Raman spectroscopy and its analogues, surface enhanced (resonance) Raman scattering (SERS and SERRS) have been widely applied in malaria research to target early diagnosis of malaria infection in blood or plasma samples primarily via the identification of the infection specific biomarker hemozoin. However, the capability of Raman spectroscopy to contribute to tackling other areas of malaria research is not as thoroughly investigated. In this work two such areas were studied. The first looked to utilise Raman spectroscopy to differentiate malaria parasite infected tissue from non-infected and the second investigated coupling portable Raman with malaria diagnostic tests to improve detection levels.Research commenced by investigating the potential of Raman spectroscopy to detect tissue burden within malaria infected samples. Sequestration of parasite infected red blood cells in the vascular endothelium is associated with features of severe malaria pathology such as cerebral malaria. Currently, there is difficulty in assessing the presence of parasites sequestered within tissue during the progression of the infection, with many reported studies carried out post-mortem. Raman imaging coupled with chemometric analysis showed very clear separation of malaria infected mice spleen sections from non-infected, with an associated increase in concentration of heme-based Raman vibrations within the infected data set. An in-vivo mouse study also highlighted the ability of Raman spectroscopy to gain biological information from whole organs. These results demonstrated that Raman spectroscopy can be used to easily discriminate the subtle changes in tissue burden upon malarial infection within tissue sections.Finally, the coupling of rapid diagnostic tests with a handheld portable Raman spectrometer for the detection of HRP-II malaria biomarker via SERRS was investigated.By applying a 3D-microfluidic paper-based device in a sandwich assay format, SERRS detection gave a theoretical LoD of 1.68 ng/mL HRP-II which converted to ~22 parasites/μL (~0.00044 % parasitemia). This detection limit of infection density was lower than what is typically capable of a technician analysing a blood smear by light microscopy (~100 parasites/μL, 0.002 % parasitemia), which is a current gold standard detection method. The results displayed the advantages of high sensitivity and specificity gained from SERRS and as it was conducted on a portable Ramanspectrometer it has the potential to be implemented as a point-of-care method. This coupling could be applied to enhance the detection capabilities of the already widely applied rapid diagnostic tests. The possibility of being able to reliably detect lower density parasitemia with this SERRS-3D-μPAD could also allow positive malaria identification in asymptomatic individuals.
|Date of Award||1 Nov 2018|
- University Of Strathclyde
|Sponsors||University of Strathclyde|
|Supervisor||Duncan Graham (Supervisor) & Karen Faulds (Supervisor)|