Increase In Fluorescence Intensity Research Articles

Carboxylesterase 2-based fluorescent probe with large Stokes shift for differentiating colitis from bowel cancer

Colitis is considered a significant risk factor for the development and progression of colorectal cancer due to excessive inflammation formed as a result of inflammatory bowel disease (IBD), which is linked to colorectal cancer development. Colorectal cancer often lacks overt symptoms in its early stages, leading to late-stage diagnosis in most patients. Therefore, timely diagnosis and differentiation of colitis and colorectal cancer are crucial. This study introduces a novel activatable carboxylesterase 2 (CES2) fluorescent probe, DBF-CES2, consisting of a cationic indolium fluorophore and a CES2-specific benzyl ester recognition group. The probe operates via the intramolecular charge transfer (ICT) mechanism. Upon binding and hydrolysis by CES2, a potent electron-donating hydroxyl group is released, enhancing the ICT effect and increasing fluorescence intensity, emitting red fluorescence light (λem = 680nm). The probe had a large Stokes shift of 167nm and a detection limit as low as 0.70ng/mL. It also had high selectivity, sensitivity, and biocompatibility. Cellular imaging experiments demonstrated that CES2 expression levels in colorectal cancer cells were higher than those in normal cells. The DBF-CES2 probe specifically recognized endogenous CES2 in colorectal cancer cells, promptly distinguishing them from normal cells. In vivo imaging in mice confirmed that the probe could differentiate between colitis and colorectal cancer, allowing for the assessment of the therapeutic effects of two drugs. The synthesized CES2-targeting organic small molecule fluorescent probe DBF-CES2 is a new molecular tool for the early diagnosis of colitis and colorectal cancer-related diseases, holding significant potential in clinical diagnostics.

Styryl dyes for viscosity measurement and detection of pathological processes in mitochondria of living cells using fluorescence lifetime imaging microscopy, a critical study

In the present work, two molecular rotors based on styryl dyes were synthesized and investigated. Both dyes showed significant sensitivity to the viscosity of the medium. Due to their significant positive charge, they efficiently accumulated in mitochondria of living cells. Binding to mitochondria resulted in increased fluorescence intensity and fluorescence lifetime of the dyes, allowing them to be visualized without washing off the unbound dye. We have also shown that the fluorescence lifetime of the studied molecular rotors is determined not only by the viscosity of the medium, but also by interactions with cell components such as proteins and nucleic acids. The present work clearly shows that these interactions do not allow a reliable estimation of viscosity in cell organelles using the synthesized dyes. This compromises the results of previous viscosity studies using molecular rotors at least of the styryl type. Nevertheless, induction of cell apoptosis by benzylviologen led to an increase in brightness and fluorescence lifetime of the dyes, which can be caused by both changes in viscosity and changes in the expression profile of proteins localized in mitochondria and interacting with the dyes. Thus, the obtained styryl dyes, like previously published homologous compounds, cannot be used for viscosity measurements, but can be used for identification of pathological states of the cell.

Dual-mode sensing with L-phenylalanine-stabilized copper nanoparticles: Real-time detection of Fe3+ and pH monitoring

Water-soluble copper nanoparticles stabilized with L-Phenylalanine (L-PCuNPs) were synthesized and characterized for dual sensing of Fe3+ ions and pH levels. These nanoparticles exhibited green fluorescence at 486 nm, which was quenched by Fe3+ ions, resulting in a color shift from colorless to yellow. Additionally, L-PCuNPs showed pH responsiveness, with increased fluorescence intensity as the pH shifted from acidic to basic. Their effectiveness was further validated through analysis of environmental, biological, and food samples, demonstrating their practical utility across diverse real-world applications.

Short Communication: Ultralow Voltage Electrokinetic Particle Trapping in DC-iEK Devices Using 9V Alkaline Batteries as Power Supply.

This contribution describes direct current insulator-based electrokinetic (DC-iEK) microfluidic devices stimulated by 9V alkaline batteries for the trapping of 2-µm diameter fluorescent polystyrene particles. These devices featured two triangular insulating posts within the fluidic channel. Particle trapping was clearly observed at 18V (two 9V batteries connected in series), but only intermittent particle trapping was observed with a single 9V battery. Particle trapping was determined by measuring the increase in relative fluorescence intensity at the gap region between the single pair of triangular posts. Results demonstrate that the use of low stimulating voltages (deemed as ultralow) in DC-iEK systems may be more suitable for accurate and precise electrokinetic characterization of particles-by exhibiting a very well-localized trapping region with negligible particle oscillations therein, respectively-than for high-performance and high-throughput particle manipulation (i.e., concentration, separation, filtering, or isolation).

Multifunctional Optical Sensor for the Comprehensive Detection of Zinc Ions in Cardiovascular Disease.

Cardiovascular diseases (CVDs) are a major global health concern, highlighting the need for effective diagnostic tools. Zinc ions (Zn2+) play a role in CVDs, but their detection is challenging. This study presents a multifunctional optical sensor, HD-Zn, designed to detect Zn2+ in relation to CVDs. We developed a novel fluorescence probe, HD-Zn, by conjugating N,N-di(2-picolyl)ethylenediamine (DPEN) to HD via an amide bond, which results in fluorescence quenching due to photoinduced electron transfer (PeT). Adding Zn2+ significantly increased fluorescence intensity in the near-infrared region (NIR-I). The probe showed a linear response to varying Zn2+ concentrations, with a detection limit of 9.8 nM, appropriate for physiological conditions. Fluorescence imaging in RAW264.7 macrophages indicated lower intracellular Zn2+ levels in foam cells compared to healthy cells, linked to CVDsprogression. In vivo imaging in mouse models showed decreased fluorescence intensity in the aorta with disease progression. Our findings confirm that HD-Zn is a reliable tool for measuring Zn2+ levels in plaques and demonstrate its biosafety for detecting Zn2+ in serum and urine, offering potential for clinical applications in CVDs diagnosis and monitoring.

Binding interaction of sodium benzoate, potassium sorbate and sodium dihydrogen citrate with BSA as food preservatives: in Vitro analysis and computational studies

Advanced glycation end products (AGEs) are obtained intermediate from nonenzymatic reactions between reducing sugars and proteins, lipids, or nucleic acids and it’s associated with diabetic complications. Today, potassium sorbate (PS), sodium citrate (CIT) and sodium benzoate (SB) were widespread used as food preservatives that can easily enter biological matrices. Here, the interaction between glycosylation Bovine Serum Albumin (BSA) and food preservatives individually and combination of two and three was studied by biochemical and simulation analysis. The results revealed that an increase in absorption and fluorescent intensity in all treated groups. The most carbonyl and glycosylated compounds were observed in the treatment with PS and its combined groups with two preservatives. Treatment with three preservatives alone or combination caused a significant increase in red blood cell hemolysis and MDA level (p < 0.05). The results of the in vitro experiments were in line with the docking studies and the interaction of the compounds with albumin was observed in important subdomain of BSA that show the stability of the BSA-ligand complex. Simultaneous treatment and the combination of two or three food preservatives cause their synergistic effect in possible harm to the body. In addition, the molecular docking experiment suggests that Sodium Benzoate, Potassium Sorbate and Sodium Dihydrogen Citrate can interact with BSA.

Conjugated hypercrosslinked polymers for in situ imprinting, selective sorption, and fluorescent turn-on sensing of oxalic acid.

Hypercrosslinked polymer (HCP) is a subclass of porous organic polymer possessing abundant microporosity, tailor-made functionality, and excellent stability. It features low-cost and easily direct knitting synthesis, facilitating the construction of π-conjugated frameworks with fluorescent properties by properly selecting building blocks (BBs) and linkers. Simultaneous imprinting of target molecules into the conjugated HCPs will create selective sorbents and sensors. We prepared several BBs to be polymerized with a terephthaloyl chloride (TCL) linker through Friedel-Crafts acylation in the presence of some imprinting molecules to clarify the best collocation for the advancement of imprinted polymer. With the highest increase in fluorescence intensity (F), the conjugated HCP comprised of dibenzofuran (DBF) and TCL was selected as contact with oxalic acid (OA). The OA-imprinted DBF-TCL (MICHP) was characterized by FTIR-approved structures, amorphous SEM images, TGA degradation at 390°C, blue-shift emission, prolonged lifetime, and aggregation-caused quenching. The increase in F was proportional to OA concentration (0.17-20.0μM, RSD = 1.6%, LOD = 0.03μM) in THF/H2O (pH 7.0) containing MICHP (0.2mg/3mL) and 6.0min equilibrium. The F increase arose from inhibiting the quenching of photo-induced electron transfer because of protonation and association of OA with imprinted cavities. Langmuir-Freundlich isotherm precisely modeled the imprinted cavity affinity for OA with binding sites of 114.5μmol/g and heterogeneity of 0.939. The cavities distinctly recognized OA and malonic acid interferant, presenting imprinting factor (4.76 vs. 1.35), specific sorption ratio (79.0% vs. 25.7%), and relative selectivity coefficient (3.935 vs. 0.779), which sustained the precise measurements of OA in tomato, taro, and urine. This study approved a cheap and easy strategy to implant fluorescent and imprinting functions in HCPs using as sorbent and sensor through Friedel-Crafts acylation of electrophilic crosslinker and nucleophilic BB, especially those with heterocyclics.

Simultaneous and discriminative visualization of endoplasmic reticulum and lysosomes in apoptosis and autophagy using a single fluorescent probe

The interplay of organelles plays indispensable roles in various biological processes, and their precise interactions contribute to a series of biological functions. Therefore, the exploitation of single probes capable of simultaneously visualizing two organelles is significant yet challenging. In this study, a novel fluorescent probe able to visualize both the endoplasmic reticulum (ER) and lysosomes concurrently was utilized to monitor apoptosis and autophagy. Leveraging the photoinduced electron transfer (PET) mechanisms, the probe (named EL) demonstrated distinct variations in fluorescent intensity within solutions of different pH levels, which enables the differentiation of ER and lysosomes due to their diverse pH values. EL was also effective in monitoring apoptosis with a decrease in fluorescent intensity, and it could visualize the increase of fluorescent intensity in autophagy. Consequently, the discrimination of apoptosis and autophagy processes was achieved. The potential applications of EL in visualizing ER and lysosomes and tracking their dynamic changes during various physiological processes are significant, so this probe would prompt the development of physiology and pathology related to ER and lysosomes.

Near-Infrared Visualization of NAD(P)H Dynamics in Live Cells and Drosophila melanogaster Larvae Using a Coumarin-Based Pyridinium Fluorescent Probe.

A near-infrared fluorescent probe, A, was designed by substituting the carbonyl group of the coumarin dye's lactone with a 4-cyano-1-methylpyridinium methylene group and then attaching an electron-withdrawing NADH-sensing methylquinolinium acceptor via a vinyl bond linkage to the coumarin dye at the 4-position. The probe exhibits primary absorption maxima at 603, 428, and 361 nm, and fluoresces weakly at 703 nm. The addition of NAD(P)H results in a significant blue shift in the fluorescence peak from 703 to 670 nm, accompanied by a substantial increase in fluorescence intensity. This spectral shift is attributed to the transformation from an A-π-A-π-D configuration to a D-π-A-π-D pyridinium platform in probe AH, owing to the addition of a hydride from NADH to the electron-accepting quinolinium acceptor producing the electron-contributing 1-methyl-1,4-dihydroquinoline donor in probe AH. This conclusion is supported by theoretical calculations. The probe was utilized to investigate NAD(P)H dynamics under various conditions. In HeLa cells, treatment with glucose or maltose resulted in a substantial elevation in near-infrared emission intensity, suggesting increased NAD(P)H levels. Chemotherapeutic agents including cisplatin and fludarabine at concentrations of 5, 10, and 20 μM brought about a dose-dependent increase in emission intensity, reflecting heightened NAD(P)H levels due to drug-induced stress and cellular damage. In vivo experiments with hatched, starved Drosophila melanogaster larvae were also conducted. The results showed a clear relationship between emission intensity and the levels of NADH, glucose, and oxaliplatin, confirming that the probe can detect variations in NAD(P)H levels in a living organism. Our investigation also demonstrates that NAD(P)H levels are significantly elevated in the cystic kidneys of ADPKD mouse models and human patients, indicating substantial metabolic alterations associated with the disease. This near-infrared emissive probe offers a highly sensitive and specific method for monitoring NAD(P)H levels across cellular, tissue and whole-organism systems. The ability to detect NAD(P)H variations in reaction to varying stimuli, including nutrient availability and chemotherapeutic stress, underscores its potential as a valuable resource for biomedical research and therapeutic monitoring.

Photoinactivation mechanism of hypericin nanoencapsulated in P123 against Microsporum canis.

Aim: To evaluate the photodynamic mechanism of hypericin nanoencapsulated in P123 copolymer micelles against Microsporum canis in vitro.Material & methods: Antifungal susceptibility tests were performed, including the determination of the minimum fungicidal concentration and time-kill curve. Flow cytometry was used to evaluate the internalization of P123-Hyp in conidia and the activation of PDT type I and II mechanisms via the detection of reactive oxygen species (ROS), as well as to assess changes in the cell membrane using propidium iodide (PI) and cell morphology.Results: P123-Hyp-PDT exerted a fungistatic action on fungus, maintaining this action up to 24h after exposure, corroborating the PS internalization results, which showed satisfactory uptake of P123-Hyp from a concentration of 3.125μmol/l. Among the ROS studied, singlet oxygen was detected. Furthermore, the increased fluorescence intensity of PI in treated cells indicated necrotic cell death, while the size and granularity of the cells were also altered.Conclusion: Our results show, for the first time, a proposal for the mechanism of action of P123-Hyp-mediated PDT against M. canis, proving that it has a prolonged action on the fungus through activation of the type II photodynamic pathway, which resulted in disruption of the plasma membrane and cellular alterations.

Repurposing of PSMA-targeted diagnostic and therapeutic agents for the detection and treatment of giant cell tumors of bone.

Giant cell tumor of bone (GCTB) is a rare bone tumor often necessitating surgical intervention, radiation therapy, or treatment with bisphosphonates or denosumab. 99mTc-MDP bone scintigraphy for GCTB has limited specificity, and the relatively high uptake of 18F-FDG in GCTB makes it challenging to differentiate it from other benign bone tumors. More specific detection and treatment modalities for GCTB are needed to enhance patient monitoring and outcomes. Prostate Specific Membrane Antigen (PSMA) is present in the neovasculature of various tumors, yet unexplored in GCTB. PSMA-targeted imaging and radiotherapeutic agents Locametz and Pluvicto are a powerful theranostic pair for detecting and treating PSMA-positive metastatic tumors, including those in bone, and thus have considerable potential to be repurposed for GCTB. This study aimed to determine if the vasculature of GCTB was PSMA-positive and whether targeting it with PSMA-specific agents was feasible. Using bone core samples from 28 GCTB patients and 9 negative controls, we present the first robust detection of PSMA on the tumor vasculature of GCTB. To demonstrate the potential repurposed use of PSMA-targeted agents in detecting and treating GCTB, we used a PSMA-specific fluorescent probe (FAM-C6-1298) as a model for these radiopharmaceutical agents. Incubation of fresh GCTB tissue samples with FAM-C6-1298 showed increased fluorescence intensity compared to controls, indicating successful targeting of PSMA in GCTB tissue. In conclusion, our data established that PSMA is not only present in the tumor vasculature of GCTB patient tissue but can be effectively targeted with repurposed PSMA-specific radiopharmaceuticals for diagnosis and therapy.

A Cell-Based Screening Assay for rRNA-Targeted Drug Discovery.

Worldwide, bacterial antibiotic resistance continues to outpace the level of drug development. One way to counteract this threat to society is to identify novel ways to rapidly screen and identify drug candidates in living cells. Developing fluorescent antibiotics that can enter microorganisms and be displaced by potential antimicrobial compounds is an important but challenging endeavor due to the difficulty in entering bacterial cells. We developed a cell-based assay using a fluorescent aminoglycoside molecule that allows for the rapid and direct characterization of aminoglycoside binding in a population of bacterial cells. The assay involves the accumulation and competitive displacement of a fluorescent aminoglycoside binding probe in Escherichia coli as a Gram-negative bacterial model. The assay was optimized for high signal-to-background ratios, ease of performance for reliable outcomes, and amenability to high-throughput screening. We demonstrate that the fluorescent binding probe shows a decrease in fluorescence with cellular uptake, consistent with RNA binding, and also shows a subsequent increase upon the addition of the positive control neomycin. Fluorescence intensity increase with aminoglycosides was indicative of their relative binding affinities for A-site rRNA, with neomycin having the highest affinity, followed by paromomycin, tobramycin, sisomicin, and netilmicin. Intermediate fluorescence was found with plazomicin, neamine, apramycin, ribostamicin, gentamicin, and amikacin. Weak fluorescence was observed with kanamycin, hygromycin, streptomycin, and spectinomycin. A high degree of sensitivity was observed with aminoglycosides known to be strong binders for the 16S rRNA A-site compared with antibiotics that target other biosynthetic pathways. The quality of the optimized assay was excellent for planktonic cells, with an average Z' factor value of 0.80. In contrast to planktonic cells, established biofilms yielded an average Z' factor of 0.61. The high sensitivity of this cell-based assay in a physiological context demonstrates significant potential for identifying potent new ribosomal binding antibiotics.

Effect of ultrasound combined with plasma protein treatment on the structure, physicochemical and rheological properties of myofibrillar protein

This study aimed to investigate the effect of ultrasound combined with plasma protein (UPP) treatment on the structure, physicochemical and rheological properties of myofibrillar protein (MP). The results indicated that the UPP group caused changes in the secondary structure, increased fluorescence intensity and enhanced surface hydrophobicity of MP. Then, UPP significantly decreased the content of free and total sulfhydryl group, and high molecular weight protein contents were observed in MP. These findings implied moderate cross-linking and aggregation between plasma protein and MP in this ultrasound treatment. Furthermore, the physical characteristics, stability and rheological properties of MP were improved in UPP, as evidenced by increased storage modulus and decreased loss angle tangent. Therefore, this study suggested that the combined treatment not only had the potential to enhance the product quality in the process of ground meat, but also improved the utilization rate and added value of plasma proteins.

Detection of a Water-Soluble Hypericin Formulation in Glioblastoma Tissue with Fluorescence Lifetime and Intensity Using a Dual-Tap CMOS Camera System.

High hypericin-loaded polyvinylpyrrolidone (HHL-PVP) constitutes a novel approach to utilize the promising characteristics of hypericin for photodynamic diagnosis (PDD) and therapy (PDT) of brain tumors in an orally bioavailable formulation. The aim of this study was to investigate the ability of a Complementary Metal-Oxide-Semiconductor (CMOS) camera-based fluorescence imaging system to selectively visualize HHL-PVP in glioblastoma tissue even in the presence of 5-Aminolvevulinic acid (5-ALA) induced fluorescence, which is widely utilized in brain tumor surgery. We applied a previously established system with a non-hypericin specific filter for 5-ALA fluorescence visualization and a newly introduced hypericin-specific filter at 575-615 nm that transmits the spectrum of hypericin, but not 5-ALA fluorescence. Glioblastoma specimens obtained from 12 patients (11 with preoperative 5-ALA intake) were ex vivo incubated with HHL-PVP. Subsequently, fluorescence intensity and lifetime changes using both the non-hypericin specific filter and hypericin-specific filter were measured before and after HHL-PVP incubation and after subsequent rinsing. While no significant differences in fluorescence signal were observed using the non-hypericin specific filter, statistically significant increases in fluorescence intensity (p = 0.001) and lifetime (p = 0.028) after HHL-PVP incubation were demonstrated using the hypericin-specific filter. In consequence, specimens treated with HHL-PVP could be identified according to the fluorescence signal with high diagnostic sensitivity (87.5%) and specificity (100%). Our CMOS camera-based system with a hypericin-specific filter is capable of selectively visualizing hypericin fluorescence in glioblastoma tissue after ex vivo HHL-PVP incubation. In the future, this technique could facilitate clinical investigations of HHL-PVP for PDD and PDT while maintaining the current standard of care with 5-ALA guidance.

Time-resolved observation of DHR123 nano-clay radio-fluorogenic gel dosimeters by photoluminescence-detected pulse radiolysis

The importance of real-time dose evaluation has increased for recent advanced radiotherapy. However, conventional methods for real-time dosimetry using gel dosimeters face challenges owing to the delayed dose response caused by the slow completion of radiation-induced chemical reactions. In this study, a novel technique called photoluminescence-detected pulse radiolysis (PLPR) was developed, and its potential to allow real-time dose measurements using nano-clay radio-fluorogenic gel (NC-RFG) dosimeters was investigated. PLPR is a time-resolved observation method, and enables time-resolved fluorescence measurement. NC-RFG dosimeters were prepared, typically consisting of 100 μM dihydrorhodamine 123 (DHR123) and 2.0 wt.% nano-clay, along with catalytic and dissolving additives. We successfully achieved time-resolved observation of the increase in fluorescence intensity upon irradiation of the dosimeter. Dose evaluation was possible at 1 s after irradiation. The dose-rate effect was not observed for the deoxygenated dosimeter, but was observed for the aerated dosimeter. Besides the dose-rate effect, linear dose responses were obtained for both conditions. Furthermore, we made a novel observation of a decay in the fluorescence intensity over time in the early stages which named fluorescence secondary loss (FSL) and elucidated the conditions under which this phenomenon occurs.

Tailored controllable bifunctional fluorescent-magnetic nanobeads for new generation fast-response immunosensor with dual-signal amplification

Immunosensors based on the fluorescence-linked immunosorbent assay (FLISA) platform are now widely used; however, the long-term response and lower sensitivity limited their development in clinical applications. In this study, we first tailored bifunctional magnetic nanoparticle (MNP)-quantum dot (QD) nanobeads (MQBs) with rapid magnetic response and strong fluorescence intensity for the FLISA platform to construct a fast-response immunosensor. Under optimal conditions, we constructed a dual-signal amplification immunosensor based on an MQB-driven FLISA platform for a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen. We achieved a 29-fold increase in fluorescence intensity over the QD nanobeads (SiO2/QD/SiO2, QBs). Compared with the conventional FLISA platform-based QBs, the sensitivity of the developed immunosensor increased 63-fold to 7.50 pg/mL in half the detection time of common FLISA (only 30 min). More important, the test results of this dual-signal amplification immunosensor showed good specificity and accuracy. This novel MQB magnetic-driven FLISA platform with high throughput, as a proof of concept, effectively improved sensitivity and shortened reaction time. As a result, it is expected to have significant potential in the field of point-of-care testing.

Precision Delivery of Binary Cooperative Nanodrugs Self-Assembled by Berberine Glycyrrhetinic Acid Salts for Hepatocellular Carcinoma Treatment.

Berberine (BB) has demonstrated significant inhibitory effects on tumorigenesis and progression. However, its clinical application is hindered by challenges such as low bioavailability due to limited cell membrane permeability, nontargeted accumulation away from solid tumors, and increased toxicity associated with intravenous administration. To overcome these challenges, a lipophilic salt-forming strategy was employed to enhance lipophilicity, thereby promoting membrane permeability and targetability for tumor accumulation while simultaneously mitigating the toxicity associated with intravenous injection. In vitro findings revealed an almost 10-fold increase in fluorescence intensity with BB-GA NDs compared to BB alone. Furthermore, selective cytotoxicity against tumor cells exhibited a 4-fold elevation compared to normal cells. In vivo results underscored the remarkable tumor-selective accumulation of BB-GA NDs, effectively mitigating the intravenous injection toxicity associated with pure BB. The self-assembly of binary cooperative nanodrugs utilizing berberine glycyrrhetinic acid salts opens up innovative possibilities for drug delivery systems in traditional Chinese medicine.

Green Protocol for the Synthesis of Luminescent Carbon Nanodots Derived from Murraya Koenigii Leaves and Urea: Enhancing Photoluminescence for Advanced Bioimaging.

We have synthesized Murraya Koenigii leaves powder-derived carbon nanodots (CNDs) by hydrothermal method. A tribute to our commitment to environmental sustainability is the unique composition of our CNDs, which are made entirely of natural carbon sources and a green solvent, water. Our further efforts to improve performance led us to start making nitrogen-doped CNDs. By using urea as a non-toxic source of nitrogen, we observed a substantial increase in fluorescence intensity, extending the usefulness and potential of these nanomaterials. We investigated the optical properties using UV-Vis and fluorescence spectroscopy. The other parameters, like structural and size-shape morphology, were analyzed using FTIR, XRD, and HR-TEM, respectively. The fluorescence spectroscopy demonstrated their capability to exhibit wavelength-dependent photoluminescence (PL), highlighting the potential of these CNDs for cell bioimaging applications. The fluorescence properties affirm their suitability for biomedical applications, as they do not involve any inherent risk to cells.

A Turn‐On Fluorescence Probe Based on a New Salamo‐Co (II) Coordination Polymer for Tyrosine Detection and Its Application in Water Samples

ABSTRACTA novel salamo‐Co (II) coordination polymer probe CP was synthesized firstly, and its crystal structure, [Co3(L)2(PTA)(H2O)2]n·4nDMF, was determined by X‐ray diffraction analysis. The probe has a rare aggregation‐induced luminescence enhancement (AIEE) effect. When applied to amino acid detection, it was found to have a high selective recognition of tyrosine. With the increase of tyrosine, the fluorescent strength of the probe was enhanced in a short period of time. In addition, the binding ratio of probe to Tyr was determined by fluorescence titration experiment, and the detection limit LOD of probe CP for Tyr was calculated to be 2.57 × 10−9 M, and the binding constant Ka was 2.96 × 105 M−1. According to UV absorption spectrum, FT‐IR spectra, ESI mass spectrometry, and DFT calculation, it was speculated that Tyr can bind to the probe after adding Tyr into the probe solution, triggering FRET and ICT effects, resulting in increased fluorescence intensity and blue shift, and finally achieving the specific recognition of tyrosine by probe CP. Finally, the practical application of probe CP was studied. Through strip test and real water sample test, it was found that the probe can be used for qualitative and quantitative analysis of tyrosine.

Co-Assembled Nanosystems Exhibiting Intrinsic Fluorescence by Complexation of Amino Terpolymer and Its Quaternized Analog with Aggregation-Induced Emission (AIE) Dye.

Aggregation-induced emission dyes (AIEs) have gained significant interest due to their unique optical properties. Upon aggregation, AIEs can exhibit remarkable fluorescence enhancement. These systems are ideal candidates for applications in bioimaging, such as image-guided drug delivery or surgery. Encapsulation of AIEs in polymeric nanocarriers can result in biocompatible and efficient nanosystems. Herein, we report the fabrication of novel nanoaggregates formulated by amino terpolymer and tetraphenylethylene (TPE) AIE in aqueous media. Poly(di(ethylene glycol) methyl ether methacrylate-co-2-(dimethylamino)ethylmethacrylate-co-oligoethylene glycol methyl ether methacrylate), P(DEGMA-co-DMAEMA-co-OEGMA) hydrophilic terpolymer was utilized for the complexation of the sodium tetraphenylethylene 4,4',4″,4‴-tetrasulfonate AIE dye. Fluorescence spectroscopy, physicochemical studies, and self-assembly in aqueous and fetal bovine serum media were carried out. The finely dispersed nanoparticles exhibited enhanced fluorescence compared to the pure dye. To investigate the role of tertiary amino groups in the aggregation phenomenon, the polymer was quaternized, and quaternized polymer nanocarriers were fabricated. The increase in fluorescence intensity indicated stronger interaction between the cationic polymer analog and the dye. A stronger interaction between the nanoparticles and fetal bovine serum was observed in the case of the quaternized polymer. Thus, P(DEGMA-co-DMAEMA-co-OEGMA) formulations are better candidates for bioimaging applications than the quaternized ones, presenting both aggregation-induced emission and less interaction with fetal bovine serum.