Mono- versus Multi-phosphonic Acid Based PEGylated Polymers for Functionalization and Stabilization of Metal (Ce, Fe, Ti, Al) Oxide Nanoparticles in Biological Media

International audienceFor applications in nanomedicine, particles need to be functionalized to prevent protein corona formation and/or aggregation. Most advanced strategies take advantage of functional polymers and assembly techniques. Nowadays there is an urgent need for coatings that are tailored according to a broad range of surfaces and that can be produced on a large scale. Herein, we synthesize mono-and multi-phosphonic acid based poly(ethylene glycol) (PEG) polymers with the objective of producing efficient coats for metal oxide nanoparticles. Cerium, iron, titanium and aluminum oxide nanoparticles of different morphologies (spheres, platelets, nanoclusters) and sizes ranging from 7 to 40 nm are studied in physiological and in protein rich cell culture media. It is found that the particles coated with mono-functionalized polymers exhibit a mitigated stability over time ( months). With the latter, PEG densities in the range 0.2-0.5 nm-2 and layer thickness about 10 nm provide excellent performances. The study suggests that the proposed coating allows controlling nanomaterial interfa-cial properties in biological environments

Polymer coated cerium oxide nanoparticles as oxidoreductase-like catalysts

Cerium oxide nanoparticles have been shown to mimic oxidoreductase enzymes by catalyzing the decomposition of organic substrates and reactive oxygen species. This mimicry can be found in superoxide radicals and hydrogen peroxides, harmful molecules produced in oxidative stress asso-ciated diseases. Despite the fact that nanoparticle functionalization is mandatory in the context of nanomedicine, the influence of polymer coatings on their enzyme-like catalytic activity is poorly understood. In this work, six polymer coated cerium oxide nanoparticles are prepared by associa-tion of 7.8 nm cerium oxide cores with two poly(sodium acrylate) and four poly(ethylene glycol) (PEG) grafted copolymers with different terminal or anchoring end groups, such as phosphonic acids. The superoxide dismutase-, catalase-, peroxidase- and oxidase-like catalytic activities of the coated nanoparticles were systematically studied. It is shown that the polymer coatings do not af-fect the superoxide dismutase-like, impair the catalase-like and oxidase-like and surprisingly im-proves peroxidase-like catalytic activities of cerium oxide nanoparticles. It is also demonstrated that the particles coated with the PEG-grafted copolymers perform better than the poly(acrylic acid) coated ones as oxidoreductase-like enzymes, a result that confirms the benefit of having phosphon-ic acids as anchoring groups at the particle surface.Comment: 23 pages, 8 figures, 3 table

Spouted bed dried Rosmarinus officinalis extract: a novel approach for physicochemical properties and antioxidant activity

In this study, a conical-cylindrical spouted bed dryer with Teflon® beads as spouting material was used for producing powdered rosemary (Rosmarinus officinalis L.) extract. The influence of the inlet drying gas temperature (Tgi) and the percentage ratio between the feed rate of concentrated liquid extract by the maximum evaporation capacity of the spouted bed (Ws/Wmax) on selected physicochemical properties of the finished products were investigated. Antioxidant properties of the concentrated liquid extract and dried extracts were also evaluated by the 2.2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) and lipid peroxidation induced by Fe2+/citrate (LPO) methods; and compared with the values obtained for a lyophilized extract (used as a control). Colloidal silicon dioxide (Tixosil® 333) and maltodextrin (DE 14) at a 2:1 ratio was added to the concentrated extract before drying (4.4% w/w) to improve the drying performance. The drying variables Ws/Wmax and Tgi have statistically significant influence on total polyphenols and total flavonoid contents of the dried powders. The concentrated extract (on dry basisbeing absolute solid content) showed superior antioxidant activity (AA) compared to both the spouted bed dried and the lyophilized extracts; exhibiting IC50 values of 0.96 ± 0.02, 2.16 ± 0.04 and 3.79 ± 0.05 µg mL1 (DPPH method) and 0.22 ± 0.01, 1.31± 0.01 and 2.54 ± 0.02 µg mL1 (LPO method), respectively. These results of AA are comparable to values obtained for quercetin, a flavonoid compound often used as a reference standard due to its potent antioxidant activity; with IC50 of 1.17 µg mL1 (DPPH) and 0.22 µg mL1 (LPO). However, the dried rosemary extracts are about 13.5 times more concentrated than the initial concentrated extract (dry weight), with a concentration of total flavonoids and polyphenols compounds ranging from 4.3 to 12.3 and from 1.2 to 4.7 times higher than the concentrated extract values (wet basis). The AA per dry product mass was thus significantly higher than the values measured for concentrated extractive solution, irrespective of some losses of AA apparently due to the drying process.Foundation of Research Support of the São Paulo State (FAPESP) for the funded projects 2011/10333-1, 2012/03427-2 and 2018/26069-0 and for the National Council for Scientific and Technological Development (CNPq) for the financial support. E.B.S. acknowledges the Portuguese Science and Technology Foundation (FCT) for the funded projects M-ERA-NET/0004/2015 (PAIRED) and UIDB/04469/2020 (strategic fund)info:eu-repo/semantics/publishedVersio

Streptococcus pneumoniae resistente à penicilina (PRP): uma revisão

O Streptococcus pneumoniae é um dos agentes etiológicos mais comuns na prática clínica. Nos últimos anos, a bactéria tem ganhado notoriedade no que diz respeito à resistência a fármacos antimicrobianos. No que diz respeito ao pneumococo resistente à penicilina (PRP), ainda são necessários maiores esclarecimentos acerca dos exatos mecanismos moleculares que constituem todo o processo de resistência.  Nesse sentido, o presente estudo visa revisar os princípios microbiológicos básicos do PRP, bem como elucidar as implicações desse agente na prática clínica, através de uma pesquisa descritiva, qualitativa e retrospectiva. Além de causar diversas doenças (principalmente respiratórias), o S. pneumoniae possui diversos fatores de virulência relacionados à sua variação genômica, que contribuem para sua capacidade de infectar o hospedeiro. Já a resistência do pneumococo à penicilina, ocorre principalmente devido a alterações nas proteínas de ligação à penicilina (PLPs), mais especificamente, PLP1a, 2x e 2b, comprometendo a eficácia do tratamento. A resistência pode se disseminar entre cepas por elementos genéticos móveis, tornando difícil o controle da infecção. A OMS destaca a importância de novas abordagens terapêuticas para lidar com o S. pneumoniae resistente a medicamentos. Essas cepas têm implicações clínicas graves, que incluem falha no tratamento, além de morbidade e mortalidade elevadas. Desta forma, conclui-se que a resistência em S. pneumoniae é um desafio crescente na prática médica, que requer vigilância epidemiológica, estratégias de prevenção e desenvolvimento de novos antibióticos

Polycaprolactone blended with polynitrosated polyester for local nitric oxide delivery

Orientador: Marcelo Ganzarolli de OliveiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: O principal objetivo deste trabalho foi desenvolver um biomaterial polimérico liberador de NO e degradável em condições fisiológicas. Para isso, filmes sólidos de blendas entre policaprolactona (PCL) e um poliéster polissulfidrilado (PSPE), sintetizado a partir da reação de policondensação entre o ácido mercaptosuccínico e o tioglicerol, foram preparadas. A influência do conteúdo de PSPE nas cinéticas de cristalização e na morfologia dos esferulitos de PCL nas blendas PCL/PSPE foi investigada por microscopia óptica de polarização de acordo com o modelo de Avrami-Ahrrenius. Demonstrou-se que o PSPE não afeta os parâmetros de cela unitária da PCL e deve se situar nas regiões amorfas interfibrilares da PCL. Os filmes de PCL/PSPE foram caracterizados por DSC, utilizando-se a equação de Fox para prever o comportamento das Tgs e o modelo de Hoffman-Weeks para determinar a temperatura de fusão de equilíbrio em função da composição da blenda. Um ensaio acelerado de degradação foi utilizado para determinar os perfis de perda de massa de filmes de PCL/PSPE devido à degradação hidrolítica. Análises por EDS e DSC, mostraram que o PSPE se degrada mais rapidamente que a PCL. Os grupos sulfidrila dos filmes de PCL/PSPE foram quantificados pelo método colorimétrico de Ellman. A superfície dos filmes de PCL/PSPE foi S-nitrosada por imersão em ácido nitroso. Os perfis de liberação de NO dos filmes de PCL/PNPE foram determinados por quimiluminescência e amperometria. Medidas de fluxo sanguíneo dérmico por fluxometria de laser Doppler, demonstraram que a aplicação tópica dos filmes de PCL/PNPE promove vasodilatação dose-dependente. O conjunto de resultados demonstra que os filmes de PCL/PNPE possuem potencial de uso como biomateriais degradáveis doadores de NO em aplicações biomédicasAbstract: The main aim of this work was the development of a nitric oxide releasing polymeric biomaterial which is degradable in phisiologycal medium. With this aim, solid films of blends of polycaprolactone (PCL) with a polysulfhydrilated polyester (PSPE), synthesized through the polycondesation reaction between mercaptosuccinic acid and thioglycerol, were prepared. The influence of the content of PSPE on the crystallization kinetics and spherulite morphology of PCL on the PCL/PSPE blends was investigated by polarizing optical microscopy, according to the Avrami-Ahrrenius model. It was shown that the PSPE does not affect the PCL¿s unitary cell parameters and must be located in the amorphous interfibrilar regions of PCL. The PCL/PSPE films were characterized by DSC using Fox equation to predict the behavior of the Tgs and the Hoffman-Weeks model to determine the equilibrium melting temperature as a function of the blend composition. An accelerated degradation essay was used to assess the mass loss profiles of PCL/PSPE films due to hydrolytic degradation. EDS and DSC analysis showed that the PSPE degrades faster than the PCL. The sulfhydryl groups of the PCL/PSPE films were quantified by the Ellman¿s colorimetric essay. The surface of the PCL/PSPE was S-nitrosated through the immersion in nitrous acid. The NO release profiles of the PCL/PNPE films were determined by chemiluminescense and amperometry. The films were shown to promote topical skin vasodilation in a dose dependent manner. Measurements of dermal blood flow by laser Doppler flowmetry showed that the topical application of the PCL/PNPE films promotes a dose-dependent vasodilation. Altogether, these results show that the PCL/PNPE films have potential to be used as nitric oxide-releasing biomaterials in biomedical applicationsDoutoradoFísico-QuímicaDoutor em CiênciasCAPE

PLGA polymeric nanoparticles in the treatment of hepatocellular carcinoma and colorectal cancer

Orientador: Francisco Benedito Teixeira PessineDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: Neste trabalho preparamos e utilizamos nanopartículas de PLGA-DOTAP encapsulando o peptídeo P17, que bloqueia a ação da citocina imunossupressora TGF-b, no tratamento de camundongos BALB/c fêmea, inoculados via subcutânea com células de hepatocarcinoma (CHC) murino BNL ou de câncer colo-retal (CCR) murino CT26. No modelo de CHC, nanopartículas foram administradas em conjunto com vírus adenoassociados recombinantes, cujo DNA viral codificava a citocina imunoestimuladora IL-12. No modelo de CCR, nanopartículas foram testadas como potencializadoras de uma vacina contra câncer colo-retal. Além disso, a biodistribuição de nanopartículas de PLGA-DOTAP, funcionalizadas ou não com a glicoproteína assialofetuína, foi verificada pelos métodos de bioluminescência em câmara escura com detector CCD e por PCR quantitativa em tempo real. Como resultado, observou-se que nanopartículas de PLGA-DOTAP encapsulando o fármaco P17 são capazes de potencializar a vacina contra CCR e que a glicoproteína assialofetuína é capaz de direcioná-las ao fígadoAbstract: In this research we prepared and used PLGA-DOTAP nanoparticles loaded with the peptide P17, which blocks the action of the imunossupressive cytokine TGF-b, in the treatment of female BALB/c mice inoculated subcutaneously with BNL (murine hepatocellular carcinoma (HCC) cells) or CT26 (murine colorectal cancer (CRC) cells). In the HCC model, nanoparticles were administered together with recombinant adeno-associated virus whose viral DNA encodes the immunostimulatory cytokine IL-12. In the CRC model, nanoparticles were tested as vaccine booster against colorectal cancer. In addition, the biodistribution of PLGA-DOTAP nanoparticles functionalized or not with the asialofetuin glycoprotein was verified by bioluminescence and real-time quantitative PCR. As a result, it was observed that P17 containing DOTAP-PLGA nanoparticles are able to increase vaccine efficiency and that asialofetuin glycoprotein is able to direct them to the liverMestradoFísico-QuímicaMestre em Químic

Poly-ε-caprolactone/polysulfhydrylated polyester blend: a platform for topical and degradable nitric oxide-releasing materials

Polymeric biomaterials for implantable medical devices are subject to demands that go beyond passive biocompatibility. Inhibition of thrombus formation, reduced inflammatory response and the eventual complete bioabsorption of the implant are central challenges for emerging polymeric biomaterials. Nitric oxide (NO) released at the biomaterial/tissue interface may inhibit platelet adhesion and improve tissue integration in blood-contacting/implanted devices. In addition, local NO release may increase vasodilation, thereby improving ischemic conditions in topical applications. In this study, we present a novel degradable NO-releasing polymeric platform based on blended poly-ε-caprolactone (PCL)/polysulfhydrylated polyester (PSPE). PCL formed miscible blends with PSPE up to 45 wt% of PSPE. S-nitrosation of the PCL/PSPE blends converted the surface PSPE component into a NO-releasing polynitrosated polyester (PNPE). Real-time chemiluminescence NO detection showed that blends with different PCL:PSPE ratios allow surface S-nitrosothiol concentrations in the range of 0.5–1.5 μmol/cm2.Topical application of blended PCL/PNPE films on the healthy skin led to a 6–10-fold increase in the skin blood flow due to local NO delivery, as shown by in vivo laser-Doppler flowmetry. Blended PCL/PSPE films displayed higher hydrophilicity and a 2–11-fold increase in the hydrolytic mass loss, compared to pure PCL films. Therefore, PCL/PSPE blend is a potential biomaterial platform for local NO delivery and more quickly degradable biomedical devices.109143152CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorFAPESP – Fundação de Amparo à Pesquisa Do Estado De São PauloSem informação2016/02414-

Amperometric Quantification Of S-nitrosoglutathione Using Gold Nanoparticles: A Step Toward Determination Of S-nitrosothiols In Plasma

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)S-Nitrosothiols (RSNOs) are carriers of nitric oxide (NO) and have important biological activities. We propose here the use of gold nanoparticles (AuNPs) and NO-selective amperometric microsensor for the detection and quantification Of S-nitro-soglutathione (GSNO) as a step toward the determination of plasma RSNOs. AuNPs were used to decompose RSNOs with the quantitative release of free NO which was selectively detected, with a NO microsensor. The optimal [GSNO]/[AuNPs] ratio was determined, corresponding to an excess of AuNP surface relative to the molar GSNO amount. Moreover, the influence of free plasma thiols on this method was investigated and a protocol based on the blocking of free thiols, with iodoacetic acid, forming the carboxymethyl derivative of the cysteine residues, is proposed.88631153120Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)"French Committee for Evaluation of Academic and Scientific Cooperation with Brazil (COFECUB)" [802-14]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Nanoparticle-lipid interaction: job scattering plots to differentiate vesicle aggregation from supported lipid bilayer formation

The impact of nanomaterials on lung fluids, or on the plasma membrane of living cells, has prompted researchers to examine the interactions between nanoparticles and lipid vesicles. Recent studies have shown that nanoparticle-lipid interaction leads to a broad range of structures including supported lipid bilayers (SLB), particles adsorbed at the surface or internalized inside vesicles, and mixed aggregates. Currently, there is a need to have simple protocols that can readily evaluate the structures made from particles and vesicles. Here we apply the method of continuous variation for measuring Job scattering plots and provide analytical expressions for the scattering intensity in various scenarios. The result that emerges from the comparison between experiments and modeling is that electrostatics play a key role in the association, but it is not sufficient to induce the formation of supported lipid bilayers.Science and Engineering for Advanced Materials and devicesUniversité Sorbonne Paris CitéAssemblage Macromoléculaire Hors-équilibre Compréhension, Contrôle & nouvelles structuresInteractions des nanoparticules avec des surfaces mimétiques des poumons et du liquide pulmonaireNanoparticules d'oxyde de cérium recouvertes de polymères industriels innovants pour le traitement des accidents vasculaires cérébrau

A new mechanism for the electrostatic charge build-up and dissipation in dielectrics

Excess electrostatic charge induction on paper under an electrostatic potential, at different relative humidity (RH) values, was measured using a Kelvin electrostatic voltmeter set-up. Results show that samples under a positive potential accumulate excess negative charges, which are dissipated when the potential is brought down to zero. Rates of charge accumulation and dissipation over the samples are equal under constant RH and both rates decrease markedly at lower RH values. These results are interpreted using a new model for the electrification of insulators, based on the effect of the electric potential on the electrochemical potential (µi=µi° + RTln a + zFV) of H(H2O)n+ and OH(H2O)n- ions within water adsorbed on insulators. Rates of paper electrification and re-neutralization are thus strongly dependent on the amount of water in the atmosphere. This model explains the experimental results presented in this work and also a number of hitherto unexplained reports on electrostatic phenomena