A real time detection of the ovarian tumor associated antigen 1 (OVTA 1) in human serum by quartz crystal microbalance immobilized with anti-OVTA 1 polyclonal chicken IgY antibodies

In this study, we developed a sensitive quartz crystal microbalance (QCM) sensor which employs the anti-ovarian tumor associated antigen 1 (OVTA 1) IgY polyclonal chicken antibodies on the crystal surface for the detection of OVTA 1 in human serum. The anti-OVTA 1 IgY antibodies were anchored on the thiol-activated sensor surface using 1-ethyl-3[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC–NHS) coupling. The responses for different concentrations of anti-OVTA 1 antibody were also studied and 40 μg/mL was favorable for homogenous antibody coverage. The QCM sensor was used to monitor both immobilization and the target binding affinity. The anti-OVTA 1 antibody based QCM has allowed the competent detection of OVTA 1 in a high linear range of 0.5–10 μg/mL. The total time needed to complete the detection was as short as 5–6 h. The regeneration studies demonstrated that the proposed sensor was reusable up to 9 cycles with a slight loss in binding affinity. The detection of OVTA 1 in human serum allows a potential exploitation of the anti-OVTA 1 polyclonal antibody based QCM immunoassay for the screening of OVTA 1 antigen.     

From ultratough artificial nacre to elastomer: Poly(n-butyl acrylate) grafted graphene oxide nanocomposites

A biologically inspired, multilayer laminate structural design is deployed into composite films of poly(n-butyl acrylate) (PBA) graft graphene oxide (GO) synthesized by Ce(IV)/HNO₃ redox system in aqueous solution. Artificial hybrid films are fabricated by vacuum-assisted filtration macroscopic assembly method. Using nacre as the brick-and-mortar model construct free-standing membranes, here GO is similar to brick and PBA acts as mortar revealing the similar function of biopolymers in the natural nacre. Owing to the low T_g of PBA, the polymer chains could move freely at room temperature, enhancing the extensibility and flexibility. Meanwhile, the chemical structure of free-standing membranes was studied by Raman spectrum and XPS. The morphologies were charactered by XRD, SEM and TEM which are compact with the mechanical properties of the films. Interestingly, by tuning grafted PBA contents from 3.5 wt% to 77 wt%, quite wide range of mechanical properties (tensile strength from 20 to 180 MPa, Young’s modulus from 0.1 to 7 GPa, toughness from 0.8 to 4.3 MJ/m³, elongation from 1.2 to 24.5%) were obtained. At the same time, we found that the nanocomposite membranes can be adjusted from mimic nacre-liked film with high strength to a homogenous dispersed elastomer.     

Preparation,characterization and cytocompatibility of bioactive coatings on porous calcium-silicate-hydrate scaffolds

The major goal of this research was to investigate and characterize the deposition of a biomimetic apatite-like coating onto the surface of 3D porous calcium-silicate-hydrate scaffolds with suitable bioactivity for potential application in bone tissue engineering. Basically, Portland cement, water, sand and lime were mixed for preparing the slurry which was poured into molds, and fine aluminum powder was added as foaming agent resulting on the formation of porous 3D structures. After aging for 28 days, these porous inorganic scaffolds were immersed in calcium chloride supersaturated solution in PBS for 7 days at 37 °C for the biomimetic layer deposition. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR) techniques were used in order to characterize the porous scaffolds and the apatite-like biomimetic coating. The results have showed that 3D constructs were successfully produced with interconnected porosity, compressive strength and cytocompatibility appropriate for potential use as an alternative in trabecular bone repair.     

Reduction of Cr(VI) facilitated by biogenetic jarosite and analysis of its influencing factors with response surface methodology

In this paper, the facilitating role of biogenetic jarosite in the reduction of Cr(VI) by sulfide and its mechanism were investigated through batch experiments and analysis of X-ray photoelectron spectrum (XPS). To study the effects of operational parameters on the reduction of Cr(VI) by sulfide, four operational parameters (pH of solution, operation temperature, loading of jarosite and reaction time) were considered as input variables for response surface methodology (RSM). Graphical response surfaces and contour plots were used to evaluate the effect of interaction between operational parameters on the reduction of Cr(VI). The results suggest that a cycle process of converting Fe(III) to Fe(II) occurred on the surface of jarosite and markedly accelerated the reduction of Cr(VI) by sulfide. For example, the efficiency of Cr(VI) reduced by sulfide increased from 20.5% to 100% when jarosite (1 g/L) was added to the homogenous reaction system at pH = 8 within 40 min. The analysis of variance (ANOVA) revealed a high coefficient of determination (p-value < 0.0001, R² = 97.99%, Adj-R² = 95.98%) between experimental Cr(VI) removal efficiency and predicted one by RSM developed model. The Pareto analysis results demonstrated that the pH of solution was the most significant term of the developed model. Operation temperature, loading of jarosite and reaction time exhibited synergistic effects on the reduction of Cr(VI), and the effect of interaction between independent factors on the response factor can't be ignored.     

Synthesis of Ti-containing MCM41 using Ti(SO4)2 as Ti source

A simple and economic method was developed to synthesize Ti-containing MCM41 from titanium sulphate as Ti source, sodium metasilicate as Si source and cetyltrimethylammonium bromide (CTABr) as template. The resultant materials were characterized by using XRD, FT–IR, N₂ adsorption isotherms, HRTEM, ICP, and LRS techniques. It was revealed that the atoms of titanium were incorporated into the framework of MCM41 for the samples with Ti / Si mol ratios below 1 / 20. Small amount of titanium oxides that highly dispersed onto the wall of MCM41 were detected while the Ti / Si mol ratios up to 1 / 10. The prepared materials exhibited high catalytic activity in the oxidation of aromatic compounds.     

Site-specific Eu(III) binding affinities to a Datura innoxia biosorbent

The binding of Eu(III) to a biosorbent derived from cultured cells of the plant Datura innoxia, have been investigated through elucidation of apparent affinity constants associated with different chemical environments present on the cell wall. Adsorption isotherms for separate types of binding sites were generated using metal ion luminescence measurements. Application of regularized regression analysis to these isotherm data for four chemically distinguishable sites revealed the presence of sites exhibiting both low (mean log K_app = ?0.3 to 0.6) and higher (mean log K_app = 3.2–3.5) apparent affinities for pH conditions of 2.0, 4.0, and 5.0. Low affinity sites were observed for all pH conditions and attributed to non-specific binding of the metal ions to the negatively charged biomaterial. The pH-dependent higher affinity sites are ascribed to specific sites involving either an ion-exchange mechanism or formation of weak surface–metal ion complexes. These results differed significantly from a similar analysis of total metal binding isotherms that indicated mean log K_app values of ?0.5 to 0.25 (low affinity) and 5.6–6.0 (high affinity).     

Effects of poly(oxyethylene)-block structure in polyetheramines on the modified carbon nanotube/poly(lactic acid) composites

The hybrids of multi-walled carbon nanotube and poly(lactic acid) (MWCNT/PLA) were prepared by a melt-blending method. In order to enhance the compatibility between the PLA and MWCNTs, the surface of the MWCNTs was covalently modified by Jeffamine® polyetheramines by functionalizing MWCNTs with carboxylic groups. Different molecular weights and hydrophilicity of the polyethermaines were grafted onto MWCNTs with the assistance of a dehydrating agent. The results showed that low-molecular-weight Jeffamine® polyetheramine modified MWCNTs can effectively improve the thermal properties of PLA composites. On the other hand, high-molecular-weight and poly(oxyethylene)-segmented polyetheramine could render the modified MWCNTs of well dispersion in PLA, and consequently affecting the improvements of mechanical properties and conductivity of composite materials. With the addition of 3.0 wt% MWCNTs, the increment of E′ of the composite at 40 °C was 79%. For conductivity, the surface resistivity decreased from 1.27 × 10¹² Ω/sq for neat PLA to 8.30 × 10⁻³ Ω/sq for the composites.     

Effects of graphite shape on thermal fatigue resistance of cast iron with biomimetic non-smooth surface

In order to improve thermal fatigue resistance of cast iron and further study the effects of graphite shape on it, samples with different graphite shapes were processed by laser to create a biomimetic non-smooth surface. The results indicated that laser processed zone caused the longer crack initiation life and the slower crack propagation rate, which endowed biomimetic non-smooth surface with a beneficial effect on improving thermal fatigue behavior of iron with flake, vermiform or nodular graphite. Thermal fatigue resistance of samples with the same kind of surface (smooth or non-smooth) all were sorted as nodular graphite iron > vermicular graphite iron > flake graphite iron.     

Towards development of colorimetric test-systems for phenols detection based on computationally-designed molecularly imprinted polymer membranes

Colorimetric test-system for the express-control of phenols content in water was developed. The system consisted of free-standing molecularly imprinted polymer (MIP) membranes which contained synthetic binding sites capable of phenol binding. The MIP membranes were obtained by co-polymerisation of a functional monomer (e.g. itaconic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylamide or methacrylic acid) with triethyleneglycoldimethacrylate and oligourethaneacrylate. Rational choice of the functional monomers was based on the results of computational modelling. The phenol-selective MIP membranes were used as a basis for the colorimetric test-system for measuring phenol in aqueous samples. Phenol molecules were selectively adsorbed by the MIP membranes and quantified using color reaction with 4-aminoantipyrine. The intensity of the membranes' staining was proportional to the phenol concentration in the analysed sample. The optimised colorimetric test-system based on MIP membranes demonstrated a low detection limit (50 nM), a wide working range — 50 nM–0.5 mM and an excellent storage stability at room temperature (12 months). As compared to the traditional methods of phenols detection the developed test-system is superior because of simplicity of operation, small size and low cost.     

Properties and thermal stability of solution processed ultrathin,high-k bismuth titanate (Bi2Ti2O7) films

Ultrathin bismuth titanate films (Bi₂Ti₂O₇, 5–25 nm) are deposited onto SiO₂/Si substrates by aqueous chemical solution deposition and their evolution during annealing is studied. The films crystallize into a preferentially oriented, pure pyrochlore phase between 500 and 700 °C, depending on the film thickness and the total thermal budget. Crystallization causes a strong increase of surface roughness compared to amorphous films. An increase of the interfacial layer thickness is observed after anneal at 600 °C, together with intermixing of bismuth with the substrate as shown by TEM-EDX. The band gap was determined to be ～3 eV from photoconductivity measurements and high dielectric constants between 30 and 130 were determined from capacitance voltage measurements, depending on the processing conditions.     

Silk fibroin immobilization on poly(ethylene terephthalate) films: Comparison of two surface modification methods and their effect on mesenchymal stem cells culture

Silk fibroin (SF) has played a curial role for the surface modification of conventional materials to improve the biocompatibility, and SF modified poly(ethylene terephthalate) (PET) materials have potential applications on tissue engineering such as artificial ligament, artificial vessel, artificial heart valve sewing cuffs dacron and surgical mesh engineering. In this work, SF was immobilized onto PET film via two different methods: 1) plasma pretreatment followed by SF dip coating (PET-SF) and 2) plasma-induce acrylic acid graft polymerization and subsequent covalent immobilization of SF on PET film (PET-PAA-SF). It could be found that plasma treatment provided higher surface roughness which was suitable for further SF dip coating, while grafted poly(acrylic acid) (PAA) promised the covalent bonding between SF and PAA. ATR-FTIR adsorption band at 3284 cm^? 1, 1623 cm^? 1 and 1520 cm^? 1 suggested the successful introduction of SF onto PET surface, while the amount of immobilized SF of PET-SF was higher than PET-PAA-SF according to XPS investigation (0.29 vs 0.23 for N/C ratio). Surface modified PET film was used as substrate for mesenchymal stem cells (MSCs) culture, the cells on PET-SF surface exhibited optimum density compared to PET-PAA-SF according to CCK-8 assays, which indicated that plasma pretreatment followed by SF dip coating was a simple and effective way to prepare biocompatible PET surface.     

Biomimetic mineralisation of apatites on Ca2+ activated cellulose templates

We investigated the activation of regenerated cellulose 2D model thin films and 3D fabric templates with calcium dihydroxide. The Langmuir–Blodgett (LB) film technique was applied for manufacturing of the model thin films using a trimethylsilyl derivative of cellulose (TMS-cellulose). Regenerated cellulose films were obtained by treating the TMS-cellulose LB-films with hydrochloric acid vapours. For 3D templates, regenerated cellulose fabrics (Lyocell®) were used. The regenerated cellulose templates were activated with a Ca(OH)₂-suspension and subsequently exposed to 1.5 × SBF to induce the in situ formation of biomimetic calcium phosphate phases. FTIR and Raman spectroscopy showed that the Ca(OH)₂ and calcite present from reaction with HCO₃⁻ on the template surface were dissolved in the initial stage of exposure to the 1.5 × SBF. After 1 day, the formation of apatitic phases in 1.5 × SBF was observed. According to detailed calculations, high supersaturation levels S in close vicinity to the template surface (S > 16) resulting from the Ca²⁺ diffusion induced the formation of biomimetic calcium phosphate. The biomimetic calcium phosphates were identified by FTIR and Raman spectroscopy as highly carbonated apatites (HCA) lacking hydroxyl ions. 3D fabric templates of regenerated cellulose covered with a biomimetic coating of apatite might be of particular interest for novel scaffold architectures in bone repair and tissue engineering.     

Ligand exchange based paraoxon imprınted QCM sensor

In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal–chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K_affinity) were found to be 0.06 μM and 2.25 × 10⁴ M^? 1 for paraoxon [MAAP–Cu(II)–paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.     

Impact of functional monomers,cross-linkers and porogens on morphology and recognition properties of 2-(3,4-dimethoxyphenyl)ethylamine imprinted polymers

The main objective of this paper was to examined the impact of synthetic reagents on morphology and recognition properties of 2-(3,4-dimethoxyphenyl)ethylamine imprinted polymers. The effect of nine different functional monomers, five porogens and four cross-linkers on the binding capacity of particles was analyzed. The results revealed that the highest imprinting factor (1.81) showed the polymer obtained from methacrylic acid and ethylene glycol dimethacrylate in toluene. The binding capacities of imprinted (MIP1) and non-imprinted (NIP1) materials were 135.3 ± 9.8 and 74.8 ± 7.8 μmol g^? 1, respectively. The specific surface areas were 55.05 ± 3.89 for MIP1 and 38.72 ± 2.40 m² g^? 1 for NIP1. The SEM analysis confirmed that the surface of MIP1 is rougher and denser than NIP1. Structural analysis supported by ¹³C CP/MAS NMR spectra was also performed. The binding abilities of homoveratrylamine and eight structurally related compounds to MIP1 showed that strong interactions between carboxylic group in the polymer and amine group in the analyte together with its molecular volume govern the recognition mechanism.     

Room temperature deposition of IZTO transparent anode films for organic light-emitting diodes

This study was to investigate anodic electrode IZTO films deposited by pulsed DC magnetron sputter at room temperature with various oxygen partial pressures onto glass substrate and to analyze the structural, electrical, and optical properties, as well as the relationship between the chemical binding state of the surface and the characteristics of IZTO films. In addition, the prepared IZTO films were used to fabricate the organic light emitting diodes (OLEDs) as an anode layer to study the device performances. The IZTO film deposited at optimal oxygen partial pressure of 2.0% in sputtering process showed the best properties, such as a low electrical resistivity and high optical transmittance of <5.1 × 10^?4 Ω cm and >80% in the visible wavelength of 400–800 nm, respectively. The OLED characteristics with the optimum condition showed good brightness and the lowest turn-on voltage of >10,000 cd/m² and 4.67 V. These results indicate that IZTO films can be a promising candidate as an alternative TCO electrode material for flexible and OLED devices.     

Modified gold surfaces by 6-(ferrocenyl)hexanethiol/dendrimer/gold nanoparticles as a platform for the mediated biosensing applications

An electrochemical biosensor mediated by using 6-(Ferrocenyl) hexanethiol (FcSH) was fabricated by construction of gold nanoparticles (AuNPs) on the surface of polyamidoamine dendrimer (PAMAM) modified gold electrode. Glucose oxidase (GOx) was used as a model enzyme and was immobilized onto the gold surface forming a self assembled monolayer via FcSH and cysteamine. Cyclic voltammetry and amperometry were used for the characterization of electrochemical response towards glucose substrate. Following the optimization of medium pH, enzyme loading, AuNP and FcSH amount, the linear range for the glucose was studied and found as 1.0 to 5.0 mM with the detection limit (LOD) of 0.6 mM according to S/N = 3. Finally, the proposed Au/AuNP/(FcSH + Cyst)/PAMAM/GOx biosensor was successfully applied for the glucose analysis in beverages, and the results were compared with those obtained by HPLC.     

Preparation and characterization of bimodal porous poly(γ-benzyl-L-glutamate) scaffolds for bone tissue engineering

An ideal scaffold in bone tissue-engineering strategy should provide biomimetic extracellular matrix-like architecture and biological properties. Poly(γ-benzyl-L-glutamate) (PBLG) has been a popular model polypeptide for various potential biomedical applications due to its good biocompatibility and biodegradability. This study developed novel bimodal porous PBLG polypeptide scaffolds via a combination of biotemplating method and in situ ring-opening polymerization of γ-benzyl-L-gIutamate N-carboxyanhydride (BLG-NCA). The PBLG scaffolds were characterized by proton nuclear magnetic resonance spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscope (SEM) and mechanical test. The results showed that the semi-crystalline PBLG scaffolds exhibited an anisotropic porous structure composed of honeycomb-like channels (100–200 μm in diameter) and micropores (5–20 μm), with a very high porosity of 97.4 ± 1.6%. The compressive modulus and glass transition temperature were 402.8 ± 20.6 kPa and 20.2 °C, respectively. The in vitro biocompatibility evaluation with MC3T3-E1 cells using SEM, fluorescent staining and MTT assay revealed that the PBLG scaffolds had good biocompatibility and favored cell attachment, spread and proliferation. Therefore, the bimodal porous polypeptide scaffolds are promising for bone tissue engineering.     

Fabrication,characterization and application of pectin degrading Fe3O4–SiO2 nanobiocatalyst

The covalent binding of pectinase onto amino functionalized silica-coated magnetic nanoparticles (CSMNPs) through glutaraldehyde activation was investigated for nanobiocatalyst fabrication. The average particle size and morphology of the nanoparticles were characterized using transmission electron microscopy (TEM). The statistical analysis for TEM image suggests that the coating and binding process did not cause any significant change in size of MNPs. The morphological and phase change of the magnetic nanoparticles (MNPs) after various coatings and immobilization were characterized by X-ray diffraction (XRD) studies. The various surface modifications and pectinase binding onto nanoparticles were confirmed by Fourier transform infrared (FT-IR) spectroscopy. The maximum activity of immobilized pectinase was obtained at its weight ratio of 19.0 × 10^? 3 mg bound pectinase/mg CSMNPs. The pH, temperature, reusability, storage ability and kinetic studies were established to monitor their improved stability and activity of the fabricated nanobiocatalyst. Furthermore, the application was extended in the clarification of Malus domestica juice.     

Studies on polymer electrolyte poly(vinyl) pyrrolidone (PVP) complexed with ionic liquid: Effect of complexation on thermal stability,conductivity and relaxation behaviour

Polymer electrolyte films of PVP + x wt% ionic liquid (IL) (1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF₄]) for x = 0, 5, 10, 15, 20, 25 wt% have been prepared using solution cast technique. These films were characterized by TGA, DSC, FT-IR and ac impedance spectroscopy techniques. From XRD studies it is found that the inclusion of IL increases the amorphocity of polymeric membranes. DSC thermograms show that the glass transition (T_g) and melting temperatures (T_m) of PVP shift upon complexation with IL. FT-IR analysis shows the complexation of PVP with IL. Thermogravimetric studies show that PVP decomposes in a single step while PVP/IL membranes exhibit two step decomposition; lower value of decomposition temperature corresponds to the decomposition of PVP/IL complex while the higher decomposition temperature has been attributed to the decomposition of PVP. The decomposition temperature of PVP/IL complex decreases with the increasing amount of IL in the PVP membrane. Temperature dependence of conductivity and dielectric relaxation frequencies have also been studied for PVP and PVP/IL membranes. Both show thermally activated Arrhenius behaviour.     

Removal and preconcentration of lead (II), copper (II), chromium (III) and iron (III) from wastewaters by surface developed alumina adsorbents with immobilized 1-nitroso-2-naphthol

The potential removal and preconcentration of lead (II), copper (II), chromium (III) and iron (III) from wastewaters were investigated and explored. Three new alumina adsorbents of acidic, neutral and basic nature (I–III) were synthesized via physical adsorption and surface loading of 1-nitroso-2-naphthol as a possible chelating ion-exchanger. The modified alumina adsorbents are characterized by strong thermal stability as well as resistance to acidic medium leaching processes. High metal up-take was found providing this order: Cu(II) > Cr(III) > Pb(II) owing to the strong contribution of surface loaded 1-nitroso-2-naphthol. The outlined results from the distribution coefficient and separation factor evaluations (low metal ion concentration levels) were found to denote to a different selectivity order: Pb(II) > Cu(II) > Cr(III)) due to the strong contribution of alumina matrix in the metal binding processes. The potential applications of alumina adsorbents for removal and preconcentration of Pb(II), Cu(II), Cr(III) from wastewaters as well as drinking tap water samples were successfully accomplished giving recovery values of (89–100 ± 1–3%) and (93–99 ± 3–4%), respectively without any noticeable interference of the wastewater or drinking tap water matrices.