Redox-labelled electrochemical aptasensors with nanosupported cancer cells

Ballistic Brownian motion of nanoconfined DNA

“…Finally, the energetics of nanoconfined DNA (thermal conductivity and dissipation) will be explored. Inertia could be at the origin of the reduced DNA melting temperature reported under nanoconfinement 40,41 , which has for example been exploited to stabilize aptamers in their optimum configuration for cancer cells detection 41 . As the replication process, which operates in nanocavities of a few nanometers wide and about 14-17 bp opened loop 42 , is considered to be responsible for a substantial fraction of energy consumption in cells, e.g., for prokaryotes, 13% of 6 and Supplementary Discussion 2. c, <τup> -1 and <τdown> -1 as a function of zgap obtained from dT20 MD tracks with a threshold ε = 0.3 ± 0.1 nm that determines error bars (see Supplementary Fig.…”

Electrochemical response of surface-attached redox DNA governed by low activation energy electron transfer kinetics

“…The versatility of E-DNA sensors stems from the ability of oligonucleotides to specifically recognize many different analytes, including complementary DNA strands, 1 small molecules, 6 proteins, 7 viruses, 8 or even living cells. 9,10 To optimize their sensitivity, it is of utmost importance to understand their signaling mechanism.…”

Single-cell Electrochemical Aptasensor Array

“…The key advantages of this technology are not only to suppress the false positive signal arising from the pressure exerted by all (including non-target) cells pushing on the aptamers by downward force, but also to stabilize the aptamer at the ideal hairpin configuration thanks to a confinement effect. 26 With the first implementation of this technique, a LOD of 13 cells (with 5.4 μL of cell suspension) was estimated.…”

“…Figure 1 shows a simple description of the operation of this single-cell EC aptasensor and the configuration of the proposed microfluidic system. The device is assembled on micrometric gold working electrodes; an active biorecognition monolayer, composed of tethered ferrocene (Fc)-labelled ssDNA SYL3C aptamers 24, 25 immobilized on the gold surfaces for the efficient and specific recognition of the epithelial cell adhesion molecules (EpCAMs), and the backfilling of oligoethylene glycol (OEG) molecules for mitigating nonspecific adsorption and stabilizing aptamers; a regular array of hydrogen-silsesquioxane (HSQ) nanopillars fabricated by high-speed e-beam lithography, 26, 28, 29 and SU-8 microwells for gravitationally trapping single-cell (the optical image and dimensions of the SU-8 microwells are shown in Figure S1). A simple description of the fabrication process is depicted in Figure 1c (more details are depicted in Figure S2).…”

“…The choice of the dimensions of HSQ nanopillars was discussed in the previous work. 26 The atomic force microscopy (AFM) image shown in Figure 1d presents the HSQ nanopillars with a diameter of 200 nm, a height of 19.7 nm, pitch of 500 nm (a larger scale of the AFM of HSQ nanopillars that are well aligned on the Au microelectrode is shown in Figure S3); this configuration aimed to keep the cell at a distance Z gap of a few nanometers above the sensor surface, which is small enough to enable an interaction between the SYL3C aptamers and EpCAMs (Figure 1b), this Z gap has been estimated to be around 5 nm, upon consideration of cells deformation.…”