A Sensitive Concentration- and Polarity-Dependent Pyrene-Derived Vibrationally Resolved Fluorescence Probe for The Polymer Interdiffusion Study.

The vibrationally resolved pyrene fluorescence probe method is once popular but now languished, because the vibrationally resolved patterns of pyrene with limited sensitivity and concentration independence have not been updated for over 50 years. During investigation on the polymer interdiffusion of a latex film, it is found that a pyrene acylhydrazone whose vibrationally resolved fluorescence pattern contradictory to those reported in pyrene and most pyrene derivatives. The pyrene acylhydrazone has sensitive concentration- and polarity-dependent fluorescence spectra (the sensitivity on polarity is at most 26 times higher than the old vibrationally resolved patterns), and the sensitivity well remains when it is copolymerized in a polymer. The vibrationally resolved spectrum of this pyrene acylhydrazone is a powerful fluorescence probe, which would be as useful as the pyrene excimer probe nowadays popular.

Fabrication of Temperature- and Alcohol-Responsive Photonic Crystal Hydrogel and Its Application for Sustained Drug Release.

Herein, crack-free photonic crystal templates with enhanced color contrast were first demonstrated by the coassembly of polystyrene (PS) microspheres and graphene oxide (GO). Then, photonic crystal hydrogels (PCHs) with quick responses to temperature and alcohol solution concentration changes were fabricated by photopolymerization of monomers in the gaps of the self-assembled colloidal crystal templates. The structural color of the PCHs changed from yellow to blue within 120 s as the temperature rose from 25 to 40 °C, whereas upon a decrease in temperature from 40 to 25 °C, the structural color changed from blue to yellow. The structural color of the PCHs also shows an obvious response with the concentration of alcohol solution ranging from 40 to 100 wt %. The quick responses of the PCHs' structural color to changes in temperature and alcohol solution concentration are attributed to the temperature sensitivity of poly(N-isopropylacrylamide) and preferential adsorption and swelling of the alcohol solution for the polymer chains. Furthermore, moxifloxacin (Mox) was loaded into PCHs by hydrogel swelling and exhibited sustained released by increasing the temperature. The sustained release process was facilely monitored by observing the corresponding color changes in real time. The rapid and visible response offers the fabricated PCHs great potential application prospects in the semiquantitative analysis of alcohol concentration and intelligent drug delivery.

Mussel-inspired hydrogels as tough, self-adhesive and conductive bioelectronics: a review.

To overcome the wearable sensor's defects and achieve the goal of robust mechanical properties, long-term adhesion, sensitive electrical conductivity, the multifunctional hydrogels were inspired by various mussels on the base of catechol and its analogues. In this review, we review the strategies for improving the mechanical strength, adhesion, conductivity and antibacterial properties of mussel-inspired hydrogels as bioelectronics. Double network structures, nanocomposites, supramolecular block polymers and other strategies were utilized for achieving tough hydrogels to prevent tensile fractures under high deformation. Many mussel-inspired chemistries were incorporated for constructing skin-attachable hydrogel strain sensors and some strategies for controlling the oxidation of catechol were employed to achieve long-term adhesion. In addition, electrolytes, conductive fillers, conductive polymers and their relevant hydrophilic modifications were introduced for fabricating the conductive hydrogel bioelectronics to enhance the conductivity properties. Finally, the challenges and outlooks in this promising field are featured from the perspective of materials chemistry.

Dual-stimuli-responsive porous polymer enzyme reactor for tuning enzymolysis efficiency.

A strategy for preparing a dual-stimuli-responsive porous polymer membrane enzyme reactor (D-PPMER) is described, consisting of poly (styrene-maleic anhydride-N-isopropylacrylamide-acrylate-3',3'-dimethyl-6-nitro-spiro[2H-1-benzopyran-2,2'-indoline]-1'-esterspiropyran ester) [P(S-M-N-SP)] and D-amino acid oxidase. Tunable control via "on/off" 365 nm UV light irradiation and temperature variation was used to change the membrane surface configuration and adjust the enzymolysis efficiency of the D-PPMER. A chiral capillary electrophoresis technique was developed for evaluation of the enzymatic efficiency of D-PPMER with a Zn(II)-dipeptide complex as the chiral selector and D,L-serine as the substrate. Interestingly, the enzymatic kinetic reaction rate of D-PPMER under UV irradiation at 36 °C (9.2 × 10-2 mM·min-1) was 3.2-fold greater than that of the free enzyme (2.9 × 10-2 mM·min-1). This was because upon UV irradiation at high temperature, the P(SP) and P(N) moieties altered from a "stretched" to a "curled" state to encapsulate the enzyme in smaller cavities. The confinement effect of the cavities further improved the enzymatic efficiency of the D-PPMER. This protocol highlights the outstanding potential of smart polymers, enables tunable control over the kinetic rates of stimuli-responsive enzyme reactors, and establishes a platform for adjusting enzymolysis efficiency using two different stimuli.

Non-Close-Packed Particle Arrays Based on Anisotropic Red Blood Cell (RBC) like Particles via Stretching Deformation Method.

Non-close-packed (NCP) particle arrays have potential applications in many fields such as photonics and sensors. However, due to thermodynamic stability, it is still a challenge to produce NCP arrays by the traditional approach. Here, we demonstrated a facile method to fabricate hexagonal close-packed (HCP) arrays with different orientations from that of the Janus particles. After that, the HCP arrays can be easily tuned by stretching deformation of polyethylene film. By tuning the stretching elongations, NCP arrays with five Bravais lattice structures were obtained. Besides, to fabricate the complex structure, these arrays were used as templates to assemble binary particle arrays. Such tunable crystal lattice and binary self-assembly crystal can be useful for fabricating more flexible structures and more open systems.