ssDNA Functionalized Nanoceria: A Redox Active Aptaswitch for Biomolecular Recognition

Quantification of biomolecular binding events is a critical step for the development of biorecognition assays for diagnostics and therapeutic applications. This paper reports the design of redox active switches based on aptamer conjugated nanoceria for detection and quantification of biomolecular recognition. It is shown that the conformational transition state of the aptamer on nanoceria, combined with the redox properties of these particles can be used to create surface based structure switchable aptasensing platforms. Changes in the redox properties at the nanoceria surface upon binding of the ssDNA and its target analyte enables rapid and highly sensitive measurement of biomolecular interactions. This concept is demonstrated as a general applicable method to the colorimetric detection of DNA binding events. An example of a nanoceria aptaswitch for the colorimetric sensing of Ochratoxin A (OTA) and applicability to other targets is provided. The system can sensitively and selectivity detect as low as 0.15 × 10⁻⁹m OTA. This novel assay is simple in design and does not involve oligonucleotide labeling or elaborate nanoparticle modification steps. The proposed mechanism discovered here opens up a new way of designing optical sensing methods based on aptamer recognition. This approach can be broadly applicable to many bimolecular recognition processes and related applications.

A nanoceria based colorimetric aptaswitch for probing bimolecular recognition events is reported. The method capitalizes on a newly discovered phenomenon involving reversible, target tunable electrostatic and steric repulsion of single-stranded DNA aptamers to the surface of nanoceria. The results demonstrate that redox active nanoceria can be used as a universal platform to quantify biomolecular targets by measuring changes in the redox properties at the nanoparticle surface upon binding of the DNA and its target analyte.

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