Biosensors for real-time monitoring of waterborne pathogens and viability determination

Inadequate access to clean water is hugely detrimental both to economic development and human health. In the developing world 3900 children die daily from diseases transmitted through unsafe water and 1.2 billion people lack access to safe water (1). Even in the developed world, waterborne pathogens can cause huge problems, in terms of both public health and lost productivity. For example, in the past few years cryptosporidiosis outbreaks in the UK have infected hundreds of people and resulted in hundreds of thousands of households being issued with boil water notices (2). As the population continues to grow, increased industrialisation occurs and climate change reduces freshwater supplies, the problem of water scarcity will intensify (1). One of the biggest challenges is to detect the presence of pathogens, especially those present at low level concentrations. The rapid and robust detection of pathogens is required in the water industry to monitor the integrity of existing treatment facilities and in international development to rapidly and accurately obtain analytical data on water quality in the field. A Scottish Water R&D aim is to achieve zero-disruption to the public, while safeguarding drinking water quality. Therefore, rapid and accurate methods to monitor water for pathogen presence are required. Current methods to indicate, e.g. cryptosporidium presence take around 3 days. Furthermore, the method does not indicate viability or species, which is essential information to determine whether the detected oocysts are pathogenic to humans and to decide on appropriate response strategies. The ideal solution would be an online automated detection system linked to methods for rapid determination of species and viability. We propose a novel biosensing approach for more rapid detection of waterborne pathogens with the aim of incorporating sensors into online automated systems. The recognition of the pathogen utilises imprinted polymers, which provide a low-cost and robust alternative to the current antibody-based recognition, and have previously been used to detect benzimidazole in water (3). The signal transduction will be performed by low-cost, wireless magnetoelastic (ME) sensors (4); such sensors have been used to detect pesticides in water (5). The project will investigate various techniques for the synthesis of imprinted polymers, on ME sensors, capable of specific detection of pathogens of interest to the water industry. This project will focus upon cryptosporidium, further work will extend to Giardia and bacteria. While the above technology will indicate pathogen presence, it is extremely desirable to obtain further information about the detected pathogen, e.g. speciation and viability. To provide information about which species of pathogen is present, we will investigate lab-on-a-chip PCR. Microfluidic PCR systems allow for rapid temperature cycling and Zaysteva et al demonstrated an assay of pathogen RNA on a PDMS microfluidic system in just 15 mins (6). Scottish Water have demonstrated 80% successful PCR from one cryptosporidium oocyst, although 24hrs is required for testing. We will study whether similar success rates can be achieved, in considerably shorter timescales, when this protocol is adapted for incorporation into a microfluidic device. 1. Shannon et al, Nature 2008 452 301 2. http://www.cieh.org/policy/cryptosporidium_outbreaks.html 3. Cocha et al, Talanta 2009 78 1029 4. Grimes et al, Sensors 2002 2 294 5. Zourob et al, Analyst 2007 132 338 6. Zaysteva et al, Lab Chip 2005 5 805