Percorrer por autor "Silva, Diana C."
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- Functional monomer type determines the interfacial properties of experimental self-adhesive composites bonded to dentinPublication . Andrade, Rita; Chaves, Carolina; Silva, Diana C.; Serro, Ana Paula; Azul, Ana Mano; Águas, Hugo; Delgado, António H. S.Purpose: To evaluate the influence of functional monomer type and powder-to-liquid ratio on the interfacial properties and degree of conversion of experimental self-adhesive flowable resin composites (SAFRCs) bonded to dentin. Materials and Methods: Nine experimental SAFRC formulations were developed by varying the powder-to-liquid ratio (1.9, 2.2, 2.5) and the functional monomers included (10-MDP, GPDM, HEMA). Human molars (n = 27) were restored using each formulation and analyzed using a rheometer to assess viscosity, Raman micro-spectroscopy for inter-diffusion zone (IDZ) width, and degree of conversion at the interface (DC%). Two-way ANOVA and post-hoc tests were performed for statistical analysis (α = 0.05). Results: Rheological testing revealed, as expected, non-Newtonian flow behavior in all composites, with significant effects of both powder-to-liquid ratio (P 0.001) and monomer type (P 0.001) on viscosity. 10-MDP composites exhibited optimal viscosity (1.12–2.86 mPa·s) across all ratios, significantly lower than GPDM and HEMA. Raman mapping showed a distinct IDZ with hybrid characteristics for 10-MDP formulations, contrasting with abrupt transitions or gaps in GPDM and HEMA groups. IDZ width was significantly greater in 10-MDP formulations (P 0.0001). The DC% at the interface was highest for 10-MDP and HEMA formulations, exceeding 68%, while GPDM composites showed lower values (P 0.001). Conclusion: Functional monomer type critically affects the interfacial bonding performance and conversion rate of SAFRCs, with 10-MDP outperforming GPDM and HEMA in interdiffusion and adhesive quality. Variations in powder-to-liquid ratio influenced viscosity but had a limited impact on interfacial performance. Optimized formulations with 10-MDP may enhance the clinical efficacy of SAFRCs. Clinical Relevance Statement: Refining acidic-monomer chemistry and viscosity in SAFRCs could improve their bonding predictability.
- 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.
- Low friction hydrogel with diclofenac eluting ability for dry eye therapeutic contact lensesPublication . Silva, Diana C.; Oliveira, Margarida; Marto-Costa, Carolina; Teixeira, João; Oom, Madalena Salema; Pinto, Carlos A.; Saraiva, Jorge A.; Marques, Ana Clara; Fitzhenry, Laurence; Serro, Ana PaulaWhen placed in the eye, contact lenses (CLs) disturb the tear fluid and affect the natural tribological behaviour of the eye. The disruption in the contact mechanics between the ocular tissues can increase frictional shear stress and ocular dryness, causing discomfort. Ultimately, continuous CLs wear can trigger inflammation which is particularly critical for people suffering from dry eye. In this work, a double strategy was followed to obtain therapeutic daily disposable CLs for dry eye: a hydroxyethyl methacrylate (HEMA) based hydrogel was coated with two natural polysaccharides, chitosan (CHI) and hyaluronic acid (HA) and posteriorly loaded with an anti-inflammatory drug (diclofenac, DCF). Material sterilisation was carried out by high hydrostatic pressure (HHP) combined with moderate temperature. The friction coefficient (μ) was determined in the presence of different tear biomolecules (cholesterol, lysozyme and albumin) using a nanotribometer. Drug release experiments were performed in static and in hydrodynamic conditions. The material was extensively characterised, regarding surface morphology/topography, optical properties, water content and swelling behaviour, wettability, ionic and oxygen permeability and mechanical properties. It was found that the coating did not impair the physico-chemical properties relevant for the material’s application in CLs. Besides, it also ensured a sustained release of DCF for 24 h in tests performed in hydrodynamic conditions that simulate those found in the eye, increasing significantly the amount of drug released. It reduced friction, improving the lubrication ability of the hydrogel, and presented antibacterial properties against S. aureus, P. aeruginosa and B. Cereus. The coated samples did not reveal any signs of cytotoxicity or potential eye irritation. Overall, the coating of the hydrogel may be useful to produce daily CLs able to alleviate dry eye symptoms and the discomfort of CLs wearers.
- Optimal nano-silica filler concentration to optimize kinetics, rheology and bonding of self-adhesive compositesPublication . Alves, Miguel; Pereira, Pedro; Silva, Diana C.; Delgado, António H. S.To determine how silica nanoparticle (NanoSi) content modulates polymerization kinetics, dentin bonding, and interfacial adaptation in self-adhesive flowable resin composites (SAFRCs). Five UDMA/PPGDMA/10-MDP SAFRCs containing 0, 2.5, 5, 7.5, or 10 wt% NanoSi were compared to a commercial reference (Vertise Flow, VF). Real-time ATR-FTIR provided t0.5, Rpmax, delay time, and DCmax; viscosity was measured under controlled shear. Shear bond strength (SBS) was tested at 24 h. Masson’s trichrome and environmental SEM (E-SEM) assessed interfaces. Two-way MANOVA examined formulation and exposure time (20 vs 40 s) effects on kinetics; one-way ANOVA analyzed µSBS (ɑ = 0.05). Formulation and time significantly affected the multivariate kinetic response (Wilks’ λ_formulation = 0.1905, p = 0.0099; Wilks’ λ_time = 0.4296, p = 0.0045), with no interaction. NanoSi_2.5 polymerized fastest (Rpmax 3.17 ± 0.43%·s⁻1); NanoSi_5 was slowest (1.61 ± 0.26%·s⁻1). DCmax increased with filler, peaking at NanoSi_10 (78.77 ± 2.64%); extending exposure from 20 to 40 s raised DCmax by 10.23 ± 2.16% without altering kinetics. All pastes were shear-thinning, with viscosity rising monotonically with NanoSi. SBS differed among materials (ANOVA F = 3.14, p = 0.02): VF was highest (8.6 ± 2.2 MPa); NanoSi_0 reached 6.0 ± 1.1 MPa (NS vs VF); NanoSi_2.5–5 clustered lower (~ 3–4 MPa) and NanoSi_7.5 reached the minimum. Trichrome and E-SEM showed thin, continuous interfaces at 0–2.5 wt% and increasing porosity/thin separations at 7.5–10 wt%. Nanosilica altered cure, flow and interfacial quality trade-offs; faster early kinetics and higher final conversion did not translate into higher SBS, emphasizing the need to optimize interfacial wetting/adaptation alongside mechanical parameters in SAFRC design. A formulation window may exist in which flow, cure, and bonding are balanced to enhance the clinical potential of self-adhesive composites.
- 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.
- Supercritical CO₂-assisted impregnation of triamcinolone acetonide into silicone-based soft contact lenses for enhanced ocular drug deliveryPublication . Silva, Diana C.; Gonçalves, Margarida; Ekoh, Elisabeth; Salema-Oom, Madalena; Serro, Ana Paula; Nobre, Beatriz P.Soft contact lenses (SCLs) have attracted increasing attention in the field of ocular drug delivery systems, owing to their potential to improve drug bioavailability in vivo. However, the incorporation of lipophilic drugs, constitutes a significant challenge through conventional soaking methods. Supercritical carbon dioxide (scCO₂), an environmentally friend solvent, has emerged as an efficient alternative for the development of delivery systems improving the impregnation of such drugs. In this work, scCO₂ impregnation (SCI) was employed to load silicone-based hydrogels for SCLs, with triamcinolone acetonide (TA), a lipophilic corticosteroid. Design of experiments was conducted using a full factorial design to identify the most significant experimental parameters affecting TA SCI, as well as to predict the experimental conditions that maximise SCI. In vitro release assays were carried out with materials loaded by SCI and by conventional soaking. The best performing materials were subjected to an extensive characterisation (thermal behaviour, and optical, physical, chemical and mechanical properties). The results confirmed that TA-loaded SCLs can be effectively prepared using the SCI process. The highest SCI yields were obtained with materials processed at 300 bar and 60 ºC, reaching a TA amount released of 10.12 ± 0.44 µg.mg−1 dry gel, which represents a 162.2% increase compared to the conventional soaking. SCI hydrogels showed suitable properties for the intended application. Overall, the SCI process proved to be both effective, with potential for further optimisation through condition refinement.