A centrifugally actuated point-of-care testing system for the surface acoustic wave immunosensing of cardiac troponin I

Abstract

A fully automated point-of-care testing (POCT) system with a surface acoustic wave (SAW) immunosensor was developed for rapid and sensitive detection of cardiac troponin I (cTnI) in body fluid (plasma and whole blood). The assay, based on gold nanoparticle sandwich immunoassay and subsequent gold staining, was performed on the SAW immunosensor packaged inside a disposable microfluidic cartridge. The entire fluidic process, including plasma separation, reagent transport, metering, and mixing, was carried out by controlling the centrifugal force acting on the rotating cartridge and laser-irradiated ferrowax microvalves. On investigation of sensor response to various cTnI concentrations, the system exhibited a high performance with a detection limit of 6.7 pg mL(-1), and the coefficient of variation was less than 10% over the entire test range (10 pg mL(-1) to 25 ng mL(-1)). On comparing this POCT system with a clinically utilized system in a physical laboratory (Centaur® XP; Siemens), a correlation coefficient of 0.998 was found, validating the diagnostic capability of the SAW immunosensor.

Point-of-care diagnostics for niche applications

“…Lee et al (2013) recently introduced a centrifugally actuated POC testing system for cardiac troponin I. This microfluidic system performed a sandwich immunoassay with gold nanoparticles, and the fluid manipulation was controlled via centrifugation.…”

Sensitive detection of carcinoembryonic antigen in exhaled breath condensate using surface acoustic wave immunosensor

“…Since the sensitivity of these two piezoelectric sensors is proportional to the square of the resonance frequency, it is obvious that SAW sensor is superior to QCM in performance. In particular, the guided shear horizontal (SH) SAW sensor, which is also known as the Love Wave sensor, has shown its advantages in biosensor applications due to its high sensitivity and stability in the liquid phase [17][18][19] velocity. The guiding layer can not only trap acoustic energy near the sensing surface which leads to an increased sensitivity to any physical changes at the surface, but also protect the interdigitated transducers (IDTs) from the liquid environments.…”

High sensitivity cardiac troponin assays in the clinical laboratories

“…Adherence to such schedules could be obviated by continuous monitoring of cTn levels using one of the cTn sensors in development [73][74][75][76]. Even if cTn is not monitored on a continuous basis, it is nearly impossible to adhere to an exact schedule of 3-h blood draws.…”