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

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

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.

scholarly journals Hepcidin is the major predictor of erythrocyte iron incorporation in anemic African children

Blood ◽  
2012 ◽  
Vol 119 (8) ◽  
pp. 1922-1928 ◽  
Author(s):  
Andrew M. Prentice ◽  
Conor P. Doherty ◽  
Steven A. Abrams ◽  
Sharon E. Cox ◽  
Sarah H. Atkinson ◽  
...  
Keyword(s):  
Iron Supplementation ◽  
Developing World ◽  
Point Of Care ◽  
Low Cost ◽  
C Reactive Protein ◽  
Iron Supplements ◽  
Reactive Protein ◽  
Iron Incorporation ◽  
Major Predictor ◽  
Univariate Analyses

AbstractIron supplementation strategies in the developing world remain controversial because of fears of exacerbating prevalent infectious diseases. Understanding the conditions in which iron will be absorbed and incorporated into erythrocytes is therefore important. We studied Gambian children with either postmalarial or nonmalarial anemia, who were given oral iron supplements daily for 30 days. Supplements administered on days 1 and 15 contained the stable iron isotopes 57Fe and 58Fe, respectively, and erythrocyte incorporation was measured in blood samples drawn 14 days later. We investigated how the iron-regulatory hormone hepcidin and other inflammatory/iron-related indices, all measured on the day of isotope administration, correlated with erythrocyte iron incorporation. In univariate analyses, hepcidin, ferritin, C-reactive protein, and soluble transferrin receptor (sTfR) strongly predicted incorporation of 57Fe given on day 1, while hepcidin, ferritin, and sTfR/log ferritin correlated with 58Fe incorporation. In a final multivariate model, the most consistent predictor of erythrocyte isotope incorporation was hepcidin. We conclude that under conditions of competing signals (anemia, iron deficiency, and infection), hepcidin powerfully controls use of dietary iron. We suggest that low-cost point-of-care hepcidin assays would aid iron supplementation programs in the developing world.

scholarly journals Whole Blood Immunoassay Based on Centrifugal Bead Sedimentation

2011 ◽  
Vol 57 (5) ◽  
pp. 753-761 ◽  
Author(s):  
Ulrich Y Schaff ◽  
Greg J Sommer
Keyword(s):  
Whole Blood ◽  
Single Channel ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Microfluidic System ◽  
Blood Samples ◽  
Reactive Protein ◽  
Immunoassay Technique ◽  
Microfluidic Immunoassay

BACKGROUND Centrifugal “lab on a disk” microfluidics is a promising avenue for developing portable, low-cost, automated immunoassays. However, the necessity of incorporating multiple wash steps results in complicated designs that increase the time and sample/reagent volumes needed to run assays and raises the probability of errors. We present proof of principle for a disk-based microfluidic immunoassay technique that processes blood samples without conventional wash steps. METHODS Microfluidic disks were fabricated from layers of patterned, double-sided tape and polymer sheets. Sample was mixed on-disk with assay capture beads and labeling antibodies. Following incubation, the assay beads were physically separated from the blood cells, plasma, and unbound label by centrifugation through a density medium. A signal-laden pellet formed at the periphery of the disk was analyzed to quantify concentration of the target analyte. RESULTS To demonstrate this technique, the inflammation biomarkers C-reactive protein and interleukin-6 were measured from spiked mouse plasma and human whole blood samples. On-disk processing (mixing, labeling, and separation) facilitated direct assays on 1-μL samples with a 15-min sample-to-answer time, <100 pmol/L limit of detection, and 10% CV. We also used a unique single-channel multiplexing technique based on the sedimentation rate of different size or density bead populations. CONCLUSIONS This portable microfluidic system is a promising method for rapid, inexpensive, and automated detection of multiple analytes directly from a drop of blood in a point-of-care setting.

Rapid C-reactive protein determination in whole blood with a White Light Reflectance Spectroscopy label-free immunosensor for Point-of-Care applications

2018 ◽  
Vol 260 ◽  
pp. 282-288 ◽  
Author(s):  
Georgios Koukouvinos ◽  
Dimitrios Goustouridis ◽  
Konstantinos Misiakos ◽  
Sotirios Kakabakos ◽  
Ioannis Raptis ◽  
...  
Keyword(s):  
White Light ◽  
Whole Blood ◽  
Point Of Care ◽  
Reflectance Spectroscopy ◽  
Label Free ◽  
C Reactive Protein ◽  
Protein Determination ◽  
Reactive Protein ◽  
Light Reflectance

scholarly journals Label-Free Optical Resonator-Based Biosensors

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5901
Author(s):  
Donggee Rho ◽  
Caitlyn Breaux ◽  
Seunghyun Kim
Keyword(s):  
Point Of Care ◽  
Health And Safety ◽  
Disease Diagnosis ◽  
Medical Diagnostics ◽  
Sample Volume ◽  
Small Sample ◽  
Optical Resonator ◽  
Future Research ◽  
Label Free ◽  
Label Free Detection

The demand for biosensor technology has grown drastically over the last few decades, mainly in disease diagnosis, drug development, and environmental health and safety. Optical resonator-based biosensors have been widely exploited to achieve highly sensitive, rapid, and label-free detection of biological analytes. The advancements in microfluidic and micro/nanofabrication technologies allow them to be miniaturized and simultaneously detect various analytes in a small sample volume. By virtue of these advantages and advancements, the optical resonator-based biosensor is considered a promising platform not only for general medical diagnostics but also for point-of-care applications. This review aims to provide an overview of recent progresses in label-free optical resonator-based biosensors published mostly over the last 5 years. We categorized them into Fabry-Perot interferometer-based and whispering gallery mode-based biosensors. The principles behind each biosensor are concisely introduced, and recent progresses in configurations, materials, test setup, and light confinement methods are described. Finally, the current challenges and future research topics of the optical resonator-based biosensor are discussed.

scholarly journals Ultra-low HIV-1 p24 detection limits with a bioelectronic sensor

2019 ◽  
Vol 412 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Eleonora Macchia ◽  
Lucia Sarcina ◽  
Rosaria Anna Picca ◽  
Kyriaki Manoli ◽  
Cinzia Di Franco ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Single Molecule ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Wide Field ◽  
Label Free ◽  
Limit Of Quantification ◽  
Great Relevance ◽  
Hiv 1

AbstractEarly diagnosis of the infection caused by human immunodeficiency virus type-1 (HIV-1) is vital to achieve efficient therapeutic treatment and limit the disease spreading when the viremia is at its highest level. To this end, a point-of-care HIV-1 detection carried out with label-free, low-cost, and ultra-sensitive screening technologies would be of great relevance. Herein, a label-free single molecule detection of HIV-1 p24 capsid protein with a large (wide-field) single-molecule transistor (SiMoT) sensor is proposed. The system is based on an electrolyte-gated field-effect transistor whose gate is bio-functionalized with the antibody against the HIV-1 p24 capsid protein. The device exhibits a limit of detection of a single protein and a limit of quantification in the 10 molecule range. This study paves the way for a low-cost technology that can quantify, with single-molecule precision, the transition of a biological organism from being “healthy” to being “diseased” by tracking a target biomarker. This can open to the possibility of performing the earliest possible diagnosis.

scholarly journals Label free, electric field mediated ultrasensitive electrochemical point-of-care device for CEA detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Chakraborty ◽  
A. Das ◽  
N. Mandal ◽  
N. Samanta ◽  
N. Das ◽  
...  
Keyword(s):  
Electric Field ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Zno Nanorods ◽  
Hybrid Nanostructures ◽  
Electrochemical Sensing ◽  
Label Free ◽  
Electron Transfer Rate

AbstractDeveloping point-of-care (PoC) diagnostic platforms for carcinoembryonic antigen detection is essential. However, thefew implementations of transferring the signal amplification strategies in electrochemical sensing on paper-based platforms are not satisfactory in terms of detection limit (LOD). In the quest for pushing down LOD, majority of the research has been targeted towards development of improved nanostructured substrates for entrapping more analyte molecules and augmenting the electron transfer rate to the working electrode. But, such approaches have reached saturation. This paper focuses on enhancing the mass transport of the analyte towards the sensor surface through the application of an electric field, in graphene-ZnO nanorods heterostructure. These hybrid nanostructures have been deposited on flexible polyethylene terephthalate substrates with screen printed electrodes for PoC application. The ZnO nanorods have been functionalized with aptamers and the working sensor has been integrated with smartphone interfaced indigenously developed low cost potentiostat. The performance of the system, requiring only 50 µl analyte has been evaluated using electrochemical impedance spectroscopy and validated against commercially available ELISA kit. Limit of detection of 1 fg/ml in human serum with 6.5% coefficient of variation has been demonstrated, which is more than three orders of magnitude lower than the existing attempts on PoC device.

scholarly journals A Low-Cost Micro-Volume Nephelometric System for Quantitative Immunoagglutination Assays

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4359 ◽  
Author(s):  
Qiqi Sun ◽  
Wei Zheng ◽  
Chao Lin ◽  
Dongxuan Shen
Keyword(s):  
Low Cost ◽  
Protein A ◽  
High Sensitivity ◽  
High Specificity ◽  
Sample Volume ◽  
C Reactive Protein ◽  
Detection Capability ◽  
Reactive Protein ◽  
Detection Volume ◽  
Reagent Cost

Immunoassays have been widely used in scientific research and clinical diagnosis due to their versatile detection capability and high specificity. Immunoagglutination assays are kinds of immunoassay, which can simply and rapidly measure the concentration of analytes. In this work, we developed a low-cost micro-volume nephelometric system for quantitative immunoagglutination assays. We used off-the-shelf components to build the system, and the total cost of key components is only about 20 US dollars. The total detection volume in our system was as low as 3 µL, which could significantly reduce the reagent cost and required sample volume. We further evaluated the system performance via the immunoagglutination assay to measure the concentration of C-reactive protein, a plasma protein with levels rising in response to inflammation. The results demonstrated that our system could measure the concentration of analytes with relatively high sensitivity and precision within four minutes, and has high potential to be applied for clinical diagnostic tests.

scholarly journals Demonstration of a Low-Cost and Portable Optical Cavity-Based Sensor through Refractive Index Measurements

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2193 ◽  
Author(s):  
Donggee Rho ◽  
Caitlyn Breaux ◽  
Seunghyun Kim
Keyword(s):  
Refractive Index ◽  
Detection Method ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Differential Detection ◽  
Low Pass ◽  
Portable System ◽  
Simulation Results

An optical cavity-based sensor using a differential detection method has been proposed for point-of-care diagnostics. We developed a low-cost and portable optical cavity-based sensor system using a 3D printer and off-the-shelf optical components. In this paper, we demonstrate the sensing capability of the portable system through refractive index measurements. Fabricated optical cavity samples were tested using the portable system and compared to simulation results. A referencing technique and digital low pass filtering were applied to reduce the noise of the portable system. The measurement results match the simulation results well and show the improved linearity and sensitivity by employing the differential detection method. The limit of detection achieved was 1.73 × 10−5 Refractive Index Unit (RIU), which is comparable to other methods for refractive index sensing.

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

2021 ◽  
Vol 9 ◽  
Author(s):  
Abiola Adesina ◽  
Philani Mashazi
Keyword(s):  
Linear Dependence ◽  
Boronic Acid ◽  
Limit Of Detection ◽  
Covalent Immobilization ◽  
Sandwich Immunoassay ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Direct Immunoassay ◽  
Signal Amplifier

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.

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