Enhanced tumor treatment using biofunctional indocyanine green-containing nanostructure by intratumoral or intravenous injection

Erythrocyte membrane is an alternative coating to polyethylene glycol for prolonging the circulation lifetime of gold nanocages for photothermal therapy

Gold nanocages (AuNCs), which have tunable near-infrared (NIR) absorption and intrinsically high photothermal conversion efficiency, have been actively investigated as photothermal conversion agents for photothermal therapy (PTT). The short blood circulation lifetime of AuNCs, however, limits their tumor uptake and thus in vivo applications. Here we show that such a limitation can be overcome by cloaking AuNCs with red blood cell (RBC) membranes, a natural stealth coating. The fusion of RBC membranes over AuNC surface does not alter the unique porous and hollow structures of AuNCs, and the resulting RBC-membrane-coated AuNCs (RBC-AuNCs) exhibit good colloidal stability. Upon NIR laser irradiation, the RBC-AuNCs demonstrate in vitro photothermal effects and selectively ablate cancerous cells within the irradiation zone as do the pristine biopolymer-stealth-coated AuNCs. Moreover, the RBC-AuNCs exhibit significantly enhanced in vivo blood retention and circulation lifetime compared to the biopolymer-stealth-coated counterparts, as demonstrated using a mouse model. With integrated advantages of photothermal effects from AuNCs and long blood circulation lifetime from RBCs, the RBC-AuNCs demonstrate drastically enhanced tumor uptake when administered systematically, and mice that received PPT cancer treatment modulated by RBC-AuNCs achieve 100% survival over a span of 45 days. Taken together, our results indicate that the long circulating RBC-AuNCs may facilitate the in vivo applications of AuNCs, and the RBC-membrane stealth coating technique may pave the way to improved efficacy of PPT modulated by noble metal nanoparticles.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

India ink incorporated multifunctional phase-transition nanodroplets for photoacoustic/ultrasound dual-modality imaging and photoacoustic effect based tumor therapy

The in vivo applications of gas-core microbubbles have been limited by gas diffusion, rapid body clearance, and poor vascular permeability. To overcome these limitations, using a modified three-step emulsion process, we have developed a first-of-its-kind India ink incorporated optically-triggerable phase-transition perfluorocarbon nanodroplets (INDs) that can provide not only three types of contrast mechanisms—conventional/thermoelastic photoacoustic, phase-transition/nonlinear photoacoustic, and ultrasound imaging contrasts, but also a new avenue for photoacoustic effect mediated tumor therapy. Upon pulsed laser illumination above a relatively low energy threshold, liquid-gas phase transition of the INDs has been demonstrated both in vitro and in vivo, offering excellent contrasts for photoacoustic and ultrasound dual-modality imaging. With further increased laser energy, the nanodroplets have been shown to be capable of destructing cancer cells in vivo, presumably due to the photoacoustic effect induced shock-wave generation from the carbon particles of the incorporated India ink. The demonstrated results suggest that the developed multifunctional phase-transition nanodroplets have a great potential for many theranostic biomedical applications, including photoacoustic/ultrasound dual-modality molecular imaging and targeted, localized cancer therapy.

Robust ICG theranostic nanoparticles for folate targeted cancer imaging and highly effective photothermal therapy

Folic acid (FA)-targeted indocyanine green (ICG)-loaded nanoparticles (NPs) (FA-INPs) were developed to a near-infrared (NIR) fluorescence theranostic nanoprobe for targeted imaging and photothermal therapy of cancer. The FA-INPs with good monodispersity exhibited excellent size and fluorescence stability, preferable temperature response under laser irradiation, and specific molecular targeting to MCF-7 cells with FA receptor overexpression, compared to free ICG. The FA-INPs enabled NIR fluorescence imaging to in situ monitor the tumor accumulation of the ICG. The cell survival rate assays in vitro and photothermal therapy treatments in vivo indicated that FA-INPs could efficiently targeted and suppressed MCF-7 cells and xenograft tumors. Hence, the FA-INPs are notable theranostic NPs for imaging-guided cancer therapy in clinical application.

Improving drug accumulation and photothermal efficacy in tumor depending on size of ICG loaded lipid-polymer nanoparticles

A key challenge to strengthen anti-tumor efficacy is to improve drug accumulation in tumors through size control. To explore the biodistribution and tumor accumulation of nanoparticles, we developed indocyanine green (ICG) loaded poly (lactic-co-glycolic acid) (PLGA) -lecithin-polyethylene glycol (PEG) core-shell nanoparticles (INPs) with 39 nm, 68 nm and 116 nm via single-step nanoprecipitation. These INPs exhibited good monodispersity, excellent fluorescence and size stability, and enhanced temperature response after laser irradiation. Through cell uptake and photothermal efficiency in vitro, we demonstrated that 39 nm INPs were more easily be absorbed by pancreatic carcinoma tumor cells (BxPC-3) and showed better photothermal damage than that of 68 nm and 116 nm size of INPs. Simultaneously, the fluorescence of INPs offered a real-time imaging monitor for subcellular locating and in vivo metabolic distribution. Near-infrared imaging in vivo and photothermal therapy illustrated that 68 nm INPs showed the strongest efficiency to suppress tumor growth due to abundant accumulation in BxPC-3 xenograft tumor model. The findings revealed that a nontoxic, size-dependent, theranostic INPs model was built for in vivo cancer imaging and photothermal therapy without adverse effect.

Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells

Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 10(7) M(-1) cm(-1)), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm(-2), 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm(-2). These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.

Photodynamic therapeutic role of indocyanine green in tumor-associated inflammation in skin cancer

BACKGROUND

Indocyanine green (ICG) is a promising water-soluble photosensitizer for photodynamic therapy (PDT) of tumors. It was reported to have promising phototoxic effect on different cell lines. This study aimed to evaluate the efficacy of ICG as an efficient PS agent for skin cancer induced in mice.

METHODS

Skin squamous cell carcinoma was induced in female CD-1 mice by 7,12-dimethylbenzanthracene and 12-O-tetradecanoyl-phorbol-13-acetate followed by an ICG/PDT treatment. The laser irradiation for PDT was adjusted to cover the whole body of the mice to make sure that the treatment protocol will be delivered to multiple tumors.

RESULTS

The treatment of skin cancer by ICG/PDT using intravenously injected ICG initiated tumor cell death and significantly decreased cell proliferation as indicated by the reduction in proliferating cell nuclear antigen positivity. A significant reduction in the inflammatory mediators; tumor necrosis factor-α, nitric oxide and 5-lipoxygenase was reported, however the level of cyclooxygenase-2 (COX-2) was significantly elevated after ICG/PDT treatment.

CONCLUSION

The proposed ICG/PDT treatment modality showed a significant anti-tumor and anti-inflammatory activity against skin cancer accompanied with COX-2 elevation.

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

Near-infrared fluorescence (NIRF) imaging is an attractive modality for early cancer detection with high sensitivity and multi-detection capability. Due to convenient modification by conjugating with moieties of interests, NIRF probes are ideal candidates for cancer targeted imaging. Additionally, the combinatory application of NIRF imaging and other imaging modalities that can delineate anatomical structures extends fluorometric determination of biomedical information. Moreover, nanoparticles loaded with NIRF dyes and anticancer agents contribute to the synergistic management of cancer, which integrates the advantage of imaging and therapeutic functions to achieve the ultimate goal of simultaneous diagnosis and treatment. Appropriate probe design with targeting moieties can retain the original properties of NIRF and pharmacokinetics. In recent years, great efforts have been made to develop new NIRF probes with better photostability and strong fluorescence emission, leading to the discovery of numerous novel NIRF probes with fine photophysical properties. Some of these probes exhibit tumoricidal activities upon light radiation, which holds great promise in photothermal therapy, photodynamic therapy, and photoimmunotherapy. This review aims to provide a timely and concise update on emerging NIRF dyes and multifunctional agents. Their potential uses as agents for cancer specific imaging, lymph node mapping, and therapeutics are included. Recent advances of NIRF dyes in clinical use are also summarized.

Facile and green reduction of covalently PEGylated nanographene oxide via a 'water-only' route for high-efficiency photothermal therapy

A facile and green strategy is reported for the fabrication of nanosized and reduced covalently PEGylated graphene oxide (nrGO-PEG) with great biocompatibility and high near-infrared (NIR) absorbance. Covalently PEGylated nGO (nGO-PEG) was synthesized by the reaction of nGO-COOH and methoxypolyethylene glycol amine (mPEG-NH2). The neutral and purified nGO-PEG solution was then directly bathed in water at 90°C for 24 h without any additive to obtain nrGO-PEG. Covalent PEGylation not only prevented the aggregation of nGO but also dramatically promoted the reduction extent of nGO during this reduction process. The resulting single-layered nrGO-PEG sheets were approximately 50 nm in average lateral dimension and exhibited great biocompatibility and approximately 7.6-fold increment in NIR absorption. Moreover, this facile reduction process repaired the aromatic structure of GO. CCK-8 and flow cytometry (FCM) assays showed that exposure of A549 cells to 100 μg/mL of nrGO-PEG for 2 h, exhibiting 71.5% of uptake ratio, did not induce significant cytotoxicity. However, after irradiation with 808 nm laser (0.6 W/cm2) for 5 min, the cells incubated with 6 μg/mL of nrGO-PEG solution showed approximately 90% decrease of cell viability, demonstrating the high-efficiency photothermal therapy of nrGO-PEG to tumor cells in vitro. This work established nrGO-PEG as a promising photothermal agent due to its small size, great biocompatibility, high photothermal efficiency, and low cost.

Self-assembly-induced near-infrared fluorescent nanoprobes for effective tumor molecular imaging

Self-assembly-induced near-infrared fluorescent nanoprobes exhibiting spontaneous lattices were prepared and evaluated for in vitro and in vivo tumor molecular imaging.

Synergistic dual-targeting hydrogel improves targeting and anticancer effect of Taxol in vitro and in vivo

A synergistic dual-targeting self-assembly hydrogel was designed with estrone and RGD to enhance targeted delivery and anticancer effect of Taxol.

Intratumoral gene therapy versus intravenous gene therapy for distant metastasis control with 2-diethylaminoethyl-dextran methyl methacrylate copolymer non-viral vector-p53

Lung cancer still remains to be challenged by novel treatment modalities. Novel locally targeted routes of administration are a methodology to enhance treatment and reduce side effects. Intratumoral gene therapy is a method for local treatment and could be used either in early-stage lung cancer before surgery or at advanced stages as palliative care. Novel non-viral vectors are also in demand for efficient gene transfection to target local cancer tissue and at the same time protect the normal tissue. In the current study, C57BL/6 mice were divided into three groups: (a) control, (b) intravenous and (c) intatumoral gene therapy. The novel 2-Diethylaminoethyl-Dextran Methyl Methacrylate Copolymer Non-Viral Vector (Ryujyu Science Corporation) was conjugated with plasmid pSicop53 from the company Addgene for the first time. The aim of the study was to evaluate the safety and efficacy of targeted gene therapy in a Lewis lung cancer model. Indeed, although the pharmacokinetics of the different administration modalities differs, the intratumoral administration presented increased survival and decreased distant metastasis. Intratumoral gene therapy could be considered as an efficient local therapy for lung cancer.

Exclusive photothermal heat generation by a gadolinium bis(naphthalocyanine) complex and inclusion into modified high-density lipoprotein nanocarriers for therapeutic applications

A hydrophobic gadolinium bis(naphthalocyanine) sandwich complex (GdSand) possessing several absorbances across visible and infrared wavelengths (up to 2500 nm) was solubilized in aqueous solution by uptake into a nascent mutant high-density lipoprotein (HDL) nanocarrier. The HDL nanocarrier was additionally functionalized with a trans-activator of transcription peptide sequence to promote efficient cell penetration of the drug delivery system (cpHDL). The dye-loaded nanocarrier (GdSand@cpHDL) exhibited photothermal heat generation properties upon irradiation with near-infrared (NIR) laser light, with controllable heat generation abilities as a function of the incident laser light power. Comparison of the photothermal behavior of the dyes GdSand and the well-explored molecular photothermal agent indocyanine green (ICG) in the cpHDL nanocarrier (i.e., ICG@cpHDL) revealed two significant advantages of GdSand@cpHDL: (1) the ability to maintain elevated temperatures upon light absorption for extended periods of time, with a reduced degree of self-destruction of the dye, and (2) exclusive photothermal heat generation with no detectable singlet oxygen production leading to improved integrity of the cpHDL nanocarrier after irradiation. Finally, GdSand@cpHDL was successfully subjected to an in vitro study against NCI-H460 human lung cancer cells, demonstrating the proof-of-principle utility of lanthanide sandwich complexes in photothermal therapeutic applications.

REVIEW OF METAL, CARBON AND POLYMER NANOPARTICLES FOR INFRARED PHOTOTHERMAL THERAPY

The aim of this review is to provide an up-to-date overview of nanoparticles developed for use as photothermal therapy agents (PTT) over the past five years. The main emphasis is on nanoparticles that absorb near infrared (NIR) light for PTT of cancer. Mild hyperthermia, including drug delivery, versus thermal ablation is also discussed. Recent advances in the synthesis of highly anisotropic novel metal nanoparticles for PTT are described. New metals and metal oxide complexes, as well as the use of quantum dots for PTT and as imaging agents are newer areas of development that are explained. This review also highlights current progress in the development of carbon nanoparticles, including reduced graphene oxide for both thermal ablation as well as drug delivery. The review culminates in the recent use electrically conductive polymer nanoparticles for hyperthermia. The advantages and unique features of these contemporary nanoparticles being used for PTT are highlighted. The goal of the present work is to describe the recent evolution of nanoparticles for NIR stimulated PTT, and highlight the innovations and future directions.

Intratumoral chemotherapy for lung cancer: re-challenge current targeted therapies

Strategies to enhance the already established doublet chemotherapy regimen for lung cancer have been investigated for more than 20 years. Initially, the concept was to administer chemotherapy drugs locally to the tumor site for efficient diffusion through passive transport within the tumor. Recent advances have enhanced the diffusion of pharmaceuticals through active transport by using pharmaceuticals designed to target the genome of tumors. In the present study, five patients with non-small cell lung cancer epidermal growth factor receptor (EGFR) negative stage IIIa–IV International Union Against Cancer 7 (UICC-7), and with Eastern Cooperative Oncology Group (ECOG) 2 scores were administered platinum-based doublet chemotherapy using combined intratumoral-regional and intravenous route of administration. Cisplatin analogues were injected at 0.5%–1% concentration within the tumor lesion and proven malignant lymph nodes according to pretreatment histological/cytological results and the concentration of systemic infusion was decreased to 70% of a standard protocol. This combined intravenous plus intratumoral-regional chemotherapy is used as a first line therapy on this short series of patients. To the best of our knowledge this is the first report of direct treatment of involved lymph nodes with cisplatin by endobronchial ultrasound drug delivery with a needle without any adverse effects. The initial overall survival and local response are suggestive of a better efficacy compared to established doublet cisplatin–based systemic chemotherapy in (higher) standard concentrations alone according to the UICC 7 database expected survival. An extensive search of the literature was performed to gather information of previously published literature of intratumoral chemo-drug administration and formulation for this treatment modality. Our study shows a favorable local response, more than a 50% reduction, for a massive tumor mass after administration of five sessions of intratumoral chemotherapy plus two cycles of low-dose intravenous chemotherapy according to our protocol. These encouraging results (even in very sick ECOG 2 patients with central obstructive non-small cell lung cancer having a worse prognosis and quality of life than a non-small cell lung cancer in ECOG 0 of the same tumor node metastasis [TNM]-stage without central obstruction) for a chemotherapy-only protocol that differs from conventional cisplatin-based doublet chemotherapy by the route, target site, and dose paves the way for broader applications of this technique. Finally, future perspectives of this treatment and pharmaceutical design for intratumoral administration are presented.

In vivo photoacoustic therapy with cancer-targeted indocyanine green-containing nanoparticles

Aim: The objective of this work was to study the photoacoustic effect of a special nanoparticle for selective cancer cell killing both in vitro and in vivo. Materials & methods: The nanoparticles (NPs) consisting of indocyanine green (ICG), phospholipid–polyethylene glycol (PL–PEG) and folic acid (FA) were used as cancer-targeting nanoprobes. Cancer cells incubated with the ICG–PL–PEG–FA solution were exposed to laser pulses. Finally, tumors in mice were treated with photoacoustic technique. Results: High selectivity of the photoacoustic destruction of cancer cells was observed. The tumors in mice after photoacoustic treatment showed a much slower growth rate. Conclusion: The destruction of the cells was due to the photoacoustic effect originating from the NPs. The ICG–PL–PEG NP-based photoacoustic therapy would be a safe and highly efficient cancer treatment technique.

Original submitted 21 February 2012; Revised submitted 2 August 2012; Published online 10 September 2012

Single-step assembly of DOX/ICG loaded lipid--polymer nanoparticles for highly effective chemo-photothermal combination therapy

A combination of chemotherapy and photothermal therapy has emerged as a promising strategy for cancer therapy. To ensure the chemotherapeutic drug and photothermal agent could be simultaneously delivered to a tumor region to exert their synergistic effect, a safe and efficient delivery system is highly desirable. Herein, we fabricated doxorubicin (DOX) and indocyanine green (ICG) loaded poly(lactic-co-glycolic acid) (PLGA)-lecithin-polyethylene glycol (PEG) nanoparticles (DINPs) using a single-step sonication method. The DINPs exhibited good monodispersity, excellent fluorescence/size stability, and consistent spectra characteristics compared with free ICG or DOX. Moreover, the DINPs showed higher temperature response, faster DOX release under laser irradiation, and longer retention time in tumor. In the meantime, the fluorescence of DOX and ICG in DINPs was also visualized for the process of subcellular location in vitro and metabolic distribution in vivo. In comparison with chemo or photothermal treatment alone, the combined treatment of DINPs with laser irradiation synergistically induced the apoptosis and death of DOX-sensitive MCF-7 and DOX-resistant MCF-7/ADR cells, and suppressed MCF-7 and MCF-7/ADR tumor growth in vivo. Notably, no tumor recurrence was observed after only a single dose of DINPs with laser irradiation. Hence, the well-defined DINPs exhibited great potential in targeting cancer imaging and chemo-photothermal therapy.

Comparison study of gold nanohexapods, nanorods, and nanocages for photothermal cancer treatment

Gold nanohexapods represent a novel class of optically tunable nanostructures consisting of an octahedral core and six arms grown on its vertices. By controlling the length of the arms, their localized surface plasmon resonance peaks could be tuned from the visible to the near-infrared region for deep penetration of light into soft tissues. Herein we compare the in vitro and in vivo capabilities of Au nanohexapods as photothermal transducers for theranostic applications by benchmarking against those of Au nanorods and nanocages. While all these Au nanostructures could absorb and convert near-infrared light into heat, Au nanohexapods exhibited the highest cellular uptake and the lowest cytotoxicity in vitro for both the as-prepared and PEGylated nanostructures. In vivo pharmacokinetic studies showed that the PEGylated Au nanohexapods had significant blood circulation and tumor accumulation in a mouse breast cancer model. Following photothermal treatment, substantial heat was produced in situ and the tumor metabolism was greatly reduced for all these Au nanostructures, as determined with (18)F-flourodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT). Combined together, we can conclude that Au nanohexapods are promising candidates for cancer theranostics in terms of both photothermal destruction and contrast-enhanced diagnosis.

Nanomaterials for photo-based diagnostic and therapeutic applications

Photo-based diagnosis and treatment methods are gaining prominence due to increased spatial imaging resolution, minimally invasive modalities involved as well as localized treatment. Recently, nanoparticles (NPs) have been developed and used in photo-based therapeutic applications. While some nanomaterials have inherent photo-based imaging capabilities, others including polymeric NPs act as nanocarriers to deliver various fluorescent dyes or photosensitizers for photoimaging and therapeutic applications. These applications can vary from Magnetic Resonance Imaging (MRI) and optical imaging to photothermal therapy (PTT) and chemotherapy. Materials commonly used for development of photo-based NPs ranges from metal-based (gold, silver and silica) to polymer-based (chitosan, dextran, poly ethylene glycol (PEG) and poly lactic-co-glycolic acid (PLGA)). Recent research has paved the way for multi-modal 'theranostic' (a combination of therapy and diagnosis) nano-carriers capable of active targeting using cell-specific ligands and carrying multiple therapeutic and imaging agents for accurate diagnosis and controlled drug delivery. This review summarizes the different materials used today to synthesize photo-based NPs, their diagnostic and therapeutic applications as well as the current challenges faced in bringing these novel nano-carriers into clinical practices.

Application of near-infrared dyes for tumor imaging, photothermal, and photodynamic therapies

Near-infrared (NIR) dyes, small organic molecules that function in the NIR region, have received increasing attention in recent years as diagnostic and therapeutic agents in the field of tumor research. They have been demonstrated great successes in imaging and treating tumors both in vitro and in vivo. And their different applications in clinical practices have made rapid gains. This review primarily focuses on the progress of the application of NIR dyes in tumor imaging and therapy. In particular, advances in the use of different NIR dyes in tumor-specific imaging, photothermal, and photodynamic therapies are discussed. Limitations and prospects associated with NIR dyes in diagnostic and therapeutic application are also reviewed.

Target-specific nanoparticles containing a broad band emissive NIR dye for the sensitive detection and characterization of tumor development

Current optical probes including engineered nanoparticles (NPs) are constructed from near infrared (NIR)-emissive organic dyes with narrow absorption and emission bands and small Stokes shifts prone to aggregation-induced self-quenching. Here, we present the new asymmetric cyanine Itrybe with broad, almost environment-insensitive absorption and emission bands in the diagnostic window, offering a unique flexibility of the choice of excitation and detection wavelengths compared to common NIR dyes. This strongly emissive dye was spectroscopically studied in different solvents and encapsulated into differently sized (15, 25, 100 nm) amino-modified polystyrene NPs (PSNPs) via a one-step staining procedure. As proof-of-concept for its potential for pre-/clinical imaging applications, Itrybe-loaded NPs were surface-functionalized with polyethylene glycol (PEG) and the tumor-targeting antibody Herceptin and their binding specificity to the tumor-specific biomarker HER2 was systematically assessed. Itrybe-loaded NPs display strong fluorescence signals in vitro and in vivo and Herceptin-conjugated NPs bind specifically to HER2 as demonstrated in immunoassays as well as on tumor cells and sections from mouse tumor xenografts in vitro. This demonstrates that our design strategy exploiting broad band-absorbing and -emitting dyes yields versatile and bright NIR probes with a high potential for e.g. the sensitive detection and characterization of tumor development and progression.