Wenzhao Liu

Bio: Wenzhao Liu is an academic researcher from Hunan University. The author has contributed to research in topics: Self-healing hydrogels & Photonic crystal. The author has an hindex of 2, co-authored 4 publications receiving 17 citations.

Novel robust ion-specific responsive photonic hydrogel elastomers

Abstract: Embedded photonic crystal hydrogels and responsive photonic crystal microspheres that can change structural color as a result of external stimuli have shown great potential for various applications, but their practical applications have been greatly limited due to the poor mechanical properties of hydrogel materials and their sometimes unideal optical properties. Although some progress has been achieved, it is still a challenge to develop photonic crystal hydrogel materials with the desired mechanical properties and structural color. Inspired by the excellent mechanical properties of polyurethane, this article presents a novel smart composite material, which combines nonionic UV-curable polyurethane and cross-linked polystyrene-co-poly(N-isopropylacrylamide) (PS-co-PNIPAM) microspheres for the first time. This photonic hydrogel demonstrates the desired optical properties and a narrow reflection peak half-width, while the tensile strength of the cured elastomers changes between 0.1 MPa and 0.43 MPa when the swelling ratio is changed; this multifunctional material can recover from deformation to its original size quickly. As proof-of-concept, SCN− was selected as a target analyte. A hydrogel sensor enables the detection of SCN− ions quantitatively and selectively in water through the ion-specific deswelling behavior of hydrogels (the Hofmeister series principle) and corresponding changes in the wavelength of the diffraction peak; the limit of detection is 5 μM. Our strategy is a straightforward way to design simple smart materials whose response and mechanical properties can be tuned through the judicious choice of the hydrophilic group type and content, extending the potential application of photonic hydrogels.

Melting of Colloidal-Crystal Films

Abstract: We study melting mechanisms in single and polycrystalline colloidal films composed of diameter-tunable microgel spheres with short-ranged repulsive interactions and confined between two glass walls. Thick films ($g4$ layers), thin-films ($\ensuremath{\le}4$ layers), and monolayers exhibit different melting behaviors. Thick films melt from grain boundaries in polycrystalline solid films and from film-wall interfaces in single-crystal films; a liquid-solid coexistence regime is observed in thick films but vanishes at a critical thickness of 4 layers. Thin solid films (2 to 4 layers) melt into the liquid phase in one step from both grain boundaries and from within crystalline domains. Monolayers melt in two steps with a middle hexatic phase.

Three-dimensional/two-dimensional photonic crystal hydrogels for biosensing

Abstract: Photonic crystals (PCs) have attracted intense interest for sensing applications. Photonic crystal hydrogels (PCHs) consist of both periodic PCs and stimuli-responsive hydrogels, which can act as a sensing system for the detection of specific analytes. In PCHs, the hydrogel system undergoes volume phase transitions (VPT, swelling or shrinkage) upon exposure to external stimuli. The VPT of the hydrogel causes the photonic stopband of the PCs within the hydrogel to change, which shifts the Bragg diffraction peak wavelengths. Based on this sensing mechanism, a variety of PCH sensors that can respond to external stimuli, such as humidity, temperature, pH, hazardous chemicals and biological species, have been reported. In this review, we overview the response mechanism, preparation methods, and biosensing applications of three-dimensional (3D) and two-dimensional (2D) PCHs. 3D and 2D PCH biosensors are systematically summarized according to the types of the target analytes. At the end of this review, we also propose the prospects of PCHs in the field of biosensing.

Thermochromic Hydrogel-Functionalized Textiles for Synchronous Visual Monitoring of On-Demand In Vitro Drug Release.

Abstract: In vitro drug release systems have recently received tremendous attention because they allow noninvasive, convenient, and prolonged administration of pharmacological agents. On-demand epidermal dru...