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Aptamer functionalisation of back-gated graphene field effect transistors for Pb2+ sensing
* 1 , 2 , 1 , 1 , 1 , 1 , 3
1  Wolfson Nanomaterials & Devices Laboratory, School of Engineering , Computing and Mathematics, University of Plymouth, Plymouth, Devon, PL4 8AA, UK
2  Optics and Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
3  Optics and Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012
Academic Editor: Giovanna Marrazza

https://doi.org/10.3390/IECB2022-12344 (registering DOI)
Abstract:

We discuss the development of aptamer functionalised, back-gated, graphene field effect transistor (GFET) biosensors for the targeted detection of Lead (Pb2+) ions. The widespread existence of the heavy metal Pb2+ in the environment is a severe threat to the health of humans. It is a neurotoxin that accumulates over time in the body restricting the cognitive, behavioural and psychological development of children along with causing irreversible harm to the human foetus. New biosensors which allow for the rapid, sensitive and low-cost detection of Pb2+ are required to monitor this toxicant in water sources worldwide. The GFET devices were fabricated using a scalable photolithographic patterning process with evaporated Cr and sputtered Au contacts over monolayer graphene on Si/SiO2. The single stranded Thrombin Binding Aptamer (TBA) was immobilised onto the graphene channel either directly with a pyrene terminated 5’ end or indirectly using the 1-pyrenebutanoic acid succinimidyl ester (PBASE) molecule to facilitate DNA crosslinking with an amine modified 5’ end. Herein provides an evaluation of these two immobilisation strategies for the detection of Pb2+. Functionalised states were verified using Raman spectroscopy and electrically characterised using 4-probe electrical measurements to determine transfer curves allowing the calculation of field effect mobility and Dirac Point characteristics.

Keywords: Graphene; GFET; Lead; Aptamer; Thrombin Binding Aptamer (TBA); G-quadruplex;

 
 
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