Controlled Assembly of Carbon Nanotube Nanohybrids: Single-Molecule Investigations and Beyond 

Dr Matteo Palma

Department of Chemistry

Queen Mary University of London, UK.

Wednesday 10th January, 3pm, Ramsay Lecture Theatre


We present a universal approach for the generation of multifunctional nanomaterials that employ molecular building blocks assembled on carbon nanotube (CNTs) electrodes. We will demonstrate single-molecule control in the formation of both static and dynamic nanohybrids via the in-solution assembly of classes of molecular materials (organic, inorganic, and biological with promising attributes) to DNA wrapped CNTs. We will first discuss the in-solution linking of metallic single-walled CNTs (SWCNTs) with different conjugated molecular wires. Conductive atomic force microscopy measurements performed at different locations along the junctions (Figure 1a), allowed us to measure the molecular conductance of a series of oligophenyls, highlighting the potential of an all-carbon based approach for solution-processable molecular electronics.[1]Furthermore, we produced organic-inorganic heterostructures consisting of single Quantum Dots (QDs) univocally linked at the terminal ends of individual SWCNTs. Monofunctionalized SWCNT-QD heterostructures were obtained and photophysical investigations at the single nanohybrid level showed evidence of electronic coupling (Figure 1b).[2]Moreover, DNA linkers of differing lengths were used as molecular rulers to control the distance, and hence tune the energy/charge transfer between the two nanostructures. A dynamic SWCNT-QD hybrid was assembled using a G-quadruplex DNA linker; the distance between the SWCNT and QD was then be dynamically modulated by the introduction and removal of potassium ions (K+);[3]the system was further found to be sensitive to K+ concentrations from 1pM to 25mM. Additionally, we will demonstrate the selective electrical addressability of proteins via the use of carbon nanoelectrodes.  We investigated different one-to-one CNT-protein configurations and obtained single-molecule evidence of site-specific coupling between SWCNTs and specific proteins of interest (Figure 1c).[4]Finally, we will we present a strategy for the fabrication of reconfigurable and solution processable nanoscale biosensors with multi-sensing capability, based on SWCNTs. The CNTs were functionalised with specific nucleotide sequences that were employed as selective recognition elements for biomarkers indicative of stress and neuro-trauma conditions. Multiplexed detection of three different biomarkers was successfully performed and real-time detection was achieved in serum with concentrations down to 50 nM, 10 nM and 500 pM.[5]By and large, we demonstrate a novel in-solution approach for the assembly of individual molecules on carbon nanotube electrodes with single-molecule control. The assembled heterostructures show promise in the fabrication of solution-processable nanoelectronic devices for applications that range from molecular electronics to sensing.

References

[1] J. Zhu, J. McMorrow, R. Crespo-Otero, G. Ao, M. Zheng, W. P. Gillin, M. Palma, J. Am. Chem. Soc., 2016, 138, 2905-2908

[2] A. Attanzio, A. Sapelkin, F.Gesuele, A. van der Zande, W. P. Gillin, M. Zheng, M. Palma, Small, 2017, 13, 1603042

[3] M. Freeley, A. Attanzio, A. Cecconello, G. Amoroso, P.Clement, F. Gesuele, M. Palma Submitted

[4] M. Freeley, H. L. Worthy, R. Ahmed, B. Bowen, J. E. Macdonald, M. Zheng, D.D. Jones, M. Palma, J. Am. Chem. Soc. 2017, 139, 17834

[4] X. Xu, P. Clement, J. V. R. Eklöf, N. Kelley-Loughnane, K. Moth-Poulsen J. L. Chávez, M. Palma, Submitted