Waveguide Fabrication In UV-Photocurable Sol–Gel Materials: Influence Of The Photoinitiating System

In this paper we identify and explain the different chemical interactions involved between a sol–gel matrix and photoinitiators used in the fabrication of optical waveguides. A well-established sol–gel matrix composed of 3-methacryloxypropyltrimethoxysilane, zirconium n-propoxide and methacrylic acid was developed, and two different photoinitiators (Irgacure® 819 and 1800) were added to the host matrix. Optical microscopy was used to characterise the structure of the waveguides as a function of the photoinitiator nature and concentration, and aging of the hybrid sol–gel material. It is clearly demonstrated that the width of the waveguides is strongly influenced by the sol aging. Furthermore, it is shown that degradation of photoinitiators occurs during the sol–gel process. Oxidation of the phosphonyl groups by the zirconium complex accounts for this results

Improving the sensitivity of immunoassays with PEG-COOH-like film prepared by plasma-based technique

Herein we report on a preparation and performance of stable, hydrophilic and biocompatible polymeric material suitable for functionalization of disposable substrates used in biosensors. This new material features -COOH surface groups cross-linked with ethylene glycol molecules and was prepared in situ on disposable, plastic substrate by high-throughput and environmentally friendly technique called plasma-enhanced chemical vapor deposition (PECVD). The film is grafted to the plasma activated plastic by sequential deposition of tetraethylorthosilicate, forming a bonding layer, and mixed vapors of acrylic acid and diethyleneglycol dimethylether (AA/PEG) that provide the desired functional groups forming a sensing, contact layer. A superior performance of the AA/PEG coating as suitable material for substrates in biomedical devices was demonstrated in a model fluorescence linked immunosorbent assay. The results were compared with other commonly used surface materials prepared by wet chemistry methods. The unique characteristic of the AA/PEG film is that the immunoassay can be executed without the need for a blocking step, typically using albumins, without negative consequences on the bioassay results. In fact, the superior quality of the materials modified with AA/PEG film was highlighted by improving the sensitivity of an immunoassay by two orders of magnitude when compared with substrates prepared by standard surface chemistry methods. Copyright © 2011 Wiley Periodicals, Inc

TIRF microscopy as a screening method for non-specific binding on surfaces

We report a method for studying nanoparticle-biosensor surface interactions based on total internal reflection fluorescence (TIRF) microscopy. We demonstrate that this simple technique allows for high throughput screening of non-specific adsorption (NSA) of nanoparticles on surfaces of different chemical composition. Binding events between fluorescent nanoparticles and functionalized Zeonor® surfaces are observed in real-time, giving a measure of the attractive or repulsive properties of the surface and the kinetics of the interaction. Three types of coatings have been studied: one containing a polymerized aminosilane network with terminal -NH2 groups, a second film with a high density of -COOH surface groups and the third with sterically restraining branched poly(ethylene)glycol (PEG) functionality. TIRF microscopy revealed that the NSA of nanoparticles with negative surface charge on such modified coatings decreased in the following order -NH2>-branched PEG>-COOH. The surface specificity of the technique also allows discrimination of the degree of NSA of the same surface at different pH. © 2010 Elsevier Inc

Multisubstrate-compatible ELISA procedures for rapid and high-sensitivity immunoassays

10.1038/nprot.2011.304Nature Protocols64439-44

Evaluation of apparent non-specific protein loss due to adsorption on sample tube surfaces and/or altered immunogenicity

10.1039/c0an00689kAnalyst13671406-1411ANAL

Waveguide Fabrication In UV-Photocurable Sol–Gel Materials: Influence Of The Photoinitiating System

In this paper we identify and explain the different chemical interactions involved between a sol–gel matrix and photoinitiators used in the fabrication of optical waveguides. A well-established sol–gel matrix composed of 3-methacryloxypropyltrimethoxysilane, zirconium n-propoxide and methacrylic acid was developed, and two different photoinitiators (Irgacure® 819 and 1800) were added to the host matrix. Optical microscopy was used to characterise the structure of the waveguides as a function of the photoinitiator nature and concentration, and aging of the hybrid sol–gel material. It is clearly demonstrated that the width of the waveguides is strongly influenced by the sol aging. Furthermore, it is shown that degradation of photoinitiators occurs during the sol–gel process. Oxidation of the phosphonyl groups by the zirconium complex accounts for this results

Development of a high sensitivity rapid sandwich ELISA procedure and its comparison with the conventional approach

10.1021/ac101339qAnalytical Chemistry82167049-7052ANCH