Development of a Bioactive Paper Sensor for Detection of Neurotoxins Using Piezoelectric Inkjet Printing of Sol−Gel-Derived Bioinks

Abstract

There is an increasing interest in new strategies to rapidly detect analytes of clinical and environmental interest without the need for sophisticated instrumentation. As an example, the detection of acetylcholinesterase (AChE) inhibitors such as neurotoxins and organophosphates has implications for neuroscience, drug assessment, pharmaceutical development, and environmental monitoring. Functionalization of surfaces with multiple reagents, including enzymes and chromogenic reagents, is a critical component for the effective development of "dipstick" or lateral flow biosensors. Herein, we describe a novel paper-based solid-phase biosensor that utilizes piezoelectric inkjet printing of biocompatible, enzyme-doped, sol-gel-based inks to create colorimetric sensor strips. For this purpose, polyvinylamine (PVAm, which captures anionic agents) was first printed and then AChE was overprinted by sandwiching the enzyme within two layers of biocompatible sol-gel-derived silica on paper. AChE inhibitors, including paraoxon and aflatoxin B1, were detected successfully using this sensor by measuring the residual activity of AChE on paper, using Ellman's colorimetric assay, with capture of the 5-thio-2-nitrobenzoate (TNB(-)) product on the PVAm layer. The assay provided good detection limits (paraoxon, approximately 100 nM; aflatoxin B1, approximately 30 nM) and rapid response times (<5 min). Detection could be achieved either by eye or using a digital camera and image analysis software, avoiding the need for expensive and sophisticated instrumentation. We demonstrate that the bioactive paper strip can be used either as a dipstick or a lateral flow-based biosensor. The use of sol-gel-based entrapment produced a sensor that retained enzyme activity and gave reproducible results after storage at 4 degrees C for at least 60 days, making the system suitable for storage and use in the field.

Surface Functionalized Nanofibrillar Cellulose (NFC) Film as a Platform for Immunoassays and Diagnostics

“…The use of inkjet printing in biosensors and immunoassays supported on paper and other substrates has been widely reported [1,8,17,24]. The main advantages of the inkjet printing technique include small demand of printing liquids (expensive purified antibodies and enzymes can be used) [7], and the lack of physical contact with the object, which reduces the risk for surface contamination.…”

Practice-based Perspective on Technology Acceptance: Analyzing Bioactive Point of Care Testing

“…A growing number of studies indicate that biotechnology, in the form of biosensors and point of care tests for instance, opens up new opportunities for creating added value and for developing cost-effective products for health care (Olenic, et al, 2009;Gustafsson, et al, 2009;Hossain, et al, 2009). There is a need for new innovations in the health care market in developed and developing countries due to several reasons; the high standard of living in developed countries is creating more demand in the health care market, while the costs of public health care are expected to diminish.…”

A perspective on paper-based microfluidics: Current status and future trends

“…One proposal is combining assay reagents with sol-gel materials to immobilize reagents on paper. [64][65][66] In this way, Hossain et al developed a paper-based sensor which can detect organophosphate pesticides of nanomolar quantities in milk or lettuce by color changing. 65 Another proposal is using gold nanoparticle (AuNP) based colorimetric detection which can dramatically improve both the sensitivity and the specificity of detection.…”