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The development of fluorescent molecular imprinting sensors for direct, rapid, and sensitive detection of small organic molecules in aqueous systems has always presented a significant challenge in the field of detection. In this study, we successfully prepared a hydrophilic colloidal molecular imprinted polymer (MIP) with 2,4-dichlorophenoxyacetic acid (2,4-D) using a one-pot approach that incorporated polyglycerol methacrylate (PGMMA-TTC), a hydrophilic macromolecular chain transfer agent, to mediate reversible addition-fragmentation chain transfer precipitation polymerization (RAFTPP). To simplify the polymerization process while achieving ratiometric fluorescence detection, red fluorescent CdTe quantum dots (QDs) and green fluorescent nitrobenzodiazole (NBD) were introduced as fluorophores (with NBD serving as an enhancer to the template and QDs being inert). This strategy effectively eliminated background noise and significantly improved detection accuracy. Uniform-sized MIP microspheres with high surface hydrophilicity and incorporated ratiometric fluorescent labels were successfully synthesized. In aqueous systems, the hydrophilic ratio fluorescent MIP exhibited a linear response range from 0 to 25 μM for the template molecule 2,4-D with a detection limit of 0.13 μM. These results demonstrate that the ratiometric fluorescent MIP possesses excellent recognition characteristics and selectivity towards 2,4-D, thus, making it suitable for selective detection of trace amounts of pesticide 2,4-D in aqueous systems. [ABSTRACT FROM AUTHOR]

Sequential NanoPrecipitation (SNaP) is a nascent controlled precipitation process for the tunable formation of polymeric particles for drug delivery and bioimaging. While SNaP utilizes the same self‐assembly principles as one‐step Flash NanoPrecipitation, SNaP is a two‐step assembly process in which the particle core formation is initiated during a first mixing step followed by particle stabilization in a second mixing step. Current SNaP experimental set‐ups use commercial millifluidic mixers connected in series, which have several limitations, including the inability to access short inter‐mixer delay times (Td). A robust, 3D‐printed, modular mixer design that enables access to short Td's (〈 25 ms) not previously accessible is reported. For the first time, it is demonstrated that decoupling the assembly steps improves control over particle size, expanding the attainable size range to include both nanoparticles and microparticles. It is empirically proven that inter‐mixer Td is a key parameter for particle size control and that particle size scales with Td in agreement with Smoluchowski's model of diffusion‐limited growth. The formation of particles ranging in size from 160 nm to 1.2 µm is shown. Finally, the applicability of the new mixers is established by encapsulating fluorophores and therapeutics into particles for the first time via SNaP. [ABSTRACT FROM AUTHOR]

Heterogeneity in the fluorescence of carbon dots (CDs) has been hard to figure out so far. This could potentially be related to structural factors, size or intermediate fluorophores, especially when employing the bottom‐up synthesis. Herein, we unveil the origin of fluorescence and spectral heterogeneity of CDs using a simple dynamic method. This work reports the room light‐excited green fluorescence and dual‐emissive N‐doped CDs synthesized using a hydrothermal method. Studies were carried out considering the factors of fluorescence phenomena, such as excitation‐independent emission, fluorescent impurities, aggregation and solvation dynamics. The new steady‐state, Excitation‐resolved area‐normalized emission spectroscopy (ERANES) and ensemble measurements, including time‐resolved studies reveal that a heterogeneous environment exists in the ground state. Eventually, the results show the existence of core, edge and surface states in the CDs. Additionally, the fluorescence characteristics depend on the structural functionalization that occurs in both the intrinsic and extrinsic states of the CDs and it is proven that this does not violate the Kasha‐Vavilov rule. Although a highly purified material could still exhibit heterogeneity due to the ensemble emissive states and structural variations. Our results provide insights into the enduring debates about fluorescence and a deeper understanding of the structure‐ property relationship of CDs. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fluorescent imaging and biosensing in the near‐infrared‐II (NIR‐II) window holds great promise for non‐invasive, radiation‐free, and rapid‐response clinical diagnosis. However, it's still challenging to develop bright NIR‐II fluorophores. In this study, we report a new strategy to enhance the brightness of NIR‐II aggregation‐induced emission (AIE) fluorophores through intramolecular electrostatic locking. By introducing sulfur atoms into the side chains of the thiophene bridge in TSEH molecule, the molecular motion of the conjugated backbone can be locked through intramolecular interactions between the sulfur and nitrogen atoms. This leads to enhanced NIR‐II fluorescent emission of TSEH in both solution and aggregation states. Notably, the encapsulated nanoparticles (NPs) of TSEH show enhanced brightness, which is 2.6‐fold higher than TEH NPs with alkyl side chains. The in vivo experiments reveal the feasibility of TSEH NPs in vascular and tumor imaging with a high signal‐to‐background ratio and precise resection for tiny tumors. In addition, polystyrene nanospheres encapsulated with TSEH are utilized for antigen detection in lateral flow assays, showing a signal‐to‐noise ratio 1.9‐fold higher than the TEH counterpart in detecting low‐concentration antigens. This work highlights the potential for developing bright NIR‐II fluorophores through intramolecular electrostatic locking and their potential applications in clinical diagnosis and biomedical research. [ABSTRACT FROM AUTHOR]

H5, H7, and H9 are pivotal avian influenza virus (AIV) subtypes that cause substantial economic losses and pose potential threats to public health worldwide. In this study, a novel triplex fluorescence reverse transcription-loop-mediated isothermal amplification (TLAMP) assay was developed in which traditional LAMP techniques were combined with probes for detection. Through this innovative approach, H5, H7, and H9 subtypes of AIV can be simultaneously identified and differentiated, thereby offering crucial technical support for prevention and control efforts. Three primer sets and composite probes were designed based on conserved regions of the haemagglutinin gene for each subtype. The probes were labelled with distinct fluorophores at their 3' ends, which were detached to release the fluorescence signal during the amplification process. The detection results were interpreted based on the colour of the TLAMP products. Then, the reaction conditions were optimized, and three primer sets and probes were combined in the same reaction system, resulting in a TLAMP detection assay for the differential diagnosis of AIV subtypes. Sensitivity testing with in vitro-transcribed RNA revealed that the detection limit of the TLAMP assay was 205 copies per reaction for H5, 360 copies for H7, and 545 copies for H9. The TLAMP assay demonstrated excellent specificity, no cross- reactivity with related avian viruses, and 100% consistency with a previously published quantitative polymerase chain reaction (qPCR) assay. Therefore, due to its simplicity, rapidity, sensitivity, and specificity, this TLAMP assay is suitable for epidemiological investigations and is a valuable tool for detecting and distinguishing H5, H7, and H9 subtypes of AIV in clinical samples. [ABSTRACT FROM AUTHOR]

Fluorescence spectroscopy serves as an ultrasensitive sophisticated tool where background noises which serve as a major impediment to the detection of the desired signals can be safely avoided for detections down to the single-molecule levels. One such way of bypassing background noise is plasmon-enhanced fluorescence (PEF), where the interactions of fluorophores at the surface of metals or plasmonic nanoparticles are probed. The underlying condition is a significant spectral overlap between the localized surface plasmon resonance (LSPR) of the nanoparticle and the absorption or emission spectra of the fluorophore. The rationale being the coupling of the excited state of the fluorophore with the localized surface plasmon leads to an augmented emission, owing to local field enhancement. It is manifested in enhanced quantum yields concurrent with a decrease in fluorescence lifetimes, owing to an increase in radiative rate constants. This improvement in detection provided by PEF allows a significant scope of expansion in the domain of weakly emitting fluorophores which otherwise would have remained unperceivable. The concept of coupling of weak emitters with plasmons can bypass the problems of photobleaching, opening up avenues of imaging with significantly higher sensitivity and improved resolution. Furthermore, amplification of the emission signal by the coupling of free electrons of the metal nanoparticles with the electrons of the fluorophore provides ample opportunities for achieving lower detection limits that are involved in biological imaging and molecular sensing. One avenue that has attracted significant attraction in the last few years is the fast, label-free detection of bio-analytes under physiological conditions using plasmonic nanoparticles for point-of-care analysis. This review focusses on the applications of plasmonic nanomaterials in the field of biosensing, imaging with a brief introduction on the different aspects of LSPR and fabrication techniques. [ABSTRACT FROM AUTHOR]

Photochromic circularly polarized luminescence (CPL) demonstrates broad application prospects in the field of advanced functional materials. However, the current photochromic CPL focuses predominantly on single‐band CPL adjustment, and how to achieve dynamically tunable CPL in multi‐band is still highly challenging. This work reports the success in utilizing reversible photochromism for realizing full‐color CPL emission. Photochromic flexible films are created consisting of triple components: spiropyran (SP) working as photochromic matter, polyurethane (PU) as matrix, and chiral helical polyacetylene as chiral component. Further introducing blue fluorophore 9‐anthracene carboxylic acid (ACA) in the film, blue CPL and red CPL are emitted respectively through selective absorption/transmission and circularly polarized fluorescence energy transfer (CPF‐ET). Doping the photochromic film with diverse fluorophores provides full‐color CPL emission. Adding Zn2+ further intensifies fluorescence and CPL via forming merocyanine (MC)‐Zn2+ complex. Taking advantage of the diverse fluorescence and CPL emission, anti‐counterfeiting, and secondary encryption application of the resulting photochromic CPL materials are demonstrated. [ABSTRACT FROM AUTHOR]

The traditional design strategy for constructing highly bright solid‐state luminescent materials relies on incorporating aggregation‐induced emission (AIE) scaffolds, molecular rotors, or bulky substituents to prevent close cofacial packing, which limits the strategy diversity in developing new materials. Herein, a strategy of tuning molecular packing by twisting molecular structure of conventional aggregation‐caused quenching fluorophore is proposed to endow materials with AIE effect and enhance the solid‐state fluorescence. Accordingly, a series of 1,4‐bis(diphenylamino)‐2,5‐disubstituted benzene fluorophores exhibiting AIE characteristics, high solid‐state fluorescence efficiency (up to 0.99), wide emission color tunability, and good near‐infrared (NIR) two‐photon absorption is facilely developed. All these luminogens can specifically stain intracellular lipid droplets with a high signal‐to‐noise ratio, high biocompatibility, and good photostability. Besides, the luminogens exhibit effective reactive oxygen species (ROS) generation capability upon low‐power white light irradiation. Among them, the AIE luminogen, named BDBDC, integrating the NIR emission, good NIR two‐photon absorption and strongest ROS generation demonstrates superior performances in two‐photon fluorescence imaging of various tissues and photodynamic cancer therapy. This molecular design philosophy provides a new way of designing highly bright solid‐state fluorophores for practical applications. [ABSTRACT FROM AUTHOR]

Single‐molecule localization microscopy (SMLM) based on temporal‐focusing multiphoton excitation (TFMPE) and single‐wavelength excitation is used to visualize the three‐dimensional (3D) distribution of spontaneously blinking fluorophore‐labeled subcellular structures in a thick specimen with a nanoscale‐level spatial resolution. To eliminate the photobleaching effect of unlocalized molecules in out‐of‐focus regions for improving the utilization rate of the photon budget in 3D SMLM imaging, SMLM with single‐wavelength TFMPE achieves wide‐field and axially confined two‐photon excitation (TPE) of spontaneously blinking fluorophores. TPE spectral measurement of blinking fluorophores is then conducted through TFMPE imaging at a tunable excitation wavelength, yielding the optimal TPE wavelength for increasing the number of detected photons from a single blinking event during SMLM. Subsequently, the TPE fluorescence of blinking fluorophores is recorded to obtain a two‐dimensional TFMPE‐SMLM image of the microtubules in cancer cells with a localization precision of 18±6 nm and an overall imaging resolution of approximately 51 nm, which is estimated based on the contribution of Nyquist resolution and localization precision. Combined with astigmatic imaging, the system is capable of 3D TFMPE‐SMLM imaging of brain tissue section of a 5XFAD transgenic mouse with the pathological features of Alzheimer's disease, revealing the distribution of neurotoxic amyloid‐beta peptide deposits. [ABSTRACT FROM AUTHOR]

Fluorophores bearing cationic pendants, such as the pyridinium group, tend to preferentially accumulate in mitochondria, whereas those with pentafluorophenyl groups display a distinct affinity for the endoplasmic reticulum. In this study, we designed fluorophores incorporating pyridinium and pentafluorophenyl pendants and examined their impact on sub‐cellular localization. Remarkably, the fluorophores exhibited a notable propensity for the mitochondrial membrane. Furthermore, these fluorophores revealed dual functionality by facilitating the detection of viscosity changes within the sub‐cellular environment and serving as heavy‐atom‐free photosensitizers. With easy chemical tunability, wash‐free imaging, and a favorable signal‐to‐noise ratio, these fluorophores are valuable tools for imaging mitochondria and investigating their cellular processes. [ABSTRACT FROM AUTHOR]

pH has been considered one of the paramount factors in bodily functions because most cellular tasks exclusively rely on precise pH values. In this context, the current techniques for pH sensing provide us with the futuristic insight to further design therapeutic and diagnostic tools. Thus, pH‐sensing (electrochemically and optically) is rapidly evolving toward exciting new applications and expanding researchers' interests in many chemical contexts, especially in biomedical applications. The adaptation of cutting‐edge technology is subsequently producing the modest form of these biosensors as wearable devices, which are providing us the opportunity to target the real‐time collection of vital parameters, including pH for improved healthcare systems. The motif of this review is to provide insight into trending tech‐based systems employed in real‐time or in‐vivo pH‐responsive monitoring. Herein, we briefly go through the pH regulation in the human body to help the beginners and scientific community with quick background knowledge, recent advances in the field, and pH detection in real‐time biological applications. In the end, we summarize our review by providing an outlook; challenges that need to be addressed, and prospective integration of various pH in vivo platforms with modern electronics that can open new avenues of cutting‐edge techniques for disease diagnostics and prevention. [ABSTRACT FROM AUTHOR]

Lipid conjugates have advanced the field of lipid-based nanomedicine by promoting active-targeting (ligand, peptide, antibody), stability (PEGylation), controlled release (lipoid prodrug), and probe-based tracking (fluorophore). Recent findings indicate lipid conjugates dissociating from nanomedicine upon encountering a biological environment. Yet, implications for (pre)clinical outcomes remain unclear. In this study, using the zebrafish model (Danio rerio), we investigated the fate of liposome-incorporated lipid fluorophore conjugates (LFCs) after intravenous (IV) administration. LFCs having a bilayer mismatch and relatively polar fluorophore revealed counter-predictive outcomes for Caelyx/Doxil (clearance vs. circulating) and AmBisome-like liposomes (scavenger endothelial cell vs. macrophage uptake). Findings on LFC (mis)match for Caelyx/Doxil-like liposomes were supported by translational intravital imaging studies in mice. Importantly, contradicting observations suggest to originate from LFC dissociation in vivo , which was investigated by Asymmetric Flow Field-Flow Fractionation (AF4) upon liposome-serum incubation in situ. Our data suggests that LFCs matching with the liposome bilayer composition – that did not dissociate upon serum incubation – revealed improved predictive outcomes for liposome biodistribution profiles. Altogether, this study highlights the critical importance of fatty acid tail length and headgroup moiety when selecting lipid conjugates for lipid-based nanomedicine. [Display omitted] [ABSTRACT FROM AUTHOR]

The aggregation-caused quenching (ACQ) rationale has been employed to improve the fluorescence imaging accuracy of nanocarriers by precluding free probe-derived interferences. However, its usefulness is undermined by limited penetration and low spatiotemporal resolution of NIR-I (700–900 nm) bioimaging owing to absorption and diffraction by biological tissues and tissue-derived autofluorescence. This study aimed to develop ACQ-based NIR-II (1000–1700 nm) probes to further improve the imaging resolution and accuracy. The strategy employed is to install highly planar and electron-rich julolidine into the 3,5-position of aza-BODIPY based on the larger substituent effects. The newly developed probes displayed remarkable photophysical properties, with intense absorption centered at approximately 850 nm and bright emission in the 950–1300 nm region. Compared with the NIR-I counterpart P2, the NIR-II probes demonstrated superior water sensitivity and quenching stability. ACQ1 and ACQ6 exhibited more promising ACQ effects with absolute fluorescence quenching at water fractions above 40% and higher quenching stability with less than 2.0% fluorescence reillumination in plasma after 24 h of incubation. Theoretical calculations verified that molecular planarity is more important than hydrophobicity for ACQ properties. Additionally, in vivo and ex vivo reillumination studies revealed less than 2.5% signal interference from prequenched ACQ1, in contrast to 15% for P2. Novel aggregation-caused quenching (ACQ) probes with bright NIR-II fluorescence were developed by incorporating highly planar and electron-rich julolidine at the 3,5-position of aza-BODIPY, improving the fluorescence imaging accuracy of nanocarriers. [Display omitted] [ABSTRACT FROM AUTHOR]

As advanced oxidation processes (AOPs) is considered to be a highly effective approach for degrading organic pollutants, the simultaneous coagulation and oxidation process by the Fenton‐like reaction of nanoscale zero‐valent iron (NZVI) and hydrogen peroxide (H2O2) is investigated to eliminate the harmful cyanobacterium Microcystis aeruginosa in this study, and the process conditions are optimized using the central composite design of response surface methodology (RSM); in addition, the removal efficiency of M. aeruginosa (in terms of chlorophyll a, Chl a) and the verifications of the antioxidant abilities, as well as extracellular organic matters (EOM) and intracellular organic matters (IOM) are investigated under the optimized conditions. Results indicate that H2O2 concentration is the key factor affecting the Chl a removal efficiency, and the maximum Chl a removal reaches 98.10% under the optimized conditions: NZVI concentration 62.82 mg L−1, H2O2 concentration 54.2 mmol L−1, pH 4.38 and rotating speed 67 rpm. The high correlation coefficient (R2 > 0.80) of analysis of variance (ANOVA) demonstrates the RSM model is extremely significant and suitable for experimental results. Moreover, the total organic carbon (TOC) and fluorescent substances (soluble cyanobacteria metabolic byproducts, aromatic proteins II, humic and fulvic acid‐like compounds) for both EOM and IOM are enhanced removal. It is speculated the removal mechanisms of the Fenton‐like process of NZVI/H2O2 for cyanobacterium belongs to the combined actions of the oxidation of Fe(II)/H2O2 and the coagulation of Fe(III), which destroy the defense system and result in the removal of M. aeruginosa. [ABSTRACT FROM AUTHOR]

Microbial bioaugmentation of coal is considered as a viable and ecologically sustainable approach for the utilization of low-rank coals (LRC). The search for novel techniques to derive high-value products from LRC is currently of great importance. In response to this demand, endeavors have been undertaken to develop microbially based coal solubilization and degradation techniques. The impact of supplementing activated sludge (AS) as a microbial augmentation to enhance LRC biodegradation was investigated in this study. The LRC and their biodegradation products were characterized using the following methods: excitation-emission Matrices detected fluorophores at specific wavelength positions (O, E, and K peaks), revealing the presence of organic complexes with humic properties. FTIR indicated the increased amount of carboxyl groups in the bioaugmented coals, likely due to aerobic oxidation of peripheral non-aromatic structural components of coal. The bacterial communities of LRC samples are primarily composed of Actinobacteria (up to 36.2%) and Proteobacteria (up to 25.8%), whereas the Firmicutes (63.04%) was the most abundant phylum for AS. The community-level physiological profile analysis showed that the microbial community AS had high metabolic activity of compared to those of coal. Overall, the results demonstrated successful stimulation of LRC transformation through supplementation of exogenous microflora in the form of AS. [ABSTRACT FROM AUTHOR]

The impact of the polymeric matrix on the photophysical characteristics of monomeric dyes responsive to excited‐state intramolecular proton transfer (ESIPT) was investigated through UV–Vis absorption as well as steady‐state and time‐resolved emission spectroscopies. For this purpose, two benzoxazole monomers (M1 and M2) with acryloyl groups at different positions in their molecular structures were employed to facilitate covalent bonding within a styrene chain. Our findings reveal significant variations in their excited‐state properties due to the proximity of the acryloyl groups, which affects the energy barrier of the ESIPT reaction, the emission wavelength, and the balance between the normal and tautomeric forms. The experimental results were corroborated through theoretical investigations at the DFT/TDDFT level, specifically using the B3LYP‐D3/def2‐TZVP methodology. Three notable observations emerged: donor/acceptor groups at the meta/para positions induced electron distribution changes, causing red‐shifted emission for M2; in the polymer film, particularly in PM1, intramolecular hydrogen bond deactivation favored N* emission over T* emission; and the zwitterionic character of the T* species. This study underscores the advantages of functionalization in polymers, which can lead to colorless films and prevalent N* or T* emission, and contributes valuable insights into molecular design strategies for tailoring the photophysical properties of polymeric materials. [ABSTRACT FROM AUTHOR]

A series of novel near-infrared (NIR) xanthene-chalcone fluorophores were constructed through a modular synthesis with the electron-donating xanthene moiety and the electron-withdrawing chalcone moiety. These fluorophores are convenient for fluorescence imaging in living cells, benefiting from their NIR emissions (650–710 nm), large Stokes shifts (>100 nm), moderate quantum yields and low cytotoxicity. The substituted hydroxyl group of the xanthene-chalcone fluorophore HCA-E facilitates the development of multifunctional fluorescent probes. As an example, a highly sensitive and selective probe N-HCA-E for glutathione (GSH) detection was developed based on the fluorophore HCA-E. A 4-nitrobenzenesulfonyl (4-Ns) group was introduced to cage the hydroxyl group of HCA-E, which was used as a selective recognition site for the thiol of GSH and an effective fluorescence quencher. Probe N-HCA-E revealed NIR "turn-on" fluorescence (709 nm) for endogenous and exogenous GSH detection in lysosomes with a large Stokes shift (129 nm) and high anti-interference ability. [ABSTRACT FROM AUTHOR]

Polymethine dyes of tetraanionic nature comprising 1,3,2‐dioxaborine rings in the polymethine chain and end‐groups of different electron‐accepting abilities have been synthesized. They can be considered as oligomeric polymethines, where a linear conjugated π‐system passes through three 1,3,2‐dioxaborine units and a number of tri‐ and dimethine π‐bridges between two end‐groups. The obtained dyes exhibit near‐infrared absorption and fluorescence, with molar absorption coefficients reaching as high as 564000 M−1 cm−1 in DMF, rendering them among the strongest absorbers known. The novel compounds are bright NIR fluorophores, with fluorescence quantum yields up to 0.13 in DMF. A comparative analysis of the electronic structure of the obtained dyes with respective dianionic and trianionic oligomers was conducted through quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Organic radicals with narrow energy gaps are highly sought‐after for the production of near‐infrared (NIR) fluorophores. However, the current repertoire of developed organic radicals is notably limited, facing challenges related to stability and low fluorescence efficiency. This study addresses these limitations by achieving stable radicals in nonconjugated poly(diphenylmethane) (PDPM). Notably, PDPM exhibits a well‐balanced structural flexibility and rigidity, resulting in a robust intra‐/inter‐chain through‐space conjugation (TSC). The stable radicals within PDPM, coupled with strong TSC, yield a remarkable full‐spectrum emission spanning from blue to NIR beyond 900 nm. This extensive tunability is achieved through careful adjustments of concentration and excitation wavelength. The findings highlight the efficacy of polymerization in stabilizing radicals and introduce a novel approach for developing nonconjugated NIR emitters based on triphenylmethane subunits. [ABSTRACT FROM AUTHOR]

The combination of fluorogenic probes (fluorogens) and self‐labeling protein tags represent a promising tool for imaging biological processes with high specificity but it requires the adequation between the fluorogen and its target to ensure a good activation of its fluorescence. In this work, we report a strategy to develop molecular rotors that specifically target HaloTag with a strong enhancement of their fluorescence. The divergent design facilitates the diversification of the structures to tune the photophysical and cellular properties. Four bright fluorogens with emissions ranging from green to red were identified and applied in wash‐free live cell imaging experiments with good contrast and selectivity. A HaloTag mutant adapted from previous literature reports was also tested and shown to further improve the brightness and reaction rate of the most promising fluorogen of the series both in vitro and in cells. This work opens new possibilities to develop bright chemogenetic reporters with diverse photophysical and biological properties by exploring a potentially large chemical space of simple dipolar fluorophores in combination with protein engineering. [ABSTRACT FROM AUTHOR]

Photocages, also known as photoactivated protective groups (PPGs), have been utilized to achieve controlled release of target molecules in a non-invasive and spatiotemporal manner. In the past decade, BODIPY fluorophores, a well-established class of fluorescent dyes, have emerged as a novel type of photoactivated protective group capable of efficiently releasing cargo species upon irradiation. This is due to their exceptional properties, including high molar absorption coefficients, resistance to photochemical and thermal degradation, multiple modification sites, favorable uncaging quantum yields, and highly adjustable spectral properties. Compared to traditional photocages that mainly absorb UV light, BODIPY-based photocages that absorb visible/near-infrared (Vis/NIR) light offer advantages such as deeper tissue penetration and reduced bio-autofluorescence, making them highly suitable for various biomedical applications. Consequently, different types of photoactivated protective groups based on the BODIPY skeleton have been established. This highlight provides a comprehensive overview of the strategies employed to construct BODIPY photocages by substituting leaving groups at different positions within the BODIPY fluorophore, including the meso-methyl position, boron position, 2,6-position, and 3,5-position. Furthermore, the application of these BODIPY photocages in biomedical fields, such as fluorescence imaging and controlled release of active species, is discussed. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of terminal donors on the structures and photophysical properties, four donor (D1)-acceptor (A)-π bridge-donor (D2) prototype fluorophores were synthesized and characterized. Single crystal analysis indicated that changing the types of terminal donors (D2) would give rise to different frontier molecular orbitals and molecular packing modes, leading to their different emission behaviors in solid states. In dilute solution, the four D–A–π-D compounds displayed different absorption and emission behaviors in dilute solution with solvatochromism properties. Assisted by the quantum chemical calculations and wave function analysis, the essence of optical properties of four compounds were explored. The results indicated that changing the types of terminal donors (D2) can affect the structures and photophysical properties of such donor (D1)-acceptor (A)-π bridge-donor (D2) prototype fluorophores, which provided guidance to design new fluorophores. [ABSTRACT FROM AUTHOR]

A series of triphenylamine-derived fluorescent dyes were attached to a Cu2+-containing MOF (metal-organic framework), denoted as Pm@CuMOF. The molecular structures of these dyes were discussed by the single crystal structures. Their major absorption bands peaked at 410–450 nm, showing emission bands ranging from 556 to 586 nm with emission quantum yields ranging from 8.0 to 15.1%. It was found that the [-N(C2H5)2] group generally improved sensing performance, and the -OH group in the dyes helped the Cu2+ quenching effect. Pm@CuMOF was observed by SEM as nanorods with a width of ~100 nm and a length of 300 nm. Their XRD patterns and N2 adsorption/desorption isotherms were recorded to confirm their porous structure. A low probe loading level of ~4% was determined by TGA result. The CO sensing mechanism was revealed as a Cu2+/Cu+-involved sensing mechanism based on the result of NMR titration, IR, XPS, and EPR. The fluorescence of these triphenylamine-derived dyes was firstly quenched by CuMOF. In contact with CO, Cu2+ was reduced to Cu+, accompanied by the release and fluorescence recovery of the fluorescent dyes, showing emission turn-on effect towards CO gas. Pm@CuMOF showed increased emission intensity at CO level of 0.005% (versus N2), with response times ranging from 123 s to 280 s (depending on various temperatures). Good selectivity was observed over competing alkane gases, with stable emission for at least 5 days, but no linear calibration plots were observed. [ABSTRACT FROM AUTHOR]

Polystyrene has been extensively used in various industries and consumer products, leading to high quantities of waste. In areas with improper waste management, plastic products reach water systems. Various substances can migrate from plastics into water and become part of a fraction, generically named fluorescent dissolved organic matter. The aim of this study is to determine the level of fluorescent organic matter that leaches from polystyrene into lake water samples, which have a relatively high natural organic matter content. Thus, coffee cup lids have been added to triplicate water samples and compared to a control sample, over a period of 3 weeks. Results show that fluorescent substances migrate from plastic into lake water samples. Styrene oligomers, toluene, and phenol derivates have been proposed as substances that potentially leach from polystyrene products. These compounds may have an impact on fluorescence properties of dissolved organic matter, by potentially inhibiting the microbial activity in water or by forming complex compounds. [ABSTRACT FROM AUTHOR]

Coumarins are secondary metabolites made up of benzene and α-pyrone rings fused together that can potentially treat various ailments, including cancer, metabolic, and degenerative disorders. Coumarins are a diverse category of both naturally occurring as well as synthesized compounds with numerous biological and therapeutic properties. Coumarins as fluorophores play a key role in fluorescent labeling of biomolecules, metal ion detection, microenvironment polarity detection, and pH detection. This review provides a detailed insight into the characteristics of coumarins as well as their biosynthesis in plants and metabolic pathways. Various synthetic strategies for coumarin core involving both conventional and green methods have been discussed comparing advantages and disadvantages of each method. Conventional methods discussed are Pechmann, Knoevenagel, Perkin, Wittig, Kostanecki, Buchwald-Hartwig, and metal-induced coupling reactions such as Heck and Suzuki, as well as green approaches involving microwave or ultrasound energy. Various pharmacological applications of coumarin derivatives are discussed in detail. The structural features and conditions responsible for influencing the fluorescence of coumarin core are also elaborated. [ABSTRACT FROM AUTHOR]

Cancer is one of the major noncommunicable diseases, responsible for millions of deaths every year worldwide. Though various cancer detection and treatment modalities are available today, many deaths occur owing to its late-stage detection and metastatic nature. Noninvasive detection using luminescence-based imaging tools is considered one of the promising techniques owing to its low cost, high sensitivity, and brightness. Moreover, these tools are unique and valuable as they can detect even the slightest changes in the cellular microenvironment. To achieve this, a fluorescent probe with strong tumor uptake and high spatial and temporal resolution, especially with high water solubility, is highly demanded. Recently, several water-soluble molecules with emission windows in the visible (400–700 nm), first near-infrared (NIR-I, 700–1000 nm), and second near-infrared (NIR-II, 1000–1700 nm) windows have been reported in literature. This review highlights recently reported water-soluble small organic fluorophores/dyes with applications in cancer diagnosis and therapeutics. We systematically highlight and describe the key concepts, structural classes of fluorophores, strategies for imparting water solubility, and applications in cancer therapy and diagnosis, i.e., theragnostics. We discuss examples of water-soluble fluorescent probes based on coumarin, xanthene, boron–dipyrromethene (BODIPY), and cyanine cores. Some other emerging classes of dyes based on carbocyclic and heterocyclic cores are also discussed. Besides, emerging molecular engineering methods to obtain such fluorophores are discussed. Finally, the opportunities and challenges in this research area are also delineated. [ABSTRACT FROM AUTHOR]

Lipid droplet (LD) degradation provides metabolic energy and important building blocks for various cellular processes. The two major LD degradation pathways include autophagy (lipophagy), which involves delivery of LDs to autolysosomes, and lipolysis, which is mediated by lipases. While abnormalities in LD degradation are associated with various pathological disorders, our understanding of lipophagy is still rudimentary. In this study, we describe the development of a lipophilic dye containing two fluorophores, one of which is pH‐sensitive and the other pH‐stable. We further demonstrate that this "Lipo‐Fluddy" can be used to visualize and quantify lipophagy in living cells, in an easily applicable and protein label‐free approach. After estimating the ability of compound candidates to penetrate LDs, we synthesized several BODIPY and (pH‐switchable) rhodol dyes, whose fluorescence properties (incl. their photophysical compatibility) were analyzed. Of three Lipo‐Fluddy dyes synthesized, one exhibited the desired properties and allowed observation of lipophagy by fluorescence microscopy. Also, this dye proved to be non‐toxic and suitable for the examination of various cell lines. Moreover, a method was developed to quantify the lipophagy process using flow cytometry, which could be applied in the future in the identification of lipophagy‐related genes or in the screening of potential drugs against lipophagy‐related diseases. [ABSTRACT FROM AUTHOR]

It is vital to develop highly efficient non‐doped blue organic light‐emitting diodes (OLEDs) with high color purity and low‐efficiency roll‐off for applications in display and lighting. Herein, two blue D‐A fluorophores TPA‐PO and TPA‐DPO are designed and synthesized, in which phenanthro[9,10‐d]oxazole (PO) acts as the acceptor and triphenylamine as the donor. TPA‐PO and TPA‐DPO display good thermal stability and efficient luminescence efficiency in neat film. Results based on photophysical property and theoretical calculation demonstrate that TPA‐PO and TPA‐DPO possess the hybridized local and charge‐transfer (HLCT) feature, which can utilize the triplet exciton to achieve highly efficient electroluminance (EL). The non‐doped OLEDs with TPA‐PO/TPA‐DPO as pure emissive layer show the uniform EL emission peak at 468 nm, corresponding to CIE coordinates of (0.168, 0.187) and (0.167, 0.167), respectively. The TPA‐DPO‐based non‐doped OLEDs provide the maximum external quantum efficiency (EQE) of 7.99 % and high exciton utility efficiency of 48.4 %~72.6 %. Moreover, the TPA‐DPO‐based device exhibits low‐efficiency roll‐off, still maintaining the EQE of 6.03 % at the high luminance of 5000 cd m−2. Those findings state clearly that PO is a promising building block of blue fluorophore with a potential HLCT feature to be applied in non‐doped OLEDs. [ABSTRACT FROM AUTHOR]

PEGylated 2-(2-(6-(dimethylamino)benzooxazol-2-yl)vinyl)quinolin-8-ol (BQ-mPEG) was synthesized, which exhibited strong fluorescence at 610 nm (φf = 0.11) and a large Stoke's shift (Δλ = 202 nm) in the aqueous solution. The fluorophore displayed a two-photon absorption characteristic and a strong red emission (λem = 625 nm) was observed with NIR (950 nm) irradiation. The feasibility of using BQ-mPEG as a fluorescent imaging reagent suggested that the fluorophore targets mitochondria, and with 950 nm excitation, bright fluorescence images in HeLa live cells were observed. Furthermore, the fluorophore exhibited some advantages of high photostability and pH stability, as well as low cytotoxicity. [ABSTRACT FROM AUTHOR]

Among various hybrid nanomaterials, the combination of plasmonic nanoparticles and fluorophores in a single multifunctional nanoplatform, so‐called plasmophores, has attracted significant attention in different fields such as dark field, fluorescence, and photoacoustic imaging, biosensing, photothermal, and photodynamic therapy. Herein, author report a facile and controlled synthesis route of hybrid nanoplatforms composed of fluorescent gold nanoclusters (GNCs) coupled to plasmonic gold nanorods (GNRs) using controlled silica (SiO2) dielectric spacers of different thicknesses from now on referred to as GNR@SiO2@GNC plasmophores. The results show different degrees of plasmon‐enhanced fluorescence of the GNCs in their plasmophore hybrid system when placed at different distances from the plasmonic cores of the GNRs. On the other hand, these plasmophores show enhanced thermal stability compared to GNRs@CTAB (CTAB, cetyl trimethyl ammonium bromide). This results also demonstrated that upon annealing at elevated temperatures (800–1000 °C), the GNRs in the plasmophores are more thermally stable and robust than the GNRs@CTAB. More surprisingly, despite the commonly reported very low melting temperature of smaller‐size nanocrystals, the GNCs in the plasmophores showed high thermal stability and do not exhibit significant structural changes at elevated temperatures (800–1000 °C). [ABSTRACT FROM AUTHOR]

The photophysical properties of a series of recently synthesized single benzene fluorophores were investigated using ensemble density functional theory calculations. The energetic stability of the ground and excited state species were counterposed against the aromaticity index derived from local vibrational modes. It was found that the large Stokes shift of the fluorophores (up to ca. 5800 cm −1) originates from the effect of electron donating and electron withdrawing substituents rather than π‐delocalization and related (anti‐)aromaticity. On the basis of nonadiabatic molecular dynamics simulations, the absence of fluorescence from one of the regioisomers was explained by the occurrence of easily accessible S 1/S 0 conical intersections below the vertical excitation energy level. It is demonstrated in the manuscript that the analysis of local mode force constants and the related aromaticity index represent a useful tool for the characterization of π‐delocalization effects in π‐conjugated compounds. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive overview of the synthesis and modification of organic fluorophores, which are organic compounds that emit light when excited. It discusses various synthetic reactions used to create these fluorescent molecules, with a focus on transition-metal-catalyzed C–H activation reactions. The article categorizes recent C–H activation reactions and evaluates their advantages and limitations. This information is valuable for researchers and readers interested in the field of organic fluorophores. The document also includes biographical information about the authors, Dr. Tapasi Chand and Dr. Manmohan Kapur. [Extracted from the article]

Droughts are becoming more intense and frequent in the Brazilian semiarid because of El Niño and global climate changes. The Jaguaribe River estuary is a semiarid ecosystem that experiences a reduction in freshwater discharges due to droughts and river damming. The decrease in freshwater fluxes has increased metal availability through the water residence time increase in the Jaguaribe River estuary. Then, this study aimed to evaluate the dissolved organic matter quality and its interaction with metals in the Jaguaribe River estuary after a severe drought period. It was performed through carbon analyses, fluorescence spectroscopy, ultrafiltration technique, and determinations of metals by ICP-MS. Optical analysis showed that the dissolved organic carbon (DOC) was preponderantly composed of terrestrial-derived humic compounds, while the low ratio between the particulate organic carbon (POC) and chlorophyll-a indicated that POC was predominantly phytoplankton-derived. DOC and POC presented non-conservative removal during the estuarine mixing. DOM and dissolved elements were mostly distributed within the LMW fraction and presented a low percentage in the colloidal fraction. Li, Rb, Sr, Mo, and U showed conservative behavior, while Cu, Fe, Cr, and V had non-conservative behavior with a significant positive correlation with DOM, suggesting DOM as a relevant driver of metal availability at the Jaguaribe River estuary even during the rainy season. [ABSTRACT FROM AUTHOR]

The deployment of small‐molecule fluorescent agents plays an ever‐growing role in medicine and drug development. Herein, we complement the portfolio of powerful fluorophores, reporting the serendipitous discovery and development of a novel class with an imidazo[1,2‐a]pyridinium triflate core, which we term PyrAtes. These fluorophores are synthesized in a single step from readily available materials (>60 examples) and display Stokes shifts as large as 240 nm, while also reaching NIR−I emissions at λmax as long as 720 nm. Computational studies allow the development of a platform for the prediction of λmax and λEm. Furthermore, we demonstrate the compatibility of these novel fluorophores with live cell imaging in HEK293 cells, suggesting PyrAtes as potent intracellular markers. [ABSTRACT FROM AUTHOR]

The dynamics of excited‐state charge transfer (CT) in second near‐infrared (NIR‐II) fluorophore proceeds with conformational change that govern fluorescence. Unveiling the relationship between CT dynamics and conformational change in excited state is of great fundamental significance in optimizing NIR‐II fluorescence but remains less explored. This study unveils the pivotal role of large conformational change in promoting the evolution of emissive CT state into nonemissive CT state in NIR‐II fluorophore (CA‐BBT). Spectroscopic and computational results reveal that large conformational rotation/twisting leads to a pronounced increase in the CT character in excited state. This heightened CT character in CA‐BBT enables a rapid evolution of emissive CT state into a nonemissive CT state within 1.4 ps, as observed by ultrafast spectroscopy. Subsequently, this nonemissive state dominates nonradiative decay, resulting in very low NIR‐II fluorescence. Preventing such detrimental evolution by constraining the conformational dynamics of CA‐BBT results in a 10‐fold enhancement of NIR‐II fluorescence, enabling high‐resolution dynamic visualization of vasculature within osteosarcoma. This study offers a profound understanding of the relationship between CT dynamics and conformational changes in NIR‐II fluorescence, presenting innovative perspectives to develop bright NIR‐II fluorophores. [ABSTRACT FROM AUTHOR]

Fluorescent labelling of proteins enables the determination of their spatiotemporal localization but, sometimes, it can perturb their activity, native localization, and functionality. Spot‐tag is a12‐amino acid peptide recognized by a single–domain nanobody and could potentially resolve the issues associated with large fluorescence tags due to its small size. Here, using as an example the microtubule motor CENTROMERIC PROTEIN E–RELATED KINESIN 7.3 (KIN7.3), we introduce the spot–tag for protein labelling in fixed and living plant cells. Spot–tagging and detection by an anti‐spot nanobody of ectopically expressed KIN7.3 did not interfere with its native localization. Most importantly, our spot‐tagging pipeline facilitated the localization of KIN7.3 much more rapidly and likely accurately than labelling with large fluorescent proteins or even immunolocalization approaches. We should, though, note some limitations we have not resolved yet. Spot–tagging is functional only in fixed cells; it is available only as two fluorophores and may create a noisy background during imaging. However, we foresee that, besides the limitations of this method, spot‐tagging will apply to many proteins, offsetting activity perturbations and low photon quantum yields of other protein‐tagging approaches. [ABSTRACT FROM AUTHOR]

Seafood is one of the most traded food commodities in the world. Traditionally, frozen seafood is evaluated using destructive chemical methods, which are complicated and time-consuming. Therefore, this study proposed a noninvasive method for evaluation of frozen seafood, focusing on fluorescence fingerprints (FFs). FFs, also known as an excitation–emission matrix (EEM), refer to an arranged fluorescence spectrum of emission stimulated by different excitation wavelengths. As FFs is a set of fluorescence spectra acquired at consecutive excitation wavelengths, it produces a three-dimensional diagram that is composite fluorescence of every fluorophore, similar to a fingerprint. Compared with conventional fluorescence spectroscopy, the FFs technique can measure complex samples that contain many fluorophores, because it includes emission spectra excited at many different excitation wavelengths. In this review, the applications of FFs technology for nondestructive prediction of seafood quality are summarized. Postmortem metabolism and seafood freshness indices are discussed comprehensively. We have also introduced multidimensional fluorescence imaging, a combination of FFs and imaging techniques for visualizing seafood product quality. Finally, the advantages of the FFs technique for nondestructive evaluation of seafood quality, even at the frozen state, over traditional methods and previous fluorescent spectroscopic techniques are enumerated. [ABSTRACT FROM AUTHOR]

Herein, we report the development of a macromolecular multifunctional imaging tool for biological investigations, which is comprised of an N‐(2‐hydroxypropyl)methacrylamide backbone, iridium‐based luminescent probe, glutamate carboxypeptidase II (GCPII) targeting ligand, and biotin affinity tag. The iridium luminophore is a tris‐cyclometalated complex based on [Ir(ppy)3] with one of its 2‐phenylpyridine ligands functionalized to allow conjugation. Synthesized macromolecular probes differed in the structure of the polymer and content of the iridium complex. The applicability of the developed imaging tools has been tested in flow cytometry (FACS) based assay, laser confocal microscopy, and fluorescence lifetime imaging microscopy (FLIM). The FACS analysis has shown that the targeted iBodies containing the iridium luminophore exhibit selective labelling of GCPII expressing cells. This observation was also confirmed in the imaging experiments with laser confocal microscopy. The FLIM experiment has shown that the iBodies with the iridium label exhibit a lifetime greater than 100 ns, which distinguishes them from typically used systems labelled with organic fluorophores exhibiting short fluorescence lifetimes. The results of this investigation indicate that the system exhibits interesting properties, which supports the development of additional biological tools utilizing the key components (iridium complexes, iBody concept), primarily focusing on the longer lifetime of the iridium emitter. [ABSTRACT FROM AUTHOR]

Global efforts to minimise carbon dioxide emissions are also leading to attempts to use calcined clays (CC) as a partial substitute for cement in concrete. While the hydration mechanism of such CC blended cements is now well understood, the range of effective admixtures like polycarboxylate ethers (PCE) is limited. There are PCE types that promise relatively high effectiveness, but the mechanisms of action are not yet sufficiently understood. For a detailed understanding of the adsorption of such PCEs, spatially resolved studies of the binder were performed using a combination of fluorescence and scanning electron microscopy. In a comparison of two superplasticisers, the investigations have shown different sites of preferred adsorption in a CC blended system and the results can be correlated with flow tests and setting behaviour. The investigations have shown that a certain PCE type has a higher adsorption on CC and other components of a blended system in comparison to other types. LAY DESCRIPTION: Efforts to reduce carbon dioxide emissions globally are driving attempts to use calcined clays as a partial replacement for cement in concrete. Although the hardening mechanism of cements blended with calcined clays is well understood, the range of effective admixtures, such as plastisicing agents, is limited. While some plastisicing agent types show relatively high effectiveness, their mechanisms of action are not yet fully understood. To understand how these plastisicing agents interact with the compounds, fluorescence and scanning electron microscopy has been used to study this interaction. Two different plastisicing agent types have been compared and it was found that they prefer different sites of the compounds to interact with in a blended cement. These results can be correlated with flow tests and setting behaviour. The investigations have shown that one particular type of plastisicing agents has a higher affinity to calcined clay and other components of a blended system compared to other types. [ABSTRACT FROM AUTHOR]

Fluorophores and fluorophores‐based probes or labels can visualize the structures and content fluctuations of biomolecules, and have made great progress in the broad range of biomedicine fields. However, many commercially available fluorophores suffer from small Stokes shift, which results in insufficient signal‐to‐noise ratio and self‐quenching in advanced imaging techniques. Moreover, the small Stokes shift also hinders the application of fluorophores in some complex imaging, such as single‐excitation multicolor imaging. In the past two decades, many effects have been made to enlarge Stokes shift of fluorophores. In this review, we clarified the reasons for the small Stokes shift building on the structural analysis of fluorophores, systematically summarize the methods of structural modification to increase Stokes shift, and present some representative applications of fluorophores with large Stokes shift in imaging and sensing. [ABSTRACT FROM AUTHOR]

Changes in the viscosity of intracellular microenvironments may indicate the onset of diseases like diabetes, blood‐based illnesses, hypertension, and Alzheimer's. To date, monitoring viscosity changes in the intracellular environment remains a challenge with prior work focusing primarily on visible light‐absorbing viscosity sensing fluorophores. Herein, a series of near‐infrared (NIR, 700–1000 nm) absorbing and emitting indolizine squaraine fluorophores (1PhSQ, 2PhSQ, SO3SQ, 1DMASQ, 7DMASQ, and 1,7DMASQ) are synthesized and studied for NIR viscosity sensitivity. 2PhSQ exhibits a very high slope in its Forster‐Hoffmann plot at 0.75 which indicates this dye is a potent viscosity sensor. The properties of the squaraine fluorophores are studied computationally via density functional theory (DFT) and time‐dependent (TD)‐DFT. Experimentally, both steady‐state and time‐resolved emission spectroscopy, absorption spectroscopy, and electrochemical characterization are conducted on the dyes. Precise photophysical tuning is observed within the series with emission maxima wavelengths as long as 881 nm for 1,7DMASQ and fluorescence quantum yields as high as 39.5 and 72.0 % for 1PhSQ in DCM and THF, respectively. The high tunability of this molecular scaffold renders indolizine squaraine fluorophores excellent prospects as viscosity‐sensitive biological imaging agents with 2PhSQ giving a dramatically higher fluorescence quantum yield (from 0.3 to 37.1 %) as viscosity increases. [ABSTRACT FROM AUTHOR]

Amino‐single benzene‐based fluorophores (SBBFs) are representative small‐size fluorescent dyes that have an electron push‐pull structure within the benzene core. In this work, a new library of amino‐SBBFs, which have trifluoroacetyl moiety at the electron‐pushing amine group (named SBBF‐TFA), featuring a variety of methylamines, dimethylamines, as well as acetyl. To explore the SBBF‐TFA library, we conducted (i) library synthesis, (ii) assessment of various photophysical properties in nine different types of organic/aqueous solvents, and (iii) evaluation of cytotoxicity in the HeLa cell line. We believe that our findings provide valuable insights for advancing novel small‐molecule fluorescent probes and materials with diverse applications across pharmacochemical fields. [ABSTRACT FROM AUTHOR]

Gold(I)‐thiolate complexes have served as primary building blocks for diverse Au nanostructure synthesis strategies. A delicate approach to characterize and control Au(I)‐thiolate motif formation and assembly on the surface is needed as it can potentially solve challenges associated with utilizing gold nanomaterials in many applications. Here, the controllable generation of flower‐shaped surface gold nanostructures (FSGNs) is demonstrated by manipulating the formation‐assembly process of Au(I)‐dodecanethiolate motifs within nanoscale surface droplets. The morphology and structure of the resulting Au nanostructures are governed by internal convection flows and interfacial energy, modulated by the nanodroplet composition and substrate wettability. The obtained FSGNs are proven to act as versatile scaffolds for the selective generation of Au spiky nanostars. These FSGNs can also be utilized to functionalize nanodroplet‐based reactors, boosting the fluorescent intensity of Nile red (NR) fluorophores and decomposing NR via catalytic reaction. Remarkably, with FSGN functionalized droplets smaller than a radius of 500 nm, the decomposition rate of NR can reach ≈0.01 s−1. These results highlight a miniaturized, controllable, and automated method for the in situ production of 3D gold nanostructures on substrates, offering prospects for fast surface nanostructure fabrication and efficient environmental pollutant treatment. [ABSTRACT FROM AUTHOR]

Background: Caffeine, a xanthine alkaloid compound, is a stimulant of the central nervous system and is mainly used in the pharmaceutical and food industries. Because caffeine is directly absorbed into the body, Chinese pharmacopeia has high requirements on the quality of caffeine products, and fluorescence has always been an important indicator to measure the quality of caffeine. In this study, a major fluorescent impurity affecting the appearance and purity of caffeine products was isolated for the first time, and the solubility, thermodynamic properties and dissociation constants of this impurity were studied. Results: (i) The fluorescent impurity affecting the appearance and purity of the product was successfully isolated from crude caffeine and theophylline sodium salt, and named as a blue fluorescent substance. The mass purity of the substance was 96.27%, and its structure was determined based on a comprehensive analysis of high‐resolution mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy [hydrogen 1 (1H) NMR, carbon‐13 (13C) NMR, COSY, NOESY, HSQC, HMBC]. (ii) The solubility of blue fluorescent substance in four pure solvents was determined and the thermodynamic properties were calculated. (iii) The dissociation constants of the blue fluorescent substance in water at 298.15 K were determined by UV spectrophotometry. Conclusion: The results provide a theoretical basis for the crystallization separation of the blue fluorescent substance during the industrial production of caffeine, as well as basic data for the green synthesis process of caffeine. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]