0

Beyond a Simple Snapshot: Why Kinetic DLS is Crucial for Nanomedicine Development

In the fast-moving field of nanomedicine, nature-inspired platforms like ferritin are revolutionizing drug delivery. These self-assembling protein cages offer a biocompatible and biodegradable way to encapsulate therapeutic payloads. However, harnessing their potential depends on a delicate process: triggering them to open for drug loading and then reassemble to trap the cargo, all without causing irreversible damage or aggregation.

While many labs can analyze the final product, they often lack a clear understanding of the assembly and disassembly process itself. This can lead to inefficient loading, inconsistent batches, and unpredictable outcomes, as subtle changes in conditions can have dramatic effects.

To truly optimize these advanced nanocarriers, developers need a real-time, dynamic view of the process as it happens. A pivotal study on ferritin behavior shows that the key to this insight lies in using a powerful analytical technique to track the kinetics of the reaction: Dynamic Light Scattering (DLS).

A Technique for a Dynamic Process

Understanding the unique strength of DLS in this application reveals why it is so indispensable.

Dynamic Light Scattering (DLS) is the industry standard for measuring the hydrodynamic size of nanoparticles in a suspension. While it is excellent for a final quality check, its true power in process development comes from its ability to perform time-resolved measurements. It can answer not just “What is the size?” but “How and how fast is the size changing?” This provides a direct window into processes like:

• Disassembly: Watching a 12 nm ferritin cage break down into smaller subunits.

• Aggregation: Detecting the rapid formation of unwanted, micron-sized clumps.

• Reassembly: Monitoring the return of the protein to its original, functional size.

A single, static measurement can be misleading. A kinetic analysis, however, tells the full story of the formulation process.

Real-Time Monitoring in Practice

A 2022 study in Applied Materials Today perfectly demonstrated the power of this kinetic approach. Researchers set out to understand how four different types of ferritin (FRT) nanocages—from equine, human, and even archaeal sources—disassembled in response to rapid pH changes.

To capture these fast-acting kinetics, the researchers needed an instrument capable of rapid, continuous measurement directly within the sample. For this critical task, they used the Vasco Kin™️ Particle Size Analyzer. By adding an acid or base directly to the sample cuvette, they could monitor the particle size distribution every few seconds over a 15-minute period.

The results were revealing. The Vasco Kin showed that each ferritin behaved uniquely:

• Equine L/H-ferritin (EcaLH) disassembled proportionally and predictably.

• Equine L-ferritin (EcaL), under mildly acidic conditions, immediately formed massive aggregates >1,000 nm in size—a disastrous outcome for drug delivery.

• Human H-ferritin (HsaH) broke down not into individual subunits, but into stable subunit clusters.

• Archaeal ferritin (Pfu) was remarkably stable, disassembling very slowly.

This kinetic data provided an unprecedented level of real-time feedback, enabling the researchers to identify the optimal pH conditions for each specific ferritin type and, critically, which conditions to avoid.

The Challenge of Kinetic Measurement

This advanced level of process understanding requires specialized equipment. You cannot capture rapid disassembly or aggregation by taking a sample, walking it to another room, and running a 3-minute analysis. The reaction will be over before you even begin.

The solution is to bring the measurement directly to the sample. An in situ DLS system with a time-resolved acquisition mode allows for measurement within the cuvette as the reaction unfolds, without delay or sample disturbance.

About the VASCO KIN™️ Particle Size Analyzer

The VASCO KIN™️ is designed for precisely these types of demanding applications. Its time-resolved DLS capability is ideal for performing accurate kinetic analyses in nanomedicine, protein engineering, and formulation science.

The key is its ability to perform continuous, in situ analysis, which allows you to monitor your process as it happens. As demonstrated by Krausova et al., this eliminates guesswork and provides the clear, actionable data needed to optimize complex processes like pH-triggered disassembly. The ability to see the entire reaction profile, not just the endpoint, is what enables true process control.

For researchers and manufacturers looking to move beyond simple QC and toward a deep, mechanistic understanding of their nanoparticle systems, kinetic analysis is the future. By enabling reliable, time-resolved DLS measurement, the VASCO KIN™️ is an essential tool for getting the full story on your nanocarriers.

Source:
Krausova, K., Charousova, M., Kratochvil, Z., et al. (2022). Toward understanding the kinetics of disassembly of ferritins of varying origin and subunit composition. Applied Materials Today, 28, 101535.