Functionalization of optical nanotip arrays with an electrochemical microcantilever for multiplexed DNA detection

Abstract

Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individually and multiplexed fluorescence detection is demonstrated. Finally, remote fluorescence detection was performed by imaging through the optical fiber bundle itself after hybridisation with the complementary sequence.

Editors' Choice—A Methodology to Electrochemically Fabricate Fe-Ni-Co Nanotips

“…[20][21][22][23] The reported nanotip materials used in AFM/STM are usually W and Pt/Ir, which are prepared through a "drop off" technique, where the tungsten wire is immersed in a KOH solution (etchant) acting as an anodic electrode; the highest etching rate appears just below the air/electrolyte interface, causing necking and eventual "drop off" of the bottom part of the wire, leaving a sharp tip. 14,17,19,24,25 Alternative methods for fabricating nanotips include: focused ion beam (FIB) lithography, 26 vapor-liquidsolid method (VLS), 27,28 and a novel, self-masking technique where SiC nanosized clusters are generated on top of a substrate, followed by a dry etch of the unmasked substrate regions to create nanotips where the SiC clusters reside.…”

Multiplexed Remote SPR Detection of Biological Interactions through Optical Fiber Bundles

“…Among them, micro-contact deposition using soft microcantilevers was the most well-suited due to the technical complexity associated with the handling of the optical fiber bundle microstructured face. Previously used silicon cantilevers for optical fiber functionalization [35] did not allow a proper deposition of liquid drops onto the etched fibers used in this work as they damaged the higher aspect ratio and more fragile micropillar structures (See electronic Supplementary Materials Figure S5). Newly developed 3D-printed polymeric microcantilevers [41,42] (Figure 1 and electronic Supplementary Materials Figure S4) were soft enough to touch the apex without breaking the structures nor damaging the gold layer, and to deposit microdrops of solution with an appropriate size (see Figure 2A for the droplets' deposition plan (i), the schematic deposition principle (ii) and the images of the droplets deposition with the soft polymeric cantilever (iii, iv)).…”

“…In a recent report [32], our team has demonstrated for the first time highly-parallel remote SPR detection of DNA hybridization via a microstructured optical fiber bundle. Nevertheless, the functionalization of a non-planar surface such as this bundle presented a challenge [33][34][35][36][37][38] because of the lack of an adapted multi-functionalization process. We were able to functionalize the whole surface with a single probe and thus to detect only one DNA target.…”

Fabrication of gold-coated PDMS surfaces with arrayed triangular micro/nanopyramids for use as SERS substrates

“…Surface enhanced Raman spectroscopy (SERS) is a prominent, highly analytical tool for the detection of chemical molecules and biological species at low concentrations. SERS has recently attracted wide-ranging attention from researchers in many fields, including biosensing and bioanalysis [ 1 – 3 ], cancer cell work [ 4 ], virus identification [ 5 – 6 ], food safety [ 7 – 8 ] and gas vapor research [ 9 – 10 ]. As compared to traditional Raman scattering technology, SERS can provide significant signal amplification for analyte molecules absorbed on a SERS-active substrate and can extend the scope of Raman scattering to detect molecules at very low concentrations.…”