Monoolein cubic phases containing cinnamic acid, poly(ethyleneimine) and gold nanoparticle and their UV- and NIR-responsive release property

Light-responsive polyurethanes: classification of light-responsive moieties, light-responsive reactions, and their applications

Stimuli responsiveness has been an attractive feature of smart material design, wherein the chemical and physical properties of the material can be varied in response to small environmental change. Polyurethane (PU), a widely used synthetic polymer can be upgraded into a light-responsive smart polymer by introducing a light-sensitive moiety into the polymer matrix. For instance, azobenzene, spiropyran, and coumarin result in reversible light-induced reactions, while o-nitrobenzyl can result in irreversible light-induced reactions. These variations of light-stimulus properties endow PU with wide ranges of physical, mechanical, and chemical changes upon exposure to different wavelengths of light. PU responsiveness has rarely been reviewed even though it is known to be one of the most versatile polymers with diverse ranges of applications in household, automotive, electronic, construction, medical, and biomedical industries. This review focuses on the classes of light-responsive moieties used in PU systems, their synthesis, and the response mechanism of light-responsive PU-based materials, which also include dual- or multi-responsive light-responsive PU systems. The advantages and limitations of light-responsive PU are reviewed and challenges in the development of light-responsive PU are discussed.

Monoolein Cubic Phase Including Hydrophobized Modified Gelatin and Poly(ethyleneimine) and Its Effect on the Stability of Retinyl Palmitate

Retinyl palmitate (RP) was added in monoolein (MO) cubic phase including decanoyl poly(ethyleneimine) (DePEI) and decanoyl gelatin (DeGel) in its water channel. RP, DePEI, and DeGel was incorporated In the cubic phase without structural disintegration, as confirmed by transmission electron microscopy. Differential scanning calorimetric and polarized optical microscopic analysis showed that adding the additives reduces phase transition temperature of cubic phase by 2 °C to 3 °C. The time-dependent chemical stability of RP added in the cubic phase was analyzed for 4 weeks at 5 °C, 20 °C, 30 °C, and 40 °C, using RP loaded in o/w emulsion as a control. The chemical stability of RP added in cubic phase containing DePEI and DeGel was somewhat higher as compared to the RP added in the cubic phase without DeGel/DePEI, possibly because DeGel/DePEI complex might shield RP from its environment by blocking the water channels inside the cubic phase. Moreover, the chemical stability of RP added in the cubic phase was comparatively higher than RP added in o/w emulsion.

Stimuli-Responsive Lyotropic Liquid Crystalline Nanosystems with Incorporated Poly(2-Dimethylamino Ethyl Methacrylate)-b-Poly(Lauryl Methacrylate) Amphiphilic Block Copolymer

There is an emerging need to evolve the conventional lyotropic liquid crystalline nanoparticles to advanced stimuli-responsive, therapeutic nanosystems with upgraded functionality. Towards this effort, typically used stabilizers, such as Pluronics^®, can be combined or replaced by smart, stimuli-responsive block copolymers. The aim of this study is to incorporate the stimuli-responsive amphiphilic block copolymer poly(2-(dimethylamino)ethyl methacrylate)-b-poly(lauryl methacrylate) (PDMAEMA-b-PLMA) as a stabilizer in lipidic liquid crystalline nanoparticles, in order to provide steric stabilization and simultaneous stimuli-responsiveness. The physicochemical and morphological characteristics of the prepared nanosystems were investigated by light scattering techniques, cryogenic-transmission electron microscopy (cryo-TEM), X-ray diffraction (XRD) and fluorescence spectroscopy. The PDMAEMA-b-PLMA, either individually or combined with Poloxamer 407, exhibited different modes of stabilization depending on the lipid used. Due to the protonation ability of PDMAEMA blocks in acidic pH, the nanoparticles exhibited high positive charge, as well as pH-responsive charge conversion, which can be exploited towards pharmaceutical applications. The ionic strength, temperature and serum proteins influenced the physicochemical behavior of the nanoparticles, while the polymer concentration differentiated their morphology; their micropolarity and microfluidity were also evaluated. The proposed liquid crystalline nanosystems can be considered as novel and attractive pH-responsive drug and gene delivery nanocarriers due to their polycationic content.