Electrochemical detection of synthetic DNA and native 16S rRNA fragments on a microarray using a biotinylated intercalator as coupling site for an enzyme label.

The direct electrochemical detection of synthetic DNA and native 16S rRNA fragments isolated from Escherichia coli is described. Oligonucleotides are detected via selective post-labeling of double stranded DNA and DNA-RNA duplexes with a biotinylated intercalator that enables high-specific binding of a streptavidin/alkaline phosphatase conjugate. The alkaline phosphatase catalyzes formation of p-aminophenol that is subsequently oxidized at the underlying gold electrode and hence enables the detection of complementary hybridization of the DNA capture strands due to the enzymatic signal amplification.

A microelectrochemical sensing system for the determination of Epstein-Barr virus antibodies.

An electrochemical method for the detection of Epstein-Barr virus (EBV) infections is described. The method relies on an immunoassay with electrochemical read-outs based on recombinant antigens. The antigens are immobilised on an Au electrode surface and used to complementarily bind antibodies from serum samples found during different stages of infection with EBV.

Imaging biocatalytic activity of enzyme-polymer spots by means of combined scanning electrochemical microscopy/electrogenerated chemiluminescence.

The purpose of this study was to develop a scanning electrochemical microscopy (SECM) and scanning electrogenerated chemiluminescence (SECL) setup to visualize the localized enzymatic activity using glucose oxidase as a model. Combination of SECM and electrogenerated chemiluminescence (ECL) was made possible by integrating a photomultiplier tube (PMT) within a SECM setup which is mounted on top of an inverted microscope. An enzyme-polymer spot formed on a glass slide and placed on top of the entrance window of the PMT was used as a model sample to evaluate the potential of the combined SECM/ECL setup.

Local modulation of the redox state of p-nitrothiophenol self-assembled monolayers using the direct mode of scanning electrochemical microscopy.

Local reduction of the terminating nitro groups of a p-nitrothiophenol self-assembled monolayer (SAM) under formation of either hydroxylamine or amino groups is invoked using the direct mode of scanning electrochemical microscopy (SECM). By choosing the appropriate potential and a potential pulse sequence, the reduction of the SAM end groups to the desired oxidation state can be achieved, locally restricted to the area of the sample surface directly underneath the positioned SECM tip. Following the "writing" of redox microstructures within the SAM end groups, the local modification of the redox states is visualized ("reading") by using the feedback mode of SECM.

Optimization of an electrochemical DNA assay by using a 48-electrode array and redox amplification studies by means of scanning electrochemical microscopy.

Sensible DNA: An electrochemical DNA assay based on specific Salmonella spp. capture probes and enzyme labeling with alkaline phosphatase was optimized by using a 48-electrode microarray and scanning electrochemical microscopy (SECM). SECM was further used to evaluate potential amplification strategies due to redox cycling.

Scanning electrochemical microscopy (SECM) as a tool in biosensor research.

Scanning electrochemical microscopy (SECM) is discussed as a versatile tool to provide localized (electro)chemical information in the context of biosensor research. Advantages of localized electrochemical measurements will be discussed and a brief introduction to SECM and its operation modes will be given. Experimental challenges of the different detection modes of SECM and its applicability for different fields in biosensor research are discussed.

Analysis in ultrasmall volumes: microdispensing of picoliter droplets and analysis without protection from evaporation.

A new approach is reported for analysis of ultrasmall volumes. It takes advantage of the versatile positioning of a dispenser to shoot approximately 150-pL droplets of liquid onto a specific location of a substrate where analysis is performed rapidly, in a fraction of the time that it takes for the droplet to evaporate. In this report, the site where the liquid is dispensed carries out fast-scan cyclic voltammetry (FSCV), although the detection method does not need to be restricted to electrochemistry.