Daniel Some

The macroscopic properties of material based on poly(D,L-lactic-co-glycolic acid) (PLGA) polymers are tunable by molar mass distribution and degree of branching, enabling optimization for applications in the pharmaceutical and medical industries. Size-exclusion chromatography followed by online multi-angle light scattering with intrinsic viscosity detection (SEC–MALS–IV) is an advanced analytical method for determining absolute molar mass distributions, identifying polymer conformation and quantifying branching. SEC–MALS–IV overcomes the errors that can be encountered in molar mass determined by conventional SEC, which arise from chemical composition and molecular structure, and provides comprehensive characterization of PLGA to facilitate the targeted development of optimized polymer.

Colloidal interactions arising from surface-exposed moieties on therapeutic proteins, monoclonal antibodies, antibody–drug conjugates, and other biopharmaceuticals lie at the heart of drug product stability. Therefore, it is not surprising that much effort has been devoted to finding effective means to characterize these interactions and to rapidly screen drug candidates and formulations for optimal colloidal properties. The most common techniques for performing these analyses are based on analytical light scattering, in its two primary flavours: static light scattering (SLS) and dynamic light scattering (DLS). Recent advances in light scattering instrumentation, analytical methods, and algorithms provide developers of biologics with powerful tools to perform these studies.

Ultrahigh-pressure size-exclusion chromatography (UHP-SEC) offers multiple benefits for synthetic polymer characterization. However, despite the many advantages of UHP-SEC, its rapid, low-volume separation is more sensitive to column calibration errors and drift than traditional high performance (HP)-SEC. Additionally, only a small selection of column chemistries are available. It is therefore essential to combine UHP-SEC with online, low-volume multi-angle light scattering instrumentation (UHP-SEC-MALS) to overcome these challenges.

Dynamic light scattering (DLS), widely recognized for its ability to detect aggregation in purified protein solutions, is actually far more versatile and may be applied to the evaluation of stability and viscosity of therapeutic proteins and other biopharmaceuticals. In a fully automated, microwell plate reader format, DLS constitutes a high-throughput biophysical screening technique for early-stage assessment of candidate developability and optimal formulation conditions.

The degree and strength of self-association are critical quality attributes for insulin and its analogues. In this article we present the label-free determination of these quantities using composition-gradient multi-angle light scattering (CG-MALS), enabling the formulation of engineered insulin optimized for stability and efficacy.

Faster analyses, better separations, and lower consumption of sample and mobile phase are the primary drivers of size-exclusion chromatography with sub-2-µm beads and ultrahigh-pressures (UHP-SEC). The flip side of these benefits is higher sensitivity to column calibration errors and drift. There is also a relatively small selection of column chemistries available for eliminating non-ideal sample-column interactions. UHP-SEC can be combined with on-line multi-angle light scattering (UHP-SEC-MALS) to overcome these limitations and provide absolute molar mass and size of biomacromolecules, independently of retention time. UHP-SEC-MALS is also necessary for UHP-SEC characterization of proteins and biotherapeutics that have no appropriate reference standards, such as glycoproteins and PEGylated proteins.

Nanoparticles hold enormous potential for targeted, well-controlled drug delivery. Extensive characterization of nanoscale drug-delivery vehicles is essential to ensure their efficacy and reproducibility. While various methods are available to characterize nanoparticle size, including dynamic light scattering (DLS), electron microscopy, and nanoparticle tracking analysis, field-flow fractionation–multi-angle light scattering (FFF–MALS) is one of the most versatile techniques to determine size, structure, and other properties. This article highlights a study demonstrating the benefits of FFF–MALS–DLS for the characterization of nanolipid particles.

Biopharmaceutical Candidate Screening with Automated Dynamic Light Scattering