Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Rosa L. Cromartie - Florida International University
Co-Author(s): Ashley Wardlow and Bruce McCord, Florida International University, Miami, FL George Duncan, Broward Sheriff's Office, Ft.Lauderdale, FL
There have been new developments in the field of forensic serology, e.g. genomics and proteomics, which involve lengthy laboratory testing and are not applicable to direct measurements at a crime scene. Even though field-able tests are simple, fast and presumptive, these analyses generally involve multiple procedures for each body fluid, e.g. blood, semen, vaginal fluids, and urine. We are examining a new, more cost effective method such as multiplexed presumptive body fluid screening procedure using paper microfluidics. Paper microfluidic devices (μPADs) allow for fluid handling and quantitative analysis in medical and scientific fields. μPADs allows micro-scale operations to be performed outside and within a laboratory. Using sheets of chromatographic paper and thermal wax to create hydrophobic which direct a liquid sample to multiple test wells each with a different sensor. Paper microfluidics devices have the potential to revolutionize forensic serology by permitting the simultaneous analysis of multiple sources of body fluids from a variety of substrates using multiplexed colorimetric detection. Designed like a tree, each terminus contains a colorimetric reagent capable of identifying a specific bodily fluid. A single sample is placed at the base of the device and flows into several branches with different reagents. Currently, four different fluids can be simultaneously detected on a single device. In this project a variety of colorimetric sensing systems have been developed and modified for the presumptive determination of blood, urine, saliva and semen. Reagents for detecting blood were prepared using sodium perborate as a longer lasting oxidizing agent for the phenolphthalein based Kastle-Meyer test. This compound becomes oxidized when sodium perborate comes in contact with water generating hydrogen peroxide. A colorimetric change is produced in a minimum of 10 seconds. To detect urine, a second test site utilizes the hydrolysis of urea via urease. The ammonia that is released interacts with the Nessler’s reagent (mercuric iodide) and produces color change in under a minute. The reagents used for saliva detection utilize the amylase based hydrolysis of the alpha-1,4 glyosidic linkages in starch/iodine resulting in the loss of the initial colored complex. Reagents used for semen involve the reaction of sodium alpha-naphthyl phosphate with acid phosphatase. Upon analysis, the paper microfluidic chip permits the determination of sub-microliter volumes of samples. The design of this system has been tested and validated, including sensitivity, specificity and long term stability. Overall this paper microfluidic presumptive testing method can serve as a cost effective and field-able analytical method for screening unknown fluids found at crime scenes.
Funder Acknowledgement(s): NSF-FGLSAMP Bridge to the Doctorate
Faculty Advisor: Bruce McCord, email@example.com
Role: I performed the project entirely.