Wyatt Technology Corporation

Liposomes are made of lipid bilayers and are often used in drug delivery by encapsulating the core with therapeutic drugs. During liposome research, formulation, manufacturing and quality control, it is of great importance to monitor liposome size and encapsulation. Field flow fractionation (FFF) with the concomitant use of Multi-Angle Light Scattering (MALS) and Quasi-Elastic Light Scattering (QELS, aka dynamic light scattering) is an ideal tool for such characterization.

There has been a significant resurgence in the development of antibody-drug conjugates (ADC) as target-directed therapeutic agents for cancer treatment. Among the factors critical to effective ADC design is the Drug Antibody Ratio (DAR). The DAR describes the degree of drug addition which directly impacts both potency and potential toxicity of the therapeutic, and can have significant effects on properties such as stability and aggregation. Determination of DAR is, therefore, of critical importance in the development of novel ADC therapeutics and this note shows how multi angle light scattering can help determine the DAR.

Multi angle light scattering (MALS) represents a uniquely powerful technique to determine the absolute molar masses and sizes of proteins in solution. MALS detectors cover a wide detection range of sizes and masses and enable the characterization of protein molecules as monomers, dimers or higher order aggregates.

Low-molecular-weight heparins (LMWHs) are obtained by fractionation or depolymerization of natural heparins. Size-exclusion chromatography (SEC) has been the most common way of measuring the molecular weight but RI or UV detectors alone are relative methods requiring calibration standards. A newer, absolute method involves the use of multi-angle light scattering (MALS), which does not require any standards.

The therapeutic effectiveness of hyaluronic acid (HA) depends critically on its molecular weight: the higher the molecular weight, the longer its benefit. But since there are no standards for HA, multi-angle light scattering as part of SEC-MALS presents the solution to the problem.

Size-exclusion chromatography (SEC) has been the most common way of measuring the molecular weight and molecular weight distributions of LMWHs by using the two most common detection technologies: ultraviolet (UV) coupled with refractive index (RI) detection. However, these detectors embody a relative method in order to determine molecular weights, requiring calibration standards. A newer, absolute method involves the use of multi-angle light scattering (MALS), which does not require any standards.