Linear-dendritic Poly Research Articles

Thermoresponsive SERS Nanocapsules Constructed by Linear-Dendritic Poly(urea/malonamide) for Tunable Biomolecule Detection

In this work, thermoresponsive core–shell micelle-embedded silver nanoparticles (AgNPs) were prepared from a series of monodisperse linear-dendritic poly(urea/malonamide). Through efficient iterative synthesis, well-defined dendritic amphiphiles bearing dual functionality provide nucleation sites as excellent templates for immobilizing AgNPs on one end, while oligoethers anchor water to stabilize these micelles in water as polymer dispersions. During the heating process, linear-dendritic poly(urea/malonamide) with various ratios of hydrophilic/hydrophobic segments resulted in the size-dependent lowest critical solution temperature (LCST), ranging from 72 to 54 °C in aqueous media. As a result, the gap distances between AgNPs could be manipulated, resulting in a stronger hot spot effect using thermoresponsive nanocapsules for surface-enhanced Raman scattering (SERS) analysis. Consequently, the signal was enhanced at temperatures over the LCST. For AgNPs@TD-G1.5 thermoresponsive SERS nanocapsules, an ∼33 times enhancement during the LCST transition was obtained. The high sensitivity and stability of the intelligent AgNPs@thermoresponsive SERS nanocapsules endow them with great potential in the rapid SERS detection of small-molecule analytes by adsorbing analytes at room temperature (below the LCST) and encapsulating the analytes into micelles at high temperatures (above the LCST) in the application of monitoring trace-level and diverse analytes.

Itraconazole-loaded micelles based on linear-dendritic poly (ethylene glycol)-b-poly (ε-caprolactone)

A copolymeric micelle formulation of itraconazole (ITR-M) was prepared using linear-dendritic monoallyloxy poly (ethylene glycol)-b-poly (ε-caprolactone) (APEG-PCL) as drug carrier materials. DL and EE values of ITR-M were 5.70 ± 0.12% and 91.30 ± 1.90%, respectively. The micelle formulation enhanced the ITR solubility up to 30.42 μg/mL. In vitro release of ITR from the ITR-M was mainly drug diffusion process followed by the copolymer’s degradation. ITR-M showed similar anti-Candida albicans activity to that of crude ITR although its release of ITR was slow and continuous. The in vivo pharmacokinetic study demonstrated that the ITR-M could improve tissue distribution of ITR. In conclusion, APEG-PCL could be a potential carrier in the development of antifungal drug delivery system.

Interaction between a water-in-oil microemulsion and a linear-dendritic poly(propylene oxide)–polyglycerol block copolymer

We present small angle scattering and dielectric spectroscopy results on the influence of an amphiphilic diblock copolymer on the structure and dynamics of a microemulsion. We use a water-in-oil (w/o) droplet microemulsion based on the anionic surfactant AOT (sodium bis(2-ethylhexyl) sulfosuccinate), that forms spherical water droplets coated by a monolayer of AOT dispersed in the continuous oil matrix. The studied polymer consists of a hydrophobic poly(propylene oxide) (PPO) block and a hydrophilic hyperbranched polyglycerol with 74 glycerol units (NG74). Combining small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) we find that the droplet structure is preserved upon addition of PPO-NG74 while the interaction distance between droplets increases with increasing polymer content. From SANS we deduce that the NG74 block is located inside the droplets while the PPO extends into the oil matrix. By measuring the dc-conductivity as a function of temperature we study the dynamic percolation of the microemulsion. While the static structure of the droplet phase remains unchanged, both percolation temperature and phase separation temperature increase linearly with increasing polymer concentration. We explain this finding by a stiffening of the AOT layer induced by the polymer. By means of dielectric spectroscopy we observe two relaxations. The slower one can be related to a polarization at the interface of the water core and the AOT shell (core relaxation) and the faster one is due to the ions in the AOT-shell (cluster relaxation). Polymer addition is found to have a significant influence only on the core relaxation. We apply the cluster relaxation model to estimate the cluster size evolution with increasing polymer concentration.