Raman keeps blood in the bag

Scientists in Canada have developed a way to monitor biochemical changes in blood donations, without breaking into the bag where they are stored. The technique could eventually be part of a quality control check for blood transfusions.

Research shows that blood changes in storage. Regulations normally require that unused blood be disposed of after 6 weeks. However, blood’s biochemistry is complex and not fully understood, and some donations degrade faster than others.

Numerous methods are available to analyse blood away from their sterile PVC home but the contamination risk means that health care workers do not routinely check blood just prior to transfusion. Now, Michael Blades and Robin Turner and their team at the University of British Columbia, have designed a Raman spectroscopy method capable of non-invasive analysis, which maintains the integrity of the donation.

‘The current regulatory management of red blood cell inventories is based solely on the age of each unit, with no consideration given to natural variability within donors,’ comments team members Chad Atkins and Kevin Buckley. ‘We were interested to investigate the biochemical changes that are known to occur inside red blood cell units with spectroscopy, rather than rely on the proxy measure of age.’

The team’s technique uses spatially offset Raman spectroscopy (SORS) which collects spectra from a location that is ‘offset’ from the laser illumination point. An offset spectrum has a greater contribution of photons diffusing from depths within the sample rather than directly from the surface, so SORS is ideal for studying samples within a container. The team introduced their offset across the plane of the blood sample using the standard beam-steering optics of their Raman microscope. This simple arrangement provided rich information on the red blood cells within the bag.

Rebecca Hopkins a spectroscopy expert from the Defence Science and Technology Laboratory, UK, says, ‘The results show there is potential to monitor biochemical changes in blood without compromising sample sterility and quality. Ultimately, this non-invasive analytical approach could prevent patients from experiencing harmful effects as a result of medical intervention.’

The team now intend to use their technique to probe the metabolic processes occurring within the bag.