Highly stable colorimetric aptamer sensors for detection of ochratoxin A through optimizing the sequence with the covalent conjugation of hemin

Optimization of hairpin DNA is introduced to detect ochratoxin A (OTA) by chemically conjugating its cofactor, hemin, toward the 5'-end. The newly designed OTA aptasensor showed enhanced stability and sensitivity, thereby lowering the detection limit to an similar to 1 nM level. Furthermore, an optimal spacer for hemin conjugation was investigated for stable responses toward very diluted OTA solutions.