A new application of papain: As a peroxidase-like catalyst for fluorometric detection of uric acid.

Papain, as a classical cysteine protease, has been widely used in the food, pharmaceutical, chemical, and cosmetic fields. However, there are few information about the peroxidase-like activity of papain catalyzed substrate to produce fluorescence. In this study, we found that papain can catalyze HO to convert o-phenylenediamine (OPD), and generate fluorescence emission at 550 nm under 430 nm excitation.

A Simple, Rapid, Fluorometric Assay for Dopamine by In Situ Reaction of Boronic Acids and -Diol.

An efficient, sensitive, and low-cost method has been developed for turn-on fluorescence sensing of dopamine (DA). The method relies on the rapid reaction of DA and 3-Hydroxyphenylboronic acid (3-HPBA) via specific recognition between boronic acids and -diol of DA in alkaline solution. The reaction product shows an excitation wavelength of 417 nm and the maximum emission peak at 470 nm.

Study of Bi-directional detection for ascorbic acid and sodium nitrite based on Eu-containing luminescent polyoxometalate.

Eu-containing polyoxometalate KEu(SiMoWO)·28HO (Eu-SiMoW) owns the stimu-chromic and photoluminescence properties. An ingenious test of ascorbic acid (AA) and sodium nitrite (NaNO) was carried out based on the dual properties of Eu-SiMoW in solutions. First, the redox reaction of Eu-SiMoW and AA generated the blue reduced Eu-SiMoW, accompanied by fluorescence quenching; then the redox reaction of the reduced Eu-SiMoW and NaNO made Eu-SiMoW back to its original pale yellow state with red luminescence.

Fabrication of white luminescence composite films containing Dy-polyoxometalate and the study of their luminescence switching behaviors.

White luminescence composite films containing Dy-polyoxometalate (Dy-POM) were firstly constructed by a layer-by-layer assembly method for the realization of electrically controlled luminescence switching. Additionally, blue-white luminescence could be switched by the choice of POM structural types and control of the concentration ratio of POM/Dy-POM in solution and composite films.

Heteropoly acids triggered self-assembly of cationic peptides into photo- and electro-chromic gels.

A series of cationic peptides with alternating lysines and hydrophobic residues were designed and synthesized. These kinds of short peptides with protonated lysines can complex with anionic heteropoly acids (HPAs) to form a stable gel in water/ethanol mixed solution. Circular dichroism spectroscopy showed that the short peptides adopted a mixed conformation (β-sheet and random-coil) within the gel matrix.

First Orange Fluorescence Composite Film Based on Sm-Substituted Tungstophosphate and Its Electrofluorochromic Performance.

We chose a Sm-containing sandwich-type tungstophosphate K3Cs8[Sm(PW11O39)2]·10H2O (SmPW11) as a molecular dyad, which contains photoluminescence and electrochromism components in a skeletal structure, and investigated its electrofluorochromic performance both in solution and in composite films. First, the electrochemical activity and luminescence property of SmPW11 were studied in different pH solutions to determine the optimal pH solution medium; and then, the electrofluorochromic performance of SmPW11 was investigated under the optimized pH solution medium. Subsequently, the composite films containing SmPW11 were prepared on quartz substrates and conductive ITO substrates through a layer-by-layer (LbL) assembly method, using PDDA and PEI as molecular linkers.

An effective combination of electrodeposition and layer-by-layer assembly to construct composite films with luminescence switching behavior.

This article presents a combination strategy of electrodeposition and a layer-by-layer assembly to fabricate functional composite films with luminescence switching behavior. Firstly, a novel green luminescence film consisting of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HOPTS) was first obtained on ITO by a facile electrodeposition method. Then, the multilayer films containing different layers of tungstophosphate K12.

Force field development for organic molecules: modifying dihedral and 1-n pair interaction parameters.

We comprehensively illustrate a general process of fitting all-atom molecular mechanics force field (FF) parameters based on quantum mechanical calculations and experimental thermodynamic data. For common organic molecules with free dihedral rotations, this FF format is comprised of the usual bond stretching, angle bending, proper and improper dihedral rotation, and 1-4 scaling pair interactions. An extra format of 1-n scaling pair interaction is introduced when a specific intramolecular rotation is strongly hindered.