Dye-doped Nanoparticles Research Articles

Detection of Tn-antigen in breast and prostate cancer models by VVL-labeled red dye-doped nanoparticles.

Aim: Fluorescence detection of breast and prostate cancer cells expressing Tn-antigen, a tumor marker, with Vicia villosa lectin (VVL)-labeled nanoparticles.Materials & methods: Breast and prostate cancer cells engineered to express high levels of Tn-antigen and non-engineered controls were incubated with VVL-labeled or unlabeled red dye-doped silica-coated polystyrene nanoparticles. The binding to cells was studied with flow cytometry, confocal microscopy, and electron microscopy.Results: Flow cytometry showed that the binding of VVL-labeled nanoparticles was significantly higher to Tn-antigen-expressing cancer cells than controls. Confocal microscopy demonstrated that particles bound to the cell surface. According to the correlative light and electron microscopy the particles bound mostly as aggregates.Conclusion: VVL-labeled nanoparticles could provide a new tool for the detection of Tn-antigen-expressing breast and prostate cancer cells.

Iterative nanoparticle bioengineering enabled by x-ray fluorescence imaging.

Nanoparticles (NPs) are currently developed for drug delivery and molecular imaging. However, they often get intercepted before reaching their target, leading to low targeting efficacy and signal-to-noise ratio. They tend to accumulate in organs like lungs, liver, kidneys, and spleen. The remedy is to iteratively engineer NP surface properties and administration strategies, presently a time-consuming process that includes organ dissection at different time points. To improve this, we propose a rapid iterative approach using whole-animal x-ray fluorescence (XRF) imaging to systematically evaluate NP distribution in vivo. We applied this method to molybdenum-based NPs and clodronate liposomes for tumor targeting with transient macrophage depletion, leading to reduced accumulations in lungs and liver and eventual tumor detection. XRF computed tomography (XFCT) provided 3D insight into NP distribution within the tumor. We validated the results using a multiscale imaging approach with dye-doped NPs and gene expression analysis for nanotoxicological profiling. XRF imaging holds potential for advancing therapeutics and diagnostics in preclinical pharmacokinetic studies.

Synthesis and Characterization of Dye-Doped Au@SiO2 Core-Shell Nanoparticles for Super-Resolution Fluorescence Microscopy.

Dye-doped nanoparticles have been investigated as bright, fluorescent probes for localization-based super-resolution microscopy. Nanoparticle size is important in super-resolution microscopy to get an accurate size of the object of interest from image analysis. Due to their self-blinking behavior and metal-enhanced fluorescence (MEF), Ag@SiO2 and Au@Ag@SiO2 nanoparticles have shown promise as probes for localization-based super-resolution microscopy. Here, several noble metal-based dye-doped core-shell nanoparticles have been investigated as self-blinking nanomaterial probes. It was observed that both the gold- and silver-plated nanoparticle cores exhibit weak luminescence under certain conditions due to the surface plasmon resonance bands produced by each metal, and the gold cores exhibit blinking behavior which enhances the blinking and fluorescence of the dye-doped nanoparticle. However, the silver-plated nanoparticle cores, while weakly luminescent, did not exhibit any blinking; the dye-doped nanoparticle exhibited the same behavior as the core fluorescent, but did not blink. Because of the blinking behavior, stochastic optical reconstruction microscopy (STORM) super-resolution analysis was able to be performed with performed on the gold core nanoparticles. A preliminary study on the use of these nanoparticles for localization-based super-resolution showed that these nanoparticles are suitable for use in STORM super resolution. Resolution enhancement was two times better than the diffraction limited images, with core sizes reduced to 15 nm using the hybrid Au-Ag cores.

Role of Aqueous-Phase Calcination in Synthesis of Ultra-Stable Dye-Embedded Fluorescent Nanoparticles for Cellular Probing.

Fluorescence imaging is a major driver of discovery in biology, and an invaluable asset in clinical diagnostics. To overcome quenching limitations of conventional fluorescent dyes and further improve intensity, nanoparticle-based constructs have been the subject of intense investigation, and within this realm, dye-doped silica-coated nanoparticles have garnered significant attention. Despite their growing popularity in research, fluorescent silica nanoparticles suffer from a significant flaw. The degradation of these nanoparticles in biological media by hydrolytic dissolution is underreported, leading to serious misinterpretations, and limiting their applicability for livecellandinvivoimaging. Here, the development of an ultra-stable, dye-embedded, silica-coated metal nanoparticle is reported, and its superior performance in long-term live cell imaging is demonstrated. While conventional dye-doped silica nanoparticles begin to degrade within an hour in aqueous media, by leveraging a modified liquid calcination process, this new construct is shown to be stableforat least 24 h.The stability of this metal-enhanced fluorescent probe in biologically relevant temperatures and media, and its demonstrated utility for cell imaging, paves the way for its future adoption in biomedical research.

Degenerate Four-Wave Mixing in Phycoerythrin Dye-Doped Nanoparticles

We have generated a phase-conjugate (PC) wave from nanoparticles with a new microscopic system proposed. The microscope includes a confocal system with a degenerate four-wave mixing (DFWM) system, which plays a major role in generating the phase-conjugate wave to compensate phase distortion in the optical path toward targets. The proposed optical system detects feeble PC wave and imagines 3D particles while improving the inplane contrast resolution of the microscopic image.

Tandem Dye-Doped Nanoparticles for NIR Imaging via Cerenkov Resonance Energy Transfer.

The detection of the Cerenkov radiation (CR) is an emerging preclinical imaging technique which allows monitoring the in vivo distribution of radionuclides. Among its possible advantages, the most interesting is the simplicity and cost of the required instrumentation compared, e.g., to that required for PET scans. On the other hand, one of its main drawbacks is related to the fact that CR, presenting the most intense component in the UV-vis region, has a very low penetration in biological tissues. To address this issue, we present here multifluorophoric silica nanoparticles properly designed to efficiently absorb the CR radiation and to have a quite high fluorescence quantum yield (0.12) at 826 nm. Thanks to a highly efficient series of energy transfer processes, each nanoparticle can convert part of the CR into NIR light, increasing its detection even under 1.0-cm thickness of muscle.

Core size does not affect blinking behavior of dye-doped Ag@SiO2 core–shell nanoparticles for super-resolution microscopy

Dye-doped nanoparticles have been investigated as bright, luminescent labels for super-resolution microscopy via localization methods. One key factor in super-resolution is the size of the luminescent label, which in some cases results in a frame shift between the label target and the label itself. Ag@SiO2 core–shell nanoparticles, doped with organic fluorophores, have shown promise as super-resolution labels. One key aspect of these nanoparticles is that they blink under certain conditions, allowing super-resolution localization with a single excitation source in aqueous solution. In this work, we investigated the effects of both the Ag core and the silica (SiO2) shell on the self-blinking properties of these nanoparticles. Both core size and shell thickness were manipulated by altering the reaction time to determine core and shell effects on photoblinking. Size and shell thickness were investigated individually under both dry and hydrated conditions and were then doped with a 1 mM solution of Rhodamine 110 for analysis. We observed that the cores themselves are weakly luminescent and are responsible for the blinking observed in the fully-synthesized metal-enhanced fluorescence nanoparticles. There was no statistically significant difference in photoblinking behavior—both intensity and duty cycle—with decreasing core size. This observation was used to synthesize smaller nanoparticles ranging from approximately 93 nm to 110 nm as measured using dynamic light scattering. The blinking particles were localized via super-resolution microscopy and show single particle self-blinking behavior. As the core size did not impact blinking performance or intensity, the nanoparticles can instead be tuned for optimal size without sacrificing luminescence properties.

Surface Modification of Fluorescent Nanodiamond for Biomedical Applications as Fluorescent Probe

Fluorescent nanodiamonds (FNDs) are promising bio-imaging probes compared with other fluorescent nanomaterials such as quantum dots, dye-doped nanoparticles, and metallic nanoclusters due to their unique optical properties and excellent biocompatibility. Nevertheless, they are prone to aggregation in physiological salt solutions, and modifying their surface to conjugate biologically active agents remains challenging. We describe encapsulation of FNDs into polydopamine (PDA) shells, which is inspired by the adhesive protein of marine mussels. The PDA shells can be further functionalized via Michael addition or Schiff base reactions with molecules presenting thiol or nitrogen derivatives. We demonstrate PDA shells modified by thiol terminated polyethylene glycol (PEG) molecules, which enhance stability in biological solutions and biocompatibility of PDA coated FND ([email protected]). The PEG modified [email protected] nanoparticles were utilized as fluorescent probes for cell imaging with immature bone marrow derived dendritic cells. Furthermore, functionalization with biotin-PEG-SH permitted long-term high-resolution single-molecule fluorescence-based tracking of FNDs tethered via streptavidin to individual biotinylated DNA molecules. This robust polydopamine encapsulation and functionalization strategy presents a facile route to develop FNDs as multifunctional labels, drug delivery vehicles, and targeting agents for biomedical applications.

Controllable wavelength-selective optical composite based on nano-polymeric films with doped dyes

The novel color optical composites with controllable light absorption from the solar energy based on polyvinyl alcohol (PVA) as matrix materials were investigated. The nanoparticles with molecular level dye-doped were prepared by microemulsion polymerization. The structure and morphology of the nanoparticles and the color nano-films were characterized by Fourier transform infrared spectrum (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analysis. Three nanoparticles with dye-doped are all homogeneous nanospheres with regular shape and size of 50–70 nm. Three PVA color films containing nanoparticles possess different absorption bands in the visible light region. A controlled sunlight absorption film filter using dye-doped nanoparticles can be arbitrarily designed and assembled by adjusting the recipe to selectively transmit specific wavelengths from sunlight. Because the dye molecules are stabilized in the nanoparticles, the absorption band of the membranes can be precisely controlled. It can be conveniently assembled or deposited on other substrates to form nano-membranes. The composite containing color nanoparticles is simple, flexible, and cost-effective. They have potential applications in many fields, such as energy, agriculture, environment and biotechnology.

An improved class of fluorescent silica nanoparticles for indirect immunofluorescence detection of MCF-7 cells

In this work, we have developed an efficient method based on silica fluorescent dye-doped nanoparticles and second antibody for cancer cell labeling. The dye-doped silica nanoparticles were synthesized by the reverse microemulsion method with the conjugate of 3-aminopropyltriethoxysilane and rhodamine B isothiocynate. A PEG with flexible long chain as the bridge was introduced onto the surface of the nanoparticle via cyanogens bromide method. The second antibody, goat anti-rabbit IgG, was conjugated on the surface of the PEG-terminal modified silica fluorescent nanoparticles by covalent binding to the PEG linkers via the EDC/sulfo-NHS method. The concentrations of goat anti-rabbit IgG covering the nanoparticles were quantified via the Bradford method. The silica fluorescent nanoparticles functionalized with rabbit anti-MUC1 antibody were employed as bioprobes for the recognition of MUC1 protein in human breast carcinoma molecules MCF-7 cells. Compared with fluorescent dye labeled IgG, the fluorescent nanoprobes display dramatically increased photostability.

Polydopamine encapsulation of fluorescent nanodiamonds for biomedical applications.

Fluorescent nanodiamonds (FNDs) are promising bio-imaging probes compared with other fluorescent nanomaterials such as quantum dots, dye-doped nanoparticles, and metallic nanoclusters, due to their remarkable optical properties and excellent biocompatibility. Nevertheless, they are prone to aggregation in physiological salt solutions, and modifying their surface to conjugate biologically active agents remains challenging. Here, inspired by the adhesive protein of marine mussels, we demonstrate encapsulation of FNDs within a polydopamine (PDA) shell. These PDA surfaces are readily modified via Michael addition or Schiff base reactions with molecules presenting thiol or nitrogen derivatives. We describe modification of PDA shells by thiol terminated poly(ethylene glycol) (PEG-SH) molecules to enhance colloidal stability and biocompatibility of FNDs. We demonstrate their use as fluorescent probes for cell imaging; we find that PEGylated FNDs are taken up by HeLa cells and mouse bone marrow-derived dendritic cells and exhibit reduced nonspecific membrane adhesion. Furthermore, we demonstrate functionalization with biotin-PEG-SH and perform long-term high-resolution single-molecule fluorescence based tracking measurements of FNDs tethered via streptavidin to individual biotinylated DNA molecules. Our robust polydopamine encapsulation and functionalization strategy presents a facile route to develop FNDs as multifunctional labels, drug delivery vehicles, and targeting agents for biomedical applications.

Delayed Fluorescence of Dyes Sensitized by Eu3+ Chelate Nanoparticles

Dye-doped nanoparticles of Eu3+ chelate complexes with naphtoyltrifluoroacetone and 1,10-phenanthroline were synthesized using two different reprecipitation techniques. The nanoparticles were characterized by atomic force microscopy, absorption spectroscopy, steady-state, and time-resolved fluorescence spectroscopy. Fluorescent spectroscopy of chelate nanoparticles doped with Oxazine 170 and Nile blue dyes indicates that a single dye molecule efficiently quenches luminescence of more than a hundred chelates. The Eu3+ chelates have a significantly longer luminescence lifetime than organic dyes, which leads to the appearance of delayed dyes fluorescence with microsecond lifetimes. The fluorescence brightness of dye-doped chelate nanoparticles was determined to be 50 times higher than that of a single Rhodamine 6G molecule. The combination of high fluorescence brightness and long fluorescence lifetime of the dye-doped chelate nanoparticles is promising for time-gated applications.

Fluorospectroscopy of Dye-Loaded Liposomes in Photonic Crystal Fibers

The immobilization and probing of liposomes within photonic crystal fibers was demonstrated for the first time. A bioactive surface was used to tether the liposomes. This bioactive surface consisted of streptavidin bound to a photochemically functionalized biotin layer. Bound streptavidin, hence, enabled the further binding of biotinylated dye-loaded liposomes. In-fiber fluorescence spectroscopy was used to quantify the streptavidin coverage density. The same method was also used to characterize the surface-tethered liposomes. The further observation of a unique phenomenon—photobleaching dequenching—was used for the first time as an indication of liposomal content retention. This indicated no rupturing of liposomes, highlighting them as bioderived analogues to dye-doped nanoparticles. The demonstrated integration of liposomes with optical waveguides shows potential as a biointegrated photonic device.

Influence of Surface Plasmon Resonance on Fluorescence Emission of Dye-doped Nanoparticles

The influence of the surface plasmon of gold nanoparticles on the optical properties of the fluorescent nanoparticles in aqueous solution have been investigated. The fluorescence of nanoparticles can be enhanced or quenched in the presence of gold nanoparticles depending on the domination of energy transfer mechanisms: radiating surface plasmon coupling emission or F\"{o}rster energy transfer from fluorescent particles to gold particles, which exciting absorbing plasmon. The fluorescence enhancement or quenching is attributed to the increase or decrease of radiative recombination rates, respectively. The parameters of the energy transfer between fluorescent nanoparticles (dye molecules encapsulated in silica nanoparticles) and nano golds have been estimated. The results show that the interactions between nanoparticles depend on the size of both fluorophores (as donors) and gold nanoparticles (as acceptors).

Mini-review: fluorescence imaging in cancer cells using dye-doped nanoparticles

Fluorescence imaging has gained increased attention over the past two decades as a viable means to detect a variety of cancers.

Membrane-based lateral flow immunochromatographic strip with nanoparticles as reporters for detection: A review.

Membrane-based lateral flow immunochromatographic strip (LFICS) is widely used in various fields because of its simplicity, rapidity (detection within 10min), and low cost. However, early designs of membrane-based LFICS for preliminary screening only provide qualitative ("yes/no" signal) or semi-quantitative results without quantitative information. These designs often suffer from low-signal intensity and poor sensitivity and are only capable of single analyte detection, not simultaneous multiple detections. The performance of existing techniques used for detection using LFICS has been considerably improved by incorporating different kinds of nanoparticles (NPs) as reporters. NPs can serve as alternative labels and improve analytical sensitivity or limit of detection of LFICS because of their unique properties, such as optical absorption, fluorescence spectra, and magnetic properties. The controlled manipulation of NPs allows simultaneous or multiple detections by using membrane-based LFICS. In this review, we discuss how colored (e.g., colloidal gold, carbon, and colloidal selenium NPs), luminescent (e.g., quantum dots, up-converting phosphor NPs, and dye-doped NPs), and magnetic NPs are integrated into membrane-based LFICS for the detection of target analytes. Gold NPs are also featured because of their wide applications. Different types and unique properties of NPs are briefly explained. This review focuses on examples of NP-based LFICS to illustrate novel concepts in various devices with potential applications as screening tools. This review also highlights the superiority of NP-based approaches over existing conventional strategies for clinical analysis, food safety, and environmental monitoring. This paper is concluded by a short section on future research trends regarding NP-based LFICS.

BODIPY-doped silica nanoparticles with reduced dye leakage and enhanced singlet oxygen generation.

Photodynamic therapy (PDT) is a promising modality for cancer treatment. The essential element in PDT is the photosensitizer, which can be excited by light of a specific wavelength to generate cytotoxic oxygen species (ROS) capable of killing tumor cells. The effectiveness of PDT is limited in part by the low yield of ROS from existing photosensitizers and the unwanted side effects induced by the photosensitizers toward normal cells. Thus the design of nanoplatforms with enhanced PDT is highly desirable but remains challenging. Here, we developed a heavy atom (I) containing dipyrromethene boron difluoride (BODIPY) dye with a silylated functional group, which can be covalently incorporated into a silica matrix to form dye-doped nanoparticles. The incorporated heavy atoms can enhance the generation efficiency of ROS. Meanwhile, the covalently dye-encapsulated nanoparticles can significantly reduce dye leakage and subsequently reduce unwanted side effects. The nanoparticles were successfully taken up by various tumor cells and showed salient phototoxicity against these cells upon light irradiation, demonstrating promising applications in PDT. Moreover, the incorporated iodine atom can be replaced by a radiolabeled iodine atom (e.g., I-124, I-125). The resulting nanoparticles will be good contrast agents for positron emission tomography (PET) imaging with their PDT functionality retained.

Multiple Energy Transfer Dynamics in Blended Conjugated Polymer Nanoparticles

Energy transfer dynamics in blended conjugated polymer nanoparticles (CPNs) were investigated in order to further our understanding of photoswitching and anomalous saturation behavior we previously observed, and as a way to probe the complex energy transport processes occurring in similar systems of interest such as nanostructured bulk heterojunction photovoltaic devices. We prepared blended poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadiazole)] (PFBT)/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) nanoparticles with varying blending ratios. Efficient energy transfer from PFBT to MEH-PPV was observed, yielding bright, red-shifted emission. The donor exhibited complex decay kinetics consistent with energy transfer in complex, nanoscale, multichromophoric systems. The fluorescence decay kinetics and steady-state quenching efficiencies are compared to a multiple energy transfer model and prior results for dye-doped nanoparticles. The analysis indicates that the high en...

Förster Resonance Energy Transfer and Laser Efficiency in Colloidal Suspensions of Dye-Doped Nanoparticles: Concentration Effects

The donor and acceptor concentration effects on Förster resonance energy transfer (FRET) and laser properties of polymer nanoparticles (NPs) highly doped with two dyes are comprehensively analyzed. Rhodamine 6G (Rh6G, donor) and Nile Blue (NB, acceptor) are incorporated into anionic methacrylic NPs ∼40 nm in size, in concentrations [Rh6G] = 1–9 mM and [NB] = 0.5–11 mM. The FRET efficiency is mostly influenced by the acceptor concentration due to the presence of more available energy traps and a reduction in the average donor/acceptor distances. We show that the presence of homo-FRET among donors may give rise to an enhancement on the net hetero-FRET efficiency mainly when the concentration of donors exceeds that of the acceptors. When the concentration of both dyes is raised beyond a given value, the FRET efficiency is reduced due to the influence of competing quenching processes. Carefully selected mixtures of Rh6G/NB allow achieving FRET efficiencies as high as 88% and efficient laser emission in which the excitation/pumping light has been fully transferred from Rh6G (∼575 nm) to NB (∼700 nm). Finally, it is shown that, although a higher FRET efficiency does not guarantee higher acceptor laser efficiencies, both are mostly affected by the acceptor concentration and the total amount of dye molecules inside the NPs. This study acquires special relevance since the use of NPs not only allows achieving FRET efficiencies much higher than those attainable in liquid solution (88% vs 57%) but also opens the door to the study of FRET dynamics at concentrations beyond the solubility limit in liquid solutions and without the undesirable effects of reabsorption/re-emission processes (at least for the Rh6G/NB pair).

Photosensitive Fluorescent Dye Contributes to Phototoxicity and Inflammatory Responses of Dye-doped Silica Nanoparticles in Cells and Mice

Dye-doped fluorescent silica nanoparticles provide highly intense and photostable fluorescence signals. However, some dopant dye molecules are photosensitive. A widely-used photosensitive fluorescent dopant, RuBpy, was chosen to systematically investigate the phototoxicity of the dye-doped silica nanoparticles (NPs). We investigated cell viability, DNA damage, and Reactive Oxygen Species (ROS) levels in alveolar macrophages using the dye-doped NPs with or without irradiation. Our results showed that the RuBpy-doped silica NPs could induce significant amount of ROS, DNA damage, apoptosis and impaired proliferation in MH-S cells. In vivo studies in mice showed that RuBpy-doped silica NPs induced significant inflammatory cytokine production and lowered expression in signaling proteins such as ERK1/2 and NF-κB as well as increased lung injury determined by myeloperoxidase and lipid peroxidation. Strikingly, we also found that both RuBpy alone and NPs induced systemic signaling activation in the kidney compared to the liver and lung where showed highly selective signaling patterns, which is more pronounced than RuBpy-doped silica NPs. Moreover, we discovered a critical biomarker (e.g., HMGB1) for silica NPs-induced stress and toxicity and demonstrated differentially-regulated response patterns in various organs. Our results indicate for the first time that the RuBpy-doped silica NPs may impose less inflammatory responses but stronger thermotherapeutic effects on target cells in animals than naked NPs in a time- and dose-dependent manner.