Dual-modality Probe Research Articles

Ratiometric H2S probe that can be recognized by the naked eye and its application in cell imaging

A ratiometric dual-mode probe NI-SH based on 1,8-Naphthalimide was prepared for H2S detection. When treated with H2S, the fluorescence of NI-SH changes from blue (456 nm) to green (540 nm), and displays significant color variation (colorless to yellow) that can visible to the naked eye. Further investigation shows that the NI-SH has high sensitivity, selectivity, and low detection limit at about 0.2 μM, and with large Stokes shift (84 nm). The intermolecular charge transfer (ICT) response mechanism of NI-SH was further studied by analyzing the distributions of the molecular orbital. Besides, NI-SH exhibits a ratiometric fluorescence response in living Hela cells.

Pre- and Intraoperative Visualization of GRPR-Expressing Solid Tumors: Preclinical Profiling of Novel Dual-Modality Probes for Nuclear and Fluorescence Imaging

Image-guided surgery using a gastrin-releasing peptide receptor (GRPR)-targeting dual-modality probe could improve the accuracy of the resection of various solid tumors. The aim of this study was to further characterize our four previously developed GRPR-targeting dual-modality probes that vary in linker structures and were labeled with indium-111 and sulfo-cyanine 5. Cell uptake studies with GRPR-positive PC-3 cells and GRPR-negative NCI-H69 cells confirmed receptor specificity. Imaging and biodistribution studies at 4 and 24 h with 20 MBq/1 nmol [111In]In-12-15 were performed in nude mice bearing a PC-3 and NCI-H69 xenograft, and showed that the probe with only a pADA linker in the backbone had the highest tumor-to-organ ratios (T/O) at 24 h after injection (T/O > 5 for, e.g., prostate, muscle and blood). For this probe, a dose optimization study with three doses (0.75, 1.25 and 1.75 nmol; 20 MBq) revealed that the maximum image contrast was achieved with the lowest dose. Subsequently, the probe was successfully used for tumor excision in a simulated image-guided surgery setting. Moreover, it demonstrated binding to tissue sections of human prostate, breast and gastro-intestinal stromal tumors. In summary, our findings demonstrate that the developed dual-modality probe has the potential to aid in the complete surgical removal of GRPR-positive tumors.

Contractile Hairpin DNA-Mediated Dual-Mode Strategy for Simultaneous Quantification of Lactoferrin and Iron Ion by Surface-Enhanced Raman Scattering and Fluorescence Analysis.

DNA-mediated self-assembly technology with good sensitivity and affinity ability has been rapidly developed in the field of probe sensing. The efficient and accurate quantification of lactoferrin (Lac) and iron ions (Fe3+) in human serum and milk samples by the probe sensing method can provide useful clues for human health and early diagnosis of anemia. In this paper, contractile hairpin DNA-mediated dual-mode probes of Fe3O4/Ag-ZIF8/graphitic quantum dot (Fe3O4/Ag-ZIF8/GQD) NPs were prepared to realize the simultaneous quantification of Lac by surface-enhanced Raman scattering (SERS) and Fe3+ by fluorescence (FL). In the presence of targets, these dual-mode probes would be triggered by the recognition of aptamer and release GQDs to produce FL response. Meanwhile, the complementary DNA began to shrink and form a new hairpin structure on the surface of Fe3O4/Ag, which produced hot spots and generated a good SERS response. Thus, the proposed dual-mode analytical strategy possessed excellent selectivity, sensitivity, and accuracy due to the dual-mode switchable signals from "off" to "on" in SERS mode and from "on" to "off" in FL mode. Under the optimized conditions, a good linear range was obtained in the range of 0.5-100.0 μg/L for Lac and 0.01-5.0 μmol/L for Fe3+ and with detection limits of 0.14 μg/L and 3.8 nmol/L, respectively. Finally, the contractile hairpin DNA-mediated SERS-FL dual-mode probes were successfully applied in the simultaneous quantification of iron ion and Lac in human serum and milk samples.

Dual Chemiexcitation by a Unique Dioxetane Scaffold Gated by an OR Logic Set of Triggers.

Chemiexcitation of phenoxy-1,2-dioxetane chemiluminescent luminophores is initiated by electron transfer from a meta-positioned phenolate ion to the peroxide-dioxetane bond. Here we report the development of a unique 1,2-dioxetane chemiluminescent scaffold with chemiexcitation gated by an OR logic dual-set of triggering events. This scaffold is composed of meta-dihydroxyphenyl-1,2-dioxetane-adamantyl molecules, equipped with acrylic acid and chlorine substituents, that chemiexcitation under physiological conditions. A dual-mode chemiluminescent probe, armed with two different triggering substrates designed for activation by the enzymes β-galactosidase and alkaline phosphatase, was synthesized. The probe emitted intense light signals in the response to each enzyme, demonstrating its ability to serve as a single-component chemiluminescent sensor for dual-analyte detection. We also demonstrated the ability of the probe to detect β-galactosidase and phosphatase activities in bacteria. This is the first 1,2-dioxetane scaffold capable of responding to two different chemiexcitation events from two different positions on the same dioxetane molecule. We anticipate that the OR-gated mode of chemiexcitation, described herein, will find utility in the preparation of chemiluminescent probes with a dual-analyte detection/imaging mode.

Dual-mode supramolecular fluorescent probe for rapid and on-site detection of chlorpyrifos in the environment

Chlorpyrifos (CPF) as a classic organophosphorus pesticide has been widely used in agricultural applications to control insects and worms. CPF in the environment can cause deaths of diverse kinds of aquatic organism and bring a high risk to human health. Therefore, the development of effective analytical method for CPF is of great importance. In this work, a novel dual-mode albumin (ALB)-based supramolecular probe FD@ALB was designed and prepared for rapid detection of CPF in the environment. The limit of detection is 0.57 μM (∼ 0.2 ppm) with a wider detection range up to 200 μM, which is satisfactory for application. The sensing mechanism can be ascribed to CPF-induced phosphorylation of ALB, thus leading to a change in the binding microenvironment of FD dye. Moreover, the paper-based test strips were used in conjunction with the FD@ALB, realizing the portable detection of CPF. This method was demonstrated to be suitable for on-site detection of CPF in various kinds of environmental samples, including water, soil, and food samples, with the aid of a smartphone. To the best of our knowledge, this is the first analytical method achieving a combination of the rapid and ratiometric detection of CPF in the environment.

A robust ratiometric photoacoustic and fluorescence dual-modal molecular probe for capturing endogenous HNO generation in tumor mice model

HNO is reported in association with a wide variety of physiological and pathological states. However, photoacoustic (PA)/fluorescence (FL) dual-modal probes with complementary advantages for detection of HNO in living systems, especially in tumors, are still lacking. Herein, the first near-infrared (NIR) ratiometric PA/FL dual-modal probe (DOP-HNO), composed of a dual ratiometric molecular skeleton caged with 2-(diphenylphosphino)-benzoate group, was designed and synthesized for capturing endogenous HNO generation in vivo. DOP-HNO was able to specifically and sensitively respond to HNO with 4-fold ratiometric fluorescence enhancement (F783/F720) and 2.6-fold ratiometric PA enhancement (PA740/PA670). Moreover, DOP-HNO successfully visualized HNO fluctuations in 4T1 cells and living mice, and the crosstalk between NO and H2S in the tumors of living mice was clearly observed through NIR dual-ratiometric PA/FL imaging, indicating the accurate detection of HNO in vivo. More importantly, using DOP-HNO, for the first time, we provided the visualization evidence of endogenous HNO generation in cancer model and further investigated its possible generation mechanisms by H2S/NO interaction. Thus, we envision that the dual-modal probe DOP-HNO will be an effective tool to study the complex relationship between HNO and cancer as well as the pathology of other HNO-related diseases.

Neuropilin 1-targeted near-infrared fluorescence probes for tumor diagnosis

Two neuropilin 1 (NRP1)-targeted near-infrared fluorescence probes for tumor imaging were synthesized via click reaction. These two probes achieve excellent solubility and less aggregation. Importantly, they were able to rapidly target NRP1-overexpressing tumors and had long retention within tumors. Additionally, QS-1 with appropriate hydrophilicity displays higher tumor to muscle (T/M) ratio. And QS-1 can be easily modified with other functional group, and serve as a platform for constructing dual-modal or dual-targeting probes.

Intracerebral Fluorescence-Photoacoustic Dual-Mode Imaging for Precise Diagnosis and Drug Intervention Tracing in Depression.

Unravelling the pathophysiology of depression is a unique challenge. Depression is closely associated with reduced norepinephrine (NE) levels; therefore, developing bioimaging probes to visualize NE levels in the brain is a key to elucidating the pathophysiological process of depression. However, because NE is similar in structure and chemical properties to two other catecholamine neurotransmitters, epinephrine and dopamine, designing an NE-specific multimodal bioimaging probe is a difficult task. In this work, we designed and synthesized the first near-infrared fluorescent-photoacoustic (PA) dual-modality imaging probe for NE (FPNE). The β-hydroxyethylamine of NE was shown to react via nucleophilic substitution and intramolecular nucleophilic cyclization, resulting in the cleavage of a carbonic ester bond in the probe molecule and release of a merocyanine molecule (IR-720). This process changed the color of the reaction solution from blue-purple to green, and the absorption peak was red-shifted from 585 to 720 nm. Under light excitation at 720 nm, linear relationships between the concentration of NE and both the PA response and the fluorescence signal intensity were observed. Thus, the use of intracerebral in situ visualization for diagnosis of depression and monitoring of drug interventions was achieved in a mouse model by fluorescence and PA imaging of brain regions after administration of FPNE by tail-vein injection.

In Vivo Evaluation of a Gallium-68-Labeled Tumor-Tracking Cyanine Dye for Positron Emission Tomography/Near-Infrared Fluorescence Carcinoma Imaging, Image-Guided Surgery, and Photothermal Therapy.

Positron emission tomography (PET)/near-infrared fluorescence (NIRF) dual-modal imaging presents an enticing prospect for tumor diagnosis and surgical navigation. In this study, we developed a novel probe IR808-DOTA for tumor-targeted PET/NIRF imaging, image-guided surgery, and photothermal therapy. This construct had better water solubility and pharmacokinetics than IR808 and had similar photophysical properties, tumor targeting ability, and photothermal anticancer effect to IR808. By a simple labeling process, IR808-DOTA was labeled with gallium-68 and applied as a PET probe for tumor imaging in MCF-7 tumor xenografted mice. IR808-DOTA itself acted as an NIRF imaging agent in the following surgery for intraoperative navigation to aid surgeons in the delineation of tumor margins and visualizing sentinel lymph nodes to facilitate a more thorough tumor resection. Irradiation by laser, IR808-DOTA could prominently inhibit tumor growth in MCF-7 subcutaneous tumor model mice by directly ablating tumor cells, inhibiting tumor proliferation, and promoting tumor cell apoptosis. In summary, 68Ga-DOTA-IR808 could enable a convenient and user-friendly workflow for tumor imaging and guided surgery, and therefore, it may have great prospects for clinical translation as a PET/NIRF dual-modal probe.

Fluorescent Probes for Biological Species and Microenvironments: from Rational Design to Bioimaging Applications.

ConspectusSome important biological species and microenvironments maintain a complex and delicate dynamic balance in life systems, participating in the regulation of various physiological processes and playing indispensable roles in maintaining the healthy development of living bodies. Disruption of their homeostasis in living organisms can cause various diseases and even death. Therefore, real time monitoring of these biological species and microenvironments during different physiological and pathological processes is of great significance. Fluorescent-probe-based techniques have been recognized as one of the most powerful tools for real time imaging in biological samples. In this Account, we introduce the representative works from our group in the field of fluorescent probes for biological imaging capable of detecting metal ions, small bioactive molecules, and the microenvironment. The design strategies of small molecule fluorescent probes and their applications in biological imaging will be discussed. By regulating the design strategy and mechanism (e.g., ICT, PeT, and FRET) of the electronic and spectral characteristics of the fluorescent platforms, these chemical probes show high selectivity and diverse functions, which can be used for imaging of various physiological and pathological processes. Through the exploration of the rational response mechanism and design strategy, combined with a variety of imaging techniques, such as super-resolution imaging, photoacoustic (PA) imaging, etc., we have realized multimode imaging of the important biological analytes from the subcellular level to the in vivo level, which provides powerful means to study the physiological and pathological functions of these species and microenvironments. This Account aims to offer insights and inspiration for the development of novel fluorescent probes for biological imaging, which could provide powerful tools for the study of chemical biology. Overall, we represent a series of turn-on/turn-off/ratiometric fluorescent/PA probes to visually and dynamically trace biological species and microenvironments in cells and even in vivo that seek higher resolution and depth molecular imaging to improve diagnostic methods and clarify new discoveries related to chemical biology. Our future efforts will be devoted to developing multiorganelle targeted fluorescent probes to study the mechanism of subcellular organelle interaction and employing various dual-mode probes of NIR II and PA imaging to investigate the development of related diseases and treat the related diseases at subcellular and in vivo levels.

Liver-Targeted Near-Infrared Fluorescence/Photoacoustic Dual-Modal Probe for Real-Time Imaging of In Situ Hepatic Inflammation.

Early diagnosis of hepatic inflammation is the key to timely treatment and avoid the worsening of liver inflammation. Near-infrared fluorescence (NIRF) probes have high sensitivity but low spatial resolution in lesion imaging, while photoacoustic (PA) imaging has good spatial location information. Therefore, the development of a NIRF/PA dual-modal probe integrated with high sensitivity and spatial location feedback can achieve an accurate early diagnosis of hepatic inflammation. Here, we report an activatable NIRF/PA dual-modal probe (hCy-Tf-CA) for the detection of the superoxide anion (O2·-) in early hepatic inflammation. hCy-Tf-CA showed high selectivity and sensitivity for detecting O2·- fluctuation in vitro. More importantly, by introducing hepatocyte-targeting cholic acid (CA), the probe successfully achieved accurate in situ imaging of acute inflammatory liver injury (AILI) and autoimmune hepatitis (AIH) in vivo. The introduced CA not only promotes the hepatic targeting accumulation of probes but also improves the performance of low background dual-modal imaging in vivo. Therefore, hCy-Tf-CA provides an effective strategy for significantly improving in situ imaging performance and holds great potential for early, sensitive, and accurate diagnosis of hepatic inflammation.

Two birds with one stone: An enzyme-regulated ratiometric fluorescent and photothermal dual-mode probe for organophosphorus pesticide detection

In this study, based on the oxidase activity and photothermal effect of manganese dioxide nanosheets (MnO2 NSs), with thiamine (TH) as the fluorescence response signal and tris (2,2'-bipyridyl) ruthenium (II) hexahydrate as the reference signal, an enzyme-regulated ratiometric fluorescence and photothermal dual-mode probe was constructed for the quantitative detection of organophosphorus pesticide (OPs) residues. OPs reduced the production of the reductive product thiocholine by inhibiting the activity of acetylcholinesterase, thereby regulating the residual amount of MnO2 NSs. With the increase of OPs concentration, the color of the probe solution gradually transitioned from red to blue, and the temperature gradually increased. Using dichlorvos and chlorpyrifos as pesticide models, the developed probes exhibited sensitive responses to OPs in a wide linear range of 0.1–8000 ng/mL. The detection limits of dichlorvos and chlorpyrifos in fluorescence mode were 1.13 × 10−3 ng/mL and 0.86 ng/mL, respectively. The corresponding detection limits in photothermal mode were 1.01 ng/mL and 1.02 ng/mL, respectively. The proposed probe displayed excellent anti-interference and reliability in the analysis of OPs residues in real samples. The dual-mode probe with self-verification function is expected to provide more accurate and robust detection results than the single-mode probe, and has a wider application prospect.

A novel superparamagnetic iron oxide nanoparticles-based SPECT/MRI dual-modality probe for tumor imaging

A novel superparamagnetic iron oxide nanoparticles-based SPECT/MRI dual-modality probe for tumor imaging

A ratiometric near-infrared fluorescence/photoacoustic dual-modal probe with strong donor dithienopyrrole for in vivo nitric oxide detection

Integrating the imaging techniques of near-infrared fluorescence (NIRF) and photoacoustic (PA) can make up for each other and provide more useful medical information. Ratiometric imaging activated by disease-associated biomarkers can further augment imaging specificity. However, very few studies have employed the NIRF/PA dual-modal ratiometric imaging to improve the accuracy and specificity of disease diagnosis to date. In this paper, we present the synthesis of a nitric oxide (NO)-activated ratiometric NIRF/PA dual-modal nanoprobe RAPNP for in vivo NO imaging. The ratiometric imaging function was achieved jointly by a NO/acidity-responsive molecule DTP-BTDA and a nonresponsive fluorophore DTP-BBTD. In these fluorophores, the dithienopyrrole (DTP) moiety had strong electron-donating ability and imparted strong intramolecular charge transfer and relatively long emission wavelengths. The BTDA moiety in DTP-BTDA could be rapidly oxidized by NO under weak acidic environments, achieving the NIRF and PA signal activation. By using RAPNP as a contrast agent, we achieved the ratiometric detection of the endogenous NO in inflammatory bowel disease by NIRF/PA dual-modal imaging. This work provides the first case of the NIRF/PA dual-signal ratiometric probe for the real-time detection of NO in vivo.

A dual-mode green emissive fluorescent probe for real-time detection of doxycycline in milk using a smartphone sensing platform.

Real-time quantitative analysis of tetracyclines is urgently needed to provide consumers with early warning of potential risks. Herein, we report a dual-mode green emissive fluorescent probe, which refers to the liquid mode and the solid mode of electrospun films doped with nitride-doped carbon nanosheets (NCNSs) for real-time detection of doxycycline (DOX). Highly fluorescent NCNSs were prepared by low-temperature solid treatment of urea and sodium citrate. With the addition of DOX, the green emission intensity of NCNSs at 475 nm can be obviously reduced. Method validation exhibited a good linear relationship in 0.05-150 μM between the fluorescence quenching of NCNSs and the concentration of DOX with a limit of detection (LOD) of 0.0127 μM. Furthermore, the immobilization of NCNSs in PAN carriers forming electrospun films stabilizes the green fluorescence of NCNSs. Additionally, electrospun films integrated into a smartphone were developed for real-time detection of DOX with LOD of 0.285 μM. Additionally, DOX in milk was monitored with satisfactory recoveries. Therefore, the integration of the smartphone and electrospun film provides a promising and convenient method for real-time identification of DOX in food analysis.

Design of a near-infrared fluoro-photoacoustic probe for rapid imaging of carboxylesterase in liver injury.

Carboxylesterase (CE) is crucial in metabolizing ester-containing biomolecules and is particularly significant in liver metabolic diseases. Herein, we present the first activatable NIRF/PA dual-mode imaging probe QHD-CE for detection of CE in vitro and in vivo. QHD-CE displays excellent sensitivity and selectivity for CE with a high reaction efficiency (∼90 min). By utilizing QHD-CE, the dynamic changes of CE in drug-induced liver injury and diabetic mice models were monitored.

Construction of an electrochemical-fluorescent dual-mode sensor with a dual-mode signal AgNC probe synthesized from cytosine-rich DNA for OTA detection.

Herein, we have used DNA-silver nanocluster (DNA-AgNC) signal probes with both electrochemical and fluorescent signals for the first time to construct an electrochemical-fluorescent dual-mode sensor. The sensor has an easy-to-prepare dual-signal property combined with the magnetic separation technique for dual-mode detection of ochratoxin A (OTA). In the absence of OTA, the DNA strand used to synthesize AgNCs was not available in the system after magnetic separation. DNA-AgNCs probes could not be synthesized in the system, resulting in low fluorescence and electrochemical signals. In the presence of OTA, it led to the shedding of sulfhydryl-modified and cytosine-rich DNA (C-DNA). DNA-AgNCs probes with high fluorescence and electrochemical signals were formed by adding AgNO3 and NaBH4 to the supernatant after magnetic separation. Dual-mode detection of OTA was achieved by the signal response of fluorescence and electrochemistry. The detection ranges were 2.5 × 10-4-50 ng mL-1 and 2.5 × 10-4-25 ng mL-1 in the fluorescence mode and electrochemical mode with detection limits of 0.11 pg mL-1 and 0.025 pg mL-1, respectively. Meanwhile, the dual-mode sensor displayed better specificity, repeatability and reproducibility than conventional electrochemical and fluorescent single-mode sensors. The results of the spiked peanut and wheat flour detection showed that the fluorescence and electrochemical modes of the sensor exhibited satisfactory average recoveries.

Colorimetric and fluorometric dual-mode determination of hypochlorite based on redox-mediated quenching.

We have successfully created a dual-modal probe, labeled as of iron(ii)-ortho-phenanthroline/N, S@g-CDs, which combines both fluorometric and colorimetric techniques for the accurate and sensitive detection of hypochlorite (ClO-). The mechanism behind this probe involves the fluorescence quenching interaction between nitrogen and sulfur co-doped green emissive carbon dots (N, S@g-CDs) and the iron(ii)-ortho-phenanthroline chelate, utilizing both the inner filter effect and redox processes. As the concentration of ClO- increases, the iron(ii) undergo oxidation to iron(iii) as follows: Fe(ii) + 2HClO = Fe(iii) + Cl2O + H2O, leading to the restoration of N, S@g-CDs fluorescence. Simultaneously, the color of the system transitions gradually from red to colorless, enabling colorimetric measurements. In the fluorometric method with an excitation wavelength of 370 nm, the ClO- concentration exhibits a wide linear correlation with fluorescence intensity ranging from 0.07 to 220 μM. The detection limit achieved in this method is 0.02 μM (S/N = 3). In contrast, the colorimetric method exhibits a linear range of 1.12 to 200 μM, with a detection limit of 0.335 μM (S/N = 3). The proposed selective absorbance for this method is 510 nm. The probe has been effectively utilized for the detection of ClO- in various samples, including water and milk samples. This successful application showcases its potential for determining ClO- in complex matrices, highlighting its broad range of practical uses.

A dual-mode probe based on AIE and TICT effects for the detection of the hypochlorite anion and its bioimaging in living cells.

Based on aggregation-induced emission (AIE) and twisted intramolecular charge transfer (TICT) mechanisms, a fluorescent probe SWJT-12 for the detection of ClO- was designed by using the CN bond as a reactive group. This synthesized probe can react with ClO- in a high aqueous phase, and it shows a large Stokes shift (144 nm) and low biological toxicity. Its limit of detection was calculated to be 0.28 μM. Furthermore, SWJT-12 was successfully used for ratiometric imaging of the exogenous hypochlorite anion in living cells.

Dual-modal molecular imaging and therapeutic evaluation of coronary microvascular dysfunction using indocyanine green-doped targeted microbubbles.

Coronary microvascular dysfunction (CMD), which causes a series of cardiovascular diseases, seriously endangers human health. However, precision diagnosis of CMD is still challenging due to the lack of sensitive probes and complementary imaging technologies. Herein, we demonstrate indocyanine green-doped targeted microbubbles (named T-MBs-ICG) as dual-modal probes for highly sensitive near-infrared (NIR) fluorescence imaging and high-resolution ultrasound imaging of CMD in mouse models. In vitro results show that T-MBs-ICG can specifically target fibrin, a specific CMD biomarker, via the cysteine-arginine-glutamate-lysine-alanine (CREKA) peptide modified on the surface of microbubbles. We further employ T-MBs-ICG to achieve NIR fluorescence imaging of injured myocardial tissue in a CMD mouse model, leading to a signal-to-background ratio (SBR) of up to 50, which is 20 fold higher than that of the non-targeted group. Furthermore, ultrasound molecular imaging of T-MBs-ICG is obtained within 60 s after intravenous injection, providing molecular information on ventricular and myocardial structures and fibrin with a resolution of 1.033 mm × 0.466 mm. More importantly, we utilize comprehensive dual-modal imaging of T-MBs-ICG to evaluate the therapeutic efficacy of rosuvastatin, a cardiovascular drug for the clinical treatment of CMD. Overall, the developed T-MBs-ICG probes with good biocompatibility exhibit great potential in the clinical diagnosis of CMD.