A novel colorimetric aptasensor for ultrasensitive detection of aflatoxin M1 based on the combination of CRISPR-Cas12a, rolling circle amplification and catalytic activity of gold nanoparticles

May 12, 2021Analytica chimica acta

A new color-changing sensor for ultra-sensitive detection of aflatoxin M1 using gene-cutting enzymes, DNA amplification, and gold nanoparticles

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Abstract

A colorimetric aptasensor achieved a detection limit as low as 0.05 ng/L for aflatoxin M(AFM).

The sensor operates by utilizing CRISPR-Cas12a, rolling circle amplification, and gold nanoparticles.
In the presence of AFM, the sensor generates large single-stranded DNA structures, maintaining a yellow color.
Absence of AFM leads to the activation of CRISPR-Cas12a, resulting in a color change to colorless.
The biosensor demonstrated high selectivity for AFM in both pure and spiked milk samples.
The method is sensitive and does not require complex equipment, allowing for potential applications in detecting other mycotoxins.

AI simplified

Colorimetric approaches have received noticeable attention among sensing methods in view of simplicity and watching the color change of sample by the naked eyes. However, developing colorimetric sensing methods which show high sensitivity is still problematic. Herein, based on CRISPR-Cas12a, rolling circle amplification (RCA) and catalytic activity of gold nanoparticles (AuNPs), a colorimetric aptasensor was introduced for highly sensitive detection of aflatoxin M(AFM). In the presence of AFM, the CRISPR-Cas12a is inactivated and large single-stranded DNA (ssDNA) structures are formed on the surface of AuNPs following the addition of T4 DNA ligase and phi29 DNA polymerase. So, the sample color remains yellow after addition of 4-nitrophenol. However, no huge DNA structure is observed on the surface of AuNPs in the absence of target because of activation of CRISPR-Cas12a and digestion of primer. So, the color of sample switches to colorless. The results indicated that the biosensor had high selectivity toward AFMand the approach achieved a detection limit as low as 0.05 ng/L. In addition, it could sensitively identify AFMin the spiked milk samples. Overall, this approach is highly sensitive and does not require sophisticated equipment. Therefore, it maintains promising potential for other mycotoxins detection in real samples by simply replacing the applied sequences. 1 1 1 1 1

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A novel colorimetric aptasensor for ultrasensitive detection of aflatoxin M1 based on the combination of CRISPR-Cas12a, rolling circle amplification and catalytic activity of gold nanoparticles

Abstract

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