Microparticles for cell encapsulation and colonic delivery produced by membrane emulsification

Cell microencapsulation techniques for cancer modelling and drug discovery

Cell encapsulation into spherical microparticles is a promising bioengineering tool in many fields, including 3D cancer modelling and pre-clinical drug discovery. Cancer microencapsulation models can more accurately reflect the complex solid tumour microenvironment than 2D cell culture and therefore would improve drug discovery efforts. However, these microcapsules, typically in the range of 1 - 5000 µm in diameter, must be carefully designed and amenable to high-throughput production. This review therefore aims to outline important considerations in the design of cancer cell microencapsulation models for drug discovery applications and examine current techniques to produce these. Extrusion (dripping) droplet generation and emulsion-based techniques are highlighted and their suitability to high-throughput drug screening in terms of tumour physiology and ease of scale up is evaluated.

Membrane Emulsification as an Emerging Method for Lacticaseibacillus rhamnosus GG® Encapsulation

Techniques capable of producing small-sized probiotic microcapsules with high encapsulation yields are of industrial and scientific interest. In this study, an innovative membrane emulsification system was investigated in the production of microcapsules containing Lacticaseibacillus rhamnosus GG® (Lr), sodium alginate (ALG), and whey protein (WPI), rice protein (RPC), or pea protein (PPC) as encapsulating agents. The microcapsules were characterized by particle size distribution, optical microscopy, encapsulation yield, morphology, water activity, hygroscopicity, thermal properties, Fourier-transform infrared spectroscopy (FTIR), and probiotic survival during in vitro simulation of gastrointestinal conditions. The innovative encapsulation technique resulted in microcapsules with diameters varying between 18 and 29 μm, and encapsulation yields > 93%. Combining alginate and whey, rice, or pea protein improved encapsulation efficiency and thermal properties. The encapsulation provided resistance to gastrointestinal fluids, resulting in high probiotic viability at the end of the intestinal phase (> 7.18 log CFU g-1). The proposed encapsulation technology represents an attractive alternative to developing probiotic microcapsules for future food applications.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11947-023-03099-w.

Complex coacervation assisted by a two-fluid nozzle for microencapsulation of ginger oil: Effect of atomization parameters

This study investigates the influence of the atomization parameters on complex coacervation by atomization, and is following a preceding study that presented the technique and investigated the effects of formulation. Complex coacervated capsules were produced by atomization, using emulsions with 1 and 6%(w/w) of gelatin and ginger oil atomized over a 1%(w/w) solution of gum Arabic, at constant polymer ratio of 1:2 (gelatin:gum Arabic) at pH 3.5. The air velocity at the nozzle varied from 72 to 168 m/s and the emulsion velocity at the nozzle varied from 0.4 to 0.6 m/s, maintaining the air to liquid velocity ratio at 170, 220 and 270. The mean diameter of the microcapsules produced varied from 52 to 75 μm and no crosslinking agents were used. The influence of atomization numbers Weber (We) and Ohnesorge (Oh), shear rate and shear stress on the encapsulation performance was carried out and a proposed model was able to predict the final size of the microcapsules produced at We ≥ 180 and Oh = 0.063. Encapsulation efficiency varied from 9 to 95%, and encapsulation yield varied from 50 to 99%. Finally, optimum conditions based on size prediction and microencapsulation parameters were proposed.

Encapsulation of resveratrol using Maillard conjugates and membrane emulsification

Resveratrol is a stilbene phenolic associated with health-promoting properties such as antioxidant, anti-inflammatory and chemoprevention. Due to its chemical instability and low water solubility, microencapsulation represents a good alternative to provide better results when employing resveratrol as a nutraceutical ingredient. The main purpose of our work was to use low shear membrane emulsification to produce resveratrol-loaded emulsions of low polydispersity and integrate this process to spray drying to produce a powdered product. Resveratrol was dispersed with palm oil in a continuous phase obtained via Maillard reaction. We evaluated the influence of process conditions and phases composition on emulsions properties and performed the characterization of the spray-dried powder. Emulsions droplet size and span decreased as shear stress was increased. Higher dispersed phase fluxes provided increased droplet size polydispersity. Process conditions were set on 60.0 Pa shear stress and 70 L m^-2h^-1 of dispersed phase flux, obtaining emulsions with mean diameter around 30 μm and span of 0.76. Despite this relatively high droplet size of the infeed emulsions, the spray drying process resulted in particles with high encapsulation efficiency (97.97 ± 0.01%), and water content (~3.6%) and diameter (~10.2 μm) similar to particles obtained from fine emulsions in previously reported works.