August 7, 2009: Researchers at McMaster University in Ontario, Canada, have developed a method for printing a toxin-detecting biosensor on paper using bioactive inks.

The process, developed by researchers led by McMaster’s John Brennan and the Sentinel Bioactive Paper Network, a consortium of Canadian universities and industry, involves formulating an ink similar to that in computer print cartridges but with additives to make the ink biocompatible. First an ink of biocompatible silica nanoparticles and then a second ink with an enzyme are deposited on paper (they used a FujiFilm Dimatix materials printer), together forming a thin film. When exposed to a toxin, molecules in the ink change color depending on the concentration — not unlike how a home pregnancy kit works. They found they could detect two test neurotoxins both visually (naked eye) and with a digital camera/software; the sensors retained full activity after two months in storage at 4°C.

The process is said to be simple and cost-effective, two keys to achieving bioactive paper for fast, portable, disposable, and inexpensive sensor strips, used for monitoring environmental and food-based toxins and in remote underdeveloped regions needing simple biological tests for first-stage disease detection. Other applications for bioactive paper include clinical applications in neuroscience, drug assessment, and pharmaceutical development.

The research, published in the July 1 issue of Analytical Chemistry, “represents the first report published on the utilization of piezoelectric inkjet printing in the development of sol-gel-based paper biosensors,” according to Brennan, cited in a statement by FujiFilm Dimatix. “Inkjet printing for this application because the system is simple, rapid, scalable, compatible with paper substrates and amenable to pattern formation.”