Electrochemical analysis of Ca2+ based on DNAzyme catalyzed degradation of DNA hydrogel

Calcium ion is a type of indispensable metal elements in biology, which participates in processes like maintaining the excitability of neuromuscular muscles. However, calcium content should be monitored in a safety range. Herein, a novel electrochemical method is developed for Ca²⁺ assay by monitoring electrochemical response after DNAzyme catalyzed DNA hydrogel degradation. Pure DNA hydrogel is first built with three-way junction scaffolds and linkers containing Ca²⁺-dependent DNAzyme sequence. In the presence of target Ca²⁺, the substrates in linkers are cleaved and DNA hydrogel can be degraded gradually. The encapsulated electrochemical species thus facilely interact with the electrode, leading to the increase of electrochemical responses. This electrochemical method for Ca²⁺ quantification is selective and sensitive, which also performs satisfactorily challenging biological samples like sweat and urine.