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Natural melanin: A potential pH-responsive drug release device

Publication . Araújo, Marco; Viveiros, Raquel; Correia, Tiago R.; Correia, Ilídio Joaquim Sobreira; Bonifácio, Vasco; Casimiro, Teresa; Ricardo, Ana Aguiar

This work proposes melanin as a new nanocarrier for pH-responsive drug release. Melanin is an abundant natural polymer that can be easily extracted from cuttlefish as nanoparticles with a suitable size range for drug delivery. However, despite its high potentiality, the application of this biopolymer in the pharmaceutical and biomedical fields is yet to be explored. Herein, melanin nanoparticles were impregnated with metronidazole, chosen as model antibiotic drug, using supercritical carbon dioxide. The drug release profile was investigated at acidic and physiologic pH, and the dominant mechanism was found to follow a non-Fickian transport. Drug release from melanin shows a strong pH dependency, which allied to its biocompatibility and lack of cytotoxicity envisages its potential application as nanocarrier in formulations for colon and intestine targeted drug delivery.

2014-04-23Journal article

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Development of 2-(dimethylamino)ethyl methacrylate-based molecular recognition devices for controlled drug delivery using supercritical fluid technology

Publication . Silva, Mara da; Viveiros, Raquel; Morgado, Patrícia I.; Ricardo, Ana Aguiar; Correia, Ilídio Joaquim Sobreira; Casimiro, Teresa

This work reports the development of a novel potential body-friendly oral drug delivery system, which consists of a biocompatible molecularly imprinted polymer (MIP), with pH sensitive character and low cross-linking degree (20.2 wt%), synthesized and processed in supercritical carbon dioxide. The MIP is synthesized using 2-(dimethylamino)ethyl methacrylate (DMAEMA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker, and ibuprofen as molecular recognition template. The imprinted matrix was able to show a higher affinity towards ibuprofen than its corresponding non-imprinted polymer (NIP) meaning that the molecular imprinting in scCO2 was efficient even using a low crosslinking degree. MIP showed a significant molecular recognition towards the template, presenting higher drug uptake ability in the supercritical impregnation step, loading 33.1 wt% of ibuprofen compared to only 10.2 wt% for the NIP polymer. In vitro drug release experiments, simulating an oral administration, showed different release profiles at pH 2.2 and pH 7.4. Zeta potential measurements were performed to both MIP and NIP showing that the imprinting process has a significant influence on the charge of the polymeric particles. Cytotoxicity assays performed with human colorectal carcinoma-derived Caco-2 cells demonstrated that the polymers are biocompatible and could be potentially used in drug delivery applications.

2011-06-20Journal article

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