Increasing the Bile Acid Sequestration Performance of Cationic Hydrogels by Using an Advanced/Controlled Polymerization Technique
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To investigate the influence of the polymerization technique and the content of hydroxyl groups on the performance of new bile acid sequestrants based on PAMPMTA-co-PHEA (PAMPTMA: poly((3-acrylamidopropyl)trimethylammonium chloride); PHEA: poly(2-hydroxyethyl acrylate)) hydrogels.
PAMPMTA-co-PHEA hydrogels were prepared using either free radical polymerization or supplemental activator and reducing agent atom transfer radical polymerization. The chemical structure and composition of the hydrogels was confirmed by both FTIR and ssNMR. The binding of sodium cholate as the model bile salt was evaluated in simulated intestinal fluid using HPLC. The degradation of the polymers was evaluated in vitro in solutions mimicking the gastrointestinal tract environment.
The binding showed that an increase of the amount of HEA in the hydrogel lead to a decrease of the binding capacity. In addition, it was demonstrated for the first time that the hydrogels produced by SARA ATRP presented a higher binding capacity than similar ones produced by FRP. Finally, it was observed that copolymers of PAMPTMA-co-PHEA showed no sign of degradation in solutions mimicking both the stomach and the intestine environment.
The use of an advanced polymerization technique, such as the SARA ATRP, could be beneficial for the preparation of BAS with enhanced performance.
KEY WORDSbile acid sequestrants (BAS) cationic hydrogel free radical polymerization (FRP) supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP)
Bile acid sequestrants
Free radical polymerization
High performance liquid chromatography (HPLC)
- SARA ATRP
Supplemental activator and reducing agent atom transfer radical polymerization
Simulated gastric fluid
Simulated intestinal fluid
Acknowledgments and Disclosures
Patrícia Mendonça acknowledges FCT-MCTES for her postdoctoral grant (Project PTDC/CTMPOL/6138/2014). AFS thanks FCT (Fundação para a Ciência e Tecnologia) and POPH/FSE for the postdoctoral grant (SFRH/BPD/73383/2010). 1H NMR data was collected at the UC-NMR facility which is supported in part by FEDER – European Regional Development Fund through the COMPETE Programme (Operational Programme for Competitiveness) and by National Funds through FCT – Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) through grants REEQ/481/QUI/2006, RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012, and Rede Nacional de Ressonância Magnética Nuclear (RNRMN). The authors would like to thank Bluepharma for the technical and scientific discussions regarding the BAS technology. Also, Doctor Luís Mafra is strongly acknowledge for the fruitful scientific discussions regarding 13C HPDEC ssNMR spectroscopy.
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