Nanostructured Thermal Responsive Materials Synthesized by Soft Templating

Light-driven modulation of electrical conductance with photochromic switches: bridging photochemistry with optoelectronics

Photochromic conducting molecules have emerged because of their unique capacity to modulate electrical conductivity upon exposure to light, toggling between high and low conductive states. This unique amalgamation has unlocked novel avenues for the application of these materials across diverse areas in optoelectronics and smart materials. The fundamental mechanism underpinning this phenomenon is based on the light-driven isomerization of conjugated π-systems which influences the extent of conjugation. The photoisomerization process discussed here involves photochromic switches such as azobenzenes, diarylethenes, spiropyrans, dimethyldihydropyrenes, and norbornadiene. The change in the degree of conjugation alters the charge transport in both single molecules and bulk states in solid samples or solutions. This article discusses a number of recent examples of photochromic conducting systems and the challenges and potentials of the field.

Fabrication of bicontinuous double networks as thermal and pH stimuli responsive drug carriers for on-demand release

The fabrication, via a two steps approach, of a novel bicontinuous Double Network (BCDN) material is reported. We first use a bicontinuous emulsion as template to obtain a poly(butyl acrylate) (PBA) and poly(acrylic acid) (PAA) bicontinuous amphiphilic material. The material is then swollen with the precursor of a second hydrophilic polymer (PNIPAM, poly(N-isopropylacrylamide)). After polymerization of these precursors, the two responsive polymers, PNIPAM and PAA, form a double-network within a bicontinuous templated material, i.e. a bicontinuous double network (BCDN) material. The advantages of using such unique and complex double network architecture are manifold. PBA increases the mechanical properties of the hydrogel all together with the hydrophilic double network that also decouples the pH and temperature responsiveness. Among different possible applications, we tested this responsive hydrogels for its biomedical application. It can be used as pH and temperature sensitive devices for on-demand drug delivery. In addition, the release of a drug confined in the amphiphilic bicontinuous structure follows different kinetics profiles, depending on pH and temperature. This last result indicates that it is possible to control and regulate the release of an encapsulated drug according to the fluctuations of physiological conditions.

Novel phthalocyanine-based micelles/PNIPAM composite hydrogels: spatially/temporally controlled drug release triggered by NIR laser irradiation

Near-infrared (NIR) light-responsive hydrogels hold significant potential for biomedical application, especially in the remote-controlled release of anticancer drugs.

pH-Sensitive Chitosan-Sodium Phytate Core-Shell Hollow Beads and Nanocapsules for the Encapsulation of Active Ingredients

The oral administration of nutraceuticals and vitamins is the most compliant route because of its minimal invasiveness, painlessness, ease of use, and cost effectiveness. To overcome the possible destruction and low availability induced by the harsh gastrointestinal environment, we use sodium phytate as a cross-linker to fabricate pH-sensitive core-shell chitosan hollow beads and nanocapsules through the ionic linking method for the controllable release of active ingredients. Texture profile analysis, transmission electron microscopy, dynamic light scattering, and scanning electron microscopy were used to characterize the morphologies and behaviors of the beads and nanocapsules. The size of the beads could be adjusted from 0.1 to 10 mm, and the diameter of the nanocapsules was 50-100 nm. The addition of pectin in sodium phytate remarkably increased the hardness of the chitosan beads. Nile blue A was used as a model active ingredient for loading into the chitosan beads with the maximum encapsulation efficiency (EE) and loading capacity of 96.07 ± 2.45% and 9.61 ± 0.29%, respectively. Polyphenols including catechin, epicatechin, epigallocatechin-3-gallate, and proanthocyanidin were successfully loaded into the chitosan nanocapsules with an EE of above 90%. The cumulative release of Nile blue A from the beads at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 20% and more than 80%, respectively. Similarly, the cumulative release of polyphenols in the nanocapsules at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 30% and more than 70%, respectively. In sum, chitosan-sodium phytate with and without pectin could form pH-responsive macro- and nanoscale carriers suitable for the encapsulation and controlled release of active ingredients.

Micellar and bicontinuous microemulsion structures show different solute–solvent interactions: a case study using ultrafast nonlinear infrared spectroscopy

Using aqueous and organic probes to simultaneously explore the structural dynamics of reverse micellar and bicontinuous microemulsion structures.