A label-free aptasensor for the sensitive and specific detection of cocaine using supramolecular aptamer fragments/target complex by electrochemical impedance spectroscopy.

A simple and label-free aptasensor for sensitive and specific detection of cocaine was developed by measuring the change in electrochemical impedance spectra (EIS), based on the formation of a supramolecular aptamer fragments/substrate complex. An anticocaine aptamer was divided into two fragments, Cx and Cy. Three different sensing interfaces, called Au/Cx5S/MCE, Au/Cy3S/MCE and Au/Cy5S/MCE, were fabricated by immobilizing Cx or Cy on a gold electrode through modifying their 5' or 3' end with a thiolated group followed by the treatment with mercaptoethanol (MCE). The formation of the corresponding supramolecular aptamer fragments/cocaine complex was investigated via monitoring electrochemical impedance spectra in the presence of [Fe(CN)(6)](3-/4-). The interfacial electron transfer resistance (R(et)) was found to depend strongly on the cocaine concentration. Since the supramolecular aptamer fragments/cocaine complex was formed on the electrode surface, the sensing interface strongly affected the sensitivity of the aptasensor. Au/Cx5S/MCE was shown to have good sensitivity within a cocaine detection range of 0.1-20 μM. Moreover, MCE was shown to improve the sensitivity of the aptasensor greatly. Even without the help of amplification or labeling, cocaine concentrations as low as 100 nM could be easily detected by the impedimetric aptasensor developed. The specificity and regeneration of the cocaine aptasensor were also investigated and satisfactory results were obtained. The developed aptasensor was successfully applied to detect the cocaine in biological fluids.

Zhang DW ，Zhang FT ，Cui YR ，Deng QP ，Krause S ，Zhou YL ，Zhang XX ... -  《-》

Impedimetric aptasensor with femtomolar sensitivity based on the enlargement of surface-charged gold nanoparticles.

Deng C ，Chen J ，Nie Z ，Wang M ，Chu X ，Chen X ，Xiao X ，Lei C ，Yao S ... -  《-》

Label-free and sensitive faradic impedance aptasensor for the determination of lysozyme based on target-induced aptamer displacement.

Peng Y ，Zhang D ，Li Y ，Qi H ，Gao Q ，Zhang C ... -  《-》

Electrochemical impedance spectroscopy detection of lysozyme based on electrodeposited gold nanoparticles.

A simple, highly sensitive, and label-free electrochemical impedance spectroscopy (EIS) aptasensor based on an anti-lysozyme-aptamer as a molecular recognition element, was developed for the detection of lysozyme. Improvement in sensitivity was achieved by utilizing gold nanoparticles (AuNPs), which were electrodeposited onto the surface of a gold electrode, as a platform for immobilization of the aptamer. To quantify the amount of lysozyme, changes in the interfacial electron transfer resistance (R(et)) of the aptasensor were monitored using the redox couple of an [Fe(CN)(6)](3-/4-) probe. The R(et) increased with lysozyme concentration. The plot of R(et) against the logarithm of lysozyme concentration is linear over the range from 0.1 pM to 500 pM with a detection limit of 0.01 pM. The aptasensor also showed good selectivity for lysozyme without being affected by the presence of other proteins.

Chen Z ，Li L ，Zhao H ，Guo L ，Mu X ... -  《-》

Amplified electrochemical aptasensor taking AuNPs based sandwich sensing platform as a model.

Li B ，Wang Y ，Wei H ，Dong S ... -  《BIOSENSORS & BIOELECTRONICS》