Semiconductor colloidal quantum dots have been, for the past two decades, incorporated in a wide range of
applications from catalysis and optical sensors to biolabels. For this reason, simple, cheap and reproducible routes of
synthesis are the main goal of many research groups around the world. They seek the production of a very stable and
extremely quantum efficient nanocrystal that can afford rough changes in the external environment. Silica capping is
becoming a very common tool in the quest for a stable quantum dot, because of its strong and stable structure, this
material provides a great insulator to the nanocrystal from the outside. The nanocrystal surface is not chemically
favorable to the deposition of the bare silica shell, what demands a bifunctional molecule that provides the linkage
between the core and the shell. In this work we present a comparison between several silanization methods of thiol
capped CdSe and CdTe quantum dots, showing some simplifications of the routes and an application of the quantum dots
produced as fluorescent cell markers in acquisition of confocal microscopy images.
One of the fundamental goals in biology is to understand the interplay between biomolecules of different cells. This
happen, for example, in the first moments of the infection of a vector by a parasite that results in the adherence to the cell
walls. To observe this kind of event we used an integrated Optical Tweezers and Confocal Microscopy tool. This tool
allow us to use the Optical Tweezers to trigger the adhesion of the Trypanosoma cruzi and Trypanosoma rangeli parasite
to the intestine wall cells and salivary gland of the Rhodnius prolixus vector and to, subsequently observe the sequence
of events by confocal fluorescence microscopy under optical forces stresses. We kept the microorganism and vector cells
alive using CdSe quantum dot staining. Besides the fact that Quantum Dots are bright vital fluorescent markers, the
absence of photobleaching allow us to follow the events in time for an extended period. By zooming to the region of
interested we have been able to acquire confocal images at the 2 to 3 frames per second rate.
We present Raman-scattering results for PbTe quantum dots (QDs) in doped telluride glasses which clearly
show the confinement effects on the phonon spectra as a function of the quantum-dot size.
PbTe doped tellurite glass photonic optical fiber for non linear application were developed using rod in tube method in a
draw tower. We follow the growth kinetics of the quantum dots in the optical fiber by High Resolution Transmission
Electron Microscopy giving some results related with the growth kinetic of the same in function of time so much for
optical fiber as for the glass bulk. Absorption peak near 1500 nm as observed and it was attributed the optical resonance
due PbTe quantum dots in the core fiber.
The research in biomedical photonics is clearly evolving in the direction of the understanding of biological
processes at the cell level. The spatial resolution to accomplish this task practically requires photonics tools.
However, an integration of different photonic tools and a multimodal and functional approach will be necessary to
access the mechanical and biochemical cell processes. This way we can observe mechanicaly triggered biochemical
events or biochemicaly triggered mechanical events, or even observe simultaneously mechanical and biochemical
events triggered by other means, e.g. electricaly. One great advantage of the photonic tools is its easiness for
integration. Therefore, we developed such integrated tool by incorporating single and double Optical Tweezers with
Confocal Single and Multiphoton Microscopies. This system can perform 2-photon excited fluorescence and Second
Harmonic Generation microscopies together with optical manipulations. It also can acquire Fluorescence and SHG
spectra of specific spots. Force, elasticity and viscosity measurements of stretched membranes can be followed by
real time confocal microscopies. Also opticaly trapped living protozoas, such as leishmania amazonensis.
Integration with CARS microscopy is under way. We will show several examples of the use of such integrated
instrument and its potential to observe mechanical and biochemical processes at cell level.
A new polymeric open optical fiber with a star cross section from extruded PMMA grains was
developed. We have painted the external surface of this fiber with the Europium chelate or
Antracene. We have observed the typical luminescence of these compounds when excited with
nanosecond 355 nm pulsed laser. These results show that the developed fiber presents potentialities
for optical sensing.
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