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► Lippia sidoides essential oil was successfully encapsulated in a cashew gum/chitosan polymeric matrix. ► Nanoparticle sizes ranged from 335nm to 558nm, mainly with unimodal ...distribution and positive potential zeta values. ► Oil presence in nanoparticles was corroborated by FTIR and bioassays. ► Nanoparticles were effective in killing larvae of dengue vector, in a sustained release fashion.
Nanogels based on chitosan and cashew gum were prepared and loaded with Lippia sidoides oil. Several parameters such as cashew gum concentration and relative oil content in the matrix had their influence on nanogel properties investigated. Nanogels were characterized regarding their morphologies, particle size distributions, zeta potential, Fourier transform infrared spectroscopy and essential oil contents. The release profile was investigated by UV/vis spectroscopy and its efficacy was determined through bioassays. Results showed that samples designed using relative ratios matrix:oil 10:2, gum:chitosan 1:1 and 5% gum concentration showed high loading (11.8%) and encapsulation efficiency (70%). Nanogels were found to exhibit average sizes in the range 335–558nm. In vitro release profiles showed that nanoparticles presented slower and sustained release. Bioassays showed that larval mortality was related mainly to oil loading, with samples presenting more effective larvicide efficacies than the pure L. sidoides oil.
Objective
To estimate the incidence of epilepsy in children with Zika‐related microcephaly in the first 24 months of life; to characterize the associated clinical and electrographic findings; and to ...summarize the treatment responses.
Methods
We followed a cohort of children, born during the 2015‐2016 Zika virus (ZIKV) epidemic in Brazil, with congenital microcephaly and evidence of congenital ZIKV infection on neuroimaging and/or laboratory testing. Neurological assessments were performed at ≤3, 6, 12, 15, 18, 21, and 24 months of life. Serial electroencephalograms were performed over the first 24 months.
Results
We evaluated 91 children, of whom 48 were female. In this study sample, the cumulative incidence of epilepsy was 71.4% in the first 24 months, and the main type of seizure was infantile spasms (83.1%). The highest incidence of seizures occurred between 3 and 9 months of age, and the risk remained high until 15 months of age. The incidence of infantile spasms peaked between 4 and 7 months and was followed by an increased incidence of focal epilepsy cases after 12 months of age. Neuroimaging results were available for all children, and 100% were abnormal. Cortical abnormalities were identified in 78.4% of the 74 children evaluated by computed tomography and 100% of the 53 children evaluated by magnetic resonance imaging. Overall, only 46.1% of the 65 children with epilepsy responded to treatment. The most commonly used medication was sodium valproate with or without benzodiazepines, levetiracetam, phenobarbital, and vigabatrin.
Significance
Zika‐related microcephaly was associated with high risk of early epilepsy. Seizures typically began after the third month of life, usually as infantile spasms, with atypical electroencephalographic abnormalities. The seizure control rate was low. The onset of seizures in the second year was less frequent and, when it occurred, presented as focal epilepsy.
Essential oil containing ALG/CG nanoparticles.
•Alginate/cashew gum nanoparticles were used for encapsulation of an essential oil•Particles have sizes in the range 223–399nm and zeta potential from ...−30 to −36mV•FTIR provided evidence of oil encapsulation and biopolymer and LS oil presences•X-ray and TGA/DSC revealed the good miscibility of both alginate and cashew gum•A release profile over 30h was achieved, whereby circa 95% of oil was released
Alginate/cashew gum nanoparticles were prepared via spray-drying, aiming at the development of a biopolymer blend for encapsulation of an essential oil. Nanoparticles were characterized regarding to their hydrodynamic volume, surface charge, Lippia sidoides essential oil content and release profile, in addition to being analyzed by infrared spectroscopy (FT-IR), thermal analysis (TGA/DSC) and X-ray diffractometry. Nanoparticles in solution were found to have averaged sizes in the range 223–399nm, and zeta potential values ranging from −30 to −36mV. Encapsulated oil levels varied from 1.9 to 4.4% with an encapsulation efficiency of up to 55%. The in vitro release profile showed that between 45 and 95% of oil was released within 30–50h. Kinetic studies revealed that release pattern follow a Korsmeyer–Peppas mechanism.
Chitosan (CH) was N-alkylated via Schiff base formation and further reduced via sodium borohydride. The reaction was carried out at room temperature, in a homogeneous aqueous medium, using as a ...source of alkyl group an essential oil (Eucalyptus staigeriana) containing an unsaturated aldehyde (3,7-dimethylocta-2,6-dienal). Derivatives were characterized by Infrared Spectroscopy, proton and carbon Nuclear Magnetic Resonance, XRD, particle size distribution and zeta potential. Chitosan hydrophobization evidence was given by FTIR as new bands at 2929 cm−1 due to methyl groups, along with the presence of strong band at 1580 cm−1 owing to N substitution. Moreover, carbon and proton NMR corroborated the insertion of methyl groups in chitosan backbone. The degree of substitution was found to be in the range 0.69–1.44. X-ray diffractograms revealed that the insertion of alkyl substituents in chitosan backbone led to a less crystalline material. Data from antibacterial activity revealed that chitosan and derivatives were effective against Gram-positive bacteria, whereby derivatives exhibited greater inhibitory effect than CH. Derivatives are likely candidates for use as carriers for active principles of interest of food, pharmacy and medicine.
•Essential oil was used as a sole source of alkyl group.•Chitosan derivatives were found to bear unsaturated alkyl groups.•Particle sizes in aqueous medium ranged from 160 to 199 nm.•Chitosan derivatives exhibit antibacterial activities.
► Polysaccharide from marine alga Gracilaria caudata (PGC) was recovery with 32.8% of yield. ► Characterization was performed by microanalysis, FT-IR and NMR spectroscopy. ► The structure is ...constituted by β-d-galactopyranose and 6-α-l-anhydrogalactose. ► Methyl and pyruvic acid groups were also detected.
Seaweeds are considered an important source of bioactive molecules. In this work the marine red alga Gracilaria caudata was submitted to aqueous extraction of their polysaccharides for 2h at 100°C. The polysaccharide fraction (PGC) presented a recovery of 32.8%. The sulfate content of PGC, calculated by S%, is 1±0.2% and the degree of sulfation accounts for 0.13±0.2. High-Performance Size-Exclusion Chromatography demonstrated that PGC consists of a high molecular weight polysaccharide (2.5×105gmol−1). Chemical analysis of PGC was performed by microanalysis, infrared (FT-IR) and nuclear magnetic resonance (NMR, 1 and 2D) spectroscopy. The structure of PGC is mainly constituted by the alternating residues 3-linked-β-d-galactopyranose and 4-linked-3,6-α-l-anhydrogalactose; however some hydroxyl groups were substituted by methyl groups and pyruvic acid acetal. The biological precursor of 3,6-α-l-anhydrogalactose (6-sulfate-α-l-galactose) was also detected.
Oxidized Cashew Gum Scaffolds for Tissue Engineering Maciel, Jeanny S.; Azevedo, Sara; Correia, Clara R. ...
Macromolecular materials and engineering,
March 2019, 2019-03-00, 20190301, Letnik:
304, Številka:
3
Journal Article
Recenzirano
In the last few years, several strategies have been proposed to fabricate scaffolds for tissue engineering (TE) applications; however, they are based on harsh and time‐consuming techniques. The ...choice for natural polymers such as cashew gum (CG) allows to circumvent the demands of biocompatibility and degradability of TE systems. In this work, CG, a polysaccharide derived from Anacardium occidentale trees, is functionalized with aldehyde groups through periodate oxidation. The resultant oxidized cashew gum (CGO) is mixed with gelatin (GE) to yield a covalently crosslinked hydrogel. CGO/GE sponges are obtained by employing a freeze‐drying methodology to the previously obtained hydrogels. The mechanical properties, swelling ability, and porosity of the GE/CGO sponges are tuned by using CGO with different degrees of oxidation. The resultant sponges can maintain high levels of water absorption and recover their initial mechanical properties after cyclic compression. Moreover, these porous and mechanically robust devices can support the adhesion and proliferation of cells, which can envision their application for the regeneration of soft tissues.
Scaffolds with enhanced mechanical and biological properties are fabricated by freeze‐drying hydrogels made of cashew gum and gelatin. The resultant constructs are able to recover their initial structure after successive compression cycles and to maintain high cell viability rates up to 25 days of culture, highlighting their potential for the regeneration of soft tissues.
Given its many potential applications, cashew gum hydrophobic derivatives have gained increasing attraction in recent years. We report here the effect of acyl chain length on hydrophobized cashew gum ...derivatives, using acetic, propionic, and butyric anhydrides on self-assembly nanoparticle properties and amphotericin B delivery. Nanoparticles with unimodal particle size distribution, highly negative zeta potential, and low PDI were produced. Butyrate cashew gum nanoparticles presented smaller size (<~100 nm) than acetylated and propionate cashew gum nanoparticles and no cytotoxicity in murine fibroblast cells was observed up to 100 µg/mL for loaded and unloaded nanoparticles. As a proof of concept of the potential use of the developed nanoparticle as a drug carrier formulation, amphotericin B (AmB) was encapsulated and fully characterized in their physicochemical, AmB association and release, stability, and biological aspects. They exhibited average hydrodynamic diameter lower than ~200 nm, high AmB efficiency encapsulations (up to 94.9%), and controlled release. A decrease in AmB release with the increasing of the anhydride chain length was observed, which explains the differences in antifungal activity against Candida albicans strains. An excellent storage colloidal stability was observed for unloaded and loaded AmB without use of surfactant. Considering the AmB delivery, the acyl derivative with low chain length is shown to be the best one, as it has high drug loading and AmB release, as well as low minimum inhibitory concentration against Candida albicans strains.
Tree-exuded gums are natural polymers that represent an abundant raw material in the food and pharmaceutical industries. The cashew gum can be obtained by exudation of trees of the genus Anacardium, ...a native species of the Brazilian northeast; its polymer consists of monosaccharide units propitious to the action of chemical reactions that tend to improve their intrinsic characteristics among them, as the degree of hydro-solubility. The objective of this work was to modify the exudate gum of Anacardium occidentale (cashew gum (CG)) through an amine reaction. The modification was confirmed by Nuclear Magnetic Resonance (1H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), zeta potential, and thermogravimetric analysis (TG). In addition, the chemical modification altered the molar mass and surface charge of the CG, and the amino group binding to the CG polymers was confirmed by FTIR spectra. In addition, cytotoxicity tests were performed where cell viability was estimated by an MTT assay on RAW 264.7 macrophages. Through these tests, it was found that the amine caused an increase in the thermal stability of the amino compounds and did not present cytotoxic potential at concentrations below 50.0 mg/L.
Stimulus-responsive nanoparticles stand out in studies for cancer treatment since these systems can promote a selective release of the drug in tumor tissues and cells, minimizing the effects caused ...by conventional chemotherapy. Dextran-graft-poly (N-isopropylacrylamide) copolymers were synthesized via Schiff base formation. The synthesis of copolymers was confirmed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (NMR) and the analyses of dynamic light scattering (DLS) showed that the copolymers were thermal and pH dual-responsive. The chemotherapy drug doxorubicin (DOX) was conjugated to the copolymers via Schiff base formation, obtaining nanoparticles by self-assembling with size smaller than 130 nm. A higher percentage of doxorubicin was released at pH 5.0 (59.1 ± 2.1%) compared to physiological pH (34.9 ± 4.8%), confirming a pH-sensitive release profile. The in vitro cytotoxicity assay demonstrated that DOX-loaded nanoparticles can inhibit cancer cell proliferation and promote reduced cytotoxicity in non-tumor cells. The D45kP30k-DOX nanoparticles induced morphological changes in HCT-116 cells suggesting cell death and the cell uptake assay indicated that the nanoparticles can be internalized by endocytosis. Therefore, DOX-loaded nanoparticles exhibited potential as smart systems for cancer treatment.
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•Novel heterofunctional SPMN@PEI-DVS supports were prepared.•TLL was immobilized onto SPMN@PEI-DVS by multipoint covalent attachment.•The functionalization and activation was ...confirmed by several techniques.•TLL properties were improved after immobilization.•The prepared nanobiocatalysts were active in hydrolysis and acetylation reactions.
Lipase from Thermomyces lanuginosus (TLL) was immobilized onto a novel heterofunctional support, divinyl sulfone (DVS) superparamagnetic nanoparticles (SPMNs) functionalized with polyethyleneimine (PEI). Particle size and zeta potential measurements, elemental analysis, X-ray powder diffraction, magnetic measurements, and infrared spectroscopy analysis were used to characterize the TLL preparations. At pH 10, it was possible to achieve 100 % of immobilization yield in 1 h. The immobilization pH gives TLL preparations with different stabilities; indeed the TLL preparation immobilized at pH 5.0 was the most stable during the thermal inactivation at all pH values. For the hydrolysis of racemic methyl mandelate, the nanobiocatalysts immobilized at pH 5.0 and blocked with ethylenediamine (EDA) and ethanolamine (ETA) obtained good enantioselectivities (68 % and 72 %, respectively) with high catalytic activities in the reaction medium at pH 7.0. The operational stability of the systems was evaluated in the esterification reaction of benzyl alcohol, obtaining up to 61 % conversion after the seventh reaction cycle. These results show that SPMN@PEI-DVS support is a robust strategy for the easy and rapid recovery of the nanobiocatalyst by applying a magnetic field, showing great potential for industrial applications.
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