One of the major challenges with microencapsulation and delivery of low molecular weight bioactive compounds is their diffusional loss during storage and process conditions as well as under gastric conditions. In an attempt to slow down the release rate of core material, electrospray fabricated calcium alginate microhydrogels were coated with low molecular weight and high molecular weight chitosans. Caffeine as a hydrophilic model compound was used due to its several advantages on human behavior especially increasing consciousness. Mathematical modeling of the caffeine release by fitting the data with Korsmeyer-Peppas model showed that Fick's diffusion law could be the prevalent mechanism of the release. Electrostatic interaction between alginate and chitosan (particularly in the presence of 1% low molecular weight chitosan) provided an effective barrier against caffeine release and significantly reduced swelling of particles compared to control samples. The results of this study demonstrated that calcium alginate microhydrogels coated by chitosan could be used for encapsulation of low molecular compounds. However, more complementary research must be done in this field. In addition, electrospray, by producing monodisperse particles, would be as an alternative method for fabrication of microparticles based on natural polymers.
Electrospraying nano- and micro-particle fabrication is a one-step, non-invasive process, which has application in encapsulating of thermosensitive functional, bioactive materials and cells and making microhydrogels. This study investigates the effect of various electrospraying process parameters on the characteristics of calcium alginate microhydrogel particles. The alginate solution concentration, CaCl coagulation bath concentration, voltage, nozzle diameter, distance between nozzle and collecting bath (D), alginate delivery pressure (∼H) were examined. The best droplet formation rate, in non-disperse dripping mode, was obtained at 8 kV using a 500 μm inner diameter nozzle tip, D = 8 cm, H = 20 cm. Morphology, swelling behaviour and texture analysis of the particles which were followed by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) confirmed that 1.5-2% (w/v) CaCl was the desirable concentration for hydrogels formation. Particle size range between 267 and 1500 μm could be obtained by the drip feed mode compared with 2.3-6 μm by the pressure-assisted electrospray through a coaxial head.
Summary
Plantago psyllium L. seed gum (PPSG)/gelatine nanocomposites containing Cuminum cyminum essential oil (CCEO) were prepared via electrospinning, and the antibacterial properties of the electrospun nanofibres were assessed against Staphylococcus aureus. The nanoemulsion was prepared by adding CCEO to the PPSG/gelatine mixture and sonicated. Uniform nanofibres resulted from the nanoemulsion containing 1.5% PPSG, 8% gelatine and 3% CCEO, and no chemical reactions between the components of the electrospun nanofibres were detected. Growth inhibition zone diameter indicated that the electrospun nanofibres containing at least 3% CCEO had the most significant inhibitory effect on the growth of S. aureus. The electrospun PPSG/gelatine‐CCEO nanocomposites are capable of being used as a biodegradable material in food packaging as well as in edible coatings for the preservation of food products.
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