0.16 and r(2) = 0.30 (FR), r(1) = 0.14 and r(2) = 0.27 (KT), and r(1) = 0.15 and r(2) = 0.29 (NLR), respectively. All the copolymers and graft copolymers were characterized by FTIR spectroscopy, (1)H{(13)C} NMR spectroscopy, viscometric measurements, and chemical (acid number), thermal (DSC and TGA), and X-ray diffraction analyses. Unlike poly(MA-alt-H-1)s, PEO macrobranched graft copolymers exhibit expressed polyelectrolyte and swelling behavior in diluted and concentrated dioxane solutions, respectively. The copolymer and its PEO hyperbranched derivatives can be used as carriers for enzyme immobilization.

Enhancement of aptamer immobilization using egg shell-derived nano-sized spherical hydroxyapatite for thrombin detection in neuroclinic.

In the present study, we describe the sonochemical isolation of nano-sized spherical hydroxyapatite (nHA) from egg shell and application towards thrombin aptasensing. In addition to the sonochemical method, two conventional methods present in literature were carried out to perform a comparative study. Various analysis methods including Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Energy-Dispersive Analysis of X-Rays (EDAX), and Thermal Gravimetric Analysis (TGA) have been applied for the characterization of nHA and its nanocomposite with marine-derived collagen isolated from Rhizostoma pulmo jellyfish. TEM micrographs revealed the sonochemically synthesized nHA nanoparticles to have a unique porous spherical shape with a diameter of approximately 60-80nm when compared to hydroxyapatite nanoparticles synthesized using the other two methods which had a typical needle shaped morphology. EDAX, XRD and FTIR results demonstrated that the obtained patterns belonged to hydroxyapatite. Electrochemical impedance spectroscopy (EIS) is the main analyzing technique of the developed thrombin aptasensor. The proposed aptasensor has a detection limit of 0.25nM thrombin. For clinical application of the developed aptasensor, thrombin levels in blood and cerebrospinal fluid (CSF) samples obtained from patients with Multiple Sclerosis, Myastenia Gravis, Epilepsy, Parkinson, polyneuropathy and healthy donors were analyzed using both the aptasensor and commercial ELISA kit. The results showed that the proposed system is a promising candidate for clinical analysis of thrombin.

A GPIIb/IIIa bioreactor for specific treatment of immune thrombocytopenic purpura, an autoimmune disease. Preparation, in vitro characterization, and preliminary proof-of-concept animal studies.

Immune thrombocytopenic purpura (ITP) is an autoimmune disease that affects thousands of Americans each year. The resulting thrombocytopenia, which develops from destruction of platelets (PLT) by anti-PLT autoantibodies (APAb), is often associated with hemorrhagic complications. Existing therapies are not effective and are associated with significant morbidity. Recently, a new treatment modality using plasmapheresis with a Protein-A column has shown some clinical promise. Yet, although this method would remove the pathogenic APAb, it would also deplete protective antibodies, thereby weakening the body's self-defense system. Because about 80% of patients with ITP develop APAb against the GPIIb/IIIa antigens on PLT, a novel approach of attaching a GPIIb/IIIa-linked bioreactor with an extracorporeal circuit is suggested herein to achieve highly effective/specific APAb removal and overcome shortcomings of plasmapheresis in treating ITP. A hollow fiber-based bioreactor device was fabricated, and GPIIb/IIIa antigens were immobilized onto the inner lumens of the hollow fibers by using the epichlorohydrin activation method. An optimized bioreactor containing a loading of 1.63 mg GPIIb/IIIa/g fibers and adsorption capacity of 1.9 mg 7E3/g fibers was developed. Preliminary proof-of-concept investigation using a 7E3-induced thrombocytopenic rat model (which mimicked clinical ITP) was carried out. A complete (100%) return of PLT counts to their initial levels was observed in rats within 6 h after the GPIIb/IIIa bioreactor treatment. In addition, a rapid restoration of WBC counts in the treated rats was also found. These preliminary findings shed light of promise of using the GPIIb/IIIa bioreactor approach in achieving highly improved ITP therapy.

Strategies for improving the functionality of an affinity bioreactor.

Heparin employed in extracorporeal blood circulation (ECBC) procedures (e.g. open heart operations) often leads to a high incidence of bleeding complications. Protamine employed in heparin neutralization, on the other hand, can cause severe adverse reactions. We previously developed an approach that could prevent both heparin- and protamine-induced toxic side effects concomitantly. This approach consisted of placing a hollow fiber-based bioreactor device containing immobilized protamine (termed a "protamine bioreactor") at the distal end of the ECBC procedure. This protamine bioreactor would remove heparin after heparin served its anticoagulant purpose in the ECBC device, thereby eliminating heparin-induced bleeding risks. In addition, this protamine bioreactor would prevent protamine from entering the patients, thereby aborting any protamine-induced toxic effects. Both in vitro and in vivo studies have successfully demonstrated the feasibility of this approach. Despite promises, early findings also revealed two shortcomings that must be overcome for the protamine bioreactor to be applied clinically. The first drawback was that the cyanate ester linkages, involved in conjugating protamine to the bioreactor device, were unstable and prone to hydrolysis, resulting in the leakage of a significant amount of protamine into circulation during application of the protamine bioreactor. The second deficiency was that the capacity of the protamine bioreactor in heparin removal was rather low, owing to the limited surface area of the hollow fibers for protamine immobilization and subsequently heparin adsorption. In this paper, we present novel strategies to overcome these two limitations. A new conjugation method based on the use of 4-(oxyacetyl)phenoxyacetic acid (OAPA) as the activating reagent was employed to yield stable linkages, via the abundant arginine residues of protamine, onto the hollow fibers. Results showed that while the amount of protamine immobilized on each gram of fibers was relatively comparable between the OAPA and the previous CNBr activation methods (7.45 mg/g versus 7.69 mg/g fibers), there was virtually no detectable leaching of immobilized protamine from the bioreactor by the OAPA method, comparing to 35% leaching of protamine by the previous CNBr method following 72 h of storage of the bioreactor in PBS buffer at 37 degrees C. To improve the capacity and functionality of the protamine bioreactor, two novel approaches were adopted. Long chain and high molecular weight poly-lysine was linked to the hollow fibers, prior to protamine coupling, to create multiple layers of immobilized protamine for subsequent heparin adsorption. In addition, a poly(ethylene glycol) (PEG) chain was inserted between protamine and the hollow fibers to yield a three-dimensional, free dynamic motion for immobilized protamine. Preliminary observations indicated that a four- to five-fold enhancement in heparin adsorption was attained by utilizing each of these new approaches. Aside from their current use, these new strategies can also be employed generically to improve the functionality of any affinity-type bioreactor. Indeed, efforts have been made recently in utilizing these approaches to develop a clinically usable GPIIb/IIIa bioreactor for the treatment of immune thrombocytopenic purpura (ITP)-an autoimmune disease.

Copper-zinc alloy nanoparticle based enzyme-free superoxide radical sensing on a screen-printed electrode.

In this paper, amperometric enzyme-free sensors using superoxide dismutase (SOD) enzyme as a catalyst for the dismutation reaction of superoxides into oxygen and hydrogen peroxide, enabling superoxide radical detection have been described. For this purpose, the surfaces of screen-printed platinum electrodes have been modified with gelatin composites of CuO, ZnO and CuZn nanoparticles with the expectation of an increase in catalytic effect toward the dismutation reaction. SOD containing electrodes were also prepared for comparative studies in which glutaraldehyde was used as a cross-linker for the immobilization of SOD to the nanocomposite materials. Electrochemical measurements were carried out using a screen-printed electrochemical system that included potassiumferrocyanide (K4[Fe(CN)6]) and potassiumferricyanide (K3[Fe(CN)6]) as the redox probes. The results revealed that the enzyme-free detection method using CuZn nanoparticles can determine superoxide radicals with high performance compared to other detection methods prepared with different nanoparticles by mimicking the active region of superoxide dismutase enzyme. The anodic (ks(a)) and cathodic (ks(c)) electron transfer rate constants and the anodic (α(a)) and cathodic (α(c)) transfer coefficients were evaluated and found to be ks(a)=6.31 s(-1) and α(a)=0.81, ks(c)=1.48 s(-1) and α(c)=0.19 for the gelatin-CuZn-SOD electrode; ks(a)=6.15 s(-1) and α(a)=0.79, ks(c)=1,63 s(-1) and α(c)=0.21 for the enzyme-free gelatin-CuZn electrode. The enzyme-free electrode showed nearly 80% amperometric performance with respect to the enzyme containing electrode indicating the superior functionality of enzyme-free electrode for the detection of superoxide radicals.

Evaluation of protein immobilization capacity on various carbon nanotube embedded hydrogel biomaterials.

This study investigates effective immobilization of proteins, an important procedure in many fields of bioengineering and medicine, using various biomaterials. Gelatin, alginate and chitosan were chosen as polymeric carriers, and applied in both their composites and nanocomposite forms in combination with carbon nanotubes (CNTs). The prepared nano/composite structures were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TG) and contact angle analysis (CA). Electrochemical impedance spectroscopy analysis revealed gelatin composites in general to exhibit better immobilization performance relative to the native gelatin which can be attributed to enhanced film morphologies of the composite structures. Moreover, superior immobilization efficiencies were obtained with the addition of carbon nanotubes, due to their conducting and surface enhancement features, especially in the gelatin-chitosan structures due to the presence of structural active groups.