Bioinspired nanoplatform for enhanced delivery efficiency of doxorubicin into nucleus with fast endocytosis, lysosomal pH-triggered drug release, and reduced efflux.

A novel bioinspired nanoplatform capable of fast endocytosis, lysosomal pH-triggered drug release, and reduced drug efflux based on PBA-PEG-b-P(Glu-co-GluDA) copolymer was developed in this study. The synthesized copolymer could facilitate doxorubicin encapsulation with relatively high drug-loading content and efficiency. Inspired by mussel byssal threads, a core crosslinking strategy based on the coordination between catechol and ferric ions was introduced to improve the stability of nanomicelles and realize lysosomal pH-controlled drug release. This nanoplatform could maintain integrity even after being dissolved in a good solvent, demonstrating its the potential to withstand infinite dilution of plasma after intravenous injection. Moreover, this nanoplatform demonstrated lysosomal pH-triggered drug release, and the cumulative release amount of doxorubicin under a simulated lysosomal condition was 13 times higher than that under a simulated plasma condition. Moreover, as a result of the high binding capacity between phenylboronic acid (PBA) and sialic acid on the surface of human hepatoma cell line (HepG2), the fast and enhanced endocytosis in addition to lysosomal pH-triggered release property and significantly low efflux, this nanoplatform exhibits improved delivery efficiency of doxorubicin into the nucleus and notably outstanding antiproliferative effects compared with doxorubicin. Furthermore, the PBA modification remarkably increased the mean fluorescence intensity of this nanoplatform endocytosed by HepG2 cells to twice that of doxorubicin after one hour of incubation. The nanoplatform exhibited an inhibition rate of 70% against tumor growth. Thus, this novel nanoplatform based on PBA-PEG-b-P(Glu-co-GluDA) copolymer displayed multifunctionality and exhibited great potential as an intelligent nanoplatform for antitumor drug delivery.