Biomedical subjects

Scott D Soelberg

Publications and source records attributed to Scott D Soelberg.

3 recordsLinked to original sources

PubMed2007

Portable 24-analyte surface plasmon resonance instruments for rapid, versatile biodetection.

Field use of surface plasmon resonance (SPR) biosensors for environmental and defense applications such as detection and identification of biological warfare agents has been hampered by lack of rugged, portable, high-performance instrumentation. To meet this need, we have developed compact multi-analyte SPR instruments based on Texas Instruments' Spreeta sensing chips. The instruments weigh 3 kg and are built into clamshell enclosures measuring 28 cm x 22 cm x 13 cm. Functions are divided between an electronics unit in the base of the box and a fluidics assembly in the lid. Automated valves and pumps implement an injection loop flow system that allows sensors to be exposed to sample, rinsed, and treated with additional reagents (such as secondary antibodies) under computer control. Injected samples flow over the surfaces of eight sensor chips fastened into a temperature-controlled silicone flowcell. Each chip has 3 sensing regions, for a total detection of 24 areas that can be simultaneously monitored by SPR. Coating these areas with appropriate antibodies or other receptors allows a sample to be screened for up to 24 different substances simultaneously. The instruments report refractive index (RI) values every second, with a typical noise level of 1-3 x 10(-6) RI units. The design of the device is described, and performance is illustrated with detection of six distinct analytes ranging from small molecules to whole microbes during the course of a single experiment.

Biological Warfare↗

PubMed2005

A portable surface plasmon resonance sensor system for real-time monitoring of small to large analytes.

Many environmental applications exist for biosensors capable of providing real-time analyses. One pressing current need is monitoring for agents of chemical- and bio-terrorism. These applications require systems that can rapidly detect small organics including nerve agents, toxic proteins, viruses, spores and whole microbes. A second area of application is monitoring for environmental pollutants. Processing of grab samples through chemical laboratories requires significant time delays in the analyses, preventing the rapid mapping and cleanup of chemical spills. The current state of development of miniaturized, integrated surface plasmon resonance (SPR) sensor elements has allowed for the development of inexpensive, portable biosensor systems capable of the simultaneous analysis of multiple analytes. Most of the detection protocols make use of antibodies immobilized on the sensor surface. The Spreeta 2000 SPR biosensor elements manufactured by Texas Instruments provide three channels for each sensor element in the system. A temperature-controlled two-element system that monitors for six analytes is currently in use, and development of an eight element sensor system capable of monitoring up to 24 different analytes will be completed in the near future. Protein toxins can be directly detected and quantified in the low picomolar range. Elimination of false positives and increased sensitivity is provided by secondary antibodies with specificity for different target epitopes, and by sensor element redundancy. Inclusion of more than a single amplification step can push the sensitivity of toxic protein detection to femtomolar levels. The same types of direct detection and amplification protocols are used to monitor for viruses and whole bacteria or spores. Special protocols are required for the detection of small molecules. Either a competition type assay where the presence of analyte inhibits the binding of antibodies to surface-immobilized analyte, or a displacement assay, where antibodies bound to analyte on the sensor surface are displaced by free analyte, can be used. The small molecule detection assays vary in sensitivity from the low micromolar range to the high picomolar.

Biosensing Techniques↗

PubMed2002

Detection of Staphylococcus aureus enterotoxin B at femtomolar levels with a miniature integrated two-channel surface plasmon resonance (SPR) sensor.

Surface plasmon resonance (SPR) biosensors offer the capability for continuous real-time monitoring. The commercial instruments available have been large in size, expensive, and not amenable to field applications. We report here an SPR sensor system based on a prototype two-channel system similar to the single channel Spreeta devices. This system is an ideal candidate for field use. The two-channel design provides a reference channel to compensate for bulk refractive index (RI), non-specific binding and temperature variations. The SPR software includes a calibration function that normalizes the response from both channels, thus enabling accurate referencing. In addition, a temperature-controlled enclosure utilizing a thermo-electric module based on the Peltier effect provides the temperature stability necessary for accurate measurements of RI. The complete SPR sensor system can be powered by a 12V battery. Pre-functionalized, disposable, gold-coated thin glass slides provide easily renewable sensor elements for the system. Staphylococcus aureus enterotoxin B (SEB), a small protein toxin was directly detectable at sub-nanomolar levels and with amplification at femtomolar levels. A regeneration procedure for the sensor surface allowed for over 60 direct detection cycles in a 1-month period.

Animals↗