Novel, Highly Sensitive, and Specific Assay to Monitor Acute Myocardial Infarction (AMI) by the Determination of Cardiac Troponin I (cTnI) and Heart-Type Fatty Acid Binding Protein (H-FABP) by a Colloidal Gold-Based Immunochromatographic Test Strip

Quantitative and rapid lateral flow immunoassay for cardiac troponin I using dendritic mesoporous silica nanoparticles and gold nanoparticles

Acute myocardial infarction (AMI) is considered to be one of the predominant causes of human death; therefore, a rapid and accurate diagnostic method for AMI is urgently required. In this work, a highly sensitive lateral flow immunoassay (LFIA) platform was designed and fabricated for the quantitative determination of cardiac troponin I (cTnI) using a scanner, a smartphone and a colloidal gold immunoassay analyzer. To overcome the limitation of low sensitivity of traditional colloidal gold-based LFIA, three-dimensionally assembled gold nanoparticles (AuNPs) within a dendritic mesoporous silica nanoparticle (DMSN) scaffold were fabricated as signal labels. The assembly structure greatly enhanced the light extinction ability of a single label for signal amplification. The DMSNs@Au-based LFIA strips exhibited excellent detection performance including a high sensitivity (LOD = 70 pg mL-1) and wide linear range (0.5-40 ng mL-1) and precision with good specificity. The successful determination of cTnI by the test strips provides the ability to diagnose AMI at an early stage and expands the diagnostic window of AMI, while also having advantages such as low cost and user-friendliness. Therefore, we believe that the test strips fabricated in this work have great potential to be applied for practical clinical applications for the early and accurate diagnosis of AMI.

Simultaneous detection method for two cardiac disease protein biomarkers on a single chip modified with mixed aptamers using surface plasmon resonance

A simultaneous detection method for two cardiac disease protein biomarkers present in serum samples on a single planar gold chip using surface plasmon resonance (SPR) is described. The detection of N-terminal pro-brain natriuretic peptide (NT-proBNP) and tumor necrosis factor α (TNF-α), which are known as acute myocardial infarction (AMI) biomarkers, with predetermined clinically relevant concentrations was performed using mixed aptamers specific to each protein tethered on a single gold surface. After the binding of NT-proBNP and/or TNF-α to the mixed aptamers, an antibody specific to each target protein was injected to form a surface sandwich complex to improve selectivity. In order to adjust the dynamic ranges in the known clinically relevant concentration significantly different for NT-proBNP (0.13-0.24 nM) and TNF-α (0.5-3 pM), the surface density ratios of the corresponding pair of aptamer and antibody were first systematically determined, which were the 1:1 mixed aptamer chip with 40 nM anti-NT-proBNP and 100 nM anti-TNF-α. This allowed to establish the distinct dynamic ranges of 0.05-0.5 nM for NT-proBNP and 0.1-5 pM for TNF-α in a buffer, along with detection and quantification limits of 0.03 and 0.19 nM for NT-proBNP and 0.06 and 0.21 pM for TNF-α, respectively. The changes in refractive unit (RU) values observed when exposing both proteins at different concentrations alongside the corresponding fixed concentration of antibodies onto the 1:1 mixed aptamer chip were then correlated to the sum of RU values measured when using the injection of individual protein for evaluating each protein concentration. With a complete characterization of the simultaneous quantification of two protein concentrations in the buffer, the mixed aptamer chip was finally employed for direct measurements of NT-proBNP and TNF-α concentrations in undiluted serum samples from healthy controls and AMI patients. The results of simultaneous SPR measurements for the two proteins in the serum samples were further compared to the individual protein concentration results using an enzyme-linked immunosorbent assay.

Nanotechnology for cardiovascular diseases

Cardiovascular diseases have become the major killers in today's world, among which coronary artery diseases (CADs) make the greatest contributions to morbidity and mortality. Although state-of-the-art technologies have increased our knowledge of the cardiovascular system, the current diagnosis and treatment modalities for CADs still have limitations. As an emerging cross-disciplinary approach, nanotechnology has shown great potential for clinical use. In this review, recent advances in nanotechnology in the diagnosis of CADs will first be elucidated. Both the sensitivity and specificity of biosensors for biomarker detection and molecular imaging strategies, such as magnetic resonance imaging, optical imaging, nuclear scintigraphy, and multimodal imaging strategies, have been greatly increased with the assistance of nanomaterials. Second, various nanomaterials, such as liposomes, polymers (PLGA), inorganic nanoparticles (AuNPs, MnO2, etc.), natural nanoparticles (HDL, HA), and biomimetic nanoparticles (cell-membrane coating) will be discussed as engineered as drug (chemicals, proteins, peptides, and nucleic acids) carriers targeting pathological sites based on their optimal physicochemical properties and surface modification potential. Finally, some of these nanomaterials themselves are regarded as pharmaceuticals for the treatment of atherosclerosis because of their intrinsic antioxidative/anti-inflammatory and photoelectric/photothermal characteristics in a complex plaque microenvironment. In summary, novel nanotechnology-based research in the process of clinical transformation could continue to expand the horizon of nanoscale technologies in the diagnosis and therapy of CADs in the foreseeable future.

Rapid and simultaneous detection of heart-type fatty acid binding protein and cardiac troponin using a lateral flow assay based on metal organic framework@CdTe nanoparticles

Herein, a zirconium metal organic framework (ZrMOF) based lateral flow assay (LFA) is described for the qualitative analysis of early acute myocardial infarction (AMI) biomarkers including heart-type fatty acid binding protein (h-FABP) and cardiac troponin (cTnT). ZrMOF@CdTe nanoparticles (NPs) are synthesized by a simple hydrothermal method. By changing the hydrothermal reaction time, ZrMOF@CdTe NPs with different fluorescent colours can be obtained. They can emit different colours of fluorescence under the excitation of a single wavelength, which makes them suitable for multiplexed lateral flow assays (mLFA). The visual limit of detection of the ZrMOF@CdTe-based LFA for the h-FABP antigen is 1 μg L-1. The analysis can be completed within 8 min and has the advantages of being easy to operate and visual detection. A serum sample collected from patients is successfully detected using this LFA. This assay is widely applicable and simple, has strong anti-interference ability, and is cost-effective and can provide basic information for later treatment.