A FRET based ultrasensitive fluorescent aptasensor for 6′-sialyllactose detection

As a kind of human milk oligosaccharide, 6'-sialyllactose (6'-SL) plays an important role in promoting infant brain development and improving infant immunity. The content of 6'-SL in infant formula milk powder is thus one of the important nutritional indexes. Since the lacking of efficient and rapid detection methods for 6'-SL, it is of great significance to develop specific recognition elements and establish fast and sensitive detection methods for 6'-SL. Herein, using 6'-SL specific aptamer as the recognition element, catalytic hairpin assembly as the signal amplification technology and quantum dots as the signal label, a fluorescence biosensor based on fluorescence resonance energy transfer (FRET) was constructed for ultra-sensitive detection of 6';-SL. The detection limit of this FRET-based fluorescent biosensor is 0.3 nM, and it has some outstanding characteristics such as high signal-tonoise ratio, low time-consuming, simplicity and high efficiency in the actual sample detection. Therefore, it has broad application prospect in 6'-SL detection.