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Advisor(s)
Abstract(s)
O interesse nos sistemas de libertação controlada e dos materiais nanoporosos que cons-tituem estes sistemas fez estender as investigações sobre novos materiais, com proprie-dades físicas específicas.
Neste trabalho desenvolveu-se uma metodologia experimental que utiliza uma técnica de cromatografia frontal num sistema HPLC, com o intuito de medir isotérmicas de ad-sorção da cafeína e do diclofenac (este conhecido como Voltaren), permitindo medir o grau de encapsulação e a eficiência da libertação controlada. Para tal, foram testados dois tipos materiais porosos: os MOFs, ZIF-8 e MIL-100 e também o carvão ativado Norit SX PLUS, como potenciais sistemas de encapsulação e libertação controlada.
No presente trabalho foi possível verificar que a capacidade de adsorção de diclofenac sobre o carvão ativado NORIT Sx Plus é bastante elevada com valores que podem atin-gir 385 mg/g para concentrações de diclofenac Na ordem dos 30 mg/L.
Por outro lado, observou-se que a quantidade adsorvida pelos MOFs aumenta com o aumento da concentração do fármaco, mas a sua capacidade de encapsulação é pequena nas condições utilizadas ocorrendo a rutura do diclofenac e da cafeína logo após 1 min. Por esse facto, a quantidade adsorvida da cafeína e diclofenac nos MOFs não ultrapassa 0.6 mg/L.
Foi também avaliada a libertação dos fármacos adsorvidos através de experiências de dessorção, verificou-se que apenas 12% da massa adsorvida de diclofnac no carvão ati-vado é libertada. No caso dos MOFs, a massa libertada de diclofenac pode chegar até aos 87% num intervalo de tempo comparável ao da etapa de adsorção, demonstrando que nestes materiais a resistência à transferência de massa é baixa.
The interest in controlled release systems using nanoporous materials has increased sig-nificantly during recent years in part doing to the discovery of new porous material such as the MOFs and PCPs. In this paper a methodology was developed using frontal chromatography in a HPLC system, with the aim of measuring adsorption isotherms of caffeine and diclofenac (Voltaren known as such), the degree of encapsulation and efficiency and release. To this end, we tested two types porous materials: the MOFs, ZIF-8 and MIL-100 and also the classic activated carbon Norit SX PLUS, as potential systems for controlled release and encapsulation. The study has shown that the adsorption capacity on diclofnac in activated carbon NORIT Sx Plus is quite high with values that can reach 350 mg/g for concentrations of diclofenac in liquid phase until 30 mg/L. In the case of MOFs, it was observed that the amount adsorbed increases with increas-ing concentration of drug, but its capacity is small when compared to activated carbon with breakthroughs of diclofnac and caffeine occurring after 1 min. Therefore, the amount adsorbed caffeine and diclofenac in MOFs not exceed 0.6 mg / L. It was also evaluated the release of adsorbed drugs by desorption experiments, where it was found that only 12% of the mass of diclofnac adsorbed on activated charcoal is re-leased. In the case of MOFs diclofnac is easily released with amounts reaching up to 87% in a time interval comparable to the adsorption stage, demonstrating that these ma-terials offer no resistance to mass transfer.
The interest in controlled release systems using nanoporous materials has increased sig-nificantly during recent years in part doing to the discovery of new porous material such as the MOFs and PCPs. In this paper a methodology was developed using frontal chromatography in a HPLC system, with the aim of measuring adsorption isotherms of caffeine and diclofenac (Voltaren known as such), the degree of encapsulation and efficiency and release. To this end, we tested two types porous materials: the MOFs, ZIF-8 and MIL-100 and also the classic activated carbon Norit SX PLUS, as potential systems for controlled release and encapsulation. The study has shown that the adsorption capacity on diclofnac in activated carbon NORIT Sx Plus is quite high with values that can reach 350 mg/g for concentrations of diclofenac in liquid phase until 30 mg/L. In the case of MOFs, it was observed that the amount adsorbed increases with increas-ing concentration of drug, but its capacity is small when compared to activated carbon with breakthroughs of diclofnac and caffeine occurring after 1 min. Therefore, the amount adsorbed caffeine and diclofenac in MOFs not exceed 0.6 mg / L. It was also evaluated the release of adsorbed drugs by desorption experiments, where it was found that only 12% of the mass of diclofnac adsorbed on activated charcoal is re-leased. In the case of MOFs diclofnac is easily released with amounts reaching up to 87% in a time interval comparable to the adsorption stage, demonstrating that these ma-terials offer no resistance to mass transfer.