Abstract
Background: Dynamic light scattering (DLS) is an important tool to characterize colloidal systems and adequate sizing is particularly critical in the field of protein formulations. Among the different factors that can influence the measurement result, the effect of laser power has so far not been studied thoroughly. Methods: The sensitivity of a DLS instrument was first considered on a theoretical level, followed by experiments using DLS instruments, equipped with two different lasers of (nominal) 45 mW, and 100 mW, respectively. This work analyzes dilute colloidal dispersions of lysozyme as model protein. Results: Theoretical findings agreed with experiments in that only enhanced laser power of 100 mW laser allowed measuring a 0.1 mg/mL protein dispersion in a reliable manner. Results confirmed the usefulness of the presented theoretical considerations in improving a general understanding of the limiting factors in DLS. Conclusions: Laser power is a critical aspect regarding adequate colloidal analysis by DLS. Practical guidance is provided to help scientists specifically with measuring dilute samples to choose both an optimal instrument configuration as well as a robust experimental procedure.
Highlights
Dynamic light scattering (DLS) has become an indispensable technique of size determination for diverse materials: from sub-micron particles to protein formulations [1]
Background: Dynamic light scattering (DLS) is an important tool to characterize colloidal systems and adequate sizing is critical in the field of protein formulations
A substantial number of these biological substances are proteins, which span from comparatively small biopharmaceuticals to rather large therapeutic antibodies [5], and their development comes with specific technical hurdles such as aggregation
Summary
Dynamic light scattering (DLS) has become an indispensable technique of size determination for diverse materials: from sub-micron particles to protein formulations [1]. A substantial number of these biological substances are proteins, which span from comparatively small biopharmaceuticals to rather large therapeutic antibodies [5], and their development comes with specific technical hurdles such as aggregation. Without stabilizers, such as surfactants, proteins tend to agglomerate in solution [6], which is a quality concern as it may affect safety as well as efficacy and represents a significant barrier to product development [7]. Among the different factors that influence DLS analytics of dilute solutions, laser power and its implications on instrument sensitivity has not been studied well. Even though the study focus is on the sizing of protein formulations, our findings are of much wider relevance for any DLS measurement of dilute colloids
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