An electrochemical DNA sensor without electrode pre-modification

Abstract

We present a non-modification electrochemical DNA sensing strategy, which used Potential-Assisted Au-S Deposition and a clamp-like DNA probe. The dual-hairpin probe DNA was tagged with a methylene blue (MB) at the 3' terminal and a thiol at the 5' terminal., Without being hybridized with target DNA, the loop of probe prevented the thiol from reaching the bare gold electrode surface with an applied potential., After hybridization with the target DNA, the probe' s loop-stem structure opened through two distinct and sequential events, which led to the formation of a triplex DNA structure. Then the thiol easily contacted with electrode and resulted in potential-assisted Au-S self-assembly. Electrochemical signals of MB were measured by differential pulse voltammetry (DPV) and used for target quantitative detection. This strategy offered a detection limit down to 2.3pM. and an inherently high specificity for detecting even single mismatch.

Specific Coordination between Zr-MOF and Phosphate-Terminated DNA Coupled with Strand Displacement for the Construction of Reusable and Ultrasensitive Aptasensor

“…In the combination of the aptamer with electrochemical analysis technology, the electrochemical aptasensors are highly selective and have excellent sensitivity and ease of operation, thus attracting considerable attentions in the past decade. − In a typical electrochemical aptasensor, the aptamer is immobilized on the surface of an electrode and the biorecognition between the aptamer and target induces the readable electrochemical signals for analysis. , Unfortunately, the classic electrochemical aptasensors have some defects. For example, the aptamer is usually single-point labeled with an electroactive molecule, such as methylene blue (MB) , and ferrocene (Fc), , resulting in limited signal output as well as low sensitivity. In addition, although the reusability of the aptasensors has been realized on the microfluidic electrochemical sensors, , the normal electrochemical aptasensors are still feeble in reusability because of the strong affinity between aptamer and the targets .…”

Improved Microbial Fuel Cell Performance by Engineering E. coli for Enhanced Affinity to Gold

“…A base strain (no cys, no P2X) expressed the eCPX scaffold but received no additional engineering to promote affinity towards gold. We had previously created a strain in which the N-terminal end residue was modified to cysteine [44], which is useful here as SH moieties are frequently used for surface attachment in gold-based electrochemical systems [51,52]. Gold-binding peptides were inserted at both termini.…”

A review of microfabricated electrochemical biosensors for DNA detection

“…Examples of sensitive DNA detection systems involving this approach include detection of plant pathogen DNA using isothermal amplification in combination with a gold nanoparticle reporter, detection of DNA sequences relevant to Mycobacterium Tuberculosis using a gold surface functionalized with thiol modified DNA sequences, and E.coli DNA detection using a graphene oxide-chitosan composite decorated with nickel ferrite nanoparticles to achieve 10 -16 M sensitivity (Gaffar et al, 2017;Lau and Botella, 2017;Tiwari et al, 2015). DPV has been used to achieve 2.3 pM sensitivity for DNA hybridization when a methylene blue tagged hairpin probe DNA film was immobilized using assisted potential deposition and in similar work a LoD of 3.4 pM was discovered for a ferrocene tagged DNA probe deployed in a similar configuration (Hong et al, 2017;Kong et al, 2018). Finally, simultaneous detection of Legionella and Legionella pneumophila was achieved by using a signal-off double DNA probe electrochemical sensor with ferrocene and methylene blue hairpin probes where signal changes arise through specific cleavage of restriction sites within the probe sequences .…”