Near-infrared Fluorescent Probe Research Articles

Discovery of Fatty Acid Translocase CD36-Targeting Near-Infrared Fluorescent Probe Enables Visualization and Imaging-Guided Surgery for Glioma.

Despite therapeutic advances in glioma, glioma-related mortality rates remain high due to its extremely poor prognosis and high recurrence. Near-infrared (NIR) fluorescence imaging technologies, using the clinically approved fluorescent probe 5-ALA, have gained prominence in facilitating visualization of glioma resection. However, the false-positive and false-negative results of 5-ALA decrease its sensitivity and specificity in detecting glioma, thereby hampering its use in glioma surgical navigation. Herein, a novel molecular probe MPA-Pip-abt-510 labeled with a NIR fluorescent dye MPA was developed, and its ability to target the CD36 protein, which is upregulated in glioma, was assessed. Fluorescent-labeled probes, conjugated to the CD36-targeting ligand abt-510, demonstrated high specificity and selectivity for CD36-positive tumor cells in vitro and tumor tissue in vivo. Biodistribution analysis of MPA-Pip-abt-510 revealed high tumor-specific accumulation in tumors, accompanied by minimal nonspecific uptake in background tissues, yielding a signal-to-noise ratio (SNR) of 6.6 ± 0.4 in a U87 subcutaneous glioma model 10 h postinjection. Meanwhile, quantitative analysis validated the high uptake of MPA-Pip-abt-510 in the U87 orthotopic tumor model, with a tumor-to-brain SNR of 5.4 ± 0.5, enabling the accurate identification of tumor tissue for surgical navigation. Moreover, pathological analysis of tumor and healthy brain tissues unveiled well-defined tumor boundaries, highlighting the capacity of the MPA-Pip-abt-510 probe to precisely visualize the CD36 protein at the molecular level. Given its rapid tumor-targeting abilities, durable retention, and accurate outlining of tumor boundaries, MPA-Pip-abt-510 emerges as a promising CD36-targeted fluorescence contrast agent and expands the toolbox of glioma fluorescent probes for surgical navigation.

A NIR fluorescent probe based on carbamoyl oxime with high specificity for detecting ferrous ions in food and in vivo.

Ferrous ions (Fe2+), the primary form of iron in cells, play a crucial role in various biological processes. The presence and absorption of Fe2+ in food has an important impact on human health. Proper dietary intake and iron supplementation are conducive to prevent and treat iron-related diseases. Therefore, it is of great value to develop tools that can specifically and sensitively detect Fe2+ in foods and organisms. Near-infrared (NIR) fluorescent probes have attracted much attention due to their advantages including deep tissue penetration and lower background fluorescence. Herein, a NIR fluorescent probe DICO-Fe(II) with a new recognition mechanism was constructed. DICO-Fe(II) achieves the highly specific recognition of Fe2+ through its carbamoyl oxime recognition site and exhibits high sensitivity with a limit of detection of 47nM. DICO-Fe(II) can quantitatively detect Fe2+ with the naked eye through RGB values. It was also successfully applied to detect Fe2+ in food samples, cells, zebrafish, and mice tissues, confirming its potential as a modern analytical tool for the detection of Fe2+ in food and biological organisms.

Building an eco-friendly, biocompatible, and ratiometric NIR fluorescent sensor for the rapid detection of trace Pd2+ in real samples and living cells.

The increasing industrial use of palladium has led to its environmental accumulation, raising concerns about its toxicity to aquatic life and human health. Therefore, fluorescent probes capable of detecting Pd2+ are highly beneficial. With this objective, a new near-infrared (NIR) fluorescent probe based on a cyanine dye, 2 ((E)-2-((E)-2-((dimethylcarbamothioyl)oxy)-3-(2-((Z)-1,3,3-trimethylindolin-2ylidene)ethylidene)cyclohex -1-en-1-yl)vinyl)-1,3,3-trimethyl-3H-indol-1-ium iodide (CNS), was synthesized for selective and rapid detection of Pd2+. The detection reaction followed the elimination of thiocarbamate moiety, leading to the highly fluorescent product. CNS demonstrated remarkable sensitivity (detection limit: 0.105 μM), high selectivity, short response time (1.0 min), long lifetime (0.88 ns), and easily detectable color changes upon Pd2+ exposure. A CNS-loaded TLC strip integrated with a smartphone detection system was able to detect Pd2+ in solutions, soil, and drug samples. In addition, CNS enabled concentration-dependent detection of Pd2+ in onion roots and epidermis. Because of low cytotoxicity, good membrane permeability, NIR fluorescence, and high contrast, CNS has been successfully applied to Pd2+ bioimaging in living cells, targeting mitochondria. Compared to existing probes, CNS offers superior sensitivity, selectivity, and adaptability for sensing applications.

Fabrication of a carboxylesterases-activated near-infrared fluorescence probe for assisting hepatocellular carcinoma surgery in mice and clinical blood serum testing

Fabrication of a carboxylesterases-activated near-infrared fluorescence probe for assisting hepatocellular carcinoma surgery in mice and clinical blood serum testing

A near-infrared fluorescent probe for detecting hydrogen sulfide and its applications in monitoring food freshness and bioimaging

A near-infrared fluorescent probe for detecting hydrogen sulfide and its applications in monitoring food freshness and bioimaging

Ultra-large Stokes-shifted NIR fluorescent probes for the diagnosis and treatment of rheumatoid arthritis via metal-free tracking of carbon monoxide

Ultra-large Stokes-shifted NIR fluorescent probes for the diagnosis and treatment of rheumatoid arthritis via metal-free tracking of carbon monoxide

A novel prostate cancer-specific fluorescent probe based on extracellular vesicles targeting STEAP1 applied in fluorescence guided surgery.

Radical prostatectomy with pelvic lymph node dissection is the best treatment for intermediate- to high-risk localized prostate cancer (PCa). However, conventional white light surgery has difficulties in identifying tumor boundary and micrometastases intraoperatively. Fluorescence guided surgery (FGS) can solve the above difficulties, but lacks tumor-specific near-infrared fluorescent (NIRF) probes in PCa. STEAP1 was an ideal target in PCa treatment and imaging. Here, we constructed a PCa specific fluorescent probe based on extracellular vesicles targeting STEAP1 (AS-EVs) loaded with NIRF dye S0456 and evaluated its preclinical profiles. In vitro and in vivo studies both showed S0456@AS-EVs was safe and showed strong targeting ability to PCa in various mice xenograft models. S0456@AS-EVs could clear rapidly from blood (half-time of 4.29 h) and retain in the STEAP1 positive tumor tissues for more than 72 h with the highest tumor background ratio (TBR) of 3:1, which was superior to ICG, free S0456, ICG@Ctrl-EVs and S0456@Ctrl-EVs (p < 0.01). Finally, S0456@AS-EVs was applied in FGS on intramuscular model, and the tumors were resected under white light and fluorescence respectively. Compared with white light surgery, mice undergoing FGS had lower positive margin rate and better postoperative survival (p = 0.0342).

A Triple-Responsive and Dual-NIR Emissive Fluorescence Probe for Precise Cancer Imaging and Therapy by Activating Pyroptosis Pathway.

Revealing changes in the tumor microenvironment is crucial for understanding cancer and developing sensitive methods for precise cancer imaging and diagnosis. Intracellular hydrogen peroxide (H2O2) and microenvironmental factors (e.g., viscosity and polarity) are closely linked to various physiological and pathological processes, making them potential biomarkers for cancer. However, a triple-response theranostic probe for precise tumor imaging and therapy has not yet been achieved due to the lack of effective tools. Herein, we present a mitochondria-targeting near-infrared (NIR) fluorescent probe, VPH-5DF, capable of simultaneously monitoring H2O2, viscosity, and polarity through dual NIR channels. The probe specifically detects H2O2 via NIR emission (λem = 650 nm) and shows high sensitivity to microenvironmental viscosity/polarity in the deep NIR channel (λem ≈ 750 nm). Furthermore, the probe not only monitors mitochondrial polarity, viscosity, and fluctuations in endogenous/exogenous H2O2 levels but also distinguishes cancer cells from normal cells through multiple parameters. Additionally, VPH-5DF can be employed to monitor alterations in H2O2 levels, as well as changes in viscosity and polarity, during drug-induced pyroptosis in living cells. After treatment with VPH-5DF, chemotherapy-induced oxidative damage to the mitochondria in tumor cells activated the pyroptosis pathway, leading to a robust antitumor response, as evidenced in xenograft tumor models. Thus, this triple-response theranostic prodrug offers a new platform for precise in vivo cancer diagnosis and anticancer chemotherapy.

Application of a CYP1B1-Targeted NIR Probe for Breast Cancer Diagnosis, Surgical Navigation, and CYP1B1-Associated Chemotherapy Resistance Monitoring.

Early detection and precise treatment for breast cancer are crucial, given its high global incidence rate. Hence, the development of novel imaging targets is essential for diagnosing and monitoring resistance to chemotherapy, which is pivotal for achieving precise and personalized treatment for breast cancer patients. In our previous work, we successfully developed a near-infrared (NIR) probe 1 for CYP1B1-targeted imaging. In this study, we aimed to investigate the utility of the probe as a NIR fluorescence and photoacoustic dual-mode imaging probe for the detection and surveillance of breast cancer. Western blotting of cancer cell lines has confirmed that CYP1B1 is widely expressed in breast cancer and gynecological cancer. In vitro NIR fluorescence imaging capability of the probe for tracking CYP1B1-positive tumor cells was validated by using confocal microscopy. Further studies, including in vivo fluorescence and photoacoustic dual-model imaging and ex vivo biological distribution analysis on a triple-negative breast cancer xenograft mouse model, demonstrated that the probe selectively accumulated in tumor tissue within as early as 0.5 h postinjection. The results of the surgical resection experiment revealed that the tumor could be entirely removed under the guidance of NIR imaging, thereby indicating the probe's efficacy in surgical navigation. CYP1B1 expression was found to be upregulated in adriamycin (ADR)-resistant breast cancer cells, MCF-7/ADR. Consequently, the sensitivity of CYP1B1 overexpressed cells, MCF-7/1B1, to ADR was significantly reduced, with an IC50 value of 0.586 ± 0.0934 μM, compared to the parental MCF-7 cells with an IC50 value of 0.183 ± 0.0444 μM. In vivo and ex vivo imaging assays conducted on MCF-7/ADR tumor-bearing mice demonstrated that the probe was specifically enriched in tumor sites, suggesting its potential for monitoring chemotherapy resistance in breast cancer. This study expands the scope of application for NIR probe 1, establishing its utility in breast cancer diagnosis through fluorescence-photoacoustic dual-model imaging, monitoring of chemotherapy resistance, and guidance for surgical resection. This strategy paves the way for novel approaches to precise and personalized treatment for breast cancer patients.

Monitoring Dynamic Changes of Cellular Membrane GSH During Stroke via an ESIPT-Based Near-Infrared Fluorescent Probe

Stroke, primarily ischemic (85%), results from inadequate blood supply and is worsened by ferroptosis, characterized by free radical generation and lipid peroxidation. Monitoring ferroptosis is essential for understanding its mechanisms and developing treatments. Glutathione (GSH) is a key ferroptosis biomarker, but current probes are limited by short excitation/emission wavelengths, small Stokes shifts, and inability to monitor dynamic GSH changes at the cellular membrane, where ferroptosis plays a crucial role. To address these issues, we developed the PM-Red-GSH, a novel near-infrared (NIR) probe based on the Excited-state intramolecular proton transfer (ESIPT) mechanism. It shows strong NIR emission (715 nm), large Stokes shift (290 nm), and enhanced membrane binding (PCC = 0.95) due to its alkyl group. PM-Red-GSH enables dynamic GSH monitoring in an MCAO mouse model. These findings offer new insights into ferroptosis and stroke treatment.

Super-Resolution Mitochondrial Fluorescent Probe for Accurate Monitoring of Drug-Induced Liver Injury.

Drug-induced liver injury (DILI) has emerged as an urgent clinical challenge. It is characterized by mitochondrial dysfunction in liver cells, which leads to abnormal changes in H2O2 levels within the mitochondria. Super-resolution imaging allows for the observation of the fine structure of mitochondria at the nanometer scale, potentially enabling the detection of mitochondrial H2O2 levels during DILI at the subcellular organelle level. Here, we report the design and synthesis of a novel H2O2-activated probe for the detection of mitochondrial H2O2 levels. SML is a near-infrared (NIR) fluorescent probe with a large Stokes shift (260 nm) and a sensing mechanism based on intramolecular charge transfer (ICT) switching. Super-resolution imaging of mitochondrial H2O2 was conducted using structured illumination microscopy (SIM). The improved accuracy in observing periods of mitochondrial dysfunction allows the SML probe to be effectively utilized for the rapid monitoring nanoscale upregulation of H2O2 during DILI and hepatic fibrosis, thus providing SML with the capability to screen for effective therapeutic candidates.

Engineering a Novel NIR RNA-Specific Probe for Tracking Stress Granule Dynamics in Living Cells.

Real-time monitoring of the dynamics of cytosolic RNA-protein condensates, termed stress granules (SGs), is vital for understanding their biological roles in stress response and related disease treatment but is challenging due to the lack of simple and accurate methods. Compared with protein visualization that requires complex transfection procedures, direct RNA labeling offers an ideal alternative for tracking SG dynamics in living cells. Here, we propose a novel molecular design strategy to construct a near-infrared RNA-specific fluorescent probe (HQBT) for tracking SGs in living cells. The positively charged probe HQBT was designed to target the negative groove of RNA, and its binding affinity to RNA was significantly improved by adjusting the position of the nitrogen atom in the molecule. Furthermore, an additional hydroxyl group was introduced to achieve near-infrared emission and enhance the RNA-binding capability. HQBT can rapidly stain RNA within 5 s in living cells and showed performance superior to the commercial SYTO RNA-Select dye in terms of photostability and selectivity. Importantly, the reversible assembly and disassembly dynamics of SGs are successfully visualized in living cells using this simple and direct RNA-selective imaging probe.

Near-infrared fluorescent probes based on naphthyridine derivatives for mitochondrial nucleic acid imaging.

Most current nucleic acid-responsive fluorescent probes are enhanced ones with short emission wavelengths. Therefore, the development of novel near-infrared, turn-on response nucleic acid fluorescent probes is of great significance. Herein, three cationic fluorescent dyes 1a-1c were synthesized by reacting naphthalidine salt with suitable aldehydes. These probes exhibited excellent photostability, maintaining over 95% of their absorption rate after 5 h of irradiation. Notably, probes 1a-1c exhibited an OFF-ON fluorescence response to DNA and RNA. The maximum emission wavelength could reach the near-infrared region (661-762 nm), with large Stokes shifts (153-222 nm) upon binding to DNA/RNA. The fluorescence intensity was enhanced 143 fold and 127 fold for 1b upon interaction with DNA and RNA, respectively. Co-staining and nucleic acid digestion assays showed that probes 1a-1c could target the mitochondria of fixed cells with low cytotoxicity. These findings may be useful for the early screening of genetic mutations related to mitochondrial diseases.

Development of Off-On Near-Infrared Fluorescent Probes for Sensitive In Vivo Imaging of Amyloid-β Species with Enhanced Pharmacokinetics.

The fluorescent imaging of pathologically accumulated β-amyloid (Aβ) proteins is of significant importance to the diagnosis of Alzheimer's disease (AD). In the paper, we prepare two new NIR probes, NIR-1 and NIR-2, through hydrophilic modification of introducing water-soluble bioactive groups such as polyethylene glycol (PEG) and morpholine to tune in vivo pharmacokinetics for specific detection of soluble and insoluble Aβ species. The in vitro assessments confirm that both NIR-1 and NIR-2 display strong near-infrared (NIR) fluorescence (FL) enhancement upon interaction with Aβ42 monomers, oligomers or aggregates (λem>670 nm) and show highly sensitive, rapid and selective response towards Aβ42 species. After i. v. injection, each probe showed fast blood-brain barrier (BBB) penetration and immediately produced intense FL signals in the brain of APP/PS1 AD model mice at 10 min. Moreover, compared with NIR-2, NIR-1 bearing a hydrophilic PEG chain displayed not only more rapid clearance but also lower background signal to efficiently distinguish APP/PS1 mice and wild-type mice with higher signal-to-background ratio, which was further validated by ex vivo histological staining of brain tissues. Therefore, due to its excellent pharmacokinetics, NIR-1 shows great promise as an effective NIR probe for specific detection of Aβ species.

Near-Infrared Fluorescent Probe for Simultaneously Imaging Ferrous Ions and Viscosity in a Mouse Model of Hepatocellular Carcinoma.

Abnormal ferrous ion (Fe2+) levels lead to an increase in reactive oxygen species (ROS) in cells, disrupting intracellular viscosity and the occurrence of hepatocellular carcinoma (HCC). Simultaneously visualizing Fe2+ and intracellular viscosity is essential for understanding the detailed pathophysiological processes of HCC. Herein, we report the first dual-responsive probe, QM-FV, capable of simultaneously monitoring Fe2+ and viscosity. QM-FV shows highly selective turn-on near-infrared fluorescence (∼30-fold enhancement at 740 nm) for Fe2+ with high sensitivity (LOD = 25 nM) and a significant Stokes shift (290 nm). Moreover, QM-FV shows a distinct orange-red fluorescence enhancement at 587 nm as the viscosity increases. Due to its lower cytotoxicity and high sensitivity, QM-FV can distinguish cancer cells from normal cells by detecting Fe2+ and viscosity in dual channels. More importantly, using QM-FV, we found that the levels of Fe2+ and viscosity elevated in the precancerous stage of HCC and gradually increased as the disease progressed. Overall, this work provides a new potential tool for investigating viscosity and Fe2+-related pathological processes underlying HCC.

Monomeric or Homodimer Conjugates of Fibroblast Activation Protein Inhibitor and Cyanine 7 Bearing a Meso-Chloride as Near-Infrared Fluorescence Probes: Design, Synthesis, and Comparative In Vivo Imaging of Distinct Breast Cancer Subtypes.

Intraoperative fluorescence navigation can illuminate the tumor, directing surgeons to accurately achieve negative margins, which not only reduces recurrence but also minimizes the incidence of complications. Herein, we developed two near-infrared fluorescent probes FAPI-Cy7-Cl (Emmax = 820 nm) and (FAPI)2-Cy7-Cl (Emmax = 823 nm) with prolonged tumor retention (>72 h) and high target-to-background ratios (up to 4.5) based on the conjugation of pan-cancer targeted fibroblast activation protein inhibitor (FAPI) and the "tumor-seeking" Cyanine 7 bearing a meso-chloride and a cyclohexenyl skeleton (Cy7-Cl). Specifically, FAPI-Cy7-Cl exhibited superior imaging performance in both estrogen receptor α positive breast cancer (MCF-7) and triple-negative breast cancer (TNBC) (MDA-MB-231) subtypes in mouse models. Notably, in the MDA-MB-231 tumor-bearing model, the tumor-to-liver ratio (T/L) of FAPI-Cy7-Cl increased rapidly after 2 h postinjection, reaching nearly 4.5 at 48 h, making it an optimal imaging probe for guiding TNBC surgery resection.

Nanoparticle-Enhanced Near-Infrared Fluorescence Probes: A Breakthrough in Cancer Imaging Techniques

Nanoparticle-Enhanced Near-Infrared Fluorescence Probes: A Breakthrough in Cancer Imaging Techniques

Near-Infrared Probes Designed with Hemicyanine Fluorophores Featuring Rhodamine and 1,8-Naphthalic Derivatives for Viscosity and HSA Detection in Live Cells.

This paper presents the development of near-infrared (NIR) fluorescent probes, A and B, engineered from hemicyanine dyes with 1,8-naphthalic and rhodamine derivatives for optimized photophysical properties and precise mitochondrial targeting. Probes A and B exhibit absorption peaks at 737 nm and low fluorescence in phosphate-buffered saline (PBS) buffer. Notably, their fluorescence intensities, peaking at 684 (A) and 702 nm (B), increase significantly with viscosity, as demonstrated through glycerol-to-PBS ratio experiments. This increase is attributed to restricted rotational freedom in the fluorophore and its linkages to rhodamine or 1,8-naphthalic groups. Theoretical modeling suggests nonplanar configurations for both probes, with primary absorptions in the rhodamine and hemicyanine cores (A: 543; B: 536 nm), and additional transitions to 1,8-naphthalic (A: 478 nm) and rhodamine (B: 626 nm) groups. Probe A is also responsive to human serum albumin (HSA), a key biomarker, with fluorescence increasing in HeLa cells as HSA concentrations rise. In contrast, probe B shows no response to HSA, likely due to steric hindrance from its bulky rhodamine group, illustrating a selectivity difference between the probes. Probe B, however, excels in mitochondrial imaging, confirmed through cellular and in vivo studies. In HeLa cells, it tracked viscosity changes following treatment with monensin, nystatin, and lipopolysaccharide (LPS), with fluorescence increasing in a dose-dependent manner. In fruit flies, probe B effectively detected monensin-induced viscosity changes, demonstrating its stability and in vivo applicability. These findings highlight the versatility and sensitivity of probes A and B as tools in biological research, with potential applications in monitoring mitochondrial health, detecting biomarkers like HSA, and investigating mitochondrial dynamics in disease.

Selenocysteine-Activatable Near-Infrared Fluorescent Probe for Screening of Anti-inflammatory Components in Herbs.

Inflammation, a central process in numerous diseases, plays a crucial role in hepatic disorders, arthritis, cardiac conditions, and neurodegenerative ailments. Given the lack of effective anti-inflammatory drugs, it is imperative to assess inflammation severity and explore novel therapeutics. Selenocysteine (Sec), a key mediator of selenium's biological function, is closely involved in anti-inflammatory responses. We have synthesized a novel near-infrared fluorescent probe, Sec-BDP, which can image Sec dynamics in vivo with high selectivity and sensitivity. Sec-BDP detects Sec at concentrations as low as 0.085 μM. Utilizing this probe, we visualized Sec levels in cell, zebrafish, and mouse inflammation models, enabling a clear assessment of inflammation severity. To screen for drug candidates, Sec-BDP was integrated with ultrahigh performance liquid chromatography quadrupole time-of-flight mass spectrometry to identify potent anti-inflammatory compounds in Astragalus membranaceus, such as 5-O-methylvisammioside. Imaging of Sec with Sec-BDP provides insights into Sec-related diseases and aids in discovering new treatments. This probe advances selenium biology and promises more targeted therapeutic strategies.

Zero-Crosstalk Tumor-Targeting Ratiometric Near-Infrared γ-Glutamyltranspeptidase Probe for Fluorescent-Guided Surgical Resection of Orthotopic Hepatic Tumor.

The challenge of "false positive" signals significantly complicates tumor localization and surgical resection, which are pivotal for successful tumor surgeries. Therefore, the development of a method for preoperative tumor localization and intraoperative margin determination holds considerable promise for improving surgical outcomes. In this study, a zero-crosstalk ratiometric tumor-targeting near-infrared (NIR) fluorescent probe was developed for precise cancer diagnosis and intraoperative navigation via NIR fluorescence imaging. This probe integrates a tumor-targeting moiety that selectively homes in on hepatocellular carcinoma cells and exhibits a highly sensitive ratiometric response to γ-glutamyltranspeptidase (GGT), characterized by a substantial emission shift from 830 to 650 nm. This unique NIR ratiometric emission property significantly enhances its effectiveness in early diagnosis and imaging-guided surgery resection. Furthermore, this zero-crosstalk probe successfully monitors GGT activity in blood, cells, and in vivo, endowing its potential for early cancer diagnosis in the clinic. Due to its efficient targeting and sensitive in situ response to GGT in both subcutaneous tumors and orthotopic hepatic tumors, the probe exhibits accurate detection capability for hepatic tumors. Additionally, by leveraging zero-crosstalk ratiometric NIR fluorescence imaging, this tumor-targeting probe can serve as a sprayable tool for delineating tumor margins with precision, thereby furnishing real-time intraoperative imaging guidance during tumor resection surgery.