Size-modulated catalytic activity of enzyme-nanoparticle conjugates: a combined kinetic and theoretical study

A series of experiments were performed to systematically analyze the effect of nanoparticle (NP) size on the catalytic behavior of enzyme-NP conjugates, and a shielding model based on diffusion-collision theory was developed to explain the correlation between the size effects and the kinetic responses.     

Evidence of multiple pathways capable of emitting peroxyoxalate chemiluminescence using a charge coupled device spectrometer

Peroxyoxalate chemiluminescence (PO-CL) spectra obtained simultaneously and continuously using a CCD spectrometer provide evidence of the complexity of PO-CL reactions.     

Non-aqueous approach to the preparation of reduced graphene oxide/α-Ni(OH)2 hybrid composites and their high capacitance behavior

Reduced graphene oxide/α-Ni(OH)(2) composites present high electrochemical properties, with specific capacitance of 1215 F g(-1) at 5 mV s(-1) scan rate, since graphene as conductive matrix provides electronic conduction pathway.     

Synthesis of annulated thiophene perylene bisimide analogues: their applications to bulk heterojunction organic solar cells

Annulated thiophene perylene bisimides and their triphenyl-amine based oligomers have been synthesized. One of the oligomers FPTTPA has been demonstrated to be an efficient electron donor in bulk heterojunction (BHJ) organic solar cells, giving a power conversion efficiency of 1.42%.     

Zebrafish as a good vertebrate model for molecular imaging using fluorescent probes

Fluorescent probes have been used extensively to monitor biomolecules and biologically relevant species in vitro and in vivo. A new trend in this area that has been stimulated by the desire to obtain more detailed information about the biological effects of analytes is the change from live cell to whole animal fluorescent imaging. Zebrafish has received great attention for live vertebrate imaging due to several noticeable advantages. In this tutorial review, recent advances in live zebrafish imaging using fluorescent probes, such as fluorescent proteins, synthetic fluorescent dyes and quantum dots, are highlighted.     

Albumin adsorption on unmodified and sulfonated polystyrene surfaces, in relation to cell-substratum adhesion

Albumin is commonly applied for blocking the adsorption of other proteins and to prevent the nonspecific adhesion of cells to diverse artificial substrata. Here we address the question of how effective these albumin properties are--by investigating unmodified and sulfonated polystyrene substrata with distinctly different wettabilities. As clearly shown with (125)I-radioisotopic assays, above a concentration of 10-20 μg/mL, the efficiency of bovine serum albumin (BSA) adsorption became markedly higher on the sulfonated surface than on the unmodified one. This study was assisted with the atomic force microscopy. On the unmodified surface, BSA, adsorbed from sufficiently concentrated solutions, formed a monolayer, with occasional intrusions of multilayered patches. Conversely, the arrangement of BSA on the sulfonated surface was chaotic; the height of individual molecules was lower than on the unmodified polystyrene. Importantly, the adhesion study of LNCaP and DU145 cells indicated that both surfaces, subjected to the prior BSA adsorption, did not completely loose their cell-adhesive properties. However, the level of adhesion and the pattern of F-actin organization in adhering cells have shown that cells interacted with unmodified and sulfonated surfaces differently, depending on the arrangement of adsorbed albumin. These results suggest the presence of some bare substratum area accessible for cells after the albumin adsorption to both types of investigated surfaces.     

Cytocompatible encapsulation of individual Chlorella cells within titanium dioxide shells by a designed catalytic peptide

The individual encapsulation of living cells has a great impact on the areas of single cell-based sensors and devices as well as fundamental studies in single cell-based biology. In this work, living Chlorella cells were encapsulated individually with abiological, functionalizable TiO(2), by a designed catalytic peptide that was inspired by biosilicification of diatoms in nature. The bioinspired cytocompatible reaction conditions allowed the encapsulated Chlorella cells to maintain their viability and original shapes. After formation of the TiO(2) shells, the shells were postfunctionalized by using catechol chemistry. Our work suggests a bioinspired approach to the interfacing of individual living cells with abiological materials in a controlled manner.     

Characterization of surface properties and cytocompatibility of ion-etched chitosan films

Surface modification of biomaterials has been highlighted by biomedical engineers as a facile method for improving cell-biomaterial interactions without the expense and time required to develop new materials. In the present study, we investigated the influence of ion-etching on the surface characteristics of chitosan films using XPS and ATR FT-IR. The physiological behavior of human dermal fibroblasts (hDFs) grown on such surfaces was studied by evaluating adhesive and proliferative properties, and by examining surface morphologies of hDFs using AFM. hDFs displayed different shapes depending on the ion-etching time. hDFs grown on chitosan films ion-etched for 5 min displayed better development of lamellipodia and filopodia around the hDF periphery than did cells grown on nonmodified chitosan film, whereas hDFs did not spread well on films ion-etched for 20 min. Films ion-etched for 5 min or less had higher NH(2) and COOH contents, leading to enhanced hDF adhesion and proliferation.     

Direct synthesis of cup-stacked carbon nanofiber microspheres by the catalytic pyrolysis of poly(ethylene glycol)

Uniformly sized microspheres tangled with cup-stacked carbon nanofibers (CSCNFs) were directly synthesized by the pyrolysis of poly(ethylene glycol) (PEG) with a nickel catalyst. A PEG/Ni membrane was prepared on a silicon wafer surface by heating it to 750 °C at a heating rate of 15 °C min(-1). The wafer was heated to a temperature of 400 °C and was held at that temperature for 1 h before raising the temperature to 750 °C for 10 min to form the CSCNF microspheres. The final CSCNF microspheres and the intermediates were evaluated using scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and Raman spectroscopy to elucidate the growth mechanism. Furthermore, the CSCNF microspheres were successfully dispersed and maintained their spherical shape in an aqueous solution containing 0.5% Nafion. The CSCNF microspheres have the potential to work as a sophisticated carrier with high adsorption and fast electron-transfer exchange properties based on the graphene edges of the nanofiber surface.