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1.
Food Chem ; 300: 125167, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31325747

RESUMO

Anthocyanin lipophilization emerged as an efficient technique to improve their chemical stability, liposolubility and antioxidant properties for novel technological applications. This work describes an efficient method for the synthesis of cyanidin-3-glucoside-fatty acid conjugate using a Candida antarctica lipase B-rich extract, without further purification and retained in a porous membrane. Due to the enzyme retention within the membrane structure it was possible to improve the yield of the lipophilization reaction by 2.5-fold as well as obtaining the product in a shorter period of time comparing with its free form. Furthermore, the membrane retention allowed for enzyme reusability, since the same conversion yield was obtained in three consecutive reaction cycles.


Assuntos
Antocianinas/metabolismo , Ácidos Graxos/metabolismo , Proteínas Fúngicas/metabolismo , Glucosídeos/metabolismo , Lipase/metabolismo , Antocianinas/química , Antioxidantes/química , Enzimas Imobilizadas/metabolismo , Glucosídeos/química
2.
ACS Appl Mater Interfaces ; 11(23): 21239-21249, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31141340

RESUMO

This work shows the ability to reversibly modulate the hydrophilicity of the hydrogels doped with iron oxide nanoparticles (MNPs) in a noninvasive way when exposed to a cyclic variation of the intensity (ON/OFF) of an external magnetic field. A reversible switching of surface contact angles was observed for magnetic PVA hydrogels when exposed to consecutive variation of the magnetic field intensity between 0 and 0.08 T. Motivated by the magnetic dependence of the hydrophilicity of these hybrid hydrogels, the impact of the magnetic field on protein sorption was also evaluated. The noninvasive regulation of protein sorption-released mechanisms was achieved by ON/OFF magnetic field switches, suggesting the possible influence of magnetic-induced hydrogel shrinking effect and changes of surface wettability on protein sorption. The capacity to magnetically modulate surface wettability and protein sorption make these magnetic hydrogels promising candidates for development of functional devices for tissue engineering, drug release applications, or biosensor systems, where the control of protein sorption and mobility are essential steps to improve the efficiency of these processes.


Assuntos
Hidrogéis/química , Campos Magnéticos , Proteínas/química , Compostos Férricos/química , Nanopartículas/química
3.
Macromol Rapid Commun ; 40(2): e1800333, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30027594

RESUMO

This article presents the synthesis of poly(methacrylic acid)-b-poly(methyl methacrylate) diblock copolymer via polymerization-induced self-assembly in the presence of iron-oxide nanoparticles. Detailed phase diagrams with and without inorganic nanoparticles were constructed. Scanning transmission electron microscopy and energy dispersive X-ray photometry studies confirme the decoration of the polymeric nanoparticles with the iron-oxide nanoparticles. These hybrid nanoparticles were used to prepare porous thin film membranes by spin coating. Finally, the magneto-responsive properties of the membranes were assessed using water filtration tests in the presence and absence of a magnetic field.


Assuntos
Técnicas de Química Sintética/métodos , Nanopartículas de Magnetita/química , Nanopartículas/química , Polímeros/química , Ácidos Polimetacrílicos/química , Polimetil Metacrilato/química , Materiais Revestidos Biocompatíveis/química , Campos Magnéticos , Nanopartículas de Magnetita/ultraestrutura , Membranas Artificiais , Microscopia Eletrônica de Transmissão e Varredura , Nanopartículas/ultraestrutura , Polimerização , Polímeros/síntese química , Porosidade
4.
J Phys Chem B ; 119(35): 11740-7, 2015 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-26252801

RESUMO

A proton nuclear magnetic relaxation dispersion (1)H NMRD study of the molecular dynamics in mixtures of magnetic ionic liquid [P66614][FeCl4] with [P66614][Cl] ionic liquid and mixtures of [P66614][FeCl4] with dimethyl sulfoxide (DMSO) is presented. The proton spin-lattice relaxation rate, R1, was measured in the frequency range of 8 kHz-300 MHz. The viscosity of the binary mixtures was measured as a function of an applied magnetic field, B, in the range of 0-2 T. In the case of DMSO/[P66614][FeCl4] the viscosity was found to be independent from the magnetic field, while in the case of the [P66614][Cl]/[P66614][FeCl4] system viscosity decreased with the increase of the magnetic field strength. The spin-lattice relaxation results were analyzed for all systems taking into account the relaxation mechanisms associated with the molecular motions with correlation times in a range between 10(-11) and 10(-7)s, usually observed by NMRD, and the paramagnetic relaxation contributions associated with the presence of the magnetic ions in the systems. In the case of the DMSO/[P66614][FeCl4] system the R1 dispersion shows the relaxation enhancement due to the presence of the magnetic ions, similar to that reported for contrast agents. For the [P66614][Cl]/[P66614][FeCl4] system, the R1 dispersion presents a much larger paramagnetic relaxation contribution, in comparison with that observed for the DMSO/[P66614][FeCl4] mixtures but different from that reported for other magnetic ionic liquid system. In the [P66614][Cl]/[P66614][FeCl4] system the relaxation enhancement associated with the paramagnetic ions is clearly not proportional to the concentration of magnetic ions, in contrast with what is observed for the DMSO/[P66614][FeCl4] system.

5.
J Biotechnol ; 189: 166-74, 2014 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-25242664

RESUMO

The impact of surface topography on the structure of proteins upon adhesion was assessed through non-invasive fluorescence monitoring. This study aimed at obtaining a better understanding about the role of protein structural status on cell-scaffold interactions. The changes induced upon adsorption of two model proteins with different geometries, trypsin (globular conformation) and fibrinogen (rod-shaped conformation) on poly-l-lactic acid (PLLA) scaffolds with different surface topographies, flat, fibrous and surfaces with aligned nanogrooves, were assessed by fluorescence spectroscopy monitoring, using tryptophan as structural probe. Hence, the maximum emission blue shift and the increase of fluorescence anisotropy observed after adsorption of globular and rod-like shaped proteins on surfaces with parallel nanogrooves were ascribed to more intense protein-surface interactions. Furthermore, the decrease of fluorescence anisotropy observed upon adsorption of proteins to scaffolds with fibrous morphology was more significant for rod-shaped proteins. This effect was associated to the ability of these proteins to adjust to curved surfaces. The additional unfolding of proteins induced upon adsorption on scaffolds with a fibrous morphology may be the reason for better cell attachment there, promoting an easier access of cell receptors to initially hidden protein regions (e.g. RGDS sequence), which are known to have a determinant role in cell attaching processes.


Assuntos
Proteínas/química , Espectrometria de Fluorescência/métodos , Tecidos Suporte/química , Materiais Biocompatíveis/química , Ácido Láctico/química , Poliésteres , Polímeros/química
6.
J Colloid Interface Sci ; 428: 16-23, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24910029

RESUMO

HYPOTHESIS: Magnetic Ionic Liquid (MILs), novel magnetic molecules that form "pure magnetic liquids," will follow the Ferrohydrodynamic Bernoulli Relationship. Based on recent literature, the modeling of this fluid system is an open issue and potentially controversial. EXPERIMENTS: We imposed uniform magnetic fields parallel to MIL/air interfaces where the capillary forces were negligible, the Quincke Problem. The size and location of the bulk fluid as well as the size and location of the fluid/air interface inside of the magnetic field were varied. MIL properties varied included the density, magnetic susceptibility, chemical structure, and magnetic element. FINDINGS: Uniform tangential magnetic fields pulled the MILs up counter to gravity. The forces per area were not a function of the volume, the surface area inside of the magnetic field, or the volume displacement. However, the presence of fluid/air interfaces was necessary for the phenomena. The Ferrohydrodynamic Bernoulli Relationship predicted the phenomena with the forces being directly related to the fluid's volumetric magnetic susceptibility and the square of the magnetic field strength. [emim][FeCl4] generated the greatest hydraulic head (64-mm or 910 Pa at 1.627 Tesla). This work could aid in experimental design, when free surfaces are involved, and in the development of MIL applications.

7.
J Phys Chem B ; 117(39): 11877-84, 2013 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-23972145

RESUMO

A study is presented of the molecular dynamics and of the viscosity in pure [Aliquat][Cl] ionic liquid and in a mixture of [Aliquat][Cl] with 1% (v/v) of [Aliquat][FeCl4]. The (1)H spin-lattice relaxation rate, R1, was measured by NMR relaxometry between 8 and 300 MHz. In addition, the translation self-diffusion, D, was measured by pulse field gradient NMR. The ILs' viscosity was measured as a function of an applied magnetic field, B, and it was found that the IL mixture's viscosity decreased with increasing B, whereas the [Aliquat][Cl] viscosity is independent of B. All experimental results were analyzed taking into account the viscosity's magnetic field dependence, assuming a modified Stokes-Einstein diffusion/viscosity relation. The main difference between the relaxation mechanisms responsible for R1 in the two IL systems is related to the additional paramagnetic relaxation contribution associated with the (1)H spins-[FeCl4] paramagnetic moments' interactions. Cross-relaxation cusps in the R1 dispersion, associated with (35)Cl and (1)H nuclear spins in the IL systems, were detected. The R1 model considered was successfully fitted to the experimental results, and it was possible to estimate the value of D at zero field in the case of the IL mixture which was consistent with the values of D measured at 7 and 14.1 T and with the magnetic field dependence estimated from the viscosity measurements. It was observed that a small concentration of [Aliquat][FeCl4] in the [Aliquat][Cl] was enough to produce a "superparamagnetic"-like effect and to change the IL mixture's molecular dynamics and viscosity and to allow for their control with an external magnetic field.

8.
J Biotechnol ; 164(3): 386-95, 2013 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-22796093

RESUMO

In the present study, the performance of a membrane bioreactor (MBR) was modelled using a hybrid approach based on the activated sludge model number 3 (ASM3) combined with projection to latent structures (PLS) to predict the residuals of the ASM. The application of ASM to MBRs requires frequent re-calibration to adjust the model to variations in influent characteristics, determined through time-consuming analysis and batch tests. Considering this problem, the objective of this study was to improve ASM prediction ability with minimal additional monitoring effort. Hybrid models were developed to predict three MBR performance parameters: mixed liquor suspended solids (MLSS), COD in the permeate (CODp) and nitrite and nitrate concentration in the permeate (NOxp). For PLS modelling of ASM residuals three input strategies were used: (1) analytic and operating data; (2) operating data plus 2D fluorescence spectroscopy; (3) all the data. The first input strategy improved ASM prediction of the three selected outputs, and highlighted the lack of detailed and real-time information from wastewater and operating parameters in the ASM used in this study. In the second input strategy, the incorporation of updated data from 2D fluorescence spectroscopy resulted on better model fitting than in the first input strategy, for all the output parameters studied. Through the hybrid modelling approach it was possible to significantly improve the ASM predictions in real-time using 2D fluorescence measurements and other relevant parameters acquired on-line, without requiring further laboratory analysis. Furthermore, the third input strategy, incorporating all the collected data, did not significantly improve the prediction of the outputs beyond the second strategy. This shows that 2D fluorescence spectroscopy is a comprehensive monitoring tool, able to capture on-line the required information to complement, through hybrid modelling, the mechanistic information described by an ASM.


Assuntos
Reatores Biológicos , Modelos Teóricos , Análise da Demanda Biológica de Oxigênio , Membranas Artificiais , Nitratos/análise , Oxigênio/análise , Esgotos , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
9.
Enzyme Microb Technol ; 51(6-7): 325-33, 2012 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-23040387

RESUMO

A combined fluorescence analysis, involving the use of steady-state fluorescence and fluorescence anisotropy was used, allowing eliciting information about the structural changes induced on trypsin after exposure to membrane surfaces with diverse chemistry, designed through a layer-by-layer methodology. Using this monitoring strategy it was possible to understand the influence of the surface chemistry on the structural characteristics of the attached proteins and how they relate to changes of their activity resulting from the adsorption process. This knowledge may be used to direct the development of surfaces with suitable chemistry, leading enzymatic-based processes with improved performance. The results obtained show clearly that trypsin exposed to different membrane surfaces, changes its conformation, either if it adsorbs to the membrane or if it remains in solution. A significant loss of enzymatic activity was observed upon the adsorption process, for the adsorbed and non-adsorbed protein. This loss of the trypsin activity was correlated with the presence of molecular unfolding events that mediate trypsin-membrane surface interactions and the decrease of the molecular mobility of the adsorbed trypsin, which was shown to be dependent on the chemical characteristics of the membrane surface. Changes on the selectivity of the adsorbed trypsin were also observed, and may be ruled by the strength of the enzyme-surface interactions established.


Assuntos
Tripsina/química , Resinas Acrílicas , Acrilonitrila/análogos & derivados , Adsorção , Biotecnologia , Enzimas Imobilizadas , Polarização de Fluorescência , Membranas Artificiais , Conformação Proteica , Espectrometria de Fluorescência , Propriedades de Superfície , Tripsina/metabolismo
10.
Water Res ; 46(11): 3623-36, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22572122

RESUMO

This work presents the development of multivariate statistically-based models for monitoring several key performance parameters of membrane bioreactors (MBR) for wastewater treatment. This non-mechanistic approach enabled the deconvolution of 2D fluorescence spectroscopy data, a powerful technique that has previously been shown to capture important information regarding MBR performance. Projection to latent structure (PLS) modelling was used to integrate 2D fluorescence data, after compression through parallel factor analysis (PARAFAC), with operation and analytical data to describe an MBR fouling indicator (transmembrane pressure, TMP), five descriptors of the effluent quality (total COD, soluble COD, concentration of nitrite and nitrate, total nitrogen and total phosphorus in the permeate) and the biomass concentration in the bioreactor (MLSS). A multilinear correlation was successfully established for TMP, CODtp and CODsp, whereas the optimised models for the remaining outputs included quadratic and interaction terms of the compressed 2D fluorescence matrices. Additionally, the coefficients of the optimised models revealed important contributions of some of the input parameters to the modelled outputs. This work demonstrates the applicability of 2D fluorescence and statistically-based models to simultaneously monitor multiple key MBR performance parameters with minimal analytical effort. This is a promising approach to facilitate the implementation of MBR technology for wastewater treatment.


Assuntos
Reatores Biológicos , Modelos Estatísticos , Eliminação de Resíduos Líquidos/instrumentação , Análise da Demanda Biológica de Oxigênio , Biomassa , Fluorescência , Membranas Artificiais , Análise Multivariada , Nitritos/análise , Fósforo/análise , Eliminação de Resíduos Líquidos/métodos
11.
Biotechnol Bioeng ; 102(4): 1098-106, 2009 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-18853411

RESUMO

The main objective of the present study was to investigate the use of in situ 2D fluorometry for monitoring key bioprocess variables in mammalian cell cultures, namely the concentration of viable cells and the concentration of recombinant proteins. All studies were conducted using a recombinant Baby Hamster Kidney (BHK) cell line expressing a fusion glycoprotein IgG1-IL2 cultured in batch and fed-batch modes. It was observed that the intensity of fluorescence signals in the excitation/emission wavelength range of amino acids, vitamins and NAD(P)H changed along culture time, although the dynamics of single fluorophors could not be correlated with the dynamics of the target state variables. Therefore, multivariate chemometric modeling was adopted as a calibration methodology. 2D fluorometry produced large volumes of redundant spectral data, which were first filtered by principal components analysis (PCA). Then, a partial least squares (PLS) regression was applied to correlate the reduced fluorescence maps with the target state variables. Two validation strategies were used to evaluate the predictive capacity of the developed PLS models. Accurate estimations of viable cells density (r(2) = 0.95; 99.2% of variance captured in the training set; r(2) = 0.91; 97.7% of variance captured in the validation set) and of glycoprotein concentration (r(2) = 0.99 and 99.7% of variance captured in the training set; r(2) = 0.99 and 99.3% of variance captured in the validation set) were obtained over a wide range of reactor operation conditions. The results presented herein confirm that 2D fluorometry constitutes a reliable methodology for on-line monitoring of viable cells and recombinant protein concentrations in mammalian cell cultures.


Assuntos
Técnicas de Cultura de Células/métodos , Fluorometria/métodos , Proteínas Recombinantes de Fusão/biossíntese , Animais , Reatores Biológicos , Linhagem Celular , Sobrevivência Celular , Cricetinae , Imunoglobulina G/biossíntese , Imunoglobulina G/genética , Interleucina-2/biossíntese , Interleucina-2/genética , Proteínas Recombinantes de Fusão/genética , Reprodutibilidade dos Testes
12.
J Photochem Photobiol B ; 82(2): 117-26, 2006 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-16288883

RESUMO

Picosecond time-resolved fluorescence, together with the addition of quenching agents, was employed to discriminate the fluorescence contributions of the two tryptophans of beta-lactoglobulin (Trp19 and Trp61) to the fluorescence decays of the protein. The fluorescence decays of beta-lactoglobulin at pH 3, 5 and 8 are best fitted using sums of three exponentials and show a dominant contribution (98%) of the components associated with the buried Trp19, which decays according to a double exponential function. The addition of acrylamide (0.05 M) causes an increase of the decay times associated with Trp19. This effect is observed at all pH values studied, but the effect is stronger at pH 3 and pH 5, than at pH 8. The unexpected increase of the decay times of Trp19 and the variation of the respective amplitudes were rationalized in terms of alterations of Trp19 mobility. The hindrance of Trp19 upon acrylamide binding was also monitored and supported by fluorescence anisotropy measurements.


Assuntos
Acrilamida/química , Fluorescência , Lactoglobulinas/química , Triptofano/química , Concentração de Íons de Hidrogênio , Modelos Moleculares , Estrutura Molecular , Fatores de Tempo
13.
Int J Biol Macromol ; 36(3): 135-43, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15996729

RESUMO

This work aims to present a comprehensive study about the macroscopic characteristics of globular vegetable proteins, in terms of their gelling ability, by understanding their molecular behaviour, when submitted to a thermal gelling process. The gels of soy, pea and lupin proteins were characterized by rheological techniques. Gelation kinetics, mechanical spectra, as well as the texture of these gels were analyzed and compared. Additionally, capillary viscometry, steady-state fluorescence and fluorescence anisotropy were used to monitor the structural changes induced by the thermal denaturation, which constitutes the main condition for the formation of a gel structure. Based on these techniques it was possible to establish a relationship between the gelling ability of each protein isolate and their structural resistance to thermal unfolding, enabling us to explain the weakest and the strongest gelling ability observed for lupin and soy proteins isolates, respectively.


Assuntos
Proteínas/química , Verduras/metabolismo , Anisotropia , Globulinas/química , Temperatura Alta , Cinética , Lupinus , Substâncias Macromoleculares/química , Ervilhas/metabolismo , Proteínas de Vegetais Comestíveis/química , Desnaturação Proteica , Dobramento de Proteína , Reologia , Proteínas de Soja/química , Espectrometria de Fluorescência , Espectrofotometria , Propriedades de Superfície , Temperatura , Termodinâmica , Fatores de Tempo
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