A competitive aptamer chemiluminescence assay for ochratoxin A using a single silica photonic crystal microsphere

We designed a competitive aptamer chemiluminescence assay for ochratoxin A (OTA) on the surface of a single silica photonic crystal microsphere (SPCM) in cereal samples. The structural color of SPCMs is used to recognize and trace the microspheres during process of detection. Anti-aptamer was immobilized on the surface of SPCM. OTA and anti-aptamer competed to bind to aptamer when OTA and its aptamer (labeled by biotin at 5′end) were added in the system. The chemiluminescence signal was developed by the horseradish peroxidase (HRP), luminol and H2O2. The molecules on the single SPCM can produce enough chemiluminescence signal intensity for quantitative detection for OTA. The linear detection range for OTA was from 1 pg/mL to 1 ng/mL and recovery rates were 89%-95%, 81%-92% and 94%-105% in rice, wheat and corn, respectively. The results showed that the developed method for OTA using a single SPCM has a great application potential in cereal samples.