Aptamer-modified magnetic SERS substrate for label-based determination of cardiac troponin I

Magnetic-plasmonic nanoparticle-based surface-enhanced Raman scattering for biomedical detection

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that enables rapid, non-destructive, and susceptible detection of biological samples. The magnetic-plasmonic composite materials composed of magnetic and plasmonic nanoparticles have attracted extensive attention as SERS substrates in the biomedical field because of their ability to enrich, separate, and selectively identify biomolecules. In this review, the state-of-art progress of magnetic-plasmonic nanoparticle (MPNP)-based SERS substrates for biomedical detection is highlighted, covering the design and construction of MPNPs with different morphologies, organic and inorganic surface functionalization strategies adopted to improve the adaptability and applicability in biological systems for MPNPs, application development of MPNPs in biomedical detection, as well as the future challenges and issues to be addressed. It is highly expected that this review will help to fully understand the research status of MPNP-based SERS substrates and facilitate their further development and wider application in biological systems.

Magnetic-assisted and aptamer-based SERS biosensor for high enrichment, ultrasensitive detection of multicomponent heart failure biomarkers

The high-sensitivity detection of low-concentration multicomponent biomarkers in the blood of heart failure (HF) patients using surface-enhanced Raman spectroscopy (SERS) remains a significant challenge. In this study, an ultrasensitive biosensor for the detection of multicomponent HF biomarkers was designed. This biosensor utilizes Au@Ag nanoparticles (Au@Ag NPs) functionalized with Raman reporter molecules (RaRs) as SERS probes, and Ag-coated Fe3O4 nanoparticles (Fe3O4-Ag NPs) modified with internal standard (IS) molecules as the capture substrate, offering the dual advantages of magnetic enrichment and SERS enhancement. Additionally, specific aptamers or antibodies were conjugated to the surfaces of Au@Ag NPs and Fe3O4-Ag NPs to specifically recognize target proteins to construct a three-layer composite structure (Fe3O4-Ag/HF biomarkers/Au@Ag). The limit of detection (LOD) of HF markers for cTnI, NT-proBNP, and sST2 is 0.1 pg/mL, 1.0 fg/mL, and 1.0 fg/mL, respectively, surpassing most reported methods. Additionally, the analysis of 45 clinical serum samples revealed no statistically significant differences between the SERS-based results and those obtained by conventional clinical methods, as confirmed by the Shapiro-Wilk test (p > 0.05). In conclusion, this SERS biosensor successfully developed an easy-to-operate accurate diagnosis method capable of simultaneous, quantitative detection of multiple HF biomarkers and provided a new technique for accurate diagnosis of other diseases in clinical testing.

A novel and universal dual-channel signal amplification aptasensing platform for ultrasensitive and rapid detection of cardiac biomarkers based on the mutual regulation of bimetallic organic framework and silver nanoclusters

Cardiac troponin I (cTnI) is a key biomarker for diagnosing myocardial infarction caused by myocardial injury. The accurate and rapid monitoring of ultralow levels of cTnI is crucial for early diagnosis and risk warning of myocardial injury. Herein, a novel dual-channel signal amplification aptasensor for cTnI detection was developed utilizing the mutual regulation of bimetallic organic framework (MOFs) and silver nanoclusters (AgNCs) with the assistance of catalytic hairpin assembly (CHA). Rationally designed triple-helix molecular switch (THMS) and two hairpin probes (HP1 and HP2) containing AgNCs and a guanine-rich DNA sequence could be adsorbed onto the surface of bimetallic Cu, Mo-MOFs, enhancing the catalytic activity and reducing the fluorescence signal. The target cTnI specifically binds to the aptamer in the THMS, releasing the signal transduction probe which triggers CHA to desorb HP1-AgNCs and HP2, thereby restoring the fluorescence and decreasing the catalytic activity as well as initiating cycling. This enables dual-channel fluorescence and colorimetric detection of cTnI. The linear fluorescence and colorimetric response ranges were 0.001-20 ng/mL with LOD of 0.48 pg/mL and 0.001-10 ng/mL with LOD of 0.69 pg/mL, respectively. The aptasensor significantly increases the detection sensitivity and reduces the time required for cTnI detection in human serum, with excellent anti-interference capability. Moreover, the aptasensor shows promise for the construction of universal dual-channel aptasensors for multiple targets by altering the aptamer in THMS.

A novel fluorometric and colorimetric dual-mode sensor for AMI early diagnosis based on an ultrathin Fe-MOF-74 nanosheet with peroxidase mimic activity and fluorescence properties

BACKGROUND

Cardiac troponin I (cTnI) is a crucial diagnosis biomarker for acute myocardial infarction (AMI). Early accurate determination of the concentration of cTnI significantly decreases the death rate of AMI. Compared with classic methods, dual-mode sensors for cTnI determination could help reduce the false positive rate.

RESULT

In this work, an ultrathin Fe-MOF-74 nanosheet with fluorescence properties and peroxidase mimic activity was synthesized for the first time. Applying this nanosheet, a novel dual-mode sensor was developed to quantify cTnI in human serum. The ultrathin Fe-MOF-74 nanosheets catalyze the decomposition of hydrogen peroxide produced by glucose oxidase (GOx)-triggered enzyme-linked immunosorbent assay (ELISA) applying cTnI as an antigen target, to generate reactive oxygen species (ROS). 3,3',5,5'-tetramethylbenzidine (TMB) can be oxidized by the generated free radicals, which simultaneously lead to the fluorescence quench of Fe-MOF-74 due to the inner filter effect (IFE). The correlation between the morphology of Fe-MOF-74 and its fluorescence intensity and peroxidase mimic activity was also investigated.

SIGNIFICANCE

The sensors exhibited linearity with the concentration of cTnI in 10-2000 pg mL-1 in both the fluorescence and visual mode with the detection limit of 6.4 pg mL-1 and 8.4 pg mL-1, respectively. It presenting good selectivity and anti-interference ability, can provide accurate and precise results in testing the concentration of cTnI in serum samples from patients in hospitals. It could be applied in the early diagnosis of AMI to reduce the incidence, disability, and mortality rates.

Aptasensor-based point-of-care detection of cardiac troponin biomarkers for diagnosis of acute myocardial infarction

Acute myocardial infarction (AMI) represents a critical health challenge characterized by a significant reduction in blood flow to the heart, leading to high rates of mortality and morbidity. Cardiac troponins, specifically cardiac troponin I and cardiac troponin T, are essential proteins involved in cardiac muscle contraction and serve as vital biomarkers for the diagnosis of AMI. Aptasensors utilize synthetic aptamers or peptides with high affinity for specific biomarkers and offer a promising approach for integration into portable, user-friendly point-of-care (POC) applications. This review explores recent advances in POC aptasensor-based platforms for the rapid detection of cardiac troponin biomarkers. Furthermore, this review addresses current challenges and potential future directions in the development of aptasensor. Also, it highlights their potential to improve timely and accurate diagnosis in clinical and emergency settings.

Recent development of gold nanochips in biosensing and biodiagnosis sensibilization strategies in vitro based on SPR, SERS and FRET optical properties

Gold nanomaterials have become attractive nanomaterials for biomedical research due to their unique physical and chemical properties, and nanochips are designed to manufacture high-quality substrates for loading gold nanoparticles (GNPs) to achieve specific and selective detection. By utilizing multiple optical properties of different gold nanostructures, the sensitivity, specificity, speed, contrast, resolution, and other performance of biosensing and biological diagnosis can be significantly improved. This paper summarized the sensitivity enhancement strategies of optical biosensing techniques based on the three main optical properties of gold nanomaterials: surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS) and fluorescence resonance energy transfer (FRET). The aim is to comprehensively review the development direction of in vitro diagnostics (IVDs) from two aspects: detection strategies and modification of gold nanomaterials. In addition, some opportunities and challenges that gold-based IVDs may encounter at present or in the future are also mentioned in this paper. In summary, this paper can enlighten readers with feasible strategies for manufacturing potential gold-based nanobiosensors.

Ratiometric surface-enhanced Raman spectroscopy detection of 5-hydroxyindole-3-acetic acid based on Au@MIL-125@MIPs substrates

5-Hydroxyindole-3-acetic acid (5-HIAA) is a molecular marker that can be used in the early diagnosis of carcinoid tumors, and the development of sophisticated 5-HIAA assays is therefore of great importance. Surface-enhanced Raman spectroscopy (SERS) has been widely used for the rapid and sensitive detection of disease biomarkers. Insufficient specificity for tumor markers and poor spectral reproducibility are the bottlenecks in the practical use of SERS technology. In this study, based on MIL-125 surface-loaded gold nanoparticles (Au@MIL-125), a novel strategy was proposed to obtain Au@MIL-125@molecularly imprinted polymers (MIPs) as functional SERS substrates by wrapping a thin MIP shell around the Au@MIL-125 surface for selective separation followed by a 5-HIAA assay. The Raman peak intensity ratio (I865/I1078) was used to quantify 5-HIAA after a SERS spectral calibration with an embedded internal standard (i.e., 4-aminobenzenethiol) to improve the quantitative accuracy. The linear range was from 10-11 to 10-7 M, and the limit of detection (LOD) was 5.45 × 10-13 M. The method of integrating the MIPs with the metal MOF-based nanocomposites was shown to be useful in the analysis of real samples using SERS. The application of SERS for the selective and quantitative detection of analytes in real sample analysis, therefore, has great potential.

A magnetic SERS-imprinted sensor for the determination of cardiac troponin I based on proteolytic peptide technology

Acute myocardial infarction is a sudden and high-mortality disease that can be accurately diagnosed by measuring the level of cardiac troponin I in the blood. Currently, cTnI commonly used clinical detection methods usually have excellent sensitivity and are suitable for large-scale sample detection analysis. However, most of these methods are operated through multiple steps of fixation, incubation, reaction and separation, and most of them require professionals to operate complex instruments, which greatly limits their applicability in real-time rapid detection. Therefore, a method that requires low professional skills and can perform rapid detection is necessary. We presents an alternative strategy to quantify cTnI in clinical serum samples using a combination of SERS and magnetic molecularly imprinted polymers (MMIP). MMIPs was synthesized under Polyvinyl Pyrrolidone (PVP) conditions without vinyl modification using characteristic peptide as template, MAA and DMAm as functional monomers. The internal Raman probe 4-MBA was connected through Ag-SH bonds in MMIPs to solve the problem that the target object had no Raman characteristic peak. MMIPs with high magnetic and adsorptive properties showed characteristic absorption peaks at the Raman shift of 1582 cm-1 after specific capture of the target templates. The Raman signals of the 4-MBA were reduced due to shielding effects and the detection range of this method was 0.001-100 ng mL-1. The recoveries and relative standard deviations (RSDs) of the spiked experiments were 103.1%-106.3 % and 3.54 %-7.38 %, respectively. In summary, this work had appropriate sensitivity and specificity, and there was no significant difference in detection results after ELISA verification. It provided a flexible and practical analysis method for detecting cTnI based on SERS technology. In addition, the imprinting materials of other disease markers can be prepared by changing the template molecules, which provides a new idea for the detection of other biomarkers.

A novel highly active AgMOF-based silver single-atom catalyst and its application to the aptamer SERS/RRS for the determination of aflatoxin B1

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl4-H2Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (AptAFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to AptAFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005-0.225 μg/L and a detection limit of 0.002 μg/L.

Hybridization chain reaction-enhanced electrochemically mediated ATRP coupling high-efficient magnetic separation for electrochemical aptasensing of cardiac troponin I

The sensitive and accurate detection of cardiac troponin I (cTnI) as a gold biomarker for cardiovascular diseases at an early stage is crucial but has long been a challenge. In this study, we presented such an electrochemical (EC) aptasensor by combining hybridization chain reaction (HCR)-enhanced electrochemically mediated atom transfer radical polymerization (eATRP) amplification with high-efficient separation of magnetic beads (MBs). Aptamer-modified MBs empowered effective recognition and separation of cTnI from complex samples with high specificity. The specific binding of cTnI and aptamer could release triggered DNA (T-DNA) into solution to drive an HCR process, which produced plentiful active sites for eATRP initiators labeling followed by initiating eATRP process. With the development of eATRP, a great many of electroactive polymer probes were continually in situ formed to generate amplified current output for signal enhancement. Compared to no amplification, HCR-enhanced eATRP promoted the signals by ∼10-fold, greatly improving detection sensitivity for low-abundant cTnI analysis. Integrating MBs as capture carriers with HCR-enhanced eATRP as amplification strategy, this EC aptasensor achieved a low detection limit of 10.9 fg/mL for cTnI detection. Furthermore, the reliable detectability and anti-interference were confirmed in serum samples, indicating its promising application toward early diagnosis of cardiovascular diseases.

Aptamer-Magnetic Nanoparticle Complexes for Powerful Biosensing: A Comprehensive Review

The selective and sensitive diagnosis of diseases is a significant matter in the early stages of the cure of illnesses. To elaborate, although several types of probes have been broadly applied in clinics, magnetic nanomaterials-aptamers, as new-generation probes, are becoming more and more attractive. The presence of magnetic nanomaterials brings about quantification, purification, and quantitative analysis of biomedical, especially in complex samples. Elaborately, the superparamagnetic properties and numerous functionalized groups of magnetic nanomaterials are considered two main matters for providing separation ability and immobilization substrate, respectively. In addition, the selectivity and stability of aptamer can present a high potential recognition element. Importantly, the integration of aptamer and magnetic nanomaterials benefits can boost the performance of biosensors for biomedical analysis by introducing efficient and compact probes that need low patient samples and fast diagnosis, user-friendly application, and high repeatability in the quantification of biomolecules. The primary aim of this review is to suggest a summary of the effect of the employed other types of nanomaterials in the fabrication of novel aptasensors-based magnetic nanomaterials and to carefully explore various applications of these probes in the quantification of bioagents. Furthermore, the application of these versatile and high-potential probes in terms of the detection of cancer cells and biomarkers, proteins, drugs, bacteria, and nucleoside were discussed. Besides, research gaps and restrictions in the field of biomedical analysis by magnetic nanomaterials-aptamers will be discussed.

Nucleic Acid Aptamer-Based Biosensors: A Review

Aptamers, short strands of either DNA, RNA, or peptides, known for their exceptional specificity and high binding affinity to target molecules, are providing significant advancements in the field of health. When seamlessly integrated into biosensor platforms, aptamers give rise to aptasensors, unlocking a new dimension in point-of-care diagnostics with rapid response times and remarkable versatility. As such, this review aims to present an overview of the distinct advantages conferred by aptamers over traditional antibodies as the molecular recognition element in biosensors. Additionally, it delves into the realm of specific aptamers made for the detection of biomarkers associated with infectious diseases, cancer, cardiovascular diseases, and metabolomic and neurological disorders. The review further elucidates the varying binding assays and transducer techniques that support the development of aptasensors. Ultimately, this review discusses the current state of point-of-care diagnostics facilitated by aptasensors and underscores the immense potential of these technologies in advancing the landscape of healthcare delivery.

Exploring the Clinical Utility of Raman Spectroscopy for Point-of-Care Cardiovascular Disease Biomarker Detection

A variety of innovative point-of-care (POC) solutions using Raman systems have been explored. However, the vast effort is in assay development, while studies of the characteristics required for Raman spectrometers to function in POC applications are lacking. In this study, we tested and compared the performance of eight commercial Raman spectrometers ranging in size from benchtop Raman microscopes to portable and handheld Raman spectrometers using paper fluidic cartridges, including their ability to detect cardiac troponin I and heart fatty acid binding protein, both of which are well-established biomarkers for evaluating cardiovascular health. Each spectrometer was evaluated in terms of excitation wavelength, laser characteristics, and ease of use to investigate POC utility. We found that the Raman spectrometers equipped with 780 and 785 nm laser sources exhibited a reduced background signal and provided higher sensitivity compared to those with 633 and 638 nm laser sources. Furthermore, the spectrometer equipped with the single acquisition line readout functionality showed improved performance when compared to the point scan spectrometers and allowed measurements to be made faster and easier. The portable and handheld spectrometers also showed similar detection sensitivity to the gold standard instrument. Lastly, we reduced the laser power for the spectrometer with single acquisition line readout capability to explore the system performance at a laser power that change the classification from a Class 3B laser device to a Class 3R device and found that it showed comparable performance. Overall, these findings show that portable Raman spectrometers have the potential to be used in POC settings with accuracy comparable to laboratory-grade instruments, are relatively low-cost, provide fast signal readout, are easy to use, and can facilitate access for underserved communities.

A Review of Magnetic Nanoparticle-Based Surface-Enhanced Raman Scattering Substrates for Bioanalysis: Morphology, Function and Detection Application

Surface-enhanced Raman scattering (SERS) is a kind of popular non-destructive and water-free interference analytical technology with fast response, excellent sensitivity and specificity to trace biotargets in biological samples. Recently, many researches have focused on the preparation of various magnetic nanoparticle-based SERS substrates for developing efficient bioanalytical methods, which greatly improved the selectivity and accuracy of the proposed SERS bioassays. There has been a rapid increase in the number of reports about magnetic SERS substrates in the past decade, and the number of related papers and citations have exceeded 500 and 2000, respectively. Moreover, most of the papers published since 2009 have been dedicated to analytical applications. In the paper, the recent advances in magnetic nanoparticle-based SERS substrates for bioanalysis were reviewed in detail based on their various morphologies, such as magnetic core-shell nanoparticles, magnetic core-satellite nanoparticles and non-spherical magnetic nanoparticles and their different functions, such as separation and enrichment, recognition and SERS tags. Moreover, the typical application progress on magnetic nanoparticle-based SERS substrates for bioanalysis of amino acids and protein, DNA and RNA sequences, cancer cells and related tumor biomarkers, etc., was summarized and introduced. Finally, the future trends and prospective for SERS bioanalysis by magnetic nanoparticle-based substrates were proposed based on the systematical study of typical and latest references. It is expected that this review would provide useful information and clues for the researchers with interest in SERS bioanalysis.

A review of cardiac troponin I detection by surface enhanced Raman spectroscopy: Under the spotlight of point-of-care testing

Cardiac troponin I (cTnI) is a biomarker widely related to acute myocardial infarction (AMI), one of the leading causes of death around the world. Point-of-care testing (POCT) of cTnI not only demands a short turnaround time for its detection but the highest accuracy levels to set expeditious and adequate clinical decisions. The analytical technique Surface-enhanced Raman spectroscopy (SERS) possesses several properties that tailor to the POCT format, such as its flexibility to couple with rapid assay platforms like microfluidics and paper-based immunoassays. Here, we analyze the strategies used for the detection of cTnI by SERS considering POCT requirements. From the detection ranges reported in the reviewed literature, we suggest the diseases other than AMI that could be diagnosed with this technique. For this, a section with information about cardiac and non-cardiac diseases with cTnI release, including their release kinetics or cut-off values are presented. Likewise, POCT features, the use of SERS as a POCT technique, and the biochemistry of cTnI are discussed. The information provided in this review allowed the identification of strengths and lacks of the available SERS-based point-of-care tests for cTnI and the disclosing of requirements for future assays design.

A novel Apt-SERS platform for the determination of cardiac troponin I based on coral-like silver-modified magnetic substrate and BCA method

As a kind of acute cardiovascular disease, acute myocardial infarction (AMI) endangers human's life and fitness seriously. The detection of cardiac troponin I (cTnI), a biomarker of AMI, is the key to early medical prognosis and treatment. Surface-enhanced Raman spectroscopy is viewed to be an effective approach for detection of low-concentration substances, and aptamers are regarded to be effective fragments to recognize proteins specifically. In this work, a magnetic nanoparticle substrate coated with coral-like nano-silver was prepared, and the aptamer-modified substrate Fe₃O₄@PEI/Ag NC-Apt was used as magnetic capture probe. Combined with BCA method and SERS detection technology, an Apt-SERS platform was successfully constructed and used for high sensitivity quantitative detection of protein. Taking cTnI as the target, the detection range of the proposed Apt-SERS platform was 0.001-100 ng mL^-1, and the estimated detection of limit (LOD) was 0.23 pg mL^-1. The recovery and relative standard deviations (RSD) of spiked experiment in human serum samples were 92-106% and 3.8-10.1%, respectively. The platform combining BCA method and SERS provides a high sensitivity and good reproducibility method for cTnI detection, which offers a new method for the specific detection and analysis of proteins.

Aptamers Targeting Cardiac Biomarkers as an Analytical Tool for the Diagnostics of Cardiovascular Diseases: A Review

The detection of cardiac biomarkers is used for diagnostics, prognostics, and the risk assessment of cardiovascular diseases. The analysis of cardiac biomarkers is routinely performed with high-sensitivity immunological assays. Aptamers offer an attractive alternative to antibodies for analytical applications but, to date, are not widely practically implemented in diagnostics and medicinal research. This review summarizes the information on the most common cardiac biomarkers and the current state of aptamer research regarding these biomarkers. Aptamers as an analytical tool are well established for troponin I, troponin T, myoglobin, and C-reactive protein. For the rest of the considered cardiac biomarkers, the isolation of novel aptamers or more detailed characterization of the known aptamers are required. More attention should be addressed to the development of dual-aptamer sandwich detection assays and to the studies of aptamer sensing in alternative biological fluids. The universalization of aptamer-based biomarker detection platforms and the integration of aptamer-based sensing to clinical studies are demanded for the practical implementation of aptamers to routine diagnostics. Nevertheless, the wide usage of aptamers for the diagnostics of cardiovascular diseases is promising for the future, with respect to both point-of-care and laboratory testing.