Biomedical Engineering Reference
In-Depth Information
4
Conducting Polymer Nanowire-Based BioFET for
Label-Free Detection
Adam K. Wanekaya, Wilfred Chen, Nosang V. Myung, and Ashok Mulchandani
CONTENTS
4.1 Introduction ......................................................................................................................133
4.1.1 Scope and Overview of the Chapter ................................................................134
4.2 Fabrication of One-Dimensional Conducting Polymer Nanostructures ..................135
4.2.1 Dip-Pen Nanolithography ..................................................................................135
4.2.2 Mechanical Stretching ........................................................................................136
4.2.3 Electrospinning ....................................................................................................136
4.2.4 Template-Directed Methods ..............................................................................136
4.2.5 Individually Addressable Single Nanowires ..................................................137
4.3 Functionalization of Conducting Polymers ..................................................................140
4.3.1 Functionalization of Conducting Polymer Nanowires ..................................142
4.4 Assembly/Fabrication of Nanowire-Based Field Effect Transistor Sensor Device 144
4.5 Label-Free Sensing using Nanowire-Based Field Effect Transistor ..........................145
4.6 Conclusions and Future Perspectives ............................................................................145
Acknowledgments ....................................................................................................................146
References ....................................................................................................................................146
4.1
Introduction
The use of biological recognition elements, such as receptors, binding proteins, antibodies,
and DNAs, as sensing elements, is particularly attractive because of their highly sensitive
and specific nature. Conventional bioaffinity-based sensors involve the use of a label or tag
to generate the necessary signal to monitor the binding event. An attractive and highly
desirable alternative to this strategy would eliminate the tagging step and, instead, would
rely on detection of the change of an inherent property of the analyte or receptor or the
molecular aggregates formed upon binding. The advantages of label-free detection include
a simple homogeneous assay format without separation and washing steps and rapid near
real-time response. The development of label-free sensing has the potential to impact basic
biological research as well as screening in medical and bioterrorism applications.
Label-free sensing using planar (two-dimensional (2-D)) thin-film as the gate of a field
effect transistor (FET) has been demonstrated. The direct label-free detection of biomolecules
by FETs is based on the change of conductance or a related property due to depletion or
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