Near-infrared quantum dots for HER2 localization and imaging of cancer cells

Surface Functionalization of Gold Nanoparticles for Targeting the Tumor Microenvironment to Improve Antitumor Efficiency

Gold nanoparticles (AuNPs) have undergone significant research for their use in the treatment of cancer. Numerous researchers have established their potent antitumor properties, which have greatly impacted the treatment of cancer. AuNPs have been used in four primary anticancer treatment modalities, namely radiation, photothermal therapy, photodynamic therapy, and chemotherapy. However, the ability of AuNPs to destroy cancer is lacking and can even harm healthy cells without the right direction to transport them to the tumor microenvironment. Consequently, a suitable targeting technique is needed. Based on the distinct features of the human tumor microenvironment, this review discusses four different targeting strategies that target the four key features of the tumor microenvironment, including abnormal vasculature, overexpression of specific receptors, an acidic microenvironment, and a hypoxic microenvironment, to direct surface-functionalized AuNPs to the tumor microenvironment and increase antitumor efficacies. In addition, some current completed or ongoing clinical trials of AuNPs will also be discussed below to further reinforce the concept of using AuNPs in anticancer therapy.

A Critical Scrutiny on Liposomal Nanoparticles Drug Carriers as Modelled by Topotecan Encapsulation and Release in Treating Cancer

The medical field is looking for drugs and/or ways of delivering drugs without harming patients. A number of severe drug side effects are reported, such as acute kidney injury (AKI), hepatotoxicity, skin rash, and so on. Nanomedicine has come to the rescue. Liposomal nanoparticles have shown great potential in loading drugs, and delivering drugs to specific targeted sites, hence achieving a needed bioavailability and steady state concentration, which is achieved by a controlled drug release ability by the nanoparticles. The liposomal nanoparticles can be conjugated to cancer receptor tags that give the anticancer-loaded nanoparticles specificity to deliver anticancer agents only at cancerous sites, hence circumventing destruction of normal cells. Also, the particles are biocompatible. The drugs are shielded by attack from the liver and other cytochrome P450 enzymes before reaching the desired sites. The challenge, however, is that the drug release is slow by these nanoparticles on their own. Scientists then came up with several ways to enhance drug release. Magnetic fields, UV light, infrared light, and so on are amongst the enhancers used by scientists to potentiate drug release from nanoparticles. In this paper, synthesis of liposomal nanoparticle formulations (liposomal-quantum dots (L-QDs), liposomal-quantum dots loaded with topotecan (L-QD-TPT)) and their analysis (cytotoxicity, drug internalization, loading efficiency, drug release rate, and the uptake of the drug and nanoparticles by the HeLa cells) are discussed.

HER-2-Targeted Nanoparticles for Breast Cancer Diagnosis and Treatment

Simple Summary

Despite tremendous efforts in finding new therapeutic strategies and promoting screening programs to increase early diagnosis, breast cancer is still a major cause of death in the female worldwide population. Preclinical and clinical evidence have shown that nanotechnologies can significantly contribute to improving both therapeutic and diagnostic aspects. This is particularly true for human epidermal growth factor receptor-2 (HER-2) overexpressing (HER-2⁺) breast cancer, where recurrence rates and drug resistance still make it one of the most aggressive breast cancer subtypes, despite the development of promising targeted therapies. The aim of this review is to provide an update on the most promising nanoparticle-based approaches developed in the last decade in the context of HER-2-positive breast cancer therapy and diagnosis.

Abstract

Human epidermal growth factor receptor-2 (HER-2) overexpressing breast cancer is a breast cancer subtype characterized by high aggressiveness, high frequency of brain metastases and poor prognosis. HER-2, a glycoprotein belonging to the ErbB receptor family, is overexpressed on the outer membrane of cancer cells and has been an important therapeutic target for the development of targeted drugs, such as the monoclonal antibodies trastuzumab and pertuzumab. These therapies have been available in clinics for more than twenty years. However, despite the initial enthusiasm, a major issue emerged limiting HER-2 targeted therapy efficacy, i.e., the evolution of drug resistance, which could be tackled by nanotechnology. The aim of this review is to provide a first critical update on the different types of HER-2-targeted nanoparticles that have been proposed in the literature in the last decade for therapeutic purposes. We focus on the different targeting strategies that have been explored, their relative outcomes and current limitations that still need to be improved. Then, we review the nanotools developed as diagnostic kits, focusing on the most recent techniques, which allow accurate quantification of HER-2 levels in tissues, with the aim of promoting more personalized medicinal approaches in patients.

Quantum Dots: Synthesis, Antibody Conjugation, and HER2-Receptor Targeting for Breast Cancer Therapy

Breast cancer is becoming one of the main lethal carcinomas in the recent era, and its occurrence rate is increasing day by day. There are different breast cancer biomarkers, and their overexpression takes place in the metastasis of cancer cells. The most prevalent breast cancer biomarker is the human epidermal growth factor receptor2 (HER2). As this biomarker is overexpressed in malignant breast tissues, it has become the main focus in targeted therapies to fight breast cancer. There is a cascade of mechanisms involved in metastasis and cell proliferation in cancer cells. Nanotechnology has become extremely advanced in targeting and imaging cancerous cells. Quantum dots (QDs) are semiconductor NPs, and they are used for bioimaging, biolabeling, and biosensing. They are synthesized by different approaches such as top-down, bottom-up, and synthetic methods. Fully human monoclonal antibodies synthesized using transgenic mice having human immunoglobulin are used to target malignant cells. For the HER2 receptor, herceptin® (trastuzumab) is the most specific antibody (Ab), and it is conjugated with QDs by using different types of coupling mechanisms. This quantum dot monoclonal antibody (QD-mAb) conjugate is localized by injecting it into the blood vessel. After the injection, it goes through a series of steps to reach the intracellular space, and bioimaging of specifically the HER2 receptor occurs, where apoptosis of the cancer cells takes place either by the liberation of Ab or the free radicals.

Nanotechnology approaches to addressing HER2-positive breast cancer

Breast cancer is a major cause of cancer-associated deaths in the United States. It was estimated that 12% of women in the U.S. will develop invasive breast cancer in their lifetime. The human epidermal growth factor receptor (HER2/neu) is a growth-promoting protein that is overexpressed in 15–20% of breast cancers (HER2-positive breast cancer). HER2-positive breast cancer generally grows and spreads more quickly than other breast cancers, but it can be targeted therapeutically. Targeting drugs have been developed with a specific design to stop the growth and even the spread of cancer. These drugs include trastuzumab (Herceptin), pertuzumab (Perjeta), ado-trastuzumab emtansine (Kadcyla, or TDM-1), fam-trastuzumab deruxtecan, lapatinib, neratinib and tucatinib. However, the need for better targeted therapy and efficacy still exists. Nanotechnology could have major advantages in terms of detection, targeting, drug delivery, and destruction of cancer cells and tumors. Although a great deal of progress has been accomplished major challenges still need to be addressed. In this review, we examine the major areas of research in the area of nanotechnology and HER2-positive breast cancer.

Superior Properties and Biomedical Applications of Microorganism-Derived Fluorescent Quantum Dots

Quantum dots (QDs) are fluorescent nanocrystals with superb photo-physical properties. Applications of QDs have been exponentially increased during the past decade. They can be employed in several disciplines, including biological, optical, biomedical, engineering, and energy applications. This review highlights the structural composition and distinctive features of QDs, such as resistance to photo-bleaching, wide range of excitations, and size-dependent light emission features. Physical and chemical preparation of QDs have prominent downsides, including high costs, regeneration of hazardous byproducts, and use of external noxious chemicals for capping and stabilization purposes. To eliminate the demerits of these methods, an emphasis on the latest progress of microbial synthesis of QDs by bacteria, yeast, and fungi is introduced. Some of the biomedical applications of QDs are overviewed as well, such as tumor and microRNA detection, drug delivery, photodynamic therapy, and microbial labeling. Challenges facing the microbial fabrication of QDs are discussed with the future prospects to fully maximize the yield of QDs by elucidating the key enzymes intermediating the nucleation and growth of QDs. Exploration of the distribution and mode of action of QDs is required to promote their biomedical applications.

Emerging Nanopharmaceuticals and Nanonutraceuticals in Cancer Management

Nanotechnology is the science of nanoscale, which is the scale of nanometers or one billionth of a meter. Nanotechnology encompasses a broad range of technologies, materials, and manufacturing processes that are used to design and/or enhance many products, including medicinal products. This technology has achieved considerable progress in the oncology field in recent years. Most chemotherapeutic agents are not specific to the cancer cells they are intended to treat, and they can harm healthy cells, leading to numerous adverse effects. Due to this non-specific targeting, it is not feasible to administer high doses that may harm healthy cells. Moreover, low doses can cause cancer cells to acquire resistance, thus making them hard to kill. A solution that could potentially enhance drug targeting and delivery lies in understanding the complexity of nanotechnology. Engineering pharmaceutical and natural products into nano-products can enhance the diagnosis and treatment of cancer. Novel nano-formulations such as liposomes, polymeric micelles, dendrimers, quantum dots, nano-suspensions, and gold nanoparticles have been shown to enhance the delivery of drugs. Improved delivery of chemotherapeutic agents targets cancer cells rather than healthy cells, thereby preventing undesirable side effects and decreasing chemotherapeutic drug resistance. Nanotechnology has also revolutionized cancer diagnosis by using nanotechnology-based imaging contrast agents that can specifically target and therefore enhance tumor detection. In addition to the delivery of drugs, nanotechnology can be used to deliver nutraceuticals like phytochemicals that have multiple properties, such as antioxidant activity, that protect cells from oxidative damage and reduce the risk of cancer. There have been multiple advancements and implications for the use of nanotechnology to enhance the delivery of both pharmaceutical and nutraceutical products in cancer prevention, diagnosis, and treatment.

Ultrasonic-assisted synthesis and in vitro biological assessments of a novel herceptin-stabilized graphene using three dimensional cell spheroid

In vivo assays of graphene and its derivatives are big challenges in biological evaluations because they require simultaneous long-term stability in aqueous dispersion and controllable systemic toxicity. Bifunctional graphene nanosheets which have key function in biomedical area are expected to address this challenge. Here, novel bifunctional graphene nanosheets were successfully synthesized in the presence of Herceptin, a natural antibody, using a facile ultrasonic-assisted method. Graphite layers were successfully exfoliated which resulted excellent stability of separated layers in herceptin solution. In aqueous solution, graphene concentration was effectively controlled by varying the herceptin content and sonication time. Furthermore, the toxicity of graphene was tested in both 2D and 3D spheroid cultures. The results showed that graphene toxicity were considerably reduced in spheroid culture compared to the 2D culture data. Moreover, the toxicity behavior of graphene was dependent on the exposed concentration of graphene that the mortality rate was significantly decreased when the concentration of graphene was below 1 µg/mL. This bifunctional graphene which possessed long-term stability in aqueous solutions and induced slight toxicity offers a promising nanostructure in tumor-targeted drug delivery, regenerative medicine and tissue engineering. This proof-of-concept study demonstrates the feasibility of ultrasonic assisted method in one-step synthesis of bifunctional nanomaterials and biostructures for clinical applications.

Preclinical Molecular Imaging for Precision Medicine in Breast Cancer Mouse Models

Precision and personalized medicine is gaining importance in modern clinical medicine, as it aims to improve diagnostic precision and to reduce consequent therapeutic failures. In this regard, prior to use in human trials, animal models can help evaluate novel imaging approaches and therapeutic strategies and can help discover new biomarkers. Breast cancer is the most common malignancy in women worldwide, accounting for 25% of cases of all cancers and is responsible for approximately 500,000 deaths per year. Thus, it is important to identify accurate biomarkers for precise stratification of affected patients and for early detection of responsiveness to the selected therapeutic protocol. This review aims to summarize the latest advancements in preclinical molecular imaging in breast cancer mouse models. Positron emission tomography (PET) imaging remains one of the most common preclinical techniques used to evaluate biomarker expression in vivo, whereas magnetic resonance imaging (MRI), particularly diffusion-weighted (DW) sequences, has been demonstrated as capable of distinguishing responders from nonresponders for both conventional and innovative chemo- and immune-therapies with high sensitivity and in a noninvasive manner. The ability to customize therapies is desirable, as this will enable early detection of diseases and tailoring of treatments to individual patient profiles. Animal models remain irreplaceable in the effort to understand the molecular mechanisms and patterns of oncologic diseases.

Quantum Dot-Based Simultaneous Multicolor Imaging

Quantum dots have attracted a great deal of attention among researchers in optical imaging because of their unique physicochemical properties. Their adjustable size allows quantum dots to emit visible fluorescence with different wavelengths excited by a single light source, allowing them to play an unmatched role in multitarget simultaneous multicolor imaging of tissues and cells compared with other molecular biotechnologies and traditional fluorescent materials. This technology affords real-time observation in situ of multiple biomarkers, allowing us to quantify their expression levels, and helping us to gain a deeper understanding of the interactions among biomolecules and the relationship between biomolecules and disease occurrence, progression, and prognosis. This has potential to aid in clinical diagnosis and treatment decision making.

Mathematical modeling of drug-induced receptor internalization in the HER2-positive SKBR3 breast cancer cell-line

About 20% of breast cancer tumors over-express the HER2 receptor. Trastuzumab, an approved drug to treat this type of breast cancer, is a monoclonal antibody directly binding at the HER2 receptor and ultimately inhibiting cancer cell growth. The goal of our study was to understand the early impact of trastuzumab on HER2 internalization and recycling in the HER2-overexpressing breast cancer cell line SKBR3. To this end, fluorescence microscopy, monitoring the amount of HER2 expression in the plasma membrane, was combined with mathematical modeling to derive the flux of HER2 receptors from and to the membrane. We constructed a dynamic multi-compartment model based on ordinary differential equations. To account for cancer cell heterogeneity, a first, dynamic model was expanded to a second model including two distinct cell phenotypes, with implications for different conformational states of HER2, i.e. monomeric or homodimeric. Our mathematical model shows that the hypothesis of fast constitutive HER2 recycling back to the plasma membrane does not match the experimental data. It conclusively describes the experimental observation that trastuzumab induces sustained receptor internalization in cells with membrane ruffles. It is also concluded that for rare, non-ruffled (flat) cells, HER2 internalization occurs three orders of magnitude slower than for the bulk, ruffled cell population.

Medical imaging modalities using nanoprobes for cancer diagnosis: A literature review on recent findings

Medical imaging modalities are used for different types of cancer detection and diagnosis. Recently, there have been a lot of studies on developing novel nanoparticles as new medical imaging contrast agents for the early detection of cancer. The aim of this review article is to categorize the medical imaging modalities accompanying with using nanoparticles to improve potential imaging for cancer detection and hence valuable therapy in the future. Nowadays, nanoparticles are becoming potentially transformative tools for cancer detection for a wide range of imaging modalities, including computed tomography (CT), magnetic resonance imaging, single photon emission CT, positron emission tomography, ultrasound, and optical imaging. The study results seen in the recent literature provided and discussed the diagnostic performance of imaging modalities for cancer detections and their future directions. With knowledge of the correlation between the application of nanoparticles and medical imaging modalities and with the development of targeted contrast agents or nanoprobes, they may provide better cancer diagnosis in the future.

Single molecule localization microscopy coupled with touch preparation for the quantification of trastuzumab-bound HER2

All breast cancers are assessed for levels of human epidermal growth factor receptor 2 (HER2). Fluorescence in situ hybridization (FISH) and immunohistochemistry are currently used to determine if a patient is eligible for anti-HER2 therapy. Limitations of both tests include variability and relatively long processing times. Additionally, neither test determines whether HER2 contains the extracellular domain. While truncated in some tumors, this domain is required for binding of the therapeutic antibody trastuzumab. Here, trastuzumab was used to directly detect HER2 with quantitative single molecule localization microscopy (qSMLM). In proof of concept studies, our new method rapidly quantified both HER2 density and features of nano-organization. In cultured cells, the method was sensitive to subtle variations in HER2 expression. To assess patient samples, we combined qSMLM with tissue touch preparation (touch prep-qSMLM) and examined large areas of intact membranes. For cell lines and patient samples, HER2 copy numbers from FISH showed a significant positive correlation with detected densities from qSMLM and trended with HER2 cluster occupancy.

The prognostic value of quantitative analysis of CCL5 and collagen IV in luminal B (HER2-) subtype breast cancer by quantum-dot-based molecular imaging

Objective

Breast cancer is the most common malignancy and one of the main causes of death in women. Luminal B (HER2−) breast cancer subtype has been proposed since the 2011 St Gallon consensus. The hormone receptor status in this type of breast cancer is positive; thus, endocrine therapy was performed in all cases, but the treatment was not satisfactory, and a significant number of cases received very little benefit from chemotherapy. Furthermore, there is no effective treatment target for this subtype. Luminal B (HER2−) breast cancer subtype has been proposed since the 2011 St Gallon consensus. Therefore, the study of the key molecules in the microenvironment of breast cancer can help to reveal the biological characteristics.

Patients and methods

Luminal B (HER2−) breast cancer is a subtype with higher heterogeneity and poorer prognosis than luminal A. It is known that the development of cancer cells is an active process, and this process needs microenvironment cytokines, including chemokine (C–C motif) ligand 5 (CCL5) and collagen IV. Therefore, CCL5 and collagen IV were imaged and detected by quantum dot, and the CCL5/collagen IV ratio was calculated to investigate the prognostic value of the CCL5/collagen IV ratio in luminal B (HER2−).

Results

Quantitative determination showed a statistically significant negative correlation between CCL5 and collagen IV. The 5-year disease-free survival (5-DFS) of the high and low CCL5/collagen IV ratio subgroups was significantly different. The CCL5/collagen IV ratio had a greater prognostic value for 5-DFS. The CCL5/collagen IV ratio was an independent prognostic indicator.

Conclusion

Our findings revealed the effective integration of tumor CCL5 and collagen IV, and a new method for predicting the prognosis of luminal B (HER2−) has been developed.

3D Imaging Detection of HER2 Based in the Use of Novel Affibody-Quantum Dots Probes and Ratiometric Analysis

Patients with breast cancer (BC) overexpressing HER2 (HER2+) are selected for Trastuzumab treatment, which blocks HER2 and improves cancer prognosis. However, HER2+ diagnosis, by the gold standard, immunohistochemistry, could lead to errors, associated to: a) variability in sample manipulation (thin 2D sections), b) use of subjective algorithms, and c) heterogeneity of HER2 expression within the tissue. Therefore, we explored HER2 3D detection by multiplexed imaging of Affibody-Quantum Dots conjugates (Aff-QD), ratiometric analysis (RMAFI) and thresholding, using BC multicellular tumor spheroids (BC-MTS) (~120 μm of diameter) as 3D model of BC. HER2+, HER2- and hybrid HER2+/- BC-MTS (mimicking heterogeneous tissue) were incubated simultaneously with two Aff-QD probes (anti-HER2 and negative control (NC), respectively, (1:1)). Confocal XY sections were recorded along the Z distance, and processed by automatized RMAFI (anti-HER2 Aff-QD/ NC). Quantifying the NC fluorescence allowed to predict the fraction of non-specific accumulation of the anti-HER2 probe within the thick sample, and resolve the specific HER2 level. HER2 was detected up to 30μm within intact BC-MTS, however, permeabilization improved detection up to 70μm. Specific HER2 signal was objectively quantified, and HER2 3D-density of 9.2, 48.3 and 30.8% were obtained in HER2-, HER2+ and hybrid HER2+/- permeabilized BC-MTS, respectively. Therefore, by combining the multiplexing capacity of Aff-QD probes and RMAFI, we overcame the challenge of non-specific probe accumulation in 3D samples with minimal processing, yielding a fast, specific spatial HER2 detection and objective quantification.

Single- and two-photon imaging of human micrometastases and disseminated tumour cells with conjugates of nanobodies and quantum dots

Early detection of malignant tumours and, especially, micrometastases and disseminated tumour cells is still a challenge. In order to implement highly sensitive diagnostic tools we demonstrate the use of nanoprobes engineered from nanobodies (single-domain antibodies, sdAbs) and fluorescent quantum dots (QDs) for single- and two-photon detection and imaging of human micrometastases and disseminated tumour cells in ex vivo biological samples of breast and pancreatic metastatic tumour mouse models expressing human epidermal growth factor receptor 2 (HER2) or carcinoembryonic antigen (CEA). By staining thin (5–10 µm) paraffin and thick (50 µm) agarose tissue sections, we detected HER2- and CEA-positive human tumour cells infiltrating the surrounding tissues or metastasizing to different organs, including the brain, testis, lung, liver, and lymph nodes. Compared to conventional fluorescently labelled antibodies the sdAb-HER2-QD and sdAb-CEA-QD nanoprobes are superior in detecting micrometastases in tissue sections by lower photobleaching and higher brightness of fluorescence signals ensuring much better discrimination of positive signals versus background. Very high two-photon absorption cross-sections of QDs and small size of the nanoprobes ensure efficient imaging of thick tissue sections unattainable with conventional fluorescent probes. The nanobody–QD probes will help to improve early cancer diagnosis and prognosis of progression by assessing metastasis.

Dependence of Nanoparticle Toxicity on Their Physical and Chemical Properties

Studies on the methods of nanoparticle (NP) synthesis, analysis of their characteristics, and exploration of new fields of their applications are at the forefront of modern nanotechnology. The possibility of engineering water-soluble NPs has paved the way to their use in various basic and applied biomedical researches. At present, NPs are used in diagnosis for imaging of numerous molecular markers of genetic and autoimmune diseases, malignant tumors, and many other disorders. NPs are also used for targeted delivery of drugs to tissues and organs, with controllable parameters of drug release and accumulation. In addition, there are examples of the use of NPs as active components, e.g., photosensitizers in photodynamic therapy and in hyperthermic tumor destruction through NP incorporation and heating. However, a high toxicity of NPs for living organisms is a strong limiting factor that hinders their use in vivo. Current studies on toxic effects of NPs aimed at identifying the targets and mechanisms of their harmful effects are carried out in cell culture models; studies on the patterns of NP transport, accumulation, degradation, and elimination, in animal models. This review systematizes and summarizes available data on how the mechanisms of NP toxicity for living systems are related to their physical and chemical properties.

Theranostic Liposome-Nanoparticle Hybrids for Drug Delivery and Bioimaging

Advanced theranostic nanomedicine is a multifunctional approach which combines the diagnosis and effective therapy of diseased tissues. Here, we investigated the preparation, characterization and in vitro evaluation of theranostic liposomes. As is known, liposome–quantum dot (L–QD) hybrid vesicles are promising nanoconstructs for cell imaging and liposomal-topotecan (L-TPT) enhances the efficiency of TPT by providing protection against systemic clearance and allowing extended time for it to accumulate in tumors. In the present study, hydrophobic CdSe/ZnS QD and TPT were located in the bilayer membrane and inner core of liposomes, respectively. Dynamic light scattering (DLS), zeta potential (ζ) measurements and fluorescence/absorption spectroscopy were performed to determine the vesicle size, charge and spectroscopic properties of the liposomes. Moreover, drug release was studied under neutral and acidic pH conditions. Fluorescence microscopy and flow cytometry analysis were used to examine the cellular uptake and intracellular distribution of the TPT-loaded L–QD formulation. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to investigate the in vitro cytotoxicity of the formulations on HeLa cells. According to the results, the TPT-loaded L–QD hybrid has adequate physicochemical properties and is a promising multifunctional delivery vehicle which is capable of a simultaneous co-delivery of therapeutic and diagnostic agents.

Combination of Fluorescence-Guided Surgery With Photodynamic Therapy for the Treatment of Cancer

Specific visualization of body parts is needed during surgery. Fluorescence-guided surgery (FGS) uses a fluorescence contrast agent for in vivo tumor imaging to detect and identify both malignant and normal tissues. There are several advantages and clinical benefits of FGS over other conventional medical imaging modalities, such as its safety, effectiveness, and suitability for real-time imaging in the operating room. Recent advancements in contrast agents and intraoperative fluorescence imaging devices have led to a greater potential for intraoperative fluorescence imaging in clinical applications. Photodynamic therapy (PDT) is an alternative modality to treat tumors, which uses a light-sensitive drug (photosensitizers) and special light to destroy the targeted tissues. In this review, we discuss the fluorescent contrast agents, some newly developed imaging devices, and the successful clinical application of FGS. Additionally, we present the combined strategy of FGS with PDT to further improve the therapeutic effect for patients with cancer. Taken together, this review provides a unique perspective and summarization of FGS.

Quantitative diagnosis of HER2 protein expressing breast cancer by single-particle quantum dot imaging

Overexpression of HER2 is one of the major causes of breast cancer, and therefore precise diagnosis of its protein expression level is important. However, current methods estimating the HER2‐expression level are insufficient due to problem with the lack of quantification. This might result in a gap between diagnostics and therapeutics targeting HER2. Therefore, a new effective diagnostic method is needed. We developed a new immunohistochemical (IHC) technique with quantum dots (QD)‐conjugated trastuzumab using single‐particle imaging to quantitatively measure the HER2 expression level. Tissues from 37 breast cancer patients with available detailed clinical information were tested by IHC with QDs (IHC‐QD) and the correlation with IHC with 3,3′‐diaminobenzidine (DAB), fluorescence in situ hybridization (FISH), and IHC‐QD was examined. The number of QD‐conjugated trastuzumab particles binding specifically to a cancer cell was precisely calculated as the IHC‐QD score. The IHC‐QD score in 37 cases was correlated proportionally with the score of HER2 gene copy number as assessed by FISH (R = 0.83). When HER2 positivity was judged to be positive, the IHC‐QD score with our cut‐off level was exactly concordant with the FISH score with a cut‐off value of 2.0. Furthermore, IHC‐QDs score and time to progression (TTP) of trastuzumab therapy were well correlated in HER2‐positive cases (R = 0.69). Conversely, the correlation between FISH score and TTP was not observed. We developed a precisely quantitative IHC method using trastuzumab‐conjugated QDs and single‐particle imaging analysis and propose the possibility of using IHC‐QDs score as a predictive factor for trastuzumab therapy.

Quantitative detection of the tumor-associated antigen large external antigen in colorectal cancer tissues and cells using quantum dot probe

The large external antigen (LEA) is a cell surface glycoprotein that has been proven to be highly expressed in colorectal cancer (CRC) as a tumor-associated antigen. To evaluate and validate the relationship between LEA expression and clinical characteristics of CRC with high efficiency, LEA expression levels were detected in 85 tissue blocks from CRC patients by quantum dot-based immunohistochemistry (QD-IHC) combined with imaging quantitative analysis using quantum dots with a 605 nm emission wavelength (QD605) conjugated to an ND-1 monoclonal antibody against LEA as a probe. Conventional IHC was performed in parallel for comparison. Both QD-IHC and conventional IHC showed that LEA was specifically expressed in CRC, but not in non-CRC tissues, and high LEA expression was significantly associated with a more advanced T-stage (P<0.05), indicating that LEA is likely to serve as a CRC prognostic marker. Compared with conventional IHC, receiver operating characteristic analysis revealed that QD-IHC possessed higher sensitivity, resulting in an increased positive detection rate of CRC, from 70.1% to 89.6%. In addition, a simpler operation, objective analysis of results, and excellent repeatability make QD-IHC an attractive alternative to conventional IHC in clinical practice. Furthermore, to explore whether the QD probes can be utilized to quantitatively detect living cells or single cells, quantum dot-based immunocytochemistry (QD-ICC) combined with imaging quantitative analysis was developed to evaluate LEA expression in several CRC cell lines. It was demonstrated that QD-ICC could also predict the correlation between LEA expression and the T-stage characteristics of the cell lines, which was confirmed by flow cytometry. The results of this study indicate that QD-ICC has the potential to noninvasively detect rare circulating tumor cells in clinical samples in real clinical applications.

Design and Synthesis of Near-Infrared Peptide for in Vivo Molecular Imaging of HER2

We report the development, characterization, and validation of a peptide specific for the extracellular domain of HER2. This probe chemistry was developed for molecular imaging by using a structural model to select an optimal combination of amino acids that maximize the likelihood for unique hydrophobic and hydrophilic interactions with HER2 domain 3. The sequence KSPNPRF was identified and conjugated with either FITC or Cy5.5 via a GGGSK linker using Fmoc-mediated solid-phase synthesis to demonstrate flexibility for this chemical structure to be labeled with different fluorophores. A scrambled sequence was developed for control by altering the conformationally rigid spacer and moving both hydrophobic and hydrophilic amino acids on the C-terminus. We validated peptide specificity for HER2 in knockdown and competition experiments using human colorectal cancer cells in vitro, and measured a binding affinity of kd = 21 nM and time constant of k = 0.14 min(-1) (7.14 min). We used this peptide with either topical or intravenous administration in a preclinical model of colorectal cancer to demonstrate specific uptake in spontaneous adenomas and to show feasibility for real time in vivo imaging with near-infrared fluorescence. We used this peptide in immunofluorescence studies of human proximal colon specimens to evaluate specificity for sessile serrated and sporadic adenomas. Improved visualization can be used endoscopically to guide tissue biopsy and detect premalignant lesions that would otherwise be missed. Our peptide design for specificity to HER2 is promising for clinical translation in molecular imaging methods for early cancer detection.

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.

Quantum dots-based tissue and in vivo imaging in breast cancer researches: current status and future perspectives

As the most common malignant tumor for females, breast cancer (BC) is a highly heterogeneous disease regarding biological behaviors. Precisely targeted imaging on BC masses and biomarkers is critical to BC detection, treatment, monitoring, and prognostic evaluation. As an important imaging technique, quantum dots (QDs)-based imaging has emerged as a promising tool in BC researches owe to its outstanding optical properties. However, few reviews have been specifically devoted to discussing applications of QDs-based imaging in BC researches. This review summarized recent promising works in QDs-based tissue and in vivo imaging for BC studies. Physicochemical and optical properties of QDs and its potential applications were briefly described first. Then QDs-based imaging studies in BC were systematically reviewed, including tissue imaging for studying biomarkers interactions, and evaluating prognostic biomarkers, in vivo imaging for mapping axillary lymphatic system, showing BC xenograft tumor, and detecting BC metastases. At last, the future perspectives with special emphasis on the potential clinical applications have also been discussed. Potential applications of QDs-based imaging on clinical BC in the future are mainly focused on tissue study, especially in BC molecular pathology due to its optimal optical properties and quantitative information capabilities on multiple biomarkers.

Cancer immunotherapy: nanodelivery approaches for immune cell targeting and tracking

Cancer is one of the most common diseases afflicting people globally. New therapeutic approaches are needed due to the complexity of cancer as a disease. Many current treatments are very toxic and have modest efficacy at best. Increased understanding of tumor biology and immunology has allowed the development of specific immunotherapies with minimal toxicity. It is important to highlight the performance of monoclonal antibodies, immune adjuvants, vaccines and cell-based treatments. Although these approaches have shown varying degrees of clinical efficacy, they illustrate the potential to develop new strategies. Targeted immunotherapy is being explored to overcome the heterogeneity of malignant cells and the immune suppression induced by both the tumor and its microenvironment. Nanodelivery strategies seek to minimize systemic exposure to target therapy to malignant tissue and cells. Intracellular penetration has been examined through the use of functionalized particulates. These nano-particulate associated medicines are being developed for use in imaging, diagnostics and cancer targeting. Although nano-particulates are inherently complex medicines, the ability to confer, at least in principle, different types of functionality allows for the plausible consideration these nanodelivery strategies can be exploited for use as combination medicines. The development of targeted nanodelivery systems in which therapeutic and imaging agents are merged into a single platform is an attractive strategy. Currently, several nanoplatform-based formulations, such as polymeric nanoparticles, micelles, liposomes and dendrimers are in preclinical and clinical stages of development. Herein, nanodelivery strategies presently investigated for cancer immunotherapy, cancer targeting mechanisms and nanocarrier functionalization methods will be described. We also intend to discuss the emerging nano-based approaches suitable to be used as imaging techniques and as cancer treatment options.