Fabrication of porous polyimide hollow microspheres through O/W/O multiple emulsion

Effect of hydroxyethyl starch on drug stability and release of semaglutide in PLGA microspheres

The degradation of peptide drugs limits the application of peptide drug microspheres. Structural changes of peptides at the water-oil interface and the destruction of their spatial structure in the complex microenvironment during polymer degradation can affect drug release and in vivo biological activity. This study demonstrates that adding hydroxyethyl starch (HES) to the internal aqueous phase (W1) significantly enhances the stability of semaglutide and optimizes its release behavior in PLGA microspheres. The results showed that this improvement was due to a spontaneous exothermic reaction (ΔH = -132.20 kJ mol-1) facilitated by hydrogen bonds. Incorporating HES into the internal aqueous phase using the water-in-oil-in-water (W1/O/W2) emulsion method yielded PLGA microspheres with a high encapsulation rate of 94.38 %. Moreover, microspheres with HES demonstrated well-controlled drug release over 44 days, unlike the slower and incomplete release in microspheres without HES. The optimized h-MG2 formulation achieved a more complete drug release (83.23 %) and prevented 30.65 % of drug loss compared to the HES-free microspheres within the same period. Additionally, the optimized semaglutide microspheres provided nearly three weeks of glycemic control with adequate safety. In conclusion, adding HES to the internal aqueous phase improved the in-situ drug stability and release behavior of semaglutide-loaded PLGA microspheres, effectively increasing the peptide drug payload in PLGA microspheres.

Macroporous Polyimide Aerogels: A Comparison between Powder Microparticles Synthesized via Wet Gel Grinding and Emulsion Processes

It is noteworthy to mention that synthesizing the polyimide aerogel powder, which is carried out in this study, benefits from two advantages: (i) the powder particles can be used for some specific applications where the monolith is not suitable and (ii) there is a possibility to investigate how a polyimide aerogel monolith can be made through the polyimide powder to reduce its cost and cycle time. In this study, two straightforward methods, wet gel grinding and emulsion, are introduced to prepare polyimide aerogel powders using ambient pressure drying. The microscopic properties of interest, including skeletal and porous structures, microparticle size and assembly, combined with macroscopic properties such as thermal stabilities and conductivities (0.039 W/m·K), confirm that the fabricated microparticles with a size in the range of 7-20 μm and porosity in the range of 65-85% are thermally stable up to 500 °C.

Novel eco-friendly spherical porous adsorbent fabricated from Pickering middle internal phase emulsions for removal of Pb(II) and Cd (II)

Spherical porous materials prepared from the emulsion template used in the water treatment have displayed a vast prospect, as the high surface area, abundant porous structure, convenient operation and excellent adsorption performance. But the tedious fabrication process, high consumption of organic solvent and surfactant limited the application widely. Herein, a facile and eco-friendly spherical porous adsorbent (SPA) is fabricated from the green surfactant-free (corn oil)-in-water Pickering medium internal phase emulsions (Pickering MIPEs) via the convenient ion crosslinking procedure. The Pickering MIPEs synergistically stabilized with the semi-coke (SC), which is the natural particle produced from the shale oil distillation, and sodium alginate (SA) has excellent storage and anti-coalescence stability. The as-prepared porous adsorbent possessed the abundant pore structure, which provided favorable conditions for effective mass transfer in adsorption, and could be tuned by varying the SA dosage. The saturation adsorption capacities of Pb(II) and Cd(II) can be achieved with 460.54 and 278.77 mg/g within 45 min at 25°C, respectively. Overall, this study supplied a viable and eco-friendly route for fabricating the spherical porous adsorbent with a tunable porous structure for heavy metal ion wastewater.

Multi-Encapsulation Combination of O/W/O Emulsions with Polyurea Microcapsules for Controlled Release and Safe Application of Dimethyl Disulfide

Dimethyl disulfide (DMDS), a promising alternative fumigant, has been highly desirable for excellent management of soil pests and diseases. However, high volatility and moderate toxicity of this sulfide limit its application. To address these issues, a novel controlled release formulation of DMDS was proposed employing multiple emulsions and polyurea microcapsules (DMDS@MEs-MCs). The successful combination of the two technologies was revealed by confocal laser scanning microscopy, scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared. According to the multiple encapsulation structure, the encapsulation efficiency decreased by only 3.13% after thermal storage, compared with a 15.21% decrease of microcapsules made with only a monolayer film. DMDS@MEs-MCs could effectively control the release of active ingredient, which increased applicator and environmental safety during application. Moreover, it could be facilely used by spraying and drip irrigation instead of a special fumigation device. The innovative formulation exhibited better control efficacy on soil pathogens (Fusarium spp. and Phytophthora spp.) and root-knot nematodes (Meloidogyne spp.) than DMDS technical concentration (DMDS TC). In addition, it did not inhibit seed germination after 10 days when the plastic film was removed from the fumigated soil. This method appears to be of broad interest for the development of safe and handy fumigant application.

Facile Fabrication of Polyimide-alumina Composite Coatings by Liquid Flame Spray

Polyimide is type of heterocyclic polymer compound characterized by an imide ring structure. The aromatic ring structure in polyimide facilitates good electrical properties, mechanical properties, thermal properties and radiation resistance, etc. It is widely used in the aerospace field, in electronic components and in the semiconductor industry. Traditional methods for the preparation of polyimide films have different limitations. Here, a new one-step method was established to prepare polyimide coatings using liquid flame spray. The effect of different mass fraction on the surface and cross section structure characteristics of polyimide coatings was studied. The formation process of the polyimide-alumina composite coatings was analyzed using single particles and coatings with different amount of alumina. The composite coating shows a flat and dense structure and excellent dielectric properties. The results shed light on construction of polymer-inorganic composite layers for widespread applications.