Time filter

Source Type

München, Germany

Zimdars A.,Friz Biochem | Gebala M.,Ruhr University Bochum | Gebala M.,Stanford University | Hartwich G.,Friz Biochem | And 2 more authors.
Talanta | Year: 2015

Abstract 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. The hybridization assay was performed on microarrays consisting of 32 individually addressable gold microelectrodes. Synthetic DNA strands with sequences representing six different pathogens which are important for the diagnosis of urinary tract infections could be detected at concentrations of 60 nM. Native 16S rRNA isolated from the different pathogens could be detected at a concentration of 30 fM. Optimization of the sensing surface is described and influences on the assay performance are discussed. © 2015 Elsevier B.V.

Frey A.,Siemens AG | Kruppa P.,TU Munich | Kuehne I.,Siemens AG | Schienle M.,Siemens AG | And 3 more authors.
ESSCIRC 2010 - 36th European Solid State Circuits Conference | Year: 2010

A rail-to-rail potentiostat circuit suitable for CMOS based electronic bio sensors is presented. The design approach enables robust operation far a large range of electrochemical conditions. Measurement results prove proper operation of the potentiostatic control circuitry. ©2010 IEEE.

Bandilla M.,Friz Biochem | Zimdars A.,Friz Biochem | Neugebauer S.,Ruhr University Bochum | Motz M.,Mikrogen GmbH | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2010

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. Thiol chemistry under formation of self-assembled monolayers functions as a means to immobilise the antigens at the Au electrodes. A reporter system consisting of a secondary antibody labelled with alkaline phosphatase is used for electrochemical detection. The feasibility of the assay design is demonstrated and the assay performance is tested against the current gold standard in EBV detection. Close correlation is obtained for the results found for the developed electrochemical immunoassay and a standard line assay. Moreover, the electrochemical immunoassay is combined with a nanoporous electrode system allowing signal amplification by means of redox recycling. An amplification factor of 24 could be achieved. © Springer-Verlag 2010.

Discover hidden collaborations