The waiting is the worst. That time between the doctor taking your blood test and the return of those dreaded results can seem interminable. Once the result has been determined the situation can be faced and dealt with, whether it’s a case of “nothing to worry about” or “you better sit down”. However, scientists may be about to make that wait a thing of the past. Miniaturised, handheld devices called biosensors have the potential to solve this problem by providing on the spot sample analysis, doing away with need for expensive, time consuming laboratory based techniques.
So, how do they work? Biosensors come in many shapes and sizes but they all have two key features. One is a biological recognition element, which allows the detection of the species of interest. The second is a transducer which converts a signal produced by the detection of the species into a signal that can be observed.
For example, a significant amount of research in recent years has gone into the development of a biosensor for the detection of prostate specific antigen (PSA) a biomarker indicative of prostate cancer. These sensors work by using an antibody (the biological recognition element) to detect PSA in conjunction with an electrode which is cable of detecting a measurable electrochemical signal.
In this type of research an arms race is ongoing to achieve greater sensitivity and lower limits of detection with the ultimate goal being single molecule detection. The achievement of this goal is a truly interdisciplinary pursuit with contributions coming from engineers, physicists, chemists and biologists all having a role to play. In particular, so called “wonder materials” such as graphene and carbon nanotubes are playing an increasingly important role. These materials exist on the nanoscale meaning they have features less than 100nM or in other words less than 10000 times the width of a human hair. It turns out than on the nanoscale materials have significantly different properties than their more every-day counterparts. Graphene, for example, is the strongest material known to man yet many layers of graphene make up graphite, the easily breakable ‘lead’ in your pencil. The ability of these materials to allow electrochemical reactions to occur more quickly at their surface is particularly advantageous for sensors, allowing lower limits of detection to be achieved.
So, you may be wondering when you will see these devices actually in use by doctors. The reality is that the majority of sensors never leave a laboratory setting with only a limited number of successes in over 50 years of biosensor research. In fact the sensor that diabetes patients use for monitoring their blood glucose levels (and its various iterations) is by far the most successful commercially available biosensor, accounting for more than 90% of the market. In a recent paper in the journal Angewandte Chemie, Professor George Whitesides of Harvard highlighted this issue by showing that only one in sixty point of care device research papers actually contains a field trial never mind the execution of a commercially available product. Making the transition from the lab to a commercially available device is difficult not only from a scientific standpoint; it also crucially requires significant financial resources. The explosion of research in this area has not led to an explosion of useful products.
So, waiting on test results from your doctor may still be today’s reality but as the technology grows ever more sophisticated this revolution in healthcare might just be around the corner.