Immobilization-Free Photoelectrochemical Aptasensor for Atrazine Based on Bifunctional Graphene Signal Amplification and a Controllable Sulfhydryl-Assembled BiOBr/Ag NP Microinterface

Abstract

Immobilization-free sensors (IFSs), with no requirement of fixing the recognition element to the electrode surface, have received increasing attention due to their unique advantages of reusable electrodes, not being limited by the load of the recognition element, and not being easily changed to the structure of the probe. In the present work, an effective visible light-driven immobilization-free photoelectric aptasensor for ultrasensitive detection of atrazine (ATZ) was proposed based on a reusable BiOBr/Ag NP substrate electrode with ultrafast charge transfer. Controllable thiols were used as conditioning agents for the photoelectric signal. The ingeniously designed bifunctional graphene can act as not only a molecular "bridge" for the ATZ aptamer through a strong π−π stacking effect, obtaining a graphene−aptamer complex, serving as a homogeneous recognition element, but also a switch for signal modulation for quantitative detection of target substances. Benefiting from the synergistic effect of the abovementioned factors, the proposed sensor is capable of ultrasensitive and highly selective detection of ATZ in real water samples with a low detection limit of 1.2 pM and a wide linear range from 5.0 pM to 10.0 nM. Furthermore, it shows high stability, good selectivity, and strong anti-interference ability. Thus, this work has provided a fresh perspective for designing advanced immobilization-free photoelectric sensors and convenient detection of environmental pollutants.

Extremozyme-Based Biosensors for Environmental Pollution Monitoring: Recent Developments

“…The detection of atrazine at trace levels down to 5 × 10 −12 M is achieved by time-resolved fluorescence, while higher concentrations are detected by amperometry. By comparison, one of the most sensitive aptasensors developed so far has an LOD of 1.2 × 10 −12 M [ 231 ].…”

Portable and Flexible Hydrogel Sensor for On-Site Atrazine Assay on Agricultural Products

“…Herbicides, attributed to their low price and high efficacy in weed control, , have been extensively used to improve the agricultural productivity in the world, but the abuse of herbicides incurs growing safety hazard to the environment and human health. For instance, atrazine (2-chloro-4-ethylamino-6-isopropylamino-strazine, ATZ), one of the most widely used triazine herbicide, is a selective pre-emergence or postemergence herbicide that is used to control broadleaf weeds and some gramineous weeds by inhibiting photocooperation in susceptible plants. , It has been considered to be a persistent pollutant in farmland soil, mature agricultural products, and groundwater due to its widespread application, long half-life, poor biodegradability, and apparent mobility . Studies have shown that ATZ is potentially toxic to the growth, development, reproduction, and immunity of organisms .…”

Enhanced Label-Free Photoelectrochemical Strategy for Pollutant Detection: Using Surface Oxygen Vacancies-Enriched BiVO4 Photoanode

“…on the sensing electrode surface . However, the immobilization of biological elements usually makes it difficult to detect real samples in harsh conditions such as high ionic strength and high pH . At the same time, since PEC sensors require light illumination to excite the photoelectric signals, the high-energy optical radiation can also easily lead to the denaturation of the biorecognition elements, which affects their stability. , …”