INVESTIGADORES
ALVAREZ Vera Alejandra
capítulos de libros
Título:
POLY (VINYL ALCOHOL) HYDROGELS: INFLUENCE OF PROCESSING VARIABLES ON GENERAL BEHAVIOR AND DRUG RELEASE DEVICE PERFORMANCE
Autor/es:
JIMENA GONZÁLEZ; VERA ALVAREZ
Libro:
Advances in Materials Science Research.
Editorial:
Nova Publishers
Referencias:
Año: 2011; p. 265 - 285
Resumen:
make it an excellent candidate for several applications. One of the well known uses of
these materials is like drug delivery device for their high hydrophilicity and water uptake
capability.
Hydrogels of PVA were obtained by two different routes: chemical method (by using
a crosslinking agent, such as glutaraldehyde (GA)) and by physical method (carried out
by freezing/thawing (F/T), resulting in cryogels). The main advantages of F/T are its
easiness that does require neither high temperatures nor toxic agents as waste that can be
harmful to the human body. It is possible, for biomedical applications, that un-reacted
residue from the crosslinking agent may eluted slowly over time resulting in the release
of toxic agents; being this toxicity undesirable for pharmaceutical applications because
the activity of the drug or agent being released could be destroyed.
The properties of PVA hydrogels depend mainly on their density or degree of
crosslinking and crystallinity. Nevertheless, it is still unclear what role of processing
variables play on the significant properties of the material. These properties can be driven
by the numbers of F/T cycles, the cycle extent, the freezing temperature, the rate of
thawing, the polymer concentration and its molecular weight (Mw).
The aim of this chapter was to analyze the effect of some processing variables on the
characteristic and properties of PVA hydrogels and to look at the delivery system
behavior in aspirin and ibuprofen drugs. For this purpose, cryogels with different:
numbers of F/T cycles (1 to 4), cycles extent (1, 12 and 24 h), Mw (18000; 40500, 93500
and 155000 g/mol) and polymer concentration (5 to 15 wt.%) were synthesized andanalyzed by means of thermogravimetric analysis (TGA), differential scanning
calorimetric (DSC), swelling studies, X-ray diffraction (XRD), rheological tests and
mechanical properties. In addition, cryogels were compared with chemically based
hydrogels by means of selected characterization techniques.
The results obtained in the present study suggest that it is possible to obtain cryogels
with controlled properties and to be optimist about the future use of these kinds of
hydrogels, avoiding the use of toxic crosslinking agent, for applications such as drug
delivery.