Magnetic field enriched surface enhanced resonance Raman spectroscopy for early malaria diagnosis

Abstract

Hemozoin is a by-product of malaria infection in erythrocytes, which has been explored as a biomarker for early malaria diagnosis. We report magnetic field-enriched surface-enhanced resonance Raman spectroscopy (SERRS) of β-hematin crystals, which are the equivalent of hemozoin biocrystals in spectroscopic features, by using magnetic nanoparticles with iron oxide core and silver shell (Fe(3)O(4)@Ag). The external magnetic field enriches β-hematin crystals and enhances the binding between β-hematin crystals and magnetic nanoparticles, which provides further improvement in SERRS signals. The magnetic field-enriched SERRS signal of β-hematin crystals shows approximately five orders of magnitude enhancement in the resonance Raman signal, in comparison to about three orders of magnitude improvement in the SERRS signal without the influence of magnetic field. The improvement has led to a β-hematin detection limit at a concentration of 5 nM (roughly equivalent to 30 parasites/μl at the early stages of malaria infection), which demonstrates the potential of magnetic field-enriched SERRS technique in early malaria diagnosis.

Application of nanodiagnostics in point-of-care tests for infectious diseases

“…As a successful example, the magnetic nanoparticles with iron oxide core and silver shell have been demonstrated for the efficient and early diagnosis of malaria, an infectious disease. 53 These magnetic nanoparticles showed an ability to detect β-hematin crystals, an equivalent of hemozoin biocrystals, through the magnetic field-enriched surface-enhanced resonance Raman spectroscopy. The hemozoin has been recognized as a biomarker for malaria infection, and could be used for early diagnosis of malaria.…”

Malaria diagnosis for malaria elimination

“…A number of recent studies have reported on strategies to exploit physical and/or electromagnetic features of hemozoin crystals to detect infection by malaria parasites [54,[80][81][82][83][84][85][86]. Generally, the LOD of these methods is between 1 and 30 iRBCs/ml and, therefore, not as sensitive as NAA strategies.…”

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

“…A holographic grating (1800 gr/mm) dispersed the signal into a Rem Cam CCD detector (inVia, Renishaw, Gloucestershire, UK) for analysis. The spectral resolution was 2 cm -1 and integration time was 10 s. These raw data underwent the baseline correction, followed by averaging over a five-point window to reduce noise and removal [13] of fluorescence background, which yielded the final spectra shown in the Results section.…”

“…These spectra were averaged from five different locations with a signal standard deviation of less than 5%. Prominent Raman peaks located at about 615, 775, 1185, 1310, 1365, and 1508 cm -1 , which can be attributed to the C-C-C ring in-plane bending, CH out-of-plane bending, C-O-C stretching, C-C/C-N stretching and aromatic C-C stretching, respectively [13,18], are observed in the R6G Raman spectra measured using the microneedle based SERS probe [ Figure 2(a) and (b)]. In contrast, the ordinary Raman spectra of R6G at higher concentrations show only weak Raman peaks even at a higher excitation power of 100 mW.…”