Click chemistry-assisted self-assembly of DNA aptamer on gold nanoparticles-modified screen-printed carbon electrodes for label-free electrochemical aptasensor

Aptamer-Based Electrochemical Sensing of Lysozyme

“…Next to these approaches, in recent years, a few aptamer-based analytical methods have been developed towards lysozyme recognition and detection [47,[55][56][57][58][59][60][61][62][63]. Aptamers are small single-stranded oligonucleotides (DNA or RNA) that are selected in vitro to bind with high affinity and specificity any selected target of choice, from small-sized, such as metal ions [64], to large ones, such as cells [65].…”

“…Efficient blocking of nonspecific adsorption is typically performed by incubation of Au-based aptasensors with short hydroxylated thiols, such as 6-mercapto-1-hexanol [60,87,90], while, for carbon-based interfaces, blocking with 0.1%-1% solutions of BSA [44,63,88] or IgG [81] is preferred. Moreover, a washing step with buffer (sometimes containing 1% Tween-20, [87,95]) performed after incubation of the aptasensor with the sample solution further alleviates problems due to non-specific binding [44,46,60]. To ensure reliable and quantitative determination of lysozyme in real samples, the simplest approach is to dilute samples with suitable electrolyte buffer in order to match the linear range of the aptasensor.…”

“…By using click chemistry (Strategy D), Xie et al used AuNPs electrodeposited on screen-printed graphite electrodes and modified with a self-assembled monolayer of 10-azidodecane-1-thiol [60], to form a "clickable" interface with alkyne-terminated lysozyme aptamers (see Figure 3A). Compared to direct immobilization of thiolated aptamers on the AuNPs-coated electrode, this approach allowed a 3.4-fold increase in the analytical signal for a concentration of 10 pg/mL lysozyme, so increasing the sensitivity of the sensor.…”

“…Compared to direct immobilization of thiolated aptamers on the AuNPs-coated electrode, this approach allowed a 3.4-fold increase in the analytical signal for a concentration of 10 pg/mL lysozyme, so increasing the sensitivity of the sensor. The higher aptamer coverage (3.3ˆ10 11 molecules cm´2 for aptamer "clicked" on SAM versus 2.2ˆ10 11 molecules cm´2 for simple chemisorption of thiolated aptamer) was claimed to be the origin of the improved performances [60]. The potential of the "clickable" interface as generic support for an aptasensor array was further illustrated by efficient immobilization of three different aptamers (for lysozyme, cocaine and thrombin) [60].…”

“…The higher aptamer coverage (3.3ˆ10 11 molecules cm´2 for aptamer "clicked" on SAM versus 2.2ˆ10 11 molecules cm´2 for simple chemisorption of thiolated aptamer) was claimed to be the origin of the improved performances [60]. The potential of the "clickable" interface as generic support for an aptasensor array was further illustrated by efficient immobilization of three different aptamers (for lysozyme, cocaine and thrombin) [60]. More recently, electrodes modified with a TiO 2 /3D graphene/polypyrrole nanocomposite [74] proved to be an interesting alternative for lysozyme sensing.…”