Síntese de nanopartículas de prata suportadas em microesferas e filmes de quitosana: estudo da atividade antibacteriana e aplicação na liberação controlada de ibuprofeno

Since the 1990s studies related to chitin and chitosan polymers have been stimulated. The presence of more NH2 groups in chitosan allows its application as an efficient biomaterial without drug loading and adsorption of metallic cations. In this work, chitosan films and microspheres were made for use in silver ion adsorption procedures, drug release and antibacterial activity. The polymer showed a degree of deacetylation corresponding to 81% and zero loading point at pH ~ 7. As obtained microspheres had a mean diameter of 2911 mm and a standard deviation of 0.325, when used. The use of chitosan in the form of microspheres and films provides an increase of the surface area, besides facilitating the handling of the polymer. The films were formed with single step silver nanoparticles. The best pH for the Ag+ ion adsorption study in the aqueous medium is in the pH range of 5 to 7, the best fit for the Langmuir model, the optimal time for the maximum adsorption of 10 hours and the apparent energy value of adsorption (E) of 6,9 kJ / mol, which characterizes it physical adsorption. The study of ibuprofen release was performed in simulated gastric fluid and simulated intestinal fluid, further release of the drug occurs no neutral pH of intestinal fluids. Transdermal delivery of drug by films was performed at pH = 7.4 to simulate blood tissue and the apex of ibuprofen release occurred early in contact with the simulated fluid material. As microspheres and films with silver nanoparticles they demonstrate activity against E. coli and S. aureus.Desde a década de 90 que estudos relacionados com os polímeros quitina e quitosana têm sido estimulados. A presença em maior quantidade de grupos NH2 na quitosana permite sua aplicação como biomaterial eficiente no carreamento de fármacos e na adsorção de cátions metálicos. Neste trabalho foram preparados filmes e microesferas de quitosana para uso em procedimentos de adsorção de íons prata, liberação de fármaco e atividade antibacteriana. O polímero apresentou grau de desacetilação correspondente a 81% e ponto de carga zero em pH~7. As microesferas obtidas apresentaram um diâmetro médio de 2,911 mm e um desvio padrão de 0,325, quando úmidas. O uso da quitosana na forma de microesferas e filmes proporciona um aumento da área superficial, além de facilitar o manuseio do polímero. Os filmes obtidos foram formados com nanopartículas de prata em etapa única. O melhor pH para o estudo de adsorção de íons Ag+ em meio aquoso está na faixa de pH de 5 a 7, o melhor ajuste foi ao modelo de Langmuir, o tempo ótimo para ocorrer adsorção máxima foi de 10 horas e o valor de energia aparente de adsorção (E) de 6,9 kJ/mol, o que a caracteriza adsorção física. O estudo de liberação de ibuprofeno foi realizado em fluido gástrico simulado e fluido intestinal simulado, a maior liberação do fármaco ocorreu no pH neutro dos fluidos intestinais. A liberação transdérmica de fármaco pelos filmes foi realizada apenas em pH=7,4 para simular o tecido sanguíneo e o ápice da liberação de ibuprofeno ocorreu logo no início do contato do material com o fluido simulado. As microesferas e os filmes com nanopartículas de prata demonstram ter atividade contra E. coli e S. aureus

Plant and Bacterial Cellulose: Production, Chemical Structure, Derivatives and Applications

Cellulose is one of the most abundant biopolymers in nature. It is used in the industry in various ways, in both its original and modified forms and the latter are called cellulose derivatives. These derivatives are used in several industrial such as the pharmaceutical, food, cosmetics and can be used in solid or semi-solid form. An important application that has been currently clarified is the use of some types of cellulose derivatives as adsorbents for both metal ions and other molecules. An example is the decontamination of wastewater, as with the industrial development, some water sources are compromised and decontamination by conventional means is often not enough, hence the need for new techniques. The main advantage of using natural polymers is that they are biodegradable, because it is extremely important that a product disappear after fulfilling its purpose. An example of a natural polymer is cellulose synthesized by bacteria, also known as bacterial cellulose (BC). It has been the subject of several studies in the last decade, mainly due to the fact that it is a highly pure polymer, which makes their physical and chemical properties very different from those of plant cellulose, and also because it is easy to produce, with yields varying from one bacterium to another. The aim of this paper was to gather general information about the structures, production mode, synthesis and industrial applications of bacterial, vegetable and cellulose derivatives. DOI: http://dx.doi.org/10.17807/orbital.v11i5.134

Plant and Bacterial Cellulose: Production, Chemical Structure, Derivatives and Applications

Cellulose is one of the most abundant biopolymers in nature. It is used in the industry in various ways, in both its original and modified forms and the latter are called cellulose derivatives. These derivatives are used in several industrial such as the pharmaceutical, food, cosmetics and can be used in solid or semi-solid form. An important application that has been currently clarified is the use of some types of cellulose derivatives as adsorbents for both metal ions and other molecules. An example is the decontamination of wastewater, as with the industrial development, some water sources are compromised and decontamination by conventional means is often not enough, hence the need for new techniques. The main advantage of using natural polymers is that they are biodegradable, because it is extremely important that a product disappear after fulfilling its purpose. An example of a natural polymer is cellulose synthesized by bacteria, also known as bacterial cellulose (BC). It has been the subject of several studies in the last decade, mainly due to the fact that it is a highly pure polymer, which makes their physical and chemical properties very different from those of plant cellulose, and also because it is easy to produce, with yields varying from one bacterium to another. The aim of this paper was to gather general information about the structures, production mode, synthesis and industrial applications of bacterial, vegetable and cellulose derivatives. DOI: http://dx.doi.org/10.17807/orbital.v11i5.134

ESTUDO TEÓRICO DA INTERAÇÃO DA QUITOSANA COM UMA SUPERFÍCIE DE PRATA: UM ESTUDO DF

Os materiais que combinam estruturas de prata e o biopolímero de quitosana têm sido extensivamente estudados na literatura devido suas inúmeras aplicabilidades como na de liberação de fármacos, sensores, no controle biológico e até no tratamento contra o câncer. Nesta perspectiva, o presente artigo realizou o estudo teórico em nível de teoria do funcional de densidade da interação de um monômero de quitosana neutra (DQ) e o mesmo protonado (DQP) com uma superfície de prata (S). As análises dos índices reatividade, Mapa de Potencial Eletrostático e Orbitais Moleculares de Fronteira mostraram que a interação entre os compostos podem ocorrer. As interações das espécies não protonadas com a superfície ocorreram por interação do polímero com a parte central da superfície e também entre o par de elétrons do nitrogênio com os átomos de prata. Para as espécies protonadas todas as interações convergiram para o mesmo sítio que foi sobre a superfície de prata. Comparando os sistemas protonado e não protonado, é possível inferir que as espécies protonadas interagem mais efetivamente com a superfície da prata através de efeitos eletrostáticos

EVALUATION OF THE CYTOTOXICITY AND GENOTOXICOLOGICAL SAFETY PROFILE OF BIOACTIVE SILVER(I) COMPLEXES WITH AMINOADAMANTANE LIGANDS

Silver(I) complexes of amantadine (atdH), memantine (mtnH) and rimantadine (rtdH), named Ag-atd, Ag-mtn and Ag-rtd, respectively, were recently synthesized and described in the literature as promising antibacterial agents. In the present study, the cytotoxicity of such complexes was evaluated against cultures of primary epidermal keratinocytes (HaCaT) and murine melanoma tumor cells (B16-F10), and mutagenicity was studied by the Ames test to investigate their abilities to induce gene mutations. The Ames test was performed using Salmonella Typhimurium strains (TA98, TA100, TA102 and TA97a) capable of detecting frameshift and base pair substitution gene mutations, in experiments with and without metabolic activation (microsomal fraction S9). This study revealed significant cytotoxic activity against tumor cells and selectivity of Ag-atd and Ag-rtd complexes when compared to non-tumor human keratinocyte cells. Moreover, the Ag(I) complexes did not induce a significant growth in the number of revertant colonies when comparing with the negative control, both in the experiments without and with metabolic activation, indicating absence of mutagenic activity. The results are encouraging and collaborate in the genotoxicological investigations necessary for understanding the interaction and ability of the silver complexes to induce mutations and contribute to ensure their uses as future antibacterial or antitumor agents

DFT study of bismuth subsalicylate adsorption on bow-tie dendrimer nanocarrier as drug delivery agents

Ulcerative colitis is a subtype of inflammatory bowel disease with symptoms that progress from mild to severe. It has multiple treatment options, but requires effective monotherapy for its treatment. In this context, a theoretical study was conducted on the interaction of bismuth subsalicylate (BSS) with a bow-tie (DP) polyester dendrimer for use as a nanocarrier. The reactivity indices and frontier molecular orbitals indicate that these systems can interact. The complexes were formed through the interaction of the oxygens of the dendrimer with the bismuth of the BSS and also by hydrogen bonding. The ΔG values were > 0 kcal mol−1, which indicated that the systems are not spontaneous, although the values of adsorption energies (Eads) and enthalpy showed values < 0 kcal mol−1, showing that interactions can occur. Topological analyses based on the quantum theory of atoms in molecules allowed the characterization of molecular interactions. The interactions of Bi with O were partially covalent, and the hydrogen bonds (O…H) were classified as weak or moderate. Finally, the interactions between the nanocarrier and the drug had positive results, which can be attributed to the polyester dendrimer being a good nanocarrier for the release of BSS

Synthesis, crystallographic studies, molecular modeling and in vitro biological studies of silver(I) complexes with aminoadamantane ligands

Silver(I) complexes with amantadine (atd) and memantine (mtn) were synthesized and characterized. Elemental, thermogravimetric and mass spectrometric analyses indicated a 1:2 metal/ligand ratio, with the molecular composition AgC20H34N2 center dot NO3 for Ag-atd and AgC24H42N2 center dot NO3 center dot H2O for Ag-mtn. The crystal structures of the silver(I) complexes were determined by single crystal X-ray diffractometric studies and show the coordination of amantadine and memantine to the Ag(I) ion by the nitrogen atom of the NH2 group. The spectral analysis by infrared and H-1, C-13 and {N-15, H-1} nuclear magnetic resonance (NMR) spectroscopies confirmed the coordination sites of the ligands to the silver ions. Computational studies revealed modes of vibration and bond lengths similar to those found experimentally. The in vitro antibacterial activity assays showed that amantadine is not active over the tested strains while memantine showed a low activity against Staphylococcus aureus and Pseudomonas aeruginosa. On the other hand, the complexes had a pronounced antibacterial activity over the same strains with minimum inhibitory concentration (MIC) values in the micromolar range. Biophysical assays based on fluorescence spectroscopy indicated that the silver(I) complexes interact weakly with bovine serum albumin, while agarose gel electrophoresis and competitive binding experiments revealed that the compounds interact with DNA by non-covalent interactions.173CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP407012/2018-4; 164658/20181Sem informação2013/22127-2; 2014/50906-9; 2015/20882-3; 2017/25995-6; 2018/12062-4; 2018/12590-

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p&lt;0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p&lt;0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status