A method is presented to screen food inks for their ability to form 3D structures of sufficient rigidity to be considered dimensionally stable. The storage modulus and damping factor extracted from an amplitude sweep in oscillatory shear measurements of a food ink are used to characterise rigidity. The storage modulus appears in a dimensionless number representing the ratio of deformation force due to food-structure weight to the force countering deformation due to food-ink rigidity. This dimensionless number and the damping factor form the axes of a graph on which a window of dimensional stability is defined assuming a structural-deformation limit of 5% over 1 h. The graph shows that food inks with higher damping factors require higher storage moduli to form dimensionally stable 3D structures. The window allows food inks with appropriate rigidity to be selected or, given food-ink rheology, suitable structural heights to be estimated to form dimensionally stable 3D structures.

The physical strength of the collagen fibre network in the extracellular matrix is due to the covalent crosslinks between the molecules within the fibres (intra-fibrillar crosslinks). Citric acid was investigated as an agent to introduce crosslinks within marine collagen electrospun fibres. We used collagen films to understand the ideal conditions for citric acid crosslinking. This information was used to develop an optimised method for intra-fibrillar crosslinking in electrospun marine collagen fibres, which increased the stability of these fibres in aqueous environments. The optimised method included a spinning solution containing collagen and citric acid at pH3.5 at high concentrations (260:1 citric acid:collagen molar ratio) coupled with high temperature annealing (165°C), which resulted in the highest intra-fibrillar crosslinking density in electrospun fibres.

ActiVLayr is composed of marine collagen nanofibres incorporated with bioactives. This patented technology offers new delivery mechanisms for a wide range of biomaterials for skincare applications. Collagen is solubilized with preferred bioactives in an aqueous based solvent solution to form dry nanofibres via an electrospinning process. During this process the bioactives (depending on the nature of bioactives) are encapsulated or chemically bonded to the nanofibres and attain an even distribution on the matrix. The bioactives remain stable on the matrix during storage of the composition under moisture-free ambient conditions. On exposure to moisture on the skin, the nanofibres dissolve, thereby releasing the bioactives. Incorporating bioactives into the collagen fibre matrix increases the shelf life of the actives while solubility of collagen on the skin assists the successful delivery of actives to the skin. The diverse nature of the ActiVLayr and sonic electrospinning technology provides the potential to carry a wide range of active compounds for many applications such as wound dressings, drug delivery and other healthcare applications.

Plant & Food BioProcessing has developed a process to electrospin denatured whole-chain marine collagen. The collagen is routinely tested on laboratory-scale electrospinning equipment, but when it is electrospun on industrial equipment, the conditions and the product testing criteria differ from those used in the laboratory. A laboratory electrospinning machine was modified to simulate industrial conditions (30 kV). Then, several parameters (voltage, working distance) were adjusted from laboratory- to commercial-scale. These changes did not affect average fiber diameter or deposition rate. The optimum electrospinning conditions were a mixture of laboratory- and commercial-scale conditions (30-50 kV; 10 cm working distance). Reducing the working distance by 5 cm improved the production rate by up to 75%. These changes resulted in better repeatability of electrospun fibers over multiple production runs, with fewer adjustments of solutions and parameters. We recommend this approach to design materials and processes relevant to industrial manufacturing of electrospun fibers. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44836.

It has been proposed that hydrogen bonding plays a role in promoting the electrospinnability of some materials. In this work, the significance of non-covalent interactions in the electrospinnability of aqueous sugar solutions (i.e. mono- and disaccharide) was investigated as a function of carbohydrate concentration. The electrospinnability of concentrated aqueous solutions of glucose, fructose, and sucrose was studied by physicochemical and rheological characterization methods, and by subsequently examining the resulting morphology via scanning electron microscopy. The results on the electrospinning of concentrated saccharide solutions indicated the significance of non-covalent interactions on the electrospinning of these systems. Electro-spinnability models based on critical concentration and visco-elasto capillary theories were compared with the experimental results. It is shown that visco-elasto capillary theory has the closest correlation with the experimental data. The electrospinnability of highly concentrated saccharide solutions appears to be directly related to the density and intermolecular bonding capacity of the solution.

Electrospinning is recognised as an easily implementable method for the production of submicron-diameter polymer fibres. However, electrospinning is problematic for polymers such as biologically derived materials because of their higher viscosity. In this study, a new spinneret design applies shear forces to the polymer solution just prior to electrospinning. The efficacy of shear-electrospinning is proven using concentrated poly(vinyl alcohol) (PVOH) solutions as a model, with solutions designed around the various concentration regimes of PVOH, initially identified via rheological studies. Conventional electrospinning of solutions up to 16.8 wt% PVOH and viscosity in the order of 101 Pa s leads to the formation of ribbon-like fibres. In contrast, shear-electrospinning produces fibres finer in diameter, rounder in cross-section and smoother. Finally, fibre formation from solutions that are non-electrospinnable under conventional electrospinning is shown for the first time to be achievable via shear-electrospinning as demonstrated for a 30 wt% PVOH solution.