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Impedance Biosensing atop MoS 2 Thin Films with Mo−S Bond Formation to Antibody Fragments Created by Disulphide Bond Reduction
Author(s) -
Giang Hannah,
Pali Madhavi,
Fan Li,
Suni Ian I.
Publication year - 2019
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201800845
Subject(s) - phosphine , dielectric spectroscopy , detection limit , annealing (glass) , materials science , thin film , doping , tcep , molybdenum disulfide , electrochemistry , analytical chemistry (journal) , chemistry , nanotechnology , catalysis , electrode , optoelectronics , organic chemistry , chromatography , metallurgy
Immobilization of antibody fragments to 3‐phenoxybenzoic acid (3‐PBA), which are created by disulphide bond (S−S) reduction with tris (2‐carboxyethyl) phosphine (TCEP), is reported atop MoS 2 and Cu‐doped MoS 2 thin films. MoS 2 and Cu‐doped MoS 2 thin films are electrodeposited using previously reported methods and tested for their ability to immobilize antibody fragments, before and after annealing in Ar at 500 °C for 3 h. This annealing procedure removes excess sulphur in the as‐deposited films, and creates coordinatively unsaturated Mo sites that are highly reactive towards sulphur, as previously reported for MoS 2 hydrodesulphurization catalysts. As demonstrated by electrochemical impedance spectroscopy (EIS) measurements, both annealed MoS 2 and Cu‐doped MoS 2 thin films adsorb antibody fragments through Mo−S bond formation, unlike the as‐deposited films. Impedance detection of 3‐PBA is reported utilizing antibody fragments bound to both materials, with a sensitivity of 2.7×10 8 Ω cm 2 M −1 and a detection limit of 2.5×10 −6 M atop MoS 2 , and a sensitivity of 5.9×10 8 Ω cm 2 M −1 and a detection limit of 3.8×10 −6 M atop Cu‐doped MoS 2 . The rms surface roughness obtained by atomic force microscopy (AFM) measurements atop annealed MoS 2 and Cu‐doped MoS 2 ranges from 60–140 nm, so the methods described herein are not limited to ultra‐smooth substrates.