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To balance the stability and the particle size of polymeric micelles, star-shaped copolymers Hx-yne-N 3 -PEG containing both alkynyl and azido groups were synthesized from hyperbranched 2,2-bismethylolpropionic acid polyester (H20 with 16 hydroxyl, H30 with 32 hydroxyl, H40 with 64 hydroxyl) to develop interlayer-crosslinked micelles by click chemistry. The results of dynamic light scattering indicate that the crosslinking could enhance the stability of polymeric micelles. The crosslinked micelles are regular nanosized (approximately 20 nm) spheres observed by a transmission electron microscope. The crosslinked micelles have better drug loading capacity and more sustained drug release behavior than the un-crosslinked micelles.

To improve the stability of polymeric micelles, here we describe interlayer-crosslinked micelles prepared from star-shaped copolymer via click chemistry. The formation of interlayer-crosslinked micelles was investigated and confirmed by proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and fluorescence spectroscopy. The morphology of un-crosslinked micelles and crosslinked micelles observed by transmission electron microscope is both uniform nano-sized spheres (approximately 20 nm). The crosslinking enhances the stability of polymeric micelles and improves the drug loading capacity of polymeric micelles. The interlayer-crosslinked micelles prepared from star-shaped copolymer and a crosslinker containing a disulfide bond are reduction-responsive and can release the drug quickly in the presence of the reducing agents such as glutathione (GSH). [ABSTRACT FROM AUTHOR]

Polyion complex (PIC) micelles were prepared by self-assembly of block-graft polycation monomethoxy poly(ethylene glycol)- block-(poly(ε-caprolactone)- graft-polyethylenimine) (PEG- b-(PCL- g-PEI)) and hyperbranched polyanion sodium carboxyl-modified hyperbranched polyesters (Hx-COONa, x = 20, 30, 40). The results from commonly used MTT assay indicated that PIC micelles had good biocompatibility. PIC micelles with N/COO of 8/3 had appropriate size (sub-110 nm) and moderate zeta potential (~3 mV). PIC micelles were nano-sized spheres, and the average size was about 50 nm. PIC micelles had high drug loading capacity for hydrophilic drugs such as doxorubicin (DOX) hydrochloride and released the drugs under the influence of pH and ionic strength. [ABSTRACT FROM AUTHOR]

The biodegradability of polyacrylate derivatives is of great importance to their applications in medical and biological science. Here we design a six-membered carbonate monomer 2-(2-bromoisobutyrylamido)trimethylene carbonate (BrTMC) with an atom transfer radical polymerization (ATRP) initiating group 2-bromoisobutyryl. Ring-opening polymerization (ROP) of BrTMC and 2,2-dimethyltrimethylene carbonate (DTC) was carried out to synthesize copolycarbonate P(BrTMC-DTC), which further initiated ATRP of hydroxyethyl methacrylate (HEMA) to prepare biodegradable amphiphilic graft polymer P(BrTMC-DTC)- g -PHEMA. P(BrTMC-DTC)- g -PHEMA was able to form the micelles by self-assembly. [ABSTRACT FROM AUTHOR]