Polarization Induced Electro-Functionalization of Pore Walls: A Contactless Technology

Abstract

This review summarizes recent advances in micro- and nanopore technologies with a focus on the functionalization of pores using a promising method named contactless electro-functionalization (CLEF). CLEF enables the localized grafting of electroactive entities onto the inner wall of a micro- or nano-sized pore in a solid-state silicon/silicon oxide membrane. A voltage or electrical current applied across the pore induces the surface functionalization by electroactive entities exclusively on the inside pore wall, which is a significant improvement over existing methods. CLEF’s mechanism is based on the polarization of a sandwich-like silicon/silicon oxide membrane, creating electronic pathways between the core silicon and the electrolyte. Correlation between numerical simulations and experiments have validated this hypothesis. CLEF-induced micro- and nanopores functionalized with antibodies or oligonucleotides were successfully used for the detection and identification of cells and are promising sensitive biosensors. This technology could soon be successfully applied to planar configurations of pores, such as restrictions in microfluidic channels.

Bipolar Electrochemiluminescence Imaging: A Way to Investigate the Passivation of Silicon Surfaces

“…Taking advantage of this approach localized addressing by an oxidation reaction of micropatterned regions of silicon was demonstrated. Interestingly, these results which benefited from ECL as a powerful technique for BPE and surface reactivity monitoring, could be implemented for other domains such as biofunctionalization of silicon chips or analysis of biomarkers, all without any direct contact of the substrate with the electrochemical supplying unit [52] . However, combining BPE with ECL imaging may present a few disadvantages that should be considered and solved to map the surface reactivity: i) polarizing small surface area or objects in the micrometer and nanometer range may require to impose very high potentials to the feeder electrodes in classic BPE open configurations; ii) ECL signal of the model [Ru(bpy) 3 ] 2+ /TPA system may vary during the ECL experiments because of the progressive lower oxidation rate of the coreactant; [53] iii) finally, in BPE experiments, oxidation rate on the anodic pole of the polarized surface or object is intrinsically linked to the reduction rate on the cathodic pole and both anodic and cathodic reactions should be considered.…”

Sensing with Nanopores and Aptamers: A Way Forward

“…In most surface functionalization, the whole surface of the nanopore membrane is covered inducing a loss in recognition specificity inside the pore for sensing applications. Interestingly, the ContactLess ElectroFunctionalization (CLEF) technique allows functionalizing with a large range of ligands (DNA, antibodies) only the inner part of the nanopore [ 118 , 119 , 120 , 121 ] which is a good strategy for enhancing the detection of protein with solid-state nanopore [ 122 ].…”

Ultrasensitive and Selective Protein Recognition with Nanobody‐Functionalized Synthetic Nanopores

“…[ 7,9,13,14 ] In contrast, the use of receptor proteins has been limited to a few model interactions, in particular, conventional antibody‐antigen combinations and streptavidin‐biotin. [ 15,16 ]…”