3 research outputs found
Double Charge Inversion in Polyethylenimine-Decorated Liposomes
The study of the interaction of a cationic polymer as
PEI with
phospholipids membranes is of special relevance for gene therapy because
the PEI is a potential nonviral vector to transfer DNA in living cells.
We used light scattering, zeta potential, and electron transmission
microscopy to characterize the interaction between DMPG and DOPC liposomes
with PEI as a function of the charge molar ratio, pH, temperature,
initial size of the liposomes, and headgroup of the lipids. Unexpectedly,
a double charge inversion and two different ranges of PEI–liposome
concentrations where an aggregation occurs were found, when the proper
pH and initial size of the liposomes were chosen. The interaction
is analyzed in terms of the interaction potential proposed by Velegol
and Thwar for colloidal particles with a nonuniform surface charge
distribution. Results show a remarkable dependence of the stability
on pH and the initial size of the liposomes, which explains the low
reproducibility of the experiments if no special care is taken in
preparing the samples. Comparatively small changes in the pH or in
the liposomes size lead to a completely different stability behavior
Nanoreactors for Simultaneous Remote Thermal Activation and Optical Monitoring of Chemical Reactions
We
report herein the design of plasmonic hollow nanoreactors capable
of concentrating light at the nanometer scale for the simultaneous
performance and optical monitoring of thermally activated reactions.
These reactors feature the encapsulation of plasmonic nanoparticles
on the inner walls of a mesoporous silica capsule. A Diels–Alder
cycloaddition reaction was carried out in the inner cavities of these
nanoreactors to evidence their efficacy. Thus, it is demonstrated
that reactions can be accomplished in a confined volume without alteration
of the temperature of the bulk solvent while allowing real-time monitoring
of the reaction progress
Loss-Mitigated Collective Resonances in Gain-Assisted Plasmonic Mesocapsules
Inherent optical losses of plasmonic
materials represent a crucial
issue for optoplasmonics, whereas the realization of hierarchical
plasmonic nanostructures implemented with gain functionalities is
a promising and valuable solution to the problem. Here we demonstrate
that porous silica capsules embedding gold nanoparticles (Au NPs)
and fabricated at a scale intermediate between the single plasmonic
nanostructure and bulk materials show remarkable form–function
relations. At this scale, in fact, the plasmon–gain interplay
is dominated by the location of the gain medium with respect to the
spatial distribution of the local field. In particular, the hollow
spherical cavities of these structures allow regions of uniform plasmonic
field where the energy transfer occurring between chromophoric donors
and the surrounding plasmonic acceptors gives rise to a broadband
attenuation of losses