ssDNA‐Functionalized Nanoceria: A Redox‐Active Aptaswitch for Biomolecular Recognition

Abstract

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(-9) m 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.

Chemical and Biological Sensors for Food-Quality Monitoring and Smart Packaging

“…The sensor was applied for OTA detection in wheat in the linear range of 0.78–8.74 ng/mL and LOD of 0.07 ± 0.01 ng/mL. In another work, ceria nanoparticles functionalized with OTA-specific aptamers were used as enzyme-mimetic probes for colorimetric OTA detection [ 71 ]. OTA binding caused changes in ceria-particle reactivity, which was assessed by measuring TMB oxidation by ceria.…”

Nano-Aptasensing in Mycotoxin Analysis: Recent Updates and Progress

“…Other nanomaterials have been used in OTA aptasensing; such as nanoceria for its redox properties [ 127 ], single-walled carbon nanotubes as signal quenchers [ 128 ] or electrochemical signal amplifiers [ 129 ], nanographite as fluorescence quencher [ 130 ] and fluorescent nanoparticles. Table 1 provides analytical characteristics of literature reported nanomaterials based aptasensors for the detection of OTA ( Table 1 ).…”

Label-Free Aptasensors for the Detection of Mycotoxins

“…In addition to methods based on solid supports, label-free assays can also be performed directly in solution and are mostly coupled to optical detection.The best example of these assays are sensors based on the switchable structure of aptamers, aptamer DNAzymes and/or chemical of physical properties of nanoparticles [24]. Bulbul et al reported an optical aptasensor based on the alteration of the catalytic activity of redox active nanoceria and the conformational change of OTA aptamer upon target binding [25]. The common point of these techniques is the relationship between the measured signal and the concentration of the bound target.…”

“…By binding different aptamer concentrations with a fixed OTA concentration, the association constant of aptamer-OTA conjugate on nanoceria was calclulated as 0.120 nmol −1 . In addition, the authors have shown that the optical properties of nanoceria are conserved and enhanced after 2 days [25]. …”