Highly Efficient Supramolecular Aggregation-Induced Emission-Active Pseudorotaxane Luminogen for Functional Bioimaging

A water-soluble luminescent tris(2,4,6-trichlorophenyl)methyl radical-carbazole dyad

Organic luminescent radicals are a new class of materials with potential applications not only in light-emitting devices but also in the biochemistry field. New tris(2,4,6-trichlorophenyl)methyl (TTM) radicals with alkoxy-substituted carbazole donors were synthesized and characterized. PEG-substituted carbazole-TTM was found to be water-soluble. The water-soluble TTM radical aqueous solution showed fluorescence at 777 nm and the ability to shorten the longitudinal relaxation time (T1) of water. The concept of water-soluble luminescent radicals is expected to be used to develop a potential fluorescence and MR dual-use imaging moiety.

Seed-Induced Living Two-Dimensional (2D) Supramolecular Polymerization in Water: Implications on Protein Adsorption and Enzyme Inhibition

In biological systems, programmable supramolecular frameworks characterized by coordinated directional non-covalent interactions are widespread. However, only a small number of reports involve pure water-based dynamic supramolecular assembly of artificial π-amphiphiles, primarily due to the formidable challenge of counteracting the strong hydrophobic dominance of the π-surface in water, leading to undesired kinetic traps. This study reveals the pathway complexity in hydrogen-bonding-mediated supramolecular polymerization of an amide-functionalized naphthalene monoimide (NMI) building block with a hydrophilic oligo-oxyethylene (OE) wedge. O-NMI-2 initially produced entropically driven, collapsed spherical particles in water (Agg-1); however, over a span of 72 h, these metastable Agg-1 gradually transformed into two-dimensional (2D) nanosheets (Agg-2), favoured by both entropy and enthalpy contributions. The intricate self-assembly pathways in O-NMI-2 enable us to explore seed-induced living supramolecular polymerization (LSP) in water for controlled synthesis of monolayered 2D assemblies. Furthermore, we demonstrated the nonspecific surface adsorption of a model enzyme, serine protease α-Chymotrypsin (α-ChT), and consequently the enzyme activity, which could be regulated by controlling the morphological transformation of O-NMI-2 from Agg-1 to Agg-2. We delve into the thermodynamic aspects of such shape-dependent protein-surface interactions and unravel the impact of seed-induced LSP on temporally controlling the catalytic activity of α-ChT.

Pillar[5]arene-based supramolecular pseudorotaxane polymer material for ultra-sensitive detection of Fe3+ and F. RSC Adv 2023;13:12270-12275. [PMID: 37091614 PMCID: PMC10113919 DOI: 10.1039/d3ra00997a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Recent advancements in ultra-sensitive detection, particularly the Aggregation Induced Emission (AIE) materials, have demonstrated a promising detection method due to their low cost, real-time detection, and simplicity of operation. Here, coumarin functionalized pillar[5]arene (P5C) and bis-bromohexyl pillar[5]arene (DP5) were successfully combined to create a linear AIE supramolecular pseudorotaxane polymer (PCDP-G). The use of PCDP-G as a supramolecular AIE polymer material for recyclable ultra-sensitive Fe³⁺ and F^- detection is an interesting application of the materials. According to measurements, the low detection limits of PCDP-G for Fe³⁺ and F^- are 4.16 × 10^-10 M and 6.8 × 10^-10 M, respectively. The PCDP-G is also a very effective logic gate and a material for luminous displays.

Pathway-Controlled Aqueous Supramolecular Polymerization via Solvent-Dependent Chain Conformation Effects

Solute-solvent interactions play a critical role in multiple fields, including biology, materials science, and (physical) organic, polymer, and supramolecular chemistry. Within the growing field of supramolecular polymer science, these interactions have been recognized as an important driving force for (entropically driven) intermolecular association, particularly in aqueous media. However, to date, solute-solvent effects remain poorly understood in the context of complex self-assembly energy landscapes and pathway complexity. Herein, we unravel the role of solute-solvent interactions in controlling chain conformation effects, allowing energy landscape modulation and pathway selection in aqueous supramolecular polymerization. To this end, we have designed a series of oligo(phenylene ethynylene) (OPE)-based bolaamphiphilic Pt(II) complexes OPE2-4 bearing solubilizing triethylene glycol (TEG) chains of equal length on both molecule ends, but a different size of the hydrophobic aromatic scaffold. Strikingly, detailed self-assembly studies in aqueous media disclose a different tendency of the TEG chains to fold back and enwrap the hydrophobic molecular component depending on both the size of the core and the volume fraction of the co-solvent (THF). The relatively small hydrophobic component of OPE2 can be readily shielded by the TEG chains, leading to only one aggregation pathway. In contrast, the decreased capability of the TEG chains to effectively shield larger hydrophobic cores (OPE3 and OPE4) enables different types of solvent quality-dependent conformations (extended, partly back-folded and back-folded), which in turn induce various controllable aggregation pathways with distinct morphologies and mechanisms. Our results shed light on previously underappreciated solvent-dependent chain conformation effects and their role in governing pathway complexity in aqueous media.

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.

Multicharged cyclodextrin supramolecular assemblies

Multicharged cyclodextrin (CD) supramolecular assemblies, including those based on positively/negatively charged modified mono-6-deoxy-CDs, per-6-deoxy-CDs, and random 2,3,6-deoxy-CDs, as well as parent CDs binding positively/negatively charged guests, have been extensively applied in chemistry, materials science, medicine, biological science, catalysis, and other fields. In this review, we primarily focus on summarizing the recent advances in positively/negatively charged CDs and parent CDs encapsulating positively/negatively charged guests, especially the construction process of supramolecular assemblies and their applications. Compared with uncharged CDs, multicharged CDs display remarkably high antiviral and antibacterial activity as well as efficient protein fibrosis inhibition. Meanwhile, charged CDs can interact with oppositely charged dyes, drugs, polymers, and biomacromolecules to achieve effective encapsulation and aggregation. Consequently, multicharged CD supramolecular assemblies show great advantages in improving drug-delivery efficiency, the luminescence properties of materials, molecular recognition and imaging, and the toughness of supramolecular hydrogels, in addition to enabling the construction of multistimuli-responsive assemblies. These features are anticipated to not only promote the development of CD-based supramolecular chemistry but also contribute to the rapid exploitation of these assemblies in diverse interdisciplinary applications.

Progress on Exploring the Luminescent Properties of Organic Molecular Aggregates by Multiscale Modeling

Luminescent molecular aggregates have attracted worldwide attention because of their potential applications in many fields. The luminescent properties of organic aggregates are complicated and highly morphology-dependent, unraveling the intrinsic mechanism behind is urgent. This review summarizes recent works on investigating the structure-property relationships of organic molecular aggregates at different environments, including crystal, cocrystal, amorphous aggregate, and doped systems by multiscale modeling protocol. We aim to explore the influence of intermolecular non-covalent interactions on molecular packing and their photophysical properties and then pave the effective way to design, synthesize, and develop advanced organic luminescent materials.

Theoretical Study of Macrocyclic Host Molecules: From Supramolecular Recognition to Self-Assembly

Supramolecular chemistry focuses on molecular recognition and self-assembly of various building blocks through weak non-covalent interactions, including anion-π, hydrogen bond (HB), hydrophobic interactions, van der Waals (vdW) interactions, etc, which...

Recent Advances in Aggregation-Induced Emission Active Materials for Sensing of Biologically Important Molecules and Drug Delivery System

The emergence and development of aggregation induced emission (AIE) have attracted worldwide attention due to its unique photophysical phenomenon and for removing the obstacle of aggregation-caused quenching (ACQ) which is the most detrimental process thereby making AIE an important and promising aspect in various fields of fluorescent material, sensing, bioimaging, optoelectronics, drug delivery system, and theranostics. In this review, we have discussed insights and explored recent advances that are being made in AIE active materials and their application in sensing, biological cell imaging, and drug delivery systems, and, furthermore, we explored AIE active fluorescent material as a building block in supramolecular chemistry. Herein, we focus on various AIE active molecules such as tetraphenylethylene, AIE-active polymer, quantum dots, AIE active metal-organic framework and triphenylamine, not only in terms of their synthetic routes but also we outline their applications. Finally, we summarize our view of the construction and application of AIE-active molecules, which thus inspiring young researchers to explore new ideas, innovations, and develop the field of supramolecular chemistry in years to come.

Recent progress and future challenges in the supramolecular polymerization of metal-containing monomers

The self-assembly of discrete molecular entities into functional nanomaterials has become a major research area in the past decades. The library of investigated compounds has diversified significantly, while the field as a whole has matured. The incorporation of metal ions in the molecular design of the (supra-)molecular building blocks greatly expands the potential applications, while also offering a promising approach to control molecular recognition and attractive and/or repulsive intermolecular binding events. Hence, supramolecular polymerization of metal-containing monomers has emerged as a major research focus in the field. In this perspective article, we highlight recent significant advances in supramolecular polymerization of metal-containing monomers and discuss their implications for future research. Additionally, we also outline some major challenges that metallosupramolecular chemists (will) have to face to produce metallosupramolecular polymers (MSPs) with advanced applications and functionalities.

Fluorescence Quenching in J-Aggregates through the Formation of Unusual Metastable Dimers

Molecular aggregation alters the optical properties of a system as fluorescence may be activated or quenched. This is usually described within the well-established framework of H- and J-aggregates. While H-aggregates show nonfluorescent blueshifted absorption bands with respect to the isolated monomer, J-aggregates are fluorescent displaying a redshifted peak. In this publication, we employ a combined approach of experiment and theory to study the complex aggregation features and photophysical properties of diaminodicyanoquinone derivatives, which show unusual and puzzling nonfluorescent redshifted absorption bands upon aggregation. Our theoretical analysis demonstrates that stable aggregates do not account for the experimental observations. Instead, we propose an unprecedented mechanism involving metastable dimeric species formed from stable dimers to generate nonfluorescent J-aggregates. These results represent a novel kind of aggregation-induced optical effect and may have broad implications for the photophysics of dye aggregates.

Polypseudorotaxanes Derived from Tetraphenylethylene: Preparation and Tandem-Activated Aggregation-Induced Emission

Tuning the fluorescence of aggregation-induced emission (AIE)-based materials in a reversible way is essential and a requisite for their applications. The multiple host-guest interactions of polypseudorotaxanes (PPRs) could alter the aggregation state of hydrophobic AIE-based polymeric materials and consequently switch the fluorescence. Herein, tetraphenylethylene (TPE) as a typical AIE molecule has been incorporated into the main chains of the guest polyurethane via a step condensation between poly(ethylene glycol) (PEG)-based dicarbonate and TPE-diamine along with the cleavable disulfide bonds. γ-Cyclodextrins (γ-CDs) can selectively recognize the TPE units at the polyurethane chains to afford a PPR. Hydrophilic PEG segments and γ-CD molecules in the PPR could promote the disaggregation of TPE units, suppressing the fluorescence emission of TPE. To restore the aggregated state and fluorescence of TPE units, tris(2-carboxyethyl)phosphine (TCEP) and α-amylase are sequentially introduced to cleave the disulfide bonds and cut α-1,4 glycosidic bonds of γ-CD, reactivating the AIE behavior of PPR tandemly and accomplishing the reversible cycle of tuning the fluorescence of TPE. The present study provides a tandem way to switch the AIE behavior of polymeric materials reversibly.

Poly(amino acid)s-based star AIEgens for cell uptake with pH-response and chiral difference

Chiral aggregation-induced emission luminogens (AIEgens) are the new-generation chiral sensors that regulate chiral signals from the molecular level to the macroscopic assembly. Expanding applications of chiral AIEgens and in-depth understanding of their chiral recognition in biological systems are meaningful. Herein, two star chiral AIEgens, consisting of tetraphenylethene (TPE) as core and poly(N-acryloyl-L(D) valine) (PLV or PDV) as arms, were precisely synthesized via atom transfer radical polymerization (ATRP) technique and named TPE-PLV and TPE-PDV. They possessed typical AIE characteristics and exhibited an increase in concentration-dependent fluorescence intensity. The two AIEgens were pH-responsive and had strong AIE-related emission in acidic solution. Importantly, AIEgens can enter the living cells by ATP dependent endocytosis, then light them up. The interactions between the AIEgens and living human hepatocarcinoma (HepG2) cells revealed that the internalization process of TPE-PLV and TPE-PDV was both chiral-dependent and pH-responsive. This novel strategy for synthesizing poly(amino acid)s functionalized AIEgens could inspire the development of promising fluorescent materials with chirality.

Coal-Tar Dye-based Coordination Cages and Helicates

A strategy to implement four members of the classic coal-tar dye family, Michler's ketone, methylene blue, rhodamine B, and crystal violet, into [Pd2 L4 ] self-assemblies is introduced. Chromophores were incorporated into bis-monodentate ligands using piperazine linkers that allow to retain the auxochromic dialkyl amine functionalities required for intense colors deep in the visible spectrum. Upon palladium coordination, ligands with pyridine donors form lantern-shaped dinuclear cages while quinoline donors lead to strongly twisted [Pd2 L4 ] helicates in solution. In one case, single crystal X-ray diffraction revealed rearrangement to a [Pd3 L6 ] ring structure in the solid state. For nine examined derivatives, showing colors from yellow to deep violet, CD spectroscopy discloses different degrees of chiral induction by an enantiomerically pure guest. Ion mobility mass spectrometry allows to distinguish two binding modes. Self-assemblies based on this new ligand class promise application in chiroptical recognition, photo-redox catalysis and optical materials.

Recent Advances in Two-Photon AIEgens and Their Application in Biological Systems

Two-photon fluorescence imaging technology has the advantages of high light stability, little light damage, and high spatiotemporal resolution, which make it a powerful biological analysis method. However, due to the high concentration or aggregation state of traditional organic light-emitting molecules, the fluorescence intensity is easily reduced or disappears completely, and is not conducive to optimal application. The concept of aggregation-induced emission (AIE) provides a solution to the problem of aggregation-induced luminescence quenching (ACQ), and realizes the high fluorescence quantum yield of luminescent molecules in the aggregation state. In addition, two-photon absorption properties can readily be improved just by increasing the loading content of AIE fluorogen (AIEgen). Therefore, the design and preparation of two-photon fluorescence probes based on AIEgen to achieve high-efficiency fluorescence imaging in vitro/in vivo has become a major research hotspot. This review aims to summarize representative two-photon AIEgens based on triphenylamine, tetraphenylethene, quinoline, naphthalene and other new structures from the past five years, and discuss their great potential in bioimaging applications.

Recent Progress in 3D Printing of Elastic and High-Strength Hydrogels for the Treatment of Osteochondral and Cartilage Diseases

Despite considerable progress for the regenerative medicine, repair of full-thickness articular cartilage defects and osteochondral interface remains challenging. This low efficiency is largely due to the difficulties in recapitulating the stratified zonal architecture of articular cartilage and engineering complex gradients for bone-soft tissue interface. This has led to increased interest in three-dimensional (3D) printing technologies in the field of musculoskeletal tissue engineering. Printable and biocompatible hydrogels are attractive materials for 3D printing applications because they not only own high tunability and complexity, but also offer favorable biomimetic environments for live cells, such as porous structure, high water content, and bioactive molecule incorporation. However, conventional hydrogels are usually mechanically weak and brittle, which cannot reach the mechanical requirements for repair of articular cartilage defects and osteochondral interface. Therefore, the development of elastic and high-strength hydrogels for 3D printing in the repairment of cartilage defects and osteochondral interface is crucial. In this review, we summarized the recent progress in elastic and high-strength hydrogels for 3D printing and categorized them into six groups, namely ion bonds interactions, nanocomposites integrated in hydrogels, supramolecular guest-host interactions, hydrogen bonds interactions, dynamic covalent bonds interactions, and hydrophobic interactions. These 3D printed elastic and high-strength hydrogels may provide new insights for the treatment of osteochondral and cartilage diseases.

Natural-based Hydrogels: A Journey from Simple to Smart Networks for Medical Examination

Natural hydrogels, due to their unique biological properties, have been used extensively for various medical and clinical examinations that are performed to investigate the signs of disease. Recently, complex-crosslinking strategies improved the mechanical properties and advanced approaches have resulted in the introduction of naturally derived hydrogels that exhibit high biocompatibility, with shape memory and self-healing characteristics. Moreover, the creation of self-assembled natural hydrogels under physiological conditions has provided the opportunity to engineer fine-tuning properties. To highlight recent studies of natural-based hydrogels and their applications for medical investigation, a critical review was undertaken using published papers from the Science Direct database. This review presents different natural-based hydrogels (natural, natural-synthetic hybrid and complex-crosslinked hydrogels), their historical evolution, and recent studies of medical examination applications. The application of natural-based hydrogels in the design and fabrication of biosensors, catheters and medical electrodes, detection of cancer, targeted delivery of imaging compounds (bioimaging) and fabrication of fluorescent bioprobes is summarised here. Without doubt, in future, more useful and practical concepts will be derived to identify natural-based hydrogels for a wide range of clinical examination applications.

Fluorescent nanoparticles with ultralow chromophore loading for long-term tumor-targeted imaging

Recently, organic dyes with aggregation-induced emission (AIE) have attracted much attention in bioimaging and diagnostics. Relatively, the application of traditional dyes has diminished because of aggregation-caused quenching (ACQ). In this work, we compare the imaging ability of nanoparticle formulations of these two kinds of dyes. Boron dipyrromethene (BODIPY) was chosen as a representative of the ACQ dyes, and an aggregation-induced emission (AIE) dye BPMT was used for comparison. BODIPY and BPMT were entrapped into PEG_5k-PLA_10k to form BODIPY-loaded NPs (BNPs) and BPMT-loaded NPs (ANPs), respectively. In vivo and ex vivo imaging demonstrated that BNP1 with ultralow BODIPY load (0.07%) can effectively accumulate in tumor tissues and enable long-term noninvasive imaging. In contrast, ANP4 with high BPMT load (1.6%) has poor bioimaging ability. In general, our work has certain reference significance for the application of ACQ dyes and AIEgens in bioimaging, diagnostics, and theranostics. STATEMENT OF SIGNIFICANCE: In this work, Boron dipyrromethene (BODIPY) was chosen as a representative of ACQ dyes. As a control, (Z)-2-(4'-(9H-carbazol-9-yl)-[1,1'-biphenyl]-4-yl)-3-(7-(4-(bis(4methoxyphenyl)amino) phenyl) benzo[c] [1,2,5] thiadiazol-4-yl) acrylonitrile (BPMT) was selected as an aggregation-induced emission (AIE) dye. BODIPY and BPMT was entrapped into PEG5k-PLA10k to form BODIPY-loaded NPs (BNPs) and BPMT-loaded NPs (ANPs), respectively. In vivo and ex vivo imaging demonstrated that BNP1 with ultralow BODIPY load (0.07%) can effectively accumulate in tumor tissues and realize long-term noninvasive imaging. The weaknesses of ACQ effect can be converted into advantages by skillful use of nanotechnology, which can not only save the cost but also realize high efficiency targeted cancer imaging.

Programmed Self-Assembly of Protein-Coated AIE-Featured Nanoparticles with Dual Imaging and Targeted Therapy to Cancer Cells

Modifying different functional moieties into one platform is a conventional strategy for constructing theranostic systems. However, this strategy usually suffers from the unsatisfied efficiency of each individual function. Herein, a programmed self-assembly strategy is presented to fabricate theranostic nanoparticles, which significantly exhibit a dual-modality imaging function involving fluorescence imaging and magnetic resource imaging (MRI), and an efficient targeted therapy to cancer cells. Fluorescent vesicles are first self-assembled by aggregation-induced emission (AIE)-active molecules. Gd³⁺, serving as an MRI agent, is subsequently bound to the vesicles to provide highly positive charges, which have been realized to be anticancer active. Thereafter, transferrin (Tf) protein is introduced onto the surface of Gd³⁺ coordinated vesicles, shielding the positive charges and making the nanoparticles nontoxic to cells. With the assistance of Tf protein, the constructed nanoparticles are specifically targeted to cancer cells. Moreover, Tf proteins further peel off from nanoparticles in lysosomes due to their charge reversion, resulting in highly positive charges and heavy toxicity of nanoparticles to kill cancer cells. In the nanoparticles, each of the functional components acts as double-sided adhesive tape to glue the next layer, so that the abilities of functional components are not compromised. This strategy holds great potential for theranostic nanomedicine.

Sextuple ratiometric thermometry based on 980-nm-upconverted green fluorescence of Er3+ ions in submicron crystals

980-nm-upconverted 530 and 550 nm Er³⁺ green fluorescence spectra of Er³⁺/Yb³⁺-codoped NaGd(WO₄)₂ submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er³⁺. The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method.

TPE-containing amphiphilic block copolymers: synthesis and application in the detection of nitroaromatic pollutants

Two AIE block copolymers termed P1 and P2 bearing TPE and PEG-based chains were synthesized with moderate molecular weights and narrow PDIs via RAFT polymerization. Both P1 and P2 can be used in the fluorescence detection of nitroaromatic compounds (NACs) and cell images.

Enzyme-responsive polymeric micelles with fluorescence fabricated through aggregation-induced copolymer self-assembly for anticancer drug delivery

The TPE moiety with AIE is employed as functional hydrophobic chain to induce copolymer self-assembly and form polymeric micelle that can show enzyme-responsive drug delivery.

AIE-active fluorescent polymeric nanoparticles about dextran derivative: preparation and bioimaging application

Aggregation-induced emission (AIE), as a special phenomenon of fluorescence, can elegantly overcome the fluorescence quenching caused by common fluorescent materials under high concentration conditions and has attracted interest of researchers in many fields. Particularly AIE-active polymer nanoparticles have been widely utilized in a modern biomedical research. In this work, we prepared a novel kind of AIE-active fluorescent polymeric nanoparticals (Dex-OH-CHO) through a facile esterification between a new hydrophobic AIE-active 1, 8-naphthalimide derivative and the hydrophilic dextran. The structure and optical properties of Dex-OH-CHO were characterized in detail by FTIR, ¹H NMR, XPS, TEM and fluorescence spectra. The results showed that Dex-OH-CHO emitted light-blue fluorescence in aqueous solution with high fluorescent quantum yield (Φ = 24.43%, concentration is 20 μg/mL), low CMC (5 μg/mL), good photostability, high water solubility and well dispersivity. Moreover, good biocompatibility and ideal cell uptake made Dex-OH-CHO had a great application potential in biological imaging.

Aggregation-Induced Dual-Phosphorescence from Organic Molecules for Nondoped Light-Emitting Diodes

Aggregation-induced emission (AIE) is a beneficial strategy for generating highly effective solid-state molecular luminescence without suffering losses in quantum yield. However, the majority of reported AIE-active molecules exhibit only strong fluorescence, which is not ideal for electrical excitation in organic light-emitting diodes (OLEDs). By introducing various substituent groups onto the biscarbazole compound, a series of molecular materials with aggregation-induced phosphorescence (AIP) is designed, which exhibits two distinctly different phosphorescence bands and an absolute solid-state room-temperature phosphorescence quantum yield up to 64%. Taking advantage of the AIE feature, the AIP molecules are fabricated into OLEDs as a homogeneous light-emitting layer, which allows for relatively small efficiency roll-off and shows an external electroluminescence quantum yield of up to 5.8%, more than the theoretical limit for purely fluorescent OLED devices. The design showcases a promising strategy for the production of cost-effective and highly efficient OLED technology.

Pyrene-based prospective biomaterial: In vitro bioimaging, protein binding studies and detection of bilirubin and Fe3

Herein, we have meticulously derived the nanosized fluorescent aggregates from pyrene Schiff base (PS) in DMSO:water (10:90) ratio. The aggregation property of PS molecule was characterized by SEM and TEM measurements, revealed the aggregated particles are in spherical shape with ~3 nm in size. Moreover, aggregates exhibit a high fluorescence quantum yield (48%) which was effectively used for the in vitro bioimaging of two different cancer cells such as A549 and MCF-7 cells in which it exhibiting excellent biocompatibility. Further, it was estimated the capability of twofold acridine orange/ethidium bromide (AO/EB) staining to identify the apoptotic associated changes in cancer cells. Additionally, the aggregates were successfully demonstrated as a luminescent probe for the perceptive biomolecule detection of bilirubin. On the other hand, the PS molecule was successfully utilized for protein binding and metal ion sensing studies. The interaction of bovine serum albumin (BSA) with PS molecule in DMSO was using fluorescence spectroscopic method and nature of interaction was also confirmed through molecular docking analysis. The PS molecule also acts as an excellent sensor for biologically important Fe³⁺ ion with detection limit of 336 nM. Overall, PS molecule can be a prospective material in biological field both in solution as well as aggregated forms.

Efficient Aggregation-Induced Emission Manipulated by Polymer Host Materials

Linear copolymer hosts bearing a number of pillar[5]arene dangling side chains are synthesized for the facile construction of highly emissive supramolecular polymer networks (SPNs) upon noncovalently cross-linking with a series of tetraphenyethylene (TPE)-based tetratopic guests terminated with different functional groups through supramolecular host-guest interactions. An extremely high fluorescence quantum yield (98.22%) of the SPNs materials is obtained in tetrahydrofuran (THF) by fine-tuning the parameters, and meanwhile supramolecular light-harvesting systems based on spherical supramolecular nanoparticles are constructed by interweaving 9,10-distyrylanthracene (DSA) and TPE-based guest molecules of aggregation-induced emission (AIE) with the copolymer hosts in the mixed solvent of THF/H₂ O. The present study not only illustrates the restriction of the intramolecular rotations (RIR)-ruled emission enhancement mechanism regulated particularly by macrocyclic arene-containing copolymer hosts, but also suggests a new self-assembly approach to construct high-performance light-harvesting materials.

A novel bis-component AIE smart gel with high selectivity and sensitivity to detect CN-, Fe3+ and H2PO4. SOFT MATTER 2019;15:6348-6352. [PMID: 31290897 DOI: 10.1039/c9sm01035a]

A novel bis-component AIE-gel TG was facilely constructed from two "easy-to-synthesize" tripodal gelators by a simple host-guest self-assembly process. Interestingly, the TG shows strong aggregation-induced emission (AIE) and could be used for highly efficient and sensitive detection and separation of ions (CN^-, Fe³⁺ and H₂PO₄^-). The LODs (limits of lowest detection) of TG for CN^-, Fe³⁺ and H₂PO₄^- are in the range of 4.93 × 10^-9-7.80 × 10^-8 M. Meanwhile, the xerogel of TG could adsorb and separate Fe³⁺ from aqueous solutions, and the adsorption rate is 96%. In addition, a thin film based on the TG could act as a convenient test kit for the detection of CN^- and Fe³⁺. What is more, the TG-Fe film could not only be used as an erasable secure fluorescent display material, but also as a convenient reversible H₂PO₄^- test kit.

AIE Supramolecular Assembly with FRET Effect for Visualizing Drug Delivery

Here, we constructed a nanostructured pH/redox dual-responsive supramolecular drug carrier with both aggregation-induced emission (AIE) and Forster resonance energy transfer (FRET) effects, which enabled selective drug release and monitoring drug delivery and release processes. Taking the hyperbranched polyamide amine (H-PAMAM) with intrinsic AIE effects as the core, poly(ethylene glycol) (PEG) was bridged on its periphery by dithiodipropionic acid. Then, through the host-guest interaction of PEG and α-cyclodextrin, the supramolecular nanoparticles with AIE effects were constructed to load the anticancer drug doxorubicin (DOX). The supramolecular assembly has sufficiently large DOX loading due to the abundant cavities formed by branched structures. The hyperbranched core H-PAMAM has strong fluorescence, and the dynamic track of drug carriers and the dynamic drug release process can be monitored by the AIE and FRET effects between H-PAMAM and DOX, respectively. Furthermore, the introduction of disulfide bonds and the pH sensitivity of H-PAMAM enable the achievement of rapid selective release of loaded DOX at the tumor while remaining stable under normal physiological conditions. In vitro cytotoxicity indicates that the drug-loaded supramolecular assembly has a good therapeutic effect on cancer. In addition, the H-PAMAM core is different from the traditional AIE functional group, which has no conjugated structure, such as a benzene ring, thereby providing better biocompatibility. This technology will have broad applications as a new drug delivery system.

Rationally introduce AIE into chemosensor: A novel and efficient way to achieving ultrasensitive multi-guest sensing

Recently, ultrasensitive detection and multi-guest sensing have received extensive attention due to their high sensitivity and efficiency. Herein, we report a novel approach to achieve ultrasensitive detection of multi-analyte. This approach is concluded as "rationally introduce Aggregation-Induced Emission (AIE) into chemosensor". According to this approach, by rationally introducing self-assembly moiety, the obtained chemosensor DNS could serve as a novel AIEgen and show strong AIE in DMSO/H₂O (water fraction 80%) binary solution. Interestingly, a simple fluorescent sensor array based on the DNS has been developed. This sensor array could selectively sense Fe³⁺, Al³⁺, H₂PO₄^- and L-Arg in water solution. More importantly, this sensor array shows ultrasensitive detection for Fe³⁺, Al³⁺ and L-Arg. The LODs of the sensor array for Fe³⁺, Al³⁺ and L-Arg are in the range of 3.54×10^-9M to 9.42×10^-9M. Moreover, H₂PO₄^- could realize the reversible detection of Fe³⁺ in the DMSO/H₂O (water fraction 80%) solution. Meanwhile, DNS-based test papers and thin films were prepared, which could serve as test kits for convenient detection Fe³⁺, Al³⁺, and L-Arg in water. In addition, they could also act as efficient erasable fluorescent display materials.

Linear Extrapolation of the Analyte-Specific Light Scattering and Fluorescence Depolarization in Turbid Samples

Anisotropy and depolarization are two interconvertible parameters in fluorescence and light scattering spectroscopy that describe the polarization distribution of emitted and scattered photons generated with linearly polarized excitation light. Whereas anisotropy is more frequently used in fluorescence literature for studying association/dissociation of fluorophore-bearing reagents, depolarization is more popular in the light-scattering literature for investigating the effect of scatterers' geometries and chemical compositions. Presented herein is a combined computational and experimental study of the scattering and fluorescence depolarization enhancement induced by light scattering in turbid samples. The most important finding is that sample light scattering and fluorescence depolarization increases linearly with sample light-scattering extinction. Therefore, one can extrapolate the analyte-specific scattering and fluorescence depolarization through linear curve fitting of the sample light scattering and fluorescence depolarization as a function of the sample concentration or the path length of the sampling cuvettes. An example application of this linear extrapolation method is demonstrated for quantifying the fluorophore-specific fluorescence depolarization and consequently its anisotropy for an aggregation-induced-emission sample. This work should be important for a wide range of macromolecular, supramolecular, and nanoscale fluorescent materials that are often strong light scatterers due to their large sizes.

Enhanced fluorescence quantum yield of syndiotactic side-chain TPE polymers via Rh-catalyzed carbene polymerization: influence of the substitution density and spacer length

The fluorescence quantum yields of the TPE-based C1 polymers also increase with the shortened spacer lengths and further improve by about 20% as compared with the corresponding C2 polyacrylate counterparts.

Disaggregation-induced ESIPT: a novel approach towards development of sensors for hyperglycemic condition

An oxazolonapthoimidazo[1,2-a]pyridine-based fluorescence probe ONIP1 was designed and synthesized via multicomponent reaction. ONIP1 was able to distinguish human serum albumin (HSA) from and glycated-HSA via modulation of AIEE- and ESIPT-based dual channel emission properties.

Anion induced supramolecular polymerization: a novel approach for the ultrasensitive detection and separation of F−

A novel approach for the ultrasensitive detection and separation of F⁻ has been developed. F⁻ could induce a tripodal naphthalimide sensor (TNA) to carry out reversible supramolecular polymerization and lead to strong AIEE.

Fluorescent supramolecular polymers with aggregation induced emission properties

This review summarizes the recent developments in AIE fluorescent supramolecular polymeric materials based on different types of intermolecular noncovalent interactions, and their wide ranging applications as chemical sensors, organic electronic materials, bio-imaging agents and so on.

Supramolecular complexes for nanomedicine

Host-guest interactions studied in supramolecular chemistry have been inspired by interactions between enzymes and substrates. Furthermore, most of the interactions involved in the cells are based on non-covalent bonds between two or more molecules. The common aspects between supramolecular chemistry and medicine have led to the development of a "new" area called "supramolecular medicine", in which non-covalent interactions and self-assembly processes are applied within several medical fields. The object of this Digest is to offer an account of how some macrocyclic hosts (e.g. cucurbiturils, cyclodextrins, pillararenes and calixarenes) are employed in supramolecular medicine creating new supramolecular hydrogels used as biomaterials for human tissue in regenerative medicine, and a diagnostic instrument, in-vitro and in-vivo, for the detection of diseases, as well as for the investigation of cell morphology.