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Microfluidic Assay Development

The development of rapid and portable pathogen/toxin screening equipment could help control outbreaks as well as product recalls. A trend in food processing facilities is the incorporation of on-site testing facilities in order to decrease turnaround time. Portable biosensor testing would allow analysis directly onto the processing floor, kitchen, farm or fishing vessel.
The device will incorporate disposable polymer chips for low cost rapid analysis. The assay will be designed to incorporate sample preparation from an immunomagnetically separated sample, amplification (such as NASBA or PCR), and electrochemilumenesence (ECL) detection. This has previously demonstrated successfully with the on-chip mRNA isolation as well as electrochemical detection of Cryptosporidium parvum. In this part of my research program, we will work towards developing a portable biosensor that combines isolation, amplification, and detection of pathogens and toxins in a hand-held device. ECL is a very sensitive detection methods with a limit of detection in the attomole range.

 

 
 

Portable Biosensing

With increased importing and exporting of food products between nations, rapid on-site food analysis could result in detection of possible health risks. Determination of total nitrogen in milk using Kjeldahl analysis is time consuming and can be swayed by the addition of nitrogen rich adulterants such as melamine. This was observed when milk adulterated with melamine resulted in the hospitalization of thousands of children.
A portable and inexpensive chemosensor for the detection of protein in milk could decrease illness associated with melamine adulteration.

 
 

Online Biosensing

In a food processing environment, several analyses are often conducted on each sample in order to detect multiple organisms. For example, while the presence of Listeria monocytogenes in food samples is an obvious alarm, non-pathogenic species of Listeria serve as indicator organisms for L. monocytogenes growth conditions. Development of handheld biosensors can aid in streamlining these analyses by permitting rapid screening of multiple samples against a range of organisms.
In silica analysis of genetic sequences can identify highly selective probes and primer sets for nucleic acid analysis. However, existing software tools are not easily adaptable to customized analysis, as is required for identification of multianalyte probes and primers.
We will develop a readily adaptable probe /primer designing program to optimize PCR/NASBA primer sets for Listeria spp. while selecting internal probes for specific species. This is done through communication with the (NCBI) genome database using the BLAST tools. The resulting customizable modeling program will enable more efficient and simultaneous detection of many pathogens.
This project will design a Listeria multi analyte detection system. Once capture probes specific to Listeria monocytogenes and Listeria spp. are determined from the program, we will incorporate these capture probes onto patterned electrodes in microfluidic chips for multi-analyte analysis.

 

 

Reporter Molecule Strategies

The design and synthesis of new marker molecules can reduce the limit of detection and increase sensitivity for bioassays. These advances are diven by the discovery of new materials in nanotechnology. Below is an image of gold nanoparticles with a silica shell which was fabricated in our lab.

nanoparticles