Electrohydrodynamic processing of natural polymers for active food packaging: A comprehensive review

The active packaging materials fabricated using natural polymers is increasing in recent years. Electrohydrodynamic processing has drawn attention in active food packaging due to its potential in fabricating materials with advanced structural and functional properties. These materials have the significant capability in enhancing food's quality, safety, and shelf-life. Through electrospinning and electrospray, fibers and particles are encapsulated with bioactive compounds for active packaging applications. Understanding the principle behind electrohydrodynamics provides fundamentals in modulating the material's physicochemical properties based on the operating parameters. This review provides a deep understanding of electrospray and electrospinning, along with their advantages and recent innovations, from food packaging perspectives. The natural polymers suitable for developing active packaging films and coatings through electrohydrodynamics are intensely focused. The critical properties of the packaging system are discussed with characterization techniques. Furthermore, the limitations and prospects for natural polymers and electrohydrodynamic processing in active packaging are summarized.     

Elastic antibacterial membranes comprising particulate laden fibers for wound healing applications

Medicated skin care products are available in various forms; ranging from lotions and creams to bandages and membranes. In this study, antibacterial particulate laden fibrous membranes (FMs) were prepared via electrospraying of tetracycline hydrochloride-loaded poly(ε-caprolactone) particles alongside electrospinning of thermoplastic polyurethane (TPU) fibers, through which both mechanical and biological aspects of a complete membrane system can be achieved. Random (R) and ordered (P and V) patterns of TPU FMs were afforded using a rotating collector. Water contact angle and bacterial inhibition zone tests were performed to assess suitability of the system specifically for wound care. Stress–strain and in vitro drug release tests were performed to assess suitability of newly developed systems specifically for hybrid membranes (HMs). The highest tensile strength (32.1 ± 4.9 MPa) with elasticity (104.2 ± 6.0%) and the most sustained release rate indicate HMs (P) are potentially suitable materials for wound-care applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47105.     

Biocompatibility and degradability of alginate-poly-L-arginine microcapsules prepared by high-voltage electrostatic process

To explore biocompatibility and degradability of alginate-poly-l-arginine (APLA) microcapsules prepared by high-voltage electrostatic process, this study investigated cytotoxicity, blood compatibility, acute toxicity, and in vivo biocompatibility and degradability of APLA microcapsules. The results showed that the uniform APLA microcapsules almost had no cytotoxicity within 1.0?mg/mL, and their degradation products promoted cell proliferation. APLA microcapsules had excellent hemocompatibility even at 200?mg/mL, and their extract products did not create acute toxicity even at 5,000?mg/kg. The inflammatory responses induced by APLA microcapsules were moderate and decreased with time, and APLA microcapsules could be degraded and phagocytized by tissue cells.     

A Facile Strategy for Preparing PCL/PEG Block Copolymer Microspheres via Electrospraying as Coatings for Cotton Fabrics

Polymeric microspheres can serve as microcarrier matrices and be used to prepare fabric coatings. After embedding spices or drugs in microspheres, and using them to coat fabrics, the coated fabrics can be applied to functional textiles. A facile one‐step, single‐solvent electrospray technology is utilized to produce polycaprolactone (PCL), PCL‐PEG400, and PCL‐PEG1000 microspheres with controlled sizes and tunable surface morphologies by adjusting parameters such as flow rate, voltage, and collection distance. Scanning electron microscopy coupled with an image analysis software (ImageJ) is employed to evaluate the size distribution and structures of the microspheres. Using PCL, PCL‐PEG400, and PCL‐PEG1000 as matrices, spherical particles with micro‐nanostructure surfaces are produced by adjusting the electrospraying parameters. According to observation and analysis results, PCL, PCL‐PEG400, and PCL‐PEG1000 form different microspheres with many porous pits, few pits, or nonporous wrinkles on a spherical surface, respectively. Increasing the flow rate or voltage produces larger or smaller microspheres, respectively. A slight increase in the average particle size is obtained by increasing the collection distance. Cotton fabrics pretreated with adhesive are directly coated by electrospraying to successfully enhance microsphere adhesion on fabric surfaces.     

Pectin‐based films produced by electrospraying

Electrospraying technique was used for the production of pectin films obtaining transparent and flexible products with thicknesses of 23.4 ± 3.04 µm and requiring a lower pectin solution volume (2.67 × 10^?3 mL) than casting (5.97 × 10^?3 mL) to produce films of the same area and thickness; the physical, structural, and thermal characteristics of these films were evaluated. Electrosprayed films were slightly more transparent, and with smoother surface than those obtained by casting, but with more and smaller internal pores, resulting in different film densities (0.7 g/cm³ electrospraying, 1.7 g/cm³ casting), that could be linked to the larger water vapor permeability value obtained. These changes could be related to a physical phenomenon, seeing as the percentage of crystallinity and melting temperature remained invariable for both films. These results show that the electrospraying technique has potential in areas such as wound dressings, tissue engineering, and the release of drugs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43779.     

Water Resistance and Barrier Properties Improvement of Paperboard by Poly(Lactic Acid) Electrospraying

This research attempted to improve water resistance and barrier properties of paperboard by electrospraying the material with poly(lactic acid) (PLA). The focus was to reduce the amount of PLA in the coating process and to achieve the thinnest possible PLA coating layer. PLA solutions were prepared at 0.5%, 1%, 2%, 3% and 4% (w/v) in chloroform. PLA solution (10 ml) was sprayed onto the paperboard. The results showed that water and oil contact angles of paperboard were significantly increased after electrospraying. Water and oil absorption was significantly reduced, especially when using PLA concentration of 1%. PLA concentrations below 1% produced too few PLA particles on the surface for full coverage, whereas concentrations above 1% led to an uneven agglomeration of PLA particles on the substrate. The results also showed that water vapour transmission rate and oxygen transmission rate of paperboard were significantly reduced at PLA concentration of at least 1%. On the basis of electrospraying technique, the amount of PLA can be significantly reduced to achieve results comparable to other common coating methods. Copyright © 2013 John Wiley & Sons, Ltd.     

静电喷射技术制备可酸致突释给药的壳聚糖微颗粒

利用静电喷射技术,以西咪替丁作为模型药物,混有药物的壳聚糖水溶液作为喷射液,甲苯/正己醇的混合溶液作为接收液,成功制备得到可在酸性条件下溶解并突释给药的壳聚糖载药微颗粒。系统考察了交联剂含量对壳聚糖微颗粒的药物包封率以及载药量的影响,并研究了壳聚糖微颗粒在酸性条件下的溶解特性以及在体外的突释给药效果。结果表明,当交联剂质量分数为2%时,壳聚糖微颗粒的包封率及载药量最大,分别为80%和3.8%。由于对苯二甲醛与壳聚糖交联形成的Schiff-base结构,使得壳聚糖微颗粒能够在中性条件下保持结构完整,而在酸性条件下由于Schiff-base结构的不稳定性致使微颗粒迅速溶解。因此,体外释药实验结果显示,在pH = 2、37℃的模拟胃酸溶液中,1min内壳聚糖微颗粒即可达到最大释药效果,而在pH = 6.4、37℃的水溶液中,壳聚糖微颗粒可以较长时间保持稳定,药物释放缓慢。这种具有酸致突释释药性能的壳聚糖微粒载体在胃部给药系统方面有良好的应用前景。     

Electrospray Encapsulation of Hydrophilic and Hydrophobic Drugs in Poly(L‐lactic acid) Nanoparticles

An electrospray method is developed for preparation of beclomethasone‐dipropionate‐ and salbutamol‐sulfate‐loaded biodegradable poly(L ‐lactic acid) nanoparticles. Different set‐up parameters for electrospraying are examined on particle size, and preparation conditions are optimized for producing spherical‐drug‐loaded nanoscale particles by controllable processing parameters. Polylactide (PLA)–drug nanoparticles with average diameters of around 200 nm are achieved in a stable cone‐jet mode with a flow rate of 4 µL min^?1, polymer concentration of 1%, and ammonium hydroxide content of 0.05%. Morphology and size of the drug–polymer nanoparticles are analyzed by scanning electron microscopy and transmission electron microscopy. Changes in the crystallinity of the PLA polymer and the model drugs are detected by X‐ray powder diffraction, and the absence of molecular interactions are confirmed by thermal analyses. The results indicate clearly that electrospraying is a potential method for producing polymeric nanoparticles and for encapsulating both hydrophilic and hydrophobic drugs efficiently into the nanoparticles.