Infrared Dye Research Articles

Gel-like Carbon Dots: Characterization and their Potential Applications.

Highly photoluminescent gel-like carbon dots (G-CDs) were successfully synthesized for the first time by a rapid one-step solvothermal synthesis approach with citric acid and 1,2-ethylenediamine as the precursors. Their gel-like nature was revealed by the Tyndall and coagulation effects, which were elucidated by a negative ζ potential value. The influences of temperature on the properties and sizes of these G-CDs were analyzed, and the best method for a maximum quantum yield was identified. The resulting products emitted blue photoluminescence under UV light (λ=365 nm) and a gradient of color under regular light. In addition, the UV/Vis absorption and fluorescence emission spectra of the G-CDs indicated that those synthesized at 160 °C exhibited the highest fluorescence quantum yield (33 %). Atomic force microscopy and transmission electron microscopy measurements were performed, and a higher temperature of formation resulted in smaller G-CDs. Furthermore, band shifts in the UV/Vis and fluorescence spectra and sequential changes in the quantum yield values and ζ potentials in addition to elemental compositional changes as determined by X-ray photoelectron spectroscopy were monitored throughout the formation process of the G-CDs. As to applications, G-CDs were prepared as an invisible ink for printers, which exhibited the applicability of G-CDs in daily life and military activities.

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex

Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose.

Photophysical characterization and BSA interaction of the direct ring carboxy functionalized unsymmetrical NIR cyanine dyes

Novel near infrared (NIR) sensitive unsymmetrical cyanine dyes bearing direct –COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations. These unsymmetrical cyanine dyes were then subjected to investigate their interaction with bovine serum albumin (BSA) as a model protein in Phosphate buffer solutions. Apart from NIR absorption and emission with high molar extinction coefficients they exhibit a blue shift in PBS solution owing to their enhanced dye aggregation. Interaction of these dyes with BSA leads to not only enhanced emission intensity but also bathochromically shifted absorption maximum due to formation of dye-BSA conjugate. These dyes bind strongly with BSA having about an order of magnitude higher binding constant as compared to the typical cyanine dyes. Amongst the unsymmetrical cyanine dyes investigated in this work one bearing substituents like Iodo and carboxylic acid in the terminal Indole rings (UCD-3) exhibited highest association with the BSA having very high binding constant of 1.01 × 107 M−1.

Detection of microspheres in vivo using multispectral optoacoustic tomography

We introduce a new approach to detect individual microparticles that contain NIR fluorescent dye by multispectral optoacoustic tomography in the context of the hemoglobin-rich environment within murine liver. We encapsulated a near infrared (NIR) fluorescent dye within polystyrene microspheres, then injected them into the ileocolic vein, which drains to the liver. NIR absorption was determined using multispectral optoacoustic tomography. To quantitate the minimum diameter of microspheres, we used both colorimetric and spatial information to segment the regions in which the microspheres appear. Regional diameter was estimated by doubling the maximum regional distance. We found that the minimum microsphere size threshold for detection by multispectral optoacoustic tomography images is 78.9 µm.

Simple Techniques to Reveal Invisible Ink in Forensic Science

Secret writing is a hidden writing which is used to convey a message as a means of communication. Invisible inks are used to write secret messages such as fruit juice, vegetable juice and by some chemicals also. This paper is about secret writing which can reveal from heating and how it is important in forensic science. The current research paper comprises of some samples which will help to specify and identify the secret writing and then they visualised by physical method and chemical method.

Highly fluorescent nitrogen-doped carbon dots with excellent thermal and photo stability applied as invisible ink for loading important information and anti-counterfeiting.

High quantum yields (QY) and stable performances are prerequisites for implementing carbon dots in practical applications. In this study, we demonstrate that nitrogen-doped carbon dots (N-CDs), which were prepared via the hydrothermal treatment of citric acid (CA) and tris(hydroxymethyl)methyl aminomethane (Tris), have a high QY of 75%, together with excellent thermal and photo stability. These N-CDs deliver an excellent thermal stability performance over the temperature range of 25 °C to 95 °C, and even at a heating temperature of 90 °C for 360 min. Upon exposure to UV illumination with a radiant intensity of 20 mW cm-2, 96% fluorescence intensity is retained. This florescence stability performance is probably due to the chemical composition and steric effect of the nitrogen-doping agent. Furthermore, the remarkable optical properties of these N-CDs allow them to be used as invisible ink for loading important information and advanced anti-counterfeiting.

Epicocconone-Hemicyanine Hybrids: Near Infrared Fluorophores for Protein Staining and Cell Imaging.

The development of new near infrared (NIR) dyes is crucial for diverse applications and especially bioimaging, as they absorb and emit light in the "therapeutic window" (650-950 nm). We report here a new family of NIR fluorophores that has been obtained by hybridising hemicyanines with epicocconone. Emission wavelengths of these hybrid dyes is in the range 715-795 nm and is combined with large Stokes' shifts (75-95 nm). The absorption and emission wavelength can be modulated according to the hemicyanine moiety and adding sulfonic acid moieties enhances water solubility. We demonstrate their application in the sensitive detection of proteins in gel electrophoresis and the staining of specific cellular organelles in confocal microscopy. These results are particularly encouraging and bring forward a new fluorescent skeleton for chemical biology.

Selective Host–Guest Co‐crystallization of Pyridine‐Functionalized Tetraphenylethylenes with Phthalic Acids and Multicolor Emission of the Co‐crystals

Tetraphenylethylene (TPE) and its derivatives are the most typical and most widely studied organic compounds showing aggregation-induced emission (AIE). Due to their propeller-like structures, V-like clefts exist between the aryl rings, which make them promising host compounds. However, such a possibility is seldom explored. Herein, it is reported that TPE derivatives bearing two or four pyridine rings at the para positions of the phenyl rings (TPE-Pys) can selectively include triangular (Δ-like) m-phthalic acid from a mixture of o-, m-, and p-phthalic acids due to their shape complementary to form host-guest co-crystals, which showed redder emission than the TPE-Pys themselves. The emission of co-crystals 1-5 could be reversibly switched between yellow and red by alternating exposure to HCl and ammonia vapor. The host-guest co-crystals not only exhibited great potential for selectively recognizing and separating m-phthalic acid and as multicolor emission materials, but are also suitable for use as secret ink due to their reversible color change on varying the host-guest interactions.

ChemInform Abstract: Diradical Approach Toward Organic Near Infrared Dyes

AbstractReview: [47 refs.

Abstract 2191: Imaging the kinetics of targeted nanoparticles to pancreatic cancer

Abstract Purpose: The purpose of this work is to image the kinetics of targeted lipid nanoparticles to an SCL transporter of pancreatic cancer using a near infrared (NIR) fluorescent dye DyLight® 747 and a mouse orthotopic model of fluorescent pancreatic cancer. Methods: Initially and before the in vivo experiments, the uptake of nanoparticles by human pancreatic cancer cells was evaluated in vitro using fluorescent microscopy and flow cytometry. A quantity of 1.5 x105 PANC-1, MIA PaCa, or BxPC-3 cells/ml was placed in each well of a six-well plate and incubated for 5 hours with different formulations of fluorescent lipid targeted and non-targeted nanoparticles encapsulation daunorubicin which has natural fluorescence. After incubation, the growth media were removed and the cells were washed with PBS. The uptake of the fluorescent lipid nanoparticles by the cancer cells was evaluated an EVOS® microscope. All the in vitro experiments were done in triplicate. For the in vivo targeting studies, nude mice (Balb/c Ola Hsd-Fox1 nu) were implanted orthotopically (in the tail of the pancreas) with 3 x106 PANC-1 cells expressing GFP. The injection volume for the implantation was 50 microliters and contained 3 x106 PANC-1-GFP cells mixed with serum free media and HC Matrigel (1:1). One month after the orthotopic implantation, the implanted pancreatic tumor was visualized in live, anesthetized animals using UVP Scientia (UVP, Upland, CA). The animals were separated into three groups (three animals in each group) and injected via the tail vein as follows: Group A, was injected with only the fluorescent dye, Dylight 747; group B was injected with fluorescent non-targeted nanoparticles; and group C was injected with fluorescent targeted nanoparticles. Results: Both the flow cytometry and fluorescence microscopy data show a significantly higher uptake of the targeted lipid nanoparticles compared to the non-targeted ones. The imaging of the fluorescent lipid nanoparticles in live mice shows that both targeted and nontargeted nanoparticles reach the pancreatic tumor. The nontargeted nanoparticles reside less than 48 hours on the tumor, whereas the targeted nanoparticles can reside for 96 hours on the tumor. The non-encapsulated fluorescent dye did not reach the tumor and was excreted in the urine. Conclusion: The results show that Dylight® 747 can be used to image the kinetics of a drug delivery system in a live animal. Furthermore while both lipid nanoparticles reach the tumor, the targeted lipid nanoparticles reside significantly longer on the tumor and this may translate to a better therapeutic outcome. Citation Format: Jonathan Moreno, Qin qin Fei, Maria P. Lambros. Imaging the kinetics of targeted nanoparticles to pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2191.

‘The terrible things I’ve done’: undisciplined subjectivity of the cyborg within intermedial performance practice

ABSTRACTIn 15-minute slots, theatre company Invisible Ink invited participants to enter a room by themselves, make a call on a rotary phone, and tell an answering machine about a terrible thing they had done and how they felt about it. In this paper I argue that the body of each participant, in the moment of speaking into the phone, became a cyborg body, producing a new form of cyber-subjectivity by revealing an abjected story. I examine this moment as an instance of rupture in the disciplinary processes of self-curation through the strategic use of intermediality.

Dual targeting luminescent gold nanoclusters for tumor imaging and deep tissue therapy

Dual targeting towards both extracellular and intracellular receptors specific to tumor is a significant approach for cancer diagnosis and therapy. In the present study, a novel nano-platform (AuNC-cRGD-Apt) with dual targeting function was initially established by conjugating gold nanocluster (AuNC) with cyclic RGD (cRGD) that is specific to αvβ3integrins over-expressed on the surface of tumor tissues and aptamer AS1411 (Apt) that is of high affinity to nucleolin over-expressed in the cytoplasm and nucleus of tumor cells. Then, AuNC-cRGD-Apt was further functionalized with near infrared (NIR) fluorescence dye (MPA), giving a NIR fluorescent dual-targeting probe AuNC-MPA-cRGD-Apt. AuNC-MPA-cRGD-Apt displays low cytotoxicity and favorable tumor-targeting capability at both in vitro and in vivo level, suggesting its clinical potential for tumor imaging. Additionally, Doxorubicin (DOX), a widely used clinical chemotherapeutic drug that kill cancer cells by intercalating DNA in cellular nucleus, was immobilized onto AuNC-cRGD-Apt forming a pro-drug, AuNC-DOX-cRGD-Apt. The enhanced tumor affinity, deep tumor penetration and improved anti-tumor activity of this pro-drug were demonstrated in different tumor cell lines, tumor spheroid and tumor-bearing mouse models. Results in this study suggest not only the prospect of non-toxic AuNC modified with two targeting ligands for tumor targeted imaging, but also confirm the promising future of dual targeting AuNC as a core for the design of prodrug in the field of cancer therapy.

Message in a molecule.

Since ancient times, steganography, the art of concealing information, has largely relied on secret inks as a tool for hiding messages. However, as the methods for detecting these inks improved, the use of simple and accessible chemicals as a means to secure communication was practically abolished. Here, we describe a method that enables one to conceal multiple different messages within the emission spectra of a unimolecular fluorescent sensor. Similar to secret inks, this molecular-scale messaging sensor (m-SMS) can be hidden on regular paper and the messages can be encoded or decoded within seconds using common chemicals, including commercial ingredients that can be obtained in grocery stores or pharmacies. Unlike with invisible inks, however, uncovering these messages by an unauthorized user is almost impossible because they are protected by three different defence mechanisms: steganography, cryptography and by entering a password, which are used to hide, encrypt or prevent access to the information, respectively.

Fluorescent Polystyrene Microbeads as Invisible Security Ink and Optical Vapor Sensor for 4-Nitrotoluene

Color-tunable solid-state emitting polystyrene (PS) microbeads were developed by dispersion polymerization, which showed excellent fluorescent security ink characteristics along with sensitive detection of vapors of nitro aromatics like 4-nitro toluene (4-NT). The fluorophores pyrene and perylenebisimide were incorporated into the PS backbone as acrylate monomer and acrylate cross-linker, respectively. Solid state quantum yields of 94 and 20% were observed for the pyrene and perylenebisimide, respectively, in the PS/Py and PS/PBI polymers. The morphology and solid state fluorescence was measured by SEM, fluorescence microscopy, and absorbance and fluorescence spectroscopy techniques. The ethanol dispersion of the polymer could be used directly as a fluorescent security "invisible" ink, which became visible only under ultraviolet light. The color of the ink could be tuned depending on the amounts of the pyrene and perylenebisimide incorporated with blue and orange-green for pyrene alone or perylenebisimide alone beads respectively and various shades in between including pure white for beads incorporating both the fluorophores. More than 80% quenching of pyrene emission was observed upon exposure of the polymer in the form of powder or as spin-coated films to the vapors of 4-NT while the emission of perylenebisimide was unaffected. The limit of detection was estimated at 10(-5) moles (2.7 ppm) of 4-NT vapors. The ease of synthesis of the material along with its invisible ink characteristics and nitro aromatic vapor detection opens up new opportunities for exploring the application of these PS-based materials as optical sensors and fluorescent ink for security purposes.

Photophysical investigations of squaraine and cyanine dyes and their interaction with bovine serum albumin

A model far-red sensitive symmetrical squaraine dye (SQ-3) and unsymmetrical near infra-red sensitive cyanine dye (UCD-1) bearing direct–COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations including their interaction with bovine serum albumin (BSA) as a model protein in phosphate buffer solution (PBS). Both of the dyes exhibit strong interaction with BSA in phosphate buffer with high apparent binding constant. A judicious tuning of hydrophobic main backbone with reactive functionality for associative interaction with active site of BSA has been found to be necessary for BSA detection in PBS.

In vivo Near-infrared Fluorescence Tumor Imaging Using DiR-loaded Nanocarriers.

The hydrophobic long-chain dialkylcarbocyanine 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) is an important near infrared (NIR) fluorescent dye, which has a satisfactory photo stability for continuous excitation. During the past decade, it has been widely used for in vivo monitoring of cells. With the fast emergence of novel tumor-targeted nanocarriers, the applications of DiR in the development of fluorescent or multifunctional nano-probes for in vivo tumor imaging are also reported. In these studies, DiR-loaded nanocarriers have resulted in good fluorescence images, indicating the great potential of this dye. However, some important issues about DiR-loaded nanocarriers were often overlooked. These issues include the in vivo fluorescent properties, stability, toxicity, retention and metabolization of DiR-loaded nanocarriers. This review introduced the current use and the properties of DiR-loaded nanocarriers for in vivo tumor imaging. The perspective outlook at the last section highlights the future application of DiR-loaded nanocarriers.

Infra Red Dye and Endostar Loaded Poly Lactic Acid Nano Particles as a Novel Theranostic Nanomedicine for Breast Cancer.

Endostar, a novel recombinant human endostatin, has been proven to inhibit tumor angiogenesis and is utilized as an anticancer drug. While free drugs can display limited efficacy, nanoscaled anticancer drugs have been fabricated and proven to possess superior therapeutic effects. Poly(lactic acid) (PLA) is a FDA-approved biomaterial displaying excellent biocompatibility and low toxicity. In this study, Endostar-loaded PLA nanoparticles (EPNPs) were first prepared, and a near-infrared (NIR) dye, IRDye 800CW, was conjugated to the surface for detecting nanoparticle biodistribution through fluorescence molecular imaging (FMI) using an orthotopic breast tumor mouse model. The antitumor efficacy of EPNPs was examined using bioluminescence imaging (BLI) and immunohistology. To further improve the antitumor effects, we combined EPNPs with zoledronic acid monohydrate (ZA), which is known to decrease the tumor-associated macrophages (TAM) and inhibit tumor progression. We found that EPNPs decreased human umbilical vein endothelial cell (HUVEC) viability by inhibiting tumor growth gene expression more significantly than free Endostar in vitro. In vivo, EPNPs displayed better tumor growth inhibitory effects compared with free Endostar, and the combination of EPNPs with ZA exhibited more significant antitumor effects. As confirmed by CD31 and CD11b immunohistochemistry, the combination of EPNPs and ZA showed synergistic effects in reducing tumor angiogenesis and TAM accumulation in tumor regions. Taken together, this study presents a novel and effective form of nanoscaled Endostar for the treatment of breast cancer that displays synergistic antitumor effects in combination with ZA.

Invisible Security Ink Based on Water-Soluble Graphitic Carbon Nitride Quantum Dots.

Stimuli-responsive photoluminescent (PL) materials have been widely used as fluorescent ink for data security applications. However, traditional fluorescent inks are limited in maintaining the secrecy of information because the inks are usually visible by naked eyes either under ambient light or UV-light illumination. Here, we introduced metal-free water-soluble graphitic carbon nitride quantum dots (g-CNQDs) as invisible security ink for information coding, encryption, and decryption. The information written by the g-CNQDs is invisible in ambient light and UV light, but it can be readable by a fluorescence microplate reader. Moreover, the information can be encrypted and decrypted by using oxalic acid and sodium bicarbonate as encryption reagent and decryption reagent, respectively. Our findings provide new opportunities for high-level information coding and protection by using water-soluble g-CNQDs as invisible security ink.

Invisible Security Ink Based on Water‐Soluble Graphitic Carbon Nitride Quantum Dots

AbstractStimuli‐responsive photoluminescent (PL) materials have been widely used as fluorescent ink for data security applications. However, traditional fluorescent inks are limited in maintaining the secrecy of information because the inks are usually visible by naked eyes either under ambient light or UV‐light illumination. Here, we introduced metal‐free water‐soluble graphitic carbon nitride quantum dots (g‐CNQDs) as invisible security ink for information coding, encryption, and decryption. The information written by the g‐CNQDs is invisible in ambient light and UV light, but it can be readable by a fluorescence microplate reader. Moreover, the information can be encrypted and decrypted by using oxalic acid and sodium bicarbonate as encryption reagent and decryption reagent, respectively. Our findings provide new opportunities for high‐level information coding and protection by using water‐soluble g‐CNQDs as invisible security ink.

Acoustic Cluster Therapy (ACT) — pre-clinical proof of principle for local drug delivery and enhanced uptake

Proof of principle for local drug delivery with Acoustic Cluster Therapy (ACT) was demonstrated in a human prostate adenocarcinoma growing in athymic mice, using near infrared (NIR) dyes as model molecules. A dispersion of negatively charged microbubble/positively charged microdroplet clusters are injected i.v., activated within the target pathology by diagnostic ultrasound (US), undergo an ensuing liquid-to-gas phase shift and transiently deposit 20–30μm large bubbles in the microvasculature, occluding blood flow for ~5–10min. Further application of low frequency US induces biomechanical effects that increase the vascular permeability, leading to a locally enhanced extravasation of components from the vascular compartment (e.g., released or co-administered drugs). Results demonstrated deposition of activated bubbles in tumor vasculature. Following ACT treatment, a significant and tumor specific increase in the uptake of a co-administered macromolecular NIR dye was shown. In addition, ACT compound loaded with a lipophilic NIR dye to the microdroplet component was shown to facilitate local release and tumor specific uptake. Whereas the mechanisms behind the observed increased and tumor specific uptake are not fully elucidated, it is demonstrated that the ACT concept can be applied as a versatile technique for targeted drug delivery.