Browsing by Author "Fernandes, M. H."
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- Cytotoxicity of marine cyanobacteria extracts on osteosarcoma cellsPublication . Costa-Rodrigues, João; Costa, M. M.; Costa, S.; Garcia, M.; Fernandes, M. H.; Vasconcelos, V.; Barros, Piedade; Martins, RosárioMarine cyanobacteria have been identified as a rich source of secondary metabolites with potential pharmacological applications. Anti-inflammatory, antibacterial and anticancer activities are some examples of properties described for cyanobacteria compounds, being the cytoxicity against cancer cell lines one of the most documented. The Laboratory of Ecotoxicology Genomics and Evolution (LEGE) — CIIMAR, Porto, Portugal, possesses a large collection of cyanobacteria strains isolated from the Portuguese coast. In order to investigate the interest of genera such as Cyanobium, Synechocystis, Synechococcus, Leptolyngbya and Pseudoanabaena which are genera that have been largely overlooked in terms of bioactivity, we have been screening their ability to induce cytotoxicity on human cancer cell lines. Assays have been conducted with a crude extract obtained by a dichloromethane and methanol extraction of freeze dried biomass and three fractions obtained using Si column chromatography with a gradient from 100% hexane, to 100% ethyl acetate to 100% methanol. The cytotoxicity of cyanobacteria crude extract and fractions has been evaluated by the MTT assay at 24, 48 and 72 h. Here we present the results concerning the cytotoxicity of 24 cyanobacteria strains on the osteosarcoma cell line MG63. The results show both inhibitory and stimulatory effects on cell growth within the same cyanobacteria strain. However, five cyanobacteria strains were found to induce a decrease in cell viability that reached the 80% within the ethyl acetate fraction, which makes this fraction interesting for the isolation and characterization of new bioactive compounds.
- Osteoclastogenic differentiation of human precursor cells over micro- and nanostructured hydroxyapatite topographyPublication . Costa-Rodrigues, Joao; Carmo, S.; Perpétuo, I. P.; Monteiro, F. J.; Fernandes, M. H.Background: Surface topography is a key parameter in bone cells–biomaterials interactions. This study analyzed the behavior of human osteoclast precursor cells cultured over three hydroxyapatite (HA) surfaces ranging from a micro- to nanoscale topography. Methods: HA surfaces were prepared with microsized HA particles, at 1300 °C (HA1), andwith nanosized HA particles at 1000 °C (HA2) and 830 °C (HA3). Human osteoclast precursorswere cultured in the absence or presence of M-SCF and RANKL. Results: HA surfaces had similar chemical composition, however, HA1 and HA3 presented typical micro- and nanostructured topographies, respectively, and HA2 profile was between those of HA1 and HA3. The decrease on the average grain diameter to the nanoscale range (HA3)was accompanied by an increase in surface area, porosity and hydrophilicity and a decrease in roughness. Compared to HA1 surface, HA3 allowed a lower osteoclastic adhesion, differentiation and function. Differences in the cell response appeared to be associated with the modulation of relevant intracellular signaling pathways. Conclusions: The decrease in HA grain size to a biomimetic nanoscale range, appears less attractive to osteoclastic differentiation and function, compared to the HA microsized topography. General significance: This observation emphasizes the role of surface topography in designing advanced biomaterials for tailored bone cells response in regenerative strategies.
- Sarcosine oxidase composite screen-printed electrode for sarcosine determination in biological samplesPublication . Rebelo, Tânia S. C. R.; Pereira, Carlos M.; Sales, M. Goreti F.; Noronha, João P.; Costa-Rodrigues, João; Silva, Fernando; Fernandes, M. H.Prostate Cancer (PCa) is the most common form of cancer in men in Europe with a 61.4 % incidence among all cancer cases and a 12.1 % mortality [1] and, therefore, its early detection is fundamental for increasing the survival rate. Currently, diagnosis and management of patients with PCa is only based on the determination of the biomarker Prostate Specific Antigen (PSA). However, the method used for PCa detection has poor sensitivity and specificity, leading to false negative and false positive test results and many patients are sent to unnecessary biopsy procedures [2]. Therefore, there is a need to seek for new biomarkers and more effective screening. In this work, a biosensor device was developed for the quantification of sarcosine via electrochemical detection of H2O2 (at 0.6 V) generated from the catalyzed oxidation of sarcosine. The detection was carried out after the modification of carbon screen printed electrodes (SPEs) by immobilization of sarcosine oxidase (SOX) on the electrode surface. The strategies used herein included the activation of the carbon films by an electrochemical step and the formation of an NHS/EDAC layer to bond the enzyme to the electrode, the use of metallic or semiconductor nanoparticles layer previously or during the enzyme immobilization. In order to improve the sensor stability and selectivity a polymeric layer with extra enzyme content was further added. The proposed methodology for the detection of sarcosine allowed obtaining a limit of detection (LOD) of 1.6x10-5 mM, using a linear concentration range between 1x10-5 and 1x10-4 mM. The biosensor was successfully applied to the analysis of sarcosine in urine samples.