Figure 1.

Synthesis of different SNPs. (A–D) Synthesis steps are illustrated for PPTrEOS (A), N34PEGOH (B), N34PEGNH2(C) and N34PEGCOOH (D). (E) Particle synthesis procedure is illustrated for modified SNPs. XXXX represents different commercial SNPs, including LTM40, SNTXS, SNT20L and SNTZL. PTr represents particles modified with alkyne functional groups. R′ represents different clicking reagents, including N34PEG, N34PEGOH, N34PEGNH2 and N34PEGCOOH, which are PEG chains of four repeating units terminated with –OMe, –OH, –NH₂ and –COOH functional groups, respectively. g represents that the clicking reagents were grafted to the particles via “click” chemistry.