Ultrathin Gold Nanowire Biosensors

Testicular cancer is the most common cancer found in males aged between 20 and 39 years. Early detection of the cancer has sufficient benefits to the patient because the treatment is less complicated and can be performed without having a significant effect on fertility. The research in this study will provide a new way of achieving early detection in a non-invasive manner. The principle is to use ultrathin gold wires (approximately one hundred thousand times smaller than a human hair) to electrically sense the presence of small quantities of specific biomarker proteins (HCG). The sensor works by simply flowing a current through the ultrathin gold nanowires. After the attachment of the HCG protein onto the specifically biofunctionalised nanowire, we will be able to detect a change in the electrical current flowing through the wire. This will be the first time ultrathin metal wires have been used in this manner to detect proteins. Once proven successful we will study the ability of these nanowires to sense other important biomarker proteins. During the course of this research I will be performing four-probe transport measurements on chemically synthesized ultrathin gold nanowires to determine the effect the nanoscale dimensions have on the resistivity. In addition to the experiments, we will be generating computation models to provide us with a detailed fundamental understanding of the sensing capability of ultrathin NWs. Beyond this research program, we plan to extend the biosensing capabilities of the NWs to detect other cancers and diseases.

Research into ultrathin nanowire sensors has many beneficiaries and these can be broken down into Academic, Public Sector, Business, Schools and Education, and the General Public. First let us consider academic impact. The nature of the proposed multi-disciplinary research means that the impact of the work branches into several major scientific and engineering fields. The research program will be engaging in the fundamental understanding of transport of ultrathin nanowires. This means revisiting the physics of surface scattering of electrons using a quantum mechanical description and going much further than the classical models that are regularly referenced. An improved understanding of the surface effects have on ultrathin structures will enable scientists to develop more effective strategies for reducing the dimensions of interconnects, whilst minimising the resistance. This could have the potential to change the way electronic engineers choose to deposit nanoscale connections and perhaps have a long-term goal of increasing the speed of chips (reducing the RC switching time- adding to the digital economy) and loss of energy through heat (impacting environment and energy). The synthesis of the nanowires is achieved by chemical synthesis. New information gained from this study will have an impact for improving the understanding of self-assembly and directed assembly, which is very important to chemists, nanotechnologists and nanoscientists. Biologists are another beneficiary, particularly in the longer term. By developing biosensors, we will be enabling a new platform for protein immobilization and study of proteins of interest. Furthermore, there is scope to study alternative antibody mimics with superior properties to traditional monoclonal antibodies. All of these academic beneficiaries will learn about our work through traditional and non-traditional means scientific journals, conference presentations, seminars, the media and web-based information.
In the longer term the public sector will also benefit from the development of new biosensors, which will reduce the cost of many diagnostic tests and this will directly benefit the NHS. Reducing the cost of tests allows an increase in the use of diagnostics and it has already been demonstrated that in many cases early screening of cancer can significantly improve the prognosis of a patient. Furthermore, quantitative diagnostic tests can be used to monitor the prescribed treatment to track the effectiveness, which help provide the personalized medicine that is important to the General Public.
The business sector will also gain from the development of novel nanowire materials with various potential applications from biosensors, catalysts, elements of fuel cells, to in-vivo imaging probes will generate commercial opportunities. This comes in the form of intellectual property, generation of wealth through selling products (nanowires and nanowire devices), which provides assistance to the economic sector.
Schools. Through the use of outreach programs we will inspire the next generation of UK scientists and engineers to become future leaders.