Vortex Fluidic Mediated Oxidative Sulfitolysis of Oxytocin.

In peptide production, oxidative sulfitolysis can be used to protect the cysteine residues during purification, and the introduction of a negative charge aids solubility. Subsequent controlled reduction aids in ensuring correct disulfide bridging. In vivo, these problems are overcome through interaction with chaperones. Here, a versatile peptide production process has been developed using an angled vortex fluidic device (VFD), which expands the viable pH range of oxidative sulfitolysis from pH 10.5 under batch conditions, to full conversion within 20 min at pH 9-10.5 utilising the VFD. VFD processing gave 10-fold greater conversion than using traditional batch processing, which has potential in many applications of the sulfitolysis reaction.

Vortex fluidic induced mass transfer across immiscible phases.

Mixing immiscible liquids typically requires the use of auxiliary substances including phase transfer catalysts, microgels, surfactants, complex polymers and nano-particles and/or micromixers. Centrifugally separated immiscible liquids of different densities in a 45° tilted rotating tube offer scope for avoiding their use. Micron to submicron size topological flow regimes in the thin films induce high inter-phase mass transfer depending on the nature of the two liquids. A hemispherical base tube creates a Coriolis force as a 'spinning top' (ST) topological fluid flow in the less dense liquid which penetrates the denser layer of liquid, delivering liquid from the upper layer through the lower layer to the surface of the tube with the thickness of the layers determined using neutron imaging. Similarly, double helical (DH) topological flow in the less dense liquid, arising from Faraday wave eddy currents twisted by Coriolis forces, impact through the less dense liquid onto the surface of the tube. The lateral dimensions of these topological flows have been determined using 'molecular drilling' impacting on a thin layer of polysulfone on the surface of the tube and self-assembly of nanoparticles at the interface of the two liquids. At high rotation speeds, DH flow also occurs in the denser layer, with a critical rotational speed reached resulting in rapid phase demixing of preformed emulsions of two immiscible liquids. ST flow is perturbed relative to double helical flow by changing the shape of the base of the tube while maintaining high mass transfer between phases as demonstrated by circumventing the need for phase transfer catalysts. The findings presented here have implications for overcoming mass transfer limitations at interfaces of liquids, and provide new methods for extractions and separation science, and avoiding the formation of emulsions.

Vortex fluidic mediated synthesis of polysulfone.

Polysulfone (PSF) was prepared under high shear in a vortex fluidic device (VFD) operating in confined mode, and its properties compared with that prepared using batch processing. This involved reacting the pre-prepared disodium salt of bisphenol A (BPA) with a 4,4'-dihalodiphenylsulfone under anhydrous conditions. Scanning electron microscopy (SEM) established that in the thin film microfluidic platform, the PSF particles are sheet-like, for short reaction times, and fibrous for long reaction times, in contrast to spherical like particles for the polymer prepared using the conventional batch synthesis. The operating parameters of the VFD (rotational speed of the glass tube, its tilt angle and temperature) were systematically varied for establishing their effect on the molecular weight (M w), glass transition temperature (T g) and decomposition temperature, featuring gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) respectively. The optimal VFD prepared PSF was obtained at 6000 rpm rotational speed, 45° tilt angle and 160 °C, for 1 h of processing with M w ∼10 000 g mol-1, T g ∼158 °C and decomposition temperature ∼530 °C, which is comparable to the conventionally prepared PSF.

Vortex fluidic mediated encapsulation of functional fish oil featuring in situ probed small angle neutron scattering.

Major challenges for optimizing the benefits of fish oil on human health are improved bioavailability while overcoming the strong odor and avoiding significant oxidation of the omega-3 polyunsaturated fatty acids (PUFAs). The scalable continuous flow thin film vortex fluidic device (VFD) improves the Tween 20 encapsulation of fish oil relative to conventional homogenization processing, with the fish oil particles significantly smaller and the content of the valuable omega-3 fatty acids higher. In addition, after 14 days storage the remaining omega-3 fatty acids content was higher, from ca 31.0% for raw fish oil to ca 62.0% of freeze-dried encapsulated fish oil. The VFD mediated encapsulated fish oil was used to enrich the omega-3 fatty acid content of apple juice, as a model water-based food product, without changing its sensory values. The versatility of the VFD was further demonstrated in forming homogenous suspensions of fish oil containing water-insoluble bioactive molecules, curcumin and quercetin. We have also captured, for the first time, real-time structural changes in nanoencapsulation by installing a VFD with in in situ small angle neutron scattering. Real-time measurements afford valuable insights about self-assembly in solution.

Inverted vortex fluidic exfoliation and scrolling of hexagonal-boron nitride.

Exfoliation or scrolling of hexagonal boron nitride (h-BN) occurs in a vortex fluidic device (VFD) operating under continuous flow, with a tilt angle of -45° relative to the horizontal position. This new VFD processing strategy is effective in avoiding the build-up of material that occurs when the device is operated using the conventional tilt angle of +45°, where the h-BN precursor and scrolls are centrifugally held against the wall of the tube. At a tilt angle of -45° the downward flow aided by gravity facilitates material exiting the tube with the exfoliation of h-BN and formation of h-BN scrolls then optimized by systematically varying the other VFD operating parameters, including flow rate and rotational speed, along with concentration of h-BN and the choice of solvent. Water was the most effective solvent, which enhances the green chemistry metrics of the processing.

Vortex fluidic mediated direct transesterification of wet microalgae biomass to biodiesel.

A bottleneck in the production of biodiesel from microalgae is the dewatering and lipid extraction process which is the dominant energy penalty and cost. A novel biodiesel production platform based on vortex fluidic device (VFD)-assisted direct transesterification (DT) of wet microalgal biomass of Chloroparva pannonica was developed and evaluated. Fatty acid extraction and fatty acid to FAME conversion efficiencies were used at different parameter settings to evaluate performance of the processing technology in confined and continuous mode. A response surface method based on Box-Behnken experimental design was used to determine the effects of water content, the ratio of biomass to methanol and residence time in the VFD. Average extraction efficiencies were 41% and conversion efficiencies >90% with the processing technology showing a broad tolerance to parameter settings. The findings suggest that VFD-assisted DT is a simple and effective way to produce biodiesel directly from wet microalgae biomass at room temperature.