Optical Biosensor for Continuous Rapid Detection of Health Threats

Researchers from Stratophase, a firm out of Southampton, United Kingdom, just published a paper in journal Biosensors and Bioelectronics, describing the technology inside their SpectroSens chip, a new optical micro device designed to rapidly detect pathogens and biochemicals. The chip can be loaded into a robust device to simultaneously identify 16 different potential health threats like anthrax and ricin toxin.

The chip works with light that reflects in different wavelengths in different situations. The reflectors, which are called Bragg gratings, will reflect one wavelength and let all other wavelengths pass through unaffected. The specific color it reflects can be correlated with a location on the chip. Interactions between target antigens in the test sample and respective immobilized antibodies on the chip result in localized changes in the refractive-index. This increases the wavelength of the reflected light which can be detected. With one chip it is possible to multiplex sixteen different biological agents like spores, viruses and toxins in real-time. You can either load samples manually or, when continuous monitoring is necessary, the cartridge can be combined with air sampling technology.

The company tested the device first on harmless biological agents like Bacillus atrophaeus (BG) spores, Escherichia coli, MS2 viruses and albumin protein. Thereafter, they tested the method on organisms like Bacillus anthracis (BA) spores, Vaccinia viruses (heat-killed) and ricin toxin. The soluble protein antigens seem to give a higher and earlier response than the larger bacterial and viral antigens, but in the end all were picked up by the detector.

The disposable microchips and robust device are compact and easy to transport, which makes them ideal to do rapid on-site monitoring. The system can be used in security and defense operations, but also in regular in-field medical diagnostics for human and veterinary health.

The paper is in press but is currently available for online purchase through Science Direct.

Optical microchip array biosensor for multiplexed detection of bio-hazardous agents.

D. Bhatta, A. Michel, M. Marti Villalba, G.D. Emmerson, I.J.G. Sparrow, E.A. Perkins, M.B. McDonnell, R.W. Ely and G.A. Cartwright. Biosensors and Bioelectronics. Volume 28, Issue 2. 2011.

Abstract

An optical waveguide array biosensor suitable for rapid detection of multiple bio-hazardous agents is presented. SpectroSens™ optical microchip sensors contain multiple spatially-separated waveguide channels with integral high-precision Bragg gratings sensitive to changes in refractive-index; selective surface-functionalisation of discrete sensing channels with different antibodies as bio-recognition elements enables selective multi-analyte biological detection. Interactions between target antigens in the test sample and respective surface-immobilised antibodies result in localised changes in refractive-index; the biosensor response manifests as increases in wavelength of light reflected from specific sensing channels. Multiplexed, label-free detection of 8 different biological agents, encompassing bacterial spores, vegetative cells, viruses and proteinaceous toxins has been demonstrated in real-time. Selective detection of Bacillus atrophaeus (BG) spores, Escherichia coli cells, MS2 viruses and ovalbumin (OVA) protein (simulant bio-hazardous agents) was first demonstrated as proof-of-concept; subsequently, detection of Bacillus anthracis (BA) spores (UM23CL2 strain), Franciscella tularensis (FT) cells (live vaccine strain), Vaccinia viruses (heat-killed) and ricin toxin (bio-hazardous agents) was proven. Two optical microchip sensors, each comprising 8 sensing channels were packaged into a single disposable cartridge allowing simultaneous 16-channel data acquisition. The specific antibody deposition sequence used in this study enabled detection of either 4 simulants or 4 bio-hazardous agents using a single consumable. The final device, a culmination of the multidisciplinary convergence of the fields of biology, chemistry, optoelectronics and microfluidics, is man-portable and inherently robust. The performance characteristics of the SpectroSens™ technology platform highlight its potential for exploitation as a ‘detect to warn/treat’ biodetector in security and defence operations.