Supramolecular Dynamics as Origin for Thermally Induced Insoluble-to-Soluble-to-Insoluble Transitions of Copolymers in Water

Platinum-Incorporating Poly(N-vinylpyrrolidone)-poly(aspartic acid) Pseudoblock Copolymer Nanoparticles for Drug Delivery

Cisplatin-incorporating pseudoblock copolymer nanoparticles with high drug loading efficiency (ca. 50%) were prepared built on host-guest inclusion complexation between β-cyclodextrin end-capped poly(N-vinylpyrrolidone) block and admantyl end-capped poly(aspartic acid) block, followed by the coordination between cisplatin and carboxyl groups in poly(aspartic acid). The host-guest interaction between the two polymer blocks was examined by two-dimensional nuclear overhauser effect spectroscopy. The size and morphology of nanoparticles formed were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and atomic force microscopy. The size control of nanoparticles was carried out by varying the ratio of poly(N-vinylpyrrolidone) to poly(aspartic acid). The nanoparticles were stable in the aqueous medium with different pH values but disintegrated in the medium containing Cl(-) ions. The in vitro and in vivo antitumor effects of cisplatin-loaded nanoparticles were evaluated. The biodistribution of the nanoparticles in vivo was studied by noninvasive near-infrared fluorescence imaging and ion-coupled plasma mass spectrometry. It was found that cisplatin-loaded nanoparticles could effectively accumulate in the tumor site and exhibited significant superior in vivo antitumor activity to the commercially available free cisplatin by combining the tumor volume, body weight, and survival rate measurements.

Nonionic cyclodextrin based binary system with upper and lower critical solution temperature transitions via supramolecular inclusion interaction

A nonionic binary aqueous interaction system consisting of β-cyclodextrin trimer (β-CD3) and naphthalene-terminated poly(ethylene glycol) (PEG-NP2), which has tunable upper critical solution temperature (UCST) behavior around room temperature and lower critical solution temperature (LCST) behavior at high temperature, was investigated. In the UCST transition, gel-like aggregates form because of supramolecular inclusion complexation between β-CD3 and PEG-NP2. During LCST transition, PEG-NP2 becomes insoluble in water, which results in its precipitation. The effects of concentration, stoichiometry of the two components, and electrolyte on UCST behavior are discussed. This study provides a new nonionic thermoresponsive material.

Oligomeric epoxide-amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

2-Amino-N-isopropylacetamide and α-amino-ε-caprolactam were reacted with glycerol diglycidyl ether to give novel oligomeric thermoresponsive epoxide–amine adducts. These oligomers exhibit a lower critical solution temperature (LCST) behavior in water. The solubility properties were influenced with randomly methylated β-cyclodextrin (RAMEB-CD) and the curing properties of the amine–epoxide mixtures were analyzed by oscillatory rheology and differential scanning calorimetry, whereby significant differences in setting time, viscosity, and stiffness were observed.