Nanotetrahedron-assisted electrochemical aptasensor with cooperatively-folding aptamer chimera for sensitive and selective detection of lysozyme in red wines.

Although aptamers show great potential in the field of analytical chemistry, their intrinsic shortcomings of relatively weak affinity and selectivity in complex working environment limit their applicability to real analysis, because the flexibility of aptamers makes the specific aptatopes (i.e., binding sites for targets) in the conformational structure unstable and deficient. Herein, an anti-lysozyme aptamer and lysozyme were chosen as models. An aptamer chimera which could cooperatively fold to provide stable aptatopes for lysozyme was designed for improvement of the anti-lysozyme aptamers' recognition ability, and an electrochemical aptasensor was then developed based on the aptamer chimera, with assistance of a rigid DNA nanotetrahedron as a spacer to orientate the aptamer chimera on the electrodes. The nanotetrahedron-aptamer chimera-based aptasensor presented highly sensitive and selective detection towards lysozyme in red wines, furnishing a 42-fold lower LOD (17.9 pmol L) and better selectivity than that of the aptasensor with the original aptamer. Moreover, the developed aptasensor was characterized by good recovery (91.3-109.0%), good accuracy, repeatability and stability, indicating the excellent practical applicability of the cooperatively-folding aptamer chimera in real world. This proof-of-concept study can be referred for any other aptamers, analytes, and samples.