Nano RNA aptamer wire for analysis of vitamin B12

A simple and stable RNA aptamer-based colorimetric sensor for the detection of vitamin B12 using gold nanoparticles (AuNPs) has been proposed. Vitamin B12 belongs to the B vitamin group and prevents pernicious anemia, which is caused by vitamin B12 deficiency. A highly stable RNA aptamer that binds to vitamin B12 was employed by structural modification of 2′-hydroxyl group of ribose to 2′-flouro in all pyrimidines indicated in lowercase in 35-mer aptamer (5′ GGA Acc GGu GcG cAu AAc cAc cuc AGu GcG AGc AA 3′). Aggregation of AuNPs was specifically induced by desorption of the vitamin B12 binding RNA aptamer from the surface of AuNPs as a result of the aptamer–target interaction, leading to the color change from red to purple. The level of detection of vitamin B12 was 0.1 μg/ml by successful optimization of the amount of the aptamer, AuNPs, salts, and stability of the aptamer. Analysis of vitamin B12 was carried out, and the observed recovery was 92 to 95.3% with a relative standard deviation in the range of 2.08 to 8.27%. The results obtained were compared with those of the ultraviolet–visible (UV–vis) spectrometry method. This colorimetric aptasensor is advantageous for on-site detection with the naked eye.