Multifunctional Probe Research Articles

Multifunctional fluorescence probe for simultaneous detection of viscosity, polarity, and ONOO− and its bioimaging in vitro and vivo

Intracellular microenvironment (viscosity and polarity) and peroxynitrite ions (ONOO−) are involved in maintaining cell morphology, cell function, and signaling so that it is crucial to explore their level changes in vitro and vivo. In this work, we designed and synthesized a mitochondria-targeted fluorescence probe XBL for monitoring the dynamic changes of viscosity, polarity, and ONOO− based on TICT and ICT mechanism. The fluorescence spectra showed obvious changes for polarity at 500 nm as well as ONOO− and viscosity at 660 nm, respectively. The XBL can image simultaneously viscosity, polarity, and ONOO− in cells, and the results showed excess ONOO− leaded to the increase of viscosity in mitochondrial. The ferroptosis process was accompanied by increase of intracellular viscosity and ONOO− levels (or decrease of polarity), which allowed us to better understand the relevant physiological and pathological processes. The XBL can distinguish normal cells and cancerous cells by the fluorescence intensity changes in green and red channels, and image viscosity in inflamed mice. Thus, XBL can provided the chemical tool to understand the physiological and pathological mechanisms of disease by simultaneous detection of viscosity, polarity and ONOO−.

Copper-doped Lanthanide Coordination Polymers as Luminescent Nanoenzyme for Ratiometric Sensing of H2O2 and Glutathione.

Design and fabrication of integrated multifunctional probes with intrinsic catalytic and detection abilities is of great importance to simplify the operation in biosensing application with high sensitivity. Herein, dual-emitting lanthanide coordination polymers (Ln-CPs) were facilely prepared by self-assembly of guanine diphosphate (GDP), terephthalic acid (TA), Tb3+ and Cu2+ designated as Tb/Cu-GDP/TA CPs. The doped Cu2+ endowed CPs with obviously enhanced peroxidase mimicking activity compared with free Cu2+. In the presence of H2O2, the probe catalyzed the oxidation of TA generating a new blue fluorescent product, while the fluorescence of Tb3+ decreased simultaneously. Therefore, a new sensitive ratiometric fluorescent sensor for H2O2 has been developed with a good linear range from 0.01 to 300μM and limit of 1.62nM. Moreover, the proposed platform could be extended to GSH ratiometric assay in the presence of H2O2, and interestingly, the detection performance could be easily adjusted by adding different concentration of H2O2. This work will facilitate the development of luminescent nanoenzymes based on Ln-CPs to construct the simple ratiomatric sensing platform.

Dual-response fluorescent probe for simultaneously detecting HOCl and Zn2+ in environmental water samples and evaluating the oxidative stress in the zebrafishes induced by pollutants via fluorescence imaging

Both of hypochlorous acid (HOCl) and Zn2+ ions play important roles in fundamental biological processes. They not only simultaneously exist in the biological organisms, but also coexist in the environment. Thus, developing a novel method for simultaneous detection of HOCl and Zn2+ is very necessary. Herein, the nitrogen- and sulfur-codoped carbon dots (N,S-CDs) were synthesized through a simple and rapid microwave method, it emits dual-emission fluorescence centered at 452 nm and 685 nm, which has specific recognition to HOCl and Zn2+, respectively, and they do not interfere with each other. A dual-emission and dual-response fluorescent probe was thus developed for the simultaneous detection of HOCl and Zn2+ in the environment and fluorescence imaging in the zebrafishes. The limits of detection for HOCl and Zn2+ are 27.0 nM and 13.0 nM, respectively. It has been successfully applied for the simultaneous determination of HOCl and Zn2+ in real water samples. The sensing mechanisms of the N,S-CDs to HOCl and Zn2+ were also discussed in detail. Moreover, the fluorescent probe not only can be used to real-time dynamic monitoring of HOCl and Zn2+ in the zebrafishes, but also can be applied to evaluate the oxidative stress in the zebrafishes induced by pollutions via fluorescence imaging. This work provided a new strategy for developing multifunctional fluorescent probes, and a potential application prospect for environmental monitoring and evaluating the health risks of environmental pollutants to organisms.

Multi-functional ratiometric detection based on dual-emitting N-doped carbon dots

Ratiometric fluorescence probes based on multi-emission carbon dots improve accuracy and sensitivity on detecting various environment issues. Herein, a novel dual-emitting N-doped carbon dots (N-CDs) was synthesized from citric acid and urea via a solvothermal method in N,N-dimethylformamide (DMF). The blue and orange emissions of N-CDs in water were modulated, and pure white light-emitting with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.33) was achieved. The two PL centers behaved differently for Fe3+, Cu2+ and Ag+ ions, with the limit of detection (LOD) of ppm as fluorescence probes. Additionally, N-CDs displayed unique solvatochromism phenomenon. A new green emission appeared in organic solvents and gradually quenched with the increase of solvent polarity. The ratiometric PL displayed an excellent linear response for detecting water, and the LOD was between 0.003 % and 0.3 % in DMF, ethanol, isopropanol and N-methylpyrrolidone. Furthermore, N-CDs exhibited pH-sensitive response in the range of 4.0–7.0 and temperature-dependent response during heating–cooling cycles between 15 and 70 °C. A simple, efficient and reliable multi-functional ratiometric probe for detecting metal ions, water content, pH and temperature simultaneously was realized. However, there is a need for future application research to overcome the limitation imposed by the excitation wavelength of 330 nm.

A novel quinoxaline-based multifunctional probe: Sensitive and selective naked-eye detection of Fe3+ and fluorescent sensing of Cu2+ and its application

A new quinoxaline derivative (QM: 6-methyl-2,3-di(quinoline-2-yl)quinoxaline) was synthesized as a colorimetric and fluorescent chemosensor for detecting Fe3+ and Cu2+ ions. QM can selectively detect Fe3+ among a number of essential cations and showed an obvious colorimetric response (colorless to yellow) in the presence of Fe3+ ions and considerable fluorescence quenching response towards Cu2+ ions. The molar ratio and Job plot showed a 1:1 stoichiometric ratio for the QM-Fe3+ and QM-Cu2+ complexes. The binding constants for QM-Fe3+ and QM-Cu2+ were found to be 3.335 × 105 and 2.230 × 103 M−1, respectively, using the Benesi-Hildebrand method. The quenching rate constant (Ksv) for QM-Cu2+ was 18.8 × 103 M−1 using the Stern-Volmer plot. The limits of detection and quantification for QM-Fe3+ were calculated as 0.236 and 0.787 µM, respectively, and those for QM-Cu2+ were 0.39 and 1.31 µM, respectively. Therefore, sensor QM can be used to quantify Fe3+ and Cu2+ ions in real samples with good recovery.

DNA nanoflowers encapsulating horseradish peroxidase as a signal amplification tag for rapid diagnosis in cytology specimens

Rapid analysis of cytology samples obtained by minimally invasive sampling is essential in clinical diagnosis, yet existing diagnostic methods are often cumbersome and time-consuming. To rapidly detect the scanty number of cells in specimens, a multifunctional detection probe based on DNA nanoflower structure was prepared in this study, which possesses both signal output capability of fluorescence and oxidation reaction (colorimetric assay) for ultra-sensitive cancer cell detection. Firstly, DNA nanoflowers encapsulating horseradish peroxidase (HRP-DNA Nanoflowers, HDFs) were prepared by the rolling circle amplification (RCA) reaction and then hybridized with the aptamers labeled with fluorophores to construct the multivalent aptamer HDFs (Multi-Aptamer-HDFs) with fluorescence effect and efficient cancer cell targeting. The Multi-Aptamer-HDFs probe can be used to detect fresh clinical cytology specimens directly for fluorescence observation with sensitivity and specificity of 88.64%, and 84.85%, respectively. In addition, Multi-Aptamer-HDFs has peroxidase activity due to the encapsulation of HRP, which can catalyze the oxidation of substrates such as ABTS and DAB for color development. Therefore, we applied Multi-Aptamer-HDFs to one-step staining of clinical cytology cell blocks with a sensitivity of 88.41% and a specificity of 83.33%, which required fewer steps and reagents with a significantly shorter time required for immunocytochemical staining. The multifunctional probe, Multi-Aptamer-HDFs, prepared in this study is expected to be better applied in the rapid cellular analyses and one-step immunostaining, which is expected to provide a new means for rapid on-site assessment and on-site preliminary diagnosis.

A multifunctional probe based on ferrocenyl chalcone for the detection of tryptophan and ascorbic acid in solution

A multifunctional probe based on ferrocenyl chalcone (Probe M) was designed and successfully synthesized and found to recognize tryptophan (Trp) and ascorbic acid (AA) in solution simultaneously. The minimum detection limit of Probe M for Trp-and AA was 1.3188 × 10−4 mol/L and 1.1545 × 10−4 mol/L, respectively. The binding ratios of Probe M to Trp-and AA were obtained by job plot as 1:1 and 2:1, respectively. According to the Benesi-Hildebrand equation, the complexation constants of Probe M for Trp-and AA were 3.0025 × 106 L/mol and 4.6606 × 106 L/mol, respectively. The binding mechanism was also investigated by IR and NMR titration.

Self-consuming DNA nanogear retrieval exosomes for grading analysis of gliomas

Direct and accurate analysis of low concentrations of tumor-derived exosomes in complex biological samples is essential for non-invasive cancer diagnosis, but this remains challenging due to the lack of convenient and highly sensitive methods. Herein, we have proposed a novel strategy based on super spherical nucleic acids (SSNAs) combined with nicking enzyme triggering signal amplification for the direct detection of exosomes derived from gliomas. SSNAs utilize AuNPs as carriers, loaded with multifunctional DNA probes. And exosomes are simultaneously labeled by two aptamers. When SSNAs accurately recognize the labeled exosomes, the two make relative gear movement. During the gear movement, the probes act as an exosome-specific retrieval on the one hand, and serves as a fuel that is continuously consumed by the exosomes on the other hand, thus outputting a high-gain fluorescent signal. This strategy exhibits excellent specificity and ultra-high sensitivity for the detection of target exosomes as low as 20 particles/μL. The practicability of this method is further verified by the detection of clinical samples, which retains potential for early glioma diagnosis and grading analysis.

Two multifunctional coordination polymers based on 1,4-bis(imidazole-1-ylmethyl) benzene: Synthesis, crystal structure and sensitive detection of enrofloxacin and ciprofloxacin

In this paper, we have successfully obtained two novel compounds, namely, the Cd-based compound [Cd0.5L0.5(BA)(H2O)] n1 (L = 1,4-bis(imidazole-1-ylmethyl) benzene; BA = benzoic acid) and the Co-based compound [Co1.5L1.5(OX)1.5] n2 (H2OX = Oxalic acid) by using the hydrothermal methods. The Cd ion in 1 and the Co ion in 2 have the same coordination number. However, due to the different second ligands, namely benzoic acid in 1 and oxalic acid in 2, 1 is the 1D chain structure and 2 is the 2D layer structure, thus the second ligand also plays an important role in the structure of compound. Two CPs can be used as multifunctional luminescent probes to detect the enrofloxacin and ciprofloxacin with high selectivity and sensitivity.

Two Birds with one Stone: Dual-mode immunoassay constructed using a novel emitter ethylene glycol-induced perylene diimide and a multifunctional ANS probe

Perylene diimide (PDI) is a readily reducible electron-deficient dye that exhibits strong photoluminescent properties, providing new opportunities for synthesizing novel electrochemiluminescence (ECL) emitters. In this study, ethylene glycol (EG) was used to induce the self-assembly of PDI supramolecules for the preparation of ultrathin EG-PDI nanosheets characterized by low crystallinity and weak stacking interaction. Notably, EG-PDI integrates luminescent and catalytic functions into one device, accelerating the interfacial electron transfer and the faster charge transfer kinetics of EG-PDI with K2S2O8. Furthermore, the narrow band gap of EG-PDI facilitates its excitation at an ultra-low potential (−0.3 V). To improve the efficiency of tumor marker analysis, multifunctional Au nanostars (ANS) was introduced both as an energy acceptor of the ECL system and a probe for the photothermal system. Dual-mode immunoassay have demonstrated superior analytical performance in detecting alpha-fetoprotein (AFP), meeting the requirements of modern clinical diagnostics in resource-limited environments.

Seeded‐Growth of PCN‐224 onto Plasmonic Nanoparticles: Photoactive Microporous Nanocarriers

This study addresses the fabrication of microporous plasmonic nanocomposites (NCs) by using plasmonic nanoparticles (i.e., gold bipyramids, AuB) as seeds to grow microporous shells, specifically, metal–organic frameworks (MOF) PCN‐224 of increasing thickness from 69 to 138 nm. This method is based on using a previously synthesized Zr6‐oxo cluster and unfolds at room temperature. Notably, it is demonstrated that the concentration of the AuB seeds determines both the yield of NCs and the resultant thickness of the PCN‐224 shell, illustrating the seeded growth mechanism. Furthermore, it is found that the thermoplasmonic response of the NCs is dominated by the thickness of the microporous shell, with thicker shells having enhanced thermal confinement properties than thinner ones. As a proof of concept, the NCs are loaded with cresyl violet (CV), a lysosomal fluorescent marker. This serves to demonstrate the thermoplasmonic‐induced intracellular release of CV by the photostimulation of the AuB's plasmonic near‐infrared (NIR) band. Moreover, the NCs display exceptional efficacy as photodynamic agents when photostimulated at the PCN‐224's Soret band. In summary, this study offers a facile, efficient, and reproducible methodology for the fabrication of NCs with a controlled geometry while unlocking new possibilities in the field of nanoMOFs as multifunctional theranostic probes.

HDAC6-Activatable Multifunctional Near-Infrared Probe for Glioma Cell Detection and Elimination.

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor associated with limited treatment options and high drug resistance, presenting significant challenges in the pursuit of effective treatment strategies. Epigenetic modifications have emerged as promising diagnostic biomarkers and therapeutic targets for GBM. For instance, histone deacetylase 6 (HDAC6) has been identified as a potential pharmacological target for GBM. Furthermore, the overexpression of monoamine oxidase A (MAO A) in glioma has been linked to tumor progression, making it an attractive target for therapy. In this study, we successfully engineered HDAC-MB, an activatable multifunctional small-molecule probe with the goal of efficiently detecting and killing glioma cells. HDAC-MB can be selectively activated by HDAC6, leading to the "turn on" of near-infrared fluorescence and effective inhibition of MAO A, along with potent photodynamic therapy (PDT) effects. Consequently, HDAC-MB not only enables the imaging of HDAC6 in live glioma cells but also exhibits the synergistic effect of MAO A inhibition and PDT, effectively inhibiting glioma invasion and inducing cellular apoptosis. The distinctive combination of features displayed by HDAC-MB positions it as a versatile and highly effective tool for the accurate diagnosis and treatment of glioma cells. This opens up opportunities to enhance therapy outcomes and explore future applications in glioma theranostics.

Calibration of scanning probe microscopes: static and dynamic measures

Modern scanning probe microscopes using piezoceramic stage for scanning are becoming increasingly important metrological equipment. However, this piezoceramic stage has their shortcomings such as creep, non-linearity and hysteresis. To eliminate movement errors it is necessary to additionally calibrate the microscope using various measures. Goals: Develop the method to ensure the accuracy of calibration of a scanning probe microscope, taking into account the piezoceramics non-linearity, creep and hysteresis, using static and dynamic measures: calibration lattices and the nanometre standard. The analysis of piezoceramic stages during scanning was carried out. Considered two measures different principle of operation – static and dynamic. Calibration methods for each measure are given. The possibilities for the application of measures are demonstrated using FemtoScan multifunctional scanning probe microscope. Proposed calibration measures and methods help to improve the metrological standard of scanning probe microscopes in a wide range of movements, what allows for more accurate measurements and images of nanometre-scale objects.

A Novel Multi-Functional Fluorescence Probe for the Detection of Al3+/Zn2+/Cd2+ and its Practical Applications.

A novel multi-functional fluorescence probe HMIC based on hydrazide Schiff base has been successfully synthesized and characterized. It can distinguish Al3+/Zn2+/Cd2+ in ethanol, in which fluorescence emission with different colors (blue for Al3+, orange for Zn2+, and green for Cd2+) were presented. The limits of detection of HMIC towards three ions were calculated from the titration curve as 7.70 × 10- 9 M, 4.64 × 10- 9 M, and 1.35 × 10- 8 M, respectively. The structures of HMIC and its complexes were investigated using UV-Vis spectra, Job's plot, infrared spectra, mass spectrometry, 1H-NMR and DFT calculations. Practical application studies have also demonstrated that HMIC can be applied to real samples with a low impact of potential interferents. Cytotoxicity and cellular imaging assays have shown that HMIC has good cellular permeability and potential antitumor effects. Interestingly, HMIC can image Al3+, Zn2+ and Cd2+ in the cells with different fluorescence signals.

Carbon dots as multifunctional fluorescent probe for Fe3+ sensing in ubiquitous water environments and living cells as well as lysine detection via “on-off-on” mechanism

Iron and amino acids are essential nutrients for living organisms, and their deficiency or excess can cause a range of diseases. Therefore, there is considerable interest in developing sensing assays capable of detecting these nutrients with sensitivity, selectivity, and multifunctionality even in complex environments. In this report, hydrothermally synthesized blue fluorescent carbon dots (C-dots) from zinc gluconate were utilized for the detection of Fe3+ and lysine via “on-off” and “on-off-on” mechanisms, respectively. Specifically, the Fe3+ sensing assay achieved a broad linear range of 0–200 μM and a low limit of detection (LOD) of 1.9 μM. It is worth mentioning that the assay was also well adapted to natural aqueous environments (e.g., lake water), and its linear detection range could be extended to 0–1000 μM with a LOD of 3.3 μM. Furthermore, the assay was also effective for intracellular Fe3+ tracking. Most importantly, the assay could also be applied for the quantitative detection of lysine with a linear range of 0–1200 μM and LOD of 8.6 μM. Systematic mechanistic studies revealed that Fe3+ sensing was based on a static quenching process between C-dots and Fe3+, whereas a stronger complexation might have formed between Fe3+ and Lys, leading to the release of C-dots and thus the recovery of fluorescence.

Eu3+-Doped aluminum Metal-Organic Frameworks: A versatile platform for ratiometric detection of histidine and Water, and visible fingerprint identification

Ratiometric fluorescent sensors possess inherent self-calibration features that enable the mitigation of interference from factors unrelated to the analysis. This characteristic results in heightened sensitivity and more pronounced visual detection during qualitative and quantitative analytical processes. A ratiometric fluorescence probe Eu/Al-MOF has been successfully prepared via Eu3+ doped aluminum metal − organic frameworks. Upon introducing histidine, the fluorescence intensity of Eu3+ showed a noteworthy increase, whereas the intensity originating from the ligand decreased owing to enhancing energy transfer from the ligand to Eu3+ ions in the probe. Eu/Al-MOF could detect histidine over a wider linear range of 0.1–400 μM and a lower detection limit of 0.04 μM. Besides, in the presence of water in organic solvents, the excited state of Eu3+ in the probe could be coupled with the O-H oscillation of water molecules, and the excited state energy from Eu3+ would be transferred to the water molecules so that only the fluorescence intensity of Eu3+ gradually decreased. Thus, the proportional detection of trace water could be realized. In ethanol and DMF, the detection range for water was 0.1–20 % and 0.5–20 %, respectively. Moreover, it was found that Eu/Al-MOF could efficiently achieve the visualization identification of fingerprints, providing the possibilities for applying the nano-sensor as a promising multifunctional fluorescence probe.

Designing a multifunctional AIE active fluorescent Schiff base probe: Sensitive heavy metal ions recognition and water induced aggregation

A new multifunctional Schiff base probe AnQn containing dual fluorophore (anthracene-quinoline) has been synthesised via a facile one-pot reaction. This probe demonstrated the ability to selectively discriminate group IIIA metal...

Development of wafer-scale multifunctional nanophotonic neural probes for brain activity mapping.

Optical techniques, such as optogenetic stimulation and functional fluorescence imaging, have been revolutionary for neuroscience by enabling neural circuit analysis with cell-type specificity. To probe deep brain regions, implantable light sources are crucial. Silicon photonics, commonly used for data communications, shows great promise in creating implantable devices with complex optical systems in a compact form factor compatible with high volume manufacturing practices. This article reviews recent developments of wafer-scale multifunctional nanophotonic neural probes. The probes can be realized on 200 or 300 mm wafers in commercial foundries and integrate light emitters for photostimulation, microelectrodes for electrophysiological recording, and microfluidic channels for chemical delivery and sampling. By integrating active optical devices to the probes, denser emitter arrays, enhanced on-chip biosensing, and increased ease of use may be realized. Silicon photonics technology makes possible highly versatile implantable neural probes that can transform neuroscience experiments.

Developing NIR xanthene-chalcone fluorophores with large Stokes shifts for fluorescence imaging.

A series of novel near-infrared (NIR) xanthene-chalcone fluorophores were constructed through a modular synthesis with the electron-donating xanthene moiety and the electron-withdrawing chalcone moiety. These fluorophores are convenient for fluorescence imaging in living cells, benefiting from their NIR emissions (650-710 nm), large Stokes shifts (>100 nm), moderate quantum yields and low cytotoxicity. The substituted hydroxyl group of the xanthene-chalcone fluorophore HCA-E facilitates the development of multifunctional fluorescent probes. As an example, a highly sensitive and selective probe N-HCA-E for glutathione (GSH) detection was developed based on the fluorophore HCA-E. A 4-nitrobenzenesulfonyl (4-Ns) group was introduced to cage the hydroxyl group of HCA-E, which was used as a selective recognition site for the thiol of GSH and an effective fluorescence quencher. Probe N-HCA-E revealed NIR "turn-on" fluorescence (709 nm) for endogenous and exogenous GSH detection in lysosomes with a large Stokes shift (129 nm) and high anti-interference ability.

AI-driven precision subcellular navigation with fluorescent probes.

Precise navigation within intricate biological systems is pivotal for comprehending cellular functions and diagnosing diseases. Fluorescent molecular probes, designed to target specific biological molecules, are indispensable tools for this endeavor. This paper delves into the revolutionary potential of artificial intelligence (AI) in crafting highly precise and effective fluorescent probes. We will discuss how AI can be employed to: design new subcellular dyes by optimizing physicochemical properties; design prospective subcellular targeting probes based on specific receptors; quantitatively explore the potential chemical laws of fluorescent molecules to optimize the optical properties of fluorescent probes; optimize the comprehensive properties of the probe and guide the construction of multifunctional targeting probes. Additionally, we showcase recent AI-driven advancements in probe development and their successful biomedical applications, while addressing challenges and outlining future directions towards transforming subcellular research, diagnostics, and drug discovery.