Portable, multi-modal Raman and fluorescence spectroscopic platform for point-of-care applications

Abstract

. Significance Point-of-care (POC) platforms utilizing optical biosensing strategies can achieve on-site detection of biomarkers to improve the quality of care for patients in low-resource settings. Aim We aimed to develop a portable, multi-modal spectroscopic platform capable of performing Raman and fluorescence measurements from a single sample site. Approach We designed the spectroscopic platform in OpticStudio using commercial optical components and built the system on a portable optical breadboard. Two excitation and collection arms were utilized to detect the two optical signals. The multi-modal functionality was validated using ratiometric Raman/fluorescence samples, and the potential utility was demonstrated using a model bioassay for cardiac troponin I. Results The designed spectroscopic platform achieved a spectral resolution of across the Raman detection range (660 to 770 nm). The ratiometric Raman/fluorescence samples demonstrated no crosstalk between the two detector arms across a gradient of high molar concentrations. Testing of the model bioassay response showed that the integrated approach improved the linearity of the calibration curve from ( ) for the Raman only and ( ) for the fluorescence only to ( ) for the multi-modal approach. Conclusion These findings demonstrate the potential impact of a multi-modal POC spectroscopic platform to improve the sensitivity and robustness necessary for biomarker detection.

Biomarkers and optical based biosensors in cardiac disease detection: early and accurate diagnosis

“…Using Raman spectroscopy not only can we develop noninvasive and label-free vibrational optical-based biosensors but also innovative point-of-care (POC) devices can be designed for clinical diagnosis of cardiovascular diseases. 123 Numerous works have been conducted to detect the cTnI cardiac biomarker in MI-related patients. To achieve low LOD, researchers prepared optical microspheres using silver nanoparticles.…”

Rational design enabling aptamer‐based sensors for surface‐enhanced Raman detection of small molecules

“…Separating the functions into two strands makes the mechanism highly adaptable, which simply requires the modification of the aptamer sequence and its complementary sequence. Another example has been shown recently by Soliman et al that demonstrates an OFF‐to‐ON duplex aptamer mechanism for detection of cardiac troponin I—in the previous examples, the Raman reporter leaves the SERS‐active surface, resulting in a signal OFF or reduction of signal 30 . Although these works show that aptamers can be applied in homogeneous SERS sensing applications, there is still a lack of a clear understanding of how these homogeneous SERS sensors can be designed to take advantage of the duplex aptamer mechanism.…”

“…In some sensors, the duplex is complementary to the aptamer, 27 whereas in others the duplex is hybridizing on additions to the strand outside of the aptamer sequence 28 . In addition, the complementary strand was functional only in one application of these sensors to generate a sensitive OFF‐to‐ON mechanism 30 . Without design rules or a design protocol for these sensors, we would not be able to fully take advantage of the adaptability of this approach to focus on new targets and applications (e.g., environmental analysis).…”

“…Another example has been shown recently by Soliman et al that demonstrates an OFF-to-ON duplex aptamer mechanism for detection of cardiac troponin Iin the previous examples, the Raman reporter leaves the SERS-active surface, resulting in a signal OFF or reduction of signal. 30 Although these works show that aptamers can be applied in homogeneous SERS sensing applications, there is still a lack of a clear understanding of how these homogeneous SERS sensors can be designed to take advantage of the duplex aptamer mechanism. In some sensors, the duplex is complementary to the aptamer, 27 whereas in others the duplex is hybridizing on additions to the strand outside of the aptamer sequence.…”

“…28 In addition, the complementary strand was functional only in one application of these sensors to generate a sensitive OFF-to-ON mechanism. 30 Without design rules or a design protocol for these sensors, we would not be able to fully take advantage of the adaptability of this approach to focus on new targets and applications (e.g., environmental analysis). Furthermore, design rules are particularly important for environmental applications because they can be used to translate the mechanism to different environmental conditions (e.g., temperature or salt concentration) by predicting changes in thermodynamics involved in the mechanism, without having to redesign the sensor via a trial-and-error approach.…”