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 20-hydroxyl group of ribose to 20-flouro in all
pyrimidines indicated in lowercase in 35-mer aptamer (50 GGA Acc GGu GcG cAu AAc cAc cuc AGu
GcG AGc AA 30). 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 lg/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.