O4 - Exploring the biological properties and regenerative potential of biomaterials using cell culture models

Life expectancy has improved signifcantly and, along with the declining birthrate, has contributed to the aging of populations, especially in industrialized countries. Alas, aging is intrinsically associated with the incidence of health problems including bone and tooth loss that require suitable solutions to support the quality of life. To meet these demands, signifcant research eforts have been undertaken to develop novel biomaterials, both orthopedic and dental implants. The feld of biomaterials for bone tissue engineering is increasingly evolving. The most recent generations of biomaterials have increasingly more activity and interaction with the biological environment and stimulate the regeneration of functional tissue. Natural polymers and compounds have been combined with each other to improve workability and are strategically integrated with ceramics or bioactive glasses to reinforce the structure of the fnal system, thus producing composites with a better mechanical performance. Our research group has been focused on the biological characterization of diferent added-value materials and composites, namely by evaluating their antimicrobial, biocompatibility, and regenerative properties. Some of our recent work results allowed us to conclude that marine fungal extracts, as well as sol–gel-derived bioactive glass nanoparticles, have inhibitory efects on the growth of C. albicans and E. faecalis (main pathogens in persistent root canal infections). Additionally, we have characterized cuttlefsh bone powders for endodontic applications. We are also committed to developing strategies for monitoring cell response to these biomaterials at the molecular level that could be used to follow infammation and osteoconduction.info:eu-repo/semantics/publishedVersio

The effect of deep ocean currents on ocean- bottom seismometers records

Ocean-bottom seismometers (OBSs) are usually deployed for seismological investigations, but these objectives are impaired by noise resulting from the ocean environment. We split the OBS-recorded seismic noise into three bands: short periods, microseisms and long periods, also known as tilt noise. We show that bottom currents control the first and third bands, but these are not always a function of the tidal forcing. Instead, we suggest that the ocean bottom has a flow regime resulting from two possible contributions: the permanent low-frequency bottom current and the tidal current. The recorded noise displays the balance between these currents along the entire tidal cycle, between neap and spring tides. In the short-period noise band, the ocean current generates harmonic tremors corrupting seismic dataset records. We show that, in the investigated cases, the harmonic tremors result from the interaction between the ocean current and mechanical elements of the OBS that are not essential during the sea bottom recording and thus have no geological origin. The data from a new broadband OBS type, designed and built at Instituto Dom Luiz (IDL – University of Lisbon)/Centre of Engineering and Product Development (CEIIA), hiding non-essential components from the current flow, show how utmost harmonic noise can be eliminated.</p

Photodynamic inactivation of phage Phi6 as SARS-CoV-2 model in wastewater disinfection: effectivity and safety

The past 2 years have been marked by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. This virus is found in the intestinal tract and reaches the wastewater system, and, consequently, the natural receiving water bodies, and inappropriate or/and inefficient WW treatment is a means of contamination. In the present work, we used a SARS-CoV-2 model—the phage Phi6—to evaluate its survival under different environmental conditions (pH, temperature, salinity, solar, and UV-B irradiation). Then, we tested the efficiency of photodynamic inactivation (PDI) as a WW disinfection alternative method, and, additionally, the impact on the cultivable native marine microorganisms of the PDI-treated WW was evaluated.info:eu-repo/semantics/publishedVersio

Photoinactivation of phage phi6 as a SARS-CoV-2 model in wastewater: evidence of efficacy and safety

The last two years have been marked by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. This virus is found in the intestinal tract; it reaches wastewater systems and, consequently, the natural receiving water bodies. As such, inefficiently treated wastewater (WW) can be a means of contamination. The currently used methods for the disinfection of WW can lead to the formation of toxic compounds and can be expensive or inefficient. As such, new and alternative approaches must be considered, namely, photodynamic inactivation (PDI). In this work, the bacteriophage ϕ6 (or, simply, phage ϕ6), which has been used as a suitable model for enveloped RNA viruses, such as coronaviruses (CoVs), was used as a model of SARS-CoV-2. Firstly, to understand the virus’s survival in the environment, phage ϕ6 was subjected to different laboratory-controlled environmental conditions (temperature, pH, salinity, and solar and UV-B irradiation), and its persistence over time was assessed. Second, to assess the efficiency of PDI towards the virus, assays were performed in both phosphate-buffered saline (PBS), a commonly used aqueous matrix, and a secondarily treated WW (a real WW matrix). Third, as WW is generally discharged into the marine environment after treatment, the safety of PDI-treated WW was assessed through the determination of the viability of native marine water microorganisms after their contact with the PDI-treated effluent. Overall, the results showed that, when used as a surrogate for SARS-CoV-2, phage ϕ6 remains viable in different environmental conditions for a considerable period. Moreover, PDI proved to be an efficient approach in the inactivation of the viruses, and the PDI-treated effluent showed no toxicity to native aquatic microorganisms under realistic dilution conditions, thus endorsing PDI as an efficient and safe tertiary WW disinfection method. Although all studies were performed with phage ϕ6, which is considered a suitable model of SARS-CoV-2, further studies using SARS-CoV-2 are necessary; nevertheless, the findings show the potential of PDI for controlling SARS-CoV-2 in WW.info:eu-repo/semantics/publishedVersio

Antioxidant potential of two red seaweeds from the Brazilian coasts

In this work, in vitro antioxidant activity of two Brazilian red seaweeds, Gracilaria birdiae and Gracilaria cornea, was characterized. The total phenolic content, the radical-scavenging activity and the antioxidant activity were determined in two solvent extracts of the algae. Liquid chromatography mass spectrometry (LC MS/MS) allowed identification of important antioxidant compounds. The ethanol extract of G. birdiae was found to have the highest value of total phenolic content: 1.13 mg of gallic acid equiv (GAE)/g of extract.The radical-scavenging activity of G. birdiae and G. cornea extracts has been evaluated at different extract concentrations; the IC50 values of ethanolic extracts of G. cornea and G. birdiae were 0.77 and 0.76mgmL 1, respectively, while formethanolic extracts, the IC50 values of G. cornea and G. birdiae were 0.86 and 0.76mgmL 1, respectively. The antioxidant activities of these two seaweeds’ extracts as assessed by the ß-carotene linoleic acid assay were equally high, achieving values of ß-carotene oxidation inhibition of up to 40%. Finally, in the methanolic extracts, LC MS/MS allowed identification in both algae of two important antioxidants: apigenin and gallic acid.B.W.S.S. is the recipient of a fellowship from the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil) M.A.C. and J.T.M. are recipients of fellowships from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) (SFRH/BD/23897/2005 and SFRH/BD/32566/2006, respectively)

A study of wastewater disinfection with photodynamic treatment and its ecotoxicological effects

info:eu-repo/semantics/publishedVersio

P9 - Antimicrobial properties and bioactivity potential of smart nanoparticles for dental applications

Tooth decay is one of the greatest causes of tooth loss in the world. This not only afects the patient’s quality of life but also carries an economic burden associated with the need for multiple reinterventions. Endodontic treatment aims to preserve teeth by cleaning, disinfecting and flling/sealing the root canal. Despite the high success rate of endodontic treatment, failures do occur in a large number of cases. Several new biomaterials for dentistry have been developed, however their bioactivity is often misunderstood. Our work focuses on the biological characterization of novel bioactive glass nanoparticles, including the evaluation of their antimicrobial and biocompatibility properties. Candida albicans (ATCC 11225) and Enterococcus faecalis (ATCC 29212) were included to evaluate the antimicrobial potential by the drop plate method [1]. The cytotoxicity was tested using the MC3T3-E1 cell line, through the resazurin reduction assay. The novel bioactive glass nanoparticles demonstrated antimicrobial activity against C. albicans and E. faecalis, being able to inhibit their growth but also, in some incubation times, decreased the survival of these microorganisms. After 24 h of incubation of MC3T3-E1 osteoblast cells with bioactive glass nanoparticles conditioned medium, around 48% cell viability was achieved. These novel bioactive glass nanoparticles have shown promising properties which may fnd applications on diferent areas of clinical dentistry.info:eu-repo/semantics/publishedVersio

A study of wastewater disinfection with photodynamic treatment and its ecotoxicological effects

Viruses have higher mutation rates when compared with other microorganisms, particularly RNA viruses [1]. The higher mutation rate promotes the development of resistance to traditional antivirals, establishing a resistance behavior in viruses populations [1]. RNA viruses in wastewater (WW) have already been reported, leading to potential public health risks [2]. Wastewater treated with conventional antimicrobial approaches (tertiary WW treatments) like UV light, chlorine, and ozone can lead to viruses mutations and the formation of toxic by-products harmful to humans and the environment [3]. All this, highlights the inevitability to provide alternative WW disinfection techniques. Antimicrobial Photodynamic treatment (PDt), an approach based on the action of reactive oxygen species (ROS), is being considered a promising alternative to viruses inactivation without the generation of viral mutations or toxic by-products [4,5]. This study evaluated the efficiency of PDt in the inactivation of bacteriophage Phi6 (RNA-viruses model) in real WW. PDt assays were carried out in a buffer solution (PBS, as a controlled medium) and in WW (after secondary treatment) with Methylene Blue (MB) as photosensitizer (PS), and a low energy consuming light source (LED). The disinfection protocol developed with MB resulted in an efficient inactivation of the bacteriophage Phi6, both in PBS and in the real WW. Considering that treated effluents are released into the environment, the acute toxicity of PDttreated WW to the model organism Daphnia magna was also evaluated during a 48h exposure to the PDt-treated WW with MB. In this communication it will be present and discuss the PDt protocol developed to photoinactivate the model RNAvirus bacteriophage Phi6 and the preliminary results of the acute toxicity of PDt-treated WW in Daphnia magna model.info:eu-repo/semantics/publishedVersio

Photoinactivation of bacterial and fungal planktonic/biofilm forms using the combination of a porphyrinic formulation with potassium iodide

Antimicrobial photodynamic therapy (aPDT) is a promising approach against multidrug-resistant microorganisms. In this work, we accessed the photodynamic efficiency of an affordable formulation composed of five cationic porphyrins (FORM) and its combined effect with potassium iodide (KI) on a large spectrum of microorganisms. For this purpose, the aPDT assays were conducted with FORM alone and FORM + KI on planktonic and biofilm forms of Gram(+) (Staphylococcus aureus) and Gram(−) (Escherichia coli) bacteria and of the yeast Candida albicans. The results obtained indicate that FORM, at low concentrations (0.5–5.0 μM), had an efficient photodynamic action on the planktonic forms of E. coli, S. aureus, and C. albicans. Moreover, the combination of FORM with KI improved the photodynamic action of this PS, promoting microbial inactivation with lower PS concentrations and treatment time. The combination of FORM + KI was also extremely efficient in the destruction of bacterial and fungal biofilms. This outstanding effect may be due to the action of longer-lived iodine reactive species produced by the reaction of KI with the ROS generated by FORM during the aPDT treatment.info:eu-repo/semantics/publishedVersio