I'm very happy to be here and thank the organizers for this great symposium and the invitation.

So I will give you an idea about what type of work we're doing at the Federal Institute

for Materials Research and Testing.

So we're a designated metrology institute and we are in charge of producing reference

materials and also we are involved in standardization.

What I have to tell you is we won't see any results from analytical ultracentrifugation.

We value this technique.

We have a collaboration with Lisa Stiegler, Johannes Walter, and Wolfgang Polkert, but

we don't use it ourselves.

So we are a group producing different types of nanoparticles and microparticles.

So different sizes, different shapes, different surface chemistries, and we use them as reporters,

sensors, and reference materials.

So our other expertise is optical spectroscopy.

So all kinds of spatially resolved, time resolved, wavelengths resolved, luminescence techniques,

also absolute fluorescence measurements.

So that's the reason why we really like our systems which are emissive.

And this could be, for instance, lancerite-based nanocrystals which come in different colors

and different sizes, shapes, whatever, with submission in the visible but also about 1,000

nanometers, then different types of quantum dots.

We make polymer particles which stick also nanoparticles into polymer particles and we

are also into silica particles.

Can we stain or label these materials with organic dyes, sensor molecules, and also oxygen-sensitive

complexes?

So in this respect, we're pretty much into characterizing nanoparticles and microparticles.

So which questions do you have to ask yourself when you have made a particle?

So just an overview of what you can do with all kinds of particles, what kind of materials

are currently pretty much in use.

So you start with size, shape, size distribution.

Then you move on to crystallinity, crystal structure, phase, because this can be relevant

for certain functional properties like luminescence, morphology.

So do you have a core system, core shell, a multi-shell system with preservation shells?

Then how thick and how tight is your surface-shielding cell?

This is really relevant for semiconductor quantum dots or lancerite-based nanoparticles

which are meso-material composition.

Do you have core shell intermixing?

Naturally surface charge, this is relevant for stability.

Then the surface ligand shell, chemical composition, binding, strange.

Can you have ligand desorption, adsorption, equilibria?

And what is about the number of surface functional groups?

So how many ligands do you have on the surface?

And how high is the number of derivatizable functional groups?

This is relevant when you want to process your particle, when you want to bind a biomolecule

to it or a pack ligand.

And then naturally the functional properties, so luminescence, magnetic, catalytic properties,

whatever, and toxicity risk assessment.

So what is so relevant about surface functional groups and ligands?

So they control the dispersibility, the colloidal stability of your nanomaterial.

Then if you want to tune the hydrophilicity, hydrophobicity of your material, you may have

to go for ligand exchange or encapsulation protocols.

You need these species to bind something to your nanoparticle, to use it as reporter or