Abstract
Organic inorganic hybrids present several advantages as drug release systems, such as: high flexibility, high mechanical and thermal resistance, transparency, and low water solubility. These hybrids are synthesized through a chemical route named sol-gel that usually uses as solvente tetrahydrofuran (THF). Objetives: To develop film formers from hybrid materials replacing THF with ethanol, a less toxic solvent for skin application and for the environment. Methods: Four polymers were used: two based on polyethylene oxide (PEO) with molecular weight of 500 and 1900 g mol-1 and two based on polypropylene oxide (PPO), with molecular weight of 400 and 2000 g mol-1. The structural analysis was performed by FTIR, 1H-NMR and 29Si-NMR, and the thermal-mechanical analysis by DSC and TG-DTA. Results: The results of the thermo-mechanical analysis revealed that the solvent replacement did not affect the thermal stability and flexibility of the di-ureasil hybrid. Conclusions: Structural characterization confirmed the formation of hybrids both in THF and in ethanol. Therefore, ethanol is an excellent solvent for the synthesis of these hybrid matrices, since it allows obtaining the same material without changing its characteristics, with some advantages, however, over THF. Furthermore, this paper describes the efficiency of ethanol as a solvent, which is environmentally friendly, to replace THF in the physical-chemical characteristics of these filming former materials.
Highlights
INTRODUCTIONThe interest in different fields in new technologies for controlled release has been increasing in recent years, as these systems have advantages over conventional[1,2,3,4] ones, such as reduced toxicity, prolonged time in the bloodstream, gradual and controlled release of the drug, safe and adequate administration, targeting to specific organs, and the ability to incorporate hydrophilic and lipophilic substances[5,6]
The interest in different fields in new technologies for controlled release has been increasing in recent years, as these systems have advantages over conventional[1,2,3,4] ones, such as reduced toxicity, prolonged time in the bloodstream, gradual and controlled release of the drug, safe and adequate administration, targeting to specific organs, and the ability to incorporate hydrophilic and lipophilic substances[5,6].Financial support: FAPESP – Fundação de Amparo à Pesquisa do Estado de São Paulo or Foundation for Research Support of the State of São Paulo, process number 2017/21456-3
The functionalized polyethylene oxide (PEO) or polypropylene oxide (PPO) was dissolved in THF or ethanol and added to a three-necked round-bottomed flask equipped with a mechanical stirrer, and reflux condenser
Summary
The interest in different fields in new technologies for controlled release has been increasing in recent years, as these systems have advantages over conventional[1,2,3,4] ones, such as reduced toxicity, prolonged time in the bloodstream, gradual and controlled release of the drug, safe and adequate administration, targeting to specific organs, and the ability to incorporate hydrophilic and lipophilic substances[5,6]. The transparency is a feature desired in some pharmaceuticals and cosmetics systems, as it increases patient acceptability and allows the physician to monitor the healing process. These hybrids are synthesized and processed through the chemical route known as solgel[9,10,11,12]. Several human studies show that THF is readily absorbed from the respiratory tract This solvent is absorbed through the skin and the THF vapors may cause irritation of mucous membranes, respiratory system and skin[13,14]. In this work, we show that ethanol, an environmentally friendly solvent, can be successfully employed in replacing THF in the synthesis of ureasil-polyether film forming hybrids
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