Fast clearing RGD-based near-infrared fluorescent probes for in vivo tumor diagnosis

Introducing Specific Iodine Ions in Perovskite-Based Nanocomplex to Cater for Versatile Biomedical Imaging and Tumor Radiotherapy

Multimodal biomedical imaging and imaging-guided therapy have garnered extensive attention owing to the aid of nanoagents with the aim of further improving the therapeutic efficacy of diseases. The ability to engineer nanocomplexes (NCs) or control how they behave within an organism remains largely elusive. Here, a multifunctional nanoplatform is developed based on stabilized I-doped perovskite, CsPbBr3 -x Ix @SiO2 @Lip-c(RGD)2 (PSL-c(RGD)2 ) NCs. In particular, by regulating the amount of regular I- ions introduced, the fluorescence emission spectrum of perovskite-based NCs can be modulated well to match the requirement for biomedical optical imaging at the scale from molecule, cell to mouse; doping 125 I enables the nanoformulation to be competent for single-photon emission computed tomography (SPECT) imaging; the introduction of 131 I- imparts the NCs with the capability for radiotherapy. Through facile manipulation of specific iodine ions, this nanoplatform exhibits a remarkable ability to match multifunctional biomedical imaging and tumor therapy. In addition, their in vivo behavior can be manipulated by adjusting the thickness of the silica shell and the surface polarity for more practical applications. These experimental explorations offer a novel approach for engineering desirable multimodal NCs to simultaneously image and combat malignant tumors.

Targeting the Oxytocin Receptor for Breast Cancer Management: A Niche for Peptide Tracers

Breast cancer is a leading cause of death in women, and its management highly depends on early disease diagnosis and monitoring. This remains challenging due to breast cancer's heterogeneity and a scarcity of specific biomarkers that could predict responses to therapy and enable personalized treatment. This Perspective describes the diagnostic landscape for breast cancer management, molecular strategies targeting receptors overexpressed in tumors, the theranostic potential of the oxytocin receptor (OTR) as an emerging breast cancer target, and the development of OTR-specific optical and nuclear tracers to study, visualize, and treat tumors. A special focus is on the chemistry and pharmacology underpinning OTR tracer development, preclinical in vitro and in vivo studies, challenges, and future directions. The use of peptide-based tracers targeting upregulated receptors in cancer is a highly promising strategy complementing current diagnostics and therapies and providing new opportunities to improve cancer management and patient survival.

Emerging trends of receptor-mediated tumor targeting peptides: A review with perspective from molecular imaging modalities

Natural peptides extracted from natural components such are known to have a relatively short in-vivo half-life and can readily metabolize by endo- and exo-peptidases. Fortunately, synthetic peptides can be easily manipulated to increase in-vivo stability, membrane permeability and target specificity with some well-known natural families. Many natural as well as synthetic peptides target to their endogenous receptors for diagnosis and therapeutic applications. In order to detect these peptides externally, they must be modified with radionuclides compatible with single photon emission computed tomography (SPECT) or positron emission tomography (PET). Although, these techniques mainly rely on physiological changes and have profound diagnostic strength over anatomical modalities such as MRI and CT. However, both SPECT and PET observed to possess lack of anatomical reference frame which is a key weakness of these techniques, and unfortunately, cannot be available freely in most clinical centres especially in under-developing countries. Hence, it is need of the time to design and develop economic, patient friendly and versatile strategies to grapple with existing problems without any hazardous side effects. Optical molecular imaging (OMI) has emerged as a novel technique in field of medical science using fluorescent probes as imaging modality and has ability to couple with organic drugs, small molecules, chemotherapeutics, DNA, RNA, anticancer peptide and protein without adding chelators as necessary for radionuclides. Furthermore, this review focuses on difference in imaging modalities and provides ample knowledge about reliable, economic and patient friendly optical imaging technique rather radionuclide-based imaging techniques.

Smart Self-Assembly Amphiphilic Cyclopeptide-Dye for Near-Infrared Window-II Imaging

Development of novel nanomaterials for disease theranostics represents an important direction in chemistry and precision medicine. Fluorescent molecular probes in the second near-infrared window (NIR-II, 1000-1700 nm) show high promise because of their exceptional high detection sensitivity, resolution, and deep imaging depth. Here, a sharp pH-sensitive self-assembling cyclopeptide-dye, SIMM1000, as a smart nanoprobe for NIR-II imaging of diseases in living animals, is reported. This small molecule assembled nanoprobe exhibits smart properties by responding to a sharp decrease of pH in the tumor microenvironment (pH 7.0 to 6.8), aggregating from small nanoprobe (80 nm at pH 7.0) into large nanoparticles (>500 nm at pH 6.8) with ≈20-30 times enhanced fluorescence compared with the non-self-assembled CH-4T. It yields micrometer-scale resolution in blood vessel imaging and high contrast and resolution in bone and tumor imaging in mice. Because of its self-aggregation in acidic tumor microenvironments in situ, SIMM1000 exhibits high tumor accumulation and extremely long tumor retention (>19 days), while being excretable from normal tissues and safe. This smart self-assembling small molecule strategy can shift the paradigm of designing new nanomaterials for molecular imaging and drug development.

Sight and switch off: Nerve density visualization for interventions targeting nerves in prostate cancer

Nerve density is associated with prostate cancer (PCa) aggressiveness and prognosis. Thus far, no visualization methods have been developed to assess nerve density of PCa in vivo. We compounded propranolol-conjugated superparamagnetic iron oxide nerve peptide nanoparticles (PSN NPs), which achieved the nerve density visualization of PCa with high sensitivity and high specificity, and facilitated assessment of nerve density and aggressiveness of PCa using magnetic resonance imaging and magnetic particle imaging. Moreover, PSN NPs facilitated targeted therapy for PCa. PSN NPs increased the survival rate of mice with orthotopic PCa to 83.3% and decreased nerve densities and proliferation indexes by more than twofold compared with the control groups. The present study, thus, developed a technology to visualize the nerve density of PCa and facilitate targeted neural drug delivery to tumors to efficiently inhibit PCa progression. Our study provides a potential basis for clinical imaging and therapeutic interventions targeting nerves in PCa.

A dual-targeted theranostic photosensitizer based on a TADF fluorescein derivative

Specific diagnosis and therapy of cancer is still a challenge in biomedical research. Photodynamic therapy (PDT) has emerged as a novel therapeutic modality for cancer treatment. However, the traditional PDT photosensitizers often exhibit low specific selectivity. In this study, we have reported a dual-targeted theranostic photosensitizer FL-RGD by covalently conjugating tumor marker cyclic arginine-glycine-aspartic acid tripeptide (RGD) and a fluorescein derivative FL which has a property of thermally activated delayed fluorescence (TADF) and a long triplet lifetime for efficient PDT. The FL-RGD can target tumor tissues and further locate lysosomes of tumor cells to concurrently achieve the cancers' specific diagnosis and efficient treatment. The mechanism of its highly efficient PDT was attributed to the damage of lysosome via ¹O₂. Besides, FL-RGD has the potential to be utilized in depth imaging and treatment by two-photon excitation. The actual diagnosis performance of FL-RGD was proved by fluorescence imaging of living cells and tumor bearing mice. The therapy performance was proved by MTT assays, fluorescence-activated cell sorting (FACS) analysis and PDT experiments on tumor bearing mice. The research obviously exhibited the potential of FL-RGD for tumor theranostics in vivo and in vitro.

Photoacoustic imaging of integrin-overexpressing tumors using a novel ICG-based contrast agent in mice

PhotoAcoustic Imaging (PAI) is a biomedical imaging modality currently under evaluation in preclinical and clinical settings. In this work, ICG is coupled to an integrin binding vector (ICG-RGD) to combine the good photoacoustic properties of ICG and the favourable α_vβ₃-binding capabilities of a small RGD cyclic peptidomimetic. ICG-RGD is characterized in terms of physicochemical properties, biodistribution and imaging performance. Tumor uptake was assessed in subcutaneous xenograft mouse models of human glioblastoma (U-87MG, high α_vβ₃ expression) and epidermoid carcinoma (A431, low α_vβ₃ expression). ICG and ICG-RGD showed high PA signal in tumors already after 15 min post-injection. At later time points the signal of ICG rapidly decreased, while ICG-RGD showed sustained uptake in U-87MG but not in A431 tumors, likely due to the integrin-mediated retention of the probe. In conclusion, ICG-RGD is a novel targeted contrast agents for PAI with superior biodistribution, tumor uptake properties and diagnostic value compared to ICG.

A triple modality BSA-coated dendritic nanoplatform for NIR imaging, enhanced tumor penetration and anticancer therapy

Functional theranostic systems for drug delivery capable of concurrent near-infrared (NIR) fluorescence imaging, active tumor targeting and anticancer therapies are desired for concise cancer diagnosis and treatment. Dendrimers with controllable size and surface functionalities are good candidates for such platforms. However, integration of active targeting ligands and imaging agents separately on the surface or encapsulation of the imaging agents in the inner core of the dendrimers will result in a more complex composition or reduced drug loading efficiency. Herein, we reported a PAMAM-based theranostic system, with a simple integrin-specific imaging ligand prepared from two motifs. One motif is a NIR carbocyanine fluorescent dye (Cyp) for precise in vivo monitoring of the system and identification of tumor or cancer cells, and the other is a novel tumor-penetrating cyclic peptide (CRGDKGPDC, abbreviated iRGD). BSA was non-covalently bonded with Cyp to reduce NIR agent fluorescence-quenching aggregates and enhance imaging signals. The chemotherapy effect of these dendritic systems was achieved by encapsulating paclitaxel into the hydrophobic interior of the dendrimers. In vitro and in vivo targeting and penetrating studies revealed that a significantly high amount of the dendritic systems was endocytosed by HepG2 cells and enhanced accumulation and penetration at tumor sites. Our safety evaluation showed that masking of cationic-end groups of PAMAM to neutral or anionic groups has resulted in decreased or even zero-toxicity. The preliminary antitumor efficacy of the dendritic system was evaluated. In vitro and in vivo studies confirmed that paclitaxel-encapsulated functionalized PAMAM can efficiently kill HepG2 cancer cells. In conclusion, our functionalized theranostic dendritic system could be a promising nanocarrier to effectively deliver drugs to deep tumor regions for anticancer therapy.

Precise integrin-targeting near-infrared imaging-guided surgical method increases surgical qualification of peritoneal carcinomatosis from gastric cancer in mice

Peritoneal carcinomatosis from gastric cancer represents a common recurrent gastric cancer that seriously affects the survival, prognosis, and quality of life of patients at its advanced stage. In recent years, complete cytoreduction surgery in combination with hyperthermic intraperitoneal chemotherapy has been demonstrated to improve the survival and prognosis of patients with malignant tumors including peritoneal carcinomatosis from gastric cancer. Establishing viable methods of accurately assessing the tumor burden in patients with peritoneal carcinoma and correctly selecting suitable patients in order to improve cytoreduction surgical outcomes and reduce the risk of postoperative complications has become a challenge in the field of peritoneal carcinoma research. Here, we investigated peritoneal carcinomatosis from gastric cancer in a mouse model by using our self-developed surgical navigation system that combines optical molecular imaging with an integrin-targeting Arg-Gly-Asp-indocyanine green (RGD-ICG) molecular probe. The results showed that our diagnostic method could achieve a sensitivity and specificity of up to 93.93% and 100%, respectively, with a diagnostic index (DI) of 193.93% and diagnostic accuracy rate of 93.93%.Furthermore, the minimum tumor diameter measured during the surgery was 1.8 mm and the operative time was shortened by 3.26-fold when compared with the conventionally-treated control group. Therefore, our surgical navigation system that combines optical molecular imaging with an RGD-ICG molecular probe, could improve the diagnostic accuracy rate for peritoneal carcinomatosis from gastric cancer, shorten the operative time, and improve the quality of the cytoreduction surgery for peritoneal carcinomatosis from gastric cancer, thus providing a solid foundation for its future clinical development and application.

Multifunctional near-infrared light-triggered biodegradable micelles for chemo- and photo-thermal combination therapy

A combination of chemo- and photo-thermal therapy (PTT) has provided a promising efficient approach for cancer therapy. To achieve the superior synergistic chemotherapeutic effect with PTT, the development of a simple theranostic nanoplatform that can provide both cancer imaging and a spatial-temporal synchronism of both therapeutic approaches are highly desired. Our previous study has demonstrated that near-infrared (NIR) light-triggered biodegradable chitosan-based amphiphilic block copolymer micelles (SNSC) containing light-sensitive 2-nitrobenzyl alcohol and NIR dye cypate on the hydrophobic block could be used for fast light-triggered drug release. In this study, we conjugated the SNSC micelles with tumor targeting ligand c(RGDyK) and also encapsulated antitumor drug Paclitaxel (PTX). The results show that c(RGDyK)-modified micelles could enhance the targeting and residence time in tumor site, as well as be capable performing high temperature response for PTT on cancer cells and two-photon photolysis for fast release of anticancer drugs under NIR irradiation. In vitro release profiles show a significant controlled release effort that the release concentration of PTX from micelles was significantly increased with the exposure of NIR light. In vitro and in vivo antitumor studies demonstrate that, compared with chemo or PTT treatment alone, the combined treatment with the local exposure of NIR light exhibited significantly enhanced anti-tumor efficiency. These findings indicate that this system exhibited great potential in tumor-targeting imaging and synchronous chemo- and photo-thermal therapy.

Optical imaging of ovarian cancer using a matrix metalloproteinase-3-sensitive near-infrared fluorescent probe

Epithelial ovarian cancer (EOC) is the seventh most common cancer among women worldwide. The 5-year survival rate for women with EOC is only 30%-50%, which is largely due to the typically late diagnosis of this condition. EOC is difficult to detect in its early stage because of its asymptomatic nature. Recently, near-infrared fluorescent (NIRF) imaging has been developed as a potential tool for detecting EOC at the molecular level. In this study, a NIRF-sensitive probe was designed to detect matrix metalloproteinase (MMP) activity in ovarian cancer cells. A cyanine fluorochrome was conjugated to the amino terminus of a peptide substrate with enzymatic specificity for MMP-3. To analyze the novel MMP-3 probe, an in vivo EOC model was established by subcutaneously implanting SKOV3 cells, a serous-type EOC cell line, in mice. This novel MMP-3-sensitive probe specifically reacted with only the active MMP-3 enzyme, resulting in a significantly enhanced NIRF emission intensity. Histological analysis demonstrated that MMP-3 expression and activity were enhanced in the stromal cells surrounding the ovarian cancer cells. These studies establish a molecular imaging reporter for diagnosing early-stage EOC. Additional studies are required to confirm the early-stage activity of MMP-3 in EOC and its diagnostic and prognostic significance.

Real-time near-infrared fluorescence imaging using cRGD-ZW800-1 for intraoperative visualization of multiple cancer types

Incomplete resections and damage to critical structures increase morbidity and mortality of patients with cancer. Targeted intraoperative fluorescence imaging aids surgeons by providing real-time visualization of tumors and vital structures. This study evaluated the tumor-targeted zwitterionic near-infrared fluorescent peptide cRGD-ZW800-1 as tracer for intraoperative imaging of multiple cancer types. cRGD-ZW800-1 was validated in vitro on glioblastoma (U-87 MG) and colorectal (HT-29) cell lines. Subsequently, the tracer was tested in orthotopic mouse models with HT-29, breast (MCF-7), pancreatic (BxPC-3), and oral (OSC-19) tumors. Dose-ranging studies, including doses of 0.25, 1.0, 10, and 30 nmol, in xenograft tumor models suggest an optimal dose of 10 nmol, corresponding to a human equivalent dose of 63 μg/kg, and an optimal imaging window between 2 and 24 h post-injection. The mean half-life of cRGD-ZW800-1 in blood was 25 min. Biodistribution at 4 h showed the highest fluorescence signals in tumors and kidneys. In vitro and in vivo competition experiments showed significantly lower fluorescence signals when U-87 MG cells (minus 36%, p = 0.02) or HT-29 tumor bearing mice (TBR at 4 h 3.2 ± 0.5 vs 1.8 ± 0.4, p = 0.03) were simultaneously treated with unlabeled cRGD. cRGD-ZW800-1 visualized in vivo all colorectal, breast, pancreatic, and oral tumor xenografts in mice. Screening for off-target interactions, cRGD-ZW800-1 showed only inhibition of COX-2, likely due to binding of cRGD-ZW800-1 to integrin α_Vβ₃. Due to its recognition of various integrins, which are expressed on malignant and neoangiogenic cells, it is expected that cRGD-ZW800-1 will provide a sensitive and generic tool to visualize cancer during surgery.

Nanomedicine engulfed by macrophages for targeted tumor therapy

Macrophages, exhibiting high intrinsic accumulation and infiltration into tumor tissues, are a novel drug vehicle for directional drug delivery. However, the low drug-loading (DL) capacity and the drug cytotoxicity to the cell vehicle have limited the application of macrophages in tumor therapy. In this study, different drugs involving small molecular and nanoparticle drugs were loaded into intrinsic macrophages to find a better way to overcome these limitations. Their DL capacity and cytotoxicity to the macrophages were first compared. Furthermore, their phagocytic ratio, dynamic distributions, and tumoricidal effects were also investigated. Results indicated that more lipid-soluble molecules and DL particles can be phagocytized by macrophages than hydrophilic ones. In addition, the N-succinyl-N'-octyl chitosan (SOC) DL particles showed low cytotoxicity to the macrophage itself, while the dynamic biodistribution of macrophages engulfed with different particles/small molecules showed similar profiles, mainly excreted from liver to intestine pathway. Furthermore, macrophages loaded with SOC-paclitaxel (PTX) particles exhibited greater therapeutic efficacies than those of macrophages directly carrying small molecular drugs such as doxorubicin and PTX. Interestingly, macrophages displayed stronger targeting ability to the tumor site hypersecreting chemokine in immunocompetent mice in comparison to the tumor site secreting low levels of chemokine in immunodeficiency mice. Finally, results demonstrated that macrophages carrying SOC-PTX are a promising pharmaceutical preparation for tumor-targeted therapy.

Compact solid-state CMOS single-photon detector array for in vivo NIR fluorescence lifetime oncology measurements

In near infrared fluorescence-guided surgical oncology, it is challenging to distinguish healthy from cancerous tissue. One promising research avenue consists in the analysis of the exogenous fluorophores' lifetime, which are however in the (sub-)nanosecond range. We have integrated a single-photon pixel array, based on standard CMOS SPADs (single-photon avalanche diodes), in a compact, time-gated measurement system, named FluoCam. In vivo measurements were carried out with indocyanine green (ICG)-modified derivatives targeting the αvβ 3 integrin, initially on a genetically engineered mouse model of melanoma injected with ICG conjugated with tetrameric cyclic pentapeptide (ICG-E[c(RGD f K)4]), then on mice carrying tumour xenografts of U87-MG (a human primary glioblastoma cell line) injected with monomeric ICG-c(RGD f K). Measurements on tumor, muscle and tail locations allowed us to demonstrate the feasibility of in vivo lifetime measurements with the FluoCam, to determine the characteristic lifetimes (around 500 ps) and subtle lifetime differences between bound and unbound ICG-modified fluorophores (10% level), as well as to estimate the available photon fluxes under realistic conditions.

A Hybrid Peptide PTS that Facilitates Transmembrane Delivery and Its Application for the Rapid In vivo Imaging via Near-Infrared Fluorescence Imaging

Background and purpose: Intravital imaging provides invaluable readouts for clinical diagnoses and therapies and shows great potential in the design of individualized drug dosage regimes. Ts is a mammalian free cell membrane-penetrating peptide. This study aimed to introduce a novel approach to the design of a cancer-selective peptide on the basis of a membrane-penetrating peptide and to explore its potential as a carrier of medical substances.

Experimental approach:Ts was linked with a αvβ3-binding peptide P1c to create a hybrid referred to as PTS. The hybrid was labeled with an FITC or Cy5.5 as an imaging indicator to evaluate its in vitro and in vivo bioactivity.

Key results:Hemolysis tests proved that in comparison with Ts, PTS caused similar or even less leakage of human erythrocytes at concentrations of up to 1 mmol/L. Flow cytometry assay and confocal microscopy demonstrated the following. (1) P1c alone could target and mostly halt at the cancer cell membrane. (2) Ts alone could not bind to the membrane sufficiently. (3) P1c greatly enhanced the binding affinity of PTS with MDA-MB-231 breast cancer cells that upregulated αvβ3. (4) Ts conferred PTS with the ability to traverse a cell membrane and thus facilitate the transmembrane delivery of imaging probes. In vivo near-infrared fluorescence (NIRF) imaging demonstrated that the imaging probes were rapidly concentrated in a MDA-MB-231 tumor tissue within 1 h after intravenous injection.

Conclusions and implications:PTS exhibited the capability of targeting specific tumors and greatly facilitating the transmembrane delivery of imaging probes.

In Vivo Fluorescence Reflectance Imaging with Subcutaneous Mouse Tumor Models

Optical imaging is undoubtedly one of the most versatile and widely used imaging techniques in both research and clinical practice. Among optical imaging technologies, fluorescence imaging is the most popularly used and has become an essential tool in biomedical science. A key component of fluorescence imaging is fluorescence-producing reporters, including fluorescent dyes and conjugates, as well as fluorescent proteins. For in vivo imaging applications, fluorophores with long emission at the near-infrared (NIR) region are generally preferred to overcome the photon attenuation in living tissue. Here, we describe the in vivo fluorescence imaging of an integrin αυβ3 targeted NIR fluorescent probe (cRGD-ICG-Der-02) using subcutaneous mouse tumor models.

Impact of Substituents in Tumor Uptake and Fluorescence Imaging Ability of Near-Infrared Cyanine-like Dyes

This report presents a simple strategy to introduce various functionalities in a cyanine dye (bis-indole-N-butylsulfonate-polymethine bearing a fused cyclic chloro-cyclohexene ring structure), and assess the impact of these substitutions in tumor uptake, retention and imaging. The results obtained from the structural activity relationship (SAR) study demonstrate that certain structural features introduced in the cyanine dye moiety make a remarkable difference in tumor avidity. Among the compounds investigated, the symmetrical CDs containing an amino-phenyl thioether group attached to a cyclohexene ring system and the two N-butyl linkers with terminal sulfonate groups in benzoindole moieties exhibited excellent tumor imaging ability in BALB/c mice bearing Colon26 tumors. Compared to indocyanine green (ICG), approved by FDA as a blood pooling agent, which has also been investigated for the use in tumor imaging, the modified CD selected on the basis of SAR study produced enhanced uptake and longer retention in tumor(s). A facile approach reported herein for introducing a variety of functionalities in tumor-avid CD provides an opportunity to create multi-imaging modality agent(s). Using a combination of mass spectrometry and absorbance techniques, the photobleaching of one of the CDs was analyzed and significant regioselective photooxidation was observed.

The targeting mechanism of DHA ligand and its conjugate with Gemcitabine for the enhanced tumor therapy

Docosahexaenoic acid (DHA), an omega-3 C22 natural fatty acid serving as a precursor for metabolic and biochemical pathways, was reported as a targeting ligand of anticancer drugs. However, its tumor targeting ability and mechanism has not been claimed. Here we hypothesized that the uptake of DHA by tumor cells is related to the phosphatidylethanolamine (PE) contents in cell membranes. Thus, in this manuscript, the tumor-targeting ability of DHA was initially demonstrated in vitro and in vivo on different tumor cell lines by labeling DHA with fluorescence dyes. Subsequently, the tumor targeting ability was then correlated with the contents of PE in cell membranes to study the uptake mechanism. Further, DHA was conjugated with anticancer drug gemcitabine (DHA-GEM) for targeted tumor therapy. Our results demonstrated that DHA exhibited high tumor targeting ability and PE is the main mediator, which confirmed our hypothesis. The DHA-GEM displayed enhanced therapeutic efficacy than that of GEM itself, indicating that DHA is a promising ligand for tumor targeted therapy.

Small sized EGFR1 and HER2 specific bifunctional antibody for targeted cancer therapy

Targeting tumors using miniature antibodies is a novel and attractive therapeutic approach, as these biomolecules exhibit low immunogenicity, rapid clearance, and high targeting specificity. However, most of the small-sized antibodies in existence do not exhibit marked anti-tumor effects, which limit their use in targeted cancer immunotherapy. To overcome this difficulty in targeting multiple biomarkers by combination therapies, we designed a new bifunctional antibody, named MaAbNA (multivalent antibody comprised of nanobody and affibody moieties), capable of targeting EGFR1 and HER2, which are widely overexpressed in a variety of tumor types. The small-sized (29 kDa) MaAbNA, which was expressed in E.coli, consists of one anti-EGFR1 nanobody and two anti-HER2 affibodies, and possesses high affinity (KD) for EGFR1 (~4.1 nM) and HER2 (~4.7 nM). In order to enhance its anti-tumor activity, MaAbNA was conjugated with adriamycin (ADM) using a PEG2000 linker, forming a new complex anticancer drug, MaAbNA-PEG2000-ADM. MaAbNA exhibited high inhibitory effects on tumor cells over-expressing both EGFR1 and HER2, but displayed minimal cytotoxicity in cells expressing low levels of EGFR1 and HER2. Moreover, MaAbNA-PEG2000-ADM displayed increased tumoricidal effects than ADM or MaAbNA alone, as well exhibited greater antitumor efficacy than EGFR1 (Cetuximab) and HER2 (Herceptin) antibody drugs. The ability of MaAbNA to regulate expression of downstream oncogenes c-jun, c-fos, c-myc, as well as AEG-1 for therapeutic potential was evaluated by qPCR and western-blot analyses. The antitumor efficacy of MaAbNA and its derivative MaAbNA-PEG2000-ADM were validated in vivo, highlighting the potential for use of MaAbNA as a highly tumor-specific dual molecular imaging probe and targeted cancer therapeutic.

In vivo near-infrared fluorescence imaging of FAP-expressing tumors with activatable FAP-targeted, single-chain Fv-immunoliposomes

Molecular and cellular changes that precede the invasive growth of solid tumors include the release of proteolytic enzymes and peptides in the tumor stroma, the recruitment of phagocytic and lymphoid infiltrates and alteration of the extracellular matrix. The reactive tumor stroma consists of a large number of myofibroblasts, characterized by high expression of fibroblast activation protein alpha (FAP). FAP, a type-II transmembrane sialoglycoprotein is an attractive target in diagnosis and therapy of several pathologic disorders especially cancer. In the underlying work, a fluorescence-activatable liposome (fluorescence-quenched during circulation and fluorescence activation upon cellular uptake), bearing specific single-chain Fv fragments directed against FAP (scFv'FAP) was developed, and its potential for use in fluorescence diagnostic imaging of FAP-expressing tumor cells was evaluated by whole body fluorescence imaging. The liposomes termed anti-FAP-IL were prepared via post-insertion of ligand-phospholipid-conjugates into preformed DY-676-COOH-containing liposomes. The anti-FAP-IL revealed a homogeneous size distribution and showed specific interaction and binding with FAP-expressing cells in vitro. The high level of fluorescence quenching of the near-infrared fluorescent dye sequestered in the aqueous interior of the liposomes enables fluorescence imaging exclusively upon uptake and degradation by cells, which results in fluorescence activation. Only FAP-expressing cells were able to take up and activate fluorescence of anti-FAP-IL in vitro. Furthermore, anti-FAP-IL accumulated selectively in FAP-expressing xenograft models in vivo, as demonstrated by blocking experiments using free scFv'FAP. The local tumor fluorescence intensities were in agreement with the intrinsic degree of FAP-expression in different xenograft models. Thus, anti-FAP-IL can serve as a suitable in vivo diagnostic tool for pathological disorders accompanied by high FAP-expression.

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.

The antitumor activity of a doxorubicin loaded, iRGD-modified sterically-stabilized liposome on B16-F10 melanoma cells: in vitro and in vivo evaluation

Considering the fact that iRGD (tumor-homing peptide) demonstrates tumor-targeting and tumor-penetrating activity, and that B16-F10 (murine melanoma) cells overexpress both αv integrin receptor and neuropilin-1 (NRP-1), the purpose of this study was to prepare a novel doxorubicin (DOX)-loaded, iRGD-modified, sterically-stabilized liposome (SSL) (iRGD-SSL-DOX) in order to evaluate its antitumor activity on B16-F10 melanoma cells in vitro and in vivo. The iRGD-SSL-DOX was prepared using a thin-film hydration method. The characteristics of iRGD-SSL-DOX were evaluated. The in vitro leakage of DOX from iRGD-SSL-DOX was tested. The in vitro tumor-targeting and tumor-penetrating characteristics of iRGD-modified liposomes on B16-F10 cells were investigated. The in vivo tumor-targeting and tumor-penetrating activities of iRGD-modified liposomes were performed in B16-F10 tumor-bearing nude mice. The antitumor effect of iRGD-SSL-DOX was evaluated in B16-F10 tumor-bearing C57BL/6 mice in vivo. The average particle size of the iRGD-SSL-DOX was found to be 91 nm with a polydispersity index (PDI) of 0.16. The entrapment efficiency of iRGD-SSL-DOX was 98.36%. The leakage of DOX from iRGD-SSL-DOX at the 24-hour time point was only 7.5%. The results obtained from the in vitro flow cytometry and confocal microscopy, as well as in vivo biodistribution and confocal immunofluorescence microscopy experiments, indicate that the tumor-targeting and tumor-penetrating activity of the iRGD-modified SSL was higher than that of unmodified SSL. In vivo antitumor activity results showed that the antitumor effect of iRGD-SSL-DOX against melanoma tumors was higher than that of SSL-DOX in B16-F10 tumor-bearing mice. In conclusion, the iRGD-SSL-DOX is a tumor-targeting and tumor-penetrating peptide modified liposome which has significant antitumor activity against melanoma tumors.

Near-infrared light-triggered micelles for fast controlled drug release in deep tissue

In this manuscript, a near-infrared (NIR) light-breakable amphiphilic block copolymer N-succinyl-N'-4-(2-nitrobenzyloxy)-succinyl-chitosan micelles (SNSC), containing light-sensitive triggering group 2-nitrobenzyl alcohol on the hydrophobic block, was developed. The UV-Vis absorption spectra, Fourier Transform Infrared (FTIR) spectra, and (1)H nuclear magnetic resonance ((1)H NMR) spectra were characterized to confirm the successful synthesis of the micelles. Two-photon photolysis of SNSC micelles was displayed by transmission electron microscopy (TEM). By encapsulating a NIR dye cypate (Ex/Em: 780/808 nm) into the hydrophobic core of the micelles, the dissociation of the micelles under NIR illumination was greatly accelerated, enabling a controlled fast release of co-loaded hydrophobic species in the micelles. In vivo distribution and acute toxicity of the NIR light-sensitive micelles were also investigated to verify the low cytotoxicity of the micelles. Results indicate that this system provides an efficient method to surmount the drawback of UV or visible light-responsive polymeric systems for controlled drug release in deep tissues.