Characterization of immobilization methods of antiviral antibodies in serum for electrochemical biosensors

In this paper, we describes different methods to immobilize Japanese encephalitis virus (JEV) antibodies in human serum onto the interdigitated surface of a microelectrode sensor for optimizing electrochemical detection: (1) direct covalent binding to the silanized surface, (2) binding to the silanized surface via a cross-linker of glutaraldehyde (GA), (3) binding to glutaraldehyde/silanized surface via goat anti-human IgG polyclonal antibody and (4) binding to glutaraldehyde/silanized surface via protein A (PrA). Field emission scanning electron microscopy, Fourier transform infrared spectrometry, and fluorescence microscopy are used to verify the characteristics of antibodies on the interdigitated surface after the serum antibodies immobilization. The analyzed results indicate that the use of protein A is an effective choice for immobilization and orientation of antibodies in serum for electrochemical biosensors. This study provides an advantageous immobilization method of serum containing antiviral antibodies to develop electrochemical biosensors for preliminary screening of viruses in clinical samples from outbreaks.     

Self-assembly of silanated poly(ethylene glycol) on silicon and glass surfaces for improved haemocompatibility

Surface immobilization of poly(ethylene glycol) (PEG) is an effective method to produce a material surface with protein repulsive property. This property could be made permanent by using covalent grafting of the PEG molecules onto material surfaces. In this study, self-assembled monolayers (SAMs) of PEG on silicon-containing materials (silicon chip and glassplate) were obtained through a one-step coating procedure of one kind of silanated PEG molecules made through the reaction between monomethoxy PEG and 3-isocyanatopropyltriethoxysilane. Atomic force microscopy (AFM) and water static contact angle measurement were employed to investigate the surface topography and wettability of the PEGylated material surfaces. The changes in the topography and the water contact angle of the surfaces with time of incubation in PBS solution were also measured. The results revealed that stable and uniform self-assembled monolayers of PEG could be formed on silicon or glass surfaces by simply soaking the substrates in the solution of silanated PEGs. The covalent coupling of PEGs to the substrates was also confirmed. In order to evaluate the stability of the SAMs, blood compatibility of the modified glassplate surface was evaluated by measuring full blood activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT), as well as by scanning electron microscopy (SEM) analysis of the appearance of adherence and denaturation of blood platelets onto the glassplate. The silanated PEGs were shown to have good effect on the protein-repulsion as well as haemocompatibility of the substrates.     

Electron microscopic investigations of tracks of Cf252 fission fragments in quartz glass

Using a single stage carbon replication technique, track pits of Cf²⁵²-fission products in quartz glass could be revealed by transmission electron microscopy with a high degree of resolution. From the shape of the track pits the angles of incidence of the nuclear particles were determined down to extremely small angles. In addition track pits on the fracture surface of irradiated quartz glass samples have been investigated by scanning electron microscopy.     

Chemolabile cellular microarrays for screening small molecules and peptides

Microarrays that mediate the uptake of small molecules into living cells are described. Tissue culture cells were seeded onto glass substrates functionalized locally with fluorescently labelled test substances. In order to enable a localized transfer of substances after contact of cells with the substrate, substances were immobilized on the surface either by non-covalent interactions or chemolabile linker groups. These chemolabile linker groups were incorporated into covalently immobilized compounds. Different ester linkages were evaluated as chemolabile linker groups. As model compounds, esters of the carboxy group of a cysteine with the hydroxy groups of carboxyfluorescein-labelled serine amide and tyrosine amide residues or the thiol group of another fluorescein-labelled cysteine amide were generated. Covalent immobilization occurred on maleimide-functionalized glass cover slips. The surface functionalization and release kinetics were assessed by confocal laser scanning microscopy. The fastest release was obtained for the phenolic tyrosine ester. Alternatively, fluorescently labelled peptides were immobilized by non-covalent interactions on glass and on a hydrogel matrix. In order to increase the efficiency of cellular uptake, peptides were N-terminally extended with a cell-penetrating peptide. Uptake of these peptides into cells was confined to the functionalized spots, and was specific for peptides extended with the cell-penetrating peptide.     

载铅(Ⅱ)高硅质大气矿物细颗粒对大肠杆菌的毒性作用研究

以大气颗粒物中的高硅质矿物细颗粒--石英粉尘和重金属离子附载污染物Pb(Ⅱ)为实验材料,人工制备载铅石英粉尘。以1.6 g·L-1的载铅(Ⅱ)石英粉尘及不同浓度的PbCl₂染毒大肠杆菌细胞,观察染毒2 h后对机体的联合氧化损伤效应,并探讨其对大肠杆菌表面基团及蛋白酰胺I带二级结构的影响。结果表明,与Pb(Ⅱ)、载铅石英粉尘作用后,大肠杆菌细胞活力降低,胞内活性氧(ROS)及丙二醛(MDA)产生增多、谷胱甘肽(GSH)含量下降,引起细菌氧化应激水平的提高;皮尔逊(Pearson)相关性分析显示载铅石英粉尘的细菌毒性与粉尘中Pb(Ⅱ)可交换态含量成正相关,载带高浓度Pb(Ⅱ)的石英粉尘组胞内ROS/MDA水平与其单纯石英粉尘组和Pb(Ⅱ)组比较显著增加(p<0.05);重金属Pb(Ⅱ)、载铅石英粉尘对大肠杆菌菌体表面基团的影响主要集中于磷酸二酯基团和表面多糖分子,采用二阶导、去卷积和谱线拟合技术对酰胺Ⅰ带特征峰(1 600～1 700 cm-1)进行分峰拟合后发现,与Pb(Ⅱ)、载铅石英粉尘(Q-Pb-0,Q-Pb-3)作用后,β-sheets/α-helices的比值由对照组的1.41分别降低到1.33,1.27和1.22,表明细菌表面蛋白质结构发生了变化,从而可能影响了细菌的生理活动。研究表明自由基所产生的氧化损伤可能是载Pb(Ⅱ)石英粉尘的一种重要毒性作用机制,载带Pb(Ⅱ)的复合石英粉尘在致大肠杆菌机体氧化损伤效应方面二者存在一定的协同作用。     

Covalent immobilization of glucose oxidase onto Poly(St-GMA-NaSS) monodisperse microspheres via BSA as spacer arm

In this study, the immobilization of glucose oxidase (GOD) onto micron-size monodisperse Poly(Styrene-Glycidyl Methacrylate-Sodium Sulfonate Styrene) microspheres was investigated. In order to improve their surface biocompatibility, bovine serum albumin (BSA) was introduced onto the microspheres’ surface as a new type of spacer arm. Both the immobilization amount and enzymatic activity were determined in different experimental conditions (enzyme concentration, pH, temperature, etc.). It was found that BSA could serve as a good spacer because it increases both the immobilization amount and enzymatic activity of GOD. The tolerance of immobilized GOD against pH, temperatures was examined. Moreover, the kinetic parameters for native and immobilized GOD were obtained and compared.     

Growth of hydrogel nano- and microlayers covalently bounded onto PE surface

Surface modifying strategies were developed to immobilize PAA cross-linked layers (hydrogel layers) with different thicknesses by chemical binding to the surface of polyethylene (PE). Polyethylene films were functionalized by two methods, chromic acid oxidation and maleic anhydride grafting. The reaction of the functional groups placed onto the film surface with ethylenediamine promoted the formation of an amine-functionalized surface. The thickness of the hydrogel layer was correlated with the presence and the release of impregnated ethylenediamine during the immobilization of the PAA chains by thermal esterification. Ethylenediamine acts as a cross-linking agent between different PAA chains. Attenuated total reflectance (ATR) FTIR spectroscopy and scanning electron microscopy (SEM) were used to characterize the chemical composition and the morphologies of the modified film surface.     

Novel photonic technique creates micrometer resolution protein arrays and provides a new approach to coupling of genes, peptide hormones and drugs to nanoparticle carriers

We demonstrate that ultraviolet light can be used to make sterically oriented covalent immobilization of a large variety of protein molecules onto either thiolated quartz, gold or silicon. The reaction mechanism behind the reported new technology involves light-induced breakage of disulphide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol reactive surfaces. In general, the protein molecules retain their function. The size of the immobilization spot is limited to the focal point of illumination being as small as a few micrometers. This new technology allows for dense packing of different bio-molecules on a surface, allowing the creation of multi-potent functionalised new materials, such as nano-biosensors. We have developed the necessary technology for preparing large protein arrays of enzymes and fragments of monoclonal antibodies. Dedicated image processing software has been developed for making quality assessment of the protein arrays. This novel technology is ideal to couple drugs and other bio-molecules to nanoparticles which can be used as carriers into cells for therapeutic purposes.     

Synthesis,Spectroscopy and Photochemistry of Novel Branched Fluorescent Nitro-Stilbene Derivatives with Benzopheonone Groups

In this article, we presented novel nitro-stilbene derivatives with one or two benzophenone groups as photoinitiators via multi-steps synthesis. The ultraviolet/visible spectroscopy and the emission spectroscopy of the compounds were determined in various solvents. The results showed that the ultraviolet/visible absorption spectroscopy of the derivatives with benzophenone moiety displayed overlap effects of nitro-stilbene and benzophenone parts. In non-polar solvents, the derivatives exhibited strong emission, while they displayed weak emission in modest and strong polar solvents. Dyes-linked benzopheonone groups displayed stronger fluorescence emission than simple chromophore parent molecules. Visible-light photoinitiating effects of the derivatives were investigated extensively. Methyl methacrylate could be photoinitiated efficiently by the derivatives with benzophenone moieties at very low concentration, even at 1 × 10⁻⁵ mol/L. While the photopolymerization efficiency of styrene initiated by the derivatives was lower than that of methyl methacrylate. Our results showed that the dye-linked photoinitators had more efficient photoinitiating than the simple mixture of dye and photoinitator. Furthermore, the derivative with two benzophenone groups displayed more excellent phototiniatiating effects than the derivative with one benzophenone group. Thermodynamics driving for the occurrence of visible-light photoinduced intramolecular electron transfer from chromophore part to benzophenone part was evaluated. Benzopinacol moiety produced in photoreaction was confirmed by nuclear magnetic resonant spectroscopy. Thermal stability of the derivatives was analyzed.     

Tribological behavior of in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films

Multilayer polyelectrolyte films containing silver ions were obtained by molecular deposition method on a glass plate or a quartz substrate. The in situ Ag nanoparticles were synthesized in the multilayer polyelectrolyte films which were put into fresh NaBH₄ aqueous solution. The structure and surface morphology of composite molecular deposition films were observed by UV-vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Tribological characteristic was investigated by AFM and micro-tribometer. It was found that the in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films have lower coefficient of friction and higher anti-wear life than pure polyelectrolyte molecular deposition films.     

Influence of coupling agent chain lengths on interfacial performances of polyarylacetylene resin and silica glass composites

The influence of chain lengths on interfacial performances of polyarylacetylene (PAA)/silica glass composites was studied. In order to obtain different chain lengths on substrates, methyltrimethoxysilane, propyltrimethoxysilane, octyltrimethoxysilane and dodecyltrimethoxysilane were grafted onto silica glass surface. Topographies of silica glass surface and the wetting ability of PAA resin on silica glass surface were characterized by atomic force microscopy (AFM) and surface free energy along with contact angles, respectively. At the same time, the interfacial adhesion was evaluated by shear strength testing. The failure mechanisms of composites were also analyzed by fracture morphologies. The results of the study indicate that with chain lengths of coupling agents on silica glass surface increasing, interfacial shear strengths of PAA/silica glass composites increase, while the wetting ability of PAA resin on silica glass surface decreases. The main mechanism for the improvement of the interfacial adhesion is physical entanglement interaction between the chain of coupling agent and the chain of PAA resin.     

Deposition of carbon films using close space sublimation

Carbon films are fabricated for the first time using an inexpensive and ecologically safe modified method of close space sublimation at atmospheric pressure. They are deposited onto quartz, glass, glass ceramic (Pyroceram), and silicon substrates. The main properties of the films (such as the growth rate, morphology and structure, optical properties, the dependences of these properties on the deposition temperature and the substrate material) are studied by X-ray diffraction, atomic force microscopy, multiangular ellipsometry, and the measurement of transmission and reflectance spectra in the visible and near ultraviolet regions. The growth rate is 5 nm/min at a film nucleation temperature of 800°C. The film thickness varies from 0.2 to 2.2 μm, and the minimum surface roughness is 0.5 nm. The refractive indices of the films range from 1.3 to 1.8 depending on the growth and subsequent heat treatment conditions. The optical energy gap is 5.4 eV.     

光纤与生物分子界面上固定FITC标记抗体的荧光光谱

采用化学方法把FITC标记羊抗人抗体IgG共价固定到三氨基三乙氧基硅烷和戊二醛(APTES-Glu)修饰的石英光纤纤芯表面。通过研究未经过任何修饰的纤芯表面的吸附以及共价固定的FITC标记羊抗人抗体的荧光光谱性质发现:共价结合到纤芯表面的FITC荧光光谱相对于溶液中FITC的荧光峰位红移约9nm,而物理吸附的FITC的荧光峰位移动约4nm,而且两者相对荧光强度相差6倍。而在固定的人血清蛋白进行免疫反应后,FITC的荧光峰位只移动3～4nm,除此之外,研究了抗体共价键固定的稳定性问题。结果表明:共价键结合抗体的数量要大于表面吸附,共价键固定的FITC标记羊抗人抗体与光纤表面间的相互作用较吸附于光纤表面的FITC标记羊抗人抗体间的相互作用更强。这对于建立一种通过荧光光谱识别固体表面与生物分子的吸附还是共价结合的判据提供了物理基础。     

Laser spectroscopic investigation of a new precursor-type polyparaphenylenevinylene

Optical, structural and morphological properties of thin films of polyparaphenylenevinylene (PPV) formed by an alkyl sulfinyl precursor route have been studied. Thin films were fabricated on an optical glass and on quartz glass either by spin-coating of the precursor solution or by layer-by-layer deposition using Langmuir–Blodgett technique. PPV precursor films were also spin-coated on gold-coated glass in order to study thin-film optical parameters by surface plasmon spectroscopy. We have been successful in forming about 40 precursor mono layers on quartz glass by Langmuir–Blodgett technique using optimized surface pressure and dipping conditions. After thermal conversion of the precursor layers good quality fluorescent PPV films of yellow colour have been obtained. Optical characterization of the films was carried out by linear absorption and emission spectroscopy, ellipsometry, and surface plasmon spectroscopy. Structural and morphological studies on the thin films were carried out by using X-ray scattering and atomic force microscopy. Wave-guided travelling-wave laser action has been achieved in a PPV film on quartz glass. The sample was transversally pumped with picosecond laser pulses (wavelength 347.15 nm, duration 35 ps). Laser emission occurred at 550 nm for pump pulse energy densities above .     

Growth of Al–N codoped p-type ZnMgO thin films on different substrates

Al–N codoped p-type ZnMgO thin films were prepared on three different substrates, namely glass, quartz, and silicon. Significant differences in the crystallinity, surface morphology, and electrical properties on these substrates were investigated by means of x-ray diffraction, field-emission scanning electron microscopy, and Hall-effect measurements. It is demonstrated that the Al donor enhances the incorporation of the N acceptor, resulting in better p-type conductivity. The incorporation of the N acceptor, as well as the Al and Mg, was confirmed x-ray photoelectron spectroscopy. Transmittance and photoluminescence spectra suggested a wider bandgap for the ZnMgO thin films in comparison with ZnO, which is believed to be the result of the incorporation of Mg.     

Preparation of silver-coated glass frit and its application in silicon solar cells

A simple electroless plating process was employed to prepare silver-coated glass frits for solar cells. The surface of the glass frits was modified with polyvinyl-pyrrolidone(PVP) before the electroless plating process. Infrared(IR) spectroscopy,field emission scanning electron microscopy(FESEM), and x-ray diffraction(XRD) were used to characterize the PVP modified glass frits and investigate the mechanism of the modification process. It was found that the PVP molecules adsorbed on the glass frit surface and reduced the silver ions to the silver nanoparticles. Through epitaxial growth, these nanoparticles were uniformly deposited onto the surface of the glass frit. Silicon solar cells with this novel silver coating exhibited a photoelectric conversion efficiency increase of 0.33%. Compared with the electroless plating processes, this method provides a simple route to prepare silver-coated glass frits without introducing impurity ions.     

Surface modification on a glass surface with a combination technique of sol-gel and air brushing processes

This study fabricated the large area and optically transparent superhydrophobic silica based films on glass surface with optimized hardness. A silane coupling agent, tetraethoxysilane (TEOS), effectively bonds silica particles onto the glass substrate. Desired surface roughness was obtained by adjusting nano silica particles concentration of the precursors prepared by the sol-gel process. Silica suspension was coated onto the glass substrate by the air brushing methods. This method can deposit a uniform, transparent coating on the glass substrate efficiently. Diluting the precursor by adding ethanol or a mixture of D.I. water and ethanol further improved the transmittance and superhydrophobicity efficiency. The results showed that as the silica particle concentration and the thickness of the coating were increased, the surface roughness was enhanced. Rougher surface displayed a higher superhydrophobicity and lower transmittance. Therefore, the concentration of silica particle, volume of coatings, and the ratio of ethanol and D.I. water are of great importance to deposit a transparent, superhydrophobic coating on glass.     

Surface modification of ultra high molecular weight polyethylene fibers via the sequential photoinduced graft polymerization

In this study, a sequential photoinduced graft polymerization process was proposed to improve the poor interfacial bonding property of ultra high molecular weight polyethylene (UHMWPE) fibers. The polymerization was initiated by dormant semipinacol (SP) groups and carried out in a thin liquid layer. Methacrylic acid (MAA) and acryl amide (AM) were grafted stepwise onto the surface of UHMWPE fibers. Attenuated total reflectance infrared spectroscopy (ATR-IR) and thermo gravimetric analysis (TGA) confirmed the grafting. The analysis result of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) indicated the structure of grafted chains. Scanning electron microscopy (SEM) images and atomic force microscopy (AFM) images revealed the apparent morphology changing, and the grafted layers were observed. Interfacial shear stress (IFSS) test of the modified fibers showed an extensively improved interfacial bonding property. The active groups grafted onto the fibers would supply enough anchor points for the chemical bonding with various resins or further reactions.     

Use of quartz crystal nanobalance to study the binding and stabilization of albumin and doxycycline on a thin layer of hydroxyapatite

This study reports the use of quartz crystal nanobalance (QCN) to study the adsorption of two model molecules namely albumin and doxycycline by hydroxyapatite (HA). The work focuses on the deposition of a stable coating of HA on the quartz crystal, modification of the coating using doxycycline and its subsequent effects on albumin adsorption. The uniformity and thickness of the HA coating has been studied using atomic force microscopy (AFM). The functional groups to ascertain the presence of the selected moieties have been characterized by Raman spectroscopy. The results indicate that the mass of albumin deposited on the surface of the HA coated quartz crystal functionalized with doxycycline shows a substantial increase when compared to the standard HA coated quartz crystal. The adsorbed albumin has also been found to be retained for an enhanced period of time. This surface immobilization of doxycycline and subsequent albumin adsorption seem to be a promising approach to confer biomaterials with antithrombogenic and antibacterial surfaces.     

Raman spectroscopy analysis of structural photoinduced changes in GeS2 + Ga2O3 thin films

Photoexpansion and photobleaching effects have been observed in amorphous GeS₂ + Ga₂O₃ (GGSO) thin films, when their surfaces were exposed to UV light. The photoinduced changes on the surface of the samples are indications that the structure has been changed as a result of photoexcitation. In this paper, micro-Raman, energy dispersive X-ray analysis (EDX) and backscattering electrons (BSE) microscopy were the techniques used to identify the origin of these effects. Raman spectra revealed that these phenomena are a consequence of the Ge–S bonds’ breakdown and the formation of new Ge–O bonds, with an increase of the modes associated with Ge–O–Ge bonds and mixed oxysulphide tetrahedral units (S–Ge–O). The chemical composition measured by EDX and BSE microscopy images indicated that the irradiated area is oxygen rich. So, the present paper provides fundamental insights into the influence of the oxygen within the glass matrix on the considered photoinduced effects.