Behrouz Ghorani

Approaches for the assembly of molecularly imprinted electrospun nanofibre membranes and consequent use in selected target recognition

Molecular recognition plays an indispensable role in nature for the recognition of antibodies, enzymes and nucleic acids. Biomimetic fibrous non-woven materials are being developed to act as highly sensitive and selective artificial receptors based on molecular recognition sites in the constituent fibres. Molecular imprinting technologies (MITs) with specific recognition abilities are currently being developed to produce versatile materials for the recognition of diverse species in various applications, but specifically in membrane separation to express permselectivity. Conventionally, the production of molecularly imprinted polymers (MIPs) involves introducing binding sites where highly cross-linked copolymers are formed around the analyte molecules that act as cavity-creating templates. Subsequent removal of the template molecule provides recognition sites in the polymer that ideally resemble the template in terms of shape, size and functionality. Rebinding of the target molecule within these pre-formed sites can occur when the polymer is incubated in the presence of the template molecule. However, removing of template after polymerization is difficult because cross-linked polymer materials tend to be insoluble. This review paper describes work on new non-covalent molecular imprinting technologies applied to fibrous materials and electrospun fibres that are suitable for selected target recognition. This method has the potential of becoming a tool for producing truly simple, rapid and robust receptors on membranes of the type in regular use in the food industry, making the in-process simultaneous removal of undesirable co-product chemicals and microbial toxins a commercial possibility.

Principles of electrospraying: A new approach in protection of bioactive compounds in foods

ABSTRACT Electrospraying is a potential answer to the demands of nanoparticle fabrication such as scalability, reproducibility, and effective encapsulation in food nanotechnology. Electrospraying (and the related process of electrospinning) both show promise as a novel delivery vehicle for supplementary food compounds since the process can be carried out from an aqueous solution, at room temperature and without coagulation chemistry to produce matrices or particulates in the micro- and nano-range. The presentation of core materials at the nanoscale improves target ability to specific areas of the digestive tract and gives improved control of release rate. Adoption of these electrohydrodynamic atomization technologies will allow the industry to develop a wide range of novel high added value functional foods. To optimize production conditions and maximize throughput, a clear understanding of the mechanism of electrospraying is essential. This article presents a comprehensive review of the principles of electrospraying to produce nanoparticles suitable for food technology application, particularly for use in encapsulation and as nanocarriers.

Controlling the morphology and material characteristics of electrospray generated calcium alginate microhydrogels

Abstract 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, CaCl2 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) CaCl2 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.

Electrospray-assisted drying of live probiotics in acacia gum microparticles matrix

Acacia gum solution was employed as a carrier for electrospray-assisted drying of probiotic cells. To optimize the process, effect of gum concentration, thermal sterilization as a prerequisite for microbial studies, and surfactant addition on physical properties of feed solution was investigated. Increasing gum concentration from 20 to 40 wt.% led to a viscosity increase, whilst surface tension did not change meaningfully and electrical conductivity declined after an increasing trend up to 30 wt.% of the gum. Thermal sterilization increased the viscosity without any significant effect on the conductivity and surface tension. Surfactant addition reduced the surface tension and conductivity but the viscosity increased. Highly uniform particles were formed by electrospray-assisted drying of autoclaved 35 wt.% acacia gum solution containing 1 wt.% Tween 80. Thermal sterilization and surfactant addition improved electrospray-ability of acacia gum solution. Bacterial count showed that more than 96 percent of probiotic cells passed the process viably.

Food-grade gliadin microstructures obtained by electrohydrodynamic processing

This paper presents a comprehensive study on the electrohydrodynamic processing of gliadin to develop food-grade delivery systems with different morphologies. The effects of biopolymer concentration, applied voltage and solution flow-rate on particle morphology, molecular organisation, crystallinity and thermal properties were investigated. Gliadin concentration influenced the apparent viscosity and conductivity of the solutions, giving raise to particle morphologies at 10 wt% gliadin and beaded-free fibers above 25 wt% gliadin. In general, increasing the voltage resulted in smaller average sizes of the obtained structures, while no significant differences in morphology were observed among the tested flow rates. Interestingly, the amide I position in the FTIR reflected changes in protein conformation which could be correlated with the final morphology attained. Moreover, the acetic acid used for solution preparation disrupted the original amino acid chain packing of the gliadin fraction, being the electrospun/electrosprayed samples amorphous. These gliadin-based microparticles and microfibers obtained could serve as food-grade delivery vehicles.