O cromoglicato de sódio é um derivado sintético do biscromona, vastamente aplicado para uso na profilaxia, em especial para controle adjuvante da asma ou inflamação brônquica. O cromoglicato de sódio apresenta uma fórmula molecular é C23H14Na2O11 com massa molar de
512 g.mol-1, relativa solubilidade em água e insolubilidade em solventes orgânicos como, álcool,
clorofórmio e éter (Alani e Robinson, 2008; CANTRELL, 2005).
A representação estrutural da molécula do cromoglicato dissódico, também conhecido como cromoglicato de sódio, pode ser verificada na Figura 10. A estrutura da molécula sugere que sua hidrofilicidade é devida a presença de diversos grupos substituintes de natureza polar, sendo os grupos carboxila os que possuam maior contribuição na carga negativa das moléculas, uma vez que a ligação entre os grupos carboxilato e os cátions sódio podem ser rompida pelos efeitos de solvatação das moleculas de agua, gerando grupos aniônicos do tipo carboxilato.
Figura 10 - representação da estrutura química do Cromoglicato dissódico
O cromoglicato de sódio possui carga negativa quando em solução aquosa e de modo reciproco ao observado para as moléculas de tetraciclina no item 2.5.2, a sorção dessas moléculas pode ocorrer com interações mais efetivas em partículas com superfície positivamente funcionalizadas.
3 OBJETIVOS
3.1 OBJETIVO GERAL
O objetivo geral deste trabalho é a preparação e caracterização magnética e microestrutural de compósitos magnéticos obtidos por complexação interpolieletrolítica entre a quitosana e o poli (4-estirenossulfonato de sódio) em presença de nanopartículas de magnetita.
3.2 OBJETIVOS ESPECÍFICOS
Como objetivos específicos destacam-se:
Estudar as propriedades dos compósitos obtidos em razões molares 0,70 e 1,43 entre a concentração dos grupos sulfonato e amino;
Investigar a composição dos sistemas por TGA e FTIR;
Analisar as características microestruturais dos sistemas por DRX e TEM;
Estudar a influência das razões molares na carga superficial dos compósitos através de medidas de potencial zeta em diferente valores de pH;
Estudar as propriedades magnéticas dos compósitos e sua relação com a temperatura; Investigar o potencial dos compósitos na adsorção dos fármacos tetraciclina e
4 CONSIDERAÇÕES FINAIS
Os Compósitos magnéticos (CMs) foram obtidos espontaneamente através da complexação interpolieletrolítica entre a Quitosana (CS) e o Poli (4 - Estireno Sulfonato de sódio) (NaPSS) em presença de nanopartículas de magnetita. A caracterização composição e estrutura dos CMs evidenciaram a formação de uma sistema composto por nanopartículas de magnetita dispersas em uma matriz polimérica, composta pelo complexo interpolieletrolítico entre Cs e o NaPSS. As medidas de potencial zeta indicaram uma carga negativa ou positiva para os CMs, de acordo com as razoes 1.43 e 0.7, respectivamente. A caracterização microestrutural comprovou a formação na magnetita e evidenciou uma distribuição de tamanhos população majoritária entre 9 e 13 nm, a qual se manteve praticamente inalterada para a magnetita dispersa nos compósitos. A caracterização magnética mostrou que os compósitos magnéticos apresentam comportamento superparamagnético em condições de temperatura ambiente (25°C).
Os ensaios de remoção indicaram uma tendência a sorção dos CMs para ambos os fármacos estudados. De modo que para os a tetraciclina a carga superficial dos CMs não apresentou uma influência significativa no percentual de fármaco removido. No entanto, o compósito magnético de carga superficial oposta a carga parcial do o cromoglicato de sódio, apresentou um aumento de 20 % no percentual de remoção.
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