Biomedical subjects

Soohyoun Ahn

Publications and source records attributed to Soohyoun Ahn.

4 recordsLinked to original sources

PubMed2006

Fiber-optic microsphere-based arrays for multiplexed biological warfare agent detection.

We report a multiplexed high-density DNA array capable of rapid, sensitive, and reliable identification of potential biological warfare agents. An optical fiber bundle containing 6000 individual 3.1-mum-diameter fibers was chemically etched to yield microwells and used as the substrate for the array. Eighteen different 50-mer single-stranded DNA probes were covalently attached to 3.1-mum microspheres. Probe sequences were designed for Bacillus anthracis, Yersinia pestis, Francisella tularensis, Brucella melitensis, Clostridium botulinum, Vaccinia virus, and one biological warfare agent (BWA) simulant, Bacillus thuringiensis kurstaki. The microspheres were distributed into the microwells to form a randomized multiplexed high-density DNA array. A detection limit of 10 fM in a 50-microL sample volume was achieved within 30 min of hybridization for B. anthracis, Y. pestis, Vaccinia virus, and B. thuringiensis kurstaki. We used both specific responses of probes upon hybridization to complementary targets as well as response patterns of the multiplexed array to identify BWAs with high accuracy. We demonstrated the application of this multiplexed high-density DNA array for parallel identification of target BWAs in spiked sewage samples after PCR amplification. The array's miniaturized feature size, fabrication flexibility, reusability, and high reproducibility may enable this array platform to be integrated into a highly sensitive, specific, and reliable portable instrument for in situ BWA detection.

Biological Warfare↗

PubMed2006

Fiber-optic microarray for simultaneous detection of multiple harmful algal bloom species.

Harmful algal blooms (HABs) are a serious threat to coastal resources, causing a variety of impacts on public health, regional economies, and ecosystems. Plankton analysis is a valuable component of many HAB monitoring and research programs, but the diversity of plankton poses a problem in discriminating toxic from nontoxic species using conventional detection methods. Here we describe a sensitive and specific sandwich hybridization assay that combines fiber-optic microarrays with oligonucleotide probes to detect and enumerate the HAB species Alexandrium fundyense, Alexandrium ostenfeldii, and Pseudo-nitzschia australis. Microarrays were prepared by loading oligonucleotide probe-coupled microspheres (diameter, 3 mum) onto the distal ends of chemically etched imaging fiber bundles. Hybridization of target rRNA from HAB cells to immobilized probes on the microspheres was visualized using Cy3-labeled secondary probes in a sandwich-type assay format. We applied these microarrays to the detection and enumeration of HAB cells in both cultured and field samples. Our study demonstrated a detection limit of approximately 5 cells for all three target organisms within 45 min, without a separate amplification step, in both sample types. We also developed a multiplexed microarray to detect the three HAB species simultaneously, which successfully detected the target organisms, alone and in combination, without cross-reactivity. Our study suggests that fiber-optic microarrays can be used for rapid and sensitive detection and potential enumeration of HAB species in the environment.

Base Sequence↗

PubMed2005

Detection of Salmonella spp. using microsphere-based, fiber-optic DNA microarrays.

Salmonella spp. are one of the most problematic food pathogens in public health, as they are responsible for food poisoning associated with contamination of meat, poultry, and eggs. Thus, rapid and sensitive detection of Salmonella spp. is required to ensure food safety. In this study, a fiber-optic DNA microarray using microsphere-immobilized oligonucleotide probes specific for the Salmonella invA and spvB genes was developed for detection of Salmonella spp. Microarrays were prepared by randomly distributing DNA probe-functionalized microspheres (3.1-microm diameter) into microwells created by etching optical fiber bundles. Hybridization of the probe-functionalized microspheres to target DNA from Salmonella was performed and visualized using Cy3-labeled secondary probes in a sandwich-type assay format. In this study, 10(3)-10(4) cfu/mL of the target organism could be detected after 1-h hybridization without any additional amplification. The DNA microarray showed no cross-reactivity with other common food pathogens, including E. coli and Y. enterocolitica, and could even detect Salmonella spp. from cocktails of bacterial strains with only moderate loss of sensitivity due to nonspecific binding. This work suggests that fiber-optic DNA microarrays can be used for rapid and sensitive detection of Salmonella spp. Since fiber-optic microarrays can be prepared with different probes, this approach could also enable the simultaneous detection of multiple food pathogens.

Bacterial Proteins↗

PubMed2005

Detecting biological warfare agents.

We developed a fiber-optic, microsphere-based, high-density array composed of 18 species-specific probe microsensors to identify biological warfare agents. We simultaneously identified multiple biological warfare agents in environmental samples by looking at specific probe responses after hybridization and response patterns of the multiplexed array.

Bacteria↗