Percorrer por autor "Paradiso, P."
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- Drug release from liposome coated hydrogels for soft contact lenses: the blinking and temperature effectPublication . Paradiso, P.; Colaço, R.; Mata, J. L. G.; Krastev, R.; Saramago, B.; Serro, A. P.In this article, liposome-based coatings aiming to control drug release from therapeutic soft contact lenses (SCLs) materials are analyzed. A PHEMA based hydrogel material loaded with levofloxacin is used as model system for this research. The coatings are formed by polyelectrolyte layers containing liposomes of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and DMPC + cholesterol (DMPC + CHOL). The effect of friction and temperature on the drug release is investigated. The aim of the friction tests is to simulate the blinking of the eyelid in order to verify if the SCLs materials coated with liposomes are able to keep their properties, in particular the drug release ability. It was observed that under the study conditions, friction did not affect significantly the drug release from the liposome coated PHEMA material. In contrast, increasing the temperature of release leads to an increase of the drug diffusion rate through the hydrogel. This phenomenon is recorded both in the control and in the coated samples.
- Effect of H2O2 solution’s pH on the human enamel micro and nanowearPublication . Branco, A. C; Rodrigues, I.; Paradiso, P.; Polido, M.; Colaço, R.; Figueiredo-Pina, C. G.; Serro, A. P."The effect of 30% H2O2 solutions with different pH (2, 4 and 6) on the wear of human dental enamel was studied. Additionally, the whitening efficiency and changes in hardness and morphology were evaluated. The enamel tribological response was accessed through two different approaches: ball-on-plate and atomic force microscopy (AFM), the later following a tribological model based on a single asperity contact. The results showed differences in the specific wear rate and wear mechanisms between the two used approaches. Regardless of the tribological approach used, the wear resistance of enamel was lower for pH = 2. It was observed that pH = 6 leads to a safe and efficient whitening treatment."
- Effect of tetracaine on DMPC and DMPC + cholesterol biomembrane models: Liposomes and monolayersPublication . Serro, A. P.; Galante, R.; Kozica, A.; Paradiso, P.; Gonçalves da Silva, A.M.P.S.; Luzyanina, K. V.; Fernandes, A. C.; Saramago, B."Different types of lipid bilayers/monolayers have been used to simulate the cellular membranes in the investigation of the interactions between drugs and cells. However, to our knowledge, very few studies focused on the influence of the chosen membrane model upon the obtained results. The main objective of this work is to understand how do the nature and immobilization state of the biomembrane models influence the effect of the local anaesthetic tetracaine (TTC) upon the lipid membranes. The interaction of TTC with different biomembrane models of dimyristoylphosphatidylcholine (DMPC) with and without cholesterol (CHOL) was investigated through several techniques. A quartz crystal microbalance with dissipation (QCM-D) was used to study the effect on immobilized liposomes, while phosphorus nuclear magnetic resonance (31P-NMR) and differential scanning calorimetry (DSC) were applied to liposomes in suspension. The effect of TTC on Langmuir monolayers of lipids was also investigated through surface pressure-area measurements at the air-water interface. The general conclusion was that TTC has a fluidizing effect on the lipid membranes and, above certain concentrations, induced membrane swelling or even solubilization. However, different models led to variable responses to the TTC action. The intensity of the disordering effect caused by TTC increased in the following order: supported liposomes < liposomes in solution < Langmuir monolayers. This means that extrapolation of the results obtain in in vitro studies of the lipid/anaesthetic interactions to in vivo conditions should be done carefully."
- In vitro controlled drug release from contact lenses materials under physiological ocular tear flowPublication . Paradiso, P.; Mata, J.; Moutinho, M. G.; Fernandes, A. I.; Colaço, R.; Saramago, B.; Serro, A. P.