The observation that the malaria parasite, when in a human host, produces haemozoin as part of the natural disease cycle led to the development of the CMD technology.
With the support of £2 million of funding from European Framework Programmes and The Bill & Melinda Gates Foundation, the magneto-optic response of haemozoin, found in the blood of malaria patients, was exploited to demonstrate the diagnostic utility of the technique. These programmes delivered a portable, near commercial prototype diagnostic device targeted for use without laboratory support in the most remote regions. This, and earlier prototypes validated the sensing principle during clinical testing against gold standard microscopy at field stations across Africa and Asia. Involving more than 1,000 patient samples, these studies demonstrated the ability to detect haemozoin in lysed finger-prick samples of whole blood – at the point-of-need – in less than five minutes.
CMD’s core technology is an innovative and proprietary magneto-optical sensing system that exploits changes in the rotational behaviour of magnetic reporters, which occur either naturally as a marker of a disease or are artificially introduced as an assay component, observed via the Cotton Mouton magneto-optic effect.
The Cotton-Mouton Effect
The Cotton-Mouton Effect (CME) is a little known consequence of the application of a magnetic field to liquids or gases such that light travelling in these media experiences a change in optical behaviour. For most liquids the CME is extremely small however introducing populations of magnetic nanorods into the fluid greatly enhances the effect.
When fluids containing magnetic nanorods are exposed to a magnetic field the reporters first align and then rotate with the field (a / b). Their rotation, observed optically, is a function of both field frequency and the drag imposed upon them by their surroundings. When a molecular target, such as a protein or nucleic acid, binds to a specific receptor immobilised on the reporter’s surface (c / d), the drag increases and a change in rotation occurs. This is measured optically, with very high precision.
By customising the optical properties of different populations of nanorods, it is possible to ‘tune’ each population to a particular frequency of light. This allows their optical properties to be observed independently yet simultaneously, thus enabling the detection of multiple markers.
Patents covering the use of the platform for the diagnosis of malaria have been granted in the US and China and are under examination in Europe and India. A patent application covering the extension of the technology to the detection of generic infectious agents has been filed and is under examination.