A new class of supramolecular and biomimetic glycopolymer/poly(-caprolactone)-based polypseudorotaxane/glycopolymer triblock copolymers (poly(D-gluconamidoethyl methacrylate)-PPR-poly(D-gluconamidoethyl methacrylate), PGAMA-PPR-PGAMA), exhibiting controlled molecular weights and low polydispersities, was synthesized by the combination of ring-opening polymerization of-caprolactone, supramolecular inclusion reaction, and direct atom transfer radical polymerization (ATRP) of unprotected D-gluconamidoethyl methacrylate (GAMA) glycomonomer. The PPR macroinitiator for ATRP was prepared by the inclusion complexation of biodegradable poly(-caprolactone) (PCL) with R-cyclodextrin (R-CD), in which the crystalline PCL segments were included into the hydrophobic R-CD cavities and their crystallization was completely suppressed. Moreover, the self-assembled aggregates from these triblock copolymers have a hydrophilic glycopolymer shell and an oligosaccharide threaded polypseudorotaxane core, which changed from spherical micelles to vesicles with the decreasing weight fraction of glycopolymer segments. Furthermore, it was demonstrated that these triblock copolymers had specific biomolecular recognition with concanavalin A (Con A) in comparison with bovine serum albumin (BSA). To the best of our knowledge, this is the first report that describes the synthesis of supramolecular and biomimetic polypseudorotaxane/glycopolymer biohybrids and the fabrication of glucose-shelled and oligosaccharide-threaded polypseudorotaxane-cored aggregates. This hopefully provides a platform for targeted drug delivery and for studying the biomolecular recognition between sugar and lectin.

Two types of three-arm or four-arm star-shaped hydroxy-terminated poly(-caprolactone) (PCL) were successfully synthesized via the ring-opening polymerization of caprolactone (CL) with multifunctional initiator, such as trimethylolpropane (TMP) or pentaerythritol (PTOL), and stannous octoate (SnOct2) catalyst in bulk at 110℃. The number-average molecular weight of PCL is proportional to the molar ratio of monomer to initiator. 1H NMR spectroscopy of the resulting PCL indicates that it contains a primary hydroxy end group in each arm. The star-shaped PCL with hydroxy end groups can be used as a macroinitiator for block copolymerization with DL-3-methylglycolide (MG) using SnOctcatalyst in bulk at 115℃. 1H NMR spectra of the resulting block copolymers show that the molecular weights and the unit compositions of the block copolymers were controlled by the molar ratios of MG monomer to hydroxy groups of PCL and MG to CL in feed, respectively. Moreover, the molecular weights of the resulting block copolymers linearly increased with the increase of the molar ratios of MG to CL in feed. The molecular weight distributions of the block copolymers were rather narrow (Mw/Mn) 1.09-1.26). 13C NMR spectra of the resulting block copolymers clearly show their diblock structures, that is, PCL as the first block and poly(DL-lactic acid-alt-glycolic acid) (DL-PLGA50) with alternating structures of lactyl and glycolyl units as the second block. Therefore, two types of three-arm or four-arm star-shaped diblock copolyesters comprising the first block PCL and the second block DL-PLGA50 were successfully synthesized via the sequential ring-opening polymerization of CL with multifunctional initiator and Snoctcatalyst and then followed by copolymerization with MG.

Biodegradable chitosan-graft-poly(L-lactide)(CS-g-PLLA) hybrid amphiphiles were prepared through direct grafting of a PLLA precursor to the backbone of CS. The average number of PLLA grafts per CS could be adjusted by the feed ratio of PLLA to CS, and it varied from 1.3 to 16.8. Moreover, both the crystallization rate and degree of crystallization of PLLA grafts with these graft copolymers could be adjusted by the chain length of PLLA and the number of PLLA grafts per CS, respectively. Meanwhile, CS-g-PLLA exhibited good solubility in some nonpolar and polar organic solvents compared with the original CS. Furthermore, self-assembled nanoparticles could be generated by direct injection of these graft copolymer solutions into distilled water, and their critical aggregation concentration decreased with increasing number of PLLA grafts per CS. The average size of the nanoparticles (25-103nm) could be adjusted through the graft copolymer composition and the graft copolymer concentration, which was very different from the observations in ordinary PLLA-b- poly(ethylene oxide) amphiphiles. Significantly, this will provide a convenient method not only to combine the bioactive functions of CS with the good mechanical properties of biodegradable polymers, but also to generate nanoparticles with adjustable sizes for targeted drug release.

A new class of linear-dendron-like poly(ε-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) copolymers with unsymmetrical topology was synthesized via controlled ring-opening polymerization (ROP) of ε-caprolactone (CL) followed by a click conjugation with azide-terminated PEO (PEO-N3). The dendron-like PCL terminated with a clickable alkyne group (Dm-PCL, m) 0, 1, 2, and 3) was for the first time synthesized from the ROP of CL monomer using a propargyl focal point dendrons Dm with primary amine groups as the initiators and stannous octoate as catalyst in bulk at 130℃. Then, the linear-dendron-like Dm-PCL-b-PEO copolymers were obtained by the click conjugation of Dm-PCL with PEO-N3 using PMDETA/CuBr as catalyst in DMF solution at 35℃. Their molecular structures and physical properties were in detail characterized by FT-IR, NMR, MALLS-GPC, DSC, and WAXD. Both DLS and TEM analyses demonstrated that the biodegradable micelles and vesicles with different sizes (less than 100 nm) self-assembled from these Dm-PCL-b-PEO copolymers in aqueous solution, and both the PEO composition and the linear-dendron-like architecture of copolymers controlled the morphology and the average size of nanoparticles. To the best of our knowledge, this is the first report that describes the synthesis of linear-dendron-like PCL-b-PEO block copolymers via the combination of ROP and click chemistry. Consequently, this provides a versatile strategy not only for the synthesis of biodegradable and amphiphilic block copolymers with linear-dendron-like architecture but also for fabricating biocompatible nanoparticles with suitable size for controlled drug release.

A series of derivatized arylamine initiators were used to generate chain-end functionalized glycopolymers by cyanoxyl-mediated free-radical polymerization. Significant features of this strategy include the capacity to produce polymers of low polydispersity (PDI < 1.5) under aqueous conditions using unprotected monomers bearing a wide range of functional groups. In addition, the presence of a phenyl ring simplifies calculation of polymer saccharide content and molar mass by 1H NMR. It is particularly noteworthy, however, that derivatized arylamine initiators in conjunction with the presence of a terminal cyanate group provide a convenient approach for synthesizing polymers with a variety of distinct functional groups at R and ö chain ends. In the process, the capacity to label glycopolymers or otherwise conjugate them to proteins or other molecules is greatly enhanced.