Near-infrared Fluorescent Probe For Imaging Research Articles

Discovery of Natural Products Alleviating Renal Fibrosis with a Viscosity-Responsive Molecular Probe.

Renal fibrosis poses a significant threat to individuals suffering from chronic progressive kidney disease. Given the absence of effective medications for treating renal fibrosis, it becomes crucial to assess the extent of fibrosis in real time and explore the development of novel drugs with substantial therapeutic benefits. Due to the accumulation of renal tissue damage and the uncontrolled deposition of fibrotic matrix during the course of the disease, there is an increase in viscosity both intracellularly and extracellularly. Therefore, a viscosity-sensitive near-infrared fluorescence (NIRF) and photoacoustic (PA) imaging probe, BDP-KY, was developed to detect aberrant changes in viscosity during fibrosis. Furthermore, BDP-KY has been applied to screen the effective components of herbal medicine, rhubarb, resulting in the identification of potential antirenal fibrotic compounds such as emodin-8-glucoside and chrysophanol 8-O-glucoside. Ultrasound, PA, and NIRF imaging of a unilateral uretera obstruction mice model show that different concentrations of emodin-8-glucoside and chrysophanol 8-O-glucoside effectively reduce viscosity levels during the renal fibrosis process. The histological results showed a significant decrease in fibrosis factors α-smooth muscle actin and collagen deposition. Combining these findings with their pharmacokinetic characteristics, these compounds have the potential to fill the current market gap for effective antirenal fibrosis drugs. This study demonstrates the potential of BDP-KY in the evaluation of renal fibrosis, and the two identified active components from rhubarb hold great promise for the treatment of renal fibrosis.

Development of a highly specific NIR fluorescent probe for imaging of mitochondrial HOBr fluctuations

As an essential reactive oxygen species (ROS), hypobromous acid (HOBr) plays a vital role in the immune process. Nevertheless, excessive HOBr can cause a series of diseases including cancers. Therefore, the development of the in situ detection methods for intracellular HOBr in biosystems is urgent and important to further uncover the detailed physiological and pathological effects of HOBr. In this work, a simple water-soluble near-infrared (NIR) fluorescence dye was reasonably designed and synthesized, which was satisfactory chosen as a highly selective and sensitive fluorescent probe for the rapid detection of HOBr based on the electrophilic bromination reaction mechanism. This probe can perform the specific detection of HOBr, which facilitates the accurate imaging of HOBr in biosystems. Finally, this probe was successfully applied to trace mitochondrial HOBr fluctuations with high resolution in living cells and zebrafish.

Rational design of a near-infrared dual-emission fluorescent probe for ratiometric imaging of glutathione in cells.

Sensors for which the output signal is an intensity change for a single-emission peak are easily disturbed by many factors, such as the stability of the instrument, intensity of the excitation light, and biological background. However, for ratiometric fluorescence sensors, the output signal is a change in the intensity ratio of two or more emission peaks. The fluorescence intensity of these emission peaks is similarly affected by external factors; thus, these sensors have the ability to self-correct, which can greatly improve the accuracy and reliability of the detection results. To accurately image glutathione (GSH) in cells, gold nanoclusters (AuNCs) with intrinsic double emission at wavelengths of 606nm and 794nm were synthesized from chloroauric acid. With the emission peak at 606nm as the recognition signal and the emission peak at 794nm as the reference signal, a near-infrared dual-emission ratio fluorescence sensing platform was constructed to accurately detect changes in the GSH concentration in cells. In vitro and in vivo analyses showed that the ratiometric fluorescent probe specifically detects GSH and enables ultrasensitive imaging, providing a new platform for the accurate detection of active small molecules.

A transferrin receptor targeting dual-modal MR/NIR fluorescent imaging probe for glioblastoma diagnosis.

The prognosis of glioblastoma (GBM) remains challenging, primarily due to the lack of a precise, effective imaging technique for comprehensively characterization. Addressing GBM diagnostic challenges, our study introduces an innovative dual-modal imaging that merges near-infrared (NIR) fluorescent imaging with magnetic resonance imaging (MRI). This method employs superparamagnetic iron oxide nanoparticles coated with NIR fluorescent dyes, specifically Cyanine 7, and targeted peptides. This synthetic probe facilitates MRI functionality through superparamagnetic iron oxide nanoparticles, provides NIR imaging capability via Cyanine 7 and enhances tumor targeting trough peptide interactions, offering a comprehensive diagnostic tool for GBM. Notably, the probe traverses the blood-brain barrier, targeting GBM in vivo via peptides, producing clear and discernible images in both modalities. Cytotoxicity and histopathology assessments confirm the probe's favorable safety profile. These findings suggest that the dual-modal MR\NIR fluorescent imaging probe could revolutionize GBM prognosis and survival rates, which can also be extended to other tumors type.

Synthesis and Application of a Near-Infrared Light-Emitting Fluorescent Probe for Specific Imaging of Cancer Cells with High Sensitivity and Selectivity.

The preclinical diagnosis of tumors is of great significance to cancer treatment. Near-infrared fluorescence imaging technology is promising for the in-situ detection of tumors with high sensitivity. Here, a fluorescent probe was synthesized on the basis of Au nanoclusters with near-infrared light emission and applied to fluorescent cancer cell labeling. Near-infrared methionine-N-Hydroxy succinimide Au nanoclusters (Met-NHs-AuNCs) were prepared successfully by one-pot synthesis using Au nanoclusters, methionine, and N-Hydroxy succinimide as frameworks, reductants, and stabilizers, respectively. The specific fluorescence imaging of tumor cells or tissues by fluorescent probe was studied on the basis of SYBYL Surflex-DOCK simulation model of LAT1 active site of overexpressed receptor on cancer cell surface. The results showed that Met-NHs-AuNCs interacted with the surface of LAT1, and C_Score scored the conformation of the probe and LAT1 as five. Characterization and in vitro experiments were conducted to explore the Met-NHs-AuNCs targeted uptake of cancer cells. The prepared near-infrared fluorescent probe (Met-NHs-AuNCs) can specifically recognize the overexpression of L-type amino acid transporter 1 (LAT1) in cancer cells so that it can show red fluorescence in cancer cells. Meanwhile, normal cells (H9c2) have no fluorescence. The fluorescent probe demonstrates the power of targeting and imaging cancer cells.

Construction of a super large Stokes shift near-infrared fluorescent probe for detection and imaging of superoxide anion in living cells, zebrafish and mice

As one of the major reactive oxygen species (ROS), superoxide anion (O2•−) is engaged in maintaining redox homeostasis in the cell microenvironment. To identify the pathological roles in related disorders caused by abnormal expression of O2•−, it is of great significance to monitor and track the fluctuation of O2•− concentration in vivo. However, the low concentration of O2•− and the interference caused by tissue autofluorescence make the development of an ideal detection methodology full of challenges. Herein, a “Turn-On” chemical response near-infrared (NIR) fluorescence probe Dcm-Cu-OTf for O2•− detection in inflamed models, was constructed by conjugating the NIR fluorophore (dicyanisophorone derivative) with an O2•− sensing moiety (trifluoromethanesulfonate). Dcm-Cu-OTf exerted about 140-fold fluorescence enhancement after reacting 200 μM O2•− with an excellent limited of detection (LOD) as low as 149 nM. Additionally, Dcm-Cu-OTf exhibited a super large Stokes shift (260 nm) and high selectivity over other bio-analytes in stimulated conditions. Importantly, Dcm-Cu-OTf showed low toxicity and enabled imaging of the generation of O2•− in the Lipopolysaccharide (LPS)-stimulated HeLa cells, zebrafish, and LPS-induced inflamed mice. The present study provided a potential and reliable detection tool to inspect the physiological and pathological progress of O2•− in living biosystems.

A follicle-stimulating hormone receptor-targeted near-infrared fluorescent probe for tumor-selective imaging and photothermal therapy

Late detection, peritoneal dissemination, chemoresistance and weak response to targeted therapeutics lead to high mortality in ovarian cancer. More efficient and specific tumor imaging and therapeutic agents are needed to improve the resection rate of surgery and to eliminate residual disease. The expression patterns of follicle-stimulating hormone (FSH) receptor make it a suitable target for ovarian cancer. Here, we report a strategy to develop an organic near-infrared probe for FSH receptor-targeted tumor imaging and photothermal therapy. The FSH-Rh760 probe was conjugated from the Rh760 fluorophore with the FSH β subunit 33–53 peptide. FSH-Rh760 specifically distinguished peritoneal metastatic ovarian cancerous foci from surrounding normal tissues with a high tumor-to-background ratio. The fluorescence signals in tumors peaked at 2 h and were cleared at 120 h postinjection. FSH-Rh760 treatment rapidly increased the abdomen temperature of mice up to ∼43 °C upon exposure to a near-infrared laser and effectively suppressed peritoneal tumor growth with tumor specificity. No significant systemic toxicities were observed. This study demonstrates the targeting ability and biocompatibility of FSH receptor-targeted theranostics and highlights its potential for clinical application in imaging-guided precision tumor resection and photothermal therapy to eliminate cancer lesions intraoperatively and postoperatively.

Membrane cholesterol enrichment and folic acid functionalization lead to increased accumulation of erythrocyte-derived optical nano-constructs within the ovarian intraperitoneal tumor implants in mice

Cytoreductive surgery remains as the gold standard to treat ovarian cancer, but with limited efficacy since not all tumors can be intraoperatively visualized for resection. We have engineered erythrocyte-derived nano-constructs that encapsulate the near infrared (NIR) fluorophore, indocyanine green (ICG), as optical probes for NIR fluorescence imaging of ovarian tumors. Herein, we have enriched the membrane of these nano-constructs with cholesterol, and functionalized their surface with folic acid (FA) to target the folate receptor-α. Using a mouse model, we show that the average fraction of the injected dose per tumor mass for nano-constructs with both membrane cholesterol enrichment and FA functionalization was ~ sixfold higher than non-encapsulated ICG, ~ twofold higher than nano-constructs enriched with cholesterol alone, and 33 % higher than nano-constructs with only FA functionalization at 24-h post-injection. These results suggest that erythrocyte-derived nano-constructs containing both cholesterol and FA present a platform for improved fluorescence imaging of ovarian tumors.

Near-Infrared Fluorescent Switch-On Probe for Guanine-Quadruplex Imaging with Extremely Large Stokes Shift.

To visualize the guanine-quadruplex (G4) nucleic acids in cells or in biological tissues, near-infrared (NIR) fluorescent probes that can respond specifically to G4 nucleic acids are required. Herein, an NIR fluorescence switch-on probe for G4 imaging having higher selectivity and extremely large Stokes shift (ca. 220 nm) was successfully developed by the modification of our original tripodal quinone-cyanine fluorescent dye. The target binding-induced intramolecular stacking interaction of the probe might cause red shifting of the fluorescence emission. The NIR fluorescence switch-on probe developed here might contribute largely to revealing the behaviors of G4 nucleic acids not only in cells but also in biological tissues.

Construction of a mitochondria-targeted near-infrared fluorescence turn-on fluorescent probe for H2S detection and imaging in living cells and drug-induced mice inflammatory models

The mechanism of the interaction between the signaling molecule hydrogen sulfide (H2S) and mitochondria and its related diseases is difficult to elusive. Thus it is urgent to develop effective methods and tools to visualize H2S in mitochondria and in vivo. In this work, a robust mitochondrial-targeting NIR fluorescence “turn-on” fluorescent probe, NIR1, was reported, by adopting a Changsha-OH near-infrared (NIR) dye as the NIR fluorophore, a 2,4-dinitrophenyl (DNB) moiety as both the responsive site of the H2S and the fluorescence quenching group of the NIR fluorophore, and an oxygen onium ion site as the mitochondria-targeting group, for the detection and analysis of H2S in living Raw 264.7 cells and drug-induced inflammatory mice models. NIR1 exhibited a much smaller background fluorescence signal in lack of H2S, whereas strong enhanced NIR fluorescence “turn-on” was detected in the presence of H2S, these results showed a low detection limit (30.2 nM) for quantitative detection of H2S in aqueous solutions with concentrations ranging from 0 to 1 μM H2S. These characteristics were beneficial to direct detection and imaging analysis of H2S in complicated biosystems. Therefore, first, NIR1 was applied for the NIR detection of mitochondrial H2S in living inflammatory cells with satisfactory results. Finally, NIR1 was applied to detect H2S in drug-induced inflammatory mice models with agreeable results, demonstrating that NIR1 as a molecular tool has an excellent practical application in the study of the interaction between inflammatory and H2S.

A novel near-infrared fluorescent probe for specific imaging of telomerase reverse transcriptase in vivo

Identifying the expression levels of human telomerase reverse transcriptase (hTERT) is important for early cancer diagnosis and cancer-related drug screening. However, a small-molecule fluorescent probe has rarely been used for rapidly determining the hTERT level with high sensitivity has been scarce. Herein, we designed and synthesized a novel near-infrared fluorescent probe (NB-BIBRA) by conjugating an inhibitor analog (BIBRA) to the fluorophore Nile blue (NB) for specific imaging of hTERT in living cells and in vivo. In the absence of hTERT, NB-BIBRA mainly exists in aggregates, exhibiting self-quenching photoactivity. However, once NB-BIBRA interacts with hTERT, NB-BIBRA aggregates are disrupted and their fluorescence intensity is drastically enhanced. Notably, the probe exhibited a low detection limit, high selectivity and rapid response to hTERT, allowing rapid imaging of hTERT in living cells and solid tumor tissue in vivo. To the best of our knowledge, NB-BIBRA is the first near-infrared fluorescent probe for the detection and imaging of hTERT in living cells and in vivo, thus providing a powerful tool for early cancer diagnosis and cancer-related drug screening.

Rational design synthesis and evaluation of a novel near-infrared fluorescent probe for selective imaging of amyloid-β aggregates in Alzheimer's disease

Alzheimer's disease (AD) is a degenerative neurological disorder that remains incurable to date, seriously affecting the quality of life and health of those affected. One of the key neuropathological hallmarks of AD is the formation of amyloid-β (Aβ) plaques. Near-infrared (NIR) probes that possess a large Stokes shift show great potential for imaging of Aβ plaques in vivo and in vitro. Herein, we proposed a rational strategy for design and synthesis of a series of NIR fluorescent probes that incorporate a tricarbonitrile group as a strong electron-withdrawing group (EWG) to enable NIR emission and large Stokes shift for optimal imaging of Aβ plaques. The probe TCM-UM exhibited remarkable in vitro performance, including strong NIR emission (λem = 670 nm), large Stokes shift (120–245 nm), and its affinity for Aβ42 aggregates (Kd = 43.78 ± 4.09 nM) was superior to the commercially available probe Thioflavin T (ThT, Kd = 896.04 ± 33.43 nM). Further, TCM-UM was selected for imaging Aβ plaques in brain tissue slices and APP/PS1 transgenic (AD) mice, the results indicated that TCM-UM had an excellent ability to penetrate the blood-brain barrier (BBB) compared with ThT, and it could effectively distinguish wild-type (Wt) mice and APP/PS1 transgenic (AD) mice.

An extra-large Stokes shift near-infrared fluorescent probe for specific detection and imaging of cysteine

Cysteine (Cys) plays a crucial role in numerous physiological and pathological processes. Therefore, it is imperative to design a highly selective and sensitive near-infrared (NIR) fluorescent probe to monitor Cys. In this study, we have developed a novel NIR fluorescent probe XA based on Xanthene hybrid tetrahydro-acridine salt dye for specifically tracking of Cys, where a chlorine-substituted tetrahydro-acridine acts as a high Cys-reactive site and water-soluble group. Probe XA exhibits a remarkable "turn-on" NIR emission (830 nm) with an extra-large Stokes shift (305 nm) for monitoring Cys. It also has a high selectivity, rapid response time (6 min) and high sensitivity (LOD as 0.5 μM). We fully characterized and discussed the sensing mechanism of XA toward Cys using HPLC and MS spectrums, as well as quantum theory calculations. Furthermore, the excellent properties of NIR fluorescent detection allow this novel probe to successfully monitor fluctuations of exogenous and endogenous Cys concentration levels in living cells and in vivo.

(Invited) Bio-Applications of Carbon Nanotubes for NIR Imaging Probes and Guided Bone Regeneration Membranes

Single-walled carbon nanotubes (CNTs) have been expected for biological and medical applications because of their unique optical and chemical properties. One of the promising applications is imaging probes because CNTs show fluorescence in the near-infrared (NIR) region, which is highly transparent for biomaterials. We have reported the synthesis method of the epoxide-type oxygen-doped CNTs (Ep-CNTs) and their application as a near-infrared fluorescent probe [1-3]. Treated (6, 5) nanotubes show photoluminescence at ~1280 nm, which corresponds to the most transparent regions for biomaterials [1]. Immunoassay and fluorescence vascular angiography of mice were demonstrated by using the produced Ep-CNTs as infrared fluorescent labels [1,3] and imaging agents [1,2], respectively. From a practical point of view, the biodistributions of the Ep-CNTs imaging probe after administration to mice were investigated in detail [2]. In addition, the biological responses of mice following administration, which are relevant to safety, were also introduced [2].More recently, we found that CNTs exhibit high compatibility with bone tissue [4]. The guided bone regeneration (GBR) technique is commonly applied to reconstruct alveolar bone and treat peri-implant bone defects. It was found that CNT-based membrane for GBR exhibits high strength to provide a space for bone formation and provide cellular shielding to induce osteogenesis.In this meeting, we will report above biological and medical applications of CNTs in detail.1. Y. Iizumi, M. Yudasaka, J. Kim, H. Sakakita, T. Takeuchi, T. Okazaki, Oxygen-doped carbon nanotubes for near-infrared fluorescent labels and imaging probes, Sci. Rep., 8, 6272 (2018).2. T. Takeuchi, Y. Iizumi, M. Yudasaka, S. K. Kondoh, T. Okazaki, Characterization and biodistribution analysis of oxygen-doped single-walled carbon nanotubes used as in vivo fluorescence imaging probes, Bioconjugate Chem., 30, 1323−1330 (2019). (Cover Article)3. K. Kojima, Y. Iizumi, M. Zhang, T. Okazaki, Streptavidin-conjugated oxygen-doped single-walled carbon nanotubes as near-infrared labels for immunoassays, Langmuir, 38, 1509-1513 (2022).4. Y. Xu, E. Hirata, Y. Iizumi, N. Ushijima, K. Kubota, S. Kimura, Y. Maeda, T. Okazaki, A. Yokoyama, Single-walled Carbon Nanotube Membranes Accelerate Active Osteogenesis in Bone Defects: Potential of Guided Bone Regeneration Membranes, ACS Biomater. Sci. Eng., 8, 1667-1675 (2022).

A Near-Infrared Colorimetric Fluorescent Probe for Ferrous Ion Detection and Imaging.

Based on the N-redox mechanism, a turn-on near-infrared fluorescence probe (SWJT-15) with cyano isophorone as skeleton was designed and synthesized for the detection of ferrous ions (Fe2+). The probe has a lower detection limit (83 nM) and fast response (200s) to Fe2+ ions. And the probe has unique selectivity and good anti-interference performance against Fe2+ ions compared to other metal ions. Moreover, the probe has been successfully applied to imaging Fe2+ ions in HeLa cells.

A near-infrared fluorescence-on fluorescent probe for formaldehyde imaging in Arabidopsis thaliana

As a reactive carbonyl molecule, formaldehyde (FA) plays an important part in plant physiological and pathological activities. It is necessary to probe FA in plant for the study of its functions. In this paper, we report DISE, a dicyanoisophorone-based turn-on near-infrared fluorescent probe, which exhibits a highly sensitive response to FA. In addition, confocal imaging experiments showed that DISE could image endogenous and exogenous FA in Arabidopsis root tissue. It demonstrates that the probe has the potential to be an imaging tool to research the FA's biological roles in plant.

A near-infrared fluorescent probe for imaging of bisulfite in living animals and its application in food samples

Bisulfite (HSO3−) has been widely used as an antioxidant, enzyme inhibitor and antimicrobial agent in foodstuffs, pharmaceutical and beverages industries. It is also a signaling molecular in the cardiovascular and cerebrovascular systems. Nevertheless, a high level of HSO3− can cause allergic reactions and asthmatic attacks. Accordingly, the monitoring of HSO3− levels possesses momentous significance from the perspectives of biological technology and food security supervision. Herein, a near-infrared fluorescent probe LJ is rationally constructed for sensing HSO3−. The fluorescence quenching recognition mechanism was realized by the addition reaction of electron-deficient CC bond in probe LJ and HSO3−. Probe LJ revealed multifarious preponderances such as longer wavelength emission (710 nm), low cytotoxicity, larger Stokes shift (215 nm), better selectivity, higher sensitivity (72 nM) and short response time (50 s). Encouragingly, probe LJ can detect HSO3− in living zebrafish and mice in vivo by fluorescence imaging techniques. In the meantime, probe LJ was also successfully employed to semi-quantitatively detect HSO3− in real foodstuff samples and water samples by the “naked-eye” colorimetry without the help of any special instruments. More importantly, quantitative detection of HSO3− in practical food samples was achieved through a smartphone application software. Consequently, probe LJ is expected to provide an effective and convenient way for the detection and monitoring of HSO3− in organisms and for food safety detection, which has tremendous application potential.

Lysosome-targeted high resolution near-infrared fluorescent probe for low physiological pH imaging in vivo

Low physiological pH have an essential role in keeping the digestive function of stomach, avoiding infection and affecting the absorption effect of oral drugs, monitoring the minor fluctuations of low physiological pH is of great concern. An imidazopyridine-based ratiometric near-infrared (NIR) fluorescent probe SPO is rationally designed and synthesized for low physiological pH imaging. SPO exhibits high-resolution characteristics, including large Stokes shift (237 nm), remarkable emission shift (110 nm) and good fluorescence quantum yield (Φ = 0.68). It also possesses good reversibility, high selectivity and excellent photostability, and profits to monitoring of continuous pH changes. Moreover, ratiometric fluorescence imaging showed that the probe could conveniently and sensitively track the lysosomal pH fluctuation in living cells. The pKa value of SPO (pKa = 3.0) permits the accurate monitoring of the minor fluctuations of low physiological pH, and SPO was used for noninvasive monitoring gastric pH in living mice successfully.

A near-infrared fluorescent probe for fast and precise imaging of senescent cells and ovarian cancer cells via tracking β-galactosidase

Aging-related diseases are gradually becoming a major problem with the rapid development of aged population in human society. Although many fluorescent probes have been employed to diagnosis senescence via imaging senescence-associated β-galactosidase (SA-β-Gal), which is proved to be closely associated with senescent cells, the similar catalytic effectiveness of enzymatic reaction of ovarian cancer-associated β-Gal (OA-β-Gal) will interfere with imaging accuracy. Herein, a near-infrared (NIR) hemicyanine based fluorescent probe HCyXA-βGal was designed for light-up imaging of live cells containing β-Gal. With the organelle-targeting morpholinyl and positive charge moieties, HCyXA-βGal was successfully applicated to image the difference of enzymatic location in senescent cells and ovarian cancer cells. Furthermore, inspired by the fast response performance, fast and precise imaging of the two cell lines was realized via covering another dimension of fluorescence signal: time-dependent intensity.

Near-Infrared Fluorescent Probe for Imaging Upregulated Hydrogen Sulfide Levels in Rice under Salt and Drought Stress

Hydrogen sulfide (H2S) is a hazardous gas found in living organisms and is directly tied to our daily lives. Recent studies show that it plays a significant role in plant growth, development, and response to environmental stresses. However, few of the reported near-infrared (NIR) fluorescent probes have been applied to rice and deeply investigated the influence of the external environment on the biological molecules in its internal environment. Therefore, our team created BSZ-H2S, which has the advantage of an emission wavelength of up to 720 nm with fast response, successfully applying it to cell and zebrafish imaging. More importantly, the probe detected H2S in rice roots by in situ imaging in a facile manner and verified the existence of an upregulation process of H2S in response to salt and drought stress. This work provides a concept for the intervention of external stresses in rice culture.