Spray drying of pharmaceuticals and biopharmaceuticals: Critical parameters and experimental process optimization approaches.

Spray drying is increasingly becoming recognized as an efficient drying and formulation technique for pharmaceutical and biopharmaceutical processing. It offers significant economic and processing advantages compared to lyophilisation/freeze-drying techniques even though the optimisation of process parameters is often a costly and time-consuming procedure. Spray Drying has primarily been used in formulating small molecule drugs with low solubility however it is increasingly being applied to the processing of large biomolecules and biopharmaceuticals. This review examines the basics of spray drying process, current technology and various components used in spray drying process. Moreover, it is focused on introducing critical formulation and processing factors in spray drying of small molecule drugs and large biomolecules, their similarities and differences. Finally, it provides an overview of the experimental optimisation strategies designed to achieve optimum spray drying results in the shortest possible timeframe while utilising minimum product.

High-Throughput Generation of Emulsions and Microgels in Parallelized Microfluidic Drop-Makers Prepared by Rapid Prototyping.

We describe the preparation of rapid prototyped parallelized microfluidic drop-maker devices. The manufacturing technique facilitates stacking of the drop-makers vertically on top of each other allowing for a reduced footprint and minimized dead-volume through efficient design of the distribution channels. We showcase the potential of the additive manufacturing technique for microfluidics and the performance of the parallelized device by producing large amounts of microgels with a diameter of ca. 500 µm, a size that is inaccessible using traditional synthetic approaches.

Efficient gas-liquid contact using microfluidic membrane devices with staggered herringbone mixers.

We describe a novel membrane based gas-liquid-contacting device with increased mass transport and reduced pressure loss by combining a membrane with a staggered herringbone static mixer. Herringbone structures are imposed on the microfluidic channel geometry via soft lithography, acting as mixers which introduce secondary flows at the membrane interface. Such flows include Dean vortices and Taylor flows generating effective mixing while improving mass transport and preventing concentration polarization in microfluidic channels. Furthermore, our static herringbone mixer membranes effectively reduce pressure losses leading to devices with enhanced transfer properties for microfluidic gas-liquid contact. We investigate the red blood cell distribution to tailor our devices towards miniaturised extracorporeal membrane oxygenation and improved comfort of patients with lung insufficiencies.

Bioactive gyroid scaffolds formed by sacrificial templating of nanocellulose and nanochitin hydrogels as instructive platforms for biomimetic tissue engineering.

A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geo-metries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering.

Print your own membrane: direct rapid prototyping of polydimethylsiloxane.

Polydimethylsiloxane is a translucent and biologically inert silicone material used in sealants, biomedical implants and microscale lab-on-a-chip devices. Furthermore, in membrane technology, polydimethylsiloxane represents a material for separation barriers as it has high permeabilities for various gases. The facile handling of two component formulations with a silicone base material, a catalyst and a small molecular weight crosslinker makes it widely applicable for soft-lithographic replication of two-dimensional device geometries, such as microfluidic chips or micro-contact stamps. Here, we develop a new technique to directly print polydimethylsiloxane in a rapid prototyping device, circumventing the need for masks or sacrificial mold production. We create a three-dimensional polydimethylsiloxane membrane for gas-liquid-contacting based on a Schwarz-P triple-periodic minimal-surface, which is inaccessible with common machining techniques. Direct 3D-printing of polydimethylsiloxane enables rapid production of novel chip geometries for a manifold of lab-on-a-chip applications.