Fabrication of a Highly Sensitive Aptasensor for Potassium with a Nicking Endonuclease-Assisted Signal Amplification Strategy

Abstract

A novel strategy to fabricate an aptasensor for potassium with high sensitivity and selectivity by using nicking endonuclease is proposed in this work. A nicking endonuclease (Nt.CviPII), which may recognize specific nucleotide sequences in double-stranded DNA formed by a potassium-binding aptamer and a linker DNA but cleave only the linker strand, may transfer and amplify the quantitative information of the potassium detection to that of the linker DNA through elaborate strand-scission cycles. Since the technique for gene assay is much more mature, the linker DNA can thereby be detected by a number of available methods. Here, taking advantage of a simple and fast gold nanoparticles-based sensing technique, we are able to assay the linker and consequently potassium ion simply by UV-vis spectroanalysis and even with the naked eye. Results show that a 2 μL sample containing 0.1 mM of potassium is enough to induce distinct color appearance of the nanoparticles, and the potassium ion can be easily distinguished from many other ions. The strategy proposed in this work shows some unique advantages over some traditional methods and may be further developed for the detection of some other chemicals in the future.

Strategies for enhancing the sensitivity of plasmonic nanosensors

“…In the assay, a DNA sticky end pair and EcoRImodified nanoparticles were utilized because divalent Mg 2+ is a cofactor to activate EcoRI cleavage of DNA. Li et al [213] demonstrated a colorimetric aptasensor for K + using nicking endonuclease. The detection mechanism is based on the competitive binding of a potassium-specific aptamer to K + and a DNA linker.…”

Ultrasensitive electrochemical detection of avian influenza A (H7N9) virus DNA based on isothermal exponential amplification coupled with hybridization chain reaction of DNAzyme nanowires

“…The flexible base sequences, isothermal reaction and reduced nonspecific binding properties provided unique features for bioanalytical applications. Specifically, the G-quadruplex-hemin horseradish peroxidase (HRP)-mimicking enzyme has been extensively used as a catalytic label for the amplified colorimetric (Li et al, 2009;Zhu et al, 2011), electrochemical Wang et al, 2014b) or chemiluminescent (Gao and Li, 2013;Luo et al, 2012;Zhou et al, 2012) detection of DNA. By combination with hybridization chain reaction (HCR) to assemble long nanowires or rolling circle amplification strategy, G-quadruplex-hemin complex itself can achieve the signal amplification process efficiently (Cheglakov et al, 2007;Shimron et al, 2012;Wang et al, 2014a;Weizmann et al, 2006).…”

Label-Free Fluorescent Detection of Ions, Proteins, and Small Molecules Using Structure-Switching Aptamers, SYBR Gold, and Exonuclease I

“…4,5 Unlike most conventional affinity reagents (e.g., antibodies), a group of aptamers called structureswitching aptamers (SSAs) 6 can undergo target-induced conformational change, which is actually the basis of many sensing approaches including fluorescent methods, colorimetric methods, 7,8 and electrochemical methods. 9,10 Biosensing by fluorescence is one of the most popular methods for the design of aptamer-based assays, largely because of the ease of detection, good sensitivity, and potential for highthroughput analysis.…”