Coassembling functionalized glycopolypeptides to prepare pH-responsive self-indicating nanocomplexes to manipulate self-assembly/drug delivery and visualize intracellular drug release.

The pH-responsive polymeric micelles (PMs) have been widely used as smart nano drug delivery systems to treat tumors. However, synchronously manipulating these PMs' self-assembly properties, drug release dynamics and tracing their pH-dependent intracellular fate remain challenges. Herein, we have first synthesized hyaluronic acid (HA) based glycopolypeptides modified by tetraphenylethylene (TPE) and a pH-sensitive doxorubicin (DOX) prodrug through Diels-Alder reaction, respectively. Then, the pH-responsive nanocomplexes (NCs) were prepared by coassembling the two obtained glycopolypeptides with different formulations. Controllable size within the range of 60-125 nm and morphologies like spherical, vesicular and oblate micelles can be easily accomplished by using this method; High drug encapsulating and loading efficiency can be easily realized and adjusted within a range of 86-97% and 7-25%, respectively; Acid sensitive drug release dynamics of these NCs are also tunable by using this way. Additionally, the programmed drug release induced by subtle pH variations can be extracellularly self-indicated by detecting the blue AIE changes of the TPE units through fluorescence resonance energy transfer (FRET) effect between DOX and TPE. More importantly, the dynamic pH-triggered DOX release can be easily traced inside the tumor cells by visualizing blue emission changes of the TPE through the FRET effect. In addition, both the size and the shape can affect the endocytic routes of the NCs; The HA coated NCs targeting the tumor cells can effectively inhibit the proliferation of the HeLa cells. This work can provide a new route to acquire the stimuli-responsive self-indicating PMs with the ability to adjust their self-assembly properties and their pH-triggered drug release dynamics, and even to simultaneously visualize the PMs' intracellular fate in a real-time.

Structure and Oxidation Effects on Conformation and Thermoresponsiveness of the OEGylated Poly(glutamic acid)-Bearing Side-Chain Thioether Linkers.

A series of side-chain thioether-linked OEGylated poly(glutamic acid) (PGAs) have been synthesized by "thiol-ene" synthetic methodology, where both the oligo-ethylene glycol (OEG) length and the hydrophobic linkers at the side chains are varied to learn how these structural features affect the secondary structure and thermoresponsive behaviors in water. Before side-chain oxidation, the structural factors affecting the α-helicity include the backbone length, the OEG length, and the hydrophobic linkers' length at the side chains; however, the OEG length plays the most crucial role among these factors because longer OEG around the peripheral side chains can stop water penetration into the backbone to disturb the intramolecular H bonds, which finally allows stabilizing the α-helix; after the oxidation, the polypeptides show increased α-helicity because of the enhanced hydrophilicity. More interestingly, a rare oxidation-induced conformation transition from the ordered ß-sheet to the ordered α-helix can be achieved. In addition, only the OEGylated poly(glutamic acids) (PGAs) with shorter hydrophobic linkers and longer OEG can display the thermoresponsive properties before the oxidation but the subsequent oxidation can cause the polypeptides bearing longer hydrophobic linkers to exhibit the thermosensitivity since sulfone formation at the side chain can lead to final hydrophilicity-hydrophobicity balance. This work is meaningful to understand the secondary structure-associated solution behaviors of the synthetic polypeptides.

Using Polypeptide Bearing Furan Side Chains as a General Platform to Achieve Highly Effective Preparation of Smart Glycopolypeptide Analogue-Based Nano-Prodrugs for Cancer Treatment.

Although several synthetic polypeptide-based nano-prodrugs (NPDs) have entered clinical trials for cancer treatment, achieving a highly effective production of the NPDs for clinical translation remains a challenge. Herein, we develop a typical preparation of pH/glutathione (GSH) dual-responsive glycopolypeptide analogue NPDs having a high drug capsulation/loading efficiency of ca. 93% and ca. 27% even based on ring-opening polymerization (ROP) of a novel and general furan-containing N-carboxyanhydride (NCA) monomer, which facilitates the Diels-Alder (D-A) side-chain functionalization by maleimide modified chemotherapy drug without using any reactive additives. High reactivity of the D-A reaction resulting in the high preparation efficiency of the NPDs is confirmed by 1H NMR and density functional theory (DFT) calculations. The self-assembled properties as well as the dual-responsiveness of the NPDs are systemically studied by particle size and zeta potential assay, transmission electron microscopy and drug-delivery dynamics. The cell uptake mechanism, intracellular drug distribution, in vitro/vivo antitumor activity evaluations and the main organ damages of the NPDs are all investigated. Our work can provide a good solution to solve the inefficient fabrication of the smart synthetic polypeptide-based micelles for cancer treatment by following this general and sophisticated platform.