Detection of the inflammation biomarker C-reactive protein in serum samples: towards an optimal biosensor formula

Development of a C-reactive protein quantification method based on flow rate measurement of an ink solution pushed out by oxygen gas generated by catalase reaction

A novel determination method for protein biomarkers based on on-chip flow rate measurement was developed using a microchip with organic photodiodes (OPDs). This quantitative method is based on the flow rate measurement of an ink solution pushed out by oxygen gas generated through catalase reaction. The amount of oxygen gas generated in the sample reservoir is dependent on the concentration of the analyte; therefore, the flow rate of the ink solution is also dependent on the concentration of the analyte. The concentration of the analyte can thus be estimated by measurement of the ink solution flow rate. The ink solution flow rate was estimated by measuring the migration time of the ink solution between two points using two OPDs placed below the microchannel. The principle of this method was demonstrated by the measurement of catalase using the microchip. In addition, the developed method was applied to the determination of C-reactive protein (CRP), a biomarker of inflammation, based on a catalase-linked immunosorbent assay (C-LISA). The limit of detection for CRP was 0.20 µg/mL. The method was also applied to the determination of CRP in human serum, and the quantitative values obtained by this method were in excellent agreement with those obtained by the conventional enzyme-linked immunosorbent assay (ELISA) method. The developed method does not require a photodetector with high sensitivity and is thus capable of downsizing; therefore, this will be useful for on-site analyses such as point-of-care testing and field measurements.

Electrochemical Biosensors for Whole Blood Analysis: Recent Progress, Challenges, and Future Perspectives

Whole blood, as one of the most significant biological fluids, provides critical information for health management and disease monitoring. Over the past 10 years, advances in nanotechnology, microfluidics, and biomarker research have spurred the development of powerful miniaturized diagnostic systems for whole blood testing toward the goal of disease monitoring and treatment. Among the techniques employed for whole-blood diagnostics, electrochemical biosensors, as known to be rapid, sensitive, capable of miniaturization, reagentless and washing free, become a class of emerging technology to achieve the target detection specifically and directly in complex media, e.g., whole blood or even in the living body. Here we are aiming to provide a comprehensive review to summarize advances over the past decade in the development of electrochemical sensors for whole blood analysis. Further, we address the remaining challenges and opportunities to integrate electrochemical sensing platforms.

Self-assembly strategy to reduce non-specific adsorption for the development of high sensitivity quantitative immunoassay

The development of functionalized surfaces with low non-specific adsorption is important for their biomedical applications. To inhibit non-specific adsorption on glass substrate, we designed a novel optical biochip by modifying a layer of dense negatively charged film (SO₃^2-) on its substrate surface via self-assembly. Compared with the untreated glass substrate, it reduced the adsorption by about 300-fold or 400-fold by poly (styrene sulfonic acid) sodium salt (PSS), or meso-tetra (4-sulfonatophenyl) porphine dihydrochloride (TSPP) on individually the modified glass substrate. Considering the effect of fluorescence resonance energy transfer (FRET) between TSPP and the QDs in solution by mixing, a strategy of 2-layer of TSPP followed by 4-layer of PSS was designed to modify the glass for preparing biochips. Under the optimized conditions, the biochip on functionalized glass substrate co-treated with TSPP and PSS realized the sensitive quantitative detection of C-reactive protein (CRP) based on a quantum dot fluorescence immunosorbent assay (QD-FLISA). The limit of detection (LOD) for CRP achieved 0.69 ng/mL with the range of 1-1,000 ng/mL using TSPP and PSS co-treated glass substrate surface, which was respectively about 1.9-fold and 7.5-fold more sensitive to the PSS-modified biochip and the TSPP-modified biochip. This work demonstrated an effective and convenient strategy to obtain biochips with low non-specific adsorption properties on functionalized surfaces, thus providing a new approach for creating ultra-high sensitivity microchannels or microarrays on glass substrates.

Electrochemical biosensor with electrokinetics-assisted molecular trapping for enhancing C-reactive protein detection

C-Reactive protein (CRP) is an essential biomarker relevant to various disease prognoses. Current biosensors require a significant amount of time for detecting CRP. To address this issue, this work proposes electrokinetic flow-assisted molecule trapping integrated with an impedance biosensor, where a driving signal in terms of a gated sine wave is provided to circularly arranged electrodes which detect proteins. To verify the biosensor's efficacy, protein aggregation on the electrode surface was evaluated through a fluorescence analysis and measurement of the electrochemical impedance spectrum (EIS). The fluorescence analysis with avidin showed that target samples largely accumulated on the electrode surface upon provision of the driving signal. The EIS measurement of CRP accumulation on the electrode surface further confirmed a significant electrokinetic phenomenon at the electrode/electrolyte interface. Even at the low CRP concentration of 10 pg/ml, the proposed device's sensitivity and reliability were as high as 3.92 pg/ml with a signal-to noise ratio (SNR) of ≥3, respectively. In addition, the protein detection time (without considering the preparation time) was minimized to as low as 90 s with the proposed device. This device's advantage is its minimal time consumption, and simple drop-analysis process flow; hence, it was used for monitoring clinical serum samples.

Reliability of C-reactive Protein as a Biomarker for Cardiovascular and Oral Diseases in Young and Old Subjects

BACKGROUND

Increased C-reactive protein (CRP) levels are associated with various diseases such as cardiovascular diseases (CVDs), periodontal diseases, and other inflammatory diseases and can be an effective biomarker for predicting future risks of periodontal diseases.

AIMS

The present trial was carried out to evaluate if CRP levels are lower in healthy and young individuals as compared to individuals with high body mass index (BMI), gingival index, and CVDs by assessing CRP levels in young and old individuals (more than 45 years).

MATERIALS AND METHODS

A total of 174 participants were recruited for the study and were divided into three following groups: Less than 45 years healthy participants (n = 124), more than 45 years healthy participants, and more 45-year-old participants with CVDs (n = 25). The collected data were subjected to the statistical analysis.

RESULTS

In Group I, females had a CRP level of 8476 ± 6.86 pg, females of Group II had a CRP value of 13,262 ± 3.76, and in females of Group III CRP value was 22,761 ± 6.24 pg. These values, respectively, for males were 8494 ± 7.68, 13,840 ± 4.82, and 13,839 ± 3.8. In smokers, the CRP values for Group I, II, and III were 29,012 ± 14.66, 12,568 ± 4.16, and 16,826 ± 3.42, respectively.

CONCLUSION

CRP levels were higher in males as compared to females. Higher BMI was associated with higher values of CRP. The participants with higher BMI presented higher CRP values irrespective of age.

The Challenges of Developing Biosensors for Clinical Assessment: A Review

Emerging research in biosensors has attracted much attention worldwide, particularly in response to the recent pandemic outbreak of coronavirus disease 2019 (COVID-19). Nevertheless, initiating research in biosensing applied to the diagnosis of diseases is still challenging for researchers, be it in the preferences of biosensor platforms, selection of biomarkers, detection strategies, or other aspects (e.g., cutoff values) to fulfill the clinical purpose. There are two sides to the development of a diagnostic tool: the biosensor development side and the clinical side. From the development side, the research engineers seek the typical characteristics of a biosensor: sensitivity, selectivity, linearity, stability, and reproducibility. On the other side are the physicians that expect a diagnostic tool that provides fast acquisition of patient information to obtain an early diagnosis or an efficient patient stratification, which consequently allows for making assertive and efficient clinical decisions. The development of diagnostic devices always involves assay developer researchers working as pivots to bridge both sides whose role is to find detection strategies suitable to the clinical needs by understanding (1) the intended use of the technology and its basic principle and (2) the preferable type of test: qualitative or quantitative, sample matrix challenges, biomarker(s) threshold (cutoff value), and if the system requires a mono- or multiplex assay format. This review highlights the challenges for the development of biosensors for clinical assessment and its broad application in multidisciplinary fields. This review paper highlights the following biosensor technologies: magnetoresistive (MR)-based, transistor-based, quartz crystal microbalance (QCM), and optical-based biosensors. Its working mechanisms are discussed with their pros and cons. The article also gives an overview of the most critical parameters that are optimized by developing a diagnostic tool.

Biosensors Designed for Clinical Applications

Emerging and validated biomarkers promise to revolutionize clinical practice, shifting the emphasis away from the management of chronic disease towards prevention, early diagnosis and early intervention. The challenge of detecting these low abundance protein and nucleic acid biomarkers within the clinical context demands the development of highly sensitive, even single molecule, assays that are also capable of selectively measuring a small number of defined analytes in complex samples such as whole blood, interstitial fluid, saliva or urine. Success relies on significant innovations in nanomaterials, bioreceptor engineering, transduction strategies and microfluidics. Primarily using examples from our work, this article discusses some recent advance in the selective and sensitive detection of disease biomarkers, highlights key innovations in sensor materials and identifies issues and challenges that need to be carefully considered especially for researchers entering the field.

Oriented Antibody Covalent Immobilization for Label-Free Impedimetric Detection of C-Reactive Protein via Direct and Sandwich Immunoassays

The detection and monitoring of biological markers as disease indicators in a simple manner is a subject of international interest. In this work, we report two simple and sensitive label-free impedimetric immunoassays for the detection of C-reactive protein (CRP). The gold electrode modified with boronic acid-terminated self-assembled monolayers afforded oriented immobilization of capture glycosylated antibody (antihuman CRP monoclonal antibody, mAb). This antibody-modified surface was able to capture human CRP protein, and the impedance signal showed linear dependence with CRP concentration. We confirmed the immobilization of anti-CRP mAb using surface sensitive X-ray photoelectron spectroscopy (XPS) and electrochemical impedance. The oriented covalent immobilization of mAb was achieved using glycosylated Fc (fragment, crystallizable) region specific to boronic acid. The direct immunoassay exhibited a linear curve for concentration range up to 100 ng ml^-1. The limit of detection (LoD) of 2.9 ng ml^-1, limit of quantification (LoQ) of 9.66 ng ml^-1, and sensitivity of 0.585 kΩ ng^-1 ml cm^-2 were obtained. The sandwich immunoassay was carried out by capturing polyclonal anti-CRP antibody (pAb) onto the CRP antigen immunoreaction. The impedance signal after pAb capture also showed linear dependence with CRP antigen concentration and acted as a CRP antigen detection signal amplifier. The detection of the CRP antigen using sandwich pAb immunoassay improved LoD to 1.2 ng ml^-1, LoQ to 3.97 ng ml^-1, and enhanced the sensitivity to 0.885 kΩ ng^-1 ml cm^-2. The real sample analysis, using newborn calf serum, showed excellent selectivity and % recovery for the human CRP ranging from 91.2 to 96.5%. The method was reproducible to 4.5% for direct immunoassay and 2.3% for sandwich immunoassay.

Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

Recent advances in developing biosensing based platforms for neonatal sepsis

Neonatal sepsis is a bloodstream infection primarily caused by Escherichia coli (E. coli), Group B Streptococcus (GBS), Listeria monocytogenes, Haemophilus influenzae, S. aureus, Klebsiella spp. and non-typhoidal Salmonella bacteria. Neonatal Sepsis is referred as a critical response to the infection in the neonatal period that can lead to the failure of body organs and thereby causing damage to the tissues resulting in death of the neonates. Nearly 4 million deaths across the world are occurred due to neonatal sepsis infections. In order to prevent the bloodstream infections in the neonates, it is indispensable to diagnose the disease properly for appropriate treatment during the point of care. Numerous studies have been reported to identify major biomarkers associated with neonatal sepsis including Serum Amyloid A (SAA), C - reactive protein (CRP), Procalcitonin (PCT) and Lipopolysaccharide-binding protein (LBP). Distinct diagnostic platforms have also been developed detecting the presence of bloodstream infections including electrochemical, potentiometric, and impedimetric sensors. Recently, electrochemical biosensors with the integration of nanomaterials have emerged as a better platform for neonatal sepsis biomarkers detection. This review article summarizes the diverse screening platforms, evaluation parameters, and new advances based on implications of nanomaterials for the development of biosensors detecting neonatal sepsis infections. The review further elucidates the significance and future scope of distinctive platforms which are predominantly associated with detection of neonatal sepsis.

Correlation between C-reactive Protein with Malondialdehyde in Systemic Lupus Erythematosus Patients

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by an inflammatory process. One of the inflammation markers that can be measured is C-reactive protein (CRP). Another indicator of inflammation is malondialdehyde (MDA), though it is still uncommon to be analyzed in SLE patients. The study looked for the MDA value and found a correlation with CRP. A cross-sectional study design with a correlative analytical was performed. CRP level data was taken from Hasan Sadikin lupus registry data, and MDA levels were analyzed from a bioarchive patient's serum. We collected the patients' data who had CRP level from Hasan Sadikin lupus registry and analysed MDA levels from the serum sample. MDA levels were analyzed using an ELISA method. The data obtained were analyzed using the Pearson correlation and Eta correlation test. The study involved 78 data patients as subjects. It was found that the median of CRP and MDA was 0.85 mg/l and 153.10 ng/ml, respectively. These results indicate that the CRP levels in SLE patients are still within normal limits. Statistical analysis showed no correlation between CRP and MDA level (r = 0.2, P > 0.05). Additionally, the correlation between CRP and MDA with organ involvement, such as lupus nephritis (LN), lupus cutaneous (LC), and lupus musculoskeletal (LM), showed no correlation (F_h < F_t). There is no correlation between CRP and MDA levels in SLE patients, and specific organ involvement of the disease does not affect the correlation.

Detection of Cardiovascular CRP Protein Biomarker Using a Novel Nanofibrous Substrate

It is known that different diseases have characteristic biomarkers that are secreted very early on, even before the symptoms have developed. Before any kind of therapeutic approach can be used, it is necessary that such biomarkers be detected at a minimum concentration in the bodily fluids. Here, we report the fabrication of an interdigitated sensing device integrated with polyvinyl alcohol (PVA) nanofibers and carbon nanotubes (CNT) for the detection of an inflammatory biomarker, C-reactive protein (CRP). The limit of detection (LOD) was achieved in a range of 100 ng mL-1 and 1 fg mL-1 in both phosphate buffered saline (PBS) and human serum (hs). Furthermore, a significant change in the electrochemical impedance from 45% to 70% (hs) and 38% to 60% (PBS) over the loading range of CRP was achieved. The finite element analysis indicates that a non-redox charge transduction at the solid/liquid interface on the electrode surface is responsible for the enhanced sensitivity. Furthermore, the fabricated biosensor consists of a large electro-active surface area, along with better charge transfer characteristics that enabled improved specific binding with CRP. This was determined both experimentally and from the simulated electrochemical impedance of the PVA nanofiber patterned gold electrode.

Electroimmunodetection of cardiac C-reactive protein for determining myocardial Injury

C-reactive protein (CRP) is an acute phase reactant to be a marker of inflammation and has been correlated with the cardiac injury. An immunoassay was performed using anti-human CRP antibody on an InterDigitated electrode (IDE) sensor to determine and specify CRP concentration for diagnosing the condition of myocardial inflammation. To promote the detection, gold nanoparticle (GNP) was seeded on the aminated-IDE surface. Anti-CRP was hitched on the GNP-seeded surface and identified the abundance of CRP. The limit of quantification was found as 100 fM, and the higher current response was noticed by increasing CRP concentrations with the sensitivity at 1 pM. Furthermore, CRP-spiked human serum did not interfere the determination of CRP and increased the current response, indicating suitability for a real-life sample. Similarly, the control experiments with nonimmune antibody Troponin I are not showing the definite current responses, proving the selective identification of CRP. This method of diagnosing is needful to determine the cardiovascular injury at the right time.

On-the-fly rapid immunoassay for neonatal sepsis diagnosis: C-reactive protein accurate determination using magnetic graphene-based micromotors

Based on the exceptional and new opened biosensing possibilities of self-propelled micromotors, a micromotor-based immunoassay (MIm) has smartly been designed for C-reactive protein (CRP) determination in plasma of preterm infants with sepsis suspicion. The design of the micromotors involved the electrosynthesis of a carbon-based outer layer (for antibody functionalization), an intermediate Ni layer (for magnetic guidance and stopped flow operations) and PtNPs inner catalytic layer (for catalytic bubble propulsion). Micromotors biofunctionalization on the outer layer (using carbon black (CB), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), and biocompatible propulsion capabilities, were carefully studied. Magnetic rGO/Ni/PtNPs micromotors exhibited the most efficient and reproducible (CV = 9%) anti-CRP functionalization, controlled stopped-flow operations as well as efficient bubble propulsion (1% H₂O₂, 1,5% NaCh, speed 140 μm s^-1). Analytical performance of MIm was excellent, allowing the direct (without dilution), sensitive (LOD = 0.80 μg/mL), and accurate CRP determination (E_r = 1%) in hardly available preterm babies' plasma samples with suspected sepsis using very low volumes (<10 μL) and in just 5 min of on-the-fly bioassay. Overall, the results obtained allowed the fast and reliable sepsis diagnostics in preterm babies' individuals with suspected sepsis, not only proving the usefulness of the approach as its potential utilization as point-of-care device for clinical analysis but drawing new horizons in extremely low sample volumes-based diagnostics.

Electrochemical Detection of C-Reactive Protein in Human Serum Based on Self-Assembled Monolayer-Modified Interdigitated Wave-Shaped Electrode

An electrochemical capacitance immunosensor based on an interdigitated wave-shaped micro electrode array (IDWµE) for direct and label-free detection of C-reactive protein (CRP) was reported. A self-assembled monolayer (SAM) of dithiobis (succinimidyl propionate) (DTSP) was used to modify the electrode array for antibody immobilization. The SAM functionalized electrode array was characterized morphologically by atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDX). The nature of gold-sulfur interactions on SAM-treated electrode array was probed by X-ray photoelectron spectroscopy (XPS). The covalent linking of anti-CRP-antibodies onto the SAM modified electrode array was characterized morphologically through AFM, and electrochemically through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The application of phosphate-buffered saline (PBS) and human serum (HS) samples containing different concentrations of CRP in the electrode array caused changes in the electrode interfacial capacitance upon CRP binding. CRP concentrations in PBS and HS were determined quantitatively by measuring the change in capacitance (ΔC) through EIS. The electrode immobilized with anti-CRP-antibodies showed an increase in ΔC with the addition of CRP concentrations over a range of 0.01-10,000 ng mL-1. The electrode showed detection limits of 0.025 ng mL-1 and 0.23 ng mL-1 (S/N = 3) in PBS and HS, respectively. The biosensor showed a good reproducibility (relative standard deviation (RSD), 1.70%), repeatability (RSD, 1.95%), and adequate selectivity in presence of interferents towards CRP detection. The sensor also exhibited a significant storage stability of 2 weeks at 4 °C in 1× PBS.

Nanosensors for therapeutic drug monitoring: implications for transplantation

The number of patients requiring organ transplantations is exponentially increasing. New organs are either provided by healthy or deceased donors, or are grown in laboratories by tissue engineers. Post-surgical follow-up is vital for preventing any complications that can cause organ rejection. Physiological monitoring of a patient who receives newly transplanted organs is crucial. Many efforts are being made to enhance follow-up technologies for monitoring organ recipients, and point-of-care devices are beginning to emerge. Here, we describe the role of biosensors and nanosensors in improving organ transplantation efficiency, managing post-surgical follow-up and reducing overall costs. We provide an overview of the state-of-the-art biosensing technologies and offer some perspectives related to their further development.

Plasma levels of C-reactive protein, matrix metalloproteinase-7 and lipopolysaccharide-binding protein distinguish active pulmonary or extrapulmonary tuberculosis from uninfected controls in children

The immune profile associated with distinct clinical forms of tuberculosis (TB) has been extensively described for adult populations. Nevertheless, studies describing immune determinants of pulmonary or extrapulmonary TB (PTB or EPTB, respectively) in children are scarce. Here, we retrospectively assessed plasma levels of several mediators of inflammation in age and sex-matched children from South India presenting with PTB (n = 14) or EPTB (n = 22) as well as uninfected healthy controls (n = 19) to identify biomarkers that could accurately distinguish different TB clinical forms. Furthermore, we performed exploratory analyses testing the influence of sex on the systemic inflammatory profile. The analyses identified a biosignature of 10 biomarkers capable of distinguishing the three clinical groups simultaneously. Machine-learning decision trees indicated that C-reactive protein (CRP), matrix metalloproteinase (MMP)-7 and lipopolysaccharide-binding protein (LBP) were the markers that, when combined, displayed the highest accuracy in identifying the clinical groups. Additional exploratory analyses suggested that the disease signatures were highly influenced by sex. Therefore, sex differentially impacted status of systemic inflammation, immune activation and tissue remodeling in children with distinct clinical forms of TB. Regardless of such nuances related to biological sex, MMP-7, CRP and LBP were strong discriminators of active TB and thus could be considered as biomarkers useful in discrimination different TB clinical forms. These observations have implications on our understanding of the immunopathology of both clinical forms of TB in pediatric patients. If validated by other studies in the future, the combination of identified biomarkers may help development of point-of-care diagnostic or prognostic tools.

An integrated microfluidic system with field-effect-transistor sensor arrays for detecting multiple cardiovascular biomarkers from clinical samples

Certain blood-borne biomarkers offer a potent methodology for understanding the risk of cardiovascular diseases (CVDs) with clinicians generally advocating the use of multiple biomarkers for proper risk assessment of CVDs. Herein four such CVDs biomarkers- C-reactive protein (CRP), N-terminal pro b-type natriuretic peptide (NT-proBNP), cardiac troponin I (cTnI), and fibrinogen- were rapidly (5 min) analyzed from clinical samples (~ 4 µL) on an integrated microfluidic platform equipped with 1) immobilized highly specific aptamer probes and 2) field-effect transistor (FET)-based sensor arrays. The calibration curve from the FET sensor arrays showed good agreement in the physiological concentration ranges for CRP (0.1-50 mg/L), NT-proBNP (50-10,000 pg/mL), cTnI (1-10,000 pg/mL), and fibrinogen (0.1-5 mg/mL). The developed prototype of this fully automated portable device requires minimal reagent and sample inputs and consequently shows great promise for next-generation point-of-care devices assaying multiple CVDs biomarkers in clinical samples.

A novel nanozyme assay utilising the catalytic activity of silver nanoparticles and SERRS

Artificial enzymes have become an increasingly interesting area of research due to their many advantages over natural protein enzymes which are expensive, difficult to isolate and unable to stand harsh environments. An important area of this research involves using metal nanoparticles as artificial enzymes, known as nanozymes, which exhibit peroxidase-like activity enabling them to catalyse the oxidation of substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H₂O₂), giving a colorimetric response. Here we exploit the catalytic activity of silver nanoparticles (Ag NPs) in a surface based silver-linked immunosorbent assay (SLISA) to detect human C-reactive protein (CRP), an inflammatory marker. Ag NPs were conjugated to antibodies with specific recognition for the corresponding target antigenic molecule, CRP, and the Ag NPs were used to catalyse the oxidation of TMB by H₂O₂. The resulting coloured oxidation product was detected using SERRS. We demonstrate that Ag NPs can replace the enzymes used in a conventional ELISA and a detection limit of 1.09 ng mL^-1 of CRP can be achieved. It indicates the promise for SLISAs for biomarker detection and opens the way for further assays of this nature to be created. This novel assay has the potential to be optimised to detect lower levels of CRP and can be further extended for the sensitive and specific detection of other relevant biomarkers.

Recent progress on the sensitive detection of cardiovascular disease markers by electrochemical-based biosensors

Cardiovascular disease is the most reason for deaths in all over the world. Hence, biomarkers of cardiovascular diseases are very crucial for diagnosis and management process. Biomarker detection demand is opened the important way in biosensor development field. Rapid, cheap, portable, precise, selective and sensitive biomarker sensing devices are needed at this point to detect and predict disease. A cardiac biomarker can be orderable as C-reactive protein, troponin I or T, myoglobin, tumor necrosis factor alpha, interleukin-6, interleukin-1, lipoprotein-associated phospholipase, low-density lipoprotein and myeloperoxidase. They are used for prediction of cardiovascular diseases. There are many methods for early diagnosis of cardiovascular diseases, but these have long time process and expensive devices. In recent studies, different biosensors have been developed to remove the problems in this field. Electrochemical devices and developed biosensors have many superiorities than others such as low cost, mobile, reliable, repeatable, need a little amount of solution. In this review, recent studies were presented as details for cardiovascular disease biomarkers detection using electrochemical methods.

Label-Free Electrochemical Immunoassay for C-Reactive Protein

C-reactive protein (CRP) is one of the most expressed proteins in blood during acute phase inflammation, and its minute level increase has also been recognized for the clinical diagnosis of cardio vascular diseases. Unfortunately, the available commercial immunoassays are labour intensive, require large sample volumes, and have practical limitations, such as low stability and high production costs. Hence, we have developed a simple, cost effective, and label-free electrochemical immunoassay for the measurement of CRP in a drop of serum sample using an immunosensor strip made up of a screen printed carbon electrode (SPE) modified with anti-CRP functionalized gold nanoparticles (AuNPs). The measurement relies on the decrease of the oxidation current of the redox indicator Fe³⁺/Fe²⁺, resulting from the immunoreaction between CRP and anti-CRP. Under optimal conditions, the present immunoassay measures CRP in a linear range from 0.4–200 nM (0.047–23.6 µg mL⁻¹), with a detection limit of 0.15 nM (17 ng mL⁻¹, S/N = 3) and sensitivity of 90.7 nA nM⁻¹, in addition to a good reproducibility and storage stability. The analytical applicability of the presented immunoassay is verified by CRP measurements in human blood serum samples. This work provides the basis for a low-priced, safe, and easy-to-use point-of-care immunosensor assay to measure CRP at clinically relevant concentrations.

Sensors and Biosensors for C-Reactive Protein, Temperature and pH, and Their Applications for Monitoring Wound Healing: A Review

Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in sensors and biosensors for monitoring the concentration of C-reactive protein (CRP), temperature and pH in wounds. These three parameters can be used as qualitative biomarkers to assess the wound status and the effectiveness of therapy. CRP biosensors can be classified in: (a) field effect transistors, (b) optical immunosensors based on surface plasmon resonance, total internal reflection, fluorescence and chemiluminescence, (c) electrochemical sensors based on potentiometry, amperometry, and electrochemical impedance, and (d) piezoresistive sensors, such as quartz crystal microbalances and microcantilevers. The last section reports the most recent developments for wearable non-invasive temperature and pH sensors suitable for wound monitoring.

Design of a New Ultracompact Resonant Plasmonic Multi-Analyte Label-Free Biosensing Platform

In this paper, we report on the design of a bio-multisensing platform for the selective label-free detection of protein biomarkers, carried out through a 3D numerical algorithm. The platform includes a number of biosensors, each of them is based on a plasmonic nanocavity, consisting of a periodic metal structure to be deposited on a silicon oxide substrate. Light is strongly confined in a region with extremely small size (=1.57 μm²), to enhance the light-matter interaction. A surface sensitivity S_s = 1.8 nm/nm has been calculated together with a detection limit of 128 pg/mm². Such performance, together with the extremely small footprint, allow the integration of several devices on a single chip to realize extremely compact lab-on-chip microsystems. In addition, each sensing element of the platform has a good chemical stability that is guaranteed by the selection of gold for its fabrication.

Poly(3,4-ethylenedioxythiophene) Bearing Phosphorylcholine Groups for Metal-Free, Antibody-Free, and Low-Impedance Biosensors Specific for C-Reactive Protein

Conducting polymers possessing biorecognition elements are essential for developing electrical biosensors sensitive and specific to clinically relevant biomolecules. We developed a new 3,4-ethylenedioxythiophene (EDOT) derivative bearing a zwitterionic phosphorylcholine group via a facile synthesis through the Michael-type addition thiol-ene "click" reaction for the detection of an acute-phase biomarker human C-reactive protein (CRP). The phosphorylcholine group, a major headgroup in phospholipid, which is the main constituent of plasma membrane, was also expected to resist nonspecific adsorption of other proteins at the electrode/solution interface. The biomimetic EDOT derivative was randomly copolymerized with EDOT, via an electropolymerization technique with a dopant sodium perchlorate, onto a glassy carbon electrode to make the synthesized polymer film both conductive and target-responsive. The conducting copolymer films were characterized by cyclic voltammetry, scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The specific interaction of CRP with phosphorylcholine in a calcium-containing buffer solution was determined by differential pulse voltammetry, which measures the altered redox reaction between the indicators ferricyanide/ferrocyanide as a result of the binding event. The conducting polymer-based protein sensor achieved a limit of detection of 37 nM with a dynamic range of 10-160 nM, covering the dynamically changing CRP levels in circulation during the acute phase. The results will enable the development of metal-free, antibody-free, and low-impedance electrochemical biosensors for the screening of nonspecific biomarkers of inflammation and infection.

Electrochemiluminescence platform for the detection of C-reactive proteins: application of recombinant antibody technology to cardiac biomarker detection

The stepwise fabrication of the sensor is highlighted, scFv immobilization, binding of pentameric CRP followed by binding of metal labeled scFv fragments.