Biomedical subjects

Chris Rowe Taitt

Publications and source records attributed to Chris Rowe Taitt.

8 recordsLinked to original sources

PubMed2006

Multiplexed measurement of serum antibodies using an array biosensor.

The array biosensor provides the capability for simultaneously measuring titers of antibody against multiple antigens. Human antibodies against four different targets, tetanus toxin, diphtheria toxin, staphylococcal enterotoxin B (SEB) and hepatitis B, were measured simultaneously in sera from eight different donors in a single assay and titers were determined. The assays could measure amounts of bound antibody as low as approximately 100 fg. Each individual serum exhibited a different pattern of reactivity against the four target antigens. Applications of this biosensor capability include monitoring for exposure to pathogens and for efficacy of vaccination.

Animals↗

PubMed2005

Antimicrobial peptides for detection of bacteria in biosensor assays.

Bacteria, plants, and higher and lower animals have evolved an innate immune system as a first line of defense against microbial invasion. Some of these organisms produce antimicrobial peptides (AMPs) as a part of this chemical immune system. AMPs exert their antimicrobial activity by binding to components of the microbe's surface and disrupting the membrane. The overall goal of this study was to apply the AMP magainin I as a recognition element for Escherichia coli O157:H7 and Salmonella typhimurium detection on an array-based biosensor. We immobilized magainin I on silanized glass slides using biotin-avidin chemistry, as well as through direct covalent attachment. Cy5-labeled, heat-killed cells were used to demonstrate that the immobilized magainin I can bind Salmonella with detection limits similar to analogous antibody-based assays. Detection limits for E. coli were higher than in analogous antibody-based assays, but it is expected that other AMPs may possess higher affinities for this target. The results showed that both specific and nonspecific binding strongly depend on the method used for peptide immobilization. Direct attachment of magainin to the substrate surface not only decreased nonspecific cell binding but also resulted in improved detection limits for both Salmonella and E. coli.

Anti-Infective Agents↗

PubMed2004

Evanescent wave fluorescence biosensors.

Since discovery and first use in the mid-1970s, evanescent wave fluorescence biosensors have developed into a diverse range of instruments, each designed to meet a particular detection need. In this review, we provide a brief synopsis of what evanescent wave fluorescence biosensors are, how they work, and how they are used. In addition, we have summarized the important patents that have impacted the evolution from laboratory curiosities to fully automated commercial products. Finally, we address the critical issues that evanescent wave fluorescence biosensors will face in the coming years.

Biosensing Techniques↗

PubMed2004

Fragmentation of biotinylated cyclic peptides.

Electrospray ionization coupled with tandem mass spectrometry (MS/MS) was used to determine the preferred binding site(s) of biotin NHS ester with a series of cyclic peptides with antibiotic properties. The peptides investigated are polymyxins, cyclic peptides produced by Bacillus polymyxa. In spite of the 1:1 stoichiometry used in the labeling reaction, multiple biotin molecules were incorporated into intact polymyxin peptides. Given the amine specificity of the activated biotin and the large number of amino acids with primary amines in the polymyxins, it was not clear by inspection which binding sites were more reactive than others. MS/MS was used to characterize the structure of the biotinylated peptides. MS/MS spectra of cyclic peptides often lead to ambiguous structure determinations due to the potential for multiple ring openings which result in the generation of multiple ion series. The MS/MS spectra of polymyxin peptides are especially difficult to characterize due to the lack of variety in their amino acids; however, the added complexity of the biotin aided the elucidation of the fragmentation pathways. MS/MS spectra of the species with biotin additions were used to rationalize the preferential binding sites of these molecules.

Anti-Bacterial Agents↗

PubMed2004

Detection of Salmonella enterica serovar typhimurium by using a rapid, array-based immunosensor.

The multianalyte array biosensor (MAAB) is a rapid analysis instrument capable of detecting multiple analytes simultaneously. Rapid (15-min), single-analyte sandwich immunoassays were developed for the detection of Salmonella enterica serovar Typhimurium, with a detection limit of 8 x 10(4) CFU/ml; the limit of detection was improved 10-fold by lengthening the assay protocol to 1 h. S. enterica serovar Typhimurium was also detected in the following spiked foodstuffs, with minimal sample preparation: sausage, cantaloupe, whole liquid egg, alfalfa sprouts, and chicken carcass rinse. Cross-reactivity tests were performed with Escherichia coli and Campylobacter jejuni. To determine whether the MAAB has potential as a screening tool for the diagnosis of asymptomatic Salmonella infection of poultry, chicken excretal samples from a private, noncommercial farm and from university poultry facilities were tested. While the private farm excreta gave rise to signals significantly above the buffer blanks, none of the university samples tested positive for S. enterica serovar Typhimurium without spiking; dose-response curves of spiked excretal samples from university-raised poultry gave limits of detection of 8 x 10(3) CFU/g.

Animals↗

PubMed2003

Array biosensor for detection of toxins.

The array biosensor is capable of detecting multiple targets rapidly and simultaneously on the surface of a single waveguide. Sandwich and competitive fluoroimmunoassays have been developed to detect high and low molecular weight toxins, respectively, in complex samples. Recognition molecules (usually antibodies) were first immobilized in specific locations on the waveguide and the resultant patterned array was used to interrogate up to 12 different samples for the presence of multiple different analytes. Upon binding of a fluorescent analyte or fluorescent immunocomplex, the pattern of fluorescent spots was detected using a CCD camera. Automated image analysis was used to determine a mean fluorescence value for each assay spot and to subtract the local background signal. The location of the spot and its mean fluorescence value were used to determine the toxin identity and concentration. Toxins were measured in clinical fluids, environmental samples and foods, with minimal sample preparation. Results are shown for rapid analyses of staphylococcal enterotoxin B, ricin, cholera toxin, botulinum toxoids, trinitrotoluene, and the mycotoxin fumonisin. Toxins were detected at levels as low as 0.5 ng mL(-1).

Biosensing Techniques↗

PubMed2002

Nine-analyte detection using an array-based biosensor.

A fluorescence-based multianalyte immunosensor has been developed for simultaneous analysis of multiple samples. While the standard 6 x 6 format of the array sensor has been used to analyze six samples for six different analytes, this same format has the potential to allow a single sample to be tested for 36 different agents. The method described herein demonstrates proof of principle that the number of analytes detectable using a single array can be increased simply by using complementary mixtures of capture and tracer antibodies. Mixtures were optimized to allow detection of closely related analytes without significant cross-reactivity. Following this facile modification of patterning and assay procedures, the following nine targets could be detected in a single 3 x 3 array: Staphylococcal enterotoxin B, ricin, cholera toxin, Bacillus anthracis Sterne, Bacillus globigii, Francisella tularensis LVS, Yersiniapestis F1 antigen, MS2 coliphage, and Salmonella typhimurium. This work maximizes the efficiency and utility of the described array technology, increasing only reagent usage and cost; production and fabrication costs are not affected.

Antigens↗

PubMedDate not supplied

Applications of array biosensor for detection of food allergens.

Although food is a necessity, compounds within food products can be dangerous and life-threatening for people with food allergies. These allergy-causing compounds, such as proteins from eggs and milk, must be identified on the labels of commercial products. Unintentional contamination of food with these compounds occurs as a result of storage, manufacturing procedures, or cleaning procedures. A sensitive, specific, and rapid method to identify foods containing allergens is required by the food industry. The array biosensor, a rapid detection system, may provide a solution to this need. The array biosensor performs fluorescent immunoassays on the surface of a planar waveguide by first running samples, then fluorescently labeled antibodies, over a surface patterned with capture antibodies. An optical image is captured by a charged-coupled device camera and converted into fluorescence values. Signal intensity and spot location provide information on the compound and its concentration. The array biosensor has been successfully demonstrated for toxin, bacteria, and virus detection at low levels in under 20 min in food, clinical samples, and environmental matrixes. An assay for detection of ovalbumin as an indicator of egg contamination has been developed with limits of detection of 25 pg/mL in buffer and 1.3 ng/mL (13 ng/g) in non-egg pasta extract (buffer:pasta 10:1, v/w).

Allergens↗