Fluorescent Gold Research Articles

A fluorescent probe based on FRET effect between carbon nanodots and gold nanoparticles for sensitive detection of thiourea

Illegal abuse results in the presence of thiourea (TU) in soil, wastewater, and even fruits, which is harmful for the environment and human health. It has urgent practical significance to design an efficient and reliable probe for TU detection. Herein, a sensitive fluorescent probe with off–on response for harmful TU was reported. The probe was designed with fluorescent carbon nanodots (CNDs) and gold nanoparticles (AuNPs) based on fluorescence resonance energy transfer (FRET) effect. Firstly, the CNDs were pre-combined with AuNPs and the fluorescence of CNDs was quenched due to the FRET effect. Upon addition of TU, the fluorescence of CNDs recovered due to the unbinding of CNDs and AuNPs, since the coordination interaction between TU and AuNPs is stronger than the electrostatic interaction among CNDs and AuNPs. Under the optimum parameters, a linear relationship was found between the relative fluorescence intensity of the probe and the concentration of TU in the range of 5.00 × 10-8-1.00 × 10-6 M (R2 = 0.9958), with the limit of detection (LOD) calculated to be 3.62 × 10-8 M. This proposed method is easy to operate and has excellent selectivity and sensitivity for TU, which can be effectively applied in environmental water and compound fruit-vegetable juice.

Uptake of Functional Ultrasmall Gold Nanoparticles in 3D Gut Cell Models.

Ultrasmall gold nanoparticles (2nm) easily penetrate the membranes of intestinal murine epithelial cells (MODE-K) and colorectal cancer cells (CT-26). They are also taken up by 3D spheroids (400µm) of these cell types and primary gut organoids (500µm). In contrast, dissolved dyes are not taken up by any of these cells or 3D structures. The distribution of fluorescent ultrasmall gold nanoparticles inside cells, spheroids, and gut organoids is examined by confocal laser scanning microscopy. Nanoparticles conjugated with the cytostatic drug doxorubicin and a fluorescent dye exhibit significantly greater cytotoxicity toward CT-26 tumor spheroids than equally concentrated dissolved doxorubicin, probably because they enter the interior of a spheroid much more easily than dissolved doxorubicin. Comprehensive analyses show that the cellular uptake of ultrasmall gold nanoparticles occurs by different endocytosis pathways.

A three-dimensional “turn-on” sensor array for simultaneous discrimination of multiple heavy metal ions based on bovine serum albumin hybridized fluorescent gold nanoclusters

Traditional single sensor is designed based on the “lock-and-key” mode, which only relies on the most dominant interactions between the sensing element and the target. Although it exhibits high selectivity, there are challenges in detecting multiple analytes at the same time. Here, a sensor array with three sensing elements is developed to detect multiple heavy metal ions simultaneously and quickly. In our experiment, bovine serum albumin-encapsulated gold nanoclusters (BSA-AuNCs) were used as fluorescence probes and three different dopamine (DA) concentrations as nonspecific receptors. As we know, self-polymerized polydopamine (PDA) can quench part of the fluorescence of BSA-AuNCs. Upon the addition of the heavy metal ions, the diverse non-specific interactions between DA and heavy metal ions result in the difference in the number of the remaining PDA. Therefore it would lead to different degrees of fluorescence recovery behavior. This unique “turn-on” fluorescence response mode can be analyzed by linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA). Two-dimensional, three-dimensional and even four-dimensional mixed ions detection and quantitative detection have also been achieved. Moreover, by using this fluorescence array mode, heavy metal ions in tap water or blood samples can be detected.

Site‐specific fabrication of gold nanocluster‐based fluorescence photoswitch enabled by the dual roles of albumin proteins

AbstractFluorescence photoswitch is becoming increasingly desirable for many applications, but its controllable fabrication still remains challenging yet. In this paper, a new strategy is proposed to fabricate fluorescence photoswitch by harnessing dual roles of albumin proteins as both photochrome carriers and biotemplates of fluorophore. As an example, we demonstrated the successful fabrication of a fluorescence photoswitch by incorporating both the photochromic diarylethene dye (CMTE) and red‐emitting fluorescent gold nanoclusters (AuNCs) into the specific domains of bovine serum albumin (BSA) in a highly controllable manner. Detailed spectral and photophysical characterisation showed that CMTE well‐retains the photochromic properties within the CMTE–BSA–AuNC construct, although its photoconversion rate is slightly retarded. Different from previously reported photoswitches, the fluorescence of the present system is mainly modulated via the inner filter effect (IFE) mechanism, which exhibits high switching efficiency with an on–off ratio up to 90%, reversible fluorescence response and good antifatigue performance. This work provides a new, generable albumin protein‐assisted strategy of fabricating advanced fluorescence photoswitch, which can find wide applications in biological, optical and information fields.

Multifunctional fluorescent gold nanoclusters with enhanced aggregation-induced emissions (AIEs) and excellent antibacterial effect for bacterial imaging and wound healing.

To explore new alternatives to combat increasing risk of bacterial infection, in this work, a cationic antimicrobial peptide (HHC10) and glutathione (GSH) co-ligand protected ultra-small gold nanoclusters (Au NCs) was constructed by a simple one-pot method. The intrinsic luminescent property of GSH-protected Au NCs (AuxGSH) endowed enhanced aggregation-induced emissions (AIEs) of co-ligand-protected Au NCs (AuxGSH-HHC10), which exhibited a very strong orange luminescence. Based on the AIE effect, for one thing, AuxGSH could be applied to rapidly and selectively detect Gram-positive bacteria. For another, AuxGSH-HHC10 exhibited potential for multicolor imaging of both Gram-negative and Gram-positive bacteria. Besides, as-synthesized AuxGSH-HHC10 could act as potent nanoantibiotics against both Gram-negative and Gram-positive bacteria, which could not only avoid drug tolerance but also be effective toward drug-resistance bacteria. The antibacterial mechanism indicated that the synergetic effect of the generation of reactive oxygen species (ROS), binding with DNA, and broad-spectrum antibacterial activity of HHC10 led to the membrane damage, depolarization, and interference of biological function, thus enhancing the antibacterial effect. More importantly, such an Au NCs could realize excellent therapeutic outcomes for wound healing in vivo, and showed good biocompatibility and biosafety toward health tissues. The results will provide a great potential for the application of Au NCs for imaging-guided antibacterial platform.

A Mouse Model of Endometriosis with Nanoparticle Labeling for In Vivo Photoacoustic Imaging.

Endometriosis is a condition of the female reproductive tract characterized by endometrium-like tissue growing outside the uterus. Though it is a common cause of pelvic pain and infertility, there is currently no reliable noninvasive method to diagnose the presence of endometriosis without surgery, and the pathophysiological mechanisms that lead to the occurrence of symptoms require further inquiry. Due to patient heterogeneity and delayed diagnosis, animal models are commonly used to study the development of endometriosis, but these are costly due to the large number of animals needed to test various treatments and experimental conditions at multiple endpoints. Here, we describe a method for synthesis of multimodal imaging gold-fluorescein isothiocyanate (FITC) nanoparticles with preclinical application via induction of nanoparticle-labeled endometriosis-like lesions in mice. Labeling donor endometrial tissue fragments with gold-FITC nanoparticles prior to induction of endometriosis in recipients enables in vivo detection of the gold-labeled lesions with photoacoustic imaging. The same imaging method can be used to visualize embryos noninvasively in pregnant mice. Furthermore, the conjugated FITC dye on the gold nanoparticles allows easy isolation of labeled lesion tissue under a fluorescence dissection microscope. After dissection, the presence of gold-FITC nanoparticles and endometrium-like histology of lesions can be verified through fluorescence imaging, gold enhancement, and immunostaining. This method for in vivo imaging of endometriosis-like lesions and fluorescence-guided dissection will permit new experimental possibilities for the longitudinal study of endometriosis development and progression as well as endometriosis-related infertility.

Health risk assessment of gaseous elemental mercury (GEM) in Mexico City.

Emissions of gaseous elemental mercury (GEM or Hg0) from different sources in urban areas are important subjects for environmental investigations. In this study, atmospheric Hg measurements were conducted to investigate air pollution in the urban environment by carrying out several mobile surveys in Mexico City. This work presents atmospheric concentrations of GEM in terms of diurnal variation trends and comparisons with criteria for pollutant concentrations such as CO, SO2, NO2, PM2.5, and PM10. The concentration of GEM was measured during the pre-rainy period by using a high-resolution active air sampler, the Lumex RA 915 M mercury analyzer. In comparison with those for other cities worldwide, the GEM concentrations were similar or slightly elevated, and they ranged from 0.20 to 30.23 ng m−3. However, the GEM concentration was significantly lower than those in contaminated areas, such as fluorescent lamp factory locations and gold mining zones. The GEM concentrations recorded in Mexico City did not exceed the WHO atmospheric limit of 200 ng m−3. We performed statistical correlation analysis which suggests equivalent sources between Hg and other atmospheric pollutants, mainly NO2 and SO2, emitted from urban combustion and industrial plants. The atmospheric Hg emissions are basically controlled by sunlight radiation, as well as having a direct relationship with meteorological parameters. The area of the city studied herein is characterized by high traffic density, cement production, and municipal solid waste (MSW) treatment, which constantly release GEM into the atmosphere. In this study, we included the simulation with the HYSPLIT dispersion model from three potential areas of GEM release. Emissions from industrial corridors and volcanic plumes localized outside the urban area contribute to the pollution of Mexico City and mainly affect the northern area during specific periods and climate conditions. Using the USEPA model, we assessed the human health risk resulting from exposure to inhaled GEM among residents of Mexico City. The results of the health risk assessment indicated no significant noncarcinogenic risk (hazard quotient (HQ) < 1) or consequent adverse effects for children and adults living in the sampling area over the study period. GEM emissions inventory data is necessary to improve our knowledge about the Hg contribution and effect in urban megacity areas with the objective to develop public safe policy and implementing the Minamata Convention.Supplementary informationThe online version contains supplementary material available at 10.1007/s10661-022-10107-7.

Engineering light-initiated afterglow lateral flow immunoassay for infectious disease diagnostics

The pandemic of highly contagious diseases has put forward urgent requirements for high sensitivity and adaptive capacity of point-of-care testing (POCT). Herein, for the first time, we report an aggregation-induced emission (AIE) dye-energized light-initiated afterglow nanoprobes (named LiAGNPs), implemented onto a lateral flow immunoassay (LFIA) test strip, for diagnosis of two highly contagious diseases, human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as model validation. The primary working mechanism relies on the cyclically generated singlet oxygen (1O2)-triggered time-resolved luminescent signals of LiAGNPs in which AIE dyes (TTMN) and chemiluminescent substrates (SO) are loaded. The designed LiAGNPs were found 2-fold and 32-fold sensitive than the currently used Eu(III)-based time-resolved fluorescent nanoparticles and gold nanoparticles in lateral flow immunoassay (LFIA), respectively. In addition, the extra optical behaviors of nude color and fluorescence of LiAGNPs enable the LFIA platform with the capability of the naked eye and fluorescent detection to satisfy the applications under varying scenarios. In short, the versatile LiAGNPs have great potential as a novel time-resolved reporter in enhancing detection sensitivity and application flexibility with LFIA platform for rapid but sensitive infectious disease diagnostics.

A novel polypeptide-modified fluorescent gold nanoclusters for copper ion detection

Biomolecule-functionalized fluorescent gold nanocluster (AuNCs) have attracted a lot of attention due to good biocompatibility, stable physicochemical properties and considerable cost advantages. Inappropriate concentration of Cu2+ may cause a variety of diseases. In this study, AuNCs were synthesized in alkaline aqueous solution using bovine serum albumin (BSA) as a template. And then, the peptide CCYWDAHRDY was coupled to AuNCs. Furthermore, the fluorescence of synthesized CCYWDAHRDY-AuNCs response to Cu2+ was evaluated. As the results shown that the CCYWDAHRDY-AuNCs can sensitively detect Cu2+. After adding Cu2+ to the probe system, the fluorescence of the CCYWDAHRDY-AuNCs was quenched. The detection conditions were at pH 6 and 30 °C for 10 min, the linear relationship between Cu2+ concentration and fluorescence intensity were good in the range of 0.1 ~ 4.2 μmol/L. The regression equation was y = − 105.9x + 693.68, the linear correlation coefficient is 0.997, and the minimum detection limit was 52 nmol/L.

Rapid determination of cysteine and chiral discrimination of D-/L-cysteine via the aggregation-induced emission enhancement of gold nanoclusters by Ag.

Cysteine (Cys) plays vital roles in various physiological and pathological functions. Either a deficiency or excess of Cys could lead to severe ailments in human. The identification and determination of Cys are the key issues for the early diagnosis of relevant diseases. This contribution has presented a promising potential of fluorescent gold nanoclusters (AuNCs) for Cys determination and D-/L-Cys enantiomer discrimination. Cys determination and discrimination are involved three steps. First, as a reducing and capping ligand, glutathione was applied to fabricate weak fluorescent AuNCs. Second, Ag+ was introduced to lead the aggregation-induced emission (AIE) to form well-dispersed aggregates. The fluorescence intensity of AuNCs was monitored at excitation/emission wavelengths of 396/620nm. Third, Cys was found to quickly bind with Ag+ to form a grid network to light up the system via aggregation-induced emission enhancement (AIEE). A novel sensor for a sensitive and a visually selective detection of Cys was established on the basis of the AIEE mechanism. Rapid quantitative determination of Cys was achieved in 2min via AIEE within the range of 0.5-100μmol L-1 and a detection limit of 0.365μmol L-1. Moreover, due to the specific interactions of D-/L-Cys with mandelic acid and tartaric acid, the visual discrimination of D-/L-Cys enantiomers with naked eyes was realized by replacing the organic acid buffer.

Regulation of mitophagy by metformin improves the structure and function of retinal ganglion cells following excitotoxicity-induced retinal injury

Excitotoxicity-induced retinal neuronal death is characterized by the progressive retinal ganglion cell (RGC) apoptosis. Strategies are needed to reduce neurodegeneration. Recent investigations have indicated the potential effects of metformin on multiple systems, especially in the networks. However, it also remains unclear whether mitophagy contributes to the neuroprotective effect of metformin on the retina. In this study, excitotoxicity-induced retinal injury models were constructed. In vitro, R28 cells were treated with calcium ionophore and metformin/phosphate-buffer saline (PBS). Cell viability, lactate dehydrogenase release, and the cellular apoptosis rate were assessed. In vivo, rats received intravitreal injection of N-methyl-D-aspartate and metformin/PBS. Comprehensive examinations including retrograde fluorescent gold labelling, Nissl's staining, full-field electroretinography, photopic negative response, optic coherence tomography and retinal imaging, transmission electron microscopy, western blotting, and quantitative polymerase chain reaction were conducted during the observation period. The viability of R28 cells was significantly increased in the metformin-treated group compared with the negative control group, while, the release of lactate dehydrogenase and R28 cell apoptosis showed a significant decrease. In vivo, metformin treatment significantly increased the number of surviving RGCs, the b/NR wave amplitude and the thickness of the inner retina but had no obvious adverse effects on the fundus. In the metformin-treated group, the morphology and number of mitochondria were better preserved, as observed for RGCs; mitochondrial autophagosomes were located in RGCs, as indicated by transmission electron microscopy; and the expression of mitophagy-related genes and proteins presented was significant regulated. These data indicated that the regulation of mitophagy by metformin improved the structure and function of RGCs.

A novel dual-emission fluorescent probe for ratiometric and visual detection of Cu2+ ions and Ag+ ions.

In this work, the biomolecule glutathione was used to prepare cyan fluorescent carbon dots (GSH@CDs) by a hydrothermal method. The GSH@CDs were adopted as the scaffolds to synthesize fluorescent gold nanoclusters (GSH@CDs-Au NCs) with two independent emission peaks at 430nm and 700nm. A fluorescent method for the Cu2+ and Ag+ ion assay was established based on the fluorescence quenching or enhancement at 700nm of GSH@CDs-Au NCs. The fluorescent test strips were successfully prepared for visual detection of Cu2+ ions and Ag+ ions based on GSH@CDs-Au NCs. In addition, GSH@CDs-Au NCs were found to possess well peroxidase-like activity.

The detection of Mercury(II) ions using fluorescent gold nanoclusters on a portable paper-based device

To minimize the need for complex testing procedures, sophisticated instrumentation, and electricity for on-site testing, we demonstrate a simple and portable gold nanocluster (AuNC)-modified paper analytical device integrated with syringe-driven fluid flow to enable highly sensitive mercury ion (Hg2+) detection for environmental monitoring. The device is composed of a paper substrate modified with fluorescent AuNCs (AuNC-paper), which is held within a reusable cartridge connected to a syringe, thus allowing users to flow a large volume of the sample solution through the paper test for greater accumulation of the analyte signal. The metallophilic d10-d10 interaction of Hg2+ with Au+ on the surface of the AuNC-paper induces fluorescence quenching, which can be monitored using a smartphone. Importantly, the red-emitting AuNCs avoid interference with the background fluorescence of the paper substrate. Additionally, the AuNCs are strongly-attached to the paper substrate via carbodiimide coupling, which helps prevent the AuNCs from leaching and enables a large amount of solution to interact with the test (up to 2.5 mL) to increase the amount of the target ions that react with the AuNC-paper. As a result, without the need for preconcentrating the test solution, this paper device can provide the highly sensitive detection of Hg2+ ions, including a 26-fold higher sensitivity than the AuNC-modified test paper without a fluidic cartridge, at a low level of down to nM. The paper platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM, which is less than the United States Environmental Protection Agency’s regulatory limit for drinking water. This highly sensitive, selective, portable, and easy-to-operate platform may be valuable for on-site mercury pollution monitoring in resource-constrained settings.

Controlling the Interaction between Fluorescent Gold Nanoclusters and Biointerfaces for Rapid Discrimination of Fungal Pathogens.

Nondestructive detection and discrimination of fungal pathogens is essential for rapid and precise treatment, which further effectively prevents antifungal resistance from overused drugs. In this work, fluorescent gold nanoclusters served as the basis for discriminating Candida species. Varied on surface ligands, these gold nanoclusters demonstrated different optical properties as a result of the perturbation effects of ligands. The biointerface interaction between the surface ligands of gold nanoclusters and the cell walls of Candida species can be constructed, and their restriction on ligands perturbation effect produced enhanced fluorescence signals. Owing to the variation of the cell wall composition, cells of different Candida species demonstrated different degrees of association with the gold nanoclusters, leading to discriminable amounts of fluorescence enhancements. The reverse signal response from these gold nanoclusters gives rise to a synergistic and effective assay that allows identification of Candida species.

Excellent Multiphoton Excitation Fluorescence with Large Multiphoton Absorption Cross Sections of Arginine-Modified Gold Nanoclusters for Bioimaging.

Fluorescent gold nanoclusters (Au NCs) with excellent one-photon and multiphoton properties have been demonstrated as promising candidates in many application fields. However, small multiphoton absorption (MPA) cross sections and weak multiphoton excitation (MPE) fluorescence impede their practical applications under near-infrared (NIR) excitation for biological imaging. Here, we report the regulated one-photon and multiphoton properties and mechanisms of arginine-stabilized 6-aza-2-thiothymine Au NCs (Arg/ATT-Au NCs) and the applications for MPE fluorescence imaging. The introduction of arginine into the capping layer of ATT-Au NCs significantly modifies the electronic structure, the absorption cross sections, and the relaxation dynamics of the lowest excited state, drastically reducing the nonradiative relaxation, suppressing the blinking, and greatly enhancing the fluorescence. Besides the improved one-photon properties, Arg/ATT-Au NCs demonstrate remarkable MPE fluorescence with a large MPA cross section. The two-photon (λex = 850 nm), three-photon (λex = 1400 nm), and four-photon (λex = 1700 nm) absorption cross sections have been determined to be 6.1 × 10-47 cm4 s1 photon-1, 1.5 × 10-78 cm6 s2 photon-2, and 5.5 × 10-108 cm8 s3 photon-3, respectively, much higher than those of conventional organic compounds and previously reported Au NCs. Moreover, Arg/ATT-Au NCs have been successfully applied in two-photon and three-photon excitation fluorescence imaging of living cells with NIR excitation. The manifold advantages of small size, high quantum yield, suppressed blinking, good photostability and cytocompatibility, large MPA cross sections, and excellent MPE fluorescence imaging performances make fluorescent Arg/ATT-Au NCs a great candidate of imaging probes with vis-NIR excitation.

Fluorescent polymer-modified gold nanobipyramids for temperature sensing during photothermal therapy in living cells

The temperature monitoring of treated cancer cells is critical in photothermal therapy. Current methods of detecting intracellular temperatures have low accuracy and poor spatial resolution, which limits their application to photothermal therapy. Herein, a strategy for targeted recognition and selective capture of MCF-7 breast cancer cells based on fluorescent polymer poly(N-isopropylacrylamide-benzoxadiazole-2-vinyl-4,4-dimethyl azlactone, PNMV) and modified gold nanobipyramids (AuNBPs-PNMV) was developed for temperature sensing during photothermal therapy. A mucin-1 protein aptamer (Apt) was applied to selectively target mucin-1 protein overexpressed on the surfaces of the MCF-7 cells, which can reduce interference by affinity interaction between the Apt and proteins. During photothermal therapy, the significant AuNBPs photothermal effect increases the fluorescence intensity of PNMV with temperature. Irradiation of MCF-7 cells cultured with AuNBPs-PNMV@Apt by an 808 nm laser increases the temperature of the system, while the cells can be inactivated because of the remarkable AuNBPs-PNMV@Apt photothermal effect. The results indicate that variation in the fluorescence of AuNBPs-PNMV@Apt can be applied as thermometers to monitor the intracellular effect of photothermal therapy.

Advances in biological imaging applications of fluorescent gold nanoclusters (invited)

Advances in biological imaging applications of fluorescent gold nanoclusters (invited)

Highly luminescent gold nanocluster assemblies for bioimaging in living organisms.

Fluorescent gold nanoclusters are promising nanomaterials for biomedical applications but confronted with low emission efficiency and poor surface functionality. Herein, three kinds of highly luminescent and functionalized gold nanocluster nano-assembled structures were fabricated by poly-l-arginine surface engineering for luminescence improvement. The assembly is employed for imaging the glutathione molecule in cells and living organisms with low background and high sensitivity.

Bioconjugation of Fluorescent Gold Nanoparticles Synthesized Using Marine Brown Algae Sargassum longifolium

In the present study, fluorescent gold nanoparticles (Flu Au‐NPs) were synthesized via simple and ecofriendly green route using extract of brown algae Sargassum longifolium (S. longifolium). Characterization of synthesized Au‐NPs was undertaken. The characteristic absorption peak of Au‐NPs was in range 530 nm in UV‐vis spectrum. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allow the visualization of the morphological and structural character of Au‐NPs. The mean particle size was calculated to be 17‐50 nm. Energy dispersive X‐ray spectroscopy analysis (EDAX) confirmed the presence of pure gold in the synthesized Au‐NPs. The X‐ray diffraction (XRD) pattern showed the face‐centered cubic (FCC) nature of Au‐NPs. Fourier transform infrared spectrometer (FT‐IR) showed the characteristic peaks of different biocomponents in the brown algae S. longifolium extract which acted as stabilizing or capping agents of Au‐NPs.

A plasmon-enhanced fluorescent gold coated novel lipo-polymeric hybrid nanosystem: synthesis, characterization and application for imaging and photothermal therapy of breast cancer.

This study reports a hybrid lipo-polymeric nanosystem (PDPC NPs) synthesized by a modified hydrogel-isolation technique. The ability of the nanosystem to encapsulate hydrophilic and hydrophobic molecules has been demonstrated, and their enhanced cellular uptake has been observed in vitro. The PDPC NPs, surface coated with gold by in situ reduction of chloroauric acid (PDPC-Au NPs), showed a photothermal transduction efficacy of ∼65%. The PDPC-Au NPs demonstrated an increase in intracellular ROS, triggered DNA damage and resulted in apoptotic cell death when tested against breast cancer cells (MCF-7). The disintegration of PDPC-Au NPs into smaller nanoparticles with near-infrared (NIR) laser irradiation was understood using transmission electron microscopy imaging. The lipo-polymeric hybrid nanosystem exhibited plasmon-enhanced fluorescence when loaded with IR780 (a NIR dye), followed by surface coating with gold (PDPC-IR-Au NPs). This paper is one of the first reports on the plasmon-enhanced fluorescence within a nanosystem by simple surface coating of Au, to the best of our knowledge. This plasmon-enhanced fluorescence was unique to the lipo-polymeric hybrid system, as the same was not observed with a liposomal nanosystem. The plasmon-enhanced fluorescence of PDPC-IR-Au NPs, when applied for imaging cancer cells and zebrafish embryos, showed a strong fluorescence signal at minimal concentrations of the dye. The PDPC-IR-Au NPs were also applied for photothermal therapy of breast cancer in vitro and in vivo, and the results depicted significant therapeutic benefits.