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Zinc pthalocyanine loaded poly (lactic acid) nanoparticles by double emulsion methodology for photodynamic therapy against 9 L/LacZ gliosarcoma cells
(Taylor & Francis Group) Oliveira Junior, Benedito Marcio de; Teodoro, Jéssica Beatriz Miranda; Ambrósio, Jéssica Aparecida Ribeiro; Gonçalves, Érika Peterson; Beltrame Junior, Milton; Marcolino, Luciana Maria Cortez; Pinto, Juliana Guerra; Ferreira-Strixino, Juliana; Simioni, Andreza Ribeiro
Development delivery systems, such as nanoparticles, represent a growing area in biomedical research. Nanoparticles (NP) were prepared using a double-emulsion method to load zinc(II) phthalocyanine (ZnPc). NP were obtained using poly (lactic acid) (PLA). ZnPc is a second generation of photosensitizer used in photodynamic therapy (PDT). ZnPc loaded PLA nanoparticles (NPLAZnPc) were prepared by double-emulsion method, characterized and available in cellular culture. The mean nanoparticle size presented particle size was 384.7 ± 84.2 nm with polydispersity index (PDI) of 0.150 ± 0.015, and the encapsulation efficiency was of 83%. The nanoparticle formulations presented negative zeta potential values (27.5 ± 1.0 mV), explaining their colloidal stability. ZnPc loaded nanoparticles maintain its photophysical behavior after encapsulation. Photosensitizer release from nanoparticles was sustained over 168 h with a biphasic ZnPc release profile. An in vitro phototoxic effect in range of 80% was observed in 9 L/ LacZ gliosarcoma cells at laser light doses (10 J cm2) with 3.0 mg mL1 of NPLA-ZnPc. All the physical–chemical, photophysical and photobiological measurements performed allow us to conclude that ZnPc loaded PLGA nanoparticles is a promising drug deliverysystem for PDT.
Synthesis and characterization of photosensitive gelatin-based hydrogels for photodynamic therapy in HeLa-CCL2 cell line
(Elsevier) Ambrósio, Jéssica Aparecida Ribeiro; Pinto, Bruna Cristina dos Santos; Marmo, Vitor Luca Moura; Santos, Kennedy Wallace dos; Beltrame Junior, Milton; Pinto, Juliana Guerra; Ferreira-Strixino, Juliana; Raniero, Leandro José; Simioni, Andreza Ribeiro
Background: Hydrogel systems are increasingly gaining visibility involving biomedicine, tissue engineering, environmental treatments, and drug delivery systems. These systems have a three-dimensional network composition and high-water absorption capacity, are biocompatible, allowing them to become an option as photosensitizer carriers (PS) for applications in Photodynamic Therapy (PDT) protocols. Methods: A nanohydrogel system (NAHI), encapsulated with chloroaluminium phthalocyanine (ClAlPc) was synthesized for drug delivery.. NAHI was synthesized using gelatin as based polymer by the chemical cross-linking technique. The drug was encapsulated by immersing the hydrogel in a 1.0 mg.mL􀀀 1 ClAlPc solution. The external morphology of NAHI was examined by scanning electron microscopy (SEM). The degree of swelling of the synthesized system was evaluated to determine the water absorption potential. The produced nanohydrogel system was characterized by photochemical, photophysical and photobiologial studies. Results: The images from the SEM analysis showed the presence of three-dimensional networks in the formulation. The swelling test demonstrated that the nanohydrogel freeze-drying process increases its water holding capacity. All spectroscopic results showed excellent photophysical parameters of the drug studied when served in the NAHI system. The incorporation efficiency was 70%. The results of trypan blue exclusion test have shown significant reduction (p < 0.05) in the cell viability for all groups treated with PDT, in all concentrations tested. In HeLa cells, PDT mediated by 0,5 mg.mL􀀀 1 ClAlPc encapsulated in NAHI showed a decrease in survival close to 95%. In the internalization cell study was possible to observe the internalization of phthalocyanine after one hour of incubation, at 37 ◦C, with the the accumulation of PS in the cytoplasm and inside the nucleus at both concentrations tested. Conclusions: Given the peculiar performance of the selected system, the resulting nanohydrogel is a versatile platform and display potential applications as controlled delivery systems of photosensitizer for photodynamic therapy application.
Synthesis, characterization, and evaluation of chloroaluminium phthalocyanine incorporated in poly(ε-caprolactone) nanoparticles for photodynamic therapy
(Elsevier) Pinto, Bruna Cristina dos Santos; Ambrósio, Jéssica Aparecida Ribeiro; Marmo, Vitor Luca Moura; Pinto, Juliana Guerra; Raniero, Leandro José; Ferreira-Strixino, Juliana; Simioni, Andreza Ribeiro; Beltrame Junior, Milton
Background: The use of nanotechnology has been widely used in biomedical science, including orthopedic implants, tissue engineering, cancer therapy and drug elution from nanoparticle systems, such as poly-caprolactone (PCL) nanoparticles, which stand out mainly for their biocompatibility, being considered as effective carriers for photosensitizing drugs (PS) in photodynamic therapy (PDT) protocols. Methods: This manuscript describes the synthesis and characterization of PCL nanoparticles for controlled release of the drug chloro-aluminum phthalocyanine (ClAlPc) as a photosensitizer for application in PDT. The PCL-ClAlPc nanoparticles were developed by the nanoprecipitation process. The structure and morphology of the nanoparticles were studied with scanning electron microscopy (SEM) and with Fourier transform infrared (FTIR). The size of nanomaterials was studied using the Dynamic Light Scattering (DLS) method. Photophysical and photochemical characterizations were performed. Subsequently, photobiological studies were also used to characterize the system. Results: The nanoparticles had an average diameter of 384.7 ± 138.6 nm and a polydispersity index of 0.153. SEM analysis revealed that the system formed a spherical shape typical of these delivery systems. Charging efficiency was 82.1% ± 1.2%. The phthalocyanine-loaded PCL nanoparticles maintained their photophysical behavior after encapsulation. Cell viability was determined after the dark toxicity test, and it was possible to observe that there was no evidence of toxicity in the dark, for all concentrations tested. The assay also revealed that adenocarcinoma cells treated with free ClAlPc and in the nanoformulation showed 100% cell death when subjected to PDT protocols. The intracellular location of the photosensitizer indicated a high potential for accumulation in the cytoplasm and nucleus. Conclusions: From the photophysical, photochemical and photobiological analyzes obtained, it was possible to observe that the development of PCL nanoparticles encapsulated with ClAlPc, by the nanoprecipitation method was adequate and that the in vivo release study is efficient to reduce the release rate and attenuate the burst of PS loaded on PCL nanoparticles. The results reinforce that the use of this system as drug delivery systems is useful in PDT protocols.
Zinc phthalocyanine tetrasulfonate-loaded polyelectrolytic PLGA nanoparticles for photodynamic therapy applications
(Elsevier) Toledo, Maria Cristina Modesto Clementino de; Abreu, Alexandro da Silva; Carvalho, Janicy Arantes; Ambrósio, Jéssica Aparecida Ribeiro; Godoy, Daniele da Silva; Pinto, Bruna Cristina dos Santos; Beltrame Junior, Milton; Simioni, Andreza Ribeiro
Background: Photodynamic Therapy (PDT) is a modality for the treatment of neoplastic tissues, which is based on the administration of a phototherapeutic agent and light irradiation at an appropriate wavelength, aiming to locate and destroy the target cell with the formation of reactive oxygen species. Nanoencapsulation technology presents itself as a tool for incorporation of bioactive substances aiming to improve their solubility in physiological environment, obtain a longer circulation time in the organism, administration of lower dosages and the minimization of side effects. The present work aimed at the development of poly (lactic acid-glycolic acid) (PLGA) nanoparticles coated with polyelectrolyte film layers for encapsulating zinc phthalocyanine tetrasulfonated (ZnPcSO4) as a bioactive substance model. Methods: PLGA nanoparticles were produced by the double emulsion/solvent evaporation technique and polyelectrolytic coating was performed using polyalkylamine hydrochloride (PAH) as a weak polycation and poly (4- styrene sulfonate) (PSS) as a strong polyanion by layer-by-layer self-assembly technique (known as layer-by-layer-LbL). The nanoparticulate system was studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by classical MTT assay. Results: The polyelectrolytic PLGA nanoparticles had an average diameter of 384.7 ± 138.6 nm, restricted distribution size with a polydispersity index. The obvious change in zeta potential indicates successful alternation in polycation (PAH) and polyanion (PSS) deposition directly in PLGA nanoparticles. Scanning electron microscopy (SEM) analysis showed that the formed system had morphology spherical, typical of these release systems. The loading efficiency was 82.1 % ± 1.2 %. The polyelectrolytic nanoparticles loaded with phthalocyanine maintained their photophysical behavior after encapsulation. Cell viability was determined, obtaining 90 % cell death. Conclusions: Therefore, the presented work depicts ZnPcSO4-loaded polyelectrolytic PLGA nanoparticles as a promise drug delivery system for phototherapeutic agent, which are thus expected to have superior therapeutic efficiency than free drug.
Crystalline structure, morphology, and adherence of thick TiO2 films grown on 304 and 316L stainless steels by atomic layer deposition
(MDPI) Marques, Vagner Eduardo Caetano; Manfroi, Lucas Augusto; Vieira, Angela Aparecida; Pereira, André Luis de Jesús; Marques, Francisco das Chagas; Vieira, Lúcia
Titanium dioxide (TiO2) thin films are widely used in transparent optoelectronic devices due to their excellent properties, as well as in photocatalysis, cosmetics, and many other biomedical applications. In this work, TiO2 thin films were deposited onto AISI 304 and AISI 316L stainless steel substrates by atomic layer deposition, followed by comparative evaluation of the mixture of anatase and rutile phase by X-ray diffraction, Raman maps, morphology by SEM-FEG-AFM, and adhesion of the films on the two substrates, aiming to evaluate the scratch resistance. Raman spectroscopy mapping and X-ray diffraction with Rietveld refinement showed that the films were composed of anatase and rutile phases, in different percentages. Scratch testing using a diamond tip on the TiO2 film was employed to evaluate the film adherence and to determine the friction coefficient, with the results showing satisfactory adherence of the films on both substrates.
Use of an inexpensive carbon source for the production of a cellulase enzyme complex from Penicillium ucsense S1M29 and enzymatic hydrolysis optimization
(Biofuels Bioproducts & Biorefining) Lima, Deise Juliana da Silva; Couto, Rafaela; Souza, Jucara Cristina Pereira; Camassola, Marli; Fontana, Roselei C.; Dillon, Aldo Jose; Pradella, Jose Geraldo da Cruz
The high cost of cellulolytic enzyme complexes (CECs) has been a significant impediment to the commercial production of bioproducts from lignocellulose biomass. This study aimed to develop a cost-effective CEC derived from Penicillium ucsense (former Penicillium echinulatum), utilizing diverse forms of pretreated sugarcane bagasse as the primary carbon/inductor source. Among the different pretreatments used, the hydrothermal pretreatment followed by NaOH delignification (BHD) produced higher FPase and xylanase activities (4.5 FPU mL–1 and 120 IU mL–1) in bioreactor experiments at 20 g BHD L–1 initial concentration. A batch-mode assay conducted across a range of initial carbon source (5 to 60 g L–1) confirmed the highest FPase activity (4.0 to 5.0 FPU mL–1 at 120 h), in the range of 20–40 g BHD L–1. During these assays the agitation rate, controlled by dissolved O2, tended to stabilize at lower levels, indicating substrate limitation. Conversely, higher initial carbon source concentrations led to an excess of glucose, likely triggering carbon catabolite repression and inhibiting cellulase production. This insight prompted the development of a controlled pulsed fed-batch strategy, resulting in FPase activity of 11 FPU mL–1 at 220 h using 90 g L–1 BHD controlled fed into the bioreactor. An enzymatic hydrolysis procedure using the generated CEC was also optimized using a central composite rotational design (CCRD). The optimized enzyme hydrolysis conditions achieved a reducing sugar concentration of 80.9 g L–1 in 48 h using 170 g L–1 of BHD as the substrate at a ratio of 15 FPU of enzyme substrate per g of BHD. A preliminary economic assessment demonstrated that, for a first- and second-generation (1G + 2G) ethanol biorefinery, the cost contribution of enzymes would be about US$0.2/L of biofuel. In conclusion, an efficient and highly productive procedure was developed successfully for the production of a CEC. It was particularly effective for the enzymatic hydrolysis of pretreated sugarcane bagasse.
Biocomposite macrospheres based on strontium-bioactive glass for application as bone fillers
(American Chemical Society) Oliveira, Ivone Regina de; Gonçalves, Isabela dos Santos; Santos, Kennedy Wallace dos; Lança, Maria Carmo; Vieira, Tânia; Silva, Jorge Carvalho; Cengiz, Ibrahim Fatih; Reis, Rui Luís; Oliveira, Joaquim Miguel; Borges, João Paulo Miranda Ribeiro
Traditional bioactive glass powders are typically composed of irregular particles that can be packed into dense configurations presenting low interconnectivity, which can limit bone ingrowth. The use of novel biocomposite sphere formulations comprising bioactive factors as bone fillers are most advantageous, as it simultaneously allows for packing the particles in a 3-dimensional manner to achieve an adequate interconnected porosity, enhanced biological performance, and ultimately a superior new bone formation. In this work, we develop and characterize novel biocomposite macrospheres of Sr-bioactive glass using sodium alginate, polylactic acid (PLA), and chitosan (CH) as encapsulating materials for finding applications as bone fillers. The biocomposite macrospheres that were obtained using PLA have a larger size distribution and higher porosity and an interconnectivity of 99.7%. Loose apatite particles were observed on the surface of macrospheres prepared with alginate and CH by means of soaking into a simulated body fluid (SBF) for 7 days. A dense apatite layer was formed on the biocomposite macrospheres’ surface produced with PLA, which served to protect PLA from degradation. In vitro investigations demonstrated that biocomposite macrospheres had minimal cytotoxic effects on a human osteosarcoma cell line (SaOS-2 cells). However, the accelerated degradation of PLA due to the degradation of bioactive glass may account for the observed decrease in SaOS-2 cells viability. Among the biocomposite macrospheres, those composed of PLA exhibited the most promising characteristics for their potential use as fillers in bone tissue repair applications.
Development and characterization of ceramic-polymeric hybrid scaffolds for bone regeneration: incorporating of bioactive glass BG-58S into PDLLA matrix
(Taylor & Francis) Aguiar, Veronica Cristina Pêgo Fiebig; Bezerra, Rayssa do Nascimento; Santos, Kennedy Wallace dos; Gonçalves, Isabela dos Santos; Costa, Karen Julie Santos Grancianinov; Lauda, Diogo Ponte; Campos, Tiago Moreira Bastos; Prado, Renata Falchete do; Vasconcellos, Luana Marotta Reis de; Oliveira, Ivone Regina de
In recent years, there has been a notable surge of interest in hybrid materials within the biomedical field, particularly for applications in bone repair and regeneration. Ceramic-polymeric hybrid scaffolds have shown promising outcomes. This study aimed to synthesize bioactive glass (BG-58S) for integration into a bioresorbable poly- meric matrix based on PDLLA, aiming to create a bioactive scaffold featuring stable pH levels. The synthesis involved a thermally induced phase separation process followed by lyophilization to ensure an appropriate porous structure. BG-58S characterization revealed vitreous, bioactive, and mesoporous structural properties. The scaffolds were analyzed for morphology, interconnectivity, chemical groups, porosity and pore size distribution, zeta potential, pH, in vitro degradation, as well as cell viability tests, total protein content and mineralization nodule production. The PDLLA scaffold displayed a homogeneous morphology with interconnected mac- ropores, while the hybrid scaffold exhibited a heterogeneous mor- phology with smaller diameter pores due to BG-58S filling. The hybrid scaffold also demonstrated a pH buffering effect on the polymer surface. In addition to structural characteristics, degrada- tion tests indicated that by incorporating BG-58S modified the acidic degradation of the polymer, allowing for increased total pro- tein production and the formation of mineralization nodules, indi- cating a positive influence on cell culture.
Scratch and wear behaviour of Co-Cr-Mo alloy in ringer’s lactate solution
(MDPI) Silva, Raimundo; Santos, Marcos Dantas dos; Madureira, Rui; Soares, Rui; Neto, Rui; Vieira, Angela Aparecida; Gonçalves, Polyana Alves Radi; Leite, Priscila Maria Sarmeiro Corrêa Marciano; Vieira, Lúcia; Viana, Filomena
Cobalt–chromium–molybdenum (Co-Cr-Mo) alloy is a material recommended for biomedical implants; however, to be suitable for this application, it should have good tribological properties, which are related to grain size. This paper investigates the tribological behaviour of a Co-Cr-Mo alloy produced using investment casting, together with electromagnetic stirring, to reduce its grain size. The samples were subjected to wear and scratch tests in simulated body fluid (Ringer’s lactate solution). Since a reduction in grain size can influence the behaviour of the material, in terms of resistance and tribological response, four samples with different grain sizes were produced for use in our investigation of the behaviour of the alloy, in which we considered the friction coefficient, wear, and scratch resistance. The experiments were performed using a tribometer, with mean values for the friction coefficient, normal load, and tangential force acquired and recorded by the software. Spheres of Ti-6Al-4V and 316L steel were used as counterface materials. In addition, to elucidate the influence of grain size on the mechanical properties of the alloy, observations were conducted via scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD). The results showed changes in the structure, with a reduction in grain size from 5.51 to 0.79 mm. Using both spheres, the best results for the friction coefficient and wear volume corresponded to the sample with the smallest grain size of 0.79 mm. The friction coefficients obtained were 0.37 and 0.45, using the Ti-6Al-4V and 316L spheres, respectively. These results confirm that the best surface finish for Co-Cr-Mo alloy used as a biomedical implant is one with a smaller grain size, since this results in a lower friction coefficient and low wear.
Corrosion performance of polypyrrole-bilayer coating on carbon steel
(Springer Nature) Cho, Liu Yao; Guiotti, Luciano Grande; Liu, Andréa Santos
Polypyrrole doped with phosphoric acid was electrochemically synthesized on carbon steel from acetonitrile medium, and then a coating of polypyrrole doped with a long carbon chain acid, dodecylbenzenesulfonic acid or lauric acid, was electrodeposited to form a bilayer. The more protective performance of the bilayers in relation to monolayers was explained in terms of adherence and low porous, as confirmed by scanning electron microscopy. The corrosion perfor- mance was also confirmed by electrochemical measurements of open-circuit potential, potentiodynamic polarization curves and electrochemical impedance spectroscopy in chloride solution. The polarization experiments indicated that the corrosion potential values for polypyrrole-bilayer-coated steel were shifted to the positive direction in relation to uncoated carbon steel, indicating anodic protection. Tafel plots also indicated that the anodic current densities were smaller for steel coated by polypyrrole-bilayer. In addition, the electrochemical impedance data showed that the charge transfer resistance values are associated with the resistance to electron exchange between the metal and the coating, and depend on the type of long carbon chain dopant used in the outer-layer. Thus, the suggested mechanism to explain the protection of carbon steel surfaces against corrosion was associated to the passivation and barrier effect of the polypyrrole-bilayer.
Hydroxyapatite microspheres used as a drug delivery system for gliosarcoma strain 9l/Lacz treatment by photodynamic therapy protocols
(Elsevier) Ambrósio, Jéssica Aparecida Ribeiro; Marmo, Vitor Luca Moura; Gonçalves, Érika Peterson; Pinto, Juliana Guerra; Ferreira-Strixino, Juliana; Raniero, Leandro José; Beltrame Junior, Milton; Simioni, Andreza Ribeiro
Background: Hydroxyapatite (HAp) presents similarities with the human bone structure and presents properties such as biodegradability, biocompatibility, and osteoconductivity, which favors its use in prostheses implants and enables its use as a vehicle for the delivery of photosensitizers (PS) from systems of release (DDS) for photodynamic therapy applications Methods: In this work was to synthesized hydroxyapatite microspheres (meHAp), encapsulated with chloroaluminium phthalocyanine (ClAlPc), for DDS. meHAp was synthesized using vaterite as a template. The drug was encapsulated by mixing meHAp and a 50.0 mg.mL− 1 ClAlPc solution. Photochemical, photophysical, and photobiological studies characterized the system. Results: The images from the SEM analysis showed the spherical form of the particles. All spectroscopic results showed excellent photophysical parameters of the drug studied when served in the meHAp system. The incorporation efficiency was 57.8 %. The trypan blue exclusion test results showed a significant reduction (p < 0.05) in cell viability for the groups treated with PDT at all concentrations above 250 μg.mL− 1 . In 9 L/lacZ gliosarcoma cells, PDT mediated at concentrations from 250 to 62.5 µg.mL− 1 reduced cell viability by more than 98 %. In the cell internalization study, it was possible to observe the internalization of phthalocyanines at 37 ◦C, with the accumulation of PS in the cytoplasm and inside the nucleus in the two tested concentrations. Conclusions: From all the results presented throughout the article, the meHAp system shows promise for use as a modified release system (DSD) in photodynamic therapy.
Application of mid-infrared vibrational spectroscopy with Fourier transform (FTIR) in quality evaluation in commercial coffees
(CDRR Editors) Fontes, Vitória; Pereira, Douglas Cubas; Lyra, Lucas Ferreira; Sakane, Kumiko Koibuchi
Currently, Brazil is the largest exporter and producer of coffee in the world, and it is the second most consumed beverage in the world, only behind water. In the years 2019 and 2020 it is estimated that the world consumption of coffee was 168.84 million bags of 60 kg, Brazil consumed 20 million bags of coffee, the second-largest consumer in the world, only behind the United States with 25 million bags. The techniques such as infrared spectroscopy has been applied in the food industry, as it is a fast, easy technique, without the need for reagents, free from polluting processes, and capable of analyzing the simultaneous composition of the constituents. The present study aims to analyze the changes in the chemical constituents of Brazilian commercial coffees as a function of shelf life through Fourier transformed infrared spectroscopy (FT-IR) associated with chemometric methods. The experiments were carried out within the expiration date, 6 months, and a year after the expiration date. Spectra were obtained in the range from 4000 to 500 cm-1. The studies of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were made as discrimination methods. The areas in the region from 2970 to 2830 cm-1 and 1765 to 1720 cm-1 were calculated to analyze the alteration as a function over time. The results suggest that these bands in coffee are sensitive over time and to the storage conditions, promoting changes in aroma and flavor.
Gelatin nanoparticles via template polymerization for drug delivery system to photoprocess application in cells
(Taylor & Francis) Trindade, Agnes Cecheto; Castro, Pedro Augusto Rodrigues Ribeiro de; Pinto, Bruna Cristina dos Santos; Ambrósio, Jéssica Aparecida Ribeiro; Oliveira Junior, Benedito Marcio de; Beltrame Junior, Milton; Gonçalves, Erika Peterson; Pinto, Juliana Guerra; Ferreira-Strixino, Juliana; Simioni, Andreza Ribeiro
Photodynamic therapy (PDT) is a clinical treatment based on the activation of light-absorbing photosensitizers (PS) to generate reactive oxygen species, which are toxic to the targeted disease cells. Because most PS are hydrophobic with poor water solubility, it is necessary to encapsulate and solubilize PS in aqueous condi- tions to improve the photodynamic action for this compound. In this work, gelatin-poly(acrylic acid) nanoparticles (PAA/gelatin nanoparticles) via template polymerization for incorporation alu- minum chloride phthalocyanine (ClAlPc) as a model drug for PDT application were developed. Biocompatible core-shell polymeric nanoparticles were fabricated via template polymerization using gelatin and acrylic acid as a reaction system. The nanoparticulate system was studied by scanning electron microscopy, steady- state, and their biological activity was evaluated using in vitro cancer cell lines by classical MTT assay. The obtained nanopar- ticles had a spherical shape and DLS particle size were deter- mined further and was found to be around 170nm. The phthalocyanine-loaded-nanoparticles maintained their photophysi- cal behaviour after encapsulation. It is found that ClAlPc can be released from the nanoparticles in a sustained manner with a small initial burst release. In vitro cytotoxicity revealed that ClAlPc- loaded nanoparticles had similar cytotoxicity to free ClAlPc with mouse melanoma cancer cell line (B16-F10). In vitro photoeffects assay indicated that the nanoparticle formulation was superior in anticancer effect to free ClAlPc on mouse melanoma cancer cell line B16-F10. The results indicate that ClAlPc encapsulated in gel- atin-poly(acrylic acid) nanoparticles are a successful delivery sys- tem for improving photodynamic activity in the target tissue.
Anatase film on orotracheal tubes to mitigate Staphylococcus aureus
(American Scientific Publishers) Manfroi, Lucas Augusto; Silva, Michely Glenda Pereira da; Vieira, Angela Aparecida; Macário, Paulo Fabrício; Silva, Newton Soares da; Marques, Francisco Chagas; Vieira, Lucia
Bacterial contamination in hospital environments is a significant concern for patient admissions. Aiming to reduce contamination, titanium dioxide film (TiO2) in the anatase phase has been prepared on the surface of polyvinyl chloride (PVC) tubes. The PVC tube material was used to study the film’s effectiveness in inhibit- ing bacterial growth and cell viability. The morphology and composition of deposited films were investigated using a Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) map. In addition, Fourier-Transform Infrared Spectroscopy (FTIR) and XRD diffractogram were used to analyze film composition and phase, respectively. The adhesion of TiO2 film on PVC substrate was determined using ScotchTM tape-test according to ASTM: D3359-09, 2010, and the film surface morphology was analyzed by the MEV-FEG tech- nique and EDS map. The bacterial viability was performed with Staphylococcus aureus, and cell viability was performed using L929 strain mouse fibroblasts. The results of TiO2 in the anatase phase deposited by ALD on the PVC surface demonstrate good adherence and the film’s effectiveness in inhibiting bacterial growth and cell viability.
SiOx Top Layer on DLC Films for Atomic Oxygen and Ozone Corrosion Protection in Aerospace Applications
(Universidade Federal de São Carlos) Ferreira, Leandro Lameirão; Radi, Polyana Alves; Silva Sobrinho, Argemiro Soares da; Vieira, Lucia; Leite, Douglas Marcel Gonçalves; Recco, Abel Andre Candido; Reis, Danieli Aparecida Pereira; Massi, Marcos
Every year, billions of dollars are invested in research and development for space applications, including new systems, new technologies, and new materials. DLC (Diamond-Like Carbon) is a promising material for use in these applications, but its use faces a technological barrier, since it is severely etched by atomic oxygen and ozone. In this study, SiOx-DLC thin films were deposited as a top layer of diamond-like carbon (DLC) films on Ti-6Al-4V substrates to increase resistance against corrosion by atomic oxygen and ozone as well as meet the requirements for use in Low Earth Orbit (LEO) satellites. The corrosion resistance of the films was evaluated using oxygen plasma, and the tribological and mechanical properties were investigated. The SiOx-DLC top layer reduced the corrosion rate two orders of magnitude and increased the critical load from 16.2 ± 1.5 N to 18.4 ± 0.4 N.
Replacement of the carbon catabolite regulator (cre1) and fed-batch cultivation as strategies to enhance cellulase production in Trichoderma harzianum
(Elsevier) Delabona, Priscila da Silva; Lima, Deise Juliana; Codima, Carla Aloia; Ramoni, Jonas; Gelain, Lucas; Melo, Vandierly Sampaio de; Farinas, Cristiane Sanchez; Pradella, José Geraldo da Cruz; Seiboth, Bernhard
This work focused on mitigating carbon catabolic repression (CCR) and increasing cellulase production in Trichoderma harzianum based on the cre1 deletion. The CRE1 protein (encoded by cre1) has been described as a cellulase transcriptional repressor in various cellulotic fungi, but has not been investigated in T. harzianum. We constructed ∆cre1 T. harzianum by replacing the cre1 gene with the amdS gene from Aspergillus nidulans. Quantitative PCR analysis of some Cazymes genes showed that CRE1 acts positively on gh61, bgl1 and xyn2. The fed-batch strategy using hydrothermal sugarcane bagasse by the ∆cre1_Th15 produced a constant rate of FPase under glucose influence, suggesting that the knockout of the carbon catabolite regulator improved the glycoside hydrolases (FPase 1.96 ± 0.32 IU/mL; β-glucosidase 5.67 ± 0.28 IU/mL and xylanase 327. 26 ± 14.25 IU/mL), so that this strain can be used for biorefinery purposes.
High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates
(MDPI) Ferreira, Eder Henrique Coelho; Vieira, Angela Aparecida; Vieira, Lucia; Fechine, Guilhermino José Macêdo
Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE- UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a signifi- cant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomogra- phy, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction co- efficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.
Enamel erosion prevention and mechanism: effect of 10.6-μm wavelength CO2 laser low power density irradiation studied by X-ray fluorescence and infrared spectroscopy and scanning electron microscopy
(Springer Nature Link) Lopes, Francialza Veras Viana; Sanches, Roberto Pizarro; Vasconcelos, Getúlio de; Bhattacharjee, Tanmoy T.; Santo, Ana Maria do Espírito; Soares, Luís Eduardo Silva
Purpose This study assessed the effects of carbon dioxide (CO2) laser (λ = 10.6 μm, 5 W, 70 J/cm2) irradiation alone and after treatment with neutral fluoride gel on enamel and their efficacy in preventing enamel erosion compared to untreated and fluoride gel-treated enamel. Methods Enamel surfaces of the bovine incisor (n = 7/group) were treated with artificial saliva (S, negative control), neutral fluoride (NF, positive control), CO2 laser irradiation (L), and NF + laser (NF + L). Samples were acid demineralized (soft drink, pH ~ 3.2, 10 min), remineralized (saliva, 37 °C, 1 h), and analyzed using micro-energy-dispersive X-ray fluorescence spectrom- etry (μ-EDXRF), attenuated total reflectance–Fourier-transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). Results Results suggest that NF gives the best protection against erosion, followed by NF + L and L. μ- EDXRF showed that changes due to laser treatment in L and NF + L were uneven. SEM images showed morphological changes in L and NF + L such as craters, fissures, and roughness in some regions, again indicating the unevenness of laser-induced enamel changes. ATR-FTIR mean spectra intensity levels and principal component analysis also indicate higher efficacy of fluoride over laser treatments and unevenness of laser treatments. Conclusion Overall, it can be concluded that CO2 laser parameters need to be further investigated to promote adequate protection with minimum surface changes.
Continuous production of enzymes under carbon-limited conditions by Trichoderma harzianum P49P11
(Elsevier) Gelain, Lucas; Kingma, Esther; Pradella, José Geraldo da Cruz; Costa, Aline Carvalho da; Wielen, Luuk Van Der; Gulik, Walter Martin van
Carbon-limited chemostat cultures were performed using different carbon sources (glucose, 10 and 20 g/L; sucrose, 10 g/L; fructose/glucose, 5.26/5.26 g/L; carboxymethyl cellulose, 10 g/L; and carboxymethyl cellulose/glucose, 5/5 g/L) to verify the capability of the wild type strain Trichoderma harzianum to produce extracellular enzymes. All chemostat cultures were carried out at a fixed dilution rate of 0.05 h . Experiments using glucose, fructose/glucose and sucrose were performed in duplicate. Glucose condition was found to induce the production of enzymes that can catalyse the hydrolysis of p-nitro- phenyl-b-D-glucopyranoside (PNPGase). A concentration of 20 g/L of glucose in the feed provided the highest productivity (1048 ± 16 U/mol h). Extracellular polysaccharides were considered the source of inducers. Based on the obtained results, a new PNPGase production process was developed using mainly glucose. This process raises interesting possibilities of synthesizing the inducer substrate and the induced enzymes in a single step using an easily assimilated carbon source under carbon-limited conditions.
Apatite‐like forming ability, porosity, and bond strength of calcium aluminate cement with chitosan, zirconium oxide, and hydroxyapatite additives
(Wiley) Saltareli, Fernanda Mara; Leoni, Graziela Bianchi; Aguiar, Nayara de Lima Ferraz; Faria, Natália Spadini de; Oliveira, Ivone Regina de; Bachmann, Luciano; Raucci Neto, Walter
This study evaluated the effect of chitosan, zirconium oxide, and hydroxyapatite on the apatite-like forming ability, porosity, and bond-strength of calcium-aluminate cements (C). Three hundred bovine root-slices were assigned to one of five groups, according to the material: MTA, C, C + chitosan (Cchi), C + zirconium oxide (Czio),and C + hydroxyapatite (Chap), and within each group, two subgroups, according to the immersion: deionized water or phosphate-buffered saline (PBS) up to 14 days.Assessments (n = 10) of apatite-like forming ability were performed using scanning-electron microscopy, energy-dispersive x-ray spectroscopy, Fourier-transform infra-red spectroscopy, and x-ray diffraction. PBS was evaluated for pH and Ca 2+ release(n = 10). Bond-strength was analyzed by push-out test (n = 10) and porosity bymicro-CT (n = 10). Chemical and push-out data were analyzed by ANOVA and Tukey's tests (α = .05). Porosity data were analyzed by the Kruskal-Wallis and SNK tests (α = .05). Similar Ca/P ratios were observed between all groups (p > .05). The pH of MTA and Cchi were higher than that of other cements at d 3 and 6 (p < .05).Cchi had a higher release of Ca 2+ up to 6 days (p < .05). All cements had lower poros-ity after PBS (p < .05). Cchi and Chap had similar porosity reduction (p > .05), and were higher than MTA, C, and Czio (p < .05). Cchi had higher bond-strength than the other groups (p < .05). PBS samples had higher bond-strength (p < .05). All cements had hydroxyapatite deposition and the chitosan blend had the lowest porosity and the highest bond-strength

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