A miniaturized ISFET-ELISA system with a pretreated fused silica capillary as reaction cartridge

A universal ELISA-based analytical system is described, which consists of a flow-through set-up with a pretreated fused silica capillary as a reaction cartridge and an ISFET array as a detector. The reliability of the device has been tested for two different analytes: T-2 toxin and saxitoxin. For each toxin a reversible indirect competitive ELISA has been established that uses an activated fused silica capillary as a solid phase. Urease, which acts as enzyme label in the immunoassay, produces a pH-shift that can be detected by the ISFET array. Due to a preincubation step the lower detection limit is 10 pg/ml for T-2 toxin. The main advantages of the system are small sample volumes, short cycle times and an excellent stability of the regenerable receptor layer.