Probing molecular interactions on carbon nanotube surfaces using surface plasmon resonance sensors

Abstract

In this work, we present a method to probe molecular interactions on single-walled carbon nanotube (SWNT) surfaces using a surface plasmon sensor. SWNT networks were synthesized by chemical vapor deposition and transfer-printed on gold surfaces. We studied the excitation of surface plasmon-polaritons on nanotube coated gold surfaces with sub-monolayer, monolayer, and multilayer surface coverage. Integrating the fabricated sensor with a microfluidic device, we were able to obtain binding dynamics of a bovine serum albumin (BSA) protein on SWNT networks with various tube densities. The results reveal the kinetic parameters for nonspecific binding of BSA on SWNT coated surfaces having various tube densities.

Photosensitive Field‐Effect Transistors Made from Semiconducting Carbon Nanotubes and Non‐Covalently Attached Gold Nanoparticles

“…Reflecting the literature, Mahjouri‐Samani et al reported response curves composed of a fast time component (25 ms plasmonically enhanced; 100 ms CNT‐only) and a slow time component (≈400 ms) . Here, our achieved response times of t 0 ≈ (9 ± 4) s (according to a cursory evaluation of Figure B–D) fall short of the lithographically achieved plasmonic SWNCT sensors from the literature but are in the same order of magnitude with the response times reported for sensors made likewise from CNT‐based nanoconjugates with metal nanoparticles discussed above (see Supporting Information, Section S0.1, Table SI).…”

“…According to Guldi and co‐workers, the electrical photoresponse of such nanoconjugate‐based CNT‐FET devices can be explained by the fact that photoexcitation in the receptive part of the nanoconjugate incurs a rapid charge separation inside which causes a reduction of the electron‐accepting SWCNT and, simultaneously, the oxidation of the electron‐donating moiety . The electronic transport in such a hybrid device is hence modulated when the gate field is locally perturbated, for example, by stimulation of a plasmonic response . Hence, further environmental modulations to the latter such as molecular adsorption on the plasmonically active metal nanostructure can be an origin for further modulations of the electrical signal .…”

“…Enhancement of Raman signals of Au nanoparticles is seen by the SPPs of a metallic CNT as the localized SPPs of the Au nanoparticle couple to the SPPs of CNTs . A literature review on sensor concepts for CNT nanoconjugates from literature including their nanoelectronic or optoplasmonic working principles is presented in the Supporting Information, Section S0.1. Key finding for our work was the fact that, especially for optoplasmonic gas sensing applications, integration times of minutes are reported, with 100 s used as a standard.…”

Enhancing the Colloidal Stability and Electrical Conductivity of Single-Walled Carbon Nanotubes Dispersed in Water

“…There is also no order to the surface area coverage of BSA on the nanotubes . BSA with NaCl is assumed to increase the ionic strength, but reduce the electrostatic interaction, between adjacent BSA molecules due to the screening effect of Na + and Cl − ions acting as counter and coions.…”

“…There is also no order to the surface area coverage of BSA on the nanotubes. [ 94,95 ] BSA with NaCl is assumed to increase the ionic strength, but reduce the electrostatic interaction, between adjacent BSA molecules due to the screening effect of Na + and Cl − ions acting as counter and coions. This effect in turn changes the charge distribution across the contact surface, and thus, the SWNT surface area coverage reduces.…”