1,009 research outputs found
Nanocarriers based on interpolyelectrolyte complexation of Sulphated polysaccharide-b- PEG diblock copolymers and PLL
Publicado em "Journal of Tissue Engeneering and Regenerative Medicine", vol. 7, supp. 1 (2013)Glycosaminoglycans (GAGs) are integral part of the closest cellular
environment: they can be found on the cells surface and in the extracellular
matrix, where they interact with different proteins acting as local
regulator of their activity. The use of GAGs in the preparation of protein
delivery nanosystems is, therefore, prominent but so far, underexploited
mainly because of the heterogeneity (composition and molecular
weights) of natural glycans and the multistep procedures needed to
obtain GAGs’ synthetic analogues and diblock copolymers.1 Recently,
we have shown that oxime click reaction can be applied as a straightforward
methodology for the synthesis of poly(ethylene glycol) (PEG)-
hyaluronic acid (HA) diblock copolymers.2 These copolymers formed
nanosized interpolyelectrolyte complexes (45 to 150 nm) by interaction
with poly- L -lysine (PLL).3 Unfortunately, these complexes are not stable
at physiological ionic strength. Herein, we describe a strategy to
overcome this drawback; chondroitin sulphate-b-PEG diblock copolymers
(CS-b-PEG) were obtained using the same oxime click reaction.
The stronger negative charge of sulphate groups (versus the carboxilic
groups present in HA) resulted in the complexes with higher stability:
interpolyelectrolyte complexes between PLL and (CS-b-PEG) are stable
up to 260 mM ionic strenght. Because carbohydrates do not activate Tcells,
we believe that the reported herein complexes have an enormous
potential in both drug delivery and vaccination fields
Effects of Urbanization and Other Factors on Synthetic Unit Hydrographs
Paper by Albert H. Halff, Jose I. Novoa, and Louis M. Salced
Invirtiendo en capital natural: un marco para integrar la sostenibilidad ambiental en las políticas de cooperación
Tomando en cuenta la magnitud de la crisis ambiental que afecta al planeta y los estrechos vínculos existentes entre la conservación de los ecosistemas y la lucha contra la pobreza, cabría preguntarse por qué los temas de protección del medio ambiente continúan teniendo un peso relativo tan bajo en las agendas y prioridades de las agencias de cooperación internacional. En este artículo, se analizan las razones de este desequilibrio y se propone un marco conceptual con base socio-ecológica para facilitar una verdadera integración de la sostenibilidad ambiental como prioridad estratégica en las políticas y herramientas de ayuda oficial al desarrollo. Varios paradigmas y principios fundamentales emanan de este nuevo marco conceptual, que considera a los ecosistemas funcionales como un capital natural que, adecuadamente gestionado, es capaz de producir un rico y variado flujo de servicios sobre los cuales es posible construir un proceso de desarrollo social, económica y ambientalmente sostenible, además de justo en términos de equidad intra e intergeneracional
Tracing the sources of the different magnetic behavior in the two phases of the bistable (BDTA)2[Co(mnt)2] compound
A complete computational study of the magnetic properties of the two known phases of the bistable (BDTA)2[Co(mnt)2] compound is presented. The origin of their different magnetic properties can be traced to a variation in the values of the g tensor, together with a hitherto unknown change in the JAB values and their magnetic topology
- …