RESUMO

Plant-based insecticides offer advantages such as negligible residual effects, reduced risks to both humans and the environment, and immunity to resistance issues that plague conventional chemicals. However, the practical use of monoterpenes in insect control has been hampered by challenges including their poor solubility and stability in aqueous environments. In recent years, the application of nanotechnology-based formulations, specifically nanoemulsions, has emerged as a prospective strategy to surmount these obstacles. In this study, we developed and characterized nanoemulsions based on cymene and myrcene and assessed their toxicity both in vitro using human keratinocytes (HaCAT) cells and in an in vivo model involving Galleria mellonella larvae. Additionally, we investigated the insecticidal efficacy of monoterpenes against the mosquito Aedes aegypti, the primary dengue vector, via larval bioassay. Employing a low-energy approach, we successfully generated nanoemulsions. The cymene-based nanoemulsion exhibited a hydrodynamic diameter of approximately 98 nm and a zeta potential of -25 mV. The myrcene-based nanoemulsion displayed a hydrodynamic diameter of 118 nm and a zeta potential of -20 mV. Notably, both nanoemulsions demonstrated stability over 60 days, accompanied by controlled release properties and low toxicity towards HaCAT cells and Galleria mellonella larvae. Moreover, the nanoemulsions exhibited significant lethality against third-instar Aedes aegypti larvae at a concentration of 50 mg/L. In conclusion, the utilization of nanoemulsions encapsulating cymene and myrcene presents a promising avenue for overcoming the limitations associated with poor solubility and stability of monoterpenes. This study sheds light on the potential of the nanoemulsions as effective and environmentally friendly insecticides in the ongoing battle against mosquito-borne diseases.

RESUMO

Microalgae peptides have many medical and industrial applications due to their functional properties. However, the rapid degradation of peptides not naturally present in biological samples represents a challenge. A strategy to increase microalgae peptide stability in biological samples is to use carriers to protect the active peptide and regulate its release. This study explores the use of gold nanoparticles (AuNPs) as carriers of the Chlorella microalgae peptide (VECYGPNRPQF). The potential of these peptide biomolecules as stabilizing agents to improve the colloidal stability of AuNPs in physiological environments is also discussed. Spectroscopic (UV-VIS, DLS) and Microscopic (TEM) analyses confirmed that the employed modification method produced spherical AuNPs by an average 15 nm diameter. Successful peptide capping of AuNPs was confirmed with TEM images and FTIR spectroscopy. The stability of the microalgae peptide increased when immobilized into the AuNPs surface, as confirmed by the observed thermal shifts in DSC and high zeta-potential values in the colloidal solution. By optimizing the synthesis of AuNPs and tracking the conferred chemical properties as AuNPs were modified with the peptide via various alternative methods, the synthesis of an effective peptide-based coating system for AuNPs and drug carriers was achieved. The microalgae peptide AuNPs showed lower ecotoxicity and better viability than the regular AuNPs.

RESUMO

The present study aims to describe colloidal and acid gelling properties of mixed suspensions of pea and milk proteins. Mixed protein suspensions were prepared by adding pea protein isolate to rehydrated skimmed milk (3% w/w protein) to generate four mixed samples at 5, 7, 9, and 11% w/w total protein. Skimmed milk powder was also used to prepare four pure milk samples at the same protein concentrations. The samples were analyzed in regard to their pH, viscosity, color, percentage of sedimentable material, heat and ethanol stabilities, and acid gelling properties. Mixed suspensions were darker and presented higher pH, viscosity, and percentage of sedimentable material than milk samples. Heat and ethanol stabilities were similar for both systems and were reduced as a function of total protein concentration. Small oscillation rheology and induced syneresis data showed that the presence of pea proteins accelerated acid gel formation but weakened the final structure of the gels. In this context, the results found in the present work contributed to a better understanding of mixed dairy/plant protein functionalities and the development of new food products.

RESUMO

A ferrofluid with 1,2-Benzenediol-coated iron oxide nanoparticles was synthesized and physicochemically analyzed. This colloidal system was prepared following the typical co-precipitation method, and superparamagnetic nanoparticles of 13.5 nm average diameter, 34 emu/g of magnetic saturation, and 285 K of blocking temperature were obtained. Additionally, the zeta potential showed a suitable colloidal stability for cancer therapy assays and the magneto-calorimetric trails determined a high power absorption density. In addition, the oxidative capability of the ferrofluid was corroborated by performing the Fenton reaction with methylene blue (MB) dissolved in water, where the ferrofluid was suitable for producing reactive oxygen species (ROS), and surprisingly a strong degradation of MB was also observed when it was combined with H2O2. The intracellular ROS production was qualitatively corroborated using the HT-29 human cell line, by detecting the fluorescent rise induced in 2,7-dichlorofluorescein diacetate. In other experiments, cell metabolic activity was measured, and no toxicity was observed, even with concentrations of up to 4 mg/mL of magnetic nanoparticles (MNPs). When the cells were treated with magnetic hyperthermia, 80% of cells were dead at 43 °C using 3 mg/mL of MNPs and applying a magnetic field of 530 kHz with 20 kA/m amplitude.

Assuntos

Coloides/química , Coloides/farmacologia , Hipertermia Induzida/métodos , Nanopartículas Magnéticas de Óxido de Ferro/química , Espécies Reativas de Oxigênio/metabolismo , Catecóis/química , Linhagem Celular , Coloides/síntese química , Citotoxinas/síntese química , Citotoxinas/química , Citotoxinas/farmacologia , Humanos , Concentração de Íons de Hidrogênio , Magnetismo , Microscopia Eletrônica de Transmissão , Oxidantes/síntese química , Oxidantes/química , Oxidantes/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Difração de Raios X

RESUMO

The present work addresses some fundamental aspects in the preparation of protein-conjugated gold nanoparticles, in order to ensure an appropriate final product. Ten broadly available and/or easy to implement analytical tools were benchmarked and compared in their capacity to provide reliable and conclusive information for each step of the procedure. These techniques included transmission electron microscopy, UV/VIS spectroscopy, dynamic light scattering, zeta-potential, Fourier-transformed infrared spectroscopy, colloidal stability titration, end-point colloidal stability analysis, cyclic voltammetry, agarose gel electrophoresis and size-exclusion chromatography (SEC). Four different proteins widely used as adaptors or blocking agents were tested, together with 13 nm gold nanoparticles containing different surface chemistries. Among all tested techniques, some of the least popular among nanomaterial scientists probed to be the most informative, including colloidal stability, gel electrophoresis and SEC; the latter being also an efficient purification procedure. These three techniques provide low-cost, low time consuming, sensitive and robust ways to assess the success of the nanoparticle bioconjugation steps, especially when used in adequate combinations.

Assuntos

Nanopartículas , Coroa de Proteína , Medicina de Precisão

RESUMO

Aim: This work is focused on obtaining degradable mesoporous silica nanoparticles (DMSNs) which are able to maintain their colloidal stability in complex biological media. Materials & methods: DMSNs were synthesized using different ratios of disulfide organosilane (degradable structural moiety) and further functionalized with sulfobetaine silane (SBS) to enhance colloidal stability and improve biological compatibility. Results: There was a clear trade-off between nanoparticle degradability and colloidal stability, since full optimization of the degradation process generated unstable particles, while enhancing colloidal stability resulted in poor DMSNs degradation. It was also shown that acidic pH improved particle degradation which is commonly triggered by reduction stimulus. Conclusion: A chemical composition window was found where DMSNs presented satisfactory colloidal stability in biologically relevant medium, meaningful degradation profiles and high biocompatibility.

Assuntos

Nanopartículas , Dióxido de Silício , Silanos

RESUMO

Aim: To develop a series of superparamagnetic iron oxide nanoparticles (SPIONs) by coconjugating them with ibuprofen (ibu) and glycerol phosphate (glycerol) or ibu and glucose-1-phosphate and to assess capacity of these conjugates to inhibit the release of nitric oxide (NO) in macrophages, even at low concentrations. Materials & methods: The SPION conjugates were characterized and their properties evaluated showing the influence of those ligands on colloidal stability and inhibition of NO-release demonstrated. The cytotoxicity and possible anti-inflammatory activity were evaluated using murine macrophages (RAW 247.6). Results: SPION-glycerol phosphate/ibu conjugates inhibited the NO production induced by lipopolysaccharides, indicating a potential anti-inflammatory activity. Conclusion: SPION conjugated with ibu was shown to inhibit NO-release even at very low concentrations, suggesting possible action against inflammatory diseases.

Assuntos

Nanopartículas Magnéticas de Óxido de Ferro , Animais , Ibuprofeno/farmacologia , Lipopolissacarídeos , Camundongos , Óxido Nítrico , Células RAW 264.7

RESUMO

Chitosan has received a lot of attention as a carrier for small interfering RNA (siRNA), due to its capacity for complexation and intracellular release of these molecules. However, one of its limitations is its insolubility at neutral pH and the tendency towards aggregation of its nanoparticles in isotonic ionic strength. In this study, a series of amphipathic chitosans were synthesized by varying the degree of acetylation (DA) from ˜2 to ˜30 mol% and the degree of substitution (DS) from 5 to 25%. by tertiary amino groups (DEAE) The results showed that the adjustment of these parameters decreases the interparticle interactions mediated by hydrogen bonding to obtain nanoparticles with improved colloidal stability. siRNA-containing nanoparticles of 100 to 150 nm with low polydispersities (0.15-0.2) and slightly positive zeta potentials (˜+ 5 mV) were resistant to aggregation at pH 7.4 and ionic strength of 150 mM. This resistance to aggregation is provided by changes on the nanoparticle surface and highlights the importance of more organized self-assembly in providing colloidal stability at physiological conditions. Additionally, the PEGylation of the most promising vectors conferred favorable physicochemical properties to nanoparticles. The chitosans and their nanoparticles exhibited low toxicity and an efficient cell uptake, as probed by confocal microscopy of rhodamine labeled vectors. The results provide a new approach to overcome the limited stability of chitosan nanoparticles at physiological conditions and show the potential of these amphipathic chitosans as siRNA carriers.

Assuntos

Quitosana/análogos & derivados , Portadores de Fármacos/química , Nanopartículas/química , RNA Interferente Pequeno/administração & dosagem , Tensoativos/química , Anidridos Acéticos/química , Acetilação , Animais , Quitosana/síntese química , Quitosana/metabolismo , Quitosana/toxicidade , Dietilaminas/química , Portadores de Fármacos/síntese química , Portadores de Fármacos/metabolismo , Portadores de Fármacos/toxicidade , Fluorescência , Corantes Fluorescentes/química , Concentração de Íons de Hidrogênio , Camundongos , Nanopartículas/metabolismo , Nanopartículas/toxicidade , Tamanho da Partícula , Polietilenoglicóis/síntese química , Polietilenoglicóis/química , Polietilenoglicóis/metabolismo , Polietilenoglicóis/toxicidade , Células RAW 264.7 , RNA Interferente Pequeno/química , Rodaminas/química , Tensoativos/síntese química , Tensoativos/metabolismo , Tensoativos/toxicidade

RESUMO

The widespread production and application of carbon nanotubes (CNT) have raising concerns about their release into the environment and, the joint toxicity of CNT with pre-existing contaminants needs to be assessed. This is the first study that investigated the co-exposure of oxidized multiwalled carbon nanotubes (ox-MWCNT) and cadmium (Cd) using a zebrafish liver cell line (ZFL). Two in vitro co-exposure protocols differing by the order of ox-MWCNT interaction with Cd and fetal bovine serum (FBS) proteins were evaluated. Ox-MWCNT was physical and chemical characterized and its adsorption capacity and colloidal stability in cell culture medium was determined in both protocols. Cytotoxicity was investigated by MTT, neutral red, trypan blue, lactate dehydrogenase assays and the necrosis and apoptosis events were determined using flow cytometer. The Cd presence in medium did not interfere in the protein corona composition of MWCNT but the order of interaction of FBS and Cd interfered in its colloidal stability and metal adsorption rate. The ox-MWCNT increased Cd toxicity at low concentration probably by a "Trojan horse" and/or synergistic effect, and induced apoptosis and necrosis in ZFL cells. Although it was not observed differences of toxicity between protocols, the interaction of ox-MWCNT first with Cd led to its precipitation in cell culture medium and, as a consequence, to a possible false viability result by neutral red assay. Taken together, it was evident that the order of compounds interactions disturbs the colloidal stability and affects the in vitro toxicological assays. Considering that Protocol A showed more ox-MWCNT stability after interaction with Cd, this protocol is recommended to be adopted in future studies.

Assuntos

Cádmio/toxicidade , Nanotubos de Carbono/toxicidade , Testes de Toxicidade , Peixe-Zebra/metabolismo , Adsorção , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Citometria de Fluxo , Nanotubos de Carbono/ultraestrutura , Necrose , Oxirredução , Tamanho da Partícula , Eletricidade Estática , Termogravimetria , Poluentes Químicos da Água/toxicidade

RESUMO

Zein, a protein extracted from maize, can be employed to easily produce nanoscale particles suitable for use as carrier systems. This review investigates the main methods for obtaining zein nanoparticles, as well as the problems and options available in the development of stable colloidal suspensions. Considerable gaps were identified in the literature concerning this topic, with studies being unclear about the factors that affect the stability of zein particles. In the vast majority of cases, no data are presented in relation to the stability of the formulations over time. It could be concluded that in order to produce a high quality system, detailed evaluation is required, considering factors including the zein concentration, pH, ionic strength, thermal treatment of the protein prior to preparation of the nanoparticles, strategies employing other materials as coatings, and the storage conditions. It is extremely important that these aspects should be considered during product development, prior to commercial-scale manufacture.

RESUMO

AIM: To study freeze-drying of silica nanoparticles (SiO2NPs) in order to find suitable conditions to produce lyophilized powders with no aggregation after resuspension and storage. METHODS: SiO2NPs were synthesized using a Stöber-based procedure, and characterized by scanning electron microscopy, dynamic light scattering and nitrogen adsorption/desorption isotherms. SiO2NPs hydrodynamic diameters were compared prior and after freeze-drying in the presence/absence of carbohydrate protectants. RESULTS: Glucose was found to be the most suitable protectant against the detrimental effects of lyophilization. The minimum concentration of carbohydrate required to effectively protect SiO2NPs from aggregation during freeze-drying is influenced by the nanoparticle's size and texture. Negligible aggregation was observed during storage. CONCLUSION: Carbohydrates can be used during SiO2NPs freeze-drying process to obtain redispersable solids that maintain original sizes without residual aggregation.

Assuntos

Carboidratos/química , Liofilização/métodos , Nanopartículas/química , Dióxido de Silício/química , Composição de Medicamentos , Estabilidade de Medicamentos , Difusão Dinâmica da Luz , Humanos , Nanomedicina , Tamanho da Partícula , Pós , Solubilidade , Propriedades de Superfície

RESUMO

HYPOTHESIS: The low Ksp value of Fe(OH)3 (3 × 10-38 at 298 K) explain the immediate coagulation when the pH of a solution of Fe(III) is adjusted to 7. However, stable dispersions of Fe(OH)3 can be formed when the pH is adjusted to 7 in the presence of wormlike micelles formed by cetyltrimethylammonium bromide and sodium salicylate. The formation of a structure containing Fe(OH)3 nanoparticles decorating wormlike micelles is responsible for the high stability of the dispersions. EXPERIMENTS: Fe(OH)3 nanoparticles were obtained by increasing the pH of solutions of cetyltrimethylammonium bromide and Fe(III), previously complexed with salicylate at pH 3. The interaction between nanoparticles and the chains of wormlike micelles was investigated by DLS, SAXS, TEM and Cryo-TEM. FINDINGS: DLS revealed higher scattering contrast and slower diffusion for wormlike micelles in the presence of nanoparticles. These results were interpreted as the decoration of the chains of wormlike micelles by nanoparticles of Fe(OH)3. A pearl-necklace model was successfully used to adjust SAXS curves, revealing nanoparticles with ∼3 nm of diameter, spaced ∼2 nm apart along the string. This result agrees with TEM and Cryo-TEM images. The formed structure prevents the coagulation of nanoparticles, assuring high stability to the dispersion.

Assuntos

Antibacterianos/química , Descoberta de Drogas , Farmacorresistência Bacteriana , Nanopartículas/química , Antibacterianos/administração & dosagem , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/epidemiologia , Humanos , Nanopartículas/administração & dosagem

RESUMO

The optimization of bilayer coverage on particles is important for a variety of biomedical applications, such as drug, vaccine, and genetic material delivery. This work aims at optimizing the deposition of cationic bilayers on silica over a range of experimental conditions for the intervening medium and two different assemblies for the cationic lipid, namely, lipid films or pre-formed lipid bilayer fragments. The lipid adsorption on silica in situ over a range of added lipid concentrations was determined from elemental analysis of carbon, hydrogen, and nitrogen and related to the colloidal stability, sizing, zeta potential, and polydispersity of the silica/lipid nanoparticles. Superior bilayer deposition took place from lipid films, whereas adsorption from pre-formed bilayer fragments yielded limiting adsorption below the levels expected for bilayer adsorption.

RESUMO

Silver-coated orthopedic implants and silver composite materials have been proposed to produce local biocidal activity at low dose to reduce post-surgery infection that remains one of the major contributions to the patient morbidity. This work presents the synthesis combined with the characterization, colloidal stability in biological relevant media, antimicrobial activity and handling properties of silver nanoparticles (Ag-NP) before and after freeze dry and storage. The nanomaterial was synthesized in aqueous solution with simple, reproducible and low-cost strategies using bovine serum albumin (BSA) as the stabilizing agent. Ag-NP were characterized by means of the size distribution and morphology (UV-vis spectra, dynamic light scattering measurements and TEM images), charge as a function of the pH (zeta potential measurements) and colloidal stability in biological relevant media (UV-vis spectra and dynamic light scattering measurements). Further, the interactions between the protein and Ag-NP were evaluated by surface enhanced Raman spectroscopy (SERS) and the antimicrobial activity was tested with two bacteria strains (namely Staphylococcus aureus and Staphylococcus epidermidis) mainly present in the infections caused by implants and prosthesis in orthopedic surgery. Finally, the Ag-NP dispersed in aqueous solution were dried and stored as long-lasting powders that were easily reconstituted without losing their stability and antimicrobial properties. The proposed methods to stabilize Ag-NP not only produce stable dispersions in media of biological relevance but also long-lasting powders with optimal antimicrobial activity in the nanomolar range. This level is much lower than the cytotoxicity determined in vitro on osteoblasts, osteoclasts and osteoarthritic chondrocytes. The synthesized Ag-NP can be incorporated as additive of biomaterials or pharmaceutical products to confer antimicrobial activity in a powdered form in different formulations, dispersed in aqueous and non-aqueous solutions or coated on the surface of different materials.

Assuntos

Antibacterianos/química , Nanopartículas Metálicas/química , Soroalbumina Bovina/química , Prata/química , Antibacterianos/farmacologia , Meios de Cultura

RESUMO

El objetivo de este trabajo fue comprobar la optimización de la encapsulación de avobenzona en liposomas, y evaluar si constituye una barrera física de protección contra la fotodegradación de avobenzona en presencia de octilmetoxicinnamato. Se aplicó un diseño experimental para optimizar los procesos de encapsulación. Los resultados obtenidos mostraron un aumento significativo en la eficiencia de encapsulación al encontrar una relación óptima del agente encapsulante con el agente a encapsular y las interacciones apropiadas entre los factores evaluados. Los valores obtenidos en la eficiencia de encapsulación están alrededor de un 90,00 por ciento y el tamaño logrado fue de 9,156 mm. La fotoestabilidad de la avobenzona en presencia del filtro solar UVB, octilmetoxicinnamato, mejoró al estar encapsulado en liposomas con un porcentaje de degradación del 22,07 por ciento contra un 32,96 por ciento de la avobenzona sin encapsular, y la estabilización coloidal de la dispersión de liposomas mejoró con la utilización de carbopol 940 al 1,00 por ciento. En conclusión, la encapsulación de avobenzona en liposomas al usar isolecitina se logra con alta eficiencia, y se comproba que la degradación de la avobenzona promovida por la luz disminuye al estar encapsulada, aun en presencia de octilmetoxicinnamato.

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This study was aimed at confirming the optimization of Avobenzone encapsulation in liposomes, and at evaluating whether this is a physical barrier to protect AVO from photodegradation in presence of octylmetoxycinnamate or not. An experimental design served to optimize the processes of encapsulation. The results showed a significant increase in the encapsulation efficiency since optimal relationship between the encapsulating agent and the agent to be encapsulated, as well as adequate interactions among the studied factors were found. The values of encapsulation efficiency were roughly 90.00 percent and the particle size obtained was 9.156 mm. The Avobenzone photostability in presence of UVB filter octylmetoxycinnamate improved when being encapsulated in liposomes, with a degradation percentage of 22.07 percent against 32.96 percent of the non-encapsulated, and the colloidal stabilization of liposomal dispersion improved with the use of 1.00 percent Carbopol 940. It can be concluded that the encapsulation of avobenzone in liposomes using isolecitine is highly efficient, and it is confirmed that Avobenzone photodegradation decreases when it is encapsulated, regardless of octylmetoxycinnamate.