Particle size: what nanometers tell you

In brief

Particle size is the diameter of a capsule or droplet, usually given in nanometers (nm). A nanometer is one millionth of a millimeter. Measured capsule size: less than 200 nm. A size figure describes the capsule.

The scale

A single human hair is many hundreds of carriers wide. Most carrier systems used in skincare, from liposomes to lipid nanoparticles, are designed somewhere between a few tens and a few hundred nanometers. Regulators draw their own lines on this scale, and those lines matter for labeling. They are explained on Is it nano? Definitions and regulation.

Our measured size

NanoVeil is Vegalab's multi-layer nano-encapsulation platform. The platform is summarized on the Technology hub. How the shell is built is on How encapsulation works.

How size is measured

The most common method for capsules in liquid is dynamic light scattering (DLS), standardized in ISO 22412. A laser passes through a diluted sample. Small particles move faster in the liquid than large ones, which makes the scattered light flicker faster. The instrument converts that flicker into a size.

Three things belong next to any DLS figure:

• Which average. DLS reports an intensity-weighted mean, often called the Z-average. A few large particles pull it up. Number-weighted and volume-weighted averages from the same sample give smaller figures. A size quoted without its basis cannot be compared with another.
• The spread. The polydispersity index (PDI) describes how uniform the sample is. A low PDI means most particles are close to the average; a high PDI means the average means little on its own.
• The state of the sample. Size is measured in a diluted suspension. A capsule in a finished serum sits in a different environment, with other ingredients around it.

Electron microscopy shows individual capsules and their shape, but only a small number of them, after drying. Laser diffraction covers larger particles. Each method answers a slightly different question, which is why the method is part of the claim. How each kind of measurement is graded is on Evidence levels and How we test.

What size tells you

• Suspension stability. Smaller, uniform capsules stay evenly dispersed in a serum for longer and are less likely to settle.
• Appearance and feel. Very small capsules scatter little light, so the serum can look clear or translucent and spread lightly.
• Surface area. The smaller the capsule, the more surface there is per gram of material, which affects how the shell interacts with its surroundings. It is one of the variables behind the release behavior described on Controlled release.
• Consistency between batches. Size and spread are practical quality measures. A batch that sits outside its usual range signals a process change.

How size fits alongside the other design choices in a carrier is on Carrier systems compared.

Reading a size figure

Size is a physical dimension. It describes the capsule itself. NanoVeil is designed to release its active on the skin surface.

Performance comes from testing. Two carriers of the same size can behave very differently depending on what they are made of. Statements about how skin looks or feels after use come from testing of the finished product on people.

Safety turns on composition. Whether a material raises a safety question depends on its composition, whether it dissolves or breaks down, and how it is used. See Are nano ingredients safe?.

Pores. How pores actually work is covered on the pore size myth.

Where this applies

The capsule described here is the NanoVeil carrier used across the NanoSerum range, including the Hyaluronic Skin Repair vial set and the Hydrating NanoSerum vial set. Terms on this page are defined in the glossary.

References

The studies below describe the technology in general.

1. International Organization for Standardization. ISO 22412:2017 Particle size analysis: Dynamic light scattering (DLS).
2. Danaei M, Dehghankhold M, Ataei S, et al. Impact of particle size and polydispersity index on the clinical applications of lipidic nanocarrier systems. Pharmaceutics. 2018;10(2):57.