Paper test can detect Ebola
With cases of Ebola having now spread to New York, scientists in America have now developed a cheap and simple test which could be used on the virus. It uses just a piece of paper and gives an answer in under 20 minutes.
The Harvard-based team found that cells in a dish can be engineered to make them undergo a colour change when they come into contact with the genetic material of Ebola.
If these cells are then broken apart and freeze-dried onto pieces of paper, all of the chemical machinery of the cells remains intact and stable for long periods at room temperature. To make it active again, you just add water, which can be in the form of a sample from a patient.
Chris Smith spoke to Jim Collins, who discovered the technique...
Jim - What we specifically have done is, created now sensors that can detect the presence of, for example, antibiotic resistance with the presence of pathogens including viral pathogens. You could take a sample from a patient, spot them on a paper disk that's been prepared with our material and see if it changes colour. If it changes colour for example from yellow to purple, that indicates that you may have a resistant bacterial infection or you may be infected with a certain virus.
Chris - This means presumably, you could use some of the components in the cells to do for instance, paper-based tests or to do chemical reactions on a piece of paper that would be really easy to store and transport.
Jim - That's correct. What we discovered is that you can take the materials inside a living cell, spot it on paper, we'll flash freeze them and you now have your prep. We can store them. Keith had stored these for many, many months in his desk drawer. He can then take them out. We then would just rehydrate them with something as simple as water and either have a trigger that might be a molecular component that we want to detect or chemical that we want to detect in order to see if something is present and/or to initiate the reactions with the machinery that are spotted on this paper disk.
Chris - Now, turning to something which is dominating the headlines all over the world and has done for a number of months now, that's the Ebola crisis. One of the really big frustrations for people working in West Africa is the lack of rapid testing facilities. Could you take what you're doing here and produce a piece of impregnated paper so that people would have a rapid diagnostic for Ebola cases?
Jim - In principle, yes. As one of our proof of principle demonstrations in our paper, what we did was, in a matter of just 12 hours, develop 24 different sensors using some of the engineered machinery that we invented to detect an element of the virus that will be produced. Our system could give you a readout in 20 to 25 minutes. They cost just pennies and these sensors could detect very low amounts of the virus. Now mind you, at present, this is an academic exercise. This platform is not yet ready to be distributed into the field and used in clinics around the world, but we are confident that this could eventually form the basis of a rapid diagnostic test for various pathogen outbreaks including Ebola.
Chris - What is the output? In other words, when you do say, a pregnancy test, everyone knows they're looking for blue lines on a white background, when you run one of your tests, how do you know what is a positive and what is a negative?
Jim - It depends on the system that we setup, but the one they were most commonly using is, we have developed a sensor that when it turns on, it would produce an enzyme that will change the paper colour from yellow to purple.
Chris - Could you also use it to look at the body's own biochemicals? For instance, could you do a test on somebody to see if they had X level of something in their body or they were carrying a gene which gave them risk of Y disease?
Jim - Yes, so going beyond just say, infectious disease applications, we've shown already that you can use this to for example, sense physiological levels of glucose in a given sample. We're able to spot and already engineered glucose sensor onto paper and have it function in response to very low amounts of glucose and actually give you a readout of how much glucose is present. One could also envision using this in order to sense and diagnose the presence of complex diseases such as cancer.