Self-Assembly of Fluorescent Organic Nanoparticles for Iron(III) Sensing and Cellular Imaging

Advancements in delivery systems for dietary polyphenols in enhancing radioprotection effects: challenges and opportunities

Radiotherapy, a widely employed cancer treatment, often triggers diverse inflammatory responses such as radiation enteritis, pulmonary injury, pelvic inflammation, dermatitis, and osteitis. Dietary polyphenols have recently emerged as promising agents for mitigating radiation-induced inflammation. However, their clinical application faced challenges related to variable bioavailability, individual pharmacokinetics, optimal dosing, and limited clinical evidence. Current researches revealed the efficacy of bioactive small molecule polyphenols in addressing radiation-induced inflammation. In this review, along with a comprehensive examination of the etiology and categories of radiation-induced inflammatory conditions, the diversity of polyphenols and elucidating their anti-inflammatory mechanisms are explored. This study emphasizes the recent progresses in delivery systems for dietary polyphenols, aiming to enhance radioprotection effects. The optimized utilization of polyphenols, with a theoretical framework and reference guide, is of paramount relevance. Through diverse delivery mechanisms, the more effective and safer radioprotective strategies become achievable. This endeavor aspires to contribute to breakthroughs in the dietary polyphenols' application, significantly enhancing human health protection during radiotherapy. These comprehensive insights presented here also support (pre)-clinical practices in navigating the complexities of utilizing dietary polyphenols for radioprotection, fostering advancements in the field and improving patient outcomes.

From detection to elimination: iron-based nanomaterials driving tumor imaging and advanced therapies

Iron-based nanomaterials (INMs), due to their particular magnetic property, excellent biocompatibility, and functionality, have been developed into powerful tools in both tumor diagnosis and therapy. We give an overview here on how INMs such as iron oxide nanoparticles, element-doped nanocomposites, and iron-based organic frameworks (MOFs) display versatility for tumor imaging and therapy improvement. In terms of imaging, INMs improve the sensitivity and accuracy of techniques such as magnetic resonance imaging (MRI) and photoacoustic imaging (PAI) and support the development of multimodal imaging platforms. Regarding treatment, INMs play a key role in advanced strategies such as immunotherapy, magnetic hyperthermia, and synergistic combination therapy, which effectively overcome tumor-induced drug resistance and reduce systemic toxicity. The integration of INMs with artificial intelligence (AI) and radiomics further expands its capabilities for precise tumor identification, and treatment optimization, and amplifies treatment monitoring. INMs now link materials science with advanced computing and clinical innovations to enable next-generation cancer diagnostics and therapeutics.

Recent advances in AIEgen-based chemosensors for small molecule detection, with a focus on ion sensing

Since the aggregation-based emission (AIE) phenomenon emerged in 2001, numerous chemical designs have been built around the AIE concept, displaying its utility for diverse applications, including optics, electronics, energy, and biosciences. The present review critically evaluates the broad applicability of AIEgen-based chemical models towards sensing small analytes and the structural design strategies adjusting the mode of action reported since the last decade. Various AIEgen models have been discussed, providing qualitative and quantitative estimation of cationic metal ions and anionic species, as well as biomolecular, cellular, and organelle-specific probes. A systematic overview of the reported structural design and the underlying working mode will pave the way for designing and developing the next generation of AIEgens for specific applications.

Phenolate-thiazole based reversible "turn-on" chemosensor for the selective detection of carbonate anion: X-ray crystallography, DFT/TDFT, and cell study

A new phenolate-thiazole derivative (L) has been synthesized and structurally characterized.The chemo-sensing activity of L is detected by the naked eye for the aqueous carbonate anion in the pH range of 4 to 8. The selective 'turn-on' fluorescence occurs through the formation of a stable intermediate L∙CO32-(1) following the PET mechanism. The limit of detection (LOD) is found 0.18 µM based on the absorbance-based assay.The quinonoid form of bromophenol unit binds strongly with CO32- through thiazole nitrogen and hydrazinic nitrogen. Further, the selective holding of CO32- anion over other planar tetranuclear anions (e.g., SO32-, NO3-) happens with several intra and intermolecular hydrogen bonds as envisaged by the DFT/TDFT study. The formation mechanism of L∙CO32- is proposed based on experimental and theoretical studies. The biological experiments (MTT and cell imaging)reveal the non-cytotoxicity nature of L and the biocompatible uptake of L mostly in the cytoplasm at physiological pH.

Metal Ion Responsive Luminescent Bio-Templated Co-Assemblies: Label-Free Detection of Multi-Metal Ions in Aqueous Media

Recently, anionic bio-templates have emerged as promising platforms for designing dynamic and stimuli-responsive chromophoric assemblies capable of light harvesting in aqueous media thereby mimicking natural photosynthesis. Here, we present multi-metal ion-responsive luminescent co-assemblies between cationic pyrene-imidazolium amphiphile and anionic bio-templates (ATP, heparin, and DNA) in aqueous media. The anionic bio-templates enhance Förster resonance energy transfer (FRET) in the co-assemblies, with pyrene serving as an excellent donor for generating tunable multi-luminescent materials with embedded acceptor dyes. However, a significant loss in energy transfer towards acceptor dyes was observed in the presence of various metal ions, attributed to excimeric emission quenching facilitated by electron transfer between the pyrene chromophore and metal ions. Interestingly, detailed studies revealed that only ATP-based co-assemblies exhibited quenching phenomena in the presence of metal ions, contrasting with heparin and ctDNA co-assemblies. Additionally, label-free detection of multi-metal ions in aqueous environments, such as Fe2+, Fe3+, and Cu2+ ions, was successfully achieved with lower detection limits of 0.01 μM (3 ppb), 0.12 μM (30 ppb), and 0.58 μM (150 ppb) respectively. These co-assemblies hold significant promise for practical applications in environmental and biomedical sensing, enabling sensitive monitoring of metal ion concentrations.

Recent Advances in Functional Nanomaterials for Diagnostic and Sensing Using Self-Assembled Monolayers

Functional nanomaterials have attracted attention by producing different structures in any field. These materials have several potential applications, including medicine, electronics, and energy, which provide many unique properties. These nanostructures can be synthesized using various methods, including self-assembly, which can be used for the same applications. This unique nanomaterial is increasingly being used for biological detection due to its unique optical, electrical, and mechanical properties, which provide sensitive and specific sensors for detecting biomolecules such as DNA, RNA, and proteins. This review highlights recent advances in the field and discusses the fabrication and characterization of the corresponding materials, which can be further applied in optical, magnetic, electronic, and sensor fields.

PSS functionalized and stabilized carbon nanodots for specific sensing of iron in biological medium

Carbon Quantum Dots (CQDs) are already emerged as an excellent sensing element for its exceptional behavior in fluorescence, biocompatibility, and water dispersibility. However, its poor stability, selectivity and reproducibility in complex medium still be a big problem for its practical application. To overcome this, in the work, we have developed a new type of carbon quantum dot-PSS fluorescent nanocomposites which has been used for specific Fe³⁺ detection. The polystyrene sulfonate (PSS) polymer not only stabilize the QDs but also produces specific sites for Fe³⁺ to make a co-ordinate complex via Fe³⁺-SO3. The detection limit is calculated as low as 1 ppm which is adequate for measuring Fe³⁺ in blood or water samples. The mechanism of the quenching is very specific towards the Fe³⁺ ion due to the presence of PSS which makes the sensor selective among other metal ions and possible interferences. The rapid process of sensing, simple instrumentation, and excellent performances in presence of 1 % BSA and serum samples indicates the possible application for diagnostic usage in near future.

Polymerization-induced emission (PIE) of multifunctional polyamides synthesized by Ugi polymerization and targeted imaging of lysosomes

In this paper, a series of polyamide derivatives (PAMs) containing morpholine groups were prepared by Ugi polymerization from dialdehyde, diacid, N-(2-aminoethyl)-morpholine and isonitrile compounds as novel multi-responsive fluorescent sensors. As non-conjugated light-emitting polymers, PAMs were endowed with unique polymerization-induced emission (PIE) performance at 450 nm by through-space conjugation (TSC) between heteroatoms and heterocycles. It was also found that PAMs exhibited reversible responses to the external temperature and pH values and became responsive fluorescent switches. In addition, PAMs can specifically recognize Fe³⁺ with a limit of detection (LOD) of 54 nM and the introduction of EDTA reversibly restores the fluorescence of the quenched PAMs-Fe³⁺ system. By virtue of thermosensitivity, PAMs are easily separated from the above system by changing the temperature above or below the lower critical solution temperature (LCST). It is worth noting that PIE-active PAMs with good biocompatibility can selectively accumulate in lysosomes due to the presence of morpholine groups, and its Pearson colocalization coefficient is as higher as 0.91. Furthermore, a PIE-active PAM was successfully used to track exogenous Fe³⁺ in lysosomes. In conclusion, these multi-functional PIE-active PAMs have higher potential applications in biomedical or environmental fields.

Mitochondrial-Targeted AIE-Active Fluorescent Probe Based on Tetraphenylethylene Fluorophore with Dual Positive Charge Recognition Sites for Monitoring ATP in Cells

Adenosine triphosphate (ATP), as an important intracellular energy currency produced in mitochondria, is closely related to various diseases in living organisms. Currently, the biological application of AIE fluorophore as a fluorescent probe for ATP detection in mitochondria is rarely reported. Herein, D-π-A and D-A structure-based tetraphenylethylene (TPE) fluorophores were employed to synthesize six different ATP probes (P1-P6), and the phenylboronic acid groups and dual positive charge sites of probes could interact with the vicinal diol of ribose and negatively charged triphosphate structure of ATP, respectively. However, P1 and P4 with a boronic acid group and a positive charge site had poor selectivity for ATP detection. In contrast, P2, P3, P5, and P6 with dual positive charge sites exhibited better selectivity than P1 and P4. In particular, P2 had more advantages of high sensitivity, selectivity, and good time stability for ATP detection than P3, P5, and P6, which was ascribed to its D-π-A structure, linker 1 (1,4-bis(bromomethyl)benzene), and dual positive charge recognition sites. Then, P2 was employed to detect ATP, and it exhibited a low detection limit of 3.62 μM. Moreover, P2 showed utility in the monitoring of mitochondrial ATP level fluctuations.

Enhancing Dual-State Emission in Maleimide Fluorophores through Fluorocarbon Functionalisation

Herein, a library of trifluoroethyl substituted aminomaleimide derivatives are reported with small size and enhanced emissions in both solution and solid-state. A diCH2 CF3 substituted aminochloromaleimide exhibits the most efficient dual-state emission (Φf >50 % in solution and solid-state), with reduced quenching from protic solvents. This is attributed to the reduction of electron density on the maleimide ring and suppressed π-π stacking in the solid-state. This mechanism was explored in-depth by crystallographic analysis, and modelling of the electronic distribution of HOMO-LUMO isosurfaces and NCI plots. Hence, these dual-state dyes overcome the limitations of single-state luminescence and will serve as an important step forward for this rapidly developing nascent field.

A universal strategy for the fabrication of single-photon and multiphoton NIR nanoparticles by loading organic dyes into water-soluble polymer nanosponges

The development of optical organic nanoparticles (NPs) is desirable and widely studied. However, most organic dyes are water-insoluble such that the derivatization and modification of these dyes are difficult. Herein, we demonstrated a simple platform for the fabrication of organic NPs designed with emissive properties by loading ten different organic dyes (molar masses of 479.1-1081.7 g/mol) into water-soluble polymer nanosponges composed of poly(styrene-alt-maleic acid) (PSMA). The result showed a substantial improvement over the loading of commercial dyes (3.7-50% loading) while preventing their spontaneous aggregation in aqueous solutions. This packaging strategy includes our newly synthesized organic dyes (> 85% loading) designed for OPVs (242), DSSCs (YI-1, YI-3, YI-8), and OLEDs (ADF-1-3, and DTDPTID) applications. These low-cytotoxicity organic NPs exhibited tunable fluorescence from visible to near-infrared (NIR) emission for cellular imaging and biological tracking in vivo. Moreover, PSMA NPs loaded with designed NIR-dyes were fabricated, and photodynamic therapy with these dye-loaded PSMA NPs for the photolysis of cancer cells was achieved when coupled with 808 nm laser excitation. Indeed, our work demonstrates a facile approach for increasing the biocompatibility and stability of organic dyes by loading them into water-soluble polymer-based carriers, providing a new perspective of organic optoelectronic materials in biomedical theranostic applications.

Rational design of multi-functional thermally activated delayed fluorescence emitters for both sensor and OLED applications

Non-conjugated linking as a molecular design strategy to construct multifunctional structures to achieve the TADF feature and sensor properties in a single system.

Intramolecular Charge Transfer-Based Conjugated Oligomer with Fluorescence, Efficient Photodynamics, and Photothermal Activities

To develop efficient photoactive agents with satisfactory fluorescence, photodynamic, and photothermal effects is crucial for a phototherapeutic strategy to combat cancer diseases and pathogenic microbes. Herein, a water-soluble donor-acceptor-donor (D-A-D) structured conjugated oligomer was designed and synthesized, consisting of two cyclopenta-dithiophene (CDT) units as the electron donor and boron dipyrromethene (BODIPY) as the electron acceptor. Upon excitation, dual emission was observed for CDT-BODIPY with blue and red fluorescence peaks at 463 nm and at 730 nm, respectively, which was ascribed to intramolecular charge transfer (ICT). Due to the ICT effect, the singlet-to-triplet intersystem crossing rate of CDT-BODIPY was also enhanced, leading to an outstanding photodynamic behavior to produce reactive oxygen species (ROS). Meanwhile, its low bandgap also enabled it a moderate photothermal capability with a conversion efficiency of 33.1%. Taking advantage of its phototriggered activities, this conjugated oligomer exhibited an effective inhibition behavior on the pathogenic growth of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans), which can be guided by dual-wavelength fluorescence imaging. This D-A-D type conjugated oligomer with balanced photophysical characteristics provides a promising strategy to imaging-guided photoactive therapy.

Microenvironment-tailored nanoassemblies for the diagnosis and therapy of neurodegenerative diseases

Neurodegenerative disorder is an illness involving neural dysfunction/death attributed to complex pathological processes, which eventually lead to the mortality of the host. It is generally recognized through features such as mitochondrial dysfunction, protein aggregation, oxidative stress, metal ions dyshomeostasis, membrane potential change, neuroinflammation and neurotransmitter impairment. The aforementioned neuronal dysregulations result in the formation of a complex neurodegenerative microenvironment (NME), and may interact with each other, hindering the performance of therapeutics for neurodegenerative disease (ND). Recently, smart nanoassemblies prepared from functional nanoparticles, which possess the ability to interfere with different NME factors, have shown great promise to enhance the diagnostic and therapeutic efficacy of NDs. Herein, this review highlights the recent advances of stimuli-responsive nanoassemblies that can effectively combat the NME for the management of ND. The first section outlined the NME properties and their interrelations that are exploitable for nanoscale targeting. The discussion is then extended to the controlled assembly of functional nanoparticles for the construction of stimuli-responsive nanoassemblies. Further, the applications of stimuli-responsive nanoassemblies for the enhanced diagnosis and therapy of ND are introduced. Finally, perspectives on the future development of NME-tailored nanomedicines are given.

A Schiff base sensor for relay monitoring of In3+ and Fe3+ through “off–on–off” fluorescent signals

A Schiff base N′-(3-ethoxy-2-hydroxybenzylidene)-4,5-dihydronaphtho[1,2-b]thiophene-2-carbohydrazide (LB2) was designed and synthesized and could be used as a sensor to identify In³⁺ and Fe³⁺ through fluorescence ‘off–on–off’ behavior.

Naphthalimide based fluorescent organic nanoparticles in selective sensing of Fe3+ and as a diagnostic probe for Fe2+/Fe3+ transition

Fluorescent organic nanoparticles (FONPs) have attracted considerable attention as a practical and effective platform for sensing and imaging applications. The present article delineates the fabrication of FONPs derived from the naphthalimide based histidine appended amphiphile, NID. The self-assembly of NID in 99 vol% water in DMSO led to the formation of FONPs through J-type aggregation. Aggregation-induced emission (AIE) was observed due to the pre-associated excimer of NID with bluish green emission at 470 nm along with intramolecular charge transfer (ICT). The emission of NID FONPs was utilized for selective sensing of Fe³⁺ and bioimaging of Fe³⁺ inside mammalian cells. The fluorescence intensity of the FONPs was quenched with the gradual addition of Fe³⁺ due to the formation of a 1 : 1 stoichiometric complex with the histidine residue of NID. The morphology of the FONPs transformed from spherical to spindle upon the complex formation of NID with Fe³⁺. The limit of detection (LOD) of this AIE based turn-off chemosensor for Fe³⁺ was found to be 12.5 ± 1.2 μM having high selectivity over other metal ions. On the basis of the very low cytotoxicity and selective sensing of Fe³⁺, NID FONPs were successfully employed for bioimaging of Fe³⁺ ions through fluorescence quenching within mammalian cells (NIH3T3, B16F10). Considering the varying oxidative stress inside different cells, NID FONPs were used for detecting Fe²⁺ to Fe³⁺ redox state transition selectively inside cancer cells (B16F10) in comparison to non-cancerous cells (NIH3T3). Selective sensing of cancer cells was substantiated by co-culture experiment and flow cytometry. Hence, NID FONPs can be a selective diagnostic probe for cancer cells owing to their higher H₂O₂ content.

Aqueous Systems with Tunable Fluorescence Including White-Light Emission for Anti-Counterfeiting Fluorescent Inks and Hydrogels

White-light-emitting materials have attracted wide interest for potential applications in information displays and lighting. To date, the majority of reported white-light-emitting materials have been multicomponent systems that are typically processed with organic solvents. These features are associated with complex processing, poor white-light quality, and environmental pollution. Herein, a white-light-emitting aqueous system is realized by encapsulating a fluorophore, which has a vibration-induced emission effect, in Pluronic F127 micelles. Tunable multicolor fluorescence is achieved by changing the temperature, and the use of organic solvents is effectively avoided. Through this process, white-light emission with Commission Internationale de l'Eclairage coordinates of (0.3351, 0.3326) is obtained, which is very close to pure white light, and its color rendering index is as high as 89. The fluorescence color tunability of this system could be performed in a wide temperature range, rendering it a potential material in optical thermometry. Besides, the aqueous system also allows for the application of the material as a fluorescent ink and white-light-emitting hydrogels. Information could be embedded in paper-based materials and hydrogels through the fluorescence quenching effect of iron ions (Fe³⁺) on the fluorophore. Fluorescence could then be recovered upon removal of Fe³⁺ by adenosine 5'-triphosphate. Thus, fluorescent patterning and triple-mode anti-counterfeiting could be expected due to the temperature-sensitive emission, fluorescence quenching, and recovering properties.

Revisiting imidazolium receptors for the recognition of anions: highlighted research during 2010-2019

Imidazolium based receptors selectively recognize anions, and have received more and more attention. In 2006 and 2010, we reviewed the mechanism and progress of imidazolium salt recognition of anions, respectively. In the past ten years, new developments have emerged in this area, including some new imidazolium motifs and the identification of a wider variety of biological anions. In this review, we discuss the progress of imidazolium receptors for the recognition of anions in the period of 2010-2019 and highlight the trends in this area. We first classify receptors based on motifs, including some newly emerging receptors, as well as new advances in existing receptor types at this stage. Then we discuss separately according to the types of anions, including ATP, GTP, DNA and RNA.

Trisaminocyclopropenium Cations as Small-Molecule Organic Fluorophores: Design Guidelines and Bioimaging Applications

The discovery of fluorescence two centuries ago ushered in, what is today, an illuminating field of science rooted in the rational design of photochromic molecules for task-specific bio-, material-, and medical-driven applications. Today, this includes applications in bioimaging and diagnosis, photodynamic therapy regimes, in addition to photovoltaic devices and solar cells, among a vast multitude of other usages. In furthering this indispensable area of daily life and modern-day scientific research, we report herein the synthesis of a class of trisaminocyclopropenium fluorophores along with a systematic investigation of their unique molecular and electronic dependent photophysical properties. Among these fluorophores, tris[N(naphthalen-2-ylmethyl)phenylamino] cyclopropenium chloride (TNTPC) displayed a strong photophysical profile including a 0.92 quantum yield ascribed to intramolecular charge transfer and intramolecular through-space conjugation. Moreover, this cyclopropenium-based fluorophore functions as a competent imaging agent for DNA visualization and nuclear counterstaining in cell culture. To facilitate the broader use of these compounds, design principles supported by density functional theory calculations for engineering analogs of this class of fluorophores are offered. Collectively, this study adds to the burgeoning interest in cyclopropenium compounds and their unique properties as fluorophores with uses in bioimaging applications.

Fluorescent Copolymers for Bacterial Bioimaging and Viability Detection

Novel fluorescent labels with high photostability and high biocompatibility are required for microbiological imaging and detection. Here, we present a green fluorescent polymer chain (GFPC), designed to be nontoxic and water-soluble, for multicolor bioimaging and real-time bacterial viability determination. The copolymer is synthesized using a straightforward one-pot reversible addition-fragmentation chain-transfer (RAFT) polymerization technique. We show that GFPC does not influence bacterial growth and is stable for several hours in a complex growth medium and in the presence of bacteria. GFPC allows the labeling of the bacterial cytoplasm for multicolor bacterial bioimaging applications. It can be used in combination with propidium iodide (PI) to develop a rapid and reliable protocol to distinguish and quantify, in real time, by flow cytometry, live and dead bacteria.

DNAzyme-Powered Three-Dimensional DNA Walker Nanoprobe for Detection Amyloid β-Peptide Oligomer in Living Cells and in Vivo

Amyloid β-peptide oligomer (AβO) is widely acknowledged as the promising biomarker for the diagnosis of Alzheimer's disease (AD). In this work, we designed a three-dimensional (3D) DNA walker nanoprobe for AβO detection and real-time imaging in living cells and in vivo. The presence of AβO triggered the DNAzyme walking strand to cleave the fluorophore (TAMRA)-labeled substrate strand modified on the gold nanoparticle (AuNP) surface and release TAMRA-labeled DNA fragment, resulting in the recovery of fluorescent signal. The entire process was autonomous and continuous, without external fuel strands or protease, and finally produced plenty of TAMRA fluorescence, achieving signal amplification effect. The nanoprobe enabled the quantitative detection of AβO in vitro, and the limit of detection was 22.3 pM. Given the good biocompatibility of 3D DNA walker nanoprobe, we extended this enzyme-free signal amplification method to real-time imaging of AβO. Under the microscope, nanoprobe accurately located and visualized the distribution of AβO in living cells. Moreover, in vivo imaging results showed that our nanoprobe could be used to effectively distinguish the AD mice from the wild-type mice. This nanoprobe with the advantages of great sensitivity, high specificity, and convenience, provides an outstanding prospect for AD's early diagnosis development.

Isocyanoacetate-Aldehyde Polymerization: A Facile Tool toward Functional Oxazoline-Containing Polymers

As an important nitrogen source, isocyanides have been involved in numerous organic reactions. As a result, many complicated compounds have been successfully synthesized through isocyanide chemistry. However, compared with its popular research in organic reactions, the application of isocyanides in polymerization is less investigated. In this work, a new polymerization based on isocyanide monomers is established. By simply mixing diisocyanoacetates and dialdehydes in the presence of a catalytic system of CuCl/PPh₃ /organobase in dichloromethane at room temperature readily produces soluble and thermally stable oxazoline-containing polymers with moderate weight-averaged molecular weights (M_w up to 11 200) in excellent yields (up to 97%) after 6 h. Furthermore, introducing the tetraphenylethene moiety into the main chains endows the resultant polymers with aggregation-induced emission, which can function as fluorescent probes for Fe³⁺ ion detection with high sensitivity and selectivity. This work not only enriches the family of isocyanide-based polymerizations but also provides an efficient tool for the preparation of functional heterocycle-containing polymers.

Light-Emitting Multifunctional Maleic Acid-co-2-(N-(hydroxymethyl)acrylamido)succinic Acid-co-N-(hydroxymethyl)acrylamide for Fe(III) Sensing, Removal, and Cell Imaging

The intrinsically fluorescent highly hydrophilic multifunctional aliphatic terpolymer, maleic acid (MA)-co-2-(N-(hydroxymethyl)acrylamido)succinic acid (NHASA)-co-N-(hydroxymethyl)acrylamide (NHMA), that is, 1, was designed and synthesized via C-C/N-C-coupled in situ allocation of a fluorophore monomer, that is, NHASA, composed of amido and carboxylic acid functionalities in the polymerization of two nonemissive MA and NHMA. The scalable and reusable intrinsically fluorescent biocompatible 1 was suitable for sensing and high-performance adsorptive exclusion of Fe(III), along with the imaging of Madin-Darby canine kidney cells. The structure of 1, in situ fluorophore monomer, aggregation-induced enhanced emission, cell-imaging ability, and superadsorption mechanism were studied via microstructural analyses using 1H/13C NMR, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic absorption spectroscopy, ultraviolet-visible spectroscopy, thermogravimetric analysis, dynamic light scattering, high-resolution transmission electron microscopy, solid-state fluorescence, fluorescence lifetime, and fluorescence imaging, along with measuring kinetics, isotherms, and thermodynamic parameters. The location, electronic structures, and geometries of the fluorophore and absorption and emission properties of 1 were investigated using density functional theory and natural transition orbital analyses. The limit of detection and the maximum adsorption capacity were 2.45 × 10-7 M and 542.81 mg g-1, respectively.

Self-assembly of imidazolium/benzimidazolium cationic receptors: their environmental and biological applications

This review highlights the applications of imidazolium based cationic receptors for sensing of biomolecules and catalysis.

Recent Advances in AIEgens for Metal Ion Biosensing and Bioimaging

Metal ions play important roles in biological system. Approaches capable of selective and sensitive detection of metal ions in living biosystems provide in situ information and have attracted remarkable research attentions. Among these, fluorescence probes with aggregation-induced emission (AIE) behavior offer unique properties. A variety of AIE fluorogens (AIEgens) have been developed in the past decades for tracing metal ions. This review highlights recent advances (since 2015) in AIE-based sensors for detecting metal ions in biological systems. Major concerns will be devoted to the design principles, sensing performance, and bioimaging applications.

Rational Design of Dual-State Emission Luminogens with Solvatochromism by Combining a Partially Shared Donor-Acceptor Pattern and Twisted Structures

We report a general design strategy for a new class of luminogens with dual-state emission (DSEgens) that are brightly emissive in both the solution and solid state, with solvatochromism properties, by constructing a partially shared donor-acceptor pattern based on a twisted molecule. The DSEgens with bright fluorescence emission in both the solid and solution state demonstrate a unique solvatochromism behaviour depending on solvent polarity and thus may have applications in anti-counterfeiting.

Plasma Treatment Conversion of Phenolic Compounds into Fluorescent Organic Nanoparticles for Cell Imaging

Fluorescent organic nanoparticles (FONs) are promising alternatives for biological imaging applications owing to the increasing concerns over the potential toxicity and poor degradability of inorganic particles-based probes. However, synthesis of stable, small-sized FONs in aqueous media remains challenging. Inspired by the self-polymerization chemistry of phenolic compounds, we demonstrate ultrafast synthesis of FONs (phenolic compound-derived FONs, PhFONs) from a variety of molecular building blocks including dopamine, norepinephrine, pyrogallol, and gallic acid, simply by nontherml plasma treatment at the aqueous interface. Specifically, using dopamine as the precursor, poly(dopamine) (PD)-FONs featuring a small size of 3 nm are obtained within 1 min. Compositional and structural characterizations confirm the polymeric architectures in PD-FONs. The PhFONs, with multicolor emissions, excellent biocompatibility, high stability, and size-dependent access into cell nucleus, are suitable for live cell imaging and developing nucleus-targeting imaging platforms.

A Highly Selective "Turn-on" Fluorescent Probe for Detection of Fe3+ in Cells

A new "turn-on" fluorescent probe Py based on rhodamine and piperonaldehyde was designed and synthesized for detecting Fe³⁺ in cells. The free probe Py was non-fluorescent. While only upon addition of Fe³⁺, the significant increase of the fluorescence and color were observed which could be visible directly by "naked-eye". The probe Py shows high selectivity and sensitivity for Fe³⁺ over other common metal ions in EtOH-H₂O (3/2, v/v) mixed solution. The association constant and the detection limit were calculated to be 4.81 × 10⁴ M^-1 and 1.18 × 10^-8 mol/L respectively. The introduction of piperonaldehyde unit could increase probe rigidity which could enhance its optical properties. Meanwhile, the binding mode between Py and Fe³⁺ was found to be a 1:1 complex formation. The density functional theory (DFT) calculations were performed which would further confirm the recognition mechanism between probe Py and Fe³⁺. In addition, the probe has been proved to be reversible for detecting Fe³⁺. Moreover, the probe Py was used to detect Fe³⁺ in cells successfully.

A Dual Associated-Functional Fluorescent Switch: From Alternate Detection Cycle for Fe(III) and pH to Molecular Logic Operations

With the expansion and deepening of scientific research, dual-functional or multifunctional materials are urgently needed to replace those for single application. Herein, a fluorescence sensing system based on an In(III)-organic complex with in situ Lewis acid sites has been constructed, exhibiting high sensitivity for the detection of Fe(III) ions with a low detection limit of 3.95 μM and a short response time of within 10 s. It is noteworthy that the quenched fluorescence of the Fe(III)-incorporated sample could be reopened linearly with an increase of alkalinity, followed by the reactivation of its functionality to identify Fe(III) ions, forming an alternate detection cycle for Fe(III) and pH with off-on-off fluorescent switch characteristics. Considering its unique molecular recognition capability, an advanced three-input (Fe(III), EDTA, and OH^-) and two-output (B440 and G489) Boolean logic operation comprising BUFF, NOT, OR, and AND logic gates was integrated, possessing potential applications in intelligent multianalyte sensing systems.