4 research outputs found
Subtissue Plasmonic Heating Monitored with CaF<sub>2</sub>:Nd<sup>3+</sup>,Y<sup>3+</sup> Nanothermometers in the Second Biological Window
Measuring
temperature in biological environments is an ambitious
goal toward supporting medical treatment and diagnosis. Minimally
invasive techniques based on optical probes require very specific
properties that are difficult to combine within a single material.
These include high chemical stability in aqueous environments, optical
signal stability, low toxicity, high emission intensity, and, essential,
working at wavelengths within the biological transparency windows
so as to minimize invasiveness while maximizing penetration depth.
We propose CaF<sub>2</sub>:Nd<sup>3+</sup>,Y<sup>3+</sup> as a candidate
for thermometry based on an intraband ratiometric approach, fully
working within the biological windows (excitation at 808 nm; emission
around 1050 nm). We optimized the thermal probes through the addition
of Y<sup>3+</sup> as a dopant to improve both emission intensity and
thermal sensitivity. To define the conditions under which the proposed
technique can be applied, gold nanorods were used to optically generate
subtissue hot areas, while the resulting temperature variation was
monitored with the new nanothermometers
Light Management in Upconverting Nanoparticles: Ultrasmall Core/Shell Architectures to Tune the Emission Color
Ultrasmall
NaGdF<sub>4</sub> nanoparticles with core/shell and
core/shell/shell architectures have been synthesized following a microwave-based
thermolysis procedure, allowing us to rapidly obtain homogeneous nanoparticles
compared to conventional heating. To analyze the possibilities of
the proposed structure in terms of tuning the emission color, core
and shells have been doped with different lanthanide ion pairs (either
Er<sup>3+</sup>/Yb<sup>3+</sup> and/or Tm<sup>3+</sup>/Yb<sup>3+</sup>), keeping them therefore spatially separated inside the different
layers of the nanoparticles. Here, we demonstrate that the position
of the dopants inside the nanoparticles affects the intensity of the
different emission bands of the luminescing Tm<sup>3+</sup> and Er<sup>3+</sup> ions and show how it has a relevant effect on the overall
emission color of the luminescence obtained after 975 nm excitation
Temperature-Induced Energy Transfer in Dye-Conjugated Upconverting Nanoparticles: A New Candidate for Nanothermometry
Lanthanide-doped upconverting nanoparticles
(UCNPs) are highly
promising candidates for bioimaging and for cellular nanothermometry
as a novel diagnostic tool. Aiming for the diagnosis of diseases at
very early stages in order to optimize therapy and recovery of the
patient, it must be taken into account that thermal singularities
are often one of the first indicators of a disease. It is therefore
our goal to develop a nanothermometer based on UCNPs that is suitable
to detect the temperature at a subcellular level in the physiological
range. Thus, upconverting NaGdF<sub>4</sub>:Er<sup>3+</sup>,Yb<sup>3+</sup> nanoparticles that convert near-infrared (NIR) into visible
(VIS) light are synthesized by thermal decomposition. Appropriate
surface modification with a thermoresponsive polymer pNIPAM (poly(<i>N</i>-isopropylacrylamide)) guarantees dispersibility in aqueous
media required for biomedical applications. In a further step, the
combination of the obtained UCNPs with an organic dye (FluoProbe532A)
provides potential donor-acceptor-pairs allowing for energy transfer
processes, whereas the light emitted by the Er<sup>3+</sup> ions (donors)
is absorbed by the organic dye (acceptor). It has been demonstrated
that the dye-conjugated UCNPs undergo a temperature-dependent energy
transfer process inducing a temperature-dependent increase in the
thermal sensitivity when compared to unlabeled UCNPs. This result
indicates the great potential of the presented nanoprobes for applications
in nanothermometry
Sensitive Detection of ssDNA Using an LRET-Based Upconverting Nanohybrid Material
Water-dispersible,
optical hybrid nanoparticles are preferred materials
for DNA biosensing due to their biocompatibility. Upconverting nanoparticles
are highly desirable optical probes in sensors and bioimaging owing
to their sharp emission intensity in the visible region. We herein
report a highly sensitive ss-DNA detection based on an energy transfer
system that uses a nanohybrid material synthesized by doping NaYF<sub>4</sub>:Tm<sup>3+</sup>/Yb<sup>3+</sup> upconverting nanoparticles
(UCNPs) on silica coated polystyrene-<i>co</i>-acrylic acid
(PSA) nanoparticles (PSA/SiO<sub>2</sub>) as the donor, and gold nanoparticles
(AuNPs) decorated with Ir(III) complex as the acceptor. UCNPs tagged
on PSA/SiO<sub>2</sub> and the cyclometalated Ir(III)/AuNP conjugates
were then linked through the ss-DNA sequence. Sequential addition
of the target DNA to the probe molecular beacon complex resulted in
the separation of the optical nanohybrid material and the quencher,
leading to a measurable increase in the blue fluorescence emission
intensity. Our results have shown a linear relationship between the
fluorescence intensity and target DNA concentration down to the picomolar