Percorrer por autor "Serro, Ana P."
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- Chemically crosslinked PVA hydrogels for cartilage substitutionPublication . Patacho, Inês; Oliveira, Andreia S.; Nolasco, Pedro; Colaço, Rogério; Serro, Ana P.
- Development of polycarbonate urethane-based materials with controlled diclofenac release for cartilage replacementPublication . Oliveira, Andreia S.; Ferreira, Inês; Branco, Ana C.; Silva, João C.; Costa, Carolina; Nolasco, Pedro; Marques, Ana C.; Silva, Diana; Colaço, Rogério; Figueiredo-Pina, Célio; Serro, Ana P.ydrogels are very promising human cartilage replacement materials since they are able to mimic its structure and properties. Besides, they can be used as platforms for drug delivery to reduce inflammatory postsurgical reactions. Polycarbonate urethane (PCU) has been used in orthopedic applications due to its long-term biocompatibility and bio-durability. In this work, PCU-based hydrogels with the ability to release an anti-inflammatory (diclofenac) were developed, for the first time, for such purpose. The materials were reinforced with different amounts of cellulose acetate (CA, 10%, 15%, and 25% w/w) or carbon nanotubes (CNT, 1% and 2% w/w) in order to improve their mechanical properties. Samples were characterized in terms of compressive and tensile mechanical behavior. It was found that 15% CA and 2% CNT reinforcement led to the best mechanical properties. Thus, these materials were further character- ized in terms of morphology, wettability, and friction coefficient (CoF). Contrarily to CNTs, the addition of CA significantly increased the material's porosity. Both mate- rials became more hydrophilic, and the CoF slightly increased for PCU + 15%CA. The materials were loaded by soaking with diclofenac, and drug release experiments were conducted. PCU, PCU + 15%CA and PCU + 2%CNT presented similar release pro- files, being able to ensure a controlled release of DFN for at least 4 days. Finally, in vitro cytotoxicity tests using human chondrocytes were also performed and con- firmed a high biocompatibility for the three studied materials.
- Hydrogel dressings loaded with anticancer/antimicrobial Ag(I) camphorimine complexes for treatment of malignant woundsPublication . Costa, Joana P.; Silva, Diana C.; Marques, Fernanda; Muazeia, Jeremias; Leitão, Jorge H.; Pinto, Carlos A.; Saraiva, Jorge A.; Serro, Ana P.; Carvalho, M. Fernanda N. N.The treatment of skin wounds caused by metastatic lesions is often difficult because not many medicines exist that simultaneously act on cancer cells and bacteria. Such difficulty delays and sometimes compromises the treatment of oncologic patients. To contribute to face that problem a set of silver camphorimine compounds with antibacterial properties were assessed for activity against cancer cells A375 and MeWo melanoma cells using the MTT assay. From them, the silver camphorimine complex 1 displayed the highest combined anticancer and antibacterial activities and therefore was incorporated in a HEMA-based hydrogel to be used in a wound dressing. The hydrogel disks loaded with complex 1 effectively reduced suspensions of E. coli, P. aeruginosa and B. contaminans from the initial 5 × 105 CFU/mL to 0 CFU/mL after 24 and 48 h of incubation. In the case of S. aureus, a reduction of more than 99 % was observed after 24 h. However, after 48 h of incubation, the hydrogel was ineffective towards S. aureus. Although presenting a non-porous structure, the hydrogel revealed to be hydrophilic and able to retain a significant water content, allowing to keep the wound moist. Additionally, it exhibited mechanical and mucoadhesive properties suitable for treatments involving repeated and frequent dressing changes. The hydrogels were loaded with complex 1 by soaking and then sterilized by high hydrostatic pressure (HHP). Biocompatibility studies demonstrated that the loaded dressings were non-irritant and hemocompatible. The sterilization procedure did not affect the integrity of the complex, nor the drug release, which occurred in a sustained way through a non-Fickian diffusion mechanism. The dressing released 618.5 mg/cm2/24 h, with nearly 90 % of the release occurring within the first 8 h. Considering the exudate production rates of chronic wounds and the MIC and MBC values for complex 1 it is expected that the dressings will be effective as antibacterial and anticancer agents. In vivo studies will be needed to confirm the clinical potential of the dressings. However, the produced dressings offer a promising approach for both infection control and cancer therapy in chronic wounds.
- PVA-Based Hydrogels Loaded with Diclofenac for Cartilage ReplacementPublication . Branco, Ana C.; Oliveira, Andreia S.; Monteiro, Inês; Nolasco, Pedro; Silva, Diana C.; Figueiredo-Pina, Célio; Colaço, Rogério; Serro, Ana P.Polyvinyl alcohol (PVA) hydrogels have been widely studied for cartilage replacement due to their biocompatibility, chemical stability, and ability to be modified such that they approximate natural tissue behavior. Additionally, they may also be used with advantages as local drug delivery systems. However, their properties are not yet the most adequate for such applications. This work aimed to develop new PVA-based hydrogels for this purpose, displaying improved tribomechani- cal properties with the ability to control the release of diclofenac (DFN). Four types of PVA-based hydrogels were prepared via freeze-thawing: PVA, PVA/PAA (by polyacrylic acid (PAA) addition), PVA/PAA+PEG (by polyethylene glycol (PEG) immersion), and PVA/PAA+PEG+A (by annealing). Their morphology, water uptake, mechanical and rheological properties, wettability, friction coef- ficient, and drug release behavior were accessed. The irritability of the best-performing material was investigated. The results showed that the PAA addition increased the swelling and drug release amount. PEG immersion led to a more compact structure and significantly improved the material’s tribomechanical performance. The annealing treatment led to the material with the most suitable properties: besides presenting a low friction coefficient, it further enhanced the mechanical properties and ensured a controlled DFN release for at least 3 days. Moreover, it did not reveal irritability potential for biological tissues.
- PVA-based hydrogels loaded with diclofenac for cartilage replacementPublication . Branco, Ana C.; Oliveira, Andreia S.; Monteiro, Inês; Nolasco, Pedro; Silva, Diana C.; Figueiredo-Pina, Célio G.; Colaço, Rogério; Serro, Ana P.Polyvinyl alcohol (PVA) hydrogels have been widely studied for cartilage replacement due to their biocompatibility, chemical stability, and ability to be modified such that they approximate natural tissue behavior. Additionally, they may also be used with advantages as local drug delivery systems. However, their properties are not yet the most adequate for such applications. This work aimed to develop new PVA-based hydrogels for this purpose, displaying improved tribomechanical properties with the ability to control the release of diclofenac (DFN). Four types of PVA-based hydrogels were prepared via freeze-thawing: PVA, PVA/PAA (by polyacrylic acid (PAA) addition), PVA/PAA+PEG (by polyethylene glycol (PEG) immersion), and PVA/PAA+PEG+A (by annealing). Their morphology, water uptake, mechanical and rheological properties, wettability, friction coefficient, and drug release behavior were accessed. The irritability of the best-performing material was investigated. The results showed that the PAA addition increased the swelling and drug release amount. PEG immersion led to a more compact structure and significantly improved the material’s tribomechanical performance. The annealing treatment led to the material with the most suitable properties: besides presenting a low friction coefficient, it further enhanced the mechanical properties and ensured a controlled DFN release for at least 3 days. Moreover, it did not reveal irritability potential for biological tissues.