Conventional Organic Dyes Research Articles

Early Detection and Noninvasive Staging of Kidney Dysfunction by a PEGylated Conventional Fluorophore via GFR-Sensitive Renal Transport.

Noninvasive fluorescence imaging of renal function is a valuable technique for understanding kidney disease progression and the development of renal medicine. This technique requires sensitive imaging probes for reporting renal dysfunction accurately at early stage. Herein, a molecularly engineered imaging probe (800CW-PEG45-COOH) was synthesized by simply PEGylating conventional near-infrared fluorophore IRDye800CW with NH2-PEG45-COOH (molecular weight ∼2100 Da) for early detection and staging of renal dysfunction through noninvasive real-time kidney imaging. 800CW-PEG45-COOH not only cleared through the kidney efficiently (>90% injection dosage at 24 h postinjection) but was also found to be freely filtered by glomeruli without renal tubular reabsorption and secretion. Despite this simple construction strategy, the transport of 800CW-PEG45-COOH within the kidneys was extremely sensitive to the alteration of the glomerular filtration rate (GFR), which enabled it to detect renal dysfunction much earlier than commonly used serum biomarkers and stage kidney function impairments (mild vs severe dysfunction) via imaging-based kidney clearance kinetics. This work not only provides a promising optical imaging probe for the noninvasive evaluation of kidney function but also highlights the utility of PEGylation in enhancing the performance of conventional organic dyes in biomedical applications.

Poly(dopamine) coated H-aggregates of amphoteric charged near-infrared absorbing cyanine dyes for enhanced photothermal tumor imaging and therapy

Cancer and tumors pose a formidable danger to health, with clinical treatments often beset by adversities such as deleterious side effects, suboptimal therapeutic outcomes, and the propensity for subsequent recurrence and metastasis. In this work, we present a self-assembled organic dyes as an innovative approach for the photothermal imaging and therapy for tumors. Cyanine aggregation nanoparticles (Cy-aggregate) were prepared by autonomous aggregation of amphoteric charged cyanine dyes in the near-infrared spectral range, and after the formation of aggregates, a new absorption peak of H-aggregates appeared around 808 nm, which were subsequently modified with dopamine to obtain cyanine aggregate@PDA nanoparticles (Cy-aggregate@PDA). The nanoparticle exhibits distinctive electrostatic gravitation-mediated H-type aggregation, resulting in the quenching of near-infrared fluorescence. Upon exposure to 808 nm laser irradiation, the self-aggregated cyanine dyes do not emit the absorbed energy through fluorescence as conventional organic dyes do, but efficiently converts the energy into heat, with a photothermal conversion efficiency of up to 51.4%, which can facilitate photothermal therapy and imaging. The inclusion of poly(dopamine) engenders heightened photothermal conversion efficiency, improved stability, and diminished cytotoxicity within the nanoparticles. Moreover, the nanoparticles manifest remarkable dispersion, biocompatibility, and stable photothermal properties, thus bestowing upon them a novel avenue for the photothermal treatment of tumors.

Luminescent carbon dots versus quantum dots and gold nanoclusters as sensors.

Ultra-small nanoparticles, including quantum dots, gold nanoclusters (AuNCs) and carbon dots (CDs), have emerged as a promising class of fluorescent material because of their molecular-like properties and widespread applications in sensing and imaging. However, the fluorescence properties of ultra-small gold nanoparticles (i.e., AuNCs) and CDs are more complicated and well distinguished from conventional quantum dots or organic dye molecules. At this frontier, we highlight recent developments in the fundamental understanding of the fluorescence emission mechanism of these ultra-small nanoparticles. Moreover, this review carefully analyses the underlying principles of ultra-small nanoparticle sensors. We expect that this information on ultra-small nanoparticles will fuel research aimed at achieving precise control over their fluorescence properties and the broadening of their applications.

(Invited) Highly Emissive CdTe Quantum Dots Passivated with Novel Branched Ligands as Fluorescent Sensors

Fluorescent-based sensors attract enormous attention due to their facile nature, simplicity, superior selectivity and sensitivity, and better reproducibility and reliability. The sensing parameters, such as detection limit, dynamic range, and the possibility for multiplexed detection, rely hugely on the physicochemical properties of the fluorophore used. Therefore, the choice and rational design of fluorescent probes demand considerable attention. The growing interest in highly fluorescent semiconductor quantum dots as sensors or imaging probes is evident from the numerous reports available in the literature. Unlike conventional organic dyes, novel fluorescent quantum dots-inorganic nanocrystals have manifold advantages. QDs have symmetric and narrow emission profiles, high absorption efficiency in the UV region, high quantum yields, especially in the NIR region, exorbitant photo and temporal stability, and shallow photo-bleaching effect. The optical properties of QDs are primarily defined by the nature of constituent materials, size and shape, surface chemistry, and the nature of dangling bonds. The applicability of CdTe QDs was limited in the biological realm mainly due to the highly toxic nature of its constituent materials. The use of benign ligands is one procedure to be adopted to overcome this impediment. Also, the stability of the QDs warrants the limited bleaching of the material. The aqueous solubility of the material is another requirement to be satisfied. The functional groups in ligands also play a significant role in determining the stability of QDs and the utility of the QDs synthesized, as it can advocate the possibility of reactions and recognition of suitable analytes in sensing schemes. This talk will discuss the choice of organic ligands with side methyl chains that can supplement or be used in alternatives to the existing ligands for synthesizing QDs. We have employed easy and facile colloidal synthetic procedures for an extended period for manipulating the size of QDs formed, which can be further implemented for the sensing of various analytes. The side methyl chain added several benefits for the QDs synthesis, such as providing better stability of the QDs and in the sensing scenario.

Effect of band gap and particle size on photocatalytic degradation of NiSnO3 nanopowder for some conventional organic dyes

The present article deals with the study of degradation of organic dyes: congo red (CR), methylene blue (MB) and rhodamin B (RB), using nickel stannate (NiSnO3) nanopowder as photocatalyst. Nanocrystals of NiSnO3 have been synthesized by co-precipitation method. The powder X-ray diffraction (XRD) data taken at room temperature confirms the formation of crystalline phase in NiSnO3. The average particle size, estimated from transmission electron microscopy (TEM) increases from ∼5.05 to ∼8.05 nm with an increase in sintering temperature from 250 to 400 °C. The band gap of the photocatalyst measured (de-ionized water used as eluent) employing Ultraviolet–Visible (UV–Vis) spectroscopy reduces from ∼3.38 to ∼2.90 eV for an identical rise in sintering temperature. The percentage degradation is maximum (∼94%) for CR dye. Among our studied samples, NiSnO3 photocatalyst sintered at 400 °C has the lowest band gap, and the largest average particle size. This shows the best photocatalytic performance. Degradation efficiency of CR dye in various pH ranges (the optimized pH value is ∼5.0) and cyclic stability of the catalyst were also examined. CR dye degradation is ∼92.3% after fifth cycle which is very close to ∼94% degradation of first cycle.

Fluorogenic and Cell‐Permeable Rhodamine Dyes for High‐Contrast Live‐Cell Protein Labeling in Bioimaging and Biosensing

AbstractThe advancement of fluorescence microscopy techniques has opened up new opportunities for visualizing proteins and unraveling their functions in living biological systems. Small‐molecule organic dyes, which possess exceptional photophysical properties, small size, and high photostability, serve as powerful fluorescent reporters in protein imaging. However, achieving high‐contrast live‐cell labeling of target proteins with conventional organic dyes remains a considerable challenge in bioimaging and biosensing due to their inadequate cell permeability and high background signal. Over the past decade, a novel generation of fluorogenic and cell‐permeable dyes has been developed, which have substantially improved live‐cell protein labeling by fine‐tuning the reversible equilibrium between a cell‐permeable, nonfluorescent spirocyclic state (unbound) and a fluorescent zwitterion (protein‐bound) of rhodamines. In this review, we present the mechanism and design strategies of these fluorogenic and cell‐permeable rhodamines, as well as their applications in bioimaging and biosensing.

Fluorogenic and Cell-Permeable Rhodamine Dyes for High-Contrast Live-Cell Protein Labeling in Bioimaging and Biosensing.

The advancement of fluorescence microscopy techniques has opened up new opportunities for visualizing proteins and unraveling their functions in living biological systems. Small-molecule organic dyes, which possess exceptional photophysical properties, small size, and high photostability, serve as powerful fluorescent reporters in protein imaging. However, achieving high-contrast live-cell labeling of target proteins with conventional organic dyes remains a considerable challenge in bioimaging and biosensing due to their inadequate cell permeability and high background signal. Over the past decade, a novel generation of fluorogenic and cell-permeable dyes has been developed, which have substantially improved live-cell protein labeling by fine-tuning the reversible equilibrium between a cell-permeable, nonfluorescent spirocyclic state (unbound) and a fluorescent zwitterion (protein-bound) of rhodamines. In this review, we present the mechanism and design strategies of these fluorogenic and cell-permeable rhodamines, as well as their applications in bioimaging and biosensing.

Quantum dots for temperature sensing.

Quantum dots are three-dimensional nanoparticles of semiconductors with typical sizes ranging from 2 to 10 nm. Due to the quantum confinement effect the energy gap increase with the size decreasing resulting in size-depended and fine-tunable optical characteristics. Besides this, the energy structure of a quantum dot with a certain size is highly sensitive to environmental conditions. These specific properties open a wide range of applications starting from optical and optoelectronic devices and ending with biosensing and life science. Temperature is one of those parameters influencing strongly on the optical properties of semiconductor nanocrystals, which make them promising materials for temperature sensing, more often using a fluorescent response. Compared to the conventional organic dyes already applied in this field, quantum dots exhibit a set of advantages, such as high quantum yield and photostability, long fluorescence lifetime, higher Stokes shift, and ability to surface functionalization with targeted organic molecules aimed to provide them biocompatibility. In this review, we briefly discuss the properties of II-VI and assumingly less toxic I-III-VI quantum dots, mechanisms of temperature-induced fluorescence response, and the feasibility of their practical application in the field of thermal sensing.

Construction of cellulose structural-color pigments with tunable colors and iridescence/non-iridescence

Structural colorations have been recognized as a significant way to replace conventional organic dyes for paints, inks, packaging, and cosmetics because of brilliant colors, high stability, and eco-friendliness. However, most current structural-color pigments present an iridescent appearance, and it remains difficult to mitigate a trade-off between lowering the iridescence effect and maintaining the color saturation and brightness. Here, we demonstrate a universal yet economical approach to prepare cellulose structural-color pigments with different sizes. A combined ultrasonication and grinding treatment is explored to adjust the pigment colors as well as control the iridescence-to-non-iridescence transition that depends on the pigment size. The cellulose pigments can be applied on irregular and curved surfaces, having high water-, chemical-, and mechanical-resistances. With humidity-sensing behaviors, the pigments can be further integrated into monitoring systems for environmental management. Such a preparation strategy overcomes the limitation of controlling iridescent and non-iridescent structural colors without sacrificing color properties, which may bring more opportunities to develop new eco-friendly pigments for wide applications.

Quantum dots for temperature sensing

Quantum dots are three-dimensional nanoparticles of semiconductors with typical sizes ranging from 2 to 10 nm. Due to the quantum confinement effect the energy gap increase with the size decreasing resulting in size-depended and fine-tunable optical characteristics. Besides this, the energy structure of a quantum dot with a certain size is highly sensitive to environmental conditions. These specific properties open a wide range of applications starting from optical and optoelectronic devices and ending with biosensing and life science. Temperature is one of those parameters influencing strongly on the optical properties of semiconductor nanocrystals, which make them promising materials for temperature sensing, more often using a fluorescent response. Compared to the conventional organic dyes already applied in this field, quantum dots exhibit a set of advantages, such as high quantum yield and photostability, long fluorescence lifetime, higher Stokes shift, and ability to surface functionalization with targeted organic molecules aimed to provide them biocompatibility. In this review, we briefly discuss the properties of II-VI and assumingly less toxic I-III-VI quantum dots, mechanisms of temperature-induced fluorescence response, and the feasibility of their practical application in the field of thermal sensing.

Progress in Fluorescence Biosensing and Food Safety towards Point-of-Detection (PoD) System.

The detection of pathogens in food substances is of crucial concern for public health and for the safety of the natural environment. Nanomaterials, with their high sensitivity and selectivity have an edge over conventional organic dyes in fluorescent-based detection methods. Advances in microfluidic technology in biosensors have taken place to meet the user criteria of sensitive, inexpensive, user-friendly, and quick detection. In this review, we have summarized the use of fluorescence-based nanomaterials and the latest research approaches towards integrated biosensors, including microsystems containing fluorescence-based detection, various model systems with nano materials, DNA probes, and antibodies. Paper-based lateral-flow test strips and microchips as well as the most-used trapping components are also reviewed, and the possibility of their performance in portable devices evaluated. We also present a current market-available portable system which was developed for food screening and highlight the future direction for the development of fluorescence-based systems for on-site detection and stratification of common foodborne pathogens.

Multiply Twisted Chiral Macrocycles Clamped by Tethered Binaphthyls Exhibiting High Circularly Polarized Luminescence Brightness

Chiral macrocyclic dimers, trimers, and tetramers composed of paraphenylene and tethered binaphthyl were synthesized, and their molecular structures and chiroptical properties were investigated. X-ray analysis and theoretical calculations revealed that multiple twisted molecular structures - dimers, trimers, and tetramers - adopt figure-of-eight, Möbius triangle, and concave rectangle structures, respectively. These homologues have large ϵ values in their UV-vis absorption spectra because of the π-conjugation of the naphthalene-phenylene-naphthalene frameworks. Owing to the shape-persistent ring structure and tethering with -OCH2 CH2 O-, high fluorescence quantum yields and a relatively high dissymmetry factor gCPL in circularly polarized luminescence (CPL) spectra were achieved. This results in CPL brightness (BCPL ) of over 100, which is greater than that of the conventional organic CPL dye.

Cross-Linking Induced Emission of Polymer Micelles for High-Contrast Visualization Level 3 Details of Latent Fingerprints.

Rationally developing an intelligent tool for high-contrast fluorescence imaging of latent fingerprints (LFPs) is gaining much concern in many applications such as medical diagnostics and forensic investigations. Herein, the off-on fluorescent polymer micelles (PMs) have been rationally designed and synthesized for high-contrast fluorescence imaging of LFPs through the cross-linking reaction of hydrazine (N2H4) and aldehyde group of polymer. Excitingly, the cross-linking (N2H4) induced emission of PMs has the property of aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT), which could effectively address the notorious aggregation-caused quenching (ACQ) effects of conventional organic dyes. In addition, the cross-linking strategy can not only improve structural stability of PMs but also enhance its fluorescence brightness. The experiment results demonstrated that PMs showed high water dispersibility (100% aqueous solution), high selectivity, large Stokes shift (∼150 nm), good photostability, and excellent long-term stability. Because of the hydrophobic interaction between the PMs and fingerprint components, the PMs preferentially adhered onto the ridges of fingerprint, and then cross-linking (N2H4) induced emission properties endowed the PMs for high-contrast imaging of LFPs in different substrates, especially the levels 1-3 details of LFPs. We expect that this strategy will provide vital support for LFPs technology.

Preparation, characterization, evaluation and mechanistic study of organic polymer nano-photocatalysts for solar fuel production.

Production of renewable fuels from solar energy and abundant resourses, such as water and carbon dioxide, via photocatalytic reactions is seen as a promising strategy to adequately address the climate challenge. Photocatalytic systems based on organic polymer nanoparticles (PNPs) are seen as one avenue to transform solar energy into hydrogen and other solar fuels. Semiconducting PNPs are light-harvesting materials with exceptional optical properties, photostability, low cost and low cytotoxity, whose performance surpasses conventional organic dyes and inorganic semiconductors. This review introduces the optimization strategies for the preparation methods of PNP via cocatalyst loading and morphology tuning. We present an analysis on how the preparative methods will impact the physico-chemical properties of these materials, and thus the catalytic activity. A list of experimental techniques is presented for characterization of the physico-chemical properties (optical, morphological, electrochemical and catalytic properties) of PNPs. We provide detailed analysis of PNP photochemistry during photocatalysis with focus on the mechanistic understanding of processes of internal charge generation and transport to the catalyst. This tutorial review provides the reader with the guidelines on current strategies used to optimize PNP performance highlighting the future directions of polymer nano-photocatalysts development.

A simple strategy to enhance the luminescence of metal nanoclusters and its application for turn-on detection of 2-thiouracil and hyaluronidase

Metal nanoclusters (NCs) as promising nanomaterials for sensing applications have attracted significant attention because of their unique photoluminescence properties. However, the quantum yields of metal NCs are still relatively low when compared to conventional quantum dots and organic dyes, posing a major obstacle to their assay application. It is challenging but important to pursue a way to improve the luminescence of metal NCs. In this work, we developed a novel strategy to enhance the luminescence of silver nanoclusters (Ag NCs) based on the binding with 6-aza-2-thiothymine (ATT) via Au3+ bridging. We studied the possible mechanism of this binding-induced luminescence enhancement and attributed it to the ligands rigidifying. Since 2-thiouracil (2-TU), a common anticancer, antithyroid, and antiviral agent, featured a similar molecular structure of ATT, this luminescence enhancement strategy can be designed to sensitive and selective turn-on detect 2-TU. As far as we know, this is the first report for the fluorescent turn-on detect 2-TU. Benefiting from the good performance of this method and the advantages of fluorescence assay, intracellular imaging of 2-TU, which has yet to be achieved based on currently developed analytical methods for 2-TU, was carried out via our approach. Moreover, to further expand the sensing application of the developed luminescence enhancement method, we constructed a universal detection platform. Taking hyaluronidase as a target, the feasibility of the detection platform was confirmed. The discoveries in this study offer a simple route to improve the optical properties of NCs and design their sensing applications.

Frontier luminous strategy of functional silica nanohybrids in sensing and bioimaging: From ACQ to AIE

AbstractFluorescent silica organic–inorganic nanohybrids which combine designable luminescence performance of organic fluorescent dyes and various outstanding advantages of silica nanomaterials have attracted increasing research interests in these fascinating areas. Optical transparency and facile functional modification properties of silica material provide great opportunities to integrate desired fluorescent molecules for various frontier luminous applications. However, conventional organic dyes are typically subject to aggregation‐caused quenching due to their aggregation in silica matrix, which could be detrimental for their performance in sensing and biomedical applications. The appearance of aggregation‐induced emission luminogens (AIEgens) paves a new way for developing highly efficient fluorescent silica nanohybrids (FSNs). FSNs with intensive luminescence could be obtained due to the formation of aggregates and the restricted intramolecular motion of AIEgens in silica inorganic matrix. In this review, the reported fabrication methodologies of various FSNs based on colloidal silica nanoparticles (SNs) and mesoporous SNs including physical entrapment and covalent strategies are summarized. Especially, the AIEgens‐functionalized silica hybrid nanomaterials are introduced in detail. Furthermore, chemical sensing, biosensing, and bioimaging applications of resultant FSNs are also discussed.

Glutamic acid-assisted hydrothermal recrystallization to configure bamboo-like carbon nanotubes for improved triiodide reduction

Carbon nanotubes (CNTs) have been far and wide employed as the counter electrodes (CEs) in dye-sensitized solar cells because of their individual physical and chemical properties. However, the techniques available now, such as chemical vapor deposition, arc discharge and laser ablation for synthesizing CNTs, commonly suffer from rigorous operations and complicated steps, which make the process difficult to be controlled. Herein, we present a simple and facile glutamic acid-assisted hydrothermal recrystallization strategy to construct bamboo-like CNTs (GHP-BC- x ). Generally, the conventional organic dye 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) is used as a precursor and glutamic acid efficiently promotes the recrystallization of the perylene cores’ planar π-conjugated system in PTCDA under hydrothermal conditions and then self-assembles into one-dimensional nanorods with improved crystallization degree, finally resulting in the morphology of bamboo-like CNTs after carbonization. When applied as the counter electrodes, the GHP-BC-3 displays a remarkable power conversion efficiency of 8.25%, benefiting from the superb electrical conductivity and mass transfer dynamics, superior to that of Pt CE (7.62%).

An Exceptional Broad-Spectrum Nanobiocide for Multimodal and Synergistic Inactivation of Drug-Resistant Bacteria

An Exceptional Broad-Spectrum Nanobiocide for Multimodal and Synergistic Inactivation of Drug-Resistant Bacteria

Molecularly imprinted polymers based on magnetically fluorescent metal–organic frameworks for the selective detection of hepatitis A virus

A novel fluorescent molecularly imprinted polymers (MIPs) sensor based on a magnetic metal–organic framework (MOF) was prepared and applied in the detection of the weakly fluorescent hepatitis A virus (HAV). Luminescent MOFs can be used as both output signals and carriers; thus, a luminescent MOF (MIL-101-NH2) was used to replace conventional quantum dots and organic dyes for generating the fluorescence output signal. The constructed MIP sensor demonstrated excellent selectivity for the template recognition entities as well as a high detection sensitivity. Over the concentration range of 0.02–2.5 nM, the sensor had a detection limit of 3 pM, and a correlation coefficient of 0.997 was calculated by plotting the concentrations of the template virus against their respective fluorescence intensities. In addition, viruses were detected within 15 min by the prepared nanoparticles and remained highly selective in binary competition assays in the presence of HAV. As a result, the method developed in this work was simple, rapid, and could be used to detect HAV qualitatively and quantitatively. It has the potential to be used as a biosensor for the detection of weakly fluorescent or non-fluorescent viruses.

Multiphoton Deep-Tissue Imaging of Micrometastases and Disseminated Cancer Cells Using Conjugates of Quantum Dots and Single-Domain Antibodies.

Early detection of malignant tumors, micrometastases, and disseminated tumor cells is one of the effective way of fighting cancer. Among the many existing imaging methods like computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT), optical imaging with fluorescent probes is one of the most promising alternatives because it is fast, inexpensive, safe, sensitive, and specific. However, traditional fluorescent probes, based on organic fluorescent dyes, suffer from the low signal-to-noise ratio. Furthermore, conventional organic fluorescent dyes are unsuitable for deep tissue imaging because of the strong visible light absorption by biological tissues. The use of fluorescent semiconductor nanocrystals, or quantum dots (QDs), may overcome this limitation due to their large multiphoton cross section, which ensures efficient imaging of thick tissue sections inaccessible with conventional fluorescent probes. Moreover, the lower photobleaching and higher brightness of fluorescence signals from QDs ensures a much better discrimination of positive signals from the background. The use of fluorescent nanoprobes based on QDs conjugated to uniformly oriented high-affinity single-domain antibodies (sdAbs) may significantly increase the sensitivity and specificity due to better recognition of analytes and deeper penetration into tissues due to small size of such nanoprobes.Here, we describe a protocol for the fabrication of nanoprobes based on sdAbs and QDs, preparation of experimental xenograft mouse models for quality control, and multiphoton imaging of deep-tissue solid tumors, micrometastases, and disseminated tumor cells.