Nonconjugated fluorescent polymer nanoparticles by self-assembly of PIMA-g-β-CD for live-cell long-term tracking.

Fluorescent non-conjugated nanoparticles without any π-aromatic building blocks are of great interest in biological applications due to their low cytotoxicity and biocompatibility. Herein, the non-conjugated AIE-active polymer nanoparticles bearing β-cyclodextrin (β-CD-PNs) were obtained through self-assembly of amphiphilic poly(isobutylene-alt-maleic anhydride)-g-β-CD (PIMA-g-β-CD). Unexpectedly, β-CD-PNs without conventional AIE fluorophores showed strong fluorescence emission in the aggregated state, excellent photostability and water-solubility. More interestingly, β-CD-PNs showed excellent biocompatibility and low biotoxicity after being co-incubated with HeLa cells and passaged several times. As a result, the strong blue fluorescence signals could still be detected in HeLa cells after up to 15 generations of passages and showed complete cell morphology. Furthermore, β-CD-PNs could also be used in zebrafish for bioimaging. The results indicated that β-CD-PNs was a good choice as a tracer for long-term cell tracking and in vivo imaging agent. Our research provided an effective strategy for developing low-toxicity bioprobes based on β-CD.