Rhodamine 6G-Anionic Surfactant System Modified by Triton X-100 for Fluorescence Determination of Albumin

The influence of sodium hexadecyl sulfate on the nature of the fluorescence spectra of rhodamine 6G in an aqueous solution and a solution of nonionic Triton X-100 was investigated. The change in the nature of the emission spectra is explained by the formation of hydrophobic stoichiometric and sub-stoichiometric reagent-surfactant associates. Stabilization of the colloid-chemical state and reduction of the total turbidity of rhodamine 6G-anionic surfactant associate solutions with the addition of nonionic surfactant as a modifier were registered. The method of modification of the rhodamine 6G-sodium hexadecyl sulfate system with a nonionic surfactant was used in the development of conditions for the fluorescence determination of protein substances in physiological solutions. The concentration conditions for the use of the modified reagent system rhodamine 6G-anionic surfactant-nonionic surfactant for the fluorescence determination of albumin in urine were optimized.

Enzymatic noncovalent synthesis of peptide assemblies generates multimolecular crowding in cells for biomedical applications

Enzymatic noncovalent synthesis enables the spatiotemporal control of multimolecular crowding in cells, thus offering a unique opportunity for modulating cellular functions. This article introduces some representative enzymes and molecular building blocks for generating peptide assemblies as multimolecular crowding in cells, highlights the relevant biomedical applications, such as anticancer therapy, molecular imaging, trafficking proteins, genetic engineering, artificial intracellular filaments, cell morphogenesis, and antibacterial, and briefly discusses the promises of ENS as a multistep molecular process in biology and medicine.

Enzymatic Noncovalent Synthesis

Enzymatic reactions and noncovalent (i.e., supramolecular) interactions are two fundamental nongenetic attributes of life. Enzymatic noncovalent synthesis (ENS) refers to a process where enzymatic reactions control intermolecular noncovalent interactions for spatial organization of higher-order molecular assemblies that exhibit emergent properties and functions. Like enzymatic covalent synthesis (ECS), in which an enzyme catalyzes the formation of covalent bonds to generate individual molecules, ENS is a unifying theme for understanding the functions, morphologies, and locations of molecular ensembles in cellular environments. This review intends to provide a summary of the works of ENS within the past decade and emphasize ENS for functions. After comparing ECS and ENS, we describe a few representative examples where nature uses ENS, as a rule of life, to create the ensembles of biomacromolecules for emergent properties/functions in a myriad of cellular processes. Then, we focus on ENS of man-made (synthetic) molecules in cell-free conditions, classified by the types of enzymes. After that, we introduce the exploration of ENS of man-made molecules in the context of cells by discussing intercellular, peri/intracellular, and subcellular ENS for cell morphogenesis, molecular imaging, cancer therapy, and other applications. Finally, we provide a perspective on the promises of ENS for developing molecular assemblies/processes for functions. This review aims to be an updated introduction for researchers who are interested in exploring noncovalent synthesis for developing molecular science and technologies to address societal needs.

Surfactant Aggregates Encapsulating and Modulating: An Effective Way to Generate Selective and Discriminative Fluorescent Sensors

The heterogeneous structure and dynamic balancing nature of surfactant aggregates make them attractive in developing fluorescent sensors. They can provide a number of advantages, e.g., enhanced fluorescence stability and quantum yield, detection capability in aqueous solutions, and easy operation. Thus, various strategies have been used to construct surfactant aggregate-based fluorescent sensors. Surfactant aggregates play various roles in different strategies and realize multiple sensing behaviors. Many new functions have been discovered for surfactant aggregates in constructing fluorescent sensors. In this feature article, we briefly summarize the development of surfactant aggregate-based fluorescent sensors and their applications in three different types of sensing: selective sensing, multiple analyte sensing, and cross-reactive sensing. For each type of sensing, the design strategies and the roles of surfactant aggregates are particularly introduced. An understanding of these aspects will help to expand the applications of surfactant assemblies in the sensing field.

Supramolecular Self-Assembly of Perylene Bisimide Derivatives Assisted by Various Groups

Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetraone, namely, perylene bisimides (PBIs), belong to n-type organic semiconductors and possess potential applications in optoelectronic devices. The properties/performance of fabricated nanostructures/devices could be greatly influenced by both molecular structures of PBI building blocks and corresponding arrangement in assembled nanostructures. Many efforts have been made to modify the PBI core and then investigate the nanostructures and properties. However, it is still a great challenge to comprehensively understand the influence of molecular structures on the intermolecular interactions, the self-assembled structures, and the resulting performance. In the present contribution, we mainly summarize recent research aspects on supramolecular assembly behaviors of PBI derivatives assisted by various functional groups. First, a short introduction is given about basic molecular structure, properties, and self-assembly of PBI derivatives. Then, we mainly discuss the modulation of self-assembly of PBIs via introducing various functional groups (flexible or nonflexible chains, and biomolecules especially amino-acid-based groups). After that, the assembly of PBI derivatives from out-of-equilibrium states is described. Finally, a perspective is provided on the design of novel PBI derivatives and the fabrication of unique nanostructures with superior properties.

A ratiometric fluorescence assay for acetylcholinesterase activity and inhibitor screening based on supramolecular assembly induced monomer-excimer emission transition of a perylene probe

A ratiometric fluorescence assay for acetylcholinesterase activity is established, which is based on controlled perylene probe assembly and monomer-excimer transition. In a buffer solution, a perylene probe with two negatively charged groups (PDI-DHA) mainly exists in monomeric form. In the presence of cationic lauroylcholine and lauric acid, PDI-DHA can form supramolecular assemblies and the perylene excimer emission can be observed. AChE can catalyze the hydrolysis of lauroylcholine to anionic lauric acid and choline. The hydrolysis process can trigger the breakdown of the supramolecular assemblies. The perylene excimer recovers to the monomeric form because of the de-aggregation of the probe. The excimer-monomer transition can be detected, and a ratiometric fluorescence assay for AChE activity and inhibitor screening is therefore established.

A joint experimental and theoretical study on the electro-optical properties of 1,6- and 1,7-fluorenyl disubstituted perylene diimide isomers

The electronic and optical properties of fluorenyl functionalized perylene diimides are influenced by the substituent position on the perylene core.