Aptamer-based surface-enhanced resonance Raman scattering assay on a paper fluidic platform for detection of cardiac troponin I

Abstract

Significance: Cardiac troponin I (cTnI) is a primary biomarker for diagnosis of myocardial infarction (MI). In contrast to central laboratory tests for cTnI, point-of-care (POC) testing has the advantage of providing results when the patient is first encountered, which helps high-risk patients to be treated more rapidly and low-risk patients to be released in a timely fashion. A paper fluidic platform is good for POC testing because the paper is abundant, low cost, and disposable. However, current cTnI assays on paper platforms use antibodies as the recognition element, which has limitations due to the high cost of production and antibody stability issues at the POC. Aim: To develop an aptamer-based assay on a paper strip using surface-enhanced resonance Raman spectroscopy (SERRS) for detection of cTnI in the clinically relevant range at the POC. Approach: Gold nanoparticles (AuNPs) were functionalized with a Raman reporter molecule, malachite green isothiocyanate. The functionalized AuNPs were encapsulated in a silica shell and provided a SERRS signal using a handheld Raman system with a 638-nm excitation wavelength. A primary aptamer and a secondary aptamer of cTnI were used in a sandwich assay format to bind the cTnI on a test line of a paper fluidic platform. By measuring the SERRS signal from the test line, the concentration of cTnI was quantitatively determined. Results: The aptamer-based SERRS assay on a paper strip had a detection range of 0.016 to 0.1 ng∕ml for cTnI, had good selectivity for cTnI compared to three other markers, had good stability over 10 days, and had good performance in the more complex serum sample matrix. Conclusions: The aptamer-based SERRS assay on a paper strip has the potential to provide a sensitive, selective, stable, repeatable, and cost-effective platform for the detection of cTnI toward eventual use in diagnosis of MI at the POC.

Cardiac Troponin Biosensor Designs: Current Developments and Remaining Challenges

“…( b ) Digital images of the paper-based fluidic platforms and ( c ) SERRS spectra from the test lines after the capture of different concentrations of cTnI via MGITC monitoring. Figure adapted from Tu et al [ 52 ].…”

“…Later on, the authors progressed to the multiplexed detection of the three biomarkers on the same test line [51]. The reported assay schematically illustrated in Figure 4a Similar to the above described biosensing device, Tu et al reported the successful fabrication of a paper-based fluidic platform for the sensitive and specific detection of cTnI by integrating aptamers instead of antibodies as molecular recognition elements [52]. The T-line was conjugated with the specific cTnI primary aptamer whereas on the C-line, the reverse complementary single-stranded DNA of the cTnI secondary aptamer was immobilized.…”

Raman Scattering-Based Biosensing: New Prospects and Opportunities

“…As noted above, at the moment, there is only one example of the development Modification of the SERS nanotag with bioreceptor molecules that specifically bind the analyte gave rise to the development of SERS-based biosensors. To date, many successful studies have been published on the use of SERS nanotags in bioimaging and biosensors [84][85][86]. However, to date, the only example of the indirect detection using the SERS nanotag in nonlinear Raman spectroscopy has been described.…”

Progress, Opportunities, and Challenges of Troponin Analysis in the Early Diagnosis of Cardiovascular Diseases

“…Beyond the above-discussed types, other techniques have been trialed for troponin analysis including a SERS-based techniques, membrane assisted force differentiation assays, etc. For example, Chang et al developed a membrane assisted force differentiation assay for cTnI via coupling an antibody functionalized nanoporous membrane with superparamagnetic beads.…”