Keywords: paper, pesticide, sensors
Some researchers have developed a paper-based sensor that automatically changes color to detect pesticide-pesticide organofosfat and acetylcholinesterase inhibitors (Ache) others in the food and beverage samples. John Brennan and his colleagues at McMaster University Canada has made a reagent-free devices that detect simple pesticides nanomolar amounts within five minutes on the samples such as milk and lettuce.
Paper is a very interesting material for analytical devices because of relatively cheap, abundant, and can move the working fluid by capillary without external power. Recent focus on diagnostic platforms based on changes in color and paper-based has arisen because of such platforms can be used in locations where there are limited resources.
Tim Brennan uses Ache as a reporter because it is inhibited by pesticides such as organofosfat and karbamat. "Organofosfat still used in developing countries for the spraying of agricultural crops," said Brennan. "Ache-based sensors have the potential for rapid inspection organofosfat in the field."
Change colors obtained using paper-based sensors is clearly a proof of concept studies above, and occurs in seconds.
Piezoelectric inkjet print used for mendeposisikan reagents on paper-based foundation for the preparation of the use, so that additional reagents are not required at the time of analysis. Ache and a substrate that changes color, indofenil acetate (IPA), was framed in two separate zones on the piece of paper 1 x 10 cm by using the links from the silica sol-gel biokompatibel, the enzyme is trapped in a zone of sensors and science stored in the substrate zone.
To test a sample, the end of the paper sensor is placed in the sample solution, which flows through the capillaries into the work-sensing zone where he left berikunbasi. Furthermore, the other end of the sensor immersed into distilled water so that the flow in the opposite direction of pressing science into the substrate zone-sensing area. There, Ache hydrolyze IPA, to form the color change from yellow to blue. The intensity of blue color was observed (either with the naked eye or with a digital camera) is inversely proportional to the amount of pesticides found in the sample. Brennan said the approach of two-way flow is greatly enhanced detection limits due to possible analit-analit berinkubasi in Ache sensing zone before science came.
This research team tested the method on real foods such as milk and apple juice that has been laced with pesticides and found that the effective paper-based sensors to detect contaminants. When they tested undelete taken from apple sprayed with pesticides, paper-based test results comparable with conventional mass spectrometry methods.
"Test analit less competitive which, rather than increases, the signal typically still less explored for these tests compared to paper-based direct test," said Samuel Sia of biomedical engineering at Columbia University, U.S..
The researchers hope that their approach could be used for screening runut elements of pesticides in the environment and food samples-smpel in the field. However, although these devices have an active period of at least one month if stored at 4oC, Sia stressed that this can still be a stumbling block in some situations, for storage at 4oC "not feasible in most areas located in remote areas".
Adapted from: chemistryworld