![]() Many other lateral flow applications fall in between the 2 extremes, demanding high performance and ease of use, coupled with mobile technology for high-end field-based applications. These high-performance assays use lateral flow strips combined with specialized readers, sample handling devices, and cartridges with onboard functionality-essentially creating laboratory analyzers based on the lateral flow format. Applications in the developed world have taken advantage of the improved performance to generate LFA performance equivalent to that available with complicated laboratory-based formats. These advances led to improved applications for LFAs in decentralized testing environments, medical, and others. Recent advances in reagents, materials and manufacturing processes improved LFA performance in applications requiring higher accuracy and sensitivity while maintaining the advantages of the basic technology. LFAs have been associated with the latter environments the technology was considered a cheap solution to simple problems. The ability to provide accurate information for diagnostic technologies ranges from highly accurate methods requiring infrastructure and centralized laboratories to less accurate technologies that can be used in decentralized environments, and point-of-care or even home settings. It is imperative diagnostic assays provide accurate information to decision makers to have value to end-users. Results are interpreted on the nitrocellulose membrane as the presence/absence of lines of captured conjugate, interpreted either by eye or by using a reader ( 1). Any excess reagents move past the capture lines and accumulate in the absorbent pad. These are generally proteins, either antibodies or antigens, that have been dispensed and dried in bands on the membrane where they capture the analyte and conjugate. Typically, the reaction matrix is a porous nitrocellulose membrane onto which the other biological components of the assay have been immobilized. When the sample rehydrates and mobilizes the dried conjugate, analyte in the sample interacts with the conjugate as both migrate into the next section of the strip, the reaction matrix. Treated sample then migrates onto the “conjugate pad,” containing immobilized conjugate, typically made of nanoparticles (e.g., colloidal gold, colored, or fluorescent latex, colored cellulose) conjugated to either antibodies or antigens. ![]() In general, to perform an LFA test, the sample is added to the proximal end of the strip, where a “sample application pad” supports sample treatment, making it compatible with other test elements. There are numerous publications describing the basic components, architecture and functions of LFA strips, including Brown ( 1) and O’Farrell ( 2). Those components are mounted on a backing card using pressure-sensitive adhesives. Traditionally designed lateral flow assays (LFAs) are composed of a variety of materials, each of them serving one or more purposes. ![]()
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