2 research outputs found
Reduction-Responsive Cationic Vesicles from Bolaamphiphiles with Ionizable Amino Acid or Dipeptide Polar Heads
This paper presents a study of the aggregation of cationic
bolaamphiphilic
molecules into vesicles. These molecules are based on a cystamine
core with protonated terminal dipeptide groups. The study found that
vesicles can be formed at pH 4 for all of the dipeptide-terminated
bolaamphiphiles containing different combinations of l-valine, l-phenylalanine, and l-tryptophan. The concentration
for aggregation onset was determined by using pyrene as a fluorescent
probe or light dispersion for compounds with tryptophan. Dynamic light
scattering (DLS) studies and transmission electron microscopy (TEM)
reveal that the vesicles have diameters ranging from 140 to 500 nm
and show the capability of loading hydrophobic cargos, such as Nile
red, and their liberation in reductive environments. Furthermore,
the bolaamphiphiles are only fully protonated and prone to vesicle
formation at acidic pH, making them a promising alternative for gastrointestinal
delivery
Vibrational Circular Dichroism Shows Reversible Helical Handedness Switching in Peptidomimetic lāValine Fibrils
We elucidate the supramolecular organization in the form of microsize fibrils of gels formed by a l-Valine peptidomimetic compound. Analysis was based on circular dichroism spectroscopies, vibrational (VCD) and electronic (CD), supported by microscopy (atomic force and scanning electron). We show how the VCD spectra give account of the micrometric structure of the fibrils formed by the helicoidal arrangement of simpler proto-fibrils, which are organized in a lower hierarchical level. This ability is used to monitorize a fully reversible change in the handedness of the helix by modulating different external stimuli as pH or ionic strength, thus providing the first observation by VCD of such a phenomenon in a short peptide