Electrochemical flow enzyme immunoassay by means of a needle-shaped sampler/reactor.

A needle-shaped sampler/reactor was developed for an electrochemical enzyme immunoassay with the direct sampling of living sample blood. This device was evaluated using IgG determination chemistry. Antibodies were immobilized on an inner wall of the sampler/reactor. Incubation for the enzyme reaction was not needed because this reactor was very small (250 microm in diameter). The analysis was conducted within 15 min in the simplest protocol including the reactor refreshment. The limit of detection was 3 pg, and 20 attomol in the most sensitive protocol. Furthermore, the sampling of a solution contained in an agar block and a whole-blood analysis were demonstrated.