Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors
Author(s)
Type
Journal Article
Abstract
An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT) and further passivated with 1-mercapto-6-hexanol (MCH). HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS), the aptasensor is able to detect human thrombin as variations in charge transfer resistance (Rct) upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA) solution, no changes in the Rct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM) layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days in different buffers and atmospheric conditions. Aptasensors based on ternary SAM layers are highly promising for clinical applications for detection of a range of proteins in real biological samples.
Date Issued
2015-09-29
Date Acceptance
2015-09-18
Citation
Sensors, 2015, 15 (10), pp.25015-25032
ISSN
1424-8239
Publisher
MDPI AG
Start Page
25015
End Page
25032
Journal / Book Title
Sensors
Volume
15
Issue
10
Copyright Statement
This is an open access article distributed under the Creative Commons Attribution License (CC BY 4.0).
License URL
Subjects
DNA aptamers
Thrombin
antifouling
biosensor
electrochemical detection
screen printed electrodes
self-assembled monolayers
Aptamers, Nucleotide
Biofouling
Biosensing Techniques
Electric Impedance
Electrochemical Techniques
Electrodes
Hexanols
Humans
Serum Albumin, Bovine
Sulfhydryl Compounds
Analytical Chemistry
0301 Analytical Chemistry
0906 Electrical And Electronic Engineering
Publication Status
Published