| abstract |
The present invention provides a kind of particle, it includes: (a) spacer is polyethylene glycol (PEG) chain, and the molecular weight Mw of the spacer extended from particle (and therefore needed for length) is 3000 to 400,000；(b) deposition aid；(c) beneficial agent, wherein the spacer is directly connected to particle and the deposition aid is connected to the end of spacer. |