A portable microfluidic fluorescence spectrometer device for γ-H2AX-based biological dosimetry

Following a radiological incident the rapid identification of those individuals exposed to critically high radiation doses is important for initial triage and medical treatment. It has been previously demonstrated that scoring of radiation-induced foci of the phosphorylated histone γ-H2AX, which form at the sites of DNA double-strand breaks, may be used to determine radiation exposure levels from blood samples. Although faster than the ‘gold standard’ dicentric assay, foci scoring is still impractical in a field situation where large numbers of people may need to be screened. To deal with such a situation, an inexpensive portable device with high throughput capacity is desirable. Here we describe a portable microfluidic fluorescence spectrometer device which passes a suspension of γ-H2AX immunofluorescence-stained lymphocytes through a focused 488 nm laser beam in a microfluidic chamber and records emission spectra over the range 495–725 nm. The recorded emission spectra are spectrally unmixed into their constituent parts from which radiation exposure levels are determined. Proof of principle is demonstrated using cultured lymphoblastoid cells, exposed to X-ray doses between 0 and 8 Gy. With the current prototype setup it takes approximately 6 min to acquire and analyse 10,000 spectra. Further effort is required to fully develop this approach into a portable triage tool that could be used to help classify people into appropriate treatment categories based on radiation exposure levels.