ATR Diagnosis

Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) is a powerful technique to study the composition of various samples. It is however particularly promising in the context of diagnostics based on body fluids, such as blood and its derivatives (e.g. serum, plasma). Minimal invasiveness of this approach combined with versatility of the technique, its low cost, simplicity and high speed fit perfectly the requirements for a diagnostic tool. For point-of-care testing, the use of ATR-FTIR enables the analysis of blood in the aqueous state, which represents an enormous advantage by minimising the sample preparation as well as the ability to obtain results within minutes.

ATR-FTIR spectroscopy based diagnosis enables one to detect any anomalies in the blood composition, such as high glucose (Fig.1), unusual secondary structure of protein or presence of foreign organisms (Fig. 2). Our group focuses primarily on the application of ATR-FTIR for the point-of-care testing for:

Malaria
Human Immunodeficiency Virus (HIV)
Hepatitis B and C
Sepsis

The presence of organisms, such as parasites, viruses, bacteria or fungi can be detected through their specific biochemical signatures, related to the presence of nucleic acids (Fig. 3) as well as unique lipid and protein composition. The diversity of individual organisms (and their spectral signatures) among themselves creates a potential for rapid high-precision detection, allowing to determine not only the presence and type of a foreign organism (malaria parasite, virus, bacteria, fungi etc.) but even their specific characteristic (e.g. Gram(+) and Gram(-) bacteria, resistance to antibiotics, etc.).
The project is run in extensive collaboration with Monash Health, Alfred Hospital, Burnet Institute and Victorian Infectious Diseases Reference Laboratory.

Fig. 1. 2nd derivatives of ATR spectra of serum from 24 healthy patients with one presenting abnormally high glucose (20.6). Distinctly different spectral profile allows to easily identify elevated levels of glucose.

Fig. 2. PLS-R regression of RBCs spiked between 0–1% parasitemia, demonstrating the ability for malaria parasite detection, even within low concentration of parasites. Reproduced from [2].

Fig. 3. Spectral series (a) and their second derivatives (b) for pure reference samples: (A) single stranded DNA dehydrating (T-FTIR), (B) single stranded RNA rehydrating (ATR-FTIR), (C) double-stranded DNA dehydrating (T-FTIR), and (D) double stranded DNA dehydrating (T-FTIR). In all spectral series red denotes dehydrated, blue denotes hydrated. Prominent spectral differences between nucleic acids, dependant on their form and hydration. Reproduced from [3].

Related articles:

[1]Khoshmanesh, A., Dixon, M.W., Kenny, S., Tilley, L., McNaughton, D. and Wood, B.R., 2014. Detection and quantification of early-stage malaria parasites in laboratory infected erythrocytes by attenuated total reflectance infrared spectroscopy and multivariate analysis, Analytical chemistry, 86(9), pp.4379-4386.
[2]Martin, M., Perez-Guaita, D., Andrew, D.W., Richards, J.S., Wood, B.R. and Heraud, P., 2017. The effect of common anticoagulants in detection and quantification of malaria parasitemia in human red blood cells by ATR-FTIR spectroscopy, Analyst, 2017, DOI: 0.1039/C6AN02075E.
[3]Wood, B.R., 2016. The importance of hydration and DNA conformation in interpreting infrared spectra of cells and tissues, Chem. Soc. Rev., 45(7), pp.1980-1998.