Purdue MSE researchers create Electrochemical Biosensors with Polyelectrolyte Microspheres

The ongoing trend of inter-disciplinary work here in the Materials Department continues with fourth year Ph.D. candidate Alexandra Snyder. After obtaining her degree from the Chemistry Department at Penn State University with a specialization in Polymer Science, Alex found an ideal fit with Professor Lia Stanciu and her research group in the area of biosensors. Taking advantage of support from the United States Department of Education’s GAANN Fellowship she has had opportunities to collaborate with research groups both inside the department via Professor Martinez and Professor Moon and also with those in Mechanical (Professor Nauman) and Biomedical Engineering here at Purdue.

The ongoing trend of inter-disciplinary work here in the Materials Department continues with fourth year Ph.D. candidate Alexandra Snyder. After obtaining her degree from the Chemistry Department at Penn State University with a specialization in Polymer Science, Alex found an ideal fit with Professor Lia Stanciu and her research group in the area of biosensors. Taking advantage of support from the United States Department of Education’s GAANN Fellowship she has had opportunities to collaborate with research groups both inside the department via Professor Martinez and Professor Moon and also with those in Mechanical (Professor Nauman) and Biomedical Engineering here at Purdue.


Biosensors contain three main components; an electrode, transducer and lastly a bio-active material. The biosensors of interest here use enzymes that change their catalytic activity (current carrying capability) when they come into contact with the sensing agent. This loss of activity is noticed externally by the researchers as a change in electrical current which can be easily correlated to a concentration of the target chemical.


A specialized fabrication technique is used by the Stanciu Group to form a polyelectrolyte coating on the surface of polystyrene sulfonate spheres. This layer by layer deposition (LbL) method allows them to control the surface charge and chemistry which in turn allows for greater control over which sensing enzymes can be attached. Alex’s research focus was on using the enzymes acetylcholinesterase(AChE) and horseradish peroxidase(HRP) to detect organophosphates such as the pesticide paraoxon and hydrogen peroxide, respectively. Using this LbL technique to bind
these enzymes to the surface of these spheres has allowed detection limits of approximately one part per ten-million for the organophosphate and one part per million for hydrogen peroxide. These detection ranges are optimal for industrial waste applications due to the toxicity of these chemicals. This work into purely organic biosensors has been recently published in the Journal of The Electrochemical Society and can be found here. Continuing work to improve the long term stability of these systems has drawn Alex and her group to investigate a hybrid organic-inorganic biosensor, this work is to be presented at the Materials Research Society’s Spring meeting in March. These hybrid biosensors address a pressing issue in environmental safety concerns by detecting trace amounts of Bisphenol-A (BPA) which has been of recent concern for its presence in consumer plastics.