The liposomes in which the messenger RNA is enclosed are well tolerated by the body and used in 30% of tablet drugs, shampoos and toothpastes etc..... This is Polyethylene Glycol which is very widespread [1]

Nanoparticles" are all particles between 1 and 100 nanometers in size - this is the order of magnitude of many viruses. Tolerance to nanoparticles depends largely on their composition. Some are highly toxic, such as those from tobacco smoke or diesel engines.

The lipid nanoparticles used in messenger RNA vaccines are about 80 nanometers in size and are made of lipids similar to those found in the human body; they do not contain metals (silver, titanium, gold, etc...).

Swissmedic [2], the Swiss drug regulatory agency, considers these lipid nanoparticles to be well tolerated by the body, as they are already used in several drugs approved in Switzerland (including drugs used in cancer treatment). Their medicinal use in Switzerland is strictly regulated by Swissmedic.

1-Ref: *BJA. Allergic reactions to the first COVID-19 vaccine: is polyethylene glycol (PEG) the culprit?