RESUMEN
The realization of biomolecular detection assays for diagnostic purposes is technologically very challenging because such tests demand full integration for ease of use and need to deliver a high analytical performance with cost-effective use of materials. In this article an optomagnetic immunoassay technology is described based on nanoparticles that are magnetically actuated and optically detected in a stationary sample fluid. The dynamic control of nanoparticles by magnetic fields impacts the key immunoassay process steps, giving unprecedented speed, assay control and seamless integration of the total test. The optical detection yields sensitive and multiplexed assays in a low-cost disposable cartridge. We demonstrate that the optomagnetic technology enables high-sensitivity one-step assays in blood serum/plasma and whole saliva. Drugs of abuse are detected at sub-nanogram per millilitre levels in a total assay time of 1 min, and the cardiac marker troponin I is detected at sub-picomole per litre concentrations in a few minutes. The optomagnetic technology is fundamentally suited for high-performance integrated testing and is expected to open a new paradigm in biosensing.
Asunto(s)
Técnicas Biosensibles/métodos , Inmunoensayo/métodos , Magnetismo , Nanopartículas , Animales , Técnicas Biosensibles/economía , Técnicas Biosensibles/instrumentación , Bovinos , Drogas Ilícitas/análisis , Drogas Ilícitas/metabolismo , Inmunoensayo/economía , Inmunoensayo/instrumentación , Fenómenos Ópticos , Saliva/química , Albúmina Sérica Bovina/metabolismo , Factores de Tiempo , Troponina I/sangreRESUMEN
A compact biosensor platform with giant magneto-resistive (GMR) sensors suited for the detection of superparamagnetic nanoparticle labels is presented. The platform consist of disposable biosensor cartridges and an electronic reader, which enables quantitative detection with high analytical performance, combined with robustness, ease of use and at low cost. In order to optimise the signal-to-noise ratio (SNR), magnetic labels are excited at high frequency. Wires, integrated in the silicon of the sensor chip are used to generate a well-defined magnetic field on the sensor surface, thus removing the need for mechanical alignment with external apparatus. A signal modulation scheme is applied to obtain optimal detection accuracy. The platform is scalable and can be adapted according to application-specific requirements. Experimental results indicate that three beads of 300 nm diameter can be detected on a sensor surface of 1500 microm2 for a measurement time of 1s.