Fluorescent Polymeric Micelles with Tetraphenylethylene Moieties and Their Application for the Selective Detection of Glucose

Controlling the Fluorescence Performance of AIE Polymers by Controlling the Polymer Microstructure

Aggregation-induced emission (AIE) polymers with expected emission wavelength/color and fluorescence efficiency are valuable in applications. However, most AIE polymers exhibit irregular emission wavelength/color changes compared to the original AIE monomers. Here, we report the synthesis of AIE polymers with unchanged emission wavelength by ring-opening (co)polymerizations of 4-(triphenylethenyl)phenoxymethyloxirane (TPEO) and other epoxides or phthalic anhydride. The chemical structures/physical properties of all (co)polymers were characterized by NMR, SEC, MALDI-TOF, and DSC. The co-polyether microstructures were revealed by calculating the reactivity ratios and visualized by Monte Carlo simulation. The photoluminescence quantum yields of all the (co)polymers were determined in the solid state. We systematically correlated the fluorescence performance with molecular weights, crystallinity, monomer compositions, glass transition temperatures, side lengths, and flexibility/rigidity.

Aggregation-induced emission-active micelles: synthesis, characterization, and applications

Aggregation-induced emission (AIE)-active micelles are a type of fluorescent functional materials that exhibit enhanced emissions in the aggregated surfactant state. They have received significant interest due to their excellent fluorescence efficiency in the aggregated state, remarkable processability, and solubility. AIE-active micelles can be designed through the self-assembly of amphipathic AIE luminogens (AIEgens) and the encapsulation of non-emissive amphipathic molecules in AIEgens. Currently, a wide range of AIE-active micelles have been constructed, with a significant increase in research interest in this area. A series of advanced techniques has been used to characterize AIE-active micelles, such as cryogenic-electron microscopy (Cryo-EM) and confocal laser scanning microscopy (CLSM). This review provides an overview of the synthesis, characterization, and applications of AIE-active micelles, especially their applications in cell and in vivo imaging, biological and organic compound sensors, anticancer drugs, gene delivery, chemotherapy, photodynamic therapy, and photocatalytic reactions, with a focus on the most recent developments. Based on the synergistic effect of micelles and AIE, it is anticipated that this review will guide the development of innovative and fascinating AIE-active micelle materials with exciting architectures and functions in the future.

Biomedical Applications of polymeric micelles in the treatment of diabetes mellitus: Current success and future approaches

INTRODUCTION

Diabetes mellitus (DM) is the most common metabolic disease and multifactorial, harming patients worldwide. Extensive research has been carried out in the search for novel drug delivery systems offering reliable control of glucose levels for diabetics, aiming at efficient management of DM.

AREAS COVERED

Polymeric micelles (PMs) as smart drug delivery nanocarriers are discussed, focusing on oral drug delivery applications for the management of hyperglycemia. The most recent approaches used for the preparation of smart PMs employ molecular features of amphiphilic block copolymers (ABCs), such as stimulus sensitivity, ligand conjugation, and as a more specific example the ability to inhibit islet amyloidosis.

EXPERT OPINION

PMs provide a unique platform for self-regulated or spatiotemporal drug delivery, mimicking the working mode of pancreatic islets to maintain glucose homeostasis for prolonged periods. This unique characteristic is achieved by tailoring the functional chemistry of ABCs considering the physicochemical traits of PMs, including sensing capabilities, hydrophobicity, etc. In addition, the application of ABCs for the inhibition of conformational changes in islet amyloid polypeptide garnered attention as one of the root causes of DM. However, research in this field is limited and further studies at the clinical level are required.

AIE active polymers for biological applications

The discovery of aggregation-induced emission (AIE) phenomenon, significantly altered the understanding of the scientific world about the luminophore aggregation. Polymers with AIE features have recently emerged as promising materials with wide range of applications in optoelectronics devices, chemosensors, bioimaging, cancer theranostics and drug delivery. By introducing the AIE active molecule into the polymer structure, novel materials encompassing the characteristics properties of both the functional materials such as excellent brightness, versatile structure modification, high biocompatibility, exceptional stability and facile processability are achieved. This chapter presents the advances in synthetic design as well as potential biological applications of AIE active polymers, beginning with a brief introduction to the AIE phenomenon. The versatile synthetic route, easier functionalization, and light up feature of the AIE active polymers offer direct visualization of the physiological processes within or outside the living organisms. This chapter also precisely describes the photodynamic therapy/photothermal therapy (PDT/PTT) with up-to-date advancement of AIE active polymer and their emerging applications in biomedical field. The AIE active Photosensitizers (PSs) are much more efficient in singlet oxygen (¹O₂) production than their small molecule AIE active PSs due to their enhanced inter system crossing (ISC) process and improved light-harvesting ability. Additionally, the present chapter aims to focus on all recent AIE active polymers for drug screening and drug delivery. The AIE active polymer often shows decent drug loading capacity, high stability and good biocompatibility comprising image guided drug monitoring features. Lastly, the concluding discussion reveals the future prospective of the AIE active polymers.

Converse transitions between the micelles and the vesicles of pyrrolidone-based AIE amphiphilic copolymers in polar and apolar solvents

Herein, a new family of aggregation-induced emission (AIE) amphiphilic copolymers, named poly(N-(2-methacryloyloxyethyl)pyrrolidone)-b-poly(lauryl methacrylate-co-1-ethenyl-4-(1,2,2-triphenylethenyl)benzene), PNMP_x-b-P(LMA_y-co-TPE_z), was developed by the reversible addition–fragmentation chain transfer (RAFT) polymerization method. The polymerization degree x of the NMP segment was kept constant at 35, whereas that of the LMA segment ranged from 9 to 55 with the polymerization degree ratio y/z of the LMA and TPE segments being around 9. As a result, the PNMP_x-b-P(LMA_y-co-TPE_z) copolymer gradually transformed from being water soluble to oil soluble with an increase in the length of the P(LMA_y-co-TPE_z) segment. Moreover, these copolymers could form self-organized normal and reverse assemblies in both water and n-dodecane. Various morphologies, including spherical micelles, worm-like micelles and vesicles, were confirmed by the transmission electron microscopy (TEM) observation. Specifically, the micelle-to-vesicle transition via worm-like micelles occurred in the aqueous solution upon increasing the length of the P(LMA_y-co-TPE_z) segment, whereas the reverse transition occurred in n-dodecane. Because of the presence of the AIE-active TPE segment, both the aqueous and the n-dodecane solutions of PNMP_x-b-P(LMA_y-co-TPE_z) were highly luminescent, and their fluorescence quantum yields significantly depended on the polarity of the solvent and the morphology of the assemblies. Due to the strong luminescence properties of PNMP_x-b-P(LMA_y-co-TPE_z) assemblies, these AIE-active amphiphilic copolymers acted as excellent bioimaging probes with high efficiency.

A series of AIE-active amphiphilic copolymers, PNMP_x-b-P(LMA_y-co-TPE_z), were developed as bioimaging probes. Converse transitions from spherical micelles to vesicles via wormlike micelles of them in water and n-dodecane were happened, respectively.

Selectively light-up hydrogen peroxide in hypoxic cancer cells with a novel fluorescent probe

A novel fluorescent turn-on probe (HCyHP) was developed in a simple two-step synthesis for monitoring of exogenous and endogenous H2O2 levels in biological samples and hypoxic cancer diagnosis.

Evaporation-Induced Biomolecule Detection on Versatile Superhydrophilic Patterned Surfaces: Glucose and DNA Assay

We introduce a droplet-based biomolecular detection platform using robust, versatile, and low-cost superhydrophilic patterned superhydrophobic surfaces. Benefitting from confinement and evaporation-induced shrinkage of droplets on wetted patterns, we show enrichment-based biomolecular detection using very low sample volumes. First, we developed a glucose assay using fluorescent polydopamine (PDA) based on enhancement of PDA emission by hydrogen peroxide (H₂O₂) produced in enzyme-mediated glucose oxidation reaction. Incubation in evaporating droplets resulted in brighter fluorescence compared to that in bulk solutions. Droplet assay was highly sensitive toward increasing glucose concentration while that in milliliter-volume solutions resulted in no fluorescence enhancement at similar time scales. This is due to droplet evaporation that increased the reaction rate by causing enrichment of PDA and glucose/glucose oxidase as well as increased concentration of H₂O₂ generated in shrinking droplet. Second, we chemically functionalized wetted patterns with single-stranded DNA and developed fluorescence-based DNA detection to demonstrate the adaptability of the patterned surfaces for a different class of assay. We achieved detection of glucose and DNA with concentration down to 130 μM and 200 fM, respectively. Patterned superhydrophobic surfaces with their simple production, sensitive response, and versatility present potential for bioanalysis from low sample volumes.

Tetraphenylethylene-Based AIE-Active Probes for Sensing Applications

This Review provides a comprehensive analysis of recent development in the field of aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) luminophores and their applications in biomolecular science. It begins with a discussion of the diverse range of structural motifs that have found particular applications in sensing, and demonstrates that TPE structures and their derivatives have been used for a diverse range of analytes such as such as H⁺, anions, cations, heavy metals, organic volatiles, and toxic gases. Advances are discussed in depth where TPE is utilized as a mechanoluminescent material in bioinspired receptor units with specificity for analytes for such as glucose or RNA. The rapid advances in sensor research make this summary of recent developments in AIE-active TPE luminophores timely, in order to disseminate the advantages of these materials for sensing of analytes in solution, as well as the importance of solid and aggregated states in controlling sensing behavior.

Highly efficient luminescent side-chain polymers with short-spacer attached tetraphenylethylene AIEgens via RAFT polymerization capable of naked eye explosive detection

The fluorescence quantum yield of side-chain AIE polymers was remarkably promoted just by shortening the linking spacer.

Tunable emission of a tetraphenylethylene copolymer via polymer matrix assisted and aggregation-induced emission

A novel polyacrylamide copolymer possessing tetraphenylethylene AIEgens was synthesized, exhibiting tunable fluorescence emission. Hydrogen bonding in the copolymer matrix played an important role in providing a rigid environment and blocking the non-radiative pathway thereby strengthening fluorescence emission.

An AIE-active fluorescence turn-on bioprobe mediated by hydrogen-bonding interaction for highly sensitive detection of hydrogen peroxide and glucose

An AIE-active “turn-on” bioprobe is designed for hydrogen peroxide detection based on an imine-functionalized tetraphenylethene derivative.

Synthesis of amphiphilic fluorescent PEGylated AIE nanoparticles via RAFT polymerization and their cell imaging applications

This work reports the fabrication of amphiphilic TPEV–PEG fluorescent copolymers via RAFT polymerization of polymerizable AIE and PEGMA with promising applications for bioimaging.

Supramolecular assembly-induced yellow emission of 9,10-distyrylanthracene bridged bis(pillar[5]arene)s

Newly synthesized DSA-bridged bis(pillar[5]arene)s with AIE properties form linear supramolecular polymers upon binding to a neutral guest linker, exhibiting supramolecular assembly-induced yellow fluorescence emission.

Aggregation-induced emission block copolymers based on ring-opening metathesis polymerization

AIE amphiphilic block copolymers were developed from ROMP for the first time. By self-assembly in selective solvents, water soluble fluorescent nano-objects were prepared with varied structures including micelles and vesicles.

AIE macromolecules: syntheses, structures and functionalities

A comprehensive review of macromolecules with aggregation-induced emission attributes is presented, covering the frontiers of syntheses, structures, functionalities and applications.