Size-dependent modulation of graphene oxide–aptamer interactions for an amplified fluorescence-based detection of aflatoxin B₁ with a tunable dynamic range

Abstract

Aflatoxin B1 (AFB1) is a common toxin found in many foods. While AFB1 sensors have been reported, few studies have shown amplified detection with tunable dynamic ranges. We herein report a simple and highly sensitive amplified aptamer-based fluorescent sensor for AFB1, which relies on the ability of nano-graphene oxide (GO) to protect aptamers from nuclease cleavage for amplified detection and on the nanometer size effect of GO to tune the dynamic range and sensitivity. The assay was performed by simply mixing the carboxyl-X-rhodamine (ROX)-labeled AFB1 aptamer, the GO, the nuclease, and the AFB1 samples. Modulating the size of the GO nanosheet resulted in three dynamic ranges, i.e., 12.5 to 312.5 ng mL(-1), 1.0 to 100 ng mL(-1), and 5.0 to 50 ng mL(-1), with corresponding limits of detection of 10.0 ng mL(-1), 0.35 ng mL(-1) and 15.0 ng mL(-1), respectively. The sensor was highly selective against other aflatoxins and common molecules in foods, and its performance was verified in corn samples spiked with known concentration of AFB1.

The Role of Nanotechnology in the Fortification of Plant Nutrients and Improvement of Crop Production

“…In biosensing, graphene oxide has been applied in the enhanced detection of aflatoxins in food materials [145]. Zhang et al [146] immobilized hemoglobin with silica coated gold nanorods, which act as biosensor.…”

A New Colorimetric Sensor for Cysteine Determination Based on Dual Reacting‐mediated Strategy

“…Cysteine can induce the reduction of Fe 3+ in the mild solution due to the strong reductive capability of -SH group of cysteine. [31][32][33] As expected, GO can easily form composite in water solution with phenanthroline indicator molecule through π-π stacking affinity and thus enhanced the visual signal with an amplified UV-Vis absorbance as well as with a dark orange red color. 36 Then the generated Fe 2+ in solution could selectively bind with phenanthroline molecule and resulting in an obvious color change from colorless to yellowish red within a short time as well as providing an obvious optical response of UV-Vis absorption with peak wavelength at 510 nm, which can be attributed the good coordination between phenanthroline molecule and Fe 2+ species.…”

“…Example on those assays include specific substitution reaction, 24 ions self-assembly reaction, 25 nucleophilic addition reaction, 26 charge-transfer process, 27 conjugate addition/cyclization sequence mechanism, 28 and so on. [31][32][33] Herein, due to several features such as fewer steps, simple operation and good reproducibility as well as easy to control, here, we developed a simple and rapid colorimetric sensing strategy for cysteine determination on the basis of the combination of dual reacting mediated process consisting of an analyte-induced formation of ferrous ion and a GO-supported ionic recognition behavior of phenanthroline indicator. However, several drawbacks such as insufficient long-term stability, complicated synthetic process, and unsatisfactory reproducibility are still remaining on this community.…”

Aptamer-Based Biosensor for Detection of Mycotoxins

“…The aptasensor adopted the ability of GO for aptamer protection from nuclease cleavage and used the nanometer size performance of GO to improve sensitivity. Three detection ranges (12.5-312.5, 5.0-50, and 1.0 to 100 ng mL −1 ) were achieved with a detection limit of 10.0, 15.0, and 0.35 ng mL −1 , respectively (Zhang et al, 2016a). Furthermore, a colorimetric method was carried out for AFB1 determination using the aptamer and two split DNAzyme halves.…”