Ultrafast Preparation of AIE-Active Fluorescent Organic Nanoparticles via a “One-Pot” Microwave-Assisted Kabachnik-Fields Reaction

Recent Advances on Fabrication of Polymeric Composites Based on Multicomponent Reactions for Bioimaging and Environmental Pollutant Removal

As the core of polymer chemistry, manufacture of functional polymers is one of research hotspots over the past several decades. Various polymers are developed for diverse applications due to their tunable structures and unique properties. However, traditional step-by-step preparation strategies inevitably involve some problems, such as separation, purification, and time-consuming. The multicomponent reactions (MCRs) are emerging as environmentally benign synthetic strategies to construct multifunctional polymers or composites with pendant groups and designed structures because of their features, such as efficient, fast, green, and atom economy. This mini review summarizes the latest advances about fabrication of multifunctional fluorescent polymers or adsorptive polymeric composites through different MCRs, including Kabachnik-Fields reaction, Biginelli reaction, mercaptoacetic acid locking imine reaction, Debus-Radziszewski reaction, and Mannich reaction. The potential applications of these polymeric composites in biomedical and environmental remediation are also highlighted. It is expected that this mini-review will promote the development preparation and applications of functional polymers through MCRs.

Amphiphilic Polymer-Mediated Aggregation-Induced Emission Nanoparticles for Highly Sensitive Organophosphorus Pesticide Biosensing

Biosensing applications require signal reporters to be sufficiently stable and biosafe as well as highly efficient. Aggregation-induced emission (AIE) nanoparticles have proven to be capable of cell-imaging and cancer therapy; however, realizing sensitive detection of biomolecules remains a great challenge because of their instability, biotoxicity, and lack of modifiable functional groups. Herein, we report a self-assembling strategy to fabricate AIE nanoparticles (PTDNPs) through the dispersion of amphiphilic polymers (PTDs) in phosphate-buffered saline. The PTDs were prepared through radical copolymerization of N-(1,2,2-triphenylvinyl)-4-acetylaniline and dimethyl diallyl ammonium chloride. We found that the particle size, morphology, functional groups, and fluorescence property of PTDNPs can be fine-tuned. Further, PTDNPs-0.10 were chosen as signal reporters to detect organophosphorus pesticides (OPs) with the aid of gold nanoparticles. Their sensing performance on OPs is superior to that using C-dot/quantum dot/rhodamine B as the signal reporter. This study not only provides new possibilities to fabricate novel AIE nanoparticles with exceptional properties, but also facilitates the AIE nanoparticle's application for target analyte biosensing.

Surface grafting of rare-earth ions doped hydroxyapatite nanorods (HAp:Ln(Eu/Tb)) with hydrophilic copolymers based on ligand exchange reaction: Biological imaging and cancer treatment

Rare-earth ions doped hydroxyapatite nanoparticles (HAp:Ln NPs) have demonstrated to be very promising candidates for biological imaging applications owing to their small size and chemical compositions similar to bone. However, these HAp:Ln NPs with controllable size and morphology should be prepared under hydrothermal treatment with hydrophobic molecules as the protective layers. The hydrophobic nature of these luminescent HAp:Ln NPs largely impeded their applications in biomedical fields. In this study, a novel and effective strategy has been developed for the surface modification of HAp:Ln nanorods through the combination of surface ligand exchange reaction and reversible-addition fragmentation chain transfer (RAFT) polymerization using 2-methacryloyloxyethyl phosphorylcholine (MPC) and itaconic acid (IA) as the monomers. Herein, a small molecule adenosine 5'-monophosphate disodium salt (AMP) that contains a phosphate group and two hydroxyl groups was used to displace the hydrophobic oleic acid on pristine HAp NPs through surface ligand exchange reaction owing to its stronger interaction with HAp NPs. On the other hand, the MPC and IA were introduced on HAp NPs through RAFT polymerization after the chain transfer agent was immobilized on the HAp NPs through the esterification reaction. The poly(IA-MPC) could not only endow the high water dispersibility but also be used for loading anticancer agent cisplatin (CDDP) through coordination interaction. To evaluate their potential biomedical applications, the cell uptake behavior, drug loading capacity and release behavior as well as cell viability of HAp:Ln-AMP-poly(IA-MPC) polymeric composites were examined. We demonstrated that the method developed in this work is very effective for introduction of functional polymers onto HAp:Ln nanorods. The HAp:Ln-AMP-poly(IA-MPC) composites are promising for cell imaging and controlled delivery of CDDP.

Self-Assembled α-Cyanostilbenes for Advanced Functional Materials

In the specific context of condensed media, the significant and increasing recent interest in the α-cyanostilbene (CS) motif [ArCHC(CN)Ar] is relevant. These compounds have shown remarkable optical features in addition to interesting electrical properties, and hence they are recognized as very suitable and versatile options for the development of functional materials. This progress report is focused on current and future use of CS structures and molecular assemblies with the aim of exploring and developing for the next generations of functional materials. A critical selection of illustrative materials that contain the CS motif, including relevant subfamilies such as the dicyanodistyrylbenzene and 2,3,3-triphenylacrylonitrile shows how, driven by the self-assembly of CS blocks, a variety of properties, effects, and possibilities for practical applications can be offered to the scientific community, through different rational routes for the elaboration of advanced materials. A survey is provided on the research efforts directed toward promoting the self-assembly of the solid state (polycrystalline solids, thin films, and single crystals), liquid crystals, nanostructures, and gels with multistimuli responsiveness, and applications for sensors, organic light-emitting diodes, organic field effect transistors, organic lasers, solar cells, or bioimaging purposes.

A new strategy for fabrication of water dispersible and biodegradable fluorescent organic nanoparticles with AIE and ESIPT characteristics and their utilization for bioimaging

Fluorescence probes play a crucial role in optical imaging for visualization of complex biological processes. As compared with conventional organic fluorogens, the probes with aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics show significant advantages in high quantum yield at concentrated and aggregated state, large Stokes shift and low cytotoxicity. However, the synthesis of AIE-active fluorescent probes through the ESIPT mechanism has received only very limited attention. On the other hand, the preparation of biodegradable fluorescent probes through the ESIPT mechanism has not been demonstrated thus far. In this work, we reported for the first time that water dispersible and biodegradable fluorescent polymeric nanoparticles with AIE and ESIPT characteristics could be facilely obtained through conjugation of 2,4-Dihydroxybenzophenone based benzophenone azine (BPA) and polyethylene glycol (PEG) using hexamethylene diisocyanate. The final copolymers contained hydrophilic and biocompatible PEG and biodegradable urethane linkage are readily self-assembled into core-shell nanostructures. Moreover, the self-assembled BPA-PEG₂₀₀₀ fluorescent organic nanoparticles (FONs) displayed obvious AIE feature, high water dispersibility, superb biocompatibility, biodegradability and excellent cell dyeing performance. All of the above properties implied that BPA-PEG₂₀₀₀ FONs are promising candidates for a variety of biomedical applications.

Wettability with Aggregation-Induced Emission Luminogens

Aggregation-induced emission luminogens (AIEgens) have become an emerging field since the concept of AIE was proposed in 2001. Recently, AIEgens have attracted considerable attention due to their abnormal non-emissive fluorescent behavior in solution but strongly emissive behavior in the aggregate state. By utilizing the inherent hydrophobicity, AIEgens can be used to monitor the crystal formation and dewetting behavior in the self-assembly process. More importantly, some stimuli-responsive AIE-active surfaces have been successfully fabricated. In this perspective review, we outline the advances of surface wettability of AIEgens and its applications.

Polymerizable aggregation-induced emission dye for preparation of cross-linkable fluorescent nanoprobes with ultra-low critical micelle concentrations

In recent years, aggregation-induced emission (AIE) dyes based fluorescent organic nanoparticles (FONs) have achieved significant progress in various biomedical applications. In this work, we developed a covalent strategy to prepare biocompatible AIE-active dyes based cross-linked copolymers (MPC-POSS-PhE) via controllable reversible addition fragmentation chain transfer (RAFT) polymerization using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC), polymerizable AIE dye (named as PhE) and 8-vinyl polyoctahedral silsesquioxanes (POSS) as monomers. Due to the existence of hydrophilic MPC and hydrophobic PhE, the resultant copolymers will self-assemble into core-shell nanoparticles in aqueous solution with ultra-low critical micelle concentration (CMC). This could effectively overcome the drawbacks of non-crosslinked micelles and show more attractive properties and better performance for biomedical applications. Furthermore, the characterization results and biological assays demonstrated that the final MPC-POSS-PhE FONs show stable aqueous stability, uniform size and morphology, high water dispersity, desirable optical properties and low cytotoxicity. These remarkable properties make the resultant AIE-active nanoprobes great potential for biomedical applications.

Facile Fabrication of AIE-Active Fluorescent Polymeric Nanoparticles with Ultra-Low Critical Micelle Concentration Based on Ce(IV) Redox Polymerization for Biological Imaging Applications

Fluorescent polymeric nanoparticles (FPNs) with aggregation-induced emission (AIE) property have received increasing attention and possess promising biomedical application potential in the recent years. Many efforts have been devoted to the fabrication methodologies of FPNs and significant advance has been achieved. In this contribution, a novel strategy for the fabrication of AIE-active amphiphilic copolymers is reported for the first time based on the Ce(IV) redox polymerization. As an example, ene group containing AIE-active dye (named as Phe-alc) is directly grafted onto a water soluble polymer polyethylene glycol (PEG) in H₂ O/THF system under low temperature. Thus-obtained amphiphilic fluorescent polymers will self-assemble into FPNs with ultra-low critical micelle concentration, ultra-brightness, and great water dispersibility. Biological evaluation results suggest that the PEG-poly(Phe-alc) possess excellent biocompatibility and can be used for tracing their behavior in cells using confocal laser scanning microscope. These features make PEG-poly(Phe-alc) FPNs promising candidates for many biomedical applications, such as cell imaging, drug delivery vehicles, and targeted tracing. More importantly, many other functional groups can also be incorporated into these AIE-active FPNs through the redox polymerization. Therefore, the redox polymerization should be a facile and effective strategy for fabrication of AIE-active FPNs.

Marrying multicomponent reactions and aggregation-induced emission (AIE): new directions for fluorescent nanoprobes

Recent development and progress for fabrication and applications of aggregation-induced emission polymers through multicomponent reactions have been summarized in this review.

Recent progress and development on polymeric nanomaterials for photothermal therapy: a brief overview

This review article summarizes the recent development and progress of polymeric photothermal agents for photothermal therapy and imaging-guided photothermal therapy applications.

Fabrication of water dispersible and biocompatible AIE-active fluorescent polymeric nanoparticles through a “one-pot” Mannich reaction

Biocompatible and water dispersible fluorescent polymeric nanoparticles with an aggregation-induced emission feature were fabricated through a facile “one-pot” Mannich reaction and utilized for biological imaging applications.