Development of a Lateral Flow Highway: Ultra-Rapid Multitracking Immunosensor for Cardiac Markers (original) (raw)
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Point-of-Care Testing for Multiple Cardiac Markers Based on a Snail-Shaped Microfluidic Chip
Frontiers in Chemistry, 2021
Existing methods for detecting cardiac markers are difficult to be applied in point-of-care testing (POCT) due to complex operation, long time consumption, and low sensitivity. Here, we report a snail-shaped microfluidic chip (SMC) for the multiplex detection of cTnI, CK-MB, and Myo with high sensitivity and a short detection time. The SMC consists of a sandwich structure: a channel layer with a mixer and reaction zone, a reaction layer coated with capture antibodies, and a base layer. The opening or closing of the microchannels is realized by controlling the downward movement of the press-type mechanical valve. The chemiluminescence method was used as a signal readout, and the experimental conditions were optimized. SMC could detect cTnI, CK-MB, and Myo at concentrations as low as 1.02, 1.37, and 4.15. The SMC will be a promising platform for a simultaneous determination of multianalytes and shows a potential application in POCT.
2010
A microsystem allowing direct and simultaneous analysis of multiple cardiac biomarkers in blood using an integrated filter chip and silicon nanowire (SiNW) sensor chip is described. The integrated microsystem is composed of the filter chip for plasma separation from blood and the SiNW sensor chip for protein detection. These two chips were fabricated into one via back-to-back integration. The SiNW sensor, spotted with three different antibodies, enabled us to detect three cardiac biomarkers, cTnT, CK-MM and CK-MB, simultaneously. The system is able to attain a low detection limit of 1 pg/ml for the three cardiac biomarkers from 2 µl blood in 45 minutes.
Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays
Nature Protocols, 2020
Lateral flow assays (LFA) are quick, simple and cheap assays to analyse a variety of samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample within a series of sequential pads with different functionalities aiming to generate a signal indicating the absence/presence (and, in some cases, the concentration) of the analyte of interest. In order to have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this Tutorial we provide the readers with: 1) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, 2) a roadmap for optimal LFA development independent of the specific application, 3) a step by step example protocol for the assembly and operation of an LF strip for the detection of Human Immunoglobulin G and 4) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs.
2006
Miniaturised point-of-care cardiac marker sensors are being developed, based on impedimetric sensing of cardiac enzyme capture by an antibody layer immobilised on a planar gold electrode sensor. Gold/Ti-on-glass substrates have been used, in a 2 electrode configuration, with antibodies immobilised on the working electrode. Microfluidic structures have been fabricated by a CO2 laser, in 25 mum thick pressure sensitive adhesive (PSA), on a PMMA lid, and the structure bonded on top of the planar sensor. Microfluidic blood/serum delivery has been investigated using a visualisation dye. Some flow problems are observed if the sensor is exposed to air for several days, suggesting that flow channel nanopillars and hermetic encapsulation may be required to guarantee flow properties in commercially produced modules. Work is ongoing to characterise the impedimetric signal changes for myoglobin capture by antimyoglobin, using these sensors. Fifty micron thick PSA, incorporating a robust spacer layer, will be used to give better definition of channel walls
Lateral Flow Immunoassays - from Paper Strip to Smartphone Technology
Electroanalysis, 2015
Our modernw orld is exposed to constant health threats, be they natural from epidemics,o r, man-made,s uch as irresponsible food chain supervision or environmental pollution, and of course,t here is alwayst he possible bioterrorism hangingo ut there.W et herefore need to constantly monitor for both etiological agents, as well as,o ur response to them, througho ur adaptive immune response, namelyo ur elicited immunoglobulins.M any methods exist enablingt he identification of pathogens,i ncluding cell culture,i mmunoassays and nucleica cid related tests. However, of prime importance would be enabling methodologies bringing us boths peed, as wella s, sensitivity, while ensuring specificity.T hese features are generally found under the umbrella of point-of-careo ro n-site measurements.Aworldwide demand has encouraged bringing to market av ariety of systems,i ncludingo ne of the most successfulo ne,t he lateral flow immunoassay (LFA), introduced by Unipath in 1988. Its convenience and success made it the most commercially available POC diagnostic format [1].B y2 010, over 100 companies worldwide produceawide range of such tests with at otal marketv alued at over 3.36 billion USD [2].T heir success is due to the fact that they include av ariety of advantageous parameters,i ncludingc ost efficiency, portability, simplicity of use and speed, whicha re not altogether found in other conventional detection approaches (e.g. ELISA, PCR,c ell culture). Theo verall format of LFA uses the same rationale as ELISA, where immobilized capturea ntibodyo ra ntigen is bound onto as olid phase nitrocellulose membrane instead of ap lastic well. Thea dvantageh ere is the fact that the membranee nables ao ne-step assay,u nliket hat found in the multiple-step ELISA. At ypical LFAs tructure is based on fours egments, asamplepad, aconjugate pad, anitrocellulose membrane and an absorbent pad, eachs erving ag iven purpose,o verlapping one another and combined together on ap lastic backing support (Figure 1). Each segment is overlapped by 2mmt oa llow the migration of as ample solution along the LFAd uring the analysis. In short, the assay rationale consists in as ample being added onto the sample pad, which it permeates,b efore migrating to the conjugation pad where it interacts with gold nanoparticles previ
Analytical Chemistry, 2007
We describe a novel microfluidic immunoassay method based on the diffusion of a small molecule analyte into a parallel-flowing stream containing cognate antibody. This interdiffusion results in a steady-state gradient of antibody binding site occupancy transverse to convective flow. In contrast to the diffusion immunoassay (Hatch et al. Nature Biotechnology,19:461−465 (2001)), this antibody occupancy gradient is interrogated by a sensor surface coated with a functional analog of the analyte. Antibodies with at least one unoccupied binding site may specifically bind to this functionalized surface, leading to a quantifiable change in surface coverage by the antibody. SPR imaging is used to probe the spatial distribution of antibody binding to the surface and, therefore, the outcome of the assay. We show that the pattern of antibody binding to the SPR sensing surface correlates with the concentration of a model analyte (phenytoin) in the sample stream. Using an inexpensive disposable microfluidic device, we demonstrate assays for phenytoin ranging in concentration from 75 to 1000 nM in phosphate buffer. At a total volumetric flow rate of 90 nL/sec, the assays are complete within 10 minutes. Inclusion of an additional flow stream on the side of the antibody stream opposite to that of the sample enables simultaneous calibration of the assay. This assay method is suitable for rapid quantitative detection of low-molecular weight analytes for point-of-care diagnostic instrumentation.
Biosensors and Bioelectronics, 2004
We show a proof-of-concept in which we combine our previously published concepts of micromosaic immunoassays (MIAs) with self-regulating microfluidic networks (FNs) to detect C-reactive protein (CRP) and other cardiac markers such as myoglobin (Mb) and cardiac Troponin I (cTnI). The FNs are microfabricated in Si, have a well-defined surface chemistry, and are affixed to a bibulous material so as to self-regulate the displacement of an aliquot of liquid through the FNs using capillary forces. An open section of the channels of the FNs is covered with a hydrophobic poly(dimethylsiloxane) (PDMS) slab that acts as the substrate for a solid-phase immunoassay.
Multiplexing of highly reproducible, bead-based immunoassays on a centrifugal microfluidic platform
2011 IEEE 24th International Conference on Micro Electro Mechanical Systems, 2011
This work demonstrates for the first time integrated and highly multiplexable immunoassays on single beads on a centrifugal microfluidic platform. Sharply peaked, singleoccupancy distributions of the monodisperse beads are achieved by a stopped-flow, merely sedimentation-based introduction of the beads to an array of scale-matched geometrical barriers. Compared to statistically aggregated beads, our here presented single-bead scheme offers homogeneous flow conditions throughout the spatially separated trapping sites.