Quantifying the effect of particulate impurities on the ice nucleation behavior of pharmaceutical solutions.

Numerous commercially available biopharmaceuticals are frozen or freeze-dried in vials. The temperature at which ice nucleates and its distribution across vials in a batch is critical to the design of freezing and freeze-drying processes. Here we study experimentally how the level of particulate impurities - a key parameter in pharmaceutical manufacturing - affects the ice nucleation behavior.

The Impact of Process Parameters on the Lyophilized Porous Micro-structure: A Case Study of Dextran.

Freeze-drying is used to prolong the shelf life of pharmaceutical formulations stored in vials. To achieve this, formulations are first frozen and then dried, yielding a porous product that can in some cases be stored even at ambient conditions. In this work, the effect of different process parameters on the properties of the porous micro-structure obtained when freeze-drying dextran solutions was studied.

Linear systems characterization of the topographical spatial resolution of optical instruments.

Lateral resolving power is a key performance attribute of Fizeau interferometers, confocal microscopes, interference microscopes, and other instruments measuring surface form and texture. Within a well-defined scope of applicability, limited by surface slope, texture, and continuity, a linear response model provides a starting point for characterizing spatial resolution under ideal conditions. Presently, the instrument transfer function (ITF) is a standardized way to quantify linear response to surface height variations as a function of spatial frequency.

On Solute Recovery and Productivity in Chiral Resolution through Solid-State Deracemization by Temperature Cycling.

Temperature cycling represents an effective means for the deracemization of chiral compounds that crystallize as conglomerates and racemize in solution. In such a process, a suspension enriched in the desired enantiomer is converted into an enantiopure one through periodic cycles of crystal dissolution and crystal growth. We show that performing temperature cycling at higher temperatures leads to faster deracemization and, consequently, higher productivity.

Monitoring Aqueous Sucrose Solutions Using Droplet Microfluidics: Ice Nucleation, Growth, Glass Transition, and Melting.

Freezing and freeze-drying processes are commonly used to extend the shelf life of drug products and to ensure their safety and efficacy upon use. When designing a freezing process, it is beneficial to characterize multiple physicochemical properties of the formulation, such as nucleation rate, crystal growth rate, temperature and concentration of the maximally freeze-concentrated solution, and melting point. Differential scanning calorimetry has predominantly been used in this context but does have practical limitations and is unable to quantify the kinetics of crystal growth and nucleation.