Aptasensing biosynthesized phosphatidylserine with a AuNPs nanozyme-based colorimetric aptasensor

Sensitive monitoring of the target products during the biosynthesis process is crucial,and facile analytical approaches are urgently needed.Herein,phosphatidylserine(PS)was chosen as the model target,a colorimetric aptasensor was developed for the rapid quantitation in biosynthesis samples.A chimeric aptamer was constructed with two homogeneous original PS aptamers.Specific recognition between the chimeric aptamer and PS results in the desorption of aptamer from the surface of the AuNPs nanozyme,and the peroxidase-like enzymatic activity of the AuNPs nanozyme was weakened in a relationship with the different concentrations.The developed aptasensor performed well when applied for analyzing PS in biosynthesis samples.The aptasensor offers good sensitivity and selectivity,under optimal conditions,achieving monitoring and quantitation of PS in the range of 2.5-80.0μmol/L,with a limit of detection at 536.2 nmol/L.Moreover,the aptasensor provides good accuracy,with comparison rates of 98.17%-106.40%,when compared with the HPLC-ELSD.This study provides a good reference for monitoring other biosynthesized products and promoting the development of aptamers and aptasensors in real-world applications.

Development of a Label-Free Colorimetric Aptasensor with Rationally Utilized Aptamer for Rapid Detection of Okadaic Acid

Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis.In this study,a label-free col-orimetric aptasensor was constructed for visual and rapid detection of OA in shellfish.To exploit the binding capability of the anti-OA aptamer,the inherent molecular recognition mechanism of aptamer and OA was studied,based on molecular docking,fluorescent assay,and biolayer interferometry.Consistent results showed that the stem-loop near the 3’terminal of the aptamer exhibit dominate binding capacity.Based on the revealed recognition information,the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride(PDDA)for the development of the label-free colorimetric aptasensor,in which the 3’terminal was thoroughly exposed to OA.The aptasensor provided robust performance with a linear detection range of 100-1200 nmol L-1,a limit of detection of 41.30 nmol L-1,recovery rates of 91.6%-106.2%,as well as a high selectivity towards OA in shellfish samples.The whole detection process can be completed within 1 h.To our best knowledge,this is the first time that the anti-OA aptamer was thoroughly studied,and a label-free colorimetric aptasensor was rationally designed in this way.This study not only provides a rapid detection method for highly sensitive and specific detection of OA,but also serves as a reference for the design of efficient aptasensors in the future.

A Label-Free Colorimetric Aptasensor Containing DNA Triplex Molecular Switch and AuNP Nanozyme for Highly Sensitive Detection of Saxitoxin

Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.

A simple AuNPs-based colorimetric aptasensor for chlorpyrifos detection

In this work, a simple gold nanoparticles(Au NPs) based colorimetric biosensor was developed for chlorpyrifos(Chl) detection using an aptamer as the capture probe. The Chl-aptamer with low dissociation constant(Kd) of 58.59 ± 6.08 nmol/L was selected by ss DNA library immobilized systematic evolution of ligands by enrichment(SELEX). In the absence of Chl, the Chl-aptamer acted as the stabilizer for Au NPs in salt solution. In the presence of Chl, the highly specific Chl-aptamer bound with Chl targets immediately,thus a self-aggregation of Au NPs induced by salt was displayed. The fabricated colorimetric aptasensor exhibited an excellent sensitivity for Chl detection with the LOD as low as 14.46 nmol/L. In addition, the aptasensor was applied to test Chl in tap water, cucumber and cabbage samples, the excellent recoveries with acceptable RSD values below 5% demonstrated that the method can be considered as a promising tool for simple, rapid Chl detection.