Despite a swathe of new biosensor technology developments, water companies remain reluctant to adopt these novel approaches. Professor Richard Luxton explains why this could soon change.
Detecting water-borne pathogens with biology
There are a remarkable range of biosensing technologies under development. While each is unique, they all rely on an interaction between a biological material and some external influence which thus becomes detectable.
Typically, they integrate electronics with biological molecules such as antibodies or enzymes to measure biological elements within a system. They may also be used to detect the influence of chemicals, such as pesticides or other toxic materials.
Biological molecules can interact with certain proteins found on the walls of, say, E.coli to provide a method of detection, for instance. Once an interaction takes place, a variety of different techniques have been developed to allow that to be recorded and measured.
Electronics may be used to detect a change in charge or impedance for example, but other biological or physical phenomena may also be employed such as fluorescence or luminescence.
Water technology firm Modern Water, for example, uses bioluminescent bacteria to perform biosensor testing for the detection of toxic substances. Certain strains of bacteria naturally emit light, but when exposed to toxic substances the amount of emitted light is reduced. The greater the toxicity of the sample, the bigger the impact.
“There is a whole variety of different capture molecules including enzymes. You can capture lots of different things with antibodies for example.”
Similarly, surface plasmon resonance (SPR) is a technique which measures a change in the refractive index of the surface of a sensor which occurs when a particular molecule binds to it.
“There is a whole variety of different capture molecules including enzymes. You can capture lots of different things with antibodies for example,” explains Professor Ricard Luxton of the Institute of Biosensing Technology at the University of the West of England.
Advancing biosensor technology
There are a number of new developments underway in this field which are expanding the capabilities of biosensors.
Speaking to Aquatech Online, Luxton says: “There are these newer capture molecules, aptamers, which are short sequences of DNA folded in a particular way that act like an antibody so they recognise something through their shape.”
There are a number of other molecules such as affimer proteins, as well as modified bacteria that are being used to develop new systems to capture biological indicators.
“Some of these new things like the aptamers and affimers are molecularly modified or newly created molecules, so they are novel and they’ve been designed to bind to particular targets within the environment. There is quite a bit of new technology that has been integrated into these sensor systems,” says Luxton.
Alongside the biological elements through novel molecules and modified bacteria, another key area for biosensor development comes from the use of novel materials to improve sensitivity and allow far smaller concentrations to be detected.
“We're aiming to get is something which you can put in the water in the reservoir that doesn't need any maintenance, makes a measurement and then communicates that to the web."
“These days researchers are using materials like graphene and other nanomaterials to make the sensors a lot more sensitive both through the sensor surface and the application of these novel materials with capture systems,” says Luxton.
Barriers to adoption
Communications technologies are also being deployed that allow detectors to alert users quickly as well as networking sensors together to give information about a developing situation such as a geographical spread.
“What we're aiming to get is something which you can put in the water in the reservoir that doesn't need any maintenance, a target molecule binds to the surface of a sensor and makes a measurement which is then integrated with the technology to communicate information to the web,” notes Luxton.
Although offering considerable benefits to water treatment and supply entities, there are a number of barriers that are slowing the widespread adoption of biosensor technologies in the water sector.
Examples include the long investment cycles associated with the water industry, as well as the natural conservatism that comes from an industry so intimately concerned with public health.
“We're at a point where pretty much now the technology is there and some of the field trials have been done for some of these sensor systems,” says Luxton. “The challenges are the adoption of the technologies, the cost of fabrication and scalable manufacture to make it worthwhile,” he adds.
“They've got a lot of investment in existing instrumentation and some of these new technologies work in completely different ways, you have got to work within budgets and understand how expensive it would be to introduce new technology, it's quite a complex picture.”
While water supply companies certainly do have research budgets these are typically used on the evaluation of technologies rather than primary development. As a result, water companies are expected to bring in tried and tested technologies from established and reliable third-party players.
It is these supply companies that are potentially working with universities and research institutes in transforming novel biosensor technologies into cost-effective, practical and deployable sensors.
However, global events may be about to transform the biosensor sector and rapidly accelerate their adoption and deployment.
Not only do biosensors have the capabilities to be far more sensitive than current techniques when it comes to detecting the presence of certain molecules but, like vaccines they can be readily adapted and modified to detect new and emerging threats such as the novel coronavirus.
As Luxton observes: “For the newer viruses and such like you have got to be using these techniques because the traditional methods don't actually measure them quickly or easily.”
Consequently, if water companies are looking for these new emerging threats, they have to look at how to produce the appropriate detection technology and for many issues the best solution is the application of biosensors.
- The latest advances in biosensors will be explored in more detail during a forthcoming webinar hosted by the Sensors for Water Interest Group (SWIG) to be held on 28 April. For more information please visit here.
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