The Significance of Graphene Oxide-Polyacrylamide Interactions on the Stability and Microstructure of Oil-in-Water Emulsions

Appropriate pretreatment of proteins and addition of xanthan gum (XG) has the potential to improve the stability of oil-in-water (O/W) emulsions. However, the factors that regulate the enhancement and the mechanism are still not clear, which restricts the realization of improving the emulsion stability by directional design of its structure. Therefore, the effects of whey protein micro-gel particles (WPMPs) and WPMPs-XG complexes on the stability of O/W emulsion were investigated in this article to provide theoretical support. WPMPs with different structures were prepared by pretreatment (controlled high-speed shear treatment of heat-set WPC gels) at pH 3.5–8.5. The impact of initial WPC structure and XG addition on Turbiscan Indexes, mean droplet size and the peroxide values of O/W emulsions was investigated. The results indicate that WPMPs and XG can respectively inhibit droplet coalescence and gravitational separation to improve the physical stability of WPC-stabilized O/W emulsions. The pretreatment significantly enhanced the oxidative stability of WPC-stabilized O/W emulsions. The addition of XG did not necessarily enhance the oxidative stability of O/W emulsions. Whether the oxidative stability of the O/W emulsion with XG is increased or decreased depends on the interface structure of the protein-XG complex. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.

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Polymeric Micelles for the Enhanced Deposition of Hydrophobic Drugs into Ocular Tissues, without Plasma Exposure

Pharmaceutics ◽

10.3390/pharmaceutics13050744 ◽

2021 ◽

Vol 13 (5) ◽

pp. 744

Author(s):

Ijeoma F. Uchegbu ◽

Jan Breznikar ◽

Alessandra Zaffalon ◽

Uche Odunze ◽

Andreas G. Schätzlein

Keyword(s):

Polymeric Micelles ◽

Rabbit Model ◽

Penetration Enhancer ◽

Hydrophobic Drugs ◽

Ocular Tissues ◽

Ocular Penetration ◽

Self Assembling ◽

Similar Dose ◽

Oil In Water ◽

The Stability

Commercial topical ocular formulations for hydrophobic actives rely on the use of suspensions or oil in water emulsions and neither of these formulation modalities adequately promote drug penetration into ocular tissues. Using the ocular relevant hydrophobic drug, cyclosporine A (CsA), a non-irritant ocular penetration enhancer is showcased, which may be used for the formulation of hydrophobic actives. The activity of this penetration enhancer is demonstrated in a healthy rabbit model. The Molecular Envelope Technology (MET) polymer (N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan), a self-assembling, micelle-forming polymer, was used to formulate CsA into sterile filtered nanoparticulate eye drop formulations and the stability of the formulation tested. Healthy rabbits were dosed with a single dose of a MET–CsA (NM133) 0.05% formulation and ocular tissues analyzed. Optically clear NM133 formulations were prepared containing between 0.01–0.1% w/v CsA and 0.375–0.75% w/v MET polymer. NM133 0.01%, NM133 0.02% and NM133 0.05% were stable for 28 days when stored at refrigeration temperature (5–6 °C) and room temperature (16–23 °C), but there was evidence of evaporation of the formulation at 40 °C. There was no change in drug content when NM133 0.05% was stored for 387 days at 4 °C. On topical dosing to rabbits, corneal, conjunctival and scleral AUC0–24 levels were 25,780 ng.h g−1, 12,046 ng.h g−1 and 5879 ng.h g−1, respectively, with NM133 0.05%. Meanwhile, a similar dose of Restasis 0.05% yielded lower values of 4726 ng.h/g, 4813 ng.h/g and 1729 ng.h/g for the drug corneal, conjunctival and scleral levels, respectively. NM133 thus delivered up to five times more CsA to the ocular surface tissues when compared to Restasis. The MET polymer was non-irritant up to a concentration of 4% w/v. The MET polymer is a non-irritant ocular penetration enhancer that may be used to deliver hydrophobic drugs in optically clear topical ocular formulations.

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Thermally Stimulated Desorption Optical Fiber-Based Interrogation System: An Analysis of Graphene Oxide Layers’ Stability

Photonics ◽

10.3390/photonics8030070 ◽

2021 ◽

Vol 8 (3) ◽

pp. 70

Author(s):

Maria Raposo ◽

Carlota Xavier ◽

Catarina Monteiro ◽

Susana Silva ◽

Orlando Frazão ◽

...

Keyword(s):

Graphene Oxide ◽

Optical Fiber ◽

Optical Fiber Sensor ◽

Layer By Layer ◽

Film Stability ◽

A Value ◽

Device Reliability ◽

Sensor Devices ◽

Lbl Films ◽

The Stability

Thin graphene oxide (GO) film layers are being widely used as sensing layers in different types of electrical and optical sensor devices. GO layers are particularly popular because of their tuned interface reflectivity. The stability of GO layers is fundamental for sensor device reliability, particularly in complex aqueous environments such as wastewater. In this work, the stability of GO layers in layer-by-layer (LbL) films of polyethyleneimine (PEI) and GO was investigated. The results led to the following conclusions: PEI/GO films grow linearly with the number of bilayers as long as the adsorption time is kept constant; the adsorption kinetics of a GO layer follow the behavior of the adsorption of polyelectrolytes; and the interaction associated with the growth of these films is of the ionic type since the desorption activation energy has a value of 119 ± 17 kJ/mol. Therefore, it is possible to conclude that PEI/GO films are suitable for application in optical fiber sensor devices; most importantly, an optical fiber-based interrogation setup can easily be adapted to investigate in situ desorption via a thermally stimulated process. In addition, it is possible to draw inferences about film stability in solution in a fast, reliable way when compared with the traditional ones.

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Desert beetle-like microstructures bridged by magnetic Fe3O4 grains for enhancing oil-in-water emulsion separation performance and solar-assisted recyclability of graphene oxide

Chemical Engineering Journal ◽

10.1016/j.cej.2021.130904 ◽

2021 ◽

pp. 130904

Author(s):

Yong Xu ◽

Gang Wang ◽

Lijing Zhu ◽

Wanshun Deng ◽

Chunting Wang ◽

...

Keyword(s):

Graphene Oxide ◽

Separation Performance ◽

Water Emulsion ◽

Oil In Water ◽

Emulsion Separation ◽

Desert Beetle ◽

Oil In Water Emulsion ◽

Magnetic Fe3o4

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Preparation of Graphene Oxide/Attapulgite Composites and Their Demulsification Performance for Oil-in-Water Emulsion

Energy & Fuels ◽

10.1021/acs.energyfuels.1c00042 ◽

2021 ◽

Author(s):

Jun Liu ◽

Juan Liu ◽

Jingping Zhong ◽

Jili Shen ◽

Sili Ren

Keyword(s):

Graphene Oxide ◽

Water Emulsion ◽

Oil In Water ◽

Oil In Water Emulsion

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Assessment of Fennel Oil Microfluidized Nanoemulsions Stabilization by Advanced Performance Xanthan Gum

Foods ◽

10.3390/foods10040693 ◽

2021 ◽

Vol 10 (4) ◽

pp. 693

Author(s):

Rubén Llinares ◽

Pablo Ramírez ◽

José Antonio Carmona ◽

Luis Alfonso Trujillo-Cayado ◽

José Muñoz

Keyword(s):

Essential Oil ◽

Rheological Properties ◽

Xanthan Gum ◽

Mechanical Energy ◽

Physical Stability ◽

Processing Condition ◽

Oil In Water ◽

Mechanical Spectra ◽

The Stability ◽

Fennel Oil

In this work, nanoemulsion-based delivery system was developed by encapsulation of fennel essential oil. A response surface methodology was used to study the influence of the processing conditions in order to obtain monomodal nanoemulsions of fennel essential oil using the microchannel homogenization technique. Results showed that it was possible to obtain nanoemulsions with very narrow monomodal distributions that were homogeneous over the whole observation period (three months) when the appropriate mechanical energy was supplied by microfluidization at 14 MPa and 12 passes. Once the optimal processing condition was established, nanoemulsions were formulated with advanced performance xanthan gum, which was used as both viscosity modifier and emulsion stabilizer. As a result, more desirable results with enhanced physical stability and rheological properties were obtained. From the study of mechanical spectra as a function of aging time, the stability of the nanoemulsions weak gels was confirmed. The mechanical spectra as a function of hydrocolloid concentration revealed that the rheological properties are marked by the biopolymer network and could be modulated depending on the amount of added gum. Therefore, this research supports the role of advanced performance xanthan gum as a stabilizer of microfluidized fennel oil-in-water nanoemulsions. In addition, the results of this research could be useful to design and formulate functional oil-in-water nanoemulsions with potential application in the food industry for the delivery of nutraceuticals and antimicrobials.

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