Highly sensitive biosensor based on aptamer and hybridization chain reaction for detection of cadmium ions

In this work, a highly sensitive biosensor for detecting cadmium ions (Cd²⁺) was developed based on a Cd²⁺-specific DNA aptamer and a hybridization chain reaction (HCR). The Cd²⁺ aptamer (named S0) was used to recognize Cd²⁺ and trigger the HCR. Without Cd²⁺, S0 initiated the HCR to form long nicked dsDNA structures to quench the fluorescence. Then, Cd²⁺ could bind with S0 to block HCR to recover fluorescence. This biosensor had high sensitivity with a detection limit of 0.36 nM and a linear range from 0 to 10 nM. Moreover, it showed a satisfactory selectivity and recovery rates.