A sensing smartphone and its portable accessory for on-site rapid biochemical detection of marine toxins

Okadaic acid (OA) and saxitoxin (STX) are common marine toxins which can accumulate in shellfish and affect human health through the food chain. A convenient and efficient method is urgently required to perform on-site detection of marine toxins to avoid frequent poisoning incidents. In this work, a smartphone-based system cooperating with competitive immunoassay strips was designed for rapid on-site detection of OA and STX. The smartphone was employed as a light detector for image acquisition and data processing. The 3D-printed portable accessory of the smartphone was utilized to fix the test strips. The homemade APP – iStrip used the pixel scan to obtain the valley value of the pixel curve as the output of the strip. The strip analytical method was easy to operate with a detection limit of 2.800 ng ml−1 for OA and 9.808 ng ml−1 for STX. Moreover, with the optimization of the antigen–antibody ratio on the strip, it provided quantitative analysis of OA and STX in the range of 3–20 ng ml−1 and 10–100 ng ml−1, respectively. Taking advantage of the smartphone and biochemical analysis, the strip analytical system will be a promising tool for on-site rapid detection of these two toxins.