38 research outputs found
Desulfurization of Dibenzothiophene by Pseudomonas fluorescens (UCP 1514) Leading to the Production of Biphenyl
Dibenzothiophene (DBT) is a typical recalcitrant thiophenic sulfur component of fuels, and its desulphurization has been a model reaction in the treatment of these compounds. Based on this information, the potential of Pseudomonas fluorescens (UCP 1514) on the desulfurization of dibenzothiphene was studied, in order to use it for reducing the sulfur content of diesel oil in compliance with environmental regulations. The result of biodegradation by the bacteria was determined by undertaking high-performance liquid chromatography of the metabolites produced. These can also be identified by gas chromatography with a mass spectrometry detector, and doing so revealed a sulfur-free product, biphenyl, as the final product of the degradation process. The results showed a decrease of 73% in dibenzothiophene content, which means that P. fluorescens removes sulfur from dibenzothiophene with a good selectivity to form biphenyl. These promising results indicate that P. fluorescens has an interesting potential to degrade sulfur-containing compounds in diesel oil and thereby could help in removing sulfur content from diesel oil. The process of microbial desulfurization described herein can be used particularly after carrying out hydrodesulfurization. Consequently, the sulfur content could be reduced even further. Applying P. fluorescens UCP 1514Â in dibenzothiophene could help to understand the nature of the biodegradation process and to achieve the regulatory standards for sulfur level in fossil fuels
Morphology of temperature-sensitive and ph-responsive ipn-hydrogels for application as biomaterial for cell growth
In the present investigation, hydrogels with pH-responsive and temperature-sensitive properties were obtained by formation of alginate-Ca network inside the PNIPAAm network resulting in an interpenetrated network system (IPN). From scanning electron microscopy (SEM) images and water uptake (WU) tests one observed that IPN hydrogels exhibited a drastic shrinking when heated above 30-35 ÂșC. The shrinking resulted in decreased average pore size, thus affect the hydrogel morphology significantly. In the pH range studied, IPN hydrogels showed significant pH dependence, which was attributed to the charged alginate groups. The results indicated that the pH-responsiveness and temperature-dependence of alginate and PNIPAAm, respectively, were preserved in IPN hydrogels. In addition, such hydrogels become less deformable when subjected to compressive stress. These hydrogels presented porous morphology that may be tuned by controlling the temperature, and this makes them attractive for applications as biomaterial in cell growth.No presente trabalho, foram sintetizados hidrogĂ©is com ambas as propriedades, termo-sensĂveis e pH-responsivos, pela formação de redes de alginato de cĂĄlcio (alginato-Ca) dentro de redes de poli(N-Isopropil Acrilamida) (PNIPAAm), resultando em um sistema IPN (sistema de redes polimĂ©ricas interpenetradas). AtravĂ©s das anĂĄlises por microscopia de varredura eletrĂŽnica (MEV) e ensaios de intumescimento foi possĂvel observar que os hidrogĂ©is IPN exibiram forte contração quando aquecidos acima da LCST (temperatura critica inferior de solubilização) da PNIPAAm, ou seja, acima de temperaturas de 30-35 ÂșC. Observou-se ainda que devido Ă contração do hidrogel, houve uma diminuição significativa nos tamanhos de poros os quais foram observados pelas micrografias. Observou-se tambĂ©m que no intervalo de pH estudado os hidrogĂ©is de IPN sofreram significativa variação da estrutura com a variação desse parĂąmetro. Tal efeito foi atribuĂdo Ă presença de grupos quĂmicos carregados com alginato, os quais possuem carga elĂ©trica negativa. Os resultados indicaram que o hidrogel formado por alginato-Ca e PNIPAAm possuĂram caracterĂsticas especificas apĂłs variação de pH e temperatura, e que tais caracterĂsticas sĂŁo derivadas dos compostos individuais envolvidos na sĂntese. Nesse caso, as propriedades de alginato-Ca e PNIPAAm livres foram preservadas dentro do hidrogel. Tal hidrogel ficou mais resistente Ă aplicação de uma tensĂŁo de compressĂŁo. Como conclusĂŁo, observou-se que os hidrogĂ©is apresentaram morfologia caracterĂstica para variaçÔes controladas de pH e temperatura, podendo ser eficientemente aplicados como biomaterial na cultura de cĂ©lulas.105110Fundação de Amparo Ă Pesquisa do Estado de SĂŁo Paulo (FAPESP)Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de NĂvel Superior (CAPES
Poly(N-isopropylacrylamide)-co-acrylamide hydrogels for the controlled release of bromelain from agroindustrial residues of Ananas comosus
This works reports the purification of bromelain extracted from Ananas comosus industrial residues by ethanol purification, its partial characterization from the crude extract as well as the ethanol purified enzyme, and its application onto poly(N-isopropylacrylamide)-co-acrylamide hydrogels. Bromelain was recovered within the 30â70â% ethanol fraction, which achieved a purification factor of 3.12-fold, and yielded more than 90â% of its initial activity. The resulting purified bromelain contained more than 360âUâ·âmgâ1, with a maximum working temperature of 60â°C and pH of 8.0. Poly(N-isopropylacrylamide)-co-acrylamide hydrogels presented a swelling rate of 125â%, which was capable of loading 56â% of bromelain from the solution, and was able to release up to 91â% of the retained bromelain. Ethanol precipitation is suitable for bromelain recovery and application onto poly(N-isopropylacrylamide)-co-acrylamide hydrogels based on its processing time and the applied ethanol prices8117191726CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGsem informaçã
Poly(n-isopropylacrylamide)-co-acrylamide Hydrogels For The Controlled Release Of Bromelain From Agroindustrial Residues Of Ananas Comosus.
This works reports the purification of bromelain extracted from Ananas comosus industrial residues by ethanol purification, its partial characterization from the crude extract as well as the ethanol purified enzyme, and its application onto poly(N-isopropylacrylamide)-co-acrylamide hydrogels. Bromelain was recovered within the 30-70â% ethanol fraction, which achieved a purification factor of 3.12-fold, and yielded more than 90â% of its initial activity. The resulting purified bromelain contained more than 360âUâ·âmg(-1), with a maximum working temperature of 60â°C and pH of 8.0. Poly(N-isopropylacrylamide)-co-acrylamide hydrogels presented a swelling rate of 125â%, which was capable of loading 56â% of bromelain from the solution, and was able to release up to 91â% of the retained bromelain. Ethanol precipitation is suitable for bromelain recovery and application onto poly(N-isopropylacrylamide)-co-acrylamide hydrogels based on its processing time and the applied ethanol prices.811719-172
Effect of polysaccharide sources on the physicochemical properties of bromelainchitosan nanoparticles
Bromelain, a set of proteolytic enzymes potential pharmaceutical applications, was encapsulated in chitosan nanoparticles to enhance enzyme stability, and the effect of different chitosan sources was evaluated. Chitosan types (i.e., low molecular weight chitosan, chitosan oligosaccharide lactate, and chitosan from shrimp shells) produced nanoparticles with different physicochemical properties, however in all cases, particle size and zeta potential decreased, and polydispersity index increased after bromelain addition. Bromelain encapsulation was higher than 84% and 79% for protein content and enzymatic activity, respectively, with low molecular weight chitosan presenting the highest encapsulation efficiency. Nanoparticle suspension was also tested for accelerated stability and rheological behavior. For the chitosanâbromelain nanoparticles, an instability index below 0.3 was recorded and, in general, the loading of bromelain in chitosan nanoparticles decreased the cohesiveness of the final suspension.This research was granted by FAPESP (2016/03444-5,2017/05275-9,and2017/05333-9), CNPq and FAEPEX, and by the Portuguese Science and Technology Foundation, Ministry of Science and Education (FCT/MEC) through national funds, and co-ïŹnanced by FEDER, under the project reference M-ERA-NET/0004/2015 (PAIRED) Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio
A Mycobacterium leprae Hsp65 Mutant as a Candidate for Mitigating Lupus Aggravation in Mice
Hsp60 is an abundant and highly conserved family of intracellular molecules. Increased levels of this family of proteins have been observed in the extracellular compartment in chronic inflammation. Administration of M. leprae Hsp65 [WT] in [NZBxNZW]F1 mice accelerates the Systemic Lupus Erythematosus [SLE] progression whereas the point mutated K409A Hsp65 protein delays the disease. Here, the biological effects of M. leprae Hsp65 Leader pep and K409A pep synthetic peptides, which cover residues 352â371, are presented. Peptides had immunomodulatory effects similar to that observed with their respective proteins on survival and the combined administration of K409A+Leader pep or K409A pep+WT showed that the mutant forms were able to inhibit the deleterious effect of WT on mortality, indicating the neutralizing potential of the mutant molecules in SLE progression. Molecular modeling showed that replacing Lysine by Alanine affects the electrostatic potential of the 352â371 region. The number of interactions observed for WT is much higher than for Hsp65 K409A and mouse Hsp60. The immunomodulatory effects of the point-mutated protein and peptide occurred regardless of the catalytic activity. These findings may be related to the lack of effect on survival when F1 mice were inoculated with Hsp60 or K409A pep. Our findings indicate the use of point-mutated Hsp65 molecules, such as the K409A protein and its corresponding peptide, that may minimize or delay the onset of SLE, representing a new approach to the treatment of autoimmune diseases