Controlled Generation of Microspheres Incorporating Extracellular Matrix Fibrils for Three‐Dimensional Cell Culture

A growing body of evidence suggests that studying cell biology in classical two‐dimensional formats, such as cell culture plasticware, results in misleading, non‐physiological findings. This paper describes the optimization of a microsphere‐based system permitting 3D cell culture incorporating physiological extracellular matrix components. Bio‐electrospraying, the most advanced method currently available, is used to produce microspheres containing THP‐1 cells as a model cell line. The bio‐electrospraying para­meters of nozzle size, polymer flow rate, and voltage are systematically investigated in order to allow stable production of size‐controlled microspheres containing extracellular matrix material and human cells. The effect of bio‐electrospraying parameters, alginate type and cell concentration on cell viability are investigated using trypan blue and propidium iodide staining. Bio‐electrospraying has no effect on cell viability nor the ability of cells to proliferate. Cell viability is similarly minimally affected by encapsulation in all types of alginate tested (MVM, MVG, chemical and food‐grade). Cell density of 5 × 106 cells mL^?1 within microspheres is the optimum for cell survival and proliferation. The stable generation of microspheres incorporating cells and extracellular matrix for use in a 3D cell culture will benefit study of many diverse diseases and permit investigation of cellular biology within a 3D matrix.     

A Novel Technique for Forming Self-Assembled Nanotube Structures

A suspension containing multi-wall, hollow structured carbon nanotubes were suspended in polyethylene glycol and electrosprayed. The results present an operational map identifying a parametric window in which stable cone-jet mode exists. At an electric field strength of ∼0.26 kV/mm and corresponding flow rate of ∼1×10^-8 m³s^-1 the finest droplets were generated. These droplets once deposited were analysed using optical and transmission electron microscopy and are compared with those deposits created through a control method. The electrosprayed deposits were further examined using electron diffraction and dispersive X-ray spectroscopy that forms the discussion in this article.     

Robust polymer incorporated TiO2-ZrO2 microsphere coatings by electrospraying technique with excellent and durable self cleaning,antibacterial and photocatalytic functionalities

The applications of self-cleaning coatings on large scale are limited due to their poor durability, remnants of hazardous by-products and lack of biocompatibility. We propose to solve this problem by developing TiO₂-ZrO₂ composite-based self cleaning coatings. In order to achieve this task another important aspect was to select biocompatible polymers poly (methyl methacrylate) and pluronic F-127 (PF-127) as they can enhance the self-cleaning capability of TiO₂-ZrO₂ which itself is biocompatible and endowed with anti-bacterial capability. The selection of a preparation technique that could produce coatings mimicking the nature has also been important and hence Electrospraying technique was selected as the processing method. The samples were then characterized using various techniques like field emission scanning electron microscopy, X-ray diffraction, high resolution transmission electron microscopy, Brunauer–Emmett–Teller analysis, and so forth to fathom the interlink between observed properties and morphology. High quality superhydrophobic and superhydrophilic films have been generated and the surfaces were modulated by the addition of tri-block co-polymer which was found to provide swapping of superhydrophobic nature to superhydrophilic nature. The integration of superhydrophobic, superhydrophilic, photocatalytic and antibacterial properties in the prepared microsphere coatings is a unique achievement and may interest those in the quest for self-cleaning materials for antibacterial coatings in mitigating surgical site infections, medical implants, coronary stent surfaces, and so forth.     

Superhydrophobic and oleophilic micro‐nano hierarchical Pd‐decorated SiO2 layers

This paper reports a novel fluorinated micro‐nano hierarchical Pd‐decorated SiO₂ structure (hereafter called Pd/SiO₂), which was formed by the deposition of Pd nanoparticles (NPs) on SiO₂ microspheres. The SiO₂ layers with microscale roughness were fabricated by electrospraying a solution prepared using the sol‐gel process. Subsequently, the Pd NPs were deposited using an ultraviolet reduction process. The resulting surfaces exhibited a micro‐nano hierarchical morphology. After fluorination, the micro‐nano hierarchical surface exhibited outstanding water repellency with a water contact angle (WCA) of 170° and a sliding angle <5°, indicating excellent superhydrophobic properties. The layers exhibited good long‐term durability and excellent ultraviolet resistance. Interestingly, the surface was oleophilic (CA of oil ~10°). These results show the potential of employing superhydrophobic fluorinated Pd/SiO₂ layers in smart devices, such as self‐cleanable surfaces and intelligent water/oil separation systems.     

Computational study of core‐shell droplet formation in coaxial electrohydrodynamic atomization process

In this study, a computational fluid dynamic (CFD) model was developed to simulate the liquid cone‐jet and core‐shell droplet formation in the Coaxial Electrohydrodynamic Atomization (CEHDA) process. Validation experiments were conducted using poly(lactic acid) (PLA) and poly(lactic‐co‐glycolic acid) (PLGA) solutions as core and shell materials, respectively. Good agreement was obtained between experimental results and simulation predictions in terms of both particle size and core‐shell structure. Investigation of interfacial tension between core and shell fluids showed that a stable compound cone‐jet and droplet can be easily formed using miscible or partially miscible liquids compared with immiscible liquids with higher interfacial tension. It was also found that the nozzle tip configuration has significant effects on droplet production due to differences in fluid motion. The results also showed that the productivity of the CEHDA process, that is, slow production of core‐shell microparticles due to low flow rates, could be enhanced using optimal cone‐shaped nozzle configuration. Overall, this computational model provided a means of designing and optimizing CEHDA processes for large‐scale core‐shell microparticle fabrication in pharmaceutical application, such as selections of materials and nozzle configuration. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4259–4276, 2016     

Recent progress in nano-biotechnology: compartmentalized micro- and nanoparticles via electrohydrodynamic co-jetting

Compartmentalized particles enable co-presentation of dissimilar sets of properties, thereby offering a broad design space for multifunctional particles. Electrohydrodynamic co-jetting is a simple, yet versatile fabrication technique that can be used to prepare such multicompartmental particles and fibers. Processing conditions are summarized for co-jetting of aqueous and organic polymer solutions as well as nanoparticle suspensions. Because particles can comprise distinct polymers in different compartments, selective surface modification becomes possible. The latter can result in unidirectional interactions with cells or may pave new routes towards targeted drug delivery.     

Development of electrosprayed artesunate-loaded core–shell nanoparticles

Objective: Artesunate (ART) is proven to have potential anti-proliferative activities, but its instability and poor aqueous solubility limit its application as an anti-cancer drug. The present study was undertaken to develop coaxial electrospraying as a novel technique for fabricating nanoscale drug delivery systems of ART as the core–shell nanostructures.

Methods: The core–shell nanoparticles (NPs) were fabricated with coaxial electrospraying and the formation mechanisms of NPs were examined. The physical solid state and drug–polymer interactions of NPs were characterized by X-ray powder diffraction (XRPD) and Fourier transform infrared (FTIR) spectroscopy. The effects of materials and electrospraying process on the particle size and surface morphology of NPs were investigated by scanning electron microscopy (SEM). The drug release from NPs was determined in vitro by a dialysis method.

Results: The ART/poly(lactic-co-glycolic) acid (PLGA) chitosan (CS) NPs exhibited the mean particle size of 303?±?93?nm and relatively high entrapment efficiency (80.5%). The release pattern showed an initial rapid release within two hours followed by very slow extended release. The release pattern approached the Korsmeyer–Peppas model.

Conclusions: The present results suggest that the core–shell NPs containing PLGA and CS have a potential as carriers in the anticancer drug therapy of ART.     

静电喷射法制备聚合物微球和微粒

介绍了静电喷射制备微球、微粒的原理、装置及所用聚合物。总结了静电喷射制备微球、微粒的影响因素及所制备微球、微粒的用途。静电喷射制备微球、微粒的影响因素主要包括电压、聚合物溶液流量、聚合物溶液浓度及电导率。已通过静电喷射制备微球、微粒的聚合物有聚己内酯、聚乳酸、聚丙交酯乙交酯、聚膦腈、聚乙烯基吡咯烷酮、壳聚糖等,主要用于药物、蛋白质、酶等生物活性分子的包埋研究。