Handheld Raman Spectrometer Instrumentation for Quantitative Tuberculosis Biomarker Detection: A Performance Assessment for Point-of-Need Infectious Disease Diagnostics

Abstract

Techniques for the detection of disease biomarkers are key components in the protection of human health. While work over the last few decades has redefined the low-level measurement of disease biomarkers, the translation of these capabilities from the formal clinical setting to point-of-need (PON) usage has been much more limited. This paper presents the results of experiments designed to examine the potential utility of a handheld Raman spectrometer as a PON electronic reader for a sandwich immunoassay based on surface-enhanced Raman scattering (SERS). In so doing, the study herein used a recently developed procedure for the SERS detection of phospho-myo-inositol-capped lipoarabinomannan (PILAM) as a means to compare the performance of laboratory-grade and handheld instrumentation and, therefore, gauge the utility of the handheld instrument for PON deployment. Phospho-myo-inositol-capped lipoarabinomannan is a non-pathogenic simulant for mannose-capped lipoarabinomannan (ManLAM), which is an antigenic marker found in serum and other body fluids of individuals infected with tuberculosis (TB). The results of the measurements with the field-portable spectrometer were then compared to those obtained for the same samples when using a much more sensitive benchtop Raman spectrometer. The results, albeit under different operational settings for the two spectrometers (e.g., signal integration time), are promising in that the limit of detection found for PILAM spiked in human serum when using the handheld system (0.18 ng/mL) approached that of the benchtop instrument (0.032 ng/mL). This work also: (1) identified potential adaptations (e.g., optimization of the plasmonically enhanced response for measurement by the handheld unit through a change in the excitation wavelength) to tighten the gap in performance; and (2) briefly examined the next steps and potential processes required to move this immunoassay platform closer to PON utility.

Surface‐enhanced resonance Raman scattering for the sensitive detection of a tuberculosis biomarker in human serum

“…Building on our previous reported work examining the utility of handheld Raman instrumentation, we have begun to incorporate the SERRS assay design within the framework of a vertical flow style assay as a means to transition this technique from the laboratory toward PON diagnostic applications. Although further testing will be required, we believe the combination of these technologies represents a significant step forward in realizing the goal of a highly sensitive PON disease diagnostic platform . This ongoing work will be reported elsewhere.…”

“…Although the extent of branching varies, ManLAM consists of a phosphatidylinositol mannoside anchor linked to a mannan backbone further extended by an arabinan domain with terminal mannose oligosaccharide caps . We have also reported on how the incorporation of new handheld Raman spectrometers in the measurement hardware has the potential to facilitate the transition of this SERS immunoassay from the research laboratory to a PON platform . This paper continues to expand on this body of work by demonstrating the application of the SERRS immunoassay to quantitate levels of ManLAM in human serum.…”

Recent Advancement in the Surface-Enhanced Raman Spectroscopy-Based Biosensors for Infectious Disease Diagnosis

“…SERS-based diagnostic methods using clinical samples have also been conducted to determine the applicability towards POC applications [78][79][80][87][88][89][90]. Porter's group reported a novel sandwich SERS immunoassay for an antigenic biomarker for tuberculosis found in bodily fluids using a handheld Raman spectrometer [90]. They used serum samples to detect phospho-myo-inositol-capped lipoarabinomannan (PILAM), a stimulant of an antigenic biomarker found in tuberculosis infected patients.…”

“…In comparison to proteins and nucleic acids, cellular metabolites are not yet a common biomarker for SERS-based pathogen detection [74,77,78,83,87,90]. Metabolic processes can differ between bacteria that cause infections, therefore certain metabolites are targeted for increased specificity.…”

“…Extensive background knowledge of the bacterium is necessary to understand the proper sample preparation and where the largest concentration of the metabolite resides. Sample fluids for metabolite detection of a bacterial pathogen can vary, ranging from clinical sputum, cerebrospinal fluid (CSF), to blood samples [74,78,90]. Sample preparation for metabolites can be challenging.…”