Loading...
14 results
Search Results
Now showing 1 - 10 of 14
- D-α-tocopheryl polyethylene glycol 1000 succinate functionalized nanographene oxide for cancer therapyPublication . Diogo, Duarte Miguel de Melo; Silva, Cleide Isabel Pais; Costa, Elisabete C.; Louro, Ricardo; Correia, Ilídio Joaquim SobreiraAim: To evaluate the therapeutic capacity of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)-functionalized nanographene oxide (nGO) in breast cancer cells. Methods: TPGS-functionalized nGO-based materials were obtained through two different approaches: a simple sonication method and a one-pot hydrothermal treatment. Results: TPGS coating successfully improved the stability of the nGO-based materials. The nanomaterials that underwent the hydrothermal procedure generated a 1.4- to 1.6-fold higher temperature variation under near infrared laser irradiation than those prepared only by sonication. In vitro, the TPGS/nGO derivatives reduced breast cancer cells’ viability and had an insignificant effect on healthy cells. Furthermore, the combined application of TPGS/nGO derivatives and near infrared light generated an improved therapeutic effect. Conclusion: TPGS/nGO derivatives are promising materials for breast cancer phototherapy.
- Electronic Structure of Low-Spin Ferric Porphyrins: 13C NMR Studies of the Influence of Axial Ligand OrientationPublication . Louro, Ricardo; Correia, I. J.; Brennan, Lorraine; Coutinho, Isabel; Xavier, António; Turner, DavidHeteronuclear multiple quantum NMR is used to measure the paramagnetic 13C shifts of the α substituents of the hemes in five different tetraheme ferricytochromes c3. The shifts of the 20 bis-histidine ligated hemes are assigned and then analyzed in terms of a model based on the π molecular orbitals of the heme under perturbed D4 symmetry, which yields the orientation of the rhombic perturbation, θ, and an energy splitting parameter, ΔE. Comparison of these parameters with crystal structures provides a test of the nature and extent of the influence of axial ligand orientation on the electronic structure of the heme. Despite possible differences between structures in solution and in the crystal, a clear correlation is found between θ and the resultant of the normals to the imidazole planes, and between ΔE and the angle between the normals. A weaker dependence of ΔE upon θ is also apparent. This is analogous to the results of low-temperature EPR studies of model compounds, which have been attributed to pseudo-Jahn−Teller distortion of the porphyrin. However, the effect is also predicted by extended Hückel calculations made with undistorted geometries. This work demonstrates that the variation in the electronic structure of bis-histidinyl hemes c is dominated by the geometry of the axial ligands and that other perturbations, such as asymmetric substitution of the porphyrin or low symmetry of the surrounding protein, are relatively minor. The correlations with θ and ΔE can, therefore, be used to determine the ligand geometry with sufficient accuracy to detect differences between structures in solution and in the crystal. The analysis can also be used to locate the principal axes of the magnetic susceptibility tensors of ferrihemes as well as providing orientational constraints for the axial ligands for the calculation of solution structures of paramagnetic proteins. This is particularly important since paramagnetic relaxation may make it impossible to observe NOE effects to the imidazole protons, leaving the geometry of the heme pocket poorly defined.
- Breast cancer targeted photothermal therapy mediated by hyaluronic acid functionalized reduced graphene oxidePublication . Sousa, Ana Rita Lima; Diogo, Duarte de Melo; Alves, Cátia Gomes; Costa, Elisabete; Louro, Ricardo; Mendonça, António G.; Correia, I.J.The use of graphene-based nanomaterials in cancer photothermal therapy (PTT) is an emerging alternative to the currently available cancer treatments. In this regard, reduced graphene oxide (rGO) has been widely explored for cancer PTT due to its excellent photothermal capacity. However, rGO has some limitations, such as low colloidal stability and water insolubility, as well as absence of targeting capacity towards cancer cells. Herein, rGO produced by an environmentally- friendly method was functionalized with an amphiphilic polymer based on hyaluronic acid (HA-rGO) through hydrophobic-hydrophobic interactions for application in targeted breast cancer PTT. The functionalization improved rGO colloidal stability and cytocompatibility towards normal and breast cancer cells, as well as conferred targeting capacity towards CD44 overexpressing breast cancer cells. In addition, the photothermal effect mediated by HA-rGO upon laser irradiation reduced breast cancer cells’ viability. Overall, HA-rGO demonstrated a great potential for being used on-demand and selective treatment of breast cancer cells.
- Proton-assisted Two-electron Transfer in Natural Variants of Tetraheme Cytochromes from Desulfomicrobium Sp.Publication . Correia, Ilídio Joaquim Sobreira; Paquete, Catarina; Coelho, Ana; Almeida, Claudia; Catarino, Teresa; Louro, Ricardo; Frazão, Carlos; Saraiva, Lígia M.; Carrondo, Maria; Turner, David; Xavier, AntónioThe tetraheme cytochrome c3 isolated from Desulfomicrobium baculatum (DSM 1743)(Dsmb) was cloned, and the sequence analysis showed that this cytochrome differs in just three amino acid residues from the cytochrome c3 isolated from Desulfomicrobium norvegicum (Dsmn): (DsmnXXDsmb) Thr-37 → Ser, Val-45 → Ala, and Phe-88 → Tyr. X-ray crystallography was used to determine the structure of cytochrome c3 from Dsmb, showing that it is very similar to the published structure of cytochrome c3 from Dsmn. A detailed thermodynamic and kinetic characterization of these two tetraheme cytochromes c3 was performed by using NMR and visible spectroscopy. The results obtained show that the network of cooperativities between the redox and protonic centers is consistent with a synergetic process to stimulate the hydrogen uptake activity of hydrogenase. This is achieved by increasing the affinity of the cytochrome for protons through binding electrons and, reciprocally, by favoring a concerted two-electron transfer assisted by the binding of proton(s). The data were analyzed within the framework of the differences in the primary and tertiary structures of the two proteins, showing that residue 88, close to heme I, is the main cause for the differences in the microscopic thermodynamic parameters obtained for these two cytochromes c3. This comparison reveals how replacement of a single amino acid can tune the functional properties of energy-transducing proteins, so that they can be optimized to suit the bioenergetic constraints of specific habitats.
- In situ green reduced graphene oxide functionalized 3D printed scaffolds for bone tissue regenerationPublication . Cabral, C.S.D.; Miguel, Sónia; Diogo, Duarte Miguel De Melo; Louro, Ricardo; Correia, IlidioThe incorporation of reduced graphene oxide (rGO) nanomaterials into scaffolds structure can be explored to enhance the properties of these 3D matrices in bone regeneration applications. However, the weak water solubility and poor colloidal stability of rGO have hindered its incorporation in blends aimed to produce scaffolds by 3D printing. Furthermore, rGO is generally obtained by treating graphene oxide (GO) with hydrazine hydrate, which is a highly hazardous reducing agent. To overcome these problems, herein a novel environmentally-friendly method was developed to assemble 3D printed scaffolds incorporating rGO. Such was achieved through the in situ reduction mediated by l-Ascorbic acid of the GO already present on tricalcium phosphate/gelatin/chitosan scaffolds. The scaffolds functionalized with rGO through the in situ method (TGC_irGO) displayed enhanced wettability and improved mechanical properties without impairing their porosity when compared to their equivalents functionalized with GO and non-functionalized scaffolds (TGC_GO and TGC, respectively). Moreover, the TGC_irGO scaffolds displayed an improved calcium deposition at their surface and an enhanced alkaline phosphatase (ALP) activity, along 21 days of incubation. Additionally, scaffolds also displayed antimicrobial activity without compromising osteoblasts’ viability and proliferation. Such features reveal the potential of the TGC_irGO scaffolds for bone tissue regeneration applications.
- Functionalization of graphene family nanomaterials for application in cancer therapyPublication . Diogo, Duarte Miguel de Melo; Sousa, Ana Rita Lima; Alves, Cátia; Costa, Elisabete C.; Louro, Ricardo; Correia, Ilídio Joaquim SobreiraGraphene family nanomaterials’ (GFN) ability to interact with near-infrared light has propelled their application in cancer photothermal therapy. Furthermore, the graphitic lattice of GFN can adsorb different types of molecules, which has motivated their use in cancer drug delivery. However, the direct application of GFN in cancer therapy is severely hindered by their poor colloidal stability, sub-optimal safety, inefficient tumor uptake and non-selectivity towards cancer cells. To overcome these limitations, GFN have been functionalized with different types of materials. This review is focused on the different functionalizations used in the design of GFN aimed for application in cancer therapy, disclosing their role on surpassing the critical issues related to GFN-based therapies.
- Hyaluronic acid functionalized green reduced graphene oxide for targeted cancer photothermal therapyPublication . Sousa, Ana Rita Lima; Diogo, Duarte Miguel de Melo; Alves, Cátia; Costa, Elisabete C.; Ferreira, Paula; Louro, Ricardo; Correia, Ilídio Joaquim SobreiraReduced graphene oxide (rGO) nanomaterials display promising properties for application in cancer photothermal therapy (PTT). rGO is usually obtained by treating graphene oxide (GO) with hydrazine hydrate. However, this reducing agent contributes for the low cytocompatibility exhibited by rGO. Furthermore, rGO has a low water stability and does not show selectivity towards cancer cells. Herein, rGO attained using an environmentally-friendly method was functionalized with a novel hyaluronic acid (HA)-based amphiphilic polymer to be used in targeted cancer PTT. Initially, the green-reduction of GO with L-Ascorbic acid was optimized considering the near infrared absorption and the size distribution of the nanomaterials. Then, rGO was functionalized with the HA-based amphiphile. The functionalization of rGO improved its stability, cytocompatibility and internalization by CD44 overexpressing cells, which indicates the targeting capacity of this nanoformulation. Furthermore, the on-demand PTT mediated by HA-functionalized rGO induced cancer cells’ ablation, thereby confirming its potential for targeted cancer therapy.
- Biofunctionalized nanoparticles with pH-responsive and cell penetrating blocks for gene deliveryPublication . Gaspar, Vítor Manuel Abreu; Marques, João Filipe Gonçalves; Sousa, Fani; Louro, Ricardo; Queiroz, João; Correia, I.J.Bridging the gap between nanoparticulate delivery systems and translational gene therapy is a long sought after requirement in nanomedicine-based applications. However, recent developments regarding nanoparticle functionalization have brought forward the ability to synthesize materials with biofunctional moieties that mimic the evolved features of viral particles. Herein we report the versatile conjugation of both cell penetrating arginine and pH-responsive histidine moieties into the chitosan polymeric backbone, to improve the physicochemical characteristics of the native material. Amino acid coupling was confirmed by 2D TOCSY NMR and Fourier transform infrared spectroscopy. The synthesized chitosan–histidine–arginine (CH–H–R) polymer complexed plasmid DNA biopharmaceuticals, and spontaneously assembled into stable 105 nm nanoparticles with spherical morphology and positive surface charge. The functionalized delivery systems were efficiently internalized into the intracellular compartment, and exhibited remarkably higher transfection efficiency than unmodified chitosan without causing any cytotoxic effect. Additional findings regarding intracellular trafficking events reveal their preferential escape from degradative lysosomal pathways and nuclear localization. Overall, this assembly of nanocarriers with bioinspired moieties provides the foundations for the design of efficient and customizable materials for cancer gene therapy.
- In vitro characterization of 3D printed scaffolds aimed at bone tissue regenerationPublication . Boga, João Miguel Carvalho Freire; Miguel, Sónia P.; Diogo, Duarte Miguel de Melo; Mendonça, António; Louro, Ricardo; Correia, Ilídio Joaquim SobreiraThe incidence of fractures and bone-related diseases like osteoporosis has been increasing due to aging of the world’s population. Up to now, grafts and titanium implants have been the principal therapeutic approaches used for bone repair/regeneration. However, these types of treatment have several shortcomings, like limited availability, risk of donor-to-recipient infection and tissue morbidity. To overcome these handicaps, new 3D templates, capable of replicating the features of the native tissue, are currently being developed by researchers from the area of tissue engineering. These 3D constructs are able to provide a temporary matrix on which host cells can adhere, proliferate and differentiate. Herein, 3D cylindrical scaffolds were designed to mimic the natural architecture of hollow bones, and to allow nutrient exchange and bone neovascularization. 3D scaffolds were produced with tricalcium phosphate (TCP)/alginic acid (AA) using a Fab@home 3D printer. Furthermore, graphene oxide (GO) was incorporated into the structure of some scaffolds to further enhance their mechanical properties. The results revealed that the scaffolds incorporating GO displayed greater porosity, without impairing their mechanical properties. These scaffolds also presented a controlled swelling profile, enhanced biomineralization capacity and were able to increase the Alkaline Phosphatase (ALP) activity. Such characteristics make TCP/AA scaffolds functionalized with GO promising 3D constructs for bone tissue engineering applications.
- Environmentally-friendly reduced graphene oxide functionalized with hyaluronic acid for targeted cancer photothermal therapyPublication . Sousa, Ana Rita Lima; Diogo, Duarte de Melo; Alves, Cátia; Costa, Elisabete; Ferreira, Paula; Louro, Ricardo; Mendonça, António; Correia, I.J.Reduced Graphene Oxide (rGO) is one of the most promising nanomaterials for cancer photothermal therapy (PTT) due to its high near infrared (NIR) absorption. However, the rGO producing methods uses dangerous reducing agents, resulting in poor biocompatibility. Additionally, rGO also displays poor colloidal stability and is unable to target cancer cells. These limitations can be improved by using environmentally-friendly reduction methods and by functionalizing this nanomaterial with amphiphilic polymers. In this work, the production of reduced Graphene Oxide (rGO) rGO was performed by using an environmentally-friendly method (reduction with L-ascorbic Acid (LAA)). Then, the obtained rGO was functionalized with an amphiphilic polymer based on hyaluronic acid (HA-g-PMAO) for application in CD44-targeted breast cancer PTT