Near-infrared Fluorescent Nanoprobes Research Articles

Construction of a novel near-infrared fluorescent Nile blue@MOF nanoprobe for imaging mitochondrial ATP in living cells.

A near-infrared fluorescent nanoprobe consisting of Nile blue-capped ZIF-90 is first proposed for real-time imaging of mitochondrial ATP. Owing to the strong binding of ATP with Zn2+, the structure of the probe is disrupted, leading to the release of fluorescent NB.

A nitroreductase-responsive nanoprobe with homogeneous composition and high loading for preoperative non-invasive tumor imaging and intraoperative guidance

Tumor microenvironment (TME)-activatable probes have been proven to effectively increase signal-to-background ratios (SBRs) and improve the success rate of complete tumor resection. However, many fluorescence probes have to be loaded into a nanocarrier for tumor targeted delivery, which consequently encounters poor drug loading, heterogeneous composition and non-encapsulated drug aggregates occurred during nanoformulation fabrications. Herein, a nitroreductase (NTR)-activated “OFF-ON” near-infrared fluorescence nanoprobe, named NanoBodipy, was synthesized by the spontaneous self-assembling of NTR-responsive dye-polyethylene glycol (PEG) amphiphilic polymer in water. The NTR-responsive dye acted as the hydrophobic segment in the amphiphilic polymer, yielding a homogeneous composition and a high loading of 12.2 wt% (according to calculation) in the synthesized NanoBodipy. The synthesized NanoBodipy can efficiently accumulate in tumors via the enhanced permeability and retention (EPR) effect, enabling non-invasive tumor-targeted fluorescence imaging and guiding complete tumor resection. Once the synthesized NanoBodipy entered the tumor cells, they dissociated and were activated by overexpressed NTR. With the real-time fluorescence guide of NanoBodipy, complete tumor resection surgery was performed successfully.

Universal Near-Infrared Fluorescent Nanoprobes for Detection and Real-Time Imaging of ATP in Real Food Samples, Living Cells, and Bacteria.

Adenosine triphosphate (ATP), an essential metabolite for active microorganisms to maintain life activities, has been widely regarded as a marker of cell activity and an indicator of microbial contamination. Herein, we designed two near-infrared (NIR) fluorescent nanoprobes named CYA@ZIF-90 and CYQ@ZIF-90 by encapsulating the NIR dye CYA/CYQ in ZIF-90 for the rapid detection of ATP. Between them, nanoprobe CYA@ZIF-90 can achieve higher NIR emission (702 nm) and rapid detection (2 min). Based on the superior spatiotemporal resolution imaging of ATP fluctuations in living cells, the applicability of CYA@ZIF-90 for imaging and detection of ATP in living bacteria was explored for the first time. The nanoprobe indirectly realizes the quantitative detection of bacteria, and the detection limit can be as low as 74 CFU mL-1. Therefore, the prepared nanoprobe is expected to become a universal ATP sensing detection tool, which can be further applied to evaluate cell apoptosis, cell proliferation, and food-harmful microbial control.

Viscosity-triggered near-infrared fluorescence nanoprobe for in vivo non-invasive diagnosis of cancer

A universal and non-invasive approach for cancer diagnosis is desired to lessen the burden of cancer mortality. In this work, we exploited viscosity in the cancer microenvironment as a diagnosis indicator and designed a universal probe, the CBT-Q (4-(2-(5-(9-(4-aminophenyl)-9H-carbazol-3-yl) thiophen-2-yl)vinyl)-1-ethylquinolin-1-ium) nanoprobe, for detecting viscosity variation in the cells, plasma, and solid tumor-mice to obtain a cancer diagnosis. The near infrared (NIR) fluorescence of CBT-Q was specifically triggered due to a change in its structure from a flexible to a rigid one in the presence of a higher viscosity agent, such as a cancer microenvironment or cancer patient plasma. The Stokes shift of CBT-Q nanoprobe (CBT-Q-N) could be up to 178 nm, enabling the diagnosis of cancer with a low biological fluorescent background. Not only could the CBT-Q-N remain in cells for 72 h, but detect the changes in cell viscosity induced by various models. Also, the CBT-Q-N differentiated early and terminal tumor mice via the fluorescent intensity of plasma viscosity. The CBT-Q-N enables non-invasive recognition of tumors in vivo by fluorescence imaging. Hence, this work is beneficial to increase the understanding of tumor-related viscosity, which will facilitate a new universal strategy for present cancer diagnostics.

Detection and Bioimaging of Glutathione in Cells via a Turn-On Near-Infrared Fluorescent Nanoprobe Composed of Ag2S Quantum Dots and CoOOH Nanosheets

The variations of the microenvironment in cells are always associated with changes in the concentrations of some active species. However, visual detection of these species is still a challenge. In this work, near-infrared (NIR)-emitting fluorescent Ag2S quantum dots (Ag2S QDs) were synthesized via a rapid microwave reaction under normoxic conditions, which were utilized as sensitive fluorescent nanoprobes in sensing and bioimaging of glutathione (GSH) combined with CoOOH nanosheets (CoOOH NSs). The negatively charged Ag2S QDs can easily and effectively attach to the surface of CoOOH NSs to form the Ag2S QD/CoOOH nanoprobe through electrostatic interactions, accompanied by the quenching of the fluorescence of Ag2S QDs at 685 nm via the inner-filter effect (IFE). However, upon the addition of GSH, the fluorescence of Ag2S QDs was recovered due to the reduction of CoOOH NSs into Co2+ by GSH. Meanwhile, the fluorescent emission wavelength shifts slightly, which may result from the ligand exchange reaction between GSH and d-penicillamine (DPA) to form comodified Ag2S QDs. Based on the low toxicity and high tissue penetration depth of the NIR fluorescence of the Ag2S QDs and the good biocompatibility of CoOOH NSs, the nanoprobe composed of Ag2S QDs and CoOOH NSs was successfully applied in bioimaging, which can distinguish the normal cells and cancer cells, the semiquantitative content of endogenous and exogenous GSH. The as-developed strategy not only provides a simple, convenient, cost-effective, and rapid platform for the diagnosis of clinical diseases related to GSH but shows great prospects in fluorescence-assisted surgery.

Near-Infrared Fluorescent Nanoprobes for Adenosine Triphosphate-Guided Imaging in Cancer and Fatty Liver Mice.

Adenosine triphosphate (ATP), as an indispensable biomolecule, is the main energy source of cells and is used as a marker for diseases such as cancer and fatty liver. It is of great significance to design a near-infrared fluorescent nanoprobe with excellent performance and apply it to various disease models. Here, a near-infrared fluorescent nanoprobe (ZIF-90@SiR) based on a zeolitic imidazole framework is proposed. The fluorescent nanoprobes are synthesized by encapsulating the dye (SiR) into the framework of ZIF-90. Upon the addition of ATP, the structure of the ZIF-90@SiR nanoprobe is disrupted and SiR is released to generate near-infrared fluorescence at 670 nm. In the process of ATP detection, ZIF-90@SiR shows high sensitivity and good selectivity. Moreover, the ZIF-90@SiR nanoprobe has good biocompatibility due to its low toxicity to cells. It is used for fluorescence imaging of ATP in living cells and thus distinguishing normal cells and cancer cells, as well as distinguishing fatty liver cells. Due to excellent near-infrared fluorescence properties, the ZIF-90@SiR nanoprobe can not only distinguish normal mice and tumor mice but also differentiate normal mice and fatty liver mice for the first time.

A near-infrared fluorescent nanoprobe for senescence-associated β-galactosidase sensing in living cells.

A near-infrared fluorescent nanoprobe based on semiconducting polymer nanoparticles (SPNs) for the detection of senescence-associated β-gal (SA-β-gal) is developed. Benefiting from the intrinsic lysosome-locating feature, this probe can be successfully used for the visualization of SA-β-gal in living cells.

Sensitive NIR Fluorescence Identification of Bacteria in Whole Blood with Bioorthogonal Nanoprobes for Early Sepsis Diagnosis.

Sepsis is one of the leading causes of death worldwide. The disease progression of sepsis is very fast, and there is a 7-9% increase in mortality every hour. Therefore, rapid and sensitive detection of pathogenic bacteria is crucial for the timely treatment of sepsis as well as the reduction of mortality. Herein, we present a sensitive near-infrared (NIR) fluorescence identification and a rapid magnetic capture based on bioorthogonal nanoprobes for the detection of multiple bacteria in whole blood. The nanoprobes with NIR fluorescence/magnetic properties were modified with dibenzocyclooctyne groups and used to capture and recognize the bacteria via bioorthogonal reaction. The magnetic nanoprobes showed superparamagnetic properties with a saturation magnetization as high as 63 emu/g. Through clicking with the azide groups inserted on the bacteria walls by metabolic engineering, the bioorthogonal magnetic nanoprobes allow fast and broad-spectrum capture of both Gram-positive and Gram-negative bacteria. The bioorthogonal NIR fluorescent nanoprobes with a maximum emission at 900 nm can effectively avoid background interference, further enabling sensitive identification of the bacteria in whole blood. The detection limit was as low as 4 CFU/mL in less than 2.5 h and the nanoprobes were successfully applied to the detection of bacteria in blood samples from the patients with sepsis, showing the potential application in early sepsis diagnosis and clinical studies.

ATP fluorescent nanoprobe based on ZIF-90 and near-infrared dyes for imaging in tumor mice

ATP is the direct source of energy required for all life activities and can be used as a cancer biomarker. Although several fluorescent probes are developed to detect ATP, most of them have the problem of poor stability or short emission that is not suitable for in-vivo imaging. Herein, three ATP-responsive near-infrared (NIR) fluorescent nanoprobes are prepared by encapsulating NIR fluorescent dyes in the pores of ZIF-90. Among them, CP@ZIF-90 nanoprobe has the longest emission wavelength (705 nm) and the largest fluorescence enhancement (32-fold) for ATP detection. Moreover, the nanoprobe has excellent photostability and chemical stability. It is worth to point that carboxyl group in fluorescent dyes plays the important role, which provides a direction for the construction of NIR fluorescent nanoprobes based on ZIF-90. In addition, CP@ZIF-90 has good biocompatibility and the ability to enrich in tumor. It is successfully used for fluorescence imaging of endogenous and exogenous ATP levels in real-time in living cells (293 T and CT26 cells). More importantly, CP@ZIF-90 has shown excellent ability in distinguishing normal mice from tumor mice, which make it have the possibility of being an effective technique for cancer early diagnosis in vivo by imaging ATP.

A Novel NIR Fluorescent Nanoprobe Targeting HER2-Positive Breast Cancer: Tra-TTR-A.

TTRE, a photosensitizer molecule, has excellent biofluorescence imaging performance and effective antitumor properties for breast cancer. However, its application in breast cancer treatment is limited due to poor tumor selectivity and lack of targeting ability. In this study, TTRE and trastuzumab were combined to synthesize Tra-TTR-A, a novel near-infrared fluorescent nanoprobe for HER2 positive breast cancer. The targeting and antitumor abilities of Tra-TTR-A in breast cancer were also investigated. Like TTRE, Tra-TTR-A has a stable structure with remarkable optical properties and in vivo imaging capacity. However, Tra-TTR-A not only inhibits tumor growth by generating reactive oxygen species but also kills tumor cells by trastuzumab. In this study, Tra-TTR-A, a new type of near-infrared fluorescent nanoprobe that targets HER2-positive breast cancer, was successfully synthesized. Tra-TTR-A could be used in in vivo imaging, targeted photodynamic therapy, and diagnosis and treatment for breast cancer.

Azo-Based Hypoxia-Responsive Self-Assembly Near-Infrared Fluorescent Nanoprobe for In Vivo Real-Time Bioimaging of Tumors.

Hypoxia is an obvious characteristic of cancer, especially solid tumors. which may give rise to the expansion of invasion and metastasis. Exploring near-infrared (NIR) nanoprobes that could accurately evaluate the degree of hypoxia will contribute to the assessment of the degree of malignant neoplasms, so as to adopt more accurate and individualized treatment options Here, we have developed a self-assembled NIR organic nanoprobe to specifically and authoritatively detect the oxygen concentration in vivo and in vitro to evaluate the level of hypoxia. The organic nanoprobe mainly contains two motifs: a fluorophore moiety NRh-NH2 for NIR fluorescence imaging and hypoxia-sensitive moiety Azonaphthalene derivatives for quenching NIR emissions, detecting oxygen in hypoxic regions and improving the hydrophilicity. The nanoprobes were used for detection of oxygen in a variety of living cells under different conditions and real-time bioimaging of neoplasms in live mice. This design strategy provides ideas for the development of nanoprobes for the diagnosis of tumors and other hypoxia-related diseases.

A near−infrared fluorescent sensor based on the architecture of low−toxic Ag2S quantum dot and MnO2 nanosheet for sensing glutathione in human serum sample

Near−infrared (NIR) emitting Ag2S quantum dots (QDs) are excellent fluorescent nanoprobes for bioassays with low toxicity. A novel fluorescent sensing platform which employing NIR fluorescent Ag2S QDs and MnO2 2D nanosheets as NIR emitters and quenchers is designed for rapid and selective determination of glutathione (GSH). A facile and efficient approach was demonstrated for the synthesis of NIR fluorescent Ag2S QDs with the emission of 845 nm. Then the NIR fluorescent nanoprobe of Ag2S QDs−MnO2 nanosheets is obtained by adsorbing Ag2S QDs onto the surface of MnO2 nanosheets which have atomically thick two−dimensional structure and high specific surface area. And the NIR fluorescence of Ag2S QDs is quenched by the MnO2 nanosheets. The presence of GSH could reduce MnO2 to Mn2+ that results in the restoration of NIR fluorescence for Ag2S QDs. The NIR fluorescent nanoprobe could be used for highly selective detection of GSH. Also a low detection limit of 60 μmol/L was obtained. Because NIR fluorescence of the Ag2S QDs can efficiently reduce the interferences from background scattering and autofluorescence. The NIR fluorescent nanoprobe was directly applied to monitor the GSH level in human serum sample with high accuracy and precision.

Calcium-binding near-infrared fluorescent nanoprobe for bone tissue imaging

We report a self-assembled calcium-binding nanoprobe which emits a near-infrared fluorescence (NIRF) signal. We have designed a calcium-binding NIRF nanoprobe by chemically coupling alendronate (ALN), a specific targeting ligand, and NIRF-emitting Cy5.5-labeled dibenzocyclooctyne, to the two respective ends of azide-polyethylene glycol-NHS ester. Prepared ALN-PEG-Cy5.5 forms the self-assembled nanostructures and has high affinity for calcium phosphates-containing bone minerals. In addition, ALN-PEG-Cy5.5 can be employed to visualize intracellular calcium ion levels in vitro as well as normal bone tissues in vivo. These results suggest that our calcium-binding NIRF nanoprobe has a promising potential for calcium imaging in vitro and in vivo.

Biomineralization synthesis of a near-infrared fluorescent nanoprobe for direct glucose sensing in whole blood.

A near-infrared (NIR) fluorescent nanoprobe that enables to circumvent the interference of background absorption and fluorescence in whole blood was developed for the direct sensing of blood glucose. Here, NIR fluorescent protein (iRFP) and glucose oxidase (GOx) were collectively deployed as the templates for the biomineralization of Mn2+ to prepare a NIR fluorescent nanoprobe (iRFP-GOx-MnO2 nanoparticles, iRGMs), in which the fluorescence of iRFP was effectively quenched by MnO2via energy transfer. When the iRGMs were mixed with whole blood samples, GOx can convert blood glucose into gluconic acid, as well as H2O2, which will reduce MnO2 and decompose the iRGMs. As a result, the NIR fluorescence of iRFPs was restored, providing a fluorometric assay for the direct detection of blood glucose. Owing to the high efficiency of the cascade reaction and the low background interference of the NIR fluorescence signal, accurate and rapid analysis of the glucose levels in whole blood samples was achieved using the iRGMs. Moreover, an iRGM-based paper device that only requires 5 microliters of samples was also demonstrated in the direct assay of blood glucose without any pretreatment, affording an alternative approach for the accurate monitoring of blood glucose levels.

Bovine serum albumin encapsulation of near infrared fluorescent nano-probe with low nonspecificity and cytotoxicity for imaging of HER2-positive breast cancer cells

Breast cancer with HER2 overexpressing type links to malignant tumor growth and poor clinical outcome. Successful development of sensitive and selective nano-probe for identification of HER2-positive breast cancer cells is of great importance for breast cancer early diagnosis, subtype classification, and treatment planning. Herein, we report a HER2 antibody conjugated near infrared (NIR) emitted MnCuInS/ZnS qumtun dots (QDs) encapsulated bovine serum albumin (BSA) nano-probe for accurately targeted imaging of HER2-positive breast cancer cells. This NIR nano-probe shows good biocompatibility, low nonspecificity and cytotoxicity, high colloidal stability, and allows HER2-positive breast cancer cell identification with good selectivity. The practicality of this targeted NIR fluorescent nano-probe was proved by successful identifying HER2-positive breast cancer cells from HER2-negative breast cancer cells, which indicates that it can be efficiently applied in selective screening of HER2 overexpressing cancer cells, and provide a platform for the strategy design on the distinction of different breast cancer subtypes.

Targeted Myocardial Hypoxia Imaging Using a Nitroreductase-Activatable Near-Infrared Fluorescent Nanoprobe.

Development of a highly selective and sensitive imaging probe for accurate detection of myocardial hypoxia will be helpful to estimate the degree of ischemia and subsequently guide personalized treatment. However, an efficient optical approach for hypoxia monitoring in myocardial ischemia is still lacking. In this work, a cardiomyocyte-specific and nitroreductase-activatable near-infrared nanoprobe has been developed for selective and sensitive imaging of myocardial hypoxia. The nanoprobe is a liposome-based nanoarchitecture which is functionalized with a peptide (GGGGDRVYIHPF) for targeting heart cells and encapsulating a nitrobenzene-substituted BODIPY for nitroreductase imaging. The nanoprobe can specifically recognize and bind to angiotensin II type 1 receptor that is overexpressed on the ischemic heart cells by the peptide and is subsequently uptaken into heart cells, in which the probe is released and activated by hypoxia-related nitroreductase to produce fluorescence emission at 713 nm. The in vitro response of the nanoprobe toward nitroreductase resulted in 55-fold fluorescence enhancement with the limit of detection as low as 7.08 ng/mL. Confocal fluorescence imaging confirmed the successful uptake of nanoprobe by hypoxic heart cells and intracellular detection of nitroreductase. More significantly, in vivo imaging of hypoxia in a murine model of myocardial ischemia was achieved by the nanoprobe with high sensitivity and good biocompatibility. Therefore, this work presents a new tool for targeted detection of myocardial hypoxia and will promote the investigation of the hypoxia-related physiological and pathological process of ischemic heart disease.

An Aptamer-Based Near-Infrared Fluorescence Nanoprobe for Detecting and Imaging of Phospholamban Micropeptide in Cardiomyocytes

A growing body of evidence indicates that micropeptides encoded by long noncoding RNAs (lncRNAs) act independently or as regulators of larger proteins in fundamental biological processes, especially in the maintenance of cellular homeostasis. However, due to their small size and low intracellular expression, visual monitoring of micropeptides in living cells is still a challenge. In this work, we have designed and synthesized an aptamer-based near-infrared fluorescence nanoprobe for fluorescence imaging of phospholamban (PLN), which is an intracellular micropeptide that affects calcium homeostasis, and is closely associated with human heart failure in the clinic. The nanoprobe could respond specifically to PLN with excellent selectivity, high sensitivity, good nuclease stability, and biocompatibility, and it was successfully applied for imaging of changes in PLN levels in cardiomyocytes and in frozen sections of heart tissues. Further combined with clinical myocardial biopsy, we believe that the developed nanoprobe should be of great significance in later molecular pathology study of heart failure, which may help with diagnosis of early heart failure in the future. More importantly, for the first time nanoprobes were applied to visually monitor the changes of micropeptides in living cells and in frozen tissue sections, and the design concept of the aptamer-based nanoprobe can be extended to fluorescence detection of other micropeptides.

Biodegradable nanoprobe based on MnO2 nanoflowers and graphene quantum dots for near infrared fluorescence imaging of glutathione in living cells.

Near infrared (NIR) emitting semiconductor quantum dots can be excellent fluorescent nanoprobes, but the poor biodegradability and potential toxicity limits their application. The authors describe a fluorescent system composed of graphene quantum dots (GQDs) as NIR emitters, and novel MnO2 nanoflowers as the fluorescence quenchers. The system is shown to be an activatable and biodegradable fluorescent nanoprobe for the "turn-on" detection of intracellular glutathione (GSH). The MnO2-GQDs nanoprobe is obtained by adsorbing GQDs onto the surface of MnO2 nanoflowers through electrostatic interaction. This results in the quenching of the NIR fluorescence of the GQDs. In the presence of GSH, the MnO2-GQDs nanoprobe is degraded and releases Mn2+ and free GQDs, respectively. This gives rise to increased fluorescence. The nanoprobe displays high sensitivity to GSH and with a 2.8μM detection limit. It integrates the advantages of NIR fluorescence and biodegradability, selectivity, biocompatibility and membrane permeability. All this makes it a promising fluorescent nanoprobe for GSH and for cellular imaging of GSH as shown here for the case of MCF-7 cancer cells. Graphical abstract A biodegradable NIR fluorescence nanoprobe (MnO2-GQDs) for the "turn-on" detection of GSH in living cell was established, with the NIR GQD as the fluorescence reporter and the MnO2 nanoflower as the fluorescence quencher.

Near-infrared fluorescent nanoprobes for highly sensitive cyanide quantification in natural waters

Near infrared (NIR) emitting Ag2S quantum dots have been synthesized, characterized and evaluated for chemical sensing applications. After their optical characterization, it was observed that the Ag2S quantum dots present both, excitation and emission in the NIR region, and an excellent quantum yield of 33.2%. These features are of great value for many biological applications, since autofluorescence of biological tissues or cells is minimized, and also for environmental applications, where other fluorescent concomitant species with excitation and emission in the ultraviolet-visible region might be present.Different purification procedures were evaluated in order to obtain a stable and homogeneous population of nanoparticles, which is necessary to perform quantitative analysis (e.g.: mass spectrometry-based applications), as well as to obtain a narrow NIR emission spectrum for optical applications.Comprehensive characterization using X-ray diffraction, transmission electron microscopy, and asymmetric flow field flow fractionation coupled to inductively coupled plasma-mass spectrometry has been performed to obtain parameters not easily achieved and of great interest in different research areas, such as the nanoparticle concentration NIR-emitting nanoparticles, and the surface ligand density, which directly affects to the interactions of the nanoparticles with their close environment, including unspecific adsorptions, cellular uptake, macrophage interaction, etc.Finally, the capability for sensing analytes of environmental interest based on direct-interactions of a reactive compound with the surface of the nanoparticle has been also evaluated. Quenching of the NIR emission upon interaction of the Ag2S quantum dots with cyanide ions was observed. Hence, a rapid, selective and highly sensitive methodology was developed for the detection of cyanide in natural waters.

Aggregation-Induced Emission-Active Near-Infrared Fluorescent Organic Nanoparticles for Noninvasive Long-Term Monitoring of Tumor Growth.

Effective long-term monitoring of tumor growth is significant for the evaluation of cancer therapy. Aggregation-induced emission-active near-infrared (NIR) fluorescent organic nanoparticles (TPFE-Rho dots) are designed and synthesized for long-term in vitro cell tracking and in vivo monitoring of tumor growth. TPFE-Rho dots display the advantages of NIR fluorescent emission, large Stokes shift (∼180 nm), good biocompatibility, and high photostability. In vitro cell tracing studies demonstrate that TPFE-Rho dots can track SK-Hep-1 cells over 11 generations. In vivo optical imaging results confirm that TPFE-Rho dots can monitor tumor growth for more than 19 days in a real-time manner. This work indicates that TPFE-Rho dots could act as NIR fluorescent nanoprobes for real-time long-term in situ in vivo monitoring of tumor growth.