Specific Fluorescence Research Articles

Chemodiversity and Molecular Mechanism Between Per-/Polyfluoroalkyl Substance Complexation Behavior of Humic Substances in Landfill Leachate

Landfill leachate contains a range of organic and inorganic pollutants, including per-/polyfluoroalkyl substances (PFASs), which can infiltrate into surrounding soil and groundwater through leaching processes, and can pose a threat to human health via food chains and drinking water processes. Thus, the transport of PFASs in landfill leachate is a research hotspot in environmental science. This study investigates the complexation and adsorption mechanisms between humic substances and PFASs in landfill leachate at the molecular level. Experimental results demonstrate that the binding constant logKsv of humic substances with PFASs correlates positively with specific ultraviolet absorbance (SUVA254), absorbance ratio (A250/A365), humification index (HIX), and fluorescence index (FI), while it exhibits a negative correlation with the biological index (BIX). These findings indicate that high aromaticity is a prerequisite for molecular interactions between humic substances and PFASs, with polar functional groups further facilitating the interaction. Molecular-level analysis revealed that humic substances undergo complexation and adsorption with PFASs through hydrophobic interactions, van der Waals forces, hydrogen bonding, ionic bonding, and covalent bonding, by functional groups such as hydroxyl, aliphatic C-H bonds, aromatic C=C double bonds, amides, quinones, and ketones. Future efforts should focus on enhanced co-regulation and mitigation strategies addressing the combined pollution of PFASs and humic substances in landfill leachate.

A Turn-On Fluorescence Probe Based on GSH-Protected Silver Nanoclusters for the Selective Detection of Pb2.

Glutathione-protected silver nanoclusters (GSH-AgNCs) with good photostability were successfully synthesized through a one-pot heating process. The resultant GSH-AgNCs with an average diameter of ~1.6 nm exhibit red fluorescence (λem = 650 nm), and the fluorescence is excitation independent. Strong aggregation-induced emission (AIE) effect was observed in GSH-AgNCs, which can be induced by solvent and metal ions. In particular, a specific fluorescence enhancement was detected upon interaction with lead ions (Pb2+). A fluorescent probe was designed for off-on detection of Pb2+ based on as-synthesized GSH-AgNCs. Under the optimum parameters, two linear response intervals were found between the relative fluorescence intensity and the concentration of Pb2+ in the range of 10-250 μM (R2 = 0.9900) and 400-1000 μM (R2 = 0.9930). Significant fluorescence color evolutions observed under UV light, resulting in a semiquantitative visual detection of Pb2+. A possible detection mechanism based on the interaction between GSH-AgNCs and Pb2+ is discussed.

A facile synthesis of polyethyleneimine based fluorescent polymeric nanorods using vitamin B6 cofactor as cross-linker for ratiometric detection of doxorubicin.

Polyethyleneimine (PEI) based fluorescent polymeric nanorods with high quantum yield (87.21%) were synthesized by crosslinking and self-assembly of PEI by vitamin B6 cofactor pyridoxal 5'-phosphate (PLP). The fluorescent PEIPLP polymeric nanorods were employed for the ratiometric detection of doxorubicin (DOX). With the addition of DOX to the PEIPLP nanorods, the fluorescent intensity was decreased at 510nm and concomitantly enhanced at 590nm due to the fluorescence resonance energy transfer (FRET) process. The selective and specific ratiometric fluorescence response from the PEIPLP nanorods can be employed to detect DOX down to 10 nM. Thepractical utility of the PEIPLP nanorods was examined by detecting DOX in human serum.

De Novo Balanced Translocations Disrupting the FBN1 Gene Diagnosed by Genome Sequencing: An Uncommon Cause of Marfan Syndrome Modifying Genetic Counseling.

Marfan syndrome (MFS) is a well-characterized rare genetic connective tissue disorder. The features of MFS are primarily skeletal, ocular, and cardiovascular and are mainly caused by single-nucleotide variants (SNVs) in the FBN1 gene (MIM#134797) located on chromosome 15q21.1. We describe two patients, a 26-year-old male and a 10-year-old female from unrelated distinct families, with clinically diagnosed sporadic MFS. After years of unsuccessful molecular diagnosis for genetic counseling purposes, genome sequencing was performed and revealed a balanced translocation in both patients: de novo t(9;15)(p13.3;q21.1) translocation in the male patient, and de novo t(15;16)(q21.1;p13.13) translocation in the female patient, respectively, disrupting intron 40 and 45 of FBN1. The other breakpoints were not clinically relevant. These translocations were confirmed by specific fluorescence insitu hybridization probes and conventional karyotyping. In the literature, only one family has been described, leading to four cases of MFS caused by balanced translocations. Genetic counseling for balanced translocations differs from SNVs and even interstitial deletions since it is not restricted to MFS recurrence, but also involves the risk of unbalanced gametes, leading to miscarriage or unbalanced progeny. In case of clinical certainty, MFS patients should be screened for balanced translocations to ensure appropriate genetic counseling.

Novel quinoline-based chemosensor as specific fluorescence sensing of copper ions in cancer cells and for organelle-specific imaging application

This work reports a simple synthesis of a quinoline-based organic molecule, (E)-N′-((6-methoxy-2-oxo-1,2-dihydroquinolin-3-yl)methylene) picolinohydrazide (PHMQ), and its ability to distinguish Cu2+ ion. Through the use of spectroscopic and photometric titration techniques, PHMQ’s selectivity toward various cations and anions was examined. In just two minutes, PHMQ showed fast detection of Cu2+ ions, and clear spectral fluctuations proposed persistent PHMQ-Cu2+ complex formation. The calculated emission quenching constant (1.46 × 105 L/mol) and binding constant (1.25 × 104 L/mol) values suggested that strong emission quenching occurs between the PHMQ and Cu2+ ions. A linear reduction in fluorescence response was noted for Cu2+ ions concentrations between 2–26 μM, with a detection limit of 43.4 nM. Job’s plot, ESI-mass, NMR titration experiments, and density functional theory (DFT) simulations established a 1:1 stoichiometry for the PHMQ-Cu2+ complex. Additionally, PHMQ was efficaciously utilized to quantify Cu2+ ions in drinking and tap water samples and HeLa cells, illustrating durable cellular penetrability and a fluorescence ’Turn-Off’ response to Cu2+ ions. This sensor also established usefulness in mitochondrial-targeted imaging. For the detection of Cu2+ ions in biological and environmental environments, PHMQ is a promising detector due to its high sensitivity, selectivity, and quick response.

Intraoperative Guidance of Pancreatic Cancer Resection Using a Toll-like Receptor 2-Targeted Fluorescence Molecular Imaging Agent.

Human TLR2 is broadly expressed among pancreatic adenocarcinomas, and the highly specific TLR2L-800 fluorescence molecular imaging agent has potential for use in fluorescence-guided surgery to increase R0 margins and improve patient survival.

Two-color fluorescence-guided surgery for head and neck cancer resections.

Head and neck squamous cell carcinoma (HNSCC) has the sixth highest incidence worldwide, with cases annually. Surgery is the primary treatment option for HNSCC, during which surgeons balance two main goals: (1)complete cancer resection and (2)preservation of normal tissues to ensure post-surgical quality of life. Unfortunately, these goals are not synergistic, where complete cancer resection is often limited by efforts to preserve normal tissues, particularly nerves, and reduce life-altering comorbidities. Currently, no clinically validated technology exists to enhance intraoperative cancer and nerve recognition. Fluorescence-guided surgery (FGS) has successfully integrated into clinical medicine, providing surgeons with real-time visualization of important tissues and complex anatomy, where FGS imaging systems operate almost exclusively in the near-infrared (NIR, 650 to 900nm). Notably, this spectral range permits the detection of two NIR imaging channels for spectrally distinct detection. Herein, we evaluated the utility of spectrally distinct NIR nerve- and tumor-specific fluorophores for two-color FGS to guide HNSCC surgery. Using a human HNSCC xenograft murine model, we demonstrated that facial nerves and tumors could be readily differentiated using these nerve- and tumor-specific NIR fluorophores. The selected nerve-specific fluorophore showed no significant difference in nerve specificity and off-target tissue fluorescence in the presence of xenograft head and neck tumors. Co-administration of two NIR fluorophores demonstrated successful tissue-specific labeling of nerves and tumors in spectrally distinct NIR imaging channels. We demonstrate a comprehensive FGS tool for cancer resection and nerve sparing during HNSCC procedures for future clinical translation.

Dual-lock-and-key virus-mimicking nanoprobes for ultra-high accurate and sensitive imaging of viral infections in vivo

Fluorescence in situ imaging of viral infection lesions in vivo is crucial for precise diagnosis of viral diseases and evaluation of the extent of viral infection. Nevertheless, achieving highly specific and sensitive fluorescence imaging of viral infection sites in vivo has posed a persistent challenge. Here, we developed a dual-lock-and-key virus-mimicking nanoprobe that consisted of polyamide dendrimers (PAMAM) loaded internally with molecular beacons double-triggered by apurinic/apyrimidinic nucleic acid endonuclease 1 (APE1) and viral RNA (vRNA), and surface-modified with the E protein of Japanese encephalitis virus (JEV). This activatable nanoprobe generated dramatically amplified fluorescent signals stimulated by expressed vRNA and APE1 during viral infection, enabling ultrahigh specific and sensitive imaging of the lesions of JEV infection in vivo. This study provides a potential approach for accurate and sensitive detection of viral infection levels and assessment of the efficacy of antiviral drugs in vivo.

Activatable Near-Infrared Fluorescence Probe for Hypochlorous Acid Detection in Early Diagnosis of Keloids.

Keloids represent pathologic conditions characterized by the presence of hyalinized collagen bundles and chronic inflammatory reactions. Recently, increased ROS production and disrupted apoptosis mechanisms in keloids have been reported, although the detailed mechanisms remain unclear. Herein, we developed a specific fluorescence probe, Pro-NBS, to investigate ClO- levels in keloids. The probe demonstrated high specificity for ClO- over other ROS and exhibited a strong linear detection relationship. Based on its performance, we focused on the TGF-β pathway in the development of keloids. ROS upregulation was observed in keloid-derived fibroblasts. Using ClO- as an intrinsic overexpression marker, our probe effectively distinguished between normal fibroblasts and keloid-derived fibroblasts both in vitro and in vivo. Furthermore, Pro-NBS showed potential for monitoring the progression and evaluating the systematic therapy of abnormal scarring or keloids.

In vivo self-assembled albumin nanoparticle elicit antitumor immunity of PD-1 inhibitor by imaging and clearing tumor-associated macrophages.

Eliciting anti-tumor immune responses and improving the tumor microenvironment crucial for boosting the effectiveness of anti-PD-1 immunotherapy. Tumor-associated macrophages (TAMs), the primary types of immune cells infiltrating tumors, play a critical role in the formation of an immunosuppressive microenvironment. In this study, we constructed a novel Evans Blue (EB)-based in vivo self-assembled nanocarrier system, mUNO-EB-ICG-Fc@Alb nanoparticles (designated as MA NPs), for targeted imaging and clearance of M2-TAMs to elicit antitumor immunotherapy of PD-1 inhibitor. In vitro experiments demonstrated the specific fluorescence imaging and killing effect of MA NPs on M2-TAMs. In vivo experiments shown that MA NPs-induced chemodynamic therapy (CDT) successfully reversed the tumor immunosuppressive microenvironment (ITM), promoted intratumoral infiltration of T lymphocytes, and ultimately enhancing the anti-tumor immunotherapy effect of PD-1 inhibitors. This study might provide good inspiration for improving the therapeutic efficacy of cancer immunotherapy.

Engineering AIEgens-Tethered Gold Nanoparticles with Enzymatic Dual Self-Assembly for Amplified Cancer-Specific Phototheranostics.

Accurate imaging and precise treatment are critical to controlling the progression of pancreatic cancer. However, current approaches for pancreatic cancer theranostics suffer from limitations in tumor specificity and invasive surgery. Herein, a pancreatic cancer-specific phototheranostic modulator (AuHQ) dominated by aggregation-induced emission (AIE) luminogens-tethered gold nanoparticles is meticulously designed to facilitate prominent fluorescence-photoacoustic bimodal imaging-guided photothermal immunotherapy. Once reaching the pancreatic tumor microenvironment (TME), the peptide Ala-Gly-Phe-Ser-Leu-Pro-Ala-Gly-Cys (AGFSLPAGC) linkage within AuHQ can be specifically cleaved by the overexpressed enzyme Cathepsin E (CTSE), triggering the dual self-assembly of AuNPs and AIE luminogens. The aggregation of AuNPs mediated by enzymatic cleavage results in potentiated photothermal therapy (PTT) under near-infrared (NIR) laser irradiation, induced immunogenic cell death (ICD), and enhanced photoacoustic imaging. Simultaneously, AIE luminogen aggregates formed by hydrophobic interaction can generate AIE fluorescence, enabling real-time and specific fluorescence imaging of pancreatic cancer. Furthermore, coadministration of an indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor with AuHQ can address the limitations of PTT efficacy imposed by the immunosuppressive TME and leverage the synergistic potential to activate systemic antitumor immunity. Thus, this well-designed phototheranostic modulator AuHQ facilitates the intelligent enzymatic dual self-assembly of imaging and therapeutic agents, providing an efficient and precise approach for pancreatic cancer theranostics.

Multiplexed bacterial recognition based on “All-in-One” semiconducting polymer dots sensor and machine learning

The accurate discrimination of bacterial infection is imperative for precise clinical diagnosis and treatment. Here, this work presents a simplified sensor array utilizing “All-in-One” Pdots for efficient discrimination of diverse bacterial samples. The “All-in-One” Pdots sensor (AOPS) were synthesized using three components that exhibit fluorescence resonance energy transfer (FRET) effect, facilitating the efficient integration of multiple discrimination channels to generate specific fluorescence response patterns through a single detection under single-wavelength excitation. Additionally, machine learning techniques were employed to visually represent the fluorescence response patterns of AOPS upon exposure to bacterial metabolites derived from diverse bacterial species. The as-prepared sensor platform demonstrated excellent performance in analyzing eight common bacteria, drug-resistant strains, mixed bacterial samples, bacterial biofilms and real samples, presenting significant potential in the identification of complex samples for bacterial analysis.

Neutrophil elastase-activated carbon dots for non-invasive early diagnosis of inflammatory bowel disease by near-infrared-II fluorescence imaging

Most near-infrared-II (NIR-II) fluorescent probes produce an “always-on” output with poor signal specificity for biomarkers. Neutrophil elastase (NE) is a critical factor in chronic inflammation or in the acute response to infection and injury, and NE activatable NIR-II fluorescent probes can aid in the early clinical diagnosis of inflammatory bowel disease (IBD). In this paper, we synthesized OPDG-PFA@PEI carbon dots (CDs) through a two-step reaction of solvothermal/surface covalent bond modification, which can “turn on” specific NIR-II fluorescence signals related to the level of NE produced by neutrophils and target sites of inflammation effectively, thus realizing the monitoring of in-situ NE in cells and in vivo. OPDG-PFA@PEI CDs fluorescent nanoprobe show high-performance real-time non-invasive NIR-II fluorescence imaging for early diagnostic evaluation of IBD in mouse models of DSS-induced IBD, providing a promising approach for the development of clinical non-invasive and more convenient early diagnosis of IBD.

Non-Invasive Endometrial Cancer Screening through Urinary Fluorescent Metabolome Profile Monitoring and Machine Learning Algorithms.

Endometrial cancer is becoming increasingly common, highlighting the need for improved diagnostic methods that are both effective and non-invasive. This study investigates the use of urinary fluorescence spectroscopy as a potential diagnostic tool for endometrial cancer. Urine samples were collected from endometrial cancer patients (n = 77), patients with benign uterine tumors (n = 23), and control gynecological patients attending regular checkups or follow-ups (n = 96). These samples were analyzed using synchronous fluorescence spectroscopy to measure the total fluorescent metabolome profile, and specific fluorescence ratios were created to differentiate between control, benign, and malignant samples. These spectral markers demonstrated potential clinical applicability with AUC as high as 80%. Partial Least Squares Discriminant Analysis (PLS-DA) was employed to reduce data dimensionality and enhance class separation. Additionally, machine learning models, including Random Forest (RF), Logistic Regression (LR), Support Vector Machine (SVM), and Stochastic Gradient Descent (SGD), were utilized to distinguish between controls and endometrial cancer patients. PLS-DA achieved an overall accuracy of 79% and an AUC of 90%. These promising results indicate that urinary fluorescence spectroscopy, combined with advanced machine learning models, has the potential to revolutionize endometrial cancer diagnostics, offering a rapid, accurate, and non-invasive alternative to current methods.

Bifunctional In-MOFs for Selective and Sensitive Detection of Trace Nitrobenzene Compounds in Water and Possessing High Proton Conductivity.

With the escalating prevalence of terrorism and global environmental pollution, nitroaromatic compounds (NACs) have increasingly come into focus as the primary culprit. To counter these challenges, it is imperative to develop simple and efficient methods for detecting NACs. Considering the electron-deficient structure of NAC molecules, this paper constructed a novel three-dimensional In-MOF with permanent porosity using electron-rich organic molecules 4'-[1,2,2-tris(3',5'-dicarboxy[1,1'-biphenyl]-4-yl)ethenyl]-[1,1'-biphenyl]-3,5-dicarboxylic acid (H8ETTB) for fluorescence detection by photoinduced electron transfer. The results indicated that In-ETTB can sensitively detect trace NACs in water. In-ETTB exhibited the best detection performance for 3-NP, achieving a Ksv value of 8.75 × 104 M-1 with a limit of detection of 0.27 μΜ in aqueous solution; this belongs to a relatively high level among the reported metal organic framework (MOF) materials. Subsequently, anti-interference experiments revealed that In-ETTB exhibits strong specificity fluorescence recognition of NACs, and it could still maintain its structural integrity and fluorescence emission intensity even after 7 cycles of testing. We confirmed that the fluorescence detection of NACs was due to a combined effect of competitive absorption and photoinduced electron transfer through experimental collaboration DFT calculations in detail. Meanwhile, the proton conductivity reached 2.45 × 10-2 S·cm-1 at 98% relative humidity and 90 °C, which is also a high level in MOFs. This work provides a universal method theoretical basis for designing NAC detectors with practical application prospects.

Dual-responsive two-photon probe for specific lipid droplets near-infrared fluorescence imaging in the brain of epileptic mice

Abnormal lipid metabolism in glial cells is a key pathological feature of epilepsy. The identification of lipid droplets (LDs) is essential for investigating lipid metabolism, disease progression, and potential therapeutic interventions. Two-photon imaging technology enables real-time visualization of the spatial distribution and temporal dynamics of LDs in epilepsy models. In this study, we developed a novel two-photon excited dual-responsive near-infrared fluorescent probe, CabA, based on viscosity and polarity, to monitor dynamic changes in LDs. The fluorescence of CabA at 670 nm exhibits a significant increase in response to low polarity and high viscosity due to the twisted intramolecular charge transfer and intramolecular charge transfer mechanisms. The LDs-targeting capability of CabA at the cellular level and the process of LDs generation between neurons and astrocytes during the pathological advancement of epilepsy have been validated. In situ synchronous imaging experiments in epileptic and normal mice using CabA revealed abnormal LDs accumulation in the brain during seizures. Two-photon fluorescence imaging further demonstrated LDs accumulation in the brains of epileptic mice at a penetration depth of 100 μm. This study offers a valuable tool for enhancing the understanding of LDs in physiological and pathological processes, potentially aiding in the early diagnosis of epilepsy.

Biosynthesis of gold cluster nanozyme within the structure of TetX2 monooxygenase protein

The synthesis of gold nanoclusters within protein structures, such as TetX2 monooxygenase, presents a promising approach for obtaining nanostructures with enzyme-like activity. This is attributed to the presence of various amino acid groups that serve as biological templates for the formation and reduction of gold. The low toxicity, biocompatibility, solubility in aqueous systems, and specific fluorescence spectrum of these nanostructures enhance their utility in the detection of various analytes. The research involved expressing and purifying the recombinant enzyme TetX2, synthesizing gold on the TetX2 substrate, and investigating the effect of nanoclusters on the activity and structure of the TetX2 enzyme. The synthesis of gold nanoclusters(AuNCs) was carried out within the structure of TetX2. Finally, the accuracy of the AuNCs synthesis was verified by examining the morphology, size, spectroscopy, and catalytic activity. Results showed changes in the tertiary structure of the TetX2 enzyme in the presence of HAuCl4, loss of enzyme activity after the formation of gold nanoclusters, and successful incorporation of gold into the structure of TetX2. TetX2@AuNCs emitted blue light at 450 nm, and their catalytic properties were demonstrated through color changes in a chromogenic substrate (3,3′,5,5′-Tetramethylbenzidine-H2O2), indicating their authenticity. TetX2 is proposed as a new bio-template forthe synthesis of gold nanoclusters, with potential applications in biosensor design (Graphical abstract).

Carbon dots-based dual-mode sensor for highly selective detection of nitrite in food substrates through diazo coupling reaction

As an antioxidant and preservative agent, nitrite (NO2−) plays an essential role in the food industry to maintain freshness or inhibit microbial growth. However, excessive addition of NO2− is detrimental to health, so accurate and portable detection of NO2− is critical for food quality control. Notably, the selectivity of most carbon dots (CDs)-based fluorescence sensors was not enough due to the nonspecific interaction mechanism of hydrogen bond, electrostatic interaction and inner filter effect etc. Herein, a novel fluorescence/UV–vis absorption (FL/UV–vis) dual-mode sensor was developed on basis of mC-CDs, which were prepared by simple solvothermal treatment of m-Phenylenediamine (m-PDA) and cyanidin cation (CC). The fluorescence of these mC-CDs could be selectively responded by NO2− through the specific diazo coupling reaction between NO2− and amino groups on the surface of mC-CDs, thus effectively improving the selectivity of NO2− detection. The CDs-based fluorescence sensor possessed a low detection limit of 0.091 μM and 0.143 μM for FL and UV–vis methods and the excellent linear range of 0.0–60.0 μM. Furthermore, the mC-CDs sensor was employed to detect NO2− in real samples with a recovery rate of 97.11 %–104.15 % for quantitative addition. Moreover, the smartphone-assisted fluorescence sensing platform developed could identify the subtle color changes that could not be distinguished by the naked eye, and had the advantages of fast detection speed and intelligence. More importantly, the portable solid phase sensor based on mC-CDs had been successfully applied to the specific fluorescence identification and concentration monitoring of NO2−. Accordingly, the designed sensor provided a new strategy for the highly selective and convenient sensing of NO2− in food substrates, and paved the way for the wide application of CDs-based nanomaterials in the detection of food safety.

A Fast, Efficient, and Tissue-Culture-Independent Genetic Transformation Method for Panax notoginseng and Lilium regale.

The Agrobacterium-based transgenic technique is commonly used for gene function validation and molecular breeding. However, it is not suitable for plants with a low regeneration capacity or a low transformation rate, such as Panax notoginseng (Burk) F.H. Chen and Lilium regale Wilson. In this study, a novel Agrobacterium transformation method based on injection in the meristems was developed using P. notoginseng and L. regale as experimental models. PCR analysis confirmed the successful integration of the reporter gene DsRed2 (Discosoma striata red fluorescence protein 2) into the genome of two experimental models. QRT-PCR and Western blot analysis demonstrated the transcriptional and translational expression of DsRed2. Additionally, laser confocal microscopy confirmed the significant accumulation of the red fluorescent protein in the leaves, stems, and roots of transformed P. notoginseng and L. regale. Most importantly, in the second year after injection, the specific bright orange fluorescence from DsRed2 expression was observed in the transgenic P. notoginseng and L. regale plants. This study establishes a fast, efficient, and tissue-culture-independent transgenic technique suitable for plants with a low regeneration capacity or a low transformation rate. This technique may improve the functional genomics of important medicinal and ornamental plants such as P. notoginseng and L. regale, as well as their molecular breeding.

A GSH-responsive NIR-BODIPY fluorophore with large Stokes-shift for tumor specific fluorescence imaging and surgical guidance

A GSH-responsive NIR-BODIPY fluorophore with large Stokes-shift for tumor specific fluorescence imaging and surgical guidance