A timer-actuated immunoassay cassette for detecting molecular markers in oral fluids

Abstract

An inexpensive, hand-held, point-of-care, disposable, self-contained, immunoassay cassette comprised of air pouches for pumping, a metering chamber, reagents storage chambers, a mixer, and a lateral flow strip was designed, constructed, and tested. The assay was carried out in a consecutive flow format. The detection was facilitated with up-converting, phosphor (UCP) reporter particles. The automated, timely pumping of the various reagents was driven by a spring-loaded timer. The utility of the cassette was demonstrated by detecting antibodies to HIV in saliva samples and further evaluated with a non-contagious, haptenized DNA assay. The cassette has several advantages over dip sticks such as sample preprocessing, integrated storage of reagents, and automated operation that reduces operator errors and training. The cassette and actuator described herein can readily be extended to detect biomarkers of other diseases in body fluids and other fluids at the point of care. The system is particularly suitable for resource poor countries, where funds and trained personnel are in short supply.

Upconverting Phosphor Labels for Bioanalytical Assays

“…All operations are carried out automatically by the analyzer [155][156][157], and the result is obtained in less than 1 h, which sets strict time limits on each step [158]. Different versions of portable analyzers (manual, mechanical, or thermal actuations) with external LF strip scanner have been described [158][159][160].…”

Photonen aufkonvertierende Nanopartikel zur optischen Codierung und zum Multiplexing von Zellen, Biomolekülen und Mikrosphären

“…Die Nachweisgrenze der DNA-Hybridisierung auf einem Mikroarray verringerte sich um den Faktor 4 bei Verwendung der Aufkonvertierungstechnik anstelle von konventioneller Fluoreszenzmarkierung. [197] Solche aufkonvertierenden Partikel wurden in Teststreifen (lateral flow assay, LFA) für den Nachweis von DNA, [198,199] Pathogenen [200,201] und Proteinen [202] eingesetzt. In einem typischen LFA bindet der Analyt in einer Probe an ein Nachweisreagens (beispielsweise einen Antikçrper) und fließt anschließend über eine Nitrocellulosemembran mit einer Testlinie, auf der ein Analyt-spezifischer Fängeranti-kçrper immobilisiert ist, und einer weiteren Kontrolllinie, auf der sich ein Fängerantikçrper befindet, der das Nachweissystem bindet und somit anzeigt, ob der Assay funktioniert hat.…”

Pouch-Chip Immunoassays and Nucleic Acid Amplification Tests

“…Pouch chips have been demonstrated for both immunoassays [11][12][13] and NAATs [6]. Figure 1 shows a pouch chip immunoassay utilizing a conventional lateral flow strip.…”

“…sections of the chip are shown in Figure 3. Pouch chips can be manually operated, i.e., finger actuation of pouches [12], operated with a non-electrical mechanical actuator [11] or electromechanically with solenoid plungers which depress pouches and diaphragm valves [13].…”