Boron-Salphen Conjugate based Molecular Probe Exhibiting Fluorescence On-Off-On Response in Detection of Cu2+ and ATP through Displacement Approach

Synthesis and photophysical properties of a fluorescent probe HBD is described. Probe upon interaction with metal ions, anions and nucleoside pyrophosphates (NPPs) showed fluorescence quenching with Cu2+ due to chelation enhanced quenching effect (CHEQ). Moreover, interaction of ensemble HBD.Cu2+ with anions and NPPs showed fluorescence "turn-On" response with ATP selectively. "On-Off-On" responses observed with Cu2+ and ATP is attributed to an interplay between ESIPT and TICT processes. Cyclic voltammogram of probe exhibited quasi-reversible redox behaviour with three oxidation and two reduction potentials and the change in band gaps of probe suggested the interaction with Cu2+ and ATP. The 2 : 1 and 1 : 1 binding stoichiometry for an interaction between probe and Cu2+ (LOD, 62 nM) and ensemble, HBD.Cu2+ with ATP (LOD, 0.4 μM) respectively are realised by Job's plot and HRMS data. Cell imaging studies carried out to detect Cu2+ and ATP in HeLa cells. Also, the output emission observed with Cu2+ and ATP is utilized to construct an implication (IMP) logic gate. Test paper strips showed naked-eye visible color responses to detect Cu2+ and ATP. In real water samples probe successfully detected copper (0.03 μM) between 5-6.5 ppb level (ICP-MS method).

Chemically fueled dynamic switching between assembly-encoded emissions

Self-assembly provides access to non-covalently synthesized supramolecular materials with distinct properties from a single building block. However, dynamic switching between functional states still remains challenging, but holds enormous potential in material chemistry to design smart materials. Herein, we demonstrate a chemical fuel-mediated strategy to dynamically switch between two distinctly emissive aggregates, originating from the self-assembly of a naphthalimide-appended peptide building block. A molecularly dissolved building block shows very weak blue emission, whereas, in the assembled state (Agg-1), it shows cyan emission through π stacking-mediated excimer emission. The addition of a chemical fuel, ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC), converts the terminal aspartic acid present in the building block to an intra-molecularly cyclized anhydride in situ forming a second aggregated state, Agg-2, by changing the molecular packing, thereby transforming the emission to strong blue. Interestingly, the anhydride gets hydrolyzed gradually to reform Agg-1 and the initial cyan emission is restored. The kinetic stability of the strong blue emissive aggregate, Agg-2, can be regulated by the added concentration of the chemical fuel. Moreover, we expand the scope of this system within an agarose gel matrix, which allows us to gain spatiotemporal control over the properties, thereby producing a self-erasable writing system where the chemical fuel acts as the ink.

Approaching Tryptophan-Derived Polynorbornene Fluorescent Chemosensors: Synthesis, Characterization, and Sensing Ability for Biomedical Applications as Biomarkers for Detecting Fe2+ Ions

We present a novel group of tryptophan (Trp)-based fluorescent polymeric probes synthesized via ring-opening metathesis polymerization (ROMP) of Trp-derived norbornene monomers. These probes, in mono- and disubstituted forms, incorporate amide and ester anchoring groups. The quantity of Trp substituents did not affect fluorescence selectivity but influenced quenching percentage. Poly-diamide-Trp, Poly-monoamide-Trp, Poly-diester-Trp, and Poly-monoester-Trp probes displayed selective detection of Fe2+ and Fe3+ ions with fluorescence on-off characteristics. Poly-diamide-Trp and Poly-monoamide-Trp exhibited a limit of detection (LOD) for Fe2+ and Fe3+ ions of 0.86-11.32 μM, while Poly-diester-Trp and Poly-monoester-Trp showed higher LODs (21.8-108.7 μM). These probes exhibited high selectivity over Fe2+, a crucial metal ion in the body known for its redox properties causing oxidative stress and cell damage. Cell cytotoxicity tests in various cell types confirmed biocompatibility. Additionally, Poly-diamide-Trp displayed excellent cell permeability and iron ion detection in EA.hy926 cells, suggesting potential for bioimaging and clinical applications.

A novel fluorescent "Off-On" probe based on phenanthro[9,10-d]imidazole conjugated polymers (PIPF) for Cr3+ detection with high selectivity and sensitivity

Trivalent chromium (Cr3+) causes serious environmental pollution, degradation of the quality of edible agricultural products and human diseases. A novel phenanthro[9,10-d]imidazole-derived conjugated polymers (PIPF) was obtained from 4-(5,10-dibromo-1H-phenanthro[9,10-d]imidazol-2-yl)phenol and diethyl 4,4'-(2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-fluorene-9,9-diyl)dibutyrate by Suzuki polymerization reaction, which was reasonably demonstrated by 1H NMR spectroscopy, infrared spectroscopy and quantum chemical calculations. The PIPF exhibits a "turn-on" fluorescence response to Cr3+ in DMSO/H2O (98:2, v/v) with naked-eye detection. The limit of detection for Cr3+ was calculated to be 0.073 μM with a linear range of 3-9 μM. The possible mechanism of the PIPF-based Cr3+ fluorescence "turn-on" sensor is due to the inhibition of the PET process by the coordination of Cr3+ to the hexaalkyl ester carbon chain of PIPF (RCOO-). The high sensitivity, good selectivity, and utility of this sensor indicated that PIPF-based "turn-on" fluorescence sensor is a potential fluorescence application for measuring Cr3+ in environmental samples.

An environmentally sensitive zinc-selective two-photon NIR fluorescent turn-on probe and zinc sensing in stroke

A two-photon near infrared (NIR) fluorescence turn-on sensor with high selectivity and sensitivity for Zn2+ detection has been developed. This sensor exhibits a large Stokes' shift (∼300 nm) and can be excited from 900 to 1000 nm, with an emission wavelength of ∼785 nm, making it ideal for imaging in biological tissues. The sensor's high selectivity for Zn2+ over other structurally similar cations, such as Cd2+, makes it a promising tool for monitoring zinc ion levels in biological systems. Given the high concentration of zinc in thrombi, this sensor could provide a useful tool for in vivo thrombus imaging.

Soybean-Based Bio-Adhesives: Role of Diamine on the Adhesive Properties

One possible approach to achieving sustainable development in the materials sector is to produce polymers from plant oils (POs), which are renewable and environmentally beneficial. Polymers with a high concentration of functional groups can be used as cross-linking agents to enhance the properties of epoxidized POs (epoxidation of plant oil)-based polymers. In this work, a unique resin with novel properties and potential uses was produced by cross-linking epoxidized soybean oil (ESO) with branched and flexible polyamines by ring-opening and amidation polymerizations. This approach is straightforward and ecologically benign. After curing, melamine pentane diamine (MPD) polymer maintained its position as the strongest structural adhesive among the synthesized resins, with a bonding strength of almost 2000 kPa for stainless steel; irrespective of the temperature, stainless steel consistently outperforms melamine ethylene diamine-ESO resin in strength comparisons. At 100 °C, stainless steel has a lap shear strength of about 300 kPa, which is far higher than copper and aluminum; at 180 °C, this value increases by another 750 kPa. While MPD-ESO resin has a shear strength of 1996 kPa at 180 °C, melamine butane diamine-ESO resin has a shear strength of only 1220 kPa.

Polydiacetylene rhodaminebased colorimetric chemosensor for Au3+ detection

A novel platform of a polydiacetylene combined with rhodamine B (PDA-Rho) colorimetric chemosensor array was prepared from a diacetylene monomer and rhodamine B derivative. Rhodamine B derivative as the ion-recognition element was embedded in the polydiacetylene matrix. To fabricate chemosensor, diacetylene monomer connected rhodamine B derivatives (DA-Rho) was coated onto a filter paper surface via drop-casting technique and transformed to polydiacetylene by polymerisation through ultraviolet (UV) irradiation. From the result, PDA-Rhoen exhibited high sensitivity and selectivity for Au3+ and could be monitored directly by naked eyes providing a fast, portable and easy-to-use as a molecular device in the real system. The DFT calculation results showed a stable complex between PDA-Rho and Au3+. We believe that, this method offers a sensitive and accurate process for Au3+ ion detection in real environmental and biological applications.

Interfacially Confined Dynamic Reaction Resulted to Fluorescent Nanofilms Depicting High-Performance Ammonia Sensing

Sensing materials innovation plays a crucial role in the development of high-performance film-based fluorescent sensors (FFSs). In our current study, we present the innovative fabrication of four fluorescent nanofilms via interfacially confined dynamic reaction of a specially designed fluorescent building block, a new boron-coordinated compound (NI-CHO), with a chosen one, benzene-1,3,5-tricarbohydrazide (BTH). The nanofilms as prepared are robust, uniform, flexible, and thickness tunable, at least from 40 to 1500 nm. The fabricated FFSs based on Film 3, one of the four nanofilms, shows highly selective and fully reversible response to NH3 vapor with an experimental detection limit of <0.1 ppm and a response time of 0.2 s. The unprecedented high performance of the nanofilm is ascribed to the specific quenching of its fluorescence emission owing to formation of an excited-state complex between the sensing unit and the analyte molecule. Efficient mass transfer also contributes to the high performance owing to the porous adlayer structure of the nanofilm. This work provides an example to show how to develop a high-performance sensing film via controlling the film's structure, especially the thickness.

A flavonol-labelled cellulose fluorescent probe combined with composite fluorescent film imaging and smartphone technology for the detection of Fe3

Fe3+ is one of the most widely distributed and abundant elements on earth. Realizing efficient and real-time monitoring of Fe3+ is of great significance for the natural environment and the health of living organisms. In this paper, a flavonol-labelled cellulose-based fluorescent probe (ACHM) was synthesized by using dialdehyde cellulose (DAC) as the backbone and combining with flavonol derivatives (AHM - 1). The mechanism of recognizing Fe3+ was verified by characterizing the structure of ACHM by NMR, HRMS (High Resolution Mass Spectrometry), FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), TG (Thermogravimetry) and SEM (Scanning Electron Microscopy). The H2O solution of the probe ACHM showed good fluorescence properties. It has quenching fluorescence properties for Fe3+, with a low limit of detection (LOD) of 0.10 μM and a fast response time of only 20 s. In addition, in order to expand the application range of the probe, ACHM was prepared as a fluorescent composite film with an average tensile strength of 32.9 MPa and an average elongation at break of 3.39 %. It shows its superiority in mechanical properties. The probe also demonstrated its practical application value for detecting Fe3+ in smartphone imaging applications.

A dual encapsulation strategy to generate anion-responsive luminescent lanthanide hydrogels

We report a new method to generate ion-responsive luminescent hydrogels, involving encapsulation of a luminescent lanthanide probe within crosslinked amphiphilic polymer particles and subsequent entrapment within a hydrogel. The resulting hydrogels are capable of reversible bicarbonate sensing, exhibit no leaching, and can be tuned for a range of sensing applications.

Conjugated Polyelectrolyte Containing a High Density of Pendant Phenylboronic Acid Groups for Dopamine Detection

A fluorescent sensing system based on a conjugated polyelectrolyte was constructed to detect dopamine (DA) in complex samples. The conjugated polymer PFPE-PBA with poly[fluorenyl-alt-p-phenyleneethynylene] (PFPE) as the backbone and carrying four pendant phenylboronic acid (PBA) groups in each repeat unit was synthesized. PFPE-PBA was found to have good solubility in polar solvents. After optimization, glycine-NaOH at pH 10 was selected as the buffer, and the solvent composition of the system was set to methanol/water (9/1 by volume). Titration experiments showed that DA could effectively quench the fluorescence of the polymer solution with a response time within 60 s and a limit of detection of 23 nM. Polyols, cations, and other possible interfering substances do not significantly affect the fluorescence of the polymer, thereby allowing for the highly selective detection of DA. Furthermore, quantitative determination of DA in spiked serum and artificial urine samples was successfully demonstrated, with recoveries ranging from 96.7 to 104%. Preliminary mechanism studies suggest that the pedant PBAs capture DA via reaction with the catechol group, and the fluorescence quenching is most likely due to the photoinduced electron transfer between the aromatic part of DA and the conjugated backbone. This study provides a general strategy for the future design of conjugated polyelectrolyte-based sensing systems.

An Ir(III) cyclometalate-functionalized molecularly imprinted polymer: photophysics, photochemistry and chemosensory applications

A luminescent trimethylamine (TMA) sensor, PTMA-Ir, has been designed and synthesized through immobilizing a phosphorescent iridium(III) complex on a TMA-imprinted polymer. Detailed study shows that the quenching of phosphorescence of PTMA-Ir can serve as a reporter for the binding of TMA on the imprinting sites, thus providing a sensitive, selective, and rapid detection of TMA in both aqueous solutions and gaseous states. Loading PTMA-Ir on filter paper produced a deposition T-Ir, the phosphorescence of which is quenched within 5 s upon exposure to TMA vapor with detection limits of 9.0 ± 0.1 ppm under argon and 15.0 ± 0.1 ppm in an air atmosphere. This work provided an effective method for establishing an imprinting polymer-immobilized luminescent amine sensor.

The syntheses of fluorescein-based conjugated microporous polymers by direct arylation polymerization and fluorescence sensing Fe3+ in aqueous solutions

Determination of ferri ions in environment and human bodies is very important for environmental protection and disease diagnosis. Recently, conjugated microporous polymers (CMPs) used for fluorescence sensing metal ions have attracted much attention, but this technique is done in organic solvents. In this study, the two new fluorescein-based CMPs named FLEDOT and FLBTh were synthesized by "greener method", direct arylation polymerization, with tetraiodofluorescein sodium salt (TIFS) and 3,4-ethylenedioxy thiophene or 2,2'-bithiophene. Pleasely, the prepared fluorescein-based CMPs can fluorescently sense for Fe3+ in water with high sensitivity and selectivity. The quenching constants (KSV) of FLEDOT and FLBTh are 1.51 × 104 and 1.09 × 104 L mol-1, and the limits of detection (LODs) as low as 1.99 × 10-10 and 2.75 × 10-10 mol L-1, which are comparable to the sensitivity found in organic solvents' dispersions such as N,N-dimethylformamide (DMF)' dispersions. UV-Vis absorption spectra show that the fluorescence quenching mechanisms of Fe3+ are absorption competition quenching process and energy transfer process.

Acid-base responsive multifunctional poly(formyl sulfide)s through a facile catalyst-free click polymerization of aldehyde-activated internal diynes and dithiols

Acid-base equilibria play a critical role in biological processes and environmental systems. The development of innovative fluorescent polymeric materials to monitor acid-base equilibria is highly desirable. Herein, a novel catalyst-free click polymerization of aldehyde-activated internal diynes and dithiols was established, and exclusively Markovnikov poly(formyl sulfide)s (PFSs) with high molecular weights and moderate stereoregularity were produced in high yields. Because of the aromatic units and sulfur atoms in their main chains, these polymers possessed high refractive index values. By introducing the fluorene and aldehyde moieties, the resulting PFSs could act as a fluorescent sensor for sensitive hydrazine detection. Taking advantage of the reaction of the aldehyde group and hydrazine, imino-PFSs with remarkable and reversible fluorescence change through alternating fumigation with HCl and NH3 were easily acquired and further applied in multicolor patterning, a rewritable material and quadruple-mode information encryption. Additionally, a test strip of protonated imino-polymer for the tracking of bioamines in situ generated from marine product spoilage was also demonstrated. Collectively, this work not only provides a powerful click polymerization to enrich the multiplicity of sulfur-containing materials, but also opens up enormous opportunities for these functional polysulfides in diverse applications.

Multifunctional bisalkynylplatinum(II) bipyridine complexes with rhodamine-like ligands featuring near-infrared phosphorescence and delayed fluorescence

A series of platinum(II) bipyridine complexes with two rhodamine-like alkynyl (Rhodyne) ligands were developed to show chemo-induced "ON-OFF" switching capabilities with exceptional near-infrared phosphorescence and delayed fluorescence. This study contributes to the design of versatile photosensitizers with multiple functionalities, including metal ion and biomolecule sensing, photodynamic therapy, and optoelectronics.

Current trends in the detection and removal of heavy metal ions using functional materials

The shortage of freshwater resources caused by heavy metal pollution is an acute global issue, which has a great impact on environmental protection and human health. Therefore, the exploitation of new strategies for designing and synthesizing green, efficient, and economical materials for the detection and removal of heavy metal ions is crucial. Among the various methods for the detection and removal of heavy ions, advanced functional systems including nanomaterials, polymers, porous materials, and biomaterials have attracted considerable attention over the past several years due to their capabilities of real-time detection, excellent removal efficiency, anti-interference, quick response, high selectivity, and low limit of detection. In this tutorial review, we review the general design principles underlying the aforementioned functional materials, and in particular highlight the fundamental mechanisms and specific examples of detecting and removing heavy metal ions. Additionally, the methods which enhance water purification quality using these functional materials have been reviewed, also current challenges and opportunities in this exciting field have been highlighted, including the fabrication, subsequent treatment, and potential future applications of such functional materials. We envision that this tutorial review will provide invaluable guidance for the design of functional materials tailored towards the detection and removal of heavy metals, thereby expediting the development of high-performance materials and fostering the development of more efficient approaches to water pollution remediation.

Zn(II)-Dipicolylamine-Attached Amphiphilic Polythiophene for Quantitative Pattern Recognition of Oxyanions in Mixtures

Herein, we propose a novel amphiphilic polythiophene-based chemosensor functionalized with a Zn(II)-dipicolylamine side chain (1poly  ⋅ Zn) for the pattern recognition of oxyanions. Optical changes in amphiphilic 1poly  ⋅ Zn can be induced by the formation of a random coil from a backbone-planarized structure upon the addition of target oxyanions, which results in blueshifts in the UV-vis absorption spectra and turn-on-type fluorescence responses. Dynamic behavior in a polythiophene wire and/or among wires could be a driving force for obtaining visible color changes, while the molecular wire effect is dominant in obtaining fluorescence sensor responses. Notably, the magnitude of optical changes in 1poly  ⋅ Zn has depended on differences in properties of oxyanions, such as their binding affinity, hydrophilicity, and molecular geometry. Thus, various colorimetric and fluorescence response patterns of 1poly  ⋅ Zn to oxyanions were obtained, albeit using a single chemosensor. A constructed information-rich dataset was applied to pattern recognition for the simultaneous group categorization of phosphate and carboxylate groups and the prediction of similar structural oxyanions at a different order of concentrations in their mixture solutions.

NIR squaraine dyes for dual colorimetric and fluorescent determination of Fe3+, Cu2+, and Hg2+ ions

Four benzoindolenine-based squaraine dyes (SQs), which have the advantages of intense visible and near-infrared (NIR) absorption and emission (λ_abs/max 663-695 nm, λ_em/max 686-730 nm) were synthesized and characterized by UV-vis absorption, fluorescent emission spectrophotometry, FTIR, NMR and HRMS analysis. Among them, BBSQ showed excellent performance, which exhibited high selectivity to Fe³⁺, Cu²⁺, and Hg²⁺ in acetonitrile solution even in the presence of other competitive metal ions, accompanied by obvious color change easily detected by the naked eye. The detection limit was 14.17 μM for Fe³⁺ and 6.06 μM for Cu²⁺. Most importantly, the response mechanism of BBSQ to Fe³⁺, Cu²⁺, and Hg²⁺ involves the coordination of BBSQ and metal ions through the O atom on the central squarate ring, N atom, and olefin π bond of BBSQ and has been demonstrated by Job's plot, FTIR, and ¹H NMR titration analyses. Furthermore, BBSQ was applied successfully to detect Fe³⁺, Cu²⁺, and Hg²⁺ in thin-layer chromatography (TLC) plates with good precision and is quite promising for the quantitative detection of Fe³⁺ and Cu²⁺ ions in water samples.

Electrochemical and fluorescent dual-mode sensor of acetylcholinesterase activity and inhibition based on MnO2@PD-coated surface

We developed an electrochemical and fluorescent dual-mode sensor for assessing acetylcholinesterase (AChE) activity and inhibition by taking advantage of the high redox sensitivity of surface-coated mesoporous MnO₂@polymer dot (MnO₂@PD) towards AChE. The following phenomena constitute the basis of the detection mechanism: fluorescence resonance energy transfer (FRET) effect between MnO₂ and PD; catalytic hydrolysis of acetylthiocholine (ATCh) to thiocholine (TCh) by AChE expressed by PC-12 cells, inducing fluorescence restoration and change in the conductivity of the system due to MnO₂ decomposition; the presence of the inhibitor neostigmine preventing the conversion of ATCh to TCh. The surface-coated biosensor presents both fluorescence-based and electrochemical approaches for effectively monitoring AChE activity and inhibition. The fluorescence approach is based on the fluorescent "on/off" property of the system caused by MnO₂ breakdown after interaction with TCh and the subsequent release of PDs. The conductivity of the coated electrode decreased dramatically as AChE concentration increased, resulting in electrochemical sensing of AChE activity and inhibition screening. Real-time wireless sensing can be conducted using a smartphone to monitor the resistance change, investigating the potential use of MnO₂@PD nanocomposites in biological studies, and offering a real-time redox-fluorescent test for AChE activity monitoring and inhibitor screening.

Hybrid films composed of ethyl(hydroxyethyl)cellulose and silica xerogel functionalized with a fluorogenic chemosensor for the detection of mercury in water

Ethyl(hydroxyethyl)cellulose (EHEC) and a silica-based xerogel (SBX) were functionalized with a (18-crown-6)-styrylpyridine precursor (1) to obtain the modified polymers EHEC-1 and SBX-1, respectively. Films were obtained and the resulting materials were used as fluorogenic devices for the detection of Hg²⁺ in water. The films produced from EHEC-1 showed high water retention, making it difficult to apply as a reusable optical chemosensor. Since SBXs are recognized in the literature for their hydrophobicity, a hybrid film composed of EHEC and SBX-1 which did not show water retention was produced and characterized. This system showed rapid response time, outstanding selectivity compared to several other studied metal ions, and sensitivity for the detection of Hg²⁺ in water. The detection limit for this material using fluorescence technique was 2 ppb (∼10^-8 mol L^-1). The reversibility of the complex formed between EHEC-SBX-1 film and Hg²⁺ was demonstrated by the addition of cysteine to the medium. The result obtained also allowed the assembly of INHIBIT and IMPLICATION molecular logic gates, using Hg²⁺ and cysteine as inputs. The results described in this article have important significance in the development of novel reversible fluorogenic chemosensors and adsorbent materials for the effective removal of Hg²⁺ ions.

One-Pot Synthesis of Robust Fluorescent Nanocomposite Gel via Frontal Polymerization

Fluorescent nanocomposite gels have attracted increasing attention due to their excellent optical properties, as well as enhanced mechanical strength originating from the nanoparticles. At present, two-step methods are usually employed, where fluorescent nanoparticles are firstly prepared, followed by mixing with gel precursor to achieve the final products after gelation, which suffer from the disadvantages of a tedious and time-consuming process. Thus, the development of a facile strategy is highly desirable, which still remains an obstacle. Herein, a new one-pot synthesis method towards robust fluorescent nanocomposite gels via frontal polymerization (FP) is proposed, where small molecular precursors (citric acid (CA) and urea, or L-cysteine) and gel precursor (vinyl monomers) are mixed together as co-reactants. During the FP process, a lot of heat release gives rise to the generation of carbonized polymer dots (CPDs). Thus, companying with the propagating of the polymerization, the production of fluorescent CPDs/gel composite is completed. In addition, as a nanofiller, CPDs dramatically enhance the mechanical property of the CPDs/gel composite. This work proposes a new fast and efficient one-pot strategy for the production of CPDs/gel composite, which will guide the development of high-performance polymer nanocomposites through an in situ synchronous reaction fashion.

Fluorescence-Amplified Origami Microneedle Device for Quantitatively Monitoring Blood Glucose

Exploration of clinically acceptable blood glucose monitors has been engaging in the past decades, yet the ability to quantitatively detect blood glucose in a painless, accurate, and highly sensitive manner remains limited. Herein, a fluorescence-amplified origami microneedle (FAOM) device is described that integrates tubular DNA-origami nanostructures and glucose oxidase molecules into its inner network to quantitatively monitor blood glucose. The skin-attached FAOM device can collect glucose molecules in situ and transfer the input into a proton signal after the oxidase's catalysis. The proton-driven mechanical reconfiguration of DNA-origami tubes separates fluorescent molecules and their quenchers, eventually amplifying the glucose-correlated fluorescence signal. The function equation established on clinical examinees suggests that FAOM can report blood glucose in a highly sensitive and quantitative manner. In clinical blind tests, the FAOM achieves well-matched accuracy (98.70 ± 4.77%) compared with a commercial blood biochemical analyzer, fully meeting the requirements of accurate blood glucose monitoring. The FAOM device can be inserted into skin tissue in a trivially painful manner and with minimal leakage of DNA origami, substantially improving the tolerance and compliance of the blood glucose test.

Molecularly Imprinted Polymer-Based Luminescent Chemosensors

Molecularly imprinted polymer (MIP)-based luminescent chemosensors combine the advantages of the highly specific molecular recognition of the imprinting sites and the high sensitivity with the luminescence detection. These advantages have drawn great attention during the past two decades. Luminescent molecularly imprinted polymers (luminescent MIPs) towards different targeted analytes are constructed with different strategies, such as the incorporation of luminescent functional monomers, physical entrapment, covalent attachment of luminescent signaling elements on the MIPs, and surface-imprinting polymerization on the luminescent nanomaterials. In this review, we will discuss the design strategies and sensing approaches of luminescent MIP-based chemosensors, as well as their selected applications in biosensing, bioimaging, food safety, and clinical diagnosis. The limitations and prospects for the future development of MIP-based luminescent chemosensors will also be discussed.

Recent advances in fluorescent and colorimetric chemosensors for the detection of chemical warfare agents: a legacy of the 21st century

Chemical warfare agents (CWAs) are among the most prominent threats to the human population, our peace, and social stability. Therefore, their detection and quantification are of utmost importance to ensure the security and protection of mankind. In recent years, significant developments have been made in supramolecular chemistry, analytical chemistry, and molecular sensors, which have improved our capability to detect CWAs. Fluorescent and colorimetric chemosensors are attractive tools that allow the selective, sensitive, cheap, portable, and real-time analysis of the potential presence of CWAs, where suitable combinations of selective recognition and transduction can be integrated. In this review, we provide a detailed discussion on recently reported molecular sensors with a specific focus on the sensing of each class of CWAs such as nerve agents, blister agents, blood agents, and other toxicants. We will also discuss the current technology used by military forces, and these discussions will include the type of instrumentation and established protocols. Finally, we will conclude this review with our outlook on the limitations and challenges in the area and summarize the potential of promising avenues for this field.

Recent Advances in Drug Release, Sensing, and Cellular Uptake of Ring-Opening Metathesis Polymerization (ROMP) Derived Poly(olefins)

The synthesis and applications of ring-opening metathesis polymerization (ROMP) derived poly(olefins) have emerged as an exciting area of great interest in the field of biomaterials science. The major focus of this mini-review is to present recent advances in the synthesis of functional materials using ROMP-derived poly(olefins) utilized for drug release, sensing, and cellular uptake in the past seven years (2015-2022). This review reveals that materials synthesized by ROMP-derived well-defined functional poly(olefins) stand to be highly promising systems for medical as well as biological studies. Thus, this review may prove to be beneficial for the design and development of new smart and flexible-functionality ROMP-based polymeric materials for various biological applications.

The spectroscopic and computational study of anthracene based chemosensor - Ag+ interactions

Here in, we demonstrate a selective detection of Ag⁺ ion by the anthracene-based schiff base sensor AMC. The recognition event among sensor AMC and Ag⁺ ion was investigated by enhanced absorption band, red-shifted quenched emission spectra, electrochemical studies and DFT computational studies. The presence of Ag⁺ ion to solution of AMC quenched almost 50 % emission intensity of the ligand band. Data from high-resolution electrospray ionization mass spectrometry (ESI-HRMS), Ag⁺ titrations, and Job's plot studies all show that Ag⁺ binds to AMC in a 1:1 stoichiometric ratio.The quantitative parameters of sensor for silver ion are determined as the limit of detection (LOD) 5.95 × 10^-7 M, and limit of quantitation (LOQ) 1.98 × 10^-8 M in the linear range 3.48-20.31 × 10^-6 M with good association affinity of 5.030 × 10³ M^-1. LMCT phenomenon from insilico studies, is in good agreement with the results obtained from other performed spectroscopic techniques. In addition, this sensor AMC was also successfully applied to real water samples for the identification and measurement of Ag⁺ ions.

A short review article on conjugated polymers

This article provides a brief review of conjugated polymers and the various typical polymerization reactions exploited by the community to synthesise different conjugated polyelectrolytes with varied conjugated backbone systems. We further discuss with detailed emphasises the mechanism involved such as photo-induced electron transfer, resonance energy transfer, and intra-molecular charge transfer in the detection or sensing of various analytes. Owing to their excellent photo-physical properties, facile synthesis, ease of functionalization, good biocompatibility, optical stability, high quantum yield, and strong fluorescence emission. Conjugated polymers have been explored for wide applications such as chemical and biological sensors, drug delivery and drug screening, cancer therapeutics and imaging. As such we believe it will be a timely review article for the community.

Promoter-regulated in vivo asymmetric self-assembly strategy to synthesize heterogeneous nanoparticles for signal amplification

Signal amplification is commonly used to enhance the sensitivity of biological analysis. Here, we present a strategy involving in vivo asymmetric self-assembly combined with promoter strength regulation to synthesize heterogeneous nanoparticles for signal amplification. Two expression vectors were constructed by genetically inserting, respectively, signal and binding molecules into the hepatitis B core antigen protein (HBcAg) structure. Because of differential expression of the two recombinant proteins in the presence of a strong promoter (T7) and a weak promoter (Tac-1) and spontaneous asymmetric self-assembly in vivo, heterogeneous HBcAg nanoparticles (NPs) with a high ratio of signal-bearing to target-binding molecules were obtained. These nanoparticles contained a large number of green fluorescent proteins as signal molecules and a small number of B1 immunoglobulin-binding domains from protein G for antibody binding, thus enabling sensitive immunoassays. As a proof of concept, improved sensitivity for antibody detection was achieved using the heterogeneous nanoparticle conjugated with a secondary antibody molecule.

Polymeric Emissive Materials Based on Dynamic Covalent Bonds

Dynamic covalent polymers, composed of dynamic covalent bonds (DCBs), have received increasing attention in the last decade due to their adaptive and reversible nature compared with common covalent linked polymers. Incorporating the DCBs into the polymeric material endows it with advanced performance including self-healing, shape memory property, and so forth. However, the emissive ability of such dynamic covalent polymeric materials has been rarely reviewed. Herein, this review has summarized DCBs-based emissive polymeric materials which are classified according to the different types of DCBs, including imine bond, acylhydrazone bond, boronic ester bond, dynamic C-C bond, as well as the reversible bonds based on Diels–Alder reaction and transesterification. The mechanism of chemical reactions and various stimuli-responsive behaviors of DCBs are introduced, followed by typical emissive polymers resulting from these DCBs. By taking advantage of the reversible nature of DCBs under chemical/physical stimuli, the constructed emissive polymeric materials show controllable and switchable emission. Finally, challenges and future trends in this field are briefly discussed in this review.

Synthesis and characterization of fluorescence poly(amidoamine) dendrimer-based pigments

In this work, we looked at how to make fluorescence hybrid poly(amidoamine) dendrimer (PAMAM) dendrimers using calcozine red 6G and coumarin end groups. After synthesis of ethylenediamine (EDA)-cored 4th generation PAMAM dendrimer (G4.0), surface functional groups is reacted with calcozine red 6G (Rh6G) and 7-methacryloyloxy-4-methylcoumarin. Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (¹H NMR), and X-ray diffraction are used to characterize the structure of synthesized fluorescent hybrid dendrimers. Optical properties are demonstrated using a fluorescence spectrophotometer, and UV–Vis–NIR reflectance spectra. According to UV–Vis–NIR reflectance spectra, hybrid dendrimers were transparent in the NIR range. Moreover, quantum yield (Φs) of hybrid dendrimers was calculated in dimethylformamide (DMF), ethanol, dimethyl sulfoxide (DMSO), and distilled water (H₂O). Dendrimers in which Rh6G was utilized to modification showed the maximum quantum yield in ethanol due to great interaction of structure with ethanol and the arrangement of ring-opened amide shape of calcozine red 6G.

Nonbenzenoid BODIPY Analogues: Synthesis, Structural Organization, Photophysical Studies, and Cell Internalization of Biocompatible N-Alkyl-Aminotroponyl Difluoroboron (Alkyl-ATB) Complexes

The alkyl-BODIPY derivatives are lipid types of fluorescent molecules that exhibit a unique structure and functions including sensing of hydrophobic microenvironments in living cells. Their synthesis involves multisteps from the core structure dipyrromethene scaffold. The alkyl-BODIPY analogues are sought to derivatize with minimal synthetic steps even by altering the core structures derived from benzenoid aromatic moiety. Recently, the nonbenzenoid scaffold (aminotropone) has been explored to synthesize troponyl-BODIPY analogues, which are fluorescent. In the repertoire of nonbenzenoid analogue, N-alkyl-aminotroponyl difluoroboron (alkyl-ATB) is rationally designed comprising long-chain hydrocarbons to explore the lipid type of fluorescent molecules. This report describes the synthesis, photophysical studies, structural organization, and biocompatibilities of ATB derivatives containing different lengths of alkyl chain at 2-aminotropone scaffold. The photophysical studies of ATB derivatives reveal their fluorescence behaviors in organic solvents (CH₃OH/CH₃CN) with a quantum yield of ∼10 to 15%. These ATB derivatives also exhibit fluorescence characters in the solid state though their quantum yield is relatively low. Cell permeability and cytotoxicity studies reveal that alkyl-ATB derivatives are permeable to HeLa/HEK293T cell lines and show negligible cytotoxicity. The biocompatibility of alkyl-ATB derivatives is studied and confirmed by cell viability (MTT) assay to the HeLa/HEK293T cell lines. Importantly, the cell internalization studies of the representative alkyl-ATB molecule by fluorescence microscopy show that octyl-ATB is efficiently detectable at the cytoplasmic membrane and cellular nucleus in HeLa cells. Hence, alkyl-ATB derivatives are potential fluorescent molecules for developing probes to visualize cellular components under a fluorescence microscope.

Cross-Linked Luminescent Polymers Based on β-Diketone-Modified Polysiloxanes and Organoeuropiumsiloxanes

Nowadays, luminescent materials attract wide attention due to their valuable characteristics and broad area of potential application. Luminescent silicone-based polymers possess unique properties, such as flexibility, hydrophobicity, thermal and chemical stabilities, etc., which allow them to be utilized in various fields, such as optoelectronics, solid-state lasers, luminescent solar concentrators, sensors, and others. In the present work, a metal-ligand interaction approach was applied to obtain new cross-linked luminescent polymers based on multiligand polysiloxanes with grafted β-diketone fragments and organoeuropiumsiloxanes containing various organic substituents. Organoeuropiumsiloxanes were utilized as a source of Eu³⁺ ions due to their compatibility with the silicon matrix. All synthesized polymers were fully characterized and their physicochemical, mechanical, self-healing, optical, and thermal properties were studied.

Synthesis and macrocyclization-induced emission enhancement of benzothiadiazole-based macrocycle

We presented an effective and universal strategy for the improvement of luminophore’s solid-state emission, i.e., macrocyclization-induced emission enhancement (MIEE), by linking luminophores through C(sp³) bridges to give a macrocycle. Benzothiadiazole-based macrocycle (BT-LC) has been synthesized by a one-step condensation of the monomer 4,7-bis(2,4-dimethoxyphenyl)−2,1,3-benzothiadiazole (BT-M) with paraformaldehyde, catalyzed by Lewis acid. In comparison with the monomer, macrocycle BT-LC produces much more intense fluorescence in the solid state (Φ_PL = 99%) and exhibits better device performance in the application of OLEDs. Single-crystal analysis and theoretical simulations reveal that the monomer can return to the ground state through a minimum energy crossing point (MECP_S1/S0), resulting in the decrease of fluorescence efficiency. For the macrocycle, its inherent structural rigidity prohibits this non-radiative relaxation process and promotes the radiative relaxation, therefore emitting intense fluorescence. More significantly, MIEE strategy has good universality that several macrocycles with different luminophores also display emission improvement.

Organic luminescent materials attract attention due to their wide application range, but many organic luminogens suffer from severe quenching effect in the aggregate state. Here, the authors demonstrate a macrocyclization induced emission enhancement by linking luminophores through methylene bridges to give a macrocycle.

Water-soluble optical sensors: keys to detect aluminium in biological environment

Metal ion plays a critical role from enzyme catalysis to cellular health and functions. The concentration of metal ions in a living system is highly regulated. Among the biologically relevant metal ions, the role and toxicity of aluminium in specific biological functions have been getting significant attention in recent years. The interaction of aluminium and the living system is unavoidable due to its high earth crust abundance, and the long-term exposure to aluminium can be fatal for life. The adverse Al3+ toxicity effects in humans result in various diseases ranging from cancers to neurogenetic disorders. Several Al3+ ions sensors have been developed over the past decades using the optical responses of synthesized molecules. However, only limited numbers of water-soluble optical sensors have been reported so far. In this review, we have confined our discussion to water-soluble Al3+ ions detection using optical methods and their utility for live-cell imaging and real-life application.

Selective, Rapid, and Ratiometric Fluorescence Sensing of Homocysteine in Live Neurons via a Reaction-Kinetics/Sequence-Differentiation Strategy Based on a Small Molecular Probe

Small molecular biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play essential roles in maintaining the redox homeostasis of biological systems, the disorders of which are closely associated with neuropathology. To date, many probes have been developed to identify Cys and GSH; however, due to the relatively low content and the high structural homology with Cys, there is still a lack of effective strategies to design probes enabling Hcy detection in physiological environments with high selectivity, high sensitivity, and rapid response. Herein, we developed a reaction-kinetics/sequence-differentiation strategy based on a dual-binding-site boron-dipyrrin (BODIPY) fluorophore, which was able to selectively distinguish Hcy from Cys and GSH within 50 s though a ratiometric fluorescence response mode. Benefiting from these features, the probe is capable of real-time imaging and quantitative analysis of intracellular Hcy in living neurons. Moreover, results of the disease-model experiments at the cellular level indicated a gradual increase of the Hcy level in neurons during the processes of aggregated amyloid-β (Aβ) peptide or ischemia treatment, which would further promote the neuron apoptosis. These findings provide the first direct experimental evidence for the impact of Alzheimer's disease and ischemic stroke on the Hcy metabolism of brain neurons and the associated neuron injury.

An Intramolecular Charge Transfer-Förster Resonance Energy Transfer Integrated Unimolecular Platform for Two-Photon Ratiometric Fluorescence Sensing of Methionine Sulfoxide Reductases in Live-Neurons and Mouse Brain Tissues

Oxidative stress in organisms is a factor leading to a series of diseases including tumors and neurological disorders, while methionine sulfoxide reductases (Msrs) may provide an antioxidant and self-repair mechanism through redox cycles of methionine residues in proteins. Thus, it is important to understand the crucial role of Msrs in maintaining the redox homeostasis. However, it remains a great challenge for real-time and quantitative monitoring of Msrs in live systems due to the lack of appropriate sensing tools. Herein, a novel unimolecular platform integrating the intramolecular charge transfer (ICT) and Förster resonance energy transfer (FRET) dual mechanisms was successfully developed. By employing the highly specific Msrs-catalyzed reduction from the electron-withdrawing sulfoxide moiety in the probe to an electron-donating sulfide group, a synergistic ICT-FRET activation process was achieved, leading to a ratiometric fluorescence response toward Msrs with high selectivity, sensitivity, and accuracy. Moreover, benefiting from the favorable features, including mitochondria-targeting, near-infrared two-photon excitation, low cytotoxicity, good stability, and biocompatibility, the probe was successfully used for monitoring mitochondrial Msrs levels in live-neurons, and a positively correlated up-regulation of endogenous Msrs levels under O₂^•- stimulation was observed for the first time, confirming a Msrs-involved adaptive antioxidant mechanism in neurons. Furthermore, two-photon microscopic imaging of various regions in Alzheimer's disease (AD) mice brains revealed a down-regulated Msrs levels compared with that in normal brains, especially in the cornuammonis of the hippocampus region, which may in turn lead to an aggravation of AD pathogenesis due to the weakened antioxidant and self-repair capability of neurons.

Aminoquinoline-anchored polynorbornene for sequential fluorescent sensing of Zn2+ and ATP

A novel aminoquinoline functionalized norbornene (1) and its ring-opening metathesis polymerization (ROMP) copolymer P1 have been designed and synthesized. The polymer probe P1 can self-assemble nano aggregation in aqueous solution. The fluorescent experiments revealed that both 1 and P1 show a ratiometric fluorescence response toward Zn²⁺ over other mental ions in Tris-HCl buffer solution, with the polymer probe P1 shows a better photostability and higher binding affinity than that of the small molecular probe 1. Furthermore, the in situ formed P1-Zn²⁺ ensemble was successfully used as the secondary sensor for ATP. P1 is also successfully used for monitoring intracellular Zn²⁺ and ATP in living cells.