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1.
Food Chem ; 346: 128742, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33373823

RESUMO

The use of poly-ß-hydroxybutyrate (PHB) is an alternative polymer that can be considered environment friendly and renewable to prepare nanoparticles of carotenoids. This study aimed to develop and characterize aqueous dispersion nanoparticles and lyophilized nanoparticles of carotenoid extract obtained from Spirulina sp. LEB 18 by nanoprecipitation, using poly d,l-lactic acid (PLA)/poly d,l-lactic-co-glycolic acid (PLGA) (75:25 w/w) or PHB as encapsulants. The samples were characterized for the particle size, polydispersity index, zeta potential, apparent viscosity, pH, color parameters, ultraviolet-visible (UV/Vis) spectrophotometry, carotenoid profile, encapsulation efficiency, morphology, and thermal analysis. Nanoparticles containing microalgae carotenoid extract showed average particle diameter on a nanoscale (<200 nm), high homogeneity and stability, high thermal stability, and encapsulation efficiency carotenoid (>80%) when compared to nanoparticles containing ß-carotene synthetic. PHB or PLA/PLGA as encapsulating material in the production of nanoparticles from microalgae carotenoids can be a polymeric alternative capable of promoting greater stability and application of carotenoids.


Assuntos
Carotenoides/farmacologia , Hidroxibutiratos/química , Nanopartículas/química , Poliésteres/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Spirulina/química , beta Caroteno/química , Carotenoides/isolamento & purificação , Portadores de Fármacos/química , Excipientes , Tamanho da Partícula
2.
Int J Mol Sci ; 21(24)2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-33353232

RESUMO

The utilization of keratin waste in new materials formulations can prevent its environmental disposal problem. Here, novel composites based on biodegradable blends consisting of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB), and filled with hydrolyzed keratin with loading from 1 to 20 wt % were prepared and their properties were investigated. Mechanical and viscoelastic properties were characterized by tensile test, dynamic mechanical thermal analysis (DMTA) and rheology measurements. The addition of acetyltributyl citrate (ATBC) significantly affected the mechanical properties of the materials. It was found that the filled PLA/PHB/ATBC composite at the highest keratin loading exhibited similar shear moduli compared to the un-plasticized blend as a result of the much stronger interactions between the keratin and polymer matrix compared to composites with lower keratin content. The differences in dynamic moduli for PLA/PHB/ATBC blend filled with keratin depended extensively on the keratin content while loss the factor values progressively decreased with keratin loading. Softening interactions between the keratin and polymer matrix resulted in lower glass transitions temperature and reduced polymer chain mobility. The addition of keratin did not affect the extent of degradation of the PLA/PHB blend during melt blending. Fast hydrolysis at 60 °C was observed for composites with all keratin loadings. The developed keratin-based composites possess properties comparable to commonly used thermoplastics applicable for example as packaging materials.


Assuntos
Hidroxibutiratos/química , Queratinas/química , Plastificantes/química , Poliésteres/química , Polímeros/química , Reologia , Temperatura
3.
J Vis Exp ; (160)2020 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-32628168

RESUMO

For biomedical applications, metal oxide nanoparticles such as iron oxide and manganese oxide (MnO), have been used as biosensors and contrast agents in magnetic resonance imaging (MRI). While iron oxide nanoparticles provide constant negative contrast on MRI over typical experimental timeframes, MnO generates switchable positive contrast on MRI through dissolution of MnO to Mn2+ at low pH within cell endosomes to 'turn ON' MRI contrast. This protocol describes a one-pot synthesis of MnO nanoparticles formed by thermal decomposition of manganese(II) acetylacetonate in oleylamine and dibenzyl ether. Although running the synthesis of MnO nanoparticles is simple, the initial experimental setup can be difficult to reproduce if detailed instructions are not provided. Thus, the glassware and tubing assembly is first thoroughly described to allow other investigators to easily reproduce the setup. The synthesis method incorporates a temperature controller to achieve automated and precise manipulation of the desired temperature profile, which will impact resulting nanoparticle size and chemistry. The thermal decomposition protocol can be readily adapted to generate other metal oxide nanoparticles (e.g., iron oxide) and to include alternative organic solvents and stabilizers (e.g., oleic acid). In addition, the ratio of organic solvent to stabilizer can be changed to further impact nanoparticle properties, which is shown herein. Synthesized MnO nanoparticles are characterized for morphology, size, bulk composition, and surface composition through transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. The MnO nanoparticles synthesized by this method will be hydrophobic and must be further manipulated through ligand exchange, polymeric encapsulation, or lipid capping to incorporate hydrophilic groups for interaction with biological fluids and tissues.


Assuntos
Hidroxibutiratos/química , Compostos de Manganês/química , Manganês/química , Nanopartículas Metálicas/química , Óxidos/química , Pentanonas/química , Temperatura , Vidro/química , Interações Hidrofóbicas e Hidrofílicas , Nanopartículas Metálicas/ultraestrutura , Nitrogênio/química , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Água/química , Difração de Raios X
4.
Food Chem ; 321: 126690, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244139

RESUMO

The current research article was reported the synthesis of a novel poly(3-hydroxy butyrate)-b-poly(vinyl benzyl xanthate) block copolymer (PHB-Xa) for vortex-assisted solid-phase microextraction of cobalt(II) and nickel(II) from canned foodstuffs prior to their determinations by flame atomic absorption spectrometry. The block copolymer was synthesized and characterized by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. Experimental variables affecting the extraction efficiency of the copolymer were optimized. Since the PHB-Xa block copolymers have a high π conjugate structure and hydrophobicity, the use of this adsorbent yielded quantitative results for the extraction of Ni(II) and Co(II). After optimization, the linearities for Ni(II) and Co(II) were 0.05-80 ng mL-1 and 0.2-100 ng mL-1, respectively. The limits of detection and the limits of quantification were in the range of 0.015-0.06 ng mL-1 and 0.05-0.2 ng mL-1, respectively. The method was successfully applied to determination of Ni(II) and Co(II) in canned foodstuffs prepared by microwave digestion.


Assuntos
Cobalto/isolamento & purificação , Análise de Alimentos/métodos , Níquel/isolamento & purificação , Polímeros/química , Microextração em Fase Sólida/métodos , Cobalto/análise , Contaminação de Alimentos , Alimentos em Conserva , Hidroxibutiratos/química , Limite de Detecção , Espectroscopia de Ressonância Magnética , Níquel/análise , Poliésteres/química , Polímeros/síntese química , Cloreto de Polivinila/química , Espectrofotometria Atômica/métodos , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Sci Rep ; 10(1): 2725, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-32066785

RESUMO

Superparamagnetic iron oxide nanoparticles (SPIONs) have been investigated for wide variety of applications. Their unique properties render them highly applicable as MRI contrast agents, in magnetic hyperthermia or targeted drug delivery. SPIONs surface properties affect a whole array of parameters such as: solubility, toxicity, stability, biodistribution etc. Therefore, progress in the field of SPIONs surface functionalization is crucial for further development of therapeutic or diagnostic agents. In this study, SPIONs were synthesized by thermal decomposition of iron (III) acetylacetonate Fe(acac)3 and functionalized with dihexadecyl phosphate (DHP) via phase transfer. Bioactivity of the SPION-DHP was assessed on SW1353 and TCam-2 cancer derived cell lines. The following test were conducted: cytotoxicity and proliferation assay, reactive oxygen species (ROS) assay, SPIONs uptake (via Iron Staining and ICP-MS), expression analysis of the following genes: alkaline phosphatase (ALPL); ferritin light chain (FTL); serine/threonine protein phosphatase 2A (PP2A); protein tyrosine phosphatase non-receptor type 11 (PTPN11); transferrin receptor 1 (TFRC) via RT-qPCR. SPION-DHP nanoparticles were successfully obtained and did not reveal significant cytotoxicity in the range of tested concentrations. ROS generation was elevated, however not correlated with the concentrations. Gene expression profile was slightly altered only in SW1353 cells.


Assuntos
Condrócitos/efeitos dos fármacos , Compostos Férricos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Nanopartículas de Magnetita/química , Organofosfatos/química , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Antígenos CD/genética , Antígenos CD/metabolismo , Apoferritinas/genética , Apoferritinas/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Condrócitos/citologia , Condrócitos/metabolismo , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Compostos Férricos/química , Humanos , Hidroxibutiratos/química , Pentanonas/química , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores da Transferrina/genética , Receptores da Transferrina/metabolismo , Succímero/química
6.
Molecules ; 25(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31906348

RESUMO

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-ß-hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the extracted polymer. The efficient marine bacterial isolates were identified by the phylogenetic analysis of the 16S rRNA genes as Tamlana crocina, Bacillus aquimaris, Erythrobacter aquimaris, and Halomonas halophila. The optimization of PHB accumulation by E. aquimaris was achieved at 120 h, pH 8.0, 35 °C, and 2% NaCl, using glucose and peptone as the best carbon and nitrogen sources at a C:N ratio of 9.2:1. The characterization of the extracted biopolymer by Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Gas chromatography-mass spectrometry (GC-MS) proves the presence of hydroxyl, methyl, methylene, methine, and ester carbonyl groups, as well as derivative products of butanoic acid, that confirmed the structure of the polymer as PHB. This is the first report on E. aquimaris as a PHB producer, which promoted the hypothesis that marine rhizospheric bacteria were a new area of research for the production of biopolymers of commercial value.


Assuntos
Biopolímeros/biossíntese , Biopolímeros/química , Hidroxibutiratos/química , Hidroxibutiratos/metabolismo , Poliésteres/química , Poliésteres/metabolismo , Sphingomonadaceae/química , Sphingomonadaceae/metabolismo , Avicennia/microbiologia , Bacillus/química , Bacillus/genética , Bacillus/metabolismo , Biopolímeros/análise , Carbono/química , Carbono/metabolismo , Fermentação , Flavobacteriaceae/química , Flavobacteriaceae/genética , Flavobacteriaceae/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Halomonas/química , Halomonas/genética , Halomonas/metabolismo , Hidroxibutiratos/análise , Espectroscopia de Ressonância Magnética , Nitrogênio/química , Nitrogênio/metabolismo , Filogenia , Poliésteres/análise , RNA Ribossômico 16S/genética , Rizosfera , Salinidade , Arábia Saudita , Água do Mar/microbiologia , Espectroscopia de Infravermelho com Transformada de Fourier , Sphingomonadaceae/genética , Sphingomonadaceae/isolamento & purificação , Temperatura
7.
PLoS One ; 15(1): e0220095, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31910206

RESUMO

There are numerous reports on poly-ß-hydroxybutyrate (PHB) depolymerases produced by various microorganisms isolated from various habitats, however, reports on PHB depolymerase production by an isolate from plastic rich sites scares. Although PHB has attracted commercial significance, the inefficient production and recovery methods, inefficient purification of PHB depolymerase and lack of ample knowledge on PHB degradation by PHB depolymerase have hampered its large scale commercialization. Therefore, to ensure the biodegradability of biopolymers, it becomes imperative to study the purification of the biodegrading enzyme system. We report the production, purification, and characterization of extracellular PHB depolymerase from Stenotrophomonas sp. RZS7 isolated from a dumping yard rich in plastic waste. The isolate produced extracellular PHB depolymerase in the mineral salt medium (MSM) at 30°C during 4 days of incubation under shaking. The enzyme was purified by three methods namely ammonium salt precipitation, column chromatography, and solvent purification. Among these purification methods, the enzyme was best purified by column chromatography on the Octyl-Sepharose CL-4B column giving optimum yield (0.7993 Umg-1mL-1). The molecular weight of purified PHB depolymerase was 40 kDa. Studies on the assessment of biodegradation of PHB in liquid culture medium and under natural soil conditions confirmed PHB biodegradation potential of Stenotrophomonas sp. RZS7. The results obtained in Fourier-Transform Infrared (FTIR) analysis, High-Performance Liquid Chromatography (HPLC) study and Gas Chromatography Mass-Spectrometry (GC-MS) analysis confirmed the biodegradation of PHB in liquid medium by Stenotrophomonas sp. RZS7. Changes in surface morphology of PHB film in soil burial as observed in Field Emission Scanning Electron Microscopy (FESEM) analysis confirmed the biodegradation of PHB under natural soil environment. The isolate was capable of degrading PHB and it resulted in 87.74% biodegradation. A higher rate of degradation under the natural soil condition is the result of the activity of soil microbes that complemented the biodegradation of PHB by Stenotrophomonas sp. RZS7.


Assuntos
Proteínas de Bactérias/química , Hidrolases de Éster Carboxílico/química , Hidroxibutiratos/química , Plásticos/química , Poliésteres/química , Poluentes do Solo/química , Stenotrophomonas/enzimologia , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/isolamento & purificação , Biodegradação Ambiental , Hidrolases de Éster Carboxílico/biossíntese , Hidrolases de Éster Carboxílico/isolamento & purificação , Cromatografia de Afinidade , Meios de Cultura/química , Humanos , Hidrólise , Peso Molecular , Solo/química , Resíduos Sólidos , Stenotrophomonas/química
8.
Food Chem ; 313: 126134, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31927208

RESUMO

This study aimed to develop an active film by using biodegradable materials and antioxidant essential oils to improve gas and water vapor permeability during peach preservation. O2 and CO2 volume fractions and water status were investigated by using an oxygen meter and conducting low-field nuclear magnetic resonance (LF-NMR), respectively. Results revealed that the film added with angelica essential oil (AEO) had a 49.4% increase in 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and high O2 and CO2 transmission rates and water vapor permeability. The film added with AEO showed the best preservation effect, effectively delaying the oxidation of peach, maintained the combined water, and extended the shelf life of peaches to more than 15 days. This study provided a relatively new LF-NMR method for tracking the internal water status of packaged peaches and served as an effective reference for the development of active food packaging.


Assuntos
Embalagem de Alimentos/instrumentação , Hidroxibutiratos/química , Óleos Voláteis/química , Poliésteres/química , Prunus persica , Angelica/química , Antioxidantes/química , Catecol Oxidase/metabolismo , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Armazenamento de Alimentos , Lipoxigenase/metabolismo , Espectroscopia de Ressonância Magnética , Óleos Voláteis/farmacologia , Oxirredução , Oxigênio , Permeabilidade , Proteínas de Plantas/metabolismo , Prunus persica/metabolismo , Vapor
9.
ACS Appl Mater Interfaces ; 12(1): 217-226, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31804796

RESUMO

Magnetic nanoparticles are critical to a broad range of applications from medical diagnostics and therapeutics to biotechnological processes and single-molecule manipulation. To advance these applications, facile and robust routes to synthesize highly magnetic nanoparticles over a wide size range are needed. Here, we demonstrate that changing the degassing temperature of thermal decomposition of metal acetylacetonate precursors from 90 to 25 °C tunes the size of ferrimagnetic ZnxFe3-xO4 nanocubes from 25 to 100 nm, respectively. We show that degassing at 90 °C nearly entirely removes acetylacetone ligands from the reaction, which results in an early formation of monomers and a reaction-controlled growth following LaMer's model toward small nanocubes. In contrast, degassing at 25 °C only partially dissociates acetylacetone ligands from the metal center and triggers a delayed formation of monomers, which leads to intermediate assembled structures made of tiny irregular crystallites and an eventual formation of large nanocubes via a diffusion-controlled growth mechanism. Using complementary techniques, we determine the substitution fraction x of Zn2+ to be in the range of 0.35-0.37. Our method reduces the complexity of the thermal decomposition method by narrowing the synthesis parameter space to a single physical parameter and enables fabrication of highly magnetic and uniform zinc ferrite nanocubes over a broad size range. The resulting particles are promising for a range of applications from magnetic fluid hyperthermia to actuation of macromolecules.


Assuntos
Compostos Férricos/química , Hidroxibutiratos/química , Nanoestruturas/química , Pentanonas/química , Compostos de Zinco/química , Ligantes
10.
ACS Appl Mater Interfaces ; 12(5): 5578-5592, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31886639

RESUMO

Growth factor incorporation in biomedical constructs for their local delivery enables specific pharmacological effects such as the induction of cell growth and differentiation. This has enabled a promising way to improve the tissue regeneration process. However, it remains challenging to identify an appropriate approach that provides effective growth factor loading into biomedical constructs with their following release kinetics in a prolonged manner. In the present work, we performed a systematic study, which explores the optimal strategy of growth factor incorporation into sub-micrometric-sized CaCO3 core-shell particles (CSPs) and hollow silica particles (SiPs). These carriers were immobilized onto the surface of the polymer scaffolds based on polyhydroxybutyrate (PHB) with and without reduced graphene oxide (rGO) in its structure to examine the functionality of incorporated growth factors. Bone morphogenetic protein-2 (BMP-2) and ErythroPOietin (EPO) as growth factor models were included into CSPs and SiPs using different entrapping strategies, namely, physical adsorption, coprecipitation technique, and freezing-induced loading method. It was shown that the loading efficiency, release characteristics, and bioactivity of incorporated growth factors strongly depend on the chosen strategy of their incorporation into delivery systems. Overall, we demonstrated that the combination of scaffolds with drug delivery systems containing growth factors has great potential in the field of tissue regeneration compared with individual scaffolds.


Assuntos
Proteína Morfogenética Óssea 2/química , Portadores de Fármacos/química , Eritropoetina/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Proteína Morfogenética Óssea 2/metabolismo , Proteína Morfogenética Óssea 2/farmacologia , Carbonato de Cálcio/química , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Eritropoetina/metabolismo , Eritropoetina/farmacologia , Grafite/química , Humanos , Hidroxibutiratos/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Osteoblastos/citologia , Osteoblastos/metabolismo , Osteogênese/efeitos dos fármacos , Poliésteres/química , Dióxido de Silício/química
11.
Int J Biol Macromol ; 144: 47-52, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31812746

RESUMO

Polyhydroxybutyrate (PHB) is biodegradable and biocompatible polyester that has been recently used for developing different drug delivery systems (DDS). Microspheres as DDS, consist of a polymeric matrix with a diameter of 1-125 µm which contains a substance entrapped, and then released mainly through diffusion. In order to make DDS viable for commercial applications, it is essential to develop models that describe and predict the substance release kinetic. In this study, microspheres of PHB with curcumin entrapped were synthesized; the release of curcumin was studied and modeled. As a first approach, a physical model was introduced, in which mass transference was considered analogous to heat transference. The proposed model was based on local mass balance through the classical diffusion equation and total mass balance imposed through an integro-differential equation. The total mass balance introduced nonlinearities in the dynamics of the drug within the fluid; therefore, a semi-analytical approach based on the heat balance integral method was applied to solve the proposed model. Finally, by using the experimental rate of release of curcumin, the semi-analytical solutions to the proposed model were compared with the experimental release data, showing the importance of adding mass balance in the nonlinear mathematical model in order to describe more accurately the release kinetics.


Assuntos
Curcumina/farmacologia , Liberação Controlada de Fármacos , Hidroxibutiratos/química , Microesferas , Modelos Químicos , Difusão , Análise Numérica Assistida por Computador , Tamanho da Partícula , Propriedades de Superfície , Fatores de Tempo
12.
Carbohydr Polym ; 227: 115341, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590874

RESUMO

Starch nanocrystal (SNC), was used as the third component to prepare nanocomposites with biodegradable poly(ß-hydroxybutyrate)/poly(butylene succinate) (PHB/PBS) blend. The results reveal that SNC shows strong nucleation to the two matrix polymers. However, the crystallization temperature of PHB is highly dependent on the SNC loadings, whereas that of PBS not. This is because SNCs have preferential localization in the immiscible matrix polymers: mainly dispersed in the continuous PHB phase and on PHB/PBS phase interfaces. Therefore, alteration trend of crystallization temperatures can be used as good probe to evaluate selective localization of SNCs in the immiscible blends containing two semicrystalline polymers. The nucleation activities of SNCs, and their interaction energy densities in the two polyesters, as well as the tensile behaviors of ternary nanocomposites, were then detected, aiming at establishing a simple route to prepare green nanocomposites with tailorable multi-phase morphology and balanced mechanical properties using starch and biodegradable aliphatic polyester blends.


Assuntos
Butileno Glicóis/química , Hidroxibutiratos/química , Nanocompostos/química , Nanopartículas/química , Poliésteres/química , Polímeros/química , Amido/química , Cristalização , Temperatura
13.
Z Naturforsch C J Biosci ; 75(1-2): 7-12, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31639104

RESUMO

6-Tuliposides A (6-PosA) and B (6-PosB) are major defensive secondary metabolites in tulip cultivars (Tulipa gesneriana), having an acyl group at the C-6 position of d-glucose. Although some wild tulip species produce 1,6-diacyl-glucose type of Pos (PosD and PosF), as well as 6-PosA/B, they have not yet been isolated from tulip cultivars. Here, aiming at verifying the presence of PosD and PosF in tulip cultivars, tissue extracts of 25 cultivars were analyzed by high-performance liquid chromatography (HPLC). Although no HPLC peaks for PosD nor PosF were detected in most cultivars, we found two cultivars giving a minute HPLC peak for PosD and the other two cultivars giving that for PosF. PosD and PosF were then purified from petals of cultivar 'Orca' and from pistils of cultivar 'Murasakizuisho', respectively, and their identities were verified by spectroscopic analyses. This is the first report that substantiates the presence of 1,6-diacyl-glucose type of Pos in tulip cultivars.


Assuntos
Glucose/química , Glucosídeos/química , Oxibato de Sódio/análogos & derivados , Tulipa/química , Cromatografia Líquida de Alta Pressão , Flores/química , Glucose/análogos & derivados , Glucosídeos/isolamento & purificação , Glicosídeos/química , Hidroxibutiratos/química , Oxibato de Sódio/química , Oxibato de Sódio/isolamento & purificação
14.
Biomater Sci ; 8(3): 926-936, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31833480

RESUMO

Transparency is an important criterion for the application of biomaterials to the eye and essential for use as a vitreous substitute. However, there is a lack of understanding on the features of transparent hydrogels and the boundaries of transparency of various hydrogel systems. In this paper, we tune the poly[(R)-3-hydroxybutyrate-(R)-3-hydroxyhexanoate] (PHBHx) content of biodegradable PHBHx-based polyurethane thermogels and show that the amount of hydrophobic PHBHx correlates with hydrogel cloudiness. We found that PHxEP-0.5 hydrogel shows high light transmittance and suitable gel properties as a vitreous substitute. The PHxEP-0.5 hydrogel is able to maintain transparency when implanted in rabbit eyes as opposed to a cloudy gel and shows negligible inflammation and preservation of the retinal structure over 6 months. In conclusion, we show that PHBHx-based thermogels can be tuned for transparency and are biocompatible in the rabbit eye. These results could be instructive for the design of a new generation of injectable transparent vitreous substitutes.


Assuntos
Materiais Biocompatíveis/química , Poli-Hidroxialcanoatos/química , Corpo Vítreo/química , Animais , Hidrogéis/química , Interações Hidrofóbicas e Hidrofílicas , Hidroxibutiratos/química , Masculino , Camundongos , Poliésteres/química , Próteses e Implantes , Coelhos
15.
Biotechnol J ; 14(12): e1900201, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31703147

RESUMO

The biodegradable polyester 3-hydroxybutyrate (3HB) polymer [P(3HB)] is intracellularly synthesized and accumulated in recombinant Escherichia coli. In this study, native polyhydroxyalkanoate (PHA) synthases are used to attempt to microbially secrete 3HB homo-oligomers (3HBOs), which are widely distributed in nature as physiologically active substances. High secretory production is observed, especially for the two PHA synthases from Aeromonas caviae and Bacillus cereus YB4. Surprisingly, an ethyl ester at the carboxy terminus (ethyl ester form) of 3HBOs is identified for most of the PHA synthases tested. Next, 3HBOs with a functional carboxyl group (carboxyl form of 3HBO) are obtained by using the alcohol dehydrogenase gene (adhE)-deficient mutant strain, suggesting that the endogenous ethanol produced in E. coli acts as a chain transfer (CT) agent in the generation of 3HBOs. Furthermore, an in vitro polymerization assay reveals that CT agents such as ethanol and free 3HB are involved in the generation of ethyl ester and carboxyl form of 3HBO, respectively. The microbial platform established herein allows the secretion of 3HBOs with desirable end structures by supplementation with various CT agents. The obtained 3HBOs and their end-capped forms may be used as physiologically active substances and building blocks for polymeric materials.


Assuntos
Ácido 3-Hidroxibutírico/biossíntese , Ácido 3-Hidroxibutírico/química , Aciltransferases/metabolismo , Poli-Hidroxialcanoatos/biossíntese , Poli-Hidroxialcanoatos/química , Ácido 3-Hidroxibutírico/isolamento & purificação , Aciltransferases/genética , Aeromonas caviae/enzimologia , Aeromonas caviae/genética , Álcool Desidrogenase/genética , Bacillus cereus/enzimologia , Bacillus cereus/genética , Biodegradação Ambiental , Escherichia coli/genética , Escherichia coli/metabolismo , Etanol/metabolismo , Hidroxibutiratos/química , Peso Molecular , Poliésteres/química , Polimerização , Proteínas Recombinantes , Recombinação Genética , Fatores de Tempo
16.
J Chromatogr B Analyt Technol Biomed Life Sci ; 1134-1135: 121876, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31783252

RESUMO

In this work, the physical and chemical properties of a novel zwitterionic LC stationary phase are applied to the development, validation and application of a new fast and reliable method devoted to the analysis of GHB (gamma-hydroxybutyric acid) and its relatively new discovered glucuronide metabolite in hair. The obtained sensitivity, expressed as limit of detection (LOD) and quantification (LOQ), were 0.033 and 0.10 ng/mg for GHB and 0.11 and 0.37 ng/mg, for GHB-glucuronide respectively. Linearity was assessed between LOQ and 50 ng/mg for both compounds. GHB and GHB-glucuronide extraction from hair matrix was maintained simple and consisted in an acidified-solvent incubation. No samples purification was required before LC-MS/MS analysis. The method was finally applied to 65 real hair sample, 60 adults and 5 children below 2 years old. The obtained results highlighted that GHB concentrations were in the range 0.11-0.96 ng/mg (average 0.38 ±â€¯0.25 ng/mg) in 44 cases (68%) while in 21 samples GHB concentrations were in the range between LOD and LOQ (0.033-0.1 ng/mg). GHB-glucuronide was detected in few samples (n. 3) at levels below LOQ. The interest on these molecules relies on the fact that GHB is both a naturally occurring inhibitory neurotransmitter in the central nervous system and an illicit drug often experienced by victims of drug-facilitated sexual assault. GHB-glucuronide was firstly identified in urine by the group of Petersen in 2013 and, as per analogy to ethyl glucuronide, it was proposed as a longer biomarker for GHB intoxication.


Assuntos
Cromatografia Líquida/métodos , Cabelo/química , Hidroxibutiratos/análise , Adulto , Feminino , Toxicologia Forense , Glucuronídeos/análise , Glucuronídeos/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Hidroxibutiratos/química , Lactente , Limite de Detecção , Modelos Lineares , Masculino , Espectrometria de Massas , Reprodutibilidade dos Testes , Delitos Sexuais
17.
mSphere ; 4(5)2019 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-31619503

RESUMO

Gellan gum is a microbial exopolysaccharide, produced after aerobic fermentation using the Gram-negative bacterium strain Sphingomonas elodea ATCC 31461. Due to its unique structure and excellent physical characteristics, gellan gum has a broad range of applications in food, pharmaceutical, and other industries where it is used for stabilizing, emulsifying, thickening, and suspending. During the fermentative production of gellan, strain ATCC 31461 also accumulates large amounts of the metabolic by-products yellow carotenoid pigments and poly-ß-hydroxybutyrate (PHB), which is decreasing the gellan production and increasing processing costs. A pigment PHB-free mutant was obtained by knocking out the phytoene desaturase gene (crtI) in the carotenoid biosynthetic pathway and the phaC gene, encoding a PHB synthase for the polymerization of PHB. Unfortunately, the double gene knockout mutant produced only 0.56 g liter-1 gellan. Furthermore, blocking PHB and carotenoid synthesis resulted in the accumulation of pyruvate, which reduced gellan production. To elevate gellan production, combined UV irradiation and ethyl methanesulfonate (EMS) mutagenesis treatment were used. A mutant strain with the same level of pyruvate as that of the wild-type strain and higher gellan production was isolated (1.35 g liter-1, 132.8% higher than the double gene knockout mutant and 14.4% higher than the wild-type strain ATCC 31461). In addition, a new gellan gum recovery method based on the new mutant strain was investigated, in which only 30% isopropanol was required, which is twice for the wild-type strains, and the performance of the final product was improved. Thus, the mutant strain could be an ideal strain for the commercial production of gellan.IMPORTANCE A carotenoid- and PHB-free double gene knockout strain mutant was constructed to simplify the purification steps normally involved in gellan production. However, the production of gellan gum was unexpectedly reduced. A mutant with 14.4% higher gellan production than that of the wild-type strain was obtained and isolated after employing UV and EMS combined mutagenesis. Based on this high-yield and low-impurity-producing mutant, a new recovery method requiring less organic solvent and fewer operating steps was developed. This method will effectively reduce the production costs and improve the economic benefits of large-scale gellan production.


Assuntos
Microbiologia Industrial/métodos , Polissacarídeos Bacterianos/biossíntese , Sphingomonas/genética , Carotenoides/química , Metanossulfonato de Etila/farmacologia , Fermentação , Técnicas de Inativação de Genes , Hidroxibutiratos/química , Mutação , Poliésteres/química , Sphingomonas/química , Sphingomonas/efeitos dos fármacos , Sphingomonas/efeitos da radiação , Raios Ultravioleta
18.
ACS Synth Biol ; 8(11): 2483-2493, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31603652

RESUMO

Formaldehyde (HCHO) is an important intermediate in the metabolism of one-carbon (C1) compounds such as methanol, formate, and methane. The ribulose monophosphate (RuMP) pathway is the most-studied HCHO assimilation route and the 3-hexulose-6-phosphate synthase (Hps) plays an important role for HCHO fixation. In this study, we proposed and selected a pyruvate-dependent aldolase to channel HCHO into 2-keto-4-hydroxybutyrate as an important intermediate for biosynthesis. By combining this reaction with three further enzymes we demonstrated a pyruvate-based C1 metabolic pathway for biosynthesis of the appealing compound 1,3-propanediol (1,3-PDO). This novel pathway is first confirmed in vitro using HCHO and pyruvate as substrates. It is then demonstrated in vivo in E. coli for 1,3-PDO production from HCHO and methanol with glucose as a cosubstrate. This de novo pathway has several decisive advantages over the known metabolic pathways for 1,3-PDO: (1) C1 carbon is directly channeled into a precursor of 1,3-PDO; (2) the use of pyruvate as an acceptor of HCHO is glycerol-independent, circumventing thus the need of coenzyme B12 as cofactor for glycerol dehydration; (3) the pathway is much shorter and more simple than the recently proposed l-homoserine-dependent pathway, thus avoiding complicated regulations involving precursors for essential amino acids. In addition to proof-of-concept we further improved the host strain by deleting a gene (frmA) responsible for the conversion of HCHO to formate, thereby increasing the production of 1,3-PDO from 298.3 ± 11.4 mg/L to 508.3 ± 9.1 mg/L and from 3.8 mg/L to 32.7 ± 0.8 mg/L with HCHO and methanol as cosubstrate of glucose fermentation, respectively. This work is the first study demonstrating a genetically engineered E. coli that can directly use HCHO or methanol for the synthesis of 2-keto-4-hydroxybutyrate and its further conversion to 1,3-PDO.


Assuntos
Escherichia coli/metabolismo , Formaldeído/metabolismo , Frutose-Bifosfato Aldolase/metabolismo , Hidroxibutiratos/metabolismo , Cetonas/metabolismo , Metanol/metabolismo , Propilenoglicóis/metabolismo , Aldeído Oxirredutases/deficiência , Aldeído Oxirredutases/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Formaldeído/química , Frutose-Bifosfato Aldolase/genética , Glucose/metabolismo , Hidroxibutiratos/química , Cetonas/química , Cinética , Redes e Vias Metabólicas , Metanol/química , Propilenoglicóis/química , Ácido Pirúvico/metabolismo , Especificidade por Substrato
19.
Int J Nanomedicine ; 14: 6869-6889, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31507318

RESUMO

Introduction: Biodegradable polymers that contain radioactive isotopes such as Holmium 166 have potential applications as beta particle emitters in tumor tissues. Also, Ho(III) is paramagnetic, which makes it suitable as a contrast agent for magnetic resonance (MR) images. Methods: Holmium acetylacetonate (Ho(acac)3) loaded poly(3-hydroxy-butyrate-co-3-hydroxy-valerate) microspheres, with 5% or 8% of 3-hydroxy-valerate (HV), were prepared by emulsification/evaporation process within 20-53 µm size. Microspheres characterization was done using scanning electron microscopy, energy-dispersive X-ray, and infrared spectroscopies. The release of holmium(III) in sodium phosphate buffer (pH 7.4) was followed for 9 days with inductively coupled plasma. Finally, T2 and T2* magnetic resonance images (MRI) were acquired and compared with the MRI of the inclusion complex of holmium acetylacetonate in some ß-cyclodextrins. Results: Holmium acetylacetonate loading, evaluated by thermogravimetry, was up to 20 times higher for copolymer with 5% of HV. It was shown that microspheres loaded with Ho(acac)3 exhibited an accumulation of Ho(III) on their surfaces but were stable over time, as no expressive release of holmium(III) was detected in 9-day exposition to sodium phosphate buffer. Holmium acetylacetonate in both microspheres or inclusion complexes was very efficient in obtaining T2 and T2* weighted images in magnetic resonance, thus, might be used as contrast agents. Conclusion: This is the first description of the use of inclusion complexes of holmium acetylacetonate in biodegradable polymers as contrast agents. New investigations are underway to evaluate the resistance of PHB-HV polymer microparticles to nuclear activation to assess their potential for use as radiopharmaceuticals for the treatment of liver cancer.


Assuntos
Meios de Contraste/química , Hólmio/química , Hidroxibutiratos/química , Imagem por Ressonância Magnética , Microesferas , Pentanonas/química , Poliésteres/química , Radioisótopos/química , Calibragem , Humanos , Espectrometria por Raios X , Termogravimetria , Difração de Raios X
20.
Carbohydr Polym ; 223: 115131, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31426964

RESUMO

Biodegradable multicomponent films based on poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB) plasticized with oligomeric lactic acid (OLA), reinforced with synthetized cellulose nanocrystals (CNC) and modified by a natural additive with antimicrobial activity (carvacrol) were formulated and processed by extrusion. Morphological, mechanical, thermal, migration and barrier properties were tested to determine the effect of different components in comparison with neat poly(lactic acid). Results showed the positive effect of CNC in the five components based films, with the increase of the Young's modulus of the PLA_PHB_10Carv_15OLA, associated with an increase in the elongation at break (from 150% to 410%), by showing an OTR reduction of 67%. Disintegrability in compost conditions and enzymatic degradation were tested to evaluate the post-use of these films. All formulations disintegrated in less than 17 days, while proteinase K preferentially degraded the amorphous regions, and crystallinity degree of the nanocomposite films increased as a consequence of enzyme action.


Assuntos
Cimenos/química , Hidroxibutiratos/química , Ácido Láctico/química , Nanopartículas/química , Poliésteres/química , Celulose/química , Tamanho da Partícula , Propriedades de Superfície
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