Dual-modality Probe Research Articles

A merocyanine-based dual-mode optical probe for detection of hydrazine and its bioimaging application invitro and vivo.

In this paper, a Merocyanine-based turn-on probe (McyA) has been developed for colorimetric and fluorescent dual-mode detection of N2H4 via an intra-molecular charge transfer (ICT) mechanism. In the presence of N2H4, the probe shows an obvious chromogenic response and fluorescent enhancement. Based on this feature, the synthesized McyA can be applied to quantify N2H4 concentration from 0.12 to 5.0 μM and 0.5-10 μM with a detection limit of 0.042 μM (1.3 ppb, S/N = 3) and 0.140 μM (4.5 ppb, S/N = 3), respectively. Moreover, McyA has also be successfully employed for imaging analysis of N2H4 distribution in different organs from the N2H4 ingested mice model, revealing the potential application of McyA as a powerful fluorescent sensor for tracking detection and risk assessment of hydrazine invivo.

Dual-Modal Imaging-Guided Precise Tracking of Bioorthogonally Labeled Mesenchymal Stem Cells in Mouse Brain Stroke.

Noninvasive and precise stem cell tracking after transplantation in living subject is very important to monitor both stem cell destinations and their in vivo fate, which is closely related to their therapeutic efficacy. Herein, we developed bicyclo[6.1.0]nonyne (BCN)-conjugated glycol chitosan nanoparticles (BCN-NPs) as a delivery system of dual-modal stem cell imaging probes. Near-infrared fluorescent (NIRF) dye Cy5.5 was chemically conjugated to the BCN-NPs, and then oleic acid-coated superparamagnetic iron oxide nanoparticles (OA-Fe3O4 NPs) were encapsulated into BCN-NPs, resulting in Cy5.5-labeled and OA-Fe3O4 NP-encapsulated BCN-NPs (BCN-dual-NPs). For bioorthogonal labeling of human adipose-derived mesenchymal stem cells (hMSCs), first, hMSCs were treated with tetra-acetylated N-azidoacetyl-d-mannosamine (Ac4ManNAz) for generating azide (-N3) groups onto their surface via metabolic glycoengineering. Second, azide groups on the cell surface were successfully chemically labeled with BCN-dual-NPs via bioorthogonal click chemistry in vitro. This bioorthogonal labeling of hMSCs could greatly increase the cell labeling efficiency, safety, and imaging sensitivity, compared to only nanoparticle-derived labeling technology. The dual-modal imaging-guided precise tracking of bioorthogonally labeled hMSCs was tested in the photothrombotic stroke mouse model via intraparenchymal injection. Finally, BCN-dual-NPs-labeled hMSCs could be effectively tracked by their migration from the implanted site to the brain stroke lesion using NIRF/T2-weighted magnetic resonance (MR) dual-modal imaging for 14 days. Our observation would provide a potential application of bioorthogonally labeled stem cell imaging in regenerative medicine by providing safety and high labeling efficiency in vitro and in vivo.

GdVO4:Eu3+,Bi3+ Nanoparticles as a Contrast Agent for MRI and Luminescence Bioimaging.

With the development of multifunctional imaging, gadolinium (Gd)-bearing inorganic nanoparticles (NPs), which were doped with trivalent lanthanide (Ln3+), have been applied in magnetic resonance imaging (MRI) and optical imaging owing to their high payload of Gd3+ ions and specific optical characteristics. In this study, we chose GdVO4 codoped with Eu3+ and Bi3+ as the host material to generate a highly efficient contrast agent (CA) for MRI and long-term luminescence imaging. The new CA emits strong and stable luminescence because of its strong characteristic emissions, resulting from the energy-transfer process from the vanadate groups (VO43–) to the Eu3+ and Bi3+ dopants. Additionally, these NPs provided conspicuous T1 and T2 relaxation time-shortening characteristics, which result in MRI enhancement. GdVO4:Eu3+,Bi3+ NPs were tested on liver tumor-bearing nude mice, and showed improved liver tumor contrast in T2-weighted MR images (T2WI). The dual-modal imaging probe exhibited no cytotoxicity or organ toxicity, reflecting its excellent biocompatibility. Thus, GdVO4:Eu3+,Bi3+ has the potential to be used for bioassays in vitro and liver tumor targeting in vivo. The results reveal the great promise of using the designed GdVO4:Eu3+,Bi3+ NPs as luminescent and MRI dual-mode bioprobes for clinical bioimaging applications.

A solvent-dependent fluorometric dual-mode probe for Pd2+ and ClO− in living cells

A solvent-dependent probe based on rhodamine was designed, and the sensing behaviors were investigated by spectral properties. Especially, the probe exhibited highly sensitive and selective fluorescence enhancement upon addition of Pd2+ in ethanol/PBS (2:8, v/v) and ClO− in DMSO/PBS (1:9, v/v) at physiological range with two kinds of mechanisms. Furthermore, the probe was applied for biological imaging which confirmed that it could be used for monitoring Pd2+ and ClO− in living cells with satisfying results.

Hybrid silica-coated Gd-Zn-Cu-In-S/ZnS bimodal quantum dots as an epithelial cell adhesion molecule targeted drug delivery and imaging system.

Dual-modal imaging probes based on fluorescence (FL) and magnetic resonance (MR) modalities have attracted great attention due to their ability to combine the target specificity and high penetration into body tissues. In this study, we developed a potent nanocarrier with an effective photoluminescent emission and MR imaging capacity to deliver the doxorubicin to breast cancer 4T1 cells. The nanocarrier was fabricated by coating of quantum dots (QDs) with mesoporous silica followed by amine functionalization of the silica surface. Then, the doxorubicin was loaded into the silica pores and biheterofunctional PEG was covalently bound to the surface of core-shell quantum dot mesoporous silica nanoparticles. In order to target the DOX-loaded nanoparticles, the EpCAM DNA aptamer was attached on the surface of the DOX-loaded PEGylated nanoparticles. The synthesized NPs were analyzed for their size distribution, morphology, zeta potential and magnetic susceptibility using HRTEM, SEM and VSM analysis. The QD-encapsulated mesoporous silica revealed spherical shapes with an average particle size of 100 nm. The maximum encapsulation efficacy of doxorubicin in the silica pores was 25%. The in vitro release assessment demonstrated the pH-sensitive release of doxorubicin from the designed formulations. The in vitro cytotoxicity assays indicated that the aptamer targeted nanoparticles showed greater cytotoxicity than both non-targeted NPs and free DOX toward 4T1 and MCF-7 cell lines. The in vivo studies in 4T1 tumor-bearing Balb/c mice demonstrated that EpCAM aptamer could specifically deliver the DOX-loaded nanoparticles into the tumor tissue and cause remarkable inhibition of tumor growth as compared to non-targeted formulation and free DOX. Moreover, the in vivo MR and fluorescent imaging in 4T1 tumor-bearing mice confirmed the accumulation and residence of targeted system in tumor tissue even 24 h post-injection. This work presents a novel system for preparing bimodal imaging theranostic NPs through hybridization of silica and magnetic-fluorescent quantum dots.

Aptamer-mediated N/Ce-doped carbon dots as a fluorescent and resonance Rayleigh scattering dual mode probe for arsenic(III).

Carbon dots doped with N/Ce, N/Eu and N/Tb were prepared by a microwave based hydrothermal technique. The fluorescence of the N/Ce co-doped carbon dots (CDN/Ce) is strongest. They have excitation/emission maxima at 340/441nm. CDN/Ce was characterized by scanning electron microscopy, infrared and fluorescence spectroscopy. On addition of the nucleic acid aptamer (Apt) against arsenic(III) in pH7 solution, the blue fluorescence of the doped carbon dots is partially quenched due to electrostatic interaction. On addition of As(III), it will bind to the aptamer, and the carbon dots are released. Hence, fluorescence becomes gradually restored. In addition, the resonance Rayleigh scattering signal (measured at 340nm) is reduced. This dual-mode assay works in the 0.5-5.8μg·L-1 As(III) concentration range and has a 0.2μg·L-1 detection limit. Graphical abstract Schematic representation of fluorometric and resonance Rayleigh scattering dual mode analysis of As3+ by usingcoupled Apt and CDN/Ce probes. Apt:Aptamer. CD:Carbon dot. Flu:Fluorescence. RRS:Resonance Rayleigh scattering.

Multifunctional nanocomposite clusters enabled by amphiphilic/bioactive natural polysaccharides

Multifunctional nanocomposite clusters have great potential in advanced biological applications, which have mainly been realized via synthetic block-copolymers, silica, and small surfactants. Herein we demonstrate for the first time that bioactive nanocomposite clusters with multifunctionality can be achieved by simple ultrasonication treatment of the mixture of amphiphilic/bioactive natural polysaccharides in aqueous media and hydrophobic NPs in organic phase. We observed that this facile approach is generalizable to obtain nanocomposite hybrid clusters with diverse hydrophobic nanoparticles (NPs), such as hydrophobic magnetic NPs (HyM), gold NPs (HyG), quantum dots (HyQ) and the mixture of HyM/HyG or HyM/HyQ. Magneto-fluorescent hybrid clusters (HyM/HyQ) produced from amphiphilic natural polysaccharides can serve as both dual-mode imaging probes for cell tracking and magnetic actuators that can be magnetically maneuvered inside live cells. To check the bioactivity and biocompatibility of the resulting hybrid clusters, the expression level of genes involved in the cell proliferation and apoptosis in cells incubated with the resulting clusters were also explored. It is noteworthy that the clusters show bioactivity without the use of any additional bioactive materials. Our unique approach would open a new avenue for the utilization of amphiphilic/bioactive natural polysaccharides and provide fresh impetus for the development of novel multifunctional hybrid clusters.

Dual-modality imaging of atherosclerotic plaques using ultrasmall superparamagnetic iron oxide labeled with rhodamine.

Aim: The diagnosis of vulnerable atherosclerotic plaques remains challenging. This study labeled ultrasmall superparamagnetic iron oxidewith rhodamine (USPIO-R) and evaluated USPIO-R for imaging atherosclerotic plaques. Methods: Apolipoprotein E-deficient mice were fed a high-fat diet and underwent MRI before and after an intravenous injection of USPIO-R. Subsequently, an aortic specimen from the mice was removed and sliced for fluorescence imaging and Prussian blue and immunofluorescent staining. Results: T2 signal loss appeared and persisted in the aortic plaque postinjection, and spontaneous fluorescence from the plaque was observed. The accumulated mechanism of USPIO-R by plaque was the macrophage internalization by Prussian blue and immunofluorescence. Conclusion: USPIO-R is a promising dual-modality probe for diagnosing and monitoring vulnerable atherosclerotic plaques.

Iridium(III) and gadolinium(III) loaded and peptide-modified silica nanoparticles for photoluminescence and magnetic resonance (dual) imaging.

The combination of non-invasive fluorescence (FL) and magnetic resonance (MR) imaging can compensate for disadvantages in terms of resolution and sensitivity. However, the preparation of dual-mode probes simultaneously exhibiting strong brightness and high MR response is challenging. A multifunctional nanoprobe was synthesized for targeted photoluminescence (PL) and MR dual-modal imaging. It was obtained by conjugating iridium(III) complexes, gadolinium(III) and the peptide arginine-glycine-aspartate (RGD) onto silica nanoparticles (Ir@SiO2-Gd-RGD NPs). They are highly water soluble, have an average diameter of ~50 nm, and emit strong yellowish green PL (with excitation/emission peaks at 380/572 nm). Simultaneously, the nanoprobes exhibit high MR response with a longitudinal relaxation of 7.16 mM-1 s-1. Instead of simple encapsulation, Ir(III) complexes were covalently conjugated to silica matrix to enhance the chemical and photochemical stability of the nanoprobes. The excellent biocompatibility and PL/MR dual modal imaging capability of the NPs is demonstrated using HeLa cells and mice as models.

Dual-mode colorimetric and fluorometric probe for ferric ion detection using N-doped carbon dots prepared via hydrothermal synthesis followed by microwave irradiation

Dual-mode colorimetry and fluorescence detection methods have gained more attentions in recent years. In this paper, a colorimetric and fluorescent dual-mode probe was constructed based on N-doped carbon dots (CDs) that was synthesized using hydrothermal heating followed by microwave irradiation. The CDs were purified using a polarity-based method followed by a size-based method. The CDs selectively form a purple-colored complex with Fe3+ ions accompanied by quenching of the fluorescence emission. The fluorescence emission of CDs was not affected by common metal cations and anions, but was only complexed and quenched by Fe3+ ions. Cyclic voltammetry and optical spectroscopy were used to measure the HUMO and LUMO levels of the CDs. The fluorescence quenching is due to the transfer of the photo-induced electrons from the excited state of the CDs to the LUMO of Fe3+ ions. The fluorescence lifetime of CDs in the presence and absence of Fe3+ was examined by time-correlated single-photon counting. These results along with changes in the absorption spectra suggest a static fluorescence quenching mechanism. The CDs were used as a dual-readout probe for the colorimetric and fluorescent detection of Fe3+ ions in real samples. The lower limit of detection obtained using colorimetry was 0.5 μM (S/N = 3), while that obtained using fluorimetry was 50 nM. The fluorescence intensity of the CDs is pH independent between 2 and 9, which increases the working range for practical application. Furthermore, the CDs in aqueous solution are photostable, thermostable, and stable under high ionic strength, which makes the probe robust and rugged.

Label-free carbon dots from black sesame seeds for real-time detection of ammonia vapor via optical electronic nose and density functional theory calculation

Synthesis of carbon dots from natural precursors and their use in novel sensing applications currently gain much attention in the carbon dot research community because of its practicality and scaling-up possibility. Herein, carbon dots were synthesized from black sesame seeds via hydrothermal method and used as a dual-mode probe for the detection of ammonia in vapor and solution phases. The size of carbon dots was around 7.6 nm, and they exhibited blue-color emission under UV excitation in solution with a quantum yield of 2%. For the first time, the obtained carbon dots as a sensing layer were then used in optical electronic nose for the real-time, room-temperature detection of ammonia vapor and several volatile organic compounds. Our carbon dots in optical electronic nose could sense ammonia vapor generated from ammonia aqueous solutions with a detection limit of 0.8%v/v. Furthermore, they could also differentiate ammonia in various mixtures, containing methanol and water and from ethylenediamine and triethylamine. The density functional theory calculations were used to confirm the change in optical absorbance of carbon dots when exposed to solvent vapors. The computational results supported the experimental findings well in which the carbon dots and ammonia formed the most stable complex among all vapor molecules computed. A paper-based device was also constructed to prove the practicality and versatility of our carbon dot-based ammonia sensors. In summary, solid-state optical absorption sensing via electronic nose has proved to be a real-time, convenient approach for the detection of ammonia vapor. This work also demonstrates experimentally and computationally that the carbon dots are unique nanomaterials and the ammonia sensors based on carbon dots will be useful in various fields.

Scavenger receptor-AI-targeted ultrasmall gold nanoclusters facilitate in vivo MR and ex vivo fluorescence dual-modality visualization of vulnerable atherosclerotic plaques

Owing to the high morbidity and mortality of cardiovascular diseases resulting from atherosclerosis, developing specific noninvasive diagnostic methods to distinguish vulnerable atherosclerotic plaques becomes urgent and mandatory. Herein, scavenger receptors AI (SR-AI), a secreted biomarker associated with foam macrophages, was selected as a target for identifying vulnerable plaques. A dual-modality imaging probe (PP1-Au@GSH@Gd NCs) was constructed by covalently attaching a peptidic SR-AI ligand, PP1 to gadolinium-integrated gold nanoclusters, which exhibited remarkably improved fluorescence signal and longitudinal relaxivity with highly loaded Au and Gd species. In vitro cellular binding studies showed preferential affinity of PP1-Au@GSH@Gd NCs to activated macrophages in SR-AI-dependent manner. In vivo MR/fluorescence images presented robust and prolonged plaque contrast enhancement in established ApoE−/− mice models thanks to favorable targeting efficacy of PP1-Au@GSH@Gd NCs. Collectively, the noninvasive MR/fluorescence molecular imaging strategy with PP1-Au@GSH@Gd NCs holds great promise for precise clinical diagnosis of vulnerable plaques.

Imaging Probes Used in Multiple Imaging System (Dual Modality Probes)

Imaging Probes Used in Multiple Imaging System (Dual Modality Probes)

Synergistic regulation of effective detection for hypochlorite based on a dual-mode probe by employing aggregation induced emission (AIE) and intramolecular charge transfer (ICT) effects

Since hypochlorite (ClO−) possesses the ability that oxidizes electron-rich objects with accompanying variations in spectroscopic features, we present here an effective strategy for generating new molecular-level probe that will be compatible for application in ClO− detection. This optical sensor has been established on a donor-π-acceptor (D-π-A) electronic structure derived from a pyrene derivative appended by 2-thioxo-dihydro-pyrimidine-4,6-dione (abbreviated as Py-Pd). Specifically, it can serve as a dual-mode sensor which exhibits fluorometric and colorimetric responses to the presence of hypochlorite. The high sensitivity, selectivity, fast response time (30 s) as well as low detection limit (75 nM) have been realized. Extensive spectroscopic analyses support the oxidation cleavage of bridge CC linkage leads to the transformation of Py-Pd to pyrene-2-carbaldehyde (Py-CHO). Such real-time imaging of hypochlorite has been also achieved in live cells and zebrafish model. In this sense, this molecular-based system can be employed as an indicator for early evaluation of optical responses of reactive oxygen species.

UMUC1-Targeting Magnetic Resonance Imaging of Therapeutic Response in an Orthotropic Mouse Model of Colon Cancer.

Noninvasive assessment of chemotherapeutic response in colon cancer would tremendously aid in therapeutic intervention of cancer patients and improve outcomes. The aim of the study was to evaluate the feasibility of a noninvasive assessment of chemotherapeutic response by magnetic resonance imaging utilizing underglycosylated mucin 1 (uMUC1) tumor antigen as a biomarker of therapeutic response in a colon cancer mouse model. The study was performed by applying molecular imaging approach based on targeting uMUC1 with specific dual-modality imaging probe (MN-EPPT). The probe consisted of dextran-coated iron oxide nanoparticles conjugated to the near infrared fluorescent dye Cy5.5 and to a uMUC1-specific peptide (EPPT) and was used for magnetic resonance imaging (MRI) and fluorescence optical imaging. An orthotopic murine model of colon cancer expressing human uMUC1 peptide (MC38 MUC1) was created along with the control model devoid of the antigen (MC38 neo). Animals received chemotherapy with 5-fluorouracil (5-FU) followed by MN-EPPT-enhanced MR and optical imaging. In vivo imaging of animals with uMUC1 expressing tumors after 5-FU therapy showed that the average deltaT2 was reduced by 7.27ms (p = 0.045) compared with animals in control groups indicating lower accumulation of MN-EPPT caused by uMUC1 downregulation. In vivo optical imaging, biodistribution, and fluorescence microscopy confirmed the MRI findings. Interestingly, we found that the group of animals that did not respond to chemotherapy ("progressive disease" per RECIST) showed higher accumulation of MN-EPPT compared to the group of responders ("stable disease") consistent with proliferating tumor cells and increased antigen availability. We believe that in application to over 50% of human cancers expressing uMUC1, our results could provide insight into overall assessment of therapeutic response based on its expression as defined by non-invasive MN-EPPT-enhanced MRI.

Preparation of gadolinium doped carbon dots for enhanced MR imaging and cell fluorescence labeling

Gadolinium doped carbon dots (Gd-CDs) were prepared as a dual-modal imaging agent for enhanced MR imaging and cell fluorescence imaging. The Gd-CDs were synthesized via one-step solvent free technique with Gd-DTPA and l-arginine as the Gd and carbon sources with a quantum yield of 57.78%. The Gd-CDs exhibited good crystal structure, excellent aqueous dispersity, high colloidal stability, intense fluorescence and low cytotoxicity. The bio-TEM images revealed that the Gd-CDs could be easily internalized by cancer cells and escape from the endosomes. Furthermore, the Gd-CDs demonstrated wonderful multi-color fluoresence cell labeling ability at various excitation wavelength and much better MR contrast effect compared with commercial Gd-DTPA with a high r1 relaxivity value 6.27 mM−1s−1. In addition, Gd-CDs exhibited brighter MR signal than Gd-DTPA in the animal MR imaging test. Finally, the Gd-CDs also indicated low long-term toxicity by the serum biochemistry analysis. Thus, these results indicated that Gd-CDs would be an excellent dual-modal imaging probe for enhanced MR imaging and fluorescence imaging.

A photoacoustic and fluorescence dual-mode probe for LTA4H imaging reveals inflammation site in murine

Inflammation widely occurs in various tissues and organs in the human body. Rapid and accurate diagnosis of inflammation is essential to avoid severe complications. This study aims to obtain a non-destructive, fast, and comprehensive tool for the detection of pathogenic sites of inflammation in vivo. A fluorescence and photoacoustic dual-mode imaging probe, Cy-ASP, was first developed to detect inflammatory biomarker LTA4H with good sensitivity and selectivity in living small animal. Furthermore, the relationship between LTA4H and NF-κB in an LPS-induced cell was investigated. This work provides a new idea for the clinical diagnosis of pneumonia and hepatitis and revealing the upstream regulatory mechanism of LTA4H in the pneumonia model.

A near-infrared and two-photon dual-mode fluorescent probe for the colorimetric monitoring of SO2in vitro and in vivo.

SO2 has been recently identified as an essential gas messenger followed by NO, CO and H2S. However, abnormal concentrations of SO2 in our bodies can cause many diseases. Thus, the real-time monitoring of SO2 to well define the generation, physiological and pathological functions of SO2 is urgently needed. In this work, we developed a novel SO2 fluorescent probe on the basis of the conjugation of semi-cyanine and coumarin derivate dyes with superior features, such as near-infrared (NIR) and two-photon dual-mode monitoring, a large Stokes shift (175 nm), ultrafast response towards SO2 (within 10 s), high selectivity and photostability. Furthermore, this probe could sense SO2 by dual colorimetric and fluorescence means. In biological imaging, the probe was able to trace exogenous and endogenous SO2 in living cells, mitochondria, E. coli, zebrafish and mice under an NIR and two-photon dual-mode. These results demonstrated that the probe has strong potential for studying the physiological and pathological functions of SO2in vitro and in vivo.

A colorimetric and fluorescent dual-modal displacement probe based on host-assisted modulation of intramolecular charge transfer and deaggregation.

A new colorimetric and fluorescent dual-modal displacement probe was developed based on a supramolecular host-guest complex of cucurbit[8]uril (CB8) and a new functionalized perylene derivative involving macrocycle encapsulation that modulated intramolecular charge transfer and deaggregation.

GSH Activated Biotin-tagged Near-Infrared Probe for Efficient Cancer Imaging.

Tumor imaging tools with high specificity and sensitivity are needed to aid the boundary recognition in solid tumor diagnosis and surgical resection. In this study, we developed a near infra-red (NIR) probe (P6) for in vitro/in vivo tumor imaging on the basis of the dual strategy of cancer cell targeting and stimulus-dependent activation. The selective imaging capacity towards cancer cells of P6 was thoroughly investigated, and the potential mechanisms of endocytosis were preliminary explored.Methods: GSH-activated biotin labelled NIR probe (P6) was designed, synthesized and characterized. The GSH responsive properties were systematically illustrated through UV-vis, fluorescent tests and LC-MS analysis. In vitro fluorescent imaging of probe P6 was collected in various living cancer cell lines (i.e. SW480, HGC-27, H460, BxPC-3, KHOS) and normal cell lines (i.e. BEAS-2B, HLF-1, THP1) under confocal laser scanning microscopy. Probe P6 was further applied to image primary human cancer cells which were freshly isolated from the peritoneal carcinoma and rectal cancer patients. Serial sections of human tumor tissues were collected and sent for H&E (hematoxylin-eosin) staining and P6 imaging. Live fluorescent and photoacoustic imaging were used to investigate the in vivo imaging of P6 in both tumor and normal tissues in HGC-27 and KHOS xenograft model.Results: Probe P6 could be recognized and transported into cancer cells by tumor specific biotin receptors and efficiently be triggered by GSH to release fluorophore 4. In fact, the cellular uptake of P6 could be partially blocked by the addition of free biotin. Furthermore, probe P6 could image various cancer cell lines, as well as primary cancer cells, exhibiting a ten-fold increase in fluorescence intensity over normal cells. In freshly dissected cancer tissues, P6 fluorescent imaging distinguished the cancerous area under confocal laser scanning microscopy, which was exact the same area as indicated by H&E staining. We also found that P6 exhibited superior selectivity against cancer tissues by local injection.Conclusion: In this study, we developed a dual-modal NIR probe P6 with enhanced cellular uptake into cancer cells and environmental stimulus triggered fluorescence. Our strategy provided a novel insight into the development of imaging tools that could be potentially used for fluorescent image-guided cancer boundary recognition and possibly cancer diagnosis.