SERS-Based Immunoassay of Myocardial Infarction Biomarkers on a Microfluidic Chip with Plasmonic Nanostripe Microcones

Abstract

We developed a new plasmonic nanostripe microcone array (PNMA) substrate-integrated microfluidic chip for the simultaneous surface-enhanced Raman scattering (SERS)-based immunoassay of the creatine kinase MB isoenzyme (CK-MB) and cardiac troponin (cTnI) cardiac markers. The conventional immunoassay usually employs a microtiter plate as the solid capture plate to form the immunocomplexes. However, the two-dimensional (2D) surface of the microtiter plate limits the capture efficiency of the target antigens due to the steric hindrance effect. To address this issue, a gold film-coated microcone array with nanostripes was developed that can provide a large surface area for capture antibody conjugation and serve as a SERS-active substrate. This unique nano–microhierarchical structure showed an excellent light trapping effect and induced surface plasmon resonance to further enhance the Raman signals of the SERS nanoprobes. It significantly improved the sensitivity and applicability of SERS-based immunoassay on the microfluidic chip. With this integrated microfluidic chip, we successfully performed the simultaneous detection of CK-MB and cTnI, and the detection limit can reach 0.01 ng mL–1. It is believed that the PNMA substrate-integrated microfluidic chip would play a critical role in the rapid and sensitive diagnostics of cardiac diseases.

One‐Stop Plasmonic Nanocube‐Excited SERS Immunoassay Platform of Multiple Cardiac Biomarkers for Rapid Screening and Progressive Tracing of Acute Myocardial Infarction

“…Multiple detection platforms for cardiac enzymes are developed using a single chip with a mixture of independent CK-MB and cTnI, unlike previous complex detection platforms. [11][12][13] Multiple SERS response characteristics of CK-MB and cTnI (Figure 4C), depending on their concentrations within the clinically relevant range, were simultaneously determined for each unique non-interfering peak. Moreover, at this point, the relative concentrations were fixed at the cutoff levels of 5 ng mL −1 for CK-MB and 0.8 ng mL −1 for cTnI, [5] corresponding to the T1 value in the typical time course of CK-MB and cTnI elevations after the occurrence of an AMI event.…”

“…Acute myocardial infarction (AMI), associated with high mortality worldwide, is a type of myocardial necrosis caused by acute rapid AMI diagnosis. [7][8][9][10][11][12][13][14] Furthermore, the detection of these biomarkers can be used to trace the cause of death and disease stages in forensic science. [15][16][17] Most studies on fluorescencebased biomarker detection or electrochemical techniques have focused on improving AMI diagnosis accuracy and speed.…”

“…Recent SERS biosensing studies have focused on improving diagnostic accuracy through multiple detections of biomarkers instead of a single detection. [11,12,14] However, these studies showed multiple detection results through increased simultaneous detections by increasing the number of paths branched in a microfluidic platform. The quantification of various biomarkers and the design of uncomplicated platforms are critical factors in determining a rapid and precise AMI diagnosis.…”

Portable microfluidic plasmonic chip for fast real-time cardiac troponin I biomarker thermoplasmonic detection

“…23 To our knowledge, there were only a few microfluidic devices developed for cTnI SERS detection, for example the use of plasmonic nanostrip microcone arrays has shown promising results. 24 Additionally, AuNPs coupled with magnetic beads were successfully implemented as signal transducers for LSPR detection. 25 Furthermore, the first approaches to exploit the heat generated by gold nanoparticles for biomedical applications emerged in the early 2000s, 26,27 thus becoming the foundation of the rapidly growing and promising field called thermoplasmonics.…”

Electrochemical Sandwich-Type Aptasensor Based on the Multifunctional Catechol-Loaded Au/MIL-53(Fe) for Detection of Cardiac Troponin I

“…The clinical diagnosis for AMI is conducted using electrocardiography (ECG), coronary angiography, and assessment of biomarker levels. In contrast to the low accuracy of ECG, with 57% of patients diagnosed correctly, and utilizing the contrast agent in coronary angiography, which made this method invasive and time-consuming, the cTnI blood biomarker has been established as an extremely specific and sensitive measurement for a precise assessment of the progression of AMI disease. − As a result, a sensitive and simple method for detecting cTnI is extremely valuable for AMI patients’ early detection and critical treatment. − Nowadays, the primary method for detecting cTnI is based on the antigen–antibody interaction as an immunosensor − or DNA binding as an aptasensor. − Despite their high sensitivity and selectivity, immunosensors have several limitations, including low stability at high temperatures, a long period of the immune reaction, high antibody production costs, and the difficulty of chemically modifying antibodies for biological detection. − Target-binding aptamers with resistance to harsh conditions, ease of chemical synthesis, and high specific affinity for fast-capturing cTnI have been developed as alternatives to antibodies. , By using the systematic evolution of ligands by exponential enrichment (SELEX) technique, Ban and colleagues developed extremely sensitive and selective single-stranded DNA aptamers against cTnI . Studies revealed that compared to the anti-cTnI antibody, Tro4 and Tro6 aptamers exhibited superior binding abilities to cTnI, and their dissociation constants were lower than those of the anti-cTnI antibody .…”