External surface area determination of lipid vesicles using trinitrobenzene sulfonate and ultraviolet/visible spectrophotometry.

The lamellarity of liposomes is an important parameter to be controlled in liposomal delivery-release applications. A practical estimate of the degree of liposome lamellarity can be obtained by measuring the relative external surface area of the liposomes using a chemical assay. All such assays are based on a signal change caused by exposed marker lipids on reaction with a specific externally added reagent.

Formation of multilayered biopolymer microcapsules and microparticles in a multiphase microfluidic flow.

This paper reports the development of a scalable continuous microfluidic-based method for the preparation of multilayered biopolymer microcapsules and microparticles, with a size range of 1 to 100 μm, in a single-layered polydimethylsiloxane-based device. This new approach has been utilised to produce polyethylene oxide (PEO)-based microparticles, layered with subsequent stage wise coatings of polylactide-based block copolymers and polyvinylpyrrolidone. The production process was shown to allow for on-chip encapsulation of protein and vitamin molecules in the biopolymer micro particles, without any further handling after collection from the device.

A synthetic elastomer based on acrylated polypropylene glycol triol with tunable modulus for tissue engineering applications.

As strategies for manipulating cellular behaviour in vitro and in vivo become more sophisticated, synthetic biomaterial substrates capable of reproducing critical biochemical and biophysical properties (or cues) of tissue micro-environments will be required. Cytoskeletal tension has been shown to be highly deterministic of cell fate decisions, yet few synthetic biomaterials are capable of modulating cytoskeletal tension of adhered cells through variations in stiffness, at least in the ranges applicable to tissue properties (e.g.

A microfluidic-based method for the transfer of biopolymer particles from an oil phase to an aqueous phase.

Biopolymer microgels produced in microfluidic devices via the formation of a water-in-oil emulsion are usually collected at the outlet of the device and thoroughly washed from the oil phase in an additional, lengthy processing step. This paper reports a microfluidic-based method which allows for continuous on-chip manufacture of aqueous-based biopolymer microparticles in an oily continuous phase and thereafter the transfer of these particles from the oily carrier phase to a second aqueous continuous phase. This was achieved by surface patterning the PDMS channel walls using UV polymerization of poly(acrylic acid) (PAA) in order to obtain a hybrid device with distinct hydrophilic and hydrophobic sections.

Biopolymer microparticle and nanoparticle formation within a microfluidic device.

This paper reports a novel microfluidic method for the production of cross-linked alginate microparticles and nanoparticles. We describe a continuous process relying on both thermodynamic and hydrodynamic factors to form microdroplets. A rapid cross-linking reaction thereafter allows solidification of the polymer droplets either within the microfluidic device or "off-chip" to form alginate micro- and nanoparticles.