PLGA particle production for water-soluble drug encapsulation: degradation and release behaviour.

Particles for subcutaneous depot use encapsulating a model water-soluble drug have been produced from poly(lactic-glycolic acid) (PLGA) using a membrane emulsification-solvent evaporation technique. The release behaviour, mainly the change in size and inner morphology are reported. During release, the particles initially swelled in size, then reduced.

Pore design and engineering for filters and membranes.

In filtration, the concept of pore size is not easy to define. In microfiltration, there are numerous advantages in employing a surface filtering membrane, rather than one relying on depth filtration mechanisms from a tortuous pore flow channel. Modern manufacturing techniques provide means to produce surface filtering membranes.

Preparation and characterization of PLGA particles for subcutaneous controlled drug release by membrane emulsification.

Uniformly sized microparticles of poly(D,L-lactic-co-glycolic) (PLGA) acid, with controllable median diameters within the size range 40-140 microm, were successfully prepared by membrane emulsification of an oil phase injected into an aqueous phase, followed by solvent removal. Initially, simple particles were produced as an oil in water emulsion, where dichloromethane (DCM) and PLGA were the oil phase and water with stabiliser was the continuous phase. The oil was injected into the aqueous phase through an array type microporous membrane, which has very regular pores equally spaced apart, and two different pore sizes were used: 20 and 40 microm in diameter.

Spreading of liquid drops over saturated porous layers.

Spreading of small liquid drops over thin porous layers saturated with the same liquid is investigated from both theoretical and experimental points of view. A theory is presented that shows that spreading is governed by the same power law as in the case of spreading over a dry solid substrate. The Brinkman's equations are used to model the liquid flow inside the porous substrate.

Spreading of liquid drops over porous substrates.

The spreading of small liquid drops over thin and thick porous layers (dry or saturated with the same liquid) has been investigated in the case of both complete wetting (silicone oils of different viscosities) and partial wetting (aqueous SDS solutions of different concentrations). Nitrocellulose membranes of different porosity and different average pore size have been used as a model of thin porous layers, glass and metal filters have been used as a model of thick porous substrates. The first problem under investigation has been the spreading of small liquid drops over thin porous layers saturated with the same liquid.

Spreading of Surfactant Solutions over Hydrophobic Substrates.

The spreading of surfactant solutions over hydrophobic surfaces is considered from both theoretical and experimental points of view. Water droplets do not wet a virgin solid hydrophobic substrate. It is shown that the transfer of surfactant molecules from the water droplet onto the hydrophobic surface changes the wetting characteristics in front of the drop on the three-phase contact line.