Simple Probe Research Articles

Ultrasensitive fluorescence detection of antitumor drug methotrexate based on a terbium-doped silica dendritic probe.

A novel strategy was developed for the detection of methotrexate (MTX) via the quenching effect of MTX on the fluorescence intensity of terbium-doped dendritic silica particles (Tb@KCC-1). The fluorescence intensity of Tb@KCC-1 can be effectively quenched by MTX at 546 nm under an excitation wavelength of 233 nm. The quenched fluorescence is proportional to the amount of MTX in both plasma and exhaled breath condensate (EBC) samples. Under the optimal conditions, the linear dynamic ranges of the developed method were 44 nM to 2.2 μM for EBC, 44 nM to 0.22 μM and 0.22-2.2 μM for plasma samples. The limit of detection (LOD) and limit of quantification (LOQ) in both plasma and EBC media are 35 and 116 nM, respectively. The developed method has the benefits of fast analysis time, simple approach, high specificity, and sensitivity for the detection of MTX in both media. This nanoprobe has been successfully utilized for the quantification of MTX in patients' plasma and spiked EBC samples, proving the applicability of the nanoprobe for MTX detection in real samples.

Design, synthesis and cell imaging of a simple peptide-based probe for the selective detection of RNA.

Here we present a novel peptide-based fluorescent "turn-on" molecule P1 for detecting RNA, in a double or single strand, AU-rich or CG-rich. Both computational and experimental studies indicate that the detection efficiency depends on the binding affinity of P1 and conformational changes. P1 could be applied for cell imaging without any additional transfection vectors. Selective detection of RNA in cells was determined by RNase digestion. Successful application of P1 for RNA imaging in cell mitosis reveals that it may have broad applications in research, biotechnology and medical science.

Development of a Simple and Low-Cost Prototype Probe Fully-Compatible with ASAP Source for the Analysis of Human Breath in Real-Time

Development of a Simple and Low-Cost Prototype Probe Fully-Compatible with ASAP Source for the Analysis of Human Breath in Real-Time

Polymer surface ligand and silica coating induced highly stable perovskite nanocrystals with enhanced aqueous fluorescence for efficient Hg2+ and glutathione detection.

The poor stability and aqueous-quenching of fluorescence of perovskite nanocrystals (NCs) hinder their application in bio-detection and bio-imaging. Herein, through the synergistic effects of polymer surface ligand and silica encapsulation, highly stable and enhanced aqueous fluorescent CsPbBr3-mPEG@SiO2 NCs were synthesized and used as a novel "on-off-on" fluorescent probe for highly sensitive and selective detection of mercury ions (Hg2+) and glutathione (GSH) in aqueous solutions. The effects of the methoxypolyethylene glycol amine (mPEG-NH2) ligand and silica encapsulation on the stability and aqueous fluorescence of the CsPbBr3 NCs were studied. It indicated that the aqueous fluorescence of perovskite NCs was increased by 2.59 times. The water stability was also greatly improved, with the NCs maintaining 73% of their original fluorescence after storage for 30 days in water. X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyses further demonstrated that the NCs were successfully passivated by mPEG-NH2 and silica. The fluorescence of the CsPbBr3-mPEG@SiO2 nanocrystals was effectively quenched by Hg2+ which is attributed to the electron transfer process between NCs and Hg2+. Then, through the interaction between Hg2+ and GSH, the restoration of fluorescence for CsPbBr3-mPEG@SiO2 was realized. The "on-off-on" fluorescent probe can be used for the detection of Hg2+ and GSH with a low detection limit of 0.08 nM and 0.19 μM, respectively. It also shows a fast response time and high accuracy for practical sample detection. The simple and sensitive fluorescent probe of CsPbBr3-mPEG@SiO2 shows great potential in environmental and biological sensing.

A fluorescence nanoprobe for detecting the effect of different oxygen and nutrient conditions on breast cancer cells' migration and invasion.

Cancer cell migration and invasion are initial steps for tumor metastasis, which increases patient mortality. The tumor microenvironment is characterized as being hypoxic and nutrient deficient. Previous studies have suggested that hypoxia induces tumor metastasis, while the low nutrient content is not beneficial for tumor metastasis. Thus, it is necessary to develop a simple probe to study the changes in cancer migration and invasion. Herein, we designed a nanoprobe based on gold nanoparticles (Au NPs) to monitor the effect of different oxygen and nutrient conditions on the migration and invasion of breast cancer cells through detecting the changes in levels of RAB-22a and MMP-2 mRNA in living cells. After incubating MCF-7 and MDA-MB-231 cells with different concentrations of oxygen and nutrients, fluorescence imaging assays were used to evaluate migration and invasion. This work provides a new insight in the effect of different tumor microenvironments on cell migration and invasion.

Catalytic C–H Oxidation Enhances Polyethylene Bonding

Selectively adding functionality to commodity plastics is an abiding challenge in polymer science. In this issue of Chem, Hartwig and co-workers describe a selective, catalytic oxidation of polyethylene C–H bonds by using high-valent ruthenium-oxo species. The transformation increases polyethylene’s adhesive properties without significantly modifying its thermal stability or mechanical strength.

A Simple Aggregation-Induced Emission Nanoprobe with Deep Tumor Penetration for Hypoxia Detection and Imaging-Guided Surgery in Vivo

The pan-cancer detection and precise visualization of tiny tumors in surgery still face great challenges. As tumors grow aggressively, hypoxia is a common feature of solid tumors and has supplied a general way for detecting tumors. Herein, we report a simple aggregation-induced emission nanoprobe-TPE-4NE-O that can specifically switch on their fluorescence in the presence of cytochrome P450 reductase, a reductase which is overexpressed under hypoxia conditions. The probe can selectively light up the hypoxia cells and has shown enhanced deep tumor penetration via charge conversion both in vitro and in vivo. After being modified with FA-DSPE-PEG, higher tumor uptake can be seen and FA-DSPE/TPE-4NE-O showed specific visualization to the hypoxia cancer cells. Excitingly, much brighter fluorescence was accumulated at the tumors in the FA-DSPE/TPE-4NE-O group, even though the tumor was as small as 2.66 mm. The excellent performance of FA-DSPE/TPE-4NE-O in detecting tiny tumors has made it possible for imaging-guided tumor resection. More importantly, the probe exhibited good biocompatibility with negligible organ damage and eliminated a hemolysis risk. The simple but promising probe has supplied a new strategy for pan-cancer detection and tiny tumor visualization, which have shown great potential in clinical translation.

A review on simple and highly sensitive plastic optical fiber probes for bio-chemical sensing

Abstract A review on bio-chemical label-free sensing applications based on receptors combined with multimode plastic optical fibers (POFs) is carried out. In particular, this work focuses on different kinds of POF intrinsic sensors used in transmission mode, exploiting various types of receptors and useful in several application fields. The sensor structures and the sensing mechanisms of different simple, highly sensitive, and low-cost POF probes are reported and compared. Moreover, different kinds of chemical and biological receptors combined with POF probes, highlighting the advantages and disadvantages of each receptor, are presented in detail. More specifically, the chosen POF sensing platforms, including low-cost and simple interrogation setups, are described showing their ability to monitor specific receptors exploiting intensity variation techniques and plasmonic phenomena, as well. Finally, a prospect of future developments of biochemical sensors with multimode POFs is discussed.

Development of Second Generation Activity-Based Chemical Probes for Sirtuins.

NAD+ (nicotinamide adenine dinucleotide)-dependent protein deacylases, namely, the sirtuins, are important cell adaptor proteins that alter cell physiology in response to low calorie conditions. They are thought to mediate the beneficial effects of calorie restriction to extend longevity and improve health profiles. Novel chemical probes are highly desired for a better understanding of sirtuin’s roles in various biological processes. We developed a group of remarkably simple activity-based chemical probes for the investigation of active sirtuin content in complex native proteomes. These probes harbor a thioacyllysine warhead, a diazirine photoaffinity tag, as well as a terminal alkyne bioorthogonal functional group. Compared to their benzophenone-containing counterparts, these new probes demonstrated improved labeling efficiency and sensitivity, shortened irradiation time, and reduced background signal. They were applied to the labeling of individual recombinant proteins, protein mixtures, and whole cell lysate. These cell permeable small molecule probes also enabled the cellular imaging of sirtuin activity change. Taken together, our study provides new chemical biology tools and future drug discovery strategies for perturbing the activity of different sirtuin isoforms.

Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications.

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 μM, with a detection limit (LOD) of 0.115 μM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

A simple sensitive ratiometric fluorescent probe for the detection of mercury ions in living cells and zebrafish

Mercury, as a highly toxic heavy metal, can cause very serious harm to human health and even death in severe cases. Therefore, we synthesized a novel ratiometric fluorescent probe for detecting mercury ions, with mercaptoethanol as the recognition receptor. Probe CMER could determine mercury ions in 0–1.6 μM and the detection limit is 7.6 nM. Moreover, CMER manifested a fast response for Hg2+ (within 5 s) and simultaneously observed that the color changed from light yellow to orange by naked eye. In addition to these preeminent spectral properties, the probe also had satisfactory bioimaging results in RAW 264.7 macrophage cells and zebrafish.

Enhanced photocatalytic and electrochemical properties of Cu doped NiMnFe2O4 nanoparticles synthesized via probe sonication method

A series of copper (X) doped NiMnFe2O4 (X = 0.1, 0.2, 0.3, 0.4) nanoparticles (NPs) were synthesized using a simple and effective probe sonication method. The obtained NPs were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–visible studies. The photocatalytic degradation activity of Ni0.2CuxMn0.2Fe2O4 (x = 0.1, 0.2, 0.3, 0.4) NPs were evaluated by degrading methylene blue (MB) and Drimarene yellow (DY) dyes under UV light. The removal efficiencies of 70.2% and 43.3% by NPs with X = 0.1 was observed for MB and DY, respectively. While NPs with X = 0.4 displayed removal efficiencies of 98.1% for MB and 28.9% for DY. The effect of dopant concentration and pH on the photocatalytic ability of the NPs was studied in detail. Electrochemical measurements were performed for the NPs using Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) using a carbon paste electrode in acidic (0.1 M HCl) and alkaline (0.1 M NaOH) electrolytes. The specific capacitance values for electrodes with X = 0.1 and 0.4 M were calculated as 244.5 and 498.6 F g−1 in 0.1 M HCl; 40.14 and 25.01 F g−1 in 0.1 M NaOH at a scan rate of 10 mV/s, respectively. EIS measurements further confirmed the CV results. The impedance spectrum of electrode with X = 0.4 in 0.1 M HCl displayed a lowered arc with a smaller diameter in the region of high frequency, revealing the low charge transfer resistance (RCt = 5.281 Ω) and high capacitance (C = 1.654 × 10−8 F) of the electrode. The high reversibility of electrodes and remarkable photocatalytic activity makes them favourable for applications in multifunctional fields.

A Simple Colorimetric Probe for Sensitive Detection of Hg2+ Based on MnO2 Nanosheets and Monothioglycerol

AbstractIt is of great significance to develop efficient platforms for the detection of hypertoxic Hg2+. Colorimetric probes have received much attention for the detection of Hg2+ in the last decades. In this work, a colorimetric probe composed of MnO2 nanosheets and monothioglycerol (MTG) was rationally designed for Hg2+ detection, which was facially prepared via one‐step reaction at room temperature. The formation of Hg−S bond between Hg2+ and MTG inhibited the decomposition ability of MTG toward MnO2 nanosheets, thus resulting in a color change from colorless to brown. On this basis, the probe quantified Hg2+ in the concentration range from 2 to 60 μM with a low detection limit of 0.75 μM. The probe was applied to the detection of Hg2+ in tap water successfully, and was further fabricated into test strips for the convenience of use. Thereby, a simple and sensitive colorimetric probe for Hg2+ is developed in this work, which holds future promise for monitoring Hg2+ in the environment.

A novel ultrasensitive peroxynitrite-specific fluorescent probe and its bioimaging applications in living systems

Peroxynitrite, one of the well-known reactive nitrogen species (RNS), which is considered to be an important oxidant. Besides, peroxynitrite plays an important role in the broad spectrum of biological processes, and it is also a vital participant in the emergence of cancer. To this end, the fluorescent probe PN-1 was rationally synthesized, which contains a coumarin-fused coumarin dye and borates as the specific recognition group. Probe PN-1 exhibits several obvious performances, for instance, high specificity, excellent sensitivity, and it could promptly respond toward ONOO−. Using this simple fluorescent probe, we achieved the imaging of endogenous and exogenous ONOO− fluctuations in living cells and zebrafish. Moreover, PN-1 has efficiently differentiated cancerous cells from normal cells owing to image their different native ONOO− levels, these results indicated that PN-1 is expected to be an analytical tool, for researching ONOO− related cancer biology and studying the related effect of ONOO− in food.

Highly sensitive and rapid detection of thiabendazole residues in oranges based on a luminescent Tb3+-functionalized MOF

Thiabendazole (TBZ), has been extensively employed as a pesticide and/or a fungicide in agriculture, while its residues would threaten to public health and safety. Simple, rapid and sensitive probes for detection of TBZ in real food samples is significantly desirable. In present work, a highly selective and sensitive luminescent sensor for monitoring TBZ in oranges has been constructed based on a Tb3+-functionalized Zr-MOF (Tb3+@1). Tb3+@1 exhibited many attractive sensing properties toward TBZ, including broad linear range (0–80 μM), high selectivity, low LOD (0.271 μM) and rapid response time (less than1 min). Moreover, the probe was employed to determine TBZ in real orange samples, in which good recoveries from 98.41 to 104.48% were obtained. It only takes 35 min for the whole process of detection TBZ in real orange samples combined with QuEChERS method. Therefore, this work provided a reliable and rapid method for monitoring the TBZ in real orange samples.

A highly selective and simple fluorescent probe for salbutamol detection based on thioglycolic acid-capped CdTe quantum dots.

In this paper, a highly fluorescent water-soluble CdTe quantum dots (CdTe QDs) stabilized with thioglycolic acid (TGA) were synthesized for the quantitative and selective determination of salbutamol (SAL). When ten different of 2.09×10-6 mol L-1 alpha-2 adrenoceptor agonist were added to 4.38×10-4 mol L-1CdTe QDs solution, the fluorescence signal of the CdTe QDs quenched obviously by SAL with 57.32% and 0.815% - 7.00% for other nine kinds of veterinary medicine, such as tulobuterol, fenoterol, phenylethanamine A, simatero, penbutolol, clenbuterol, ractopamine, terbutaline and clorprenaline. The result shows that the CdTe QDs is highly sensitive sensor for SAL. The quenching mechanism has been investigated by absorption spectroscopy and KSV at different temperatures, and shew a static quenching process than dynamic quenching. Under the optimal conditions, respectively the straight line equation (F0/F=0.1491×106 C+1.3078) was found between the relative fluorescence intensity and the concentration of SAL was in the range of 6.27×10-8 to 2.09×10-7 mol L-1, and the limit of detection was 4.2×10-8 mol L-1. The proposed method has been applied to the determination of SAL in pig urine samples.

Multi-responsive fluorescent probe based on AIE for the determination of Fe3+, total inorganic iron, and CN- in aqueous medium and its application in logic gates

A novel and simple probe (denoted LN-1) with AIE property based on malononitrile and 4-diethylaminobenzaldehyde was designed and synthesized. The use of two different mechanisms for the independent detection of Fe3+ and CN− is more convenient and efficient than the continuous detection of anions and cations. The detection mechanism was verified by mass spectrometry (MS), nuclear magnetic resonance (NMR) spectrum, and particle size distribution. Under optimized experimental conditions, excellent calibration curves were obtained for the LN-1-Fe3+ and the LN-1-CN− with detection limits of 0.17 and 0.39 μM, respectively. This method was successfully applied to detect the content of Fe3+ and total inorganic iron in actual samples. Owing to its low cytotoxicity, good biocompatibility, and enhanced orange emission in aqueous solution, the LN-1 was successfully applied for CN− imaging in live cells. In addition, Fe3+ and EDTA incorporation into the LN-1 changed the fluorescent intensity, which is beneficial in constructing ultrasensitive INHIBIT logic gate.

Role of USG in thyroid diseases

Thyroid gland is a very unique gland in the body. It is the only gland in the body which depends on the outside source for iodine directly. It has a very rich blood supply which can be compared with that of the kidneys and also, it’s the only gland in the body which has the capacity to produce, store and exclude its products when the body needs the products. So, its regulation is remarkable. Its very superficially placed and can be easily studies using high frequency probes. There have been studies where a simple trans vaginal probe has been successfully used to study the gland. The main reason being that its very superficially placed and thus high frequency probes can be used successfully to study such structures accurately. This study puts in an effort to study the role of USG in thyroid diseases.

Infrastructure-Less Vehicle Traffic Density Estimation via Distributed Packet Probing in V2V Network

In this paper, we address the problem of vehicle traffic density estimation without relying on infrastructure cameras or sensors on the road. Previous infrastructure-less approaches still require some prior knowledge on the road infrastructure, e.g., via road topology map. We seek a lightweight estimation method based only on vehicle-to-vehicle (V2V) communication, i.e., without using any prior knowledge. The main objective of this paper is to examine traffic density through simple yet efficient packet probing within a survey time period and obtain a snapshot of the traffic density distribution map. We propose an on-demand vehicle sampling algorithm that makes a probing packet at a vehicle (i.e., sampler) keep sampling to explore the local traffic density on a cell basis. If a current sampler does not operate as an efficient carrier, the packet selects another one as the next sampler via inner-relaying and outer-relaying procedures. To effectively adapt the level of granularity of traffic density depending on the remaining survey time, we present an adaptive cell sizing algorithm. Further, we extend the sampling activity to multiple vehicle samplers by making them aggregate their collected information and also negotiate their future areas to explore. Within a designated deadline, multiple samplers collaborate for more accurate and fast traffic density estimation. By doing so by iterations till the given survey deadline, we can gather a complete view of traffic density estimates based on multiple sources where some areas have more detailed information, whereas others do less. Experiments with a real trace-driven simulation demonstrate that our proposed algorithm effectively estimates the distribution of traffic density considering local traffic conditions compared to other counterpart algorithms, with a factor of up to 9.5.

An acoustic impedance probe for the teaching of musical acoustics to non-majors

Physics of Music or similar titles are found in the course catalogues of many colleges and universities. Almost always such courses are directed at non-physics majors and even non-science majors. As a result the course materials must be presented without reliance on advanced mathematical concepts, and thus a great deal of in-class demonstrations combined with video clips are used instead. For example, the concept of acoustic impedance, when introduced rigorously, requires the use of complex algebra. However, a discussion on a qualitative level can be done in a way that is accessible to undergraduate students without a great deal of math background. In order to introduce some measure of quantitative discussion, we are using a simple home-built impedance probe to record the input impedances of simple air columns as well as real instruments. In this talk we will discuss the details of the impedance transducer and show how it can be used to demonstrate how a flared bell changes the resonances of cylindrical air columns, the effect of differently shaped mouth pieces on the acoustic properties of a brass instrument, and a number of other characteristics of musical instruments.