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Biopolymers valorization using biocompatible ionic liquids for biomedical applications
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In the last decades, biopolymers received much attention, especially due to its inherent properties,
such as biodegradability, biocompatibility and biological properties. However, they showed some
limitations in a wide range of applications, mainly in the biomedical field, due to their low
solubility in water and in biocompatible organic solvents. To overcome this, ionic liquids (ILs) as
low-melting organic salts appeared as an alternative dissolution agent, mainly due to their peculiar
properties, which can be tuned according to the adequate selection of the cation and anion.
In this context, this thesis aims the development of polymeric structures via biopolymer
dissolution using innovative biocompatible ILs. ILs containing pharmaceutically acceptable drugs
– namely lidocaine, procaine, and ibuprofen with anaesthetic and anti-inflammatory effects,
respectively – were synthesized to enhance the therapeutic properties of the produced
biopolymeric structures. This way, the IL will have a double role, it will act as a solvent for the
biopolymer dissolution as well as a therapeutic agent, for example for topical delivery of
anaesthetic and anti-inflammatory drugs.
Different protic ionic liquids, which are ILs that are not fully ionized, have been successfully
synthetized by acid-base reactions, using active pharmaceutical drugs as a cation (lidocaine or
procaine) combined with carboxylate anions, namely acetate, propionate, hexanoate or
ibuprofenate (anti-inflammatory properties). They have been characterized by spectroscopic
techniques (1H NMR, FTIR) to assess their structure, thermal analysis (TGA, DSC) to evaluate
their thermal stability, and viscosity studies. The prepared ILs have been tested as dissolution
agents for different biopolymers, namely chitin-glucan complex (CGC) and chitosan. In general,
the prepared ILs containing acetate or propionate anions seemed to be capable to dissolve the
CGC biopolymer (1 wt. %). The obtained polymeric structures have been characterized by
adequate methods to study their morphology (SEM), composition (FTIR), thermal (TGA, DSC)
and mechanical properties depending on their form (films or gels). FTIR studies suggested the
obtained films were composed mainly by lidocaine free base and the obtained gel was composed
mainly by procaine free base. In general, all prepared polymeric structures showed lower thermal
stability than the CGC biopolymer. The obtained gel exhibited a viscous behaviour, whereas films
exhibited hydrophilic surface and, poor mechanical properties which limits their potential for
application.
Descrição
Palavras-chave
Biopolymers ionic liquids chitin-glucan complex topical drug delivery