OVERVIEW ON THE MAJOR RESEARCH ACTIVITIES ON CARBON NANOTUBES BEING DONE IN AMERICA, EUROPE AND ASIA - Carbon Nanotubes: From Bench Chemistry to Promising Biomedical Applications - page 277

On the other hand, it has been proved that CNT photoluminescence
is quenched by external electric ields, as demonstrated by the drastic
reduction in emission intensity when ields ≤ 10 7 V/m were applied. 132 In
more detail, photoluminescence intensity was found to follow a reciprocal
hyperbolic cosine dependence on the applied electric ield. Therefore, the
use of NIR luminescence provides useful information that substantiated the
application of CNTs as luorescent markers. At the same time, it also offers the
opportunity to explore biological systems through biosensing and accurate
bio-imaging. With regards to this aspect, the research goup has performed
some biocompatibility studies in Drosophila melanogaster (fruit lies). 133
In the experiments, Drosophila larvae were nourished on food containing
approximately 10 ppm of disaggregated SWCNTs, showing normal growth
following nanotube ingestion. NIR nanotube luorescence was imaged from
intact living larvae, and it proved extremely useful at identifying and counting
isolated SWCNTs to gain an estimation of their biodistribution.
However, while the NIR luminescence of CNTs has been deeply
investigated, the exploration on far-ield near-IR of SWCNTs has been
limited by the diffraction limit to resolution. Once again, the researchers
were able to overcome the problem through a new analytic method that
allowed subwavelength (< λ /10) mapping of single-molecule and the precise
localisation of excitonic luminescence regions along the nanotube axis. 134 This
new method seems very useful at revealing lengths, curvatures and defects of
luminescent SWCNTs with unprecedented details.
9.2.5 USA
Michael S. STRANO
@ Massachussets Institute of Technology (MIT)
Website (research activities): http://web.mit.edu/stranogroup/
research.html
Expertise: Optical modulation of nanostructures for sensor applications,
chemistry of single-walled carbon nanotubes, and molecular interactions
with nanoelectronic sensor arrays
9.2.5.1 CNT-basedsensors
Strano's research group is mainly focused on the development of carbon-
based sensors for biological detection. This is because SWCNTs possess many
advantages when used as optical sensors, including photostable intrinsic
NIR emission for prolonged detection through biological media and single-
molecule sensitivity. However, a big challenge in the fabrication of such