Target-inspired Zn-dependent DNAzyme for ultrasensitive impedimetric aptasensor based on polyacrylic acid nanogel as amplifier.

In general, the traditional impedimetric aptasensor for detecting protein is based on its high molecular weight and low dielectric constant. Yet, the efficiency of these aptasensors is hindered by the slight resistance change in the trace concentration range because of the high initial resistance (the electrostatic repulsion between the compact negatively charged DNA on the electrode and [Fe(CN)]). To effectively and simply circumvent this issue and improve the detection sensitivity, we design an impedimetric aptasensor by reducing the substrate DNA's density on the electrode through the target-inspired recycling DNA cleavage.

Ultrasensitive detection of prostate specific antigen by electrochemical aptasensor using enzyme-free recycling amplification via target-induced catalytic hairpin assembly.

Based on the target-induced catalytic hairpin assembly and bimetallic catalyst, the enzyme-free recycling amplification strategy for sensitive detection of prostate specific antigen (PSA) has been designed. The aptamer and its complementary DNA (C-apt) are modified on the magnetic particles. The aptamer-PSA binding event can release the C-apt that triggers the catalytic assembly between hairpin capture DNA and hairpin help DNA.

Nanoprobe-Enhanced, Split Aptamer-Based Electrochemical Sandwich Assay for Ultrasensitive Detection of Small Molecules.

It is quite challenging to improve the binding affinity of antismall molecule aptamers. We report that the binding affinity of anticocaine split aptamer pairs improved by up to 66-fold by gold nanoparticles (AuNP)-attached aptamers due to the substantially increased local concentration of aptamers and multiple and simultaneous ligand interactions. The significantly improved binding affinity enables the detection of small molecule targets with unprecedented sensitivity, as demonstrated in nanoprobe-enhanced split aptamer-based electrochemical sandwich assays (NE-SAESA).