Biomedical subjects

Sara A Brazill

Publications and source records attributed to Sara A Brazill.

3 recordsLinked to original sources

PubMed2003

Independently-addressable micron-sized biosensor elements.

With the continuing development of micro-total analysis systems and sensitive biosensing technologies, it is often desirable to immobilize biomolecules onto a surface in a small well-defined area. A novel method was developed to electrochemically attach DNA probes to micron-sized regions of a gold surface using biotin-LC-hydrazide (BH). Previously, we have found that the radical produced during the oxidation of BH will attach to a wide variety of electroactive surfaces. An array of micron-sized gold band electrodes (75 microm wide) was fabricated onto glass microscope slides and BH was deposited onto each electrode through the application of an oxidizing potential. Subsequent attachment of avidin to the biotinylated surface created the 'molecular sandwich' architecture necessary for further immobilization of biotinylated biomolecules to the surface. In this work, we utilized biotinylated DNA probes of varying sequence to illustrate the specificity of the attachment scheme. The immobilization of avidin, DNA probe, and hybridization of DNA target is visualized with fluorescence tags and the spatially selective attachment and hybridization of unique DNA sequences is demonstrated.

Avidin↗

PubMed2002

A single base extension technique for the analysis of known mutations utilizing capillary gel electrophoreisis with electrochemical detection.

A novel single nucleotide polymorphism (SNP) detection system is described in which the accuracy of DNA polymerase and advantages of electrochemical detection are demonstrated. A model SNP system is presented to illustrate the potential advantages in coupling the single base extension (SBE) technique to capillary gel electrophoresis (CGE) with electrochemical detection. An electrochemically labeled primer, with a ferrocene acetate covalently attached to its 5' end, is used in the extension reaction. When the Watson-Crick complementary ddNTP is added to the SBE reaction, the primer is extended by a single nucleotide. The reaction mixture is subsequently separated by CGE, and the ferrocene-tagged fragments are detected at the separation anode with sinusoidal voltammetry. This work demonstrates the first single base resolution separation of DNA coupled with electrochemical detection. The unextended primer (20-mer) and the 21-mer extension product are separated with a resolution of 0.8.

Base Pairing↗

PubMed2002

Microchip capillary electrophoresis coupled to sinusoidal voltammetry for the detection of native carbohydrates.

The development of a microchip electrophoresis system involving integrated frequency based electrochemical detection is described. The use of poly(dimethylsiloxane) (PDMS) as the channel substrate greatly simplifies the fabrication process while decreasing cost and time consumption. Characterization of this system is accomplished through the detection of native carbohydrates at planar copper electrodes. Various photolithographic techniques are explored in the optimization of electrode area. Separation efficiency of 1 x 10(5) theoretical plates per meter is demonstrated. Sinusoidal voltammetry utilizes information in the frequency domain to achieve sensitive detection through either of two approaches, maximization of signal or minimization of noise. Mass detection limits (S/N = 3) of less than 200 amol have been accomplished for glucose and sucrose. Sinusoidal voltammetry also facilitated the selective isolation of an analyte signal from a pair of chromatographically unresolved species through the use of phase discrimination.

Carbohydrates↗