Disposable screen-printed chemiluminescent biochips for the simultaneous determination of four point-of-care relevant proteins

Electrochemical and Plasmonic Detection of Myocardial Infarction Using Microfluidic Biochip Incorporated with Mesoporous Nanoscaffolds

This paper reports a microfluidic device for the electrochemical and plasmonic detection of cardiac myoglobin (cMb) and cardiac troponin I (cTnI) with noticeable limits of detection (LoD) as low as a few picograms per milliliter (pg/mL) ranges, achieved in a short detection time. The device features two working electrodes, each with a mesoporous Ni3V2O8 nanoscaffold grafted with reduced graphene oxide (rGO) that improves the interaction of diffusing analyte molecules with the sensing surface by providing a high surface area and reaction kinetics. Electrochemical studies reveal sensitivities as high as 9.68 μA ng/mL and a LoD of 2.0 pg/mL for cTnI, and 8.98 μA ng/mL and 4.7 pg/mL for cMb. Additionally, the surface plasmon resonance (SPR) studies demonstrate a low-level LoD of 8.8 pg/mL for cMb and 7.3 pg/mL for cTnI. The dual-modality sensor enables dynamic tracking of kinetic antigen-antibody interactions during sensing, self-verification through providing signals of two modes, and reduced false readout. This study demonstrates the complementary nature of the electrochemical and SPR modes in biosensing, with the electrochemical mode being highly sensitive and the SPR mode providing superior tracking of molecular recognition behaviors. The presented sensor represents a significant innovation in cardiovascular disease management and can be applied to monitor other clinically important biomolecules.

A multiplexed immunochemical microarray for the determination of cardiovascular disease biomarkers

A fluorescence antibody microarray has been developed for the determination of relevant cardiovascular disease biomarkers for the analysis of human plasma samples. Recording characteristic protein molecular fingerprints to assess individual's states of health could allow diagnosis to go beyond the simple identification of the disease, providing information on its stage or prognosis. Precisely, cardiovascular diseases (CVDs) are complex disorders which involve different degenerative processes encompassing a collection of biomarkers related to disease progression or stage. The novel approach that we propose is a fluorescent microarray chip has been developed accomplishing simultaneous determination of the most significant cardiac biomarkers in plasma aiming to determine the CVD status stage of the patient. As proof of concept, we have chosen five relevant biomarkers, C-reactive protein (CRP) as biomarker of inflammation, cystatin C (CysC) as biomarker of renal failure that is directly related with heart failure, cardiac troponin I (cTnI) as already established biomarker for cardiac damage, heart fatty acid binding protein as biomarker of ischemia (H-FABP), and finally, NT-proBNP (N-terminal pro-brain natriuretic peptide), a well-established heart failure biomarker. After the optimization of the multiplexed microarray, the assay allowed the simultaneous determination of 5 biomarkers in a buffer solution reaching LODs of 15 ± 5, 3 ± 1, 24 ± 3, 25 ± 3, and 3 ± 1 ng mL-1, for CRP, CysC, H-FABP, cTnI, and NT-proBNP, respectively. After solving the matrix effect, and demonstrating the accuracy for each biomarker, the chip was able to determine 24 samples per microarray chip. Then, the microarray has been used on a small pilot clinical study with 29 plasma samples from clinical patients which suffered different CVD and other related disorders. Results show the superior capability of the chip to provide clinical information related to the disease in terms of turnaround time (1 h 30 min total assay and measurement) and amount of information delivered in respect to reference technologies used in hospital laboratories (clinical analyzers). Despite the failure to detect c-TnI at the reported threshold, the microarray technology could be a powerful approach to diagnose the cardiovascular disease at early stage, monitor its progress, and eventually providing information about an eminent potential risk of suffering a myocardial infarction. The microarray chip here reported could be the starting point for achieving powerful multiplexed diagnostic technologies for the diagnosis of CVDs or any other pathology for which biomarkers have been identified at different stages of the disease.

Highly Sensitive, Portable Detection System for Multiplex Chemiluminescence Analysis

Chemiluminescence (CL) has emerged as a critical tool for the sensing and quantification of various bioanalytes in virtually all clinical fields. However, the rapid nature of many CL reactions raises challenges for typical low-cost optical sensors such as cameras to achieve accurate and sensitive detection. Meanwhile, classic sensors such as photomultiplier tubes are highly sensitive but lack spatial multiplexing capabilities and are generally not suited for point-of-care applications outside a standard laboratory setting. To address this issue, in this paper, a miniaturized and versatile silicon-photomultiplier-based fiber-integrated CL device (SFCD) was designed for sensitive multiplex CL detection. The SFCD comprises a silicon photomultiplier array coupled to an array of high numerical aperture plastic optical fibers to achieve 16-plex detection. The optical fibers ensure efficient light collection while allowing the fixed detector to be mated with diverse sample geometries (e.g., circular or grid), simply by adjusting the fiber configuration. In a head-to-head comparison with a lens-based camera system featuring a cooled detector, the SFCD achieved a 14-fold improved limit of detection in both direct and enzyme-mediated CL reactions. The SFCD also features improved compactness and lower cost, as well as faster temporal resolution compared with camera-based systems while preserving spatial multiplexing and good environmental robustness. Thus, the SFCD has excellent potential for point-of-care biosensing applications.

Direct fabrication of NbS2 nanoflakes on carbon fibers by atomic layer deposition for ultrasensitive cardiac troponin I detection

The sensitive detection of cardiac troponin I (cTnI) is of great significance for the early diagnosis of acute myocardial infarction (AMI). Herein, in order to fabricate an electrochemical biosensor for ultrasensitive cTnI detection, atomic layer deposition (ALD) was employed to directly deposit NbS₂ nanoflakes (NFs) on carbon fiber paper (CFP). Due to the self-limiting reaction of ALD, NbS₂NFs were deposited uniformly and accurately on the surface of carbon fibers by controlling the number of ALD cycles, which ensured ultrasensitive detection. Precise regulation of the nanoscale morphology and electrochemical performance of NbS₂ nanoflakes via ALD cycles was observed in depth. Owing to the high surface area and conductivity, an anodic/cathodic current of ∼3.01 mA of NbS₂NFs/CFP can be obtained. Subsequently, an electrochemical biosensor based on the excellent performance of NbS₂NFs/CFP was fabricated. The ultrasensitive detection of cTnI in a linear range of 1 fM to 0.1 nM with a detection limit of 0.32 fM was achieved.

Electrochemical strategies for the detection of cTnI

Acute myocardial infarction (AMI) is the main cause of death from cardiovascular diseases. Thus, early diagnosis of AMI is essential for the treatment of irreversible damage from myocardial infarction. Traditional electrocardiograms (ECG) cannot meet the specific detection of AMI. Cardiac troponin I (cTnI) is the main biomarker for the diagnosis of myocardial infarction, and the detection of cTnI content has become particularly important. In this review, we introduced and compared the advantages and disadvantages of various cTnI detection methods. We focused on the analysis and comparison of the main indicators and limitations of various cTnI biosensors, including the detection range, detection limit, specificity, repeatability, and stability. In particular, we pay more attention to the application and development of electrochemical biosensors in the diagnosis of cardiovascular diseases based on different biological components. The application of electrochemical microfluidic chips for cTnI was also briefly introduced in this review. Finally, this review also briefly discusses the unresolved challenges of electrochemical detection and the expectations for improvement in the detection of cTnI biosensing in the future.

Dual-modality microfluidic biosensor based on nanoengineered mesoporous graphene hydrogels

A dual-modality microfluidic biosensor is fabricated using a mesoporous nanostructured cysteine-graphene hydrogel for the quantification of human cardiac myoglobin (cMb). In this device, the nanoengineered mesoporous l-cysteine-graphene (Cys-RGO) hydrogel performs the role of a dual-modality sensing electrode for the measurements conducted using differential pulse voltammetry and surface plasmon resonance (SPR) techniques. High surface reactivity, mesoporous structure and fast electron transfer combined with good reaction kinetics of the graphene hydrogel in this device indicate excellent performance for the detection of human cardiac myoglobin in serum samples. In electrochemical modality, this microfluidic chip exhibits a high sensitivity of 196.66 μA ng^-1 mL cm^-2 for a linear range of concentrations (0.004-1000 ng mL^-1) with a low limit of detection (LOD) of 4 pg mL^-1 while the SPR technique shows a LOD of 10 pg mL^-1 for cMb monitoring in the range 0.01-1000 ng mL^-1. The intra-assay coefficient of variation was less than 8% for standard samples and 9% for real serum samples, respectively. This Cys-RGO hydrogel-based microfluidic SPR chip allows real-time dynamic tracking of cMb molecules with a high association constant of 4.93 ± 0.2 × 10⁵ M^-1 s^-1 and a dissociation constant of 1.37 ± 0.08 × 10^-4 s^-1, self-verification, reduced false readout, and improved detection reliability.

Grafting of Diazonium Salts on Surfaces: Application to Biosensors

This review is divided into two parts; the first one summarizes the main features of surface modification by diazonium salts with a focus on most recent advances, while the second part deals with diazonium-based biosensors including small molecules of biological interest, proteins, and nucleic acids.

A hollow-nanosphere-based microfluidic biosensor for biomonitoring of cardiac troponin I

Cardiovascular diseases (CVDs) are the leading causes of death worldwide.

Adding Biomolecular Recognition Capability to 3D Printed Objects

Three-dimensional (3D) printing technologies will impact the biosensor community in the near future, at both the sensor prototyping level and the sensing layer organization level. The present study aimed at demonstrating the capacity of one 3D printing technique, digital light processing (DLP), to produce hydrogel sensing layers with 3D shapes that are unattainable using conventional molding procedures. The first model of the sensing layer was composed of a sequential enzymatic reaction (glucose oxidase and peroxidase), which generated a chemiluminescent signal in the presence of glucose and luminol. Highly complex objects with assembly properties (fanciful ball, puzzle pieces, 3D pixels, propellers, fluidic and multicompartments) with mono-, di-, and tricomponents configurations were achieved, and the activity of the entrapped enzymes was demonstrated. The second model was a sandwich immunoassay protocol for the detection of brain natriuretic peptide. Here, highly complex propeller shape sensing layers were produced, and the recognition capability of the antibodies was elucidated. The present study opens then the path to a totally new field of development of multiplex sensing layers, printed separately and assembled on demand to create complex sensing systems.

Diagnostics on acute myocardial infarction: Cardiac troponin biomarkers

Acute myocardial infarction or myocardial infarction (MI) is a major health problem, due to diminished flow of blood to the heart, leads to higher rates of mortality and morbidity. Data from World Health Organization (WHO) accounted 30% of global death annually and expected more than 23 million die annually by 2030. This fatal effects trigger the need of appropriate biomarkers for early diagnosis, thus countermeasure can be taken. At the moment, the most specific markers for cardiac injury are cardiac troponin I (cTnI) and cardiac troponin T (cTnT) which have been considered as 'gold standard'. Due to higher specificity, determination of the level of cardiac troponins became a predominant indicator for MI. Several ways of diagnostics have been formulated, which include enzyme-linked immunosorbent assay, chemiluminescent, fluoro-immunoassays, electrical detections, surface plasmon resonance, and colorimetric protein assay. This review represents and elucidates the strategies, methods and detection levels involved in these diagnostics on cardiac superior biomarkers. The advancement, sensitivity, and limitations of each method are also discussed. In addition, it concludes with a discussion on the point-of care (POC) assay for a fast, accurate and ability of handling small sample measurement of cardiac biomarker.

Analytical chemiluminescence and bioluminescence: latest achievements and new horizons

Chemiluminescence (CL) and bioluminescence (BL) are the detection techniques of choice for the development of highly sensitive analytical methods, from immunoassays and nucleic acid hybridization assays to whole-cell biosensors. Nevertheless, basic and applied research on CL and BL aimed at further improving their analytical performance is still very active. This research covers diverse and complementary fields, including (among others) enhancing the light emission efficiency of CL systems, the use of nanomaterials to catalyze or enhance CL/BL reactions, the study of BL proteins to elucidate the color modulation mechanism, the discovery of new BL systems, the production of thermostable BL protein mutants with altered emission spectra, the development of BL imaging techniques to expand our understanding of living systems, and the implementation of CL/BL detection in miniaturized analytical devices. In the near future, we expect even greater diffusion of CL/BL-based analytical methods, especially in portable analytical devices intended for applications ranging from environmental analysis to companion diagnostics for personalized medicine.

Chemiluminescent enzyme immunoassays: a review of bioanalytical applications

This review gives an overview of the most recent and innovative developments in the field of chemiluminescent immunoassays through carefully selected examples. First, assays using microtiter plates for high-throughput or multiplexed assays aiming to achieve more complex assays through the multiplication of parameters per wells will be described. Systems will then be presented that have been recently developed, motivated by integration and miniaturization of existing immunoassays in more complex experimental setups. Finally, enhanced-performance chemiluminescent biochips, based on chemiluminescent reaction intensification, will be introduced.

Aldehyde-functionalized benzenediazonium cation for multiprobe immobilization on microelectrode array surfaces

We report in situ generation of aldehyde-functionalized benzenediazonium cation (ABD) and its use as a suitable linker molecule for fast and selective immobilization of biomolecules on indium-tin-oxide (ITO) electrode surfaces. We prepared ABD through a new reaction procedure, a simultaneous diazotation of the amine group and deprotection of the aldehyde group from an aniline derivative, 2-(4-aminophenyl)-1,3-dithiane, which was revealed on the ITO electrode surfaces through the electrodeposition of the reaction product and the characterization of the resulting surfaces with cyclic voltammetry, X-ray photoelectron spectroscopy, and protein immobilization. We also showed that successive electrodeposition of ABD and probe molecules on individually addressable microarray electrode surfaces can provide a useful platform for efficient detection of multianalyte. The usage of ABD has been demonstrated by the patterning of three different probe molecules on a single substrate and the simultaneous detection of two target molecules.

"Print-n-Shrink" technology for the rapid production of microfluidic chips and protein microarrays

An innovative method for the production of microfluidic chips integrating protein spots is described. The technology, called "Print-n-Shrink", is based on the screen-printing of a microfluidic design (using a dielectric ink) onto Polyshrink polystyrene sheets. The initial print which has a minimum size of 15 microm (height) x 230 microm (width) is thermally treated (30 seconds, 163 degrees C) to shrink and generate features of 85 microm (height) x 100 microm (width). Concomitantly, proteins such as monoclonal antibodies or cellular adhesion proteins are spotted onto the Polyshrink sheets and shrunk together with the microfluidic design, creating a complete biochip integrating both complex microfluidic designs and protein spots for bioanalytical applications.

Protein-diazonium adduct direct electrografting onto SPRi-biochip

A direct protein immobilization method for surface plasmon resonance imaging (SPRi) gold chip arraying is exposed. The biomolecule electroaddressing strategy, previously demonstrated by our team on carbon surfaces, is here valuably involved and adapted to create a straightforward and efficient protein immobilization process onto SPRi-biochips. The proteins, modified with an aryl-diazonium adduct, are addressed to the SPRi chip surface through the electroreduction of the aryl-diazonium. The biomolecule deposition was followed through SPRi live measurements during the electrografting process. A specially designed setup enabled us to directly observe the mass increasing at the sensor surface while the proteins were electrografted. A pin electrospotting method, allowing the achievement of distinct sensing layers on gold SPRi-biochips, was used to generate microarray biochips. The integrity of the immobilized proteins and the specificity of the detection, based on antigen/antibody interactions, were demonstrated for the detection of specific antibodies and ovalbumin. The SPRi detection limit of ovalbumin using the electroaddressing of anti-ovalbumin IgG was compared with two other immobilization procedures, cystamine-glutaraldehyde self-assembled monolayer and pyrrole, and was found to be a decade lower than these ones (100 ng/mL, i.e., 2 nM).