Preparation, Characterization and Drug Release Behavior of 5-Fluorouracil Loaded Carboxylic Poly(ε-caprolactone) Nanoparticles

Functional biodegradable polymers via ring-opening polymerization of monomers without protective groups

Biodegradable polymers are of current interest and chemical functionality in such materials is often demanded in advanced biomedical applications. Functional groups often are not tolerated in the polymerization process of ring-opening polymerization (ROP) and therefore protective groups need to be applied. Advantageously, several orthogonally reactive functions are available, which do not demand protection during ROP. We give an insight into available, orthogonally reactive cyclic monomers and the corresponding functional synthetic and biodegradable polymers, obtained from ROP. Functionalities in the monomer are reviewed, which are tolerated by ROP without further protection and allow further post-modification of the corresponding chemically functional polymers after polymerization. Synthetic concepts to these monomers are summarized in detail, preferably using precursor molecules. Post-modification strategies for the reported functionalities are presented and selected applications highlighted.

Synthesis of functionalized Pluronic-b-poly(ε-caprolactone) and the comparative study of their pendant groups on the cellular internalization behavior

This study focuses on the synthesis of Pluronic-b-poly(ε-caprolactone) bearing benzyl-oxycarbonylmethyl and carboxylic groups and the comparative study to investigate the influence of the different pendant groups on the cellular behavior. The functionalized Pluronic-b-poly(ε-caprolactone) bearing two kinds of pendant groups are synthesized via ring-opening polymerization of ε-caprolactone and 6-(benzyl-oxycarbonyl methyl)-ε-caprolactone and followed by deprotection respectively. The structure of the copolymers is confirmed and the polymeric micelles are formed by an emulsion/solvent evaporation technique. The critical micelle concentrations are improved compared with Pluronic F127, the morphologies of the micelles are spherical with the diameter on nano scale and good colloidal stability. The copolymers have good cytocompatibility and the comparative study reveals that cellular internalization, digesting by lysosome and intracellular distribution are affected by the pendant groups, moreover, the endocytosis pathway is determined by the pendant groups. Therefore, the definite internalization mechanism is beneficial for the design of polymeric micellar carriers to achieve intra- or extracellular modes of drug delivery and provide better access to either cell membrane or intracellular organelles.

Synthesis, characterization and drug release behavior of poly(1-vinyl 1,2,4-triazole) hydrogels prepared by gamma irradiation

Crosslinked poly(1-vinyl 1,2,4-triazole) (PVTAz) hydrogels in the form of rod and hollow cylinder (thin and thick wall) have been prepared by (60)Co γ-radiation initiated simultaneous polymerization and crosslinking of 1-vinyl 1,2,4-triazole in the presence of water. In binary aqueous systems, the degree of gelation decreased with the increasing water content. The swelling results obtained by using different form of hydrogels showed that the thin wall hollow cylinder hydrogels perform better than other hydrogels. Structural, morphological and thermal characterizations of the hydrogels were carried out with several techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, swelling measurements, thermogravimetry, and differential scanning calorimetry. The effects of time, pH, temperature, ionic strength, and salt and solvent type on the swelling behavior of thin wall hollow cylinder hydrogels were also investigated. Swelling equilibrium was attained in 2 days. Thin wall hollow cylinder PVTAz hydrogels originally swelled to 3000% (by volume), and depending on the pH value, no sharp change was observed on the swelling curve. Swelling values of hydrogels showed that the swelling ratio increase with the increasing temperature in the range of 4-20°C. The swelling ratios of the gels decreased with increasing ionic strength. Hydrogels have shown the maximum contraction in the presence of LiCl. 5-Fluorouracil (5-FU) was loaded on PVTAz hydrogels by using incorporation and adsorption methods. Both methods show the similar release profiles. Time-dependent release of 5-FU was achieved within 48 h by the success of 65%. All these results showed that PVTAz hydrogels are suitable for the release of 5-FU in the applications of long-term cancer treatment.