SERS-based rapid diagnostics for the detection of biomarkers associated with sepsis

  • Emma O'Connor

Student thesis: Doctoral Thesis


Worldwide, approximately 11 million people lose their lives to sepsis every year, primarily due to the condition being extremely difficult to diagnose. Therefore, early detection of sepsis is crucial for improved patient outcomes and lower mortality rates.;In this investigation, a surface enhanced Raman scattering or SERS-based rapid diagnostic platform was developed for the multiplexed detection of biomarkers associated with sepsis. Two biomarkers, C-reactive protein (CRP) and interleukin-6 (IL-6) were detected using a lateral flow immunoassay (LFIA) device combined with SERS-active gold nanoparticles. For CRP, a limit of detection (LOD) of 8 ng/mL was achieved using a portable, handheld Raman spectrometer and these results were comparable to using a benchtop microscope instrument. Additionally, the results showed that SERS was more sensitive than visible RGB analysis. The assay was also capable of semi-quantitative detection of CRP in spiked human plasma samples with a calculated LOD of 5.4 μg/mL using the handheld instrument. CRP concentrations exceeding 10 μg/mL are indicative of a disease state.;A LOD of 10.5 ng/mL was calculated for singleplex IL-6 detection. Multiplex detection of both CRP and IL-6 was also achieved on a single LFIA device using both spatially resolved and signal-resolved SERS analysis. The signal-resolved duplex detection assay, where handheld SERS analysis was performed on a single test region, was capable of quantitative detection of both biomarkers simultaneously and LODs of 7.5 ng/mL and 14.1 ng/mL were calculated for CRP and IL-6 respectively.;Additionally, the optimisation of a 3D microfluidic paper-based diagnostic, or μPAD, device for use with a SERS-based immunoassay was investigated. The flexible design of 3D μPADs offers excellent potential for multiplexing. Quantitative detection of CRP using this rapid diagnostic device was achieved however, the results showed the SERS-based LFIA was superior to the 3D μPAD for detection of CRP and IL-6.;Overall, this work has demonstrated the viability of a SERS-based LFIA rapid diagnostic, combined with a handheld Raman spectrometer, for the portable, multiplexed and fast detection of biomarkers associated with sepsis at the point-of-care.
Date of Award8 Jan 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorKaren Faulds (Supervisor) & Duncan Graham (Supervisor)

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