Annual Report - Center for Food Safety Engineering - Purdue ...

Stanciu and AndreescuPortable biosensor for rapid and ultra-sensitive identificationof organophoshorous foodborne contaminantsInvestigators: Lia Stanciu (Department of Materials Engineering), Silvana Andreescu (Clarkson University)Project RationaleThe overall goal of this project was to advance the fi eld ofpesticide detection in food by developing ultra-sensitivebiosensors based on immobilized acetylcholinesterase (AChE).Over the past decades, AChE biosensors have emerged as apromising technique for food quality control. The developmentof these biosensors could complement or replace classicalanalytical methods by simplifying or eliminating samplepreparation and making identifi cation of chemical foodbornecontaminants easier and faster, with signifi cant decreases inanalysis time and cost.Project Objectives• Establish the optimum parameters for the immobilizationof AChE and the need and feasibility of using anoxidation strategy for phosphorothionates.• Fabricate and characterize the AChE biosensorby immobilizing the enzyme onto the surfaceof single-use screen-printing electrodes (SPE).Study enzyme stability and leaching.• Detect pesticides. Obtain calibration plots of theinhibitory degree upon application of variousconcentrations of pesticides. Determine thedetection limit (DL), response time (RT), and linearconcentration range (LCR) for selected pesticides.• Assemble and test the biosensor prototype for the analysisof pesticides in food samples. Evaluate the matrix effectsand establish whether an extraction step is needed.biosensors with enhanced characteristics. We are the fi rstresearchers to use this direct binding of enzymes onto Ni-NPsfor this purpose. This accomplishment is important becausesite-specifi c orientation of enzymes onto electrode surfaceshas numerous advantages over classical procedures. It ishighly sensitive, avoids conformational changes, decreasessensor costs (due to a lower enzyme requirement), and entailsa simple single fabrication step. This method has the potentialto become a robust, commercially viable system.Alternatively, the procedure combining sol-gel technology withscreen-printing protocols is also potentially useful for biosensorfabrication. Moreover, the sol-gel method is a versatile andeffi cient technique for conserving enzyme activity in organicsolvents. We expect that this matrix will enable functionality ofthe enzyme in the presence of organic solvents, if this mediumis necessary to extract the pesticides from the food matrix.Project HighlightsWe have made signifi cant progress toward establishingthe optimum parameters for enzyme immobilization usingtwo matrices (sol-gel and Ni-nanoparticles)) that enablepreservation of enzymatic activity. The procedure involvingattachment via affi nity binding to Ni-nanoparticles is new andhighly innovative and can be used to fabricate a new class of16Center for Food Safety Engineering“The development of these biosensors could complement or replace classicalanalytical methods by simplifying or eliminating sample preparation and makingidentifi cation of chemical foodborne contaminants easier and faster.”