In vivo imaging of brain cancer using epidermal growth factor single domain antibody bioconjugated to near-infrared quantum dots

Antibody Conjugated Nano-Enabled Drug Delivery Systems Against Brain Tumors

The use of antibody-conjugated nanoparticles for brain tumor treatment has gained significant attention in recent years. Nanoparticles functionalized with anti-transferrin receptor antibodies have shown promising results in facilitating nanoparticle uptake by endothelial cells of brain capillaries and post-capillary venules. This approach offers a potential alternative to the direct conjugation of biologics to antibodies. Furthermore, studies have demonstrated the potential of antibody-conjugated nanoparticles in targeting brain tumors, as evidenced by the specific binding of these nanoparticles to brain cancer cells. Additionally, the development of targeted nanoparticles designed to transcytoses the blood-brain barrier (BBB) to deliver small molecule drugs and therapeutic antibodies to brain metastases holds promise for brain tumor treatment. While the use of nanoparticles as a delivery method for brain cancer treatment has faced challenges, including the successful delivery of nanoparticles to malignant brain tumors due to the presence of the BBB and infiltrating cancer cells in the normal brain, recent advancements in nanoparticle-mediated drug delivery systems have shown potential for enhancing the efficacy of brain cancer therapy. Moreover, the development of brain-penetrating nanoparticles capable of distributing over clinically relevant volumes when administered via convection-enhanced delivery presents a promising strategy for improving drug delivery to brain tumors. In conclusion, the use of antibody-conjugated nanoparticles for brain tumor treatment shows great promise in overcoming the challenges associated with drug delivery to the brain. By leveraging the specific targeting capabilities of these nanoparticles, researchers are making significant strides in developing effective and targeted therapies for brain tumors.

vNARs as Neutralizing Intracellular Therapeutic Agents: Glioblastoma as a Target

Glioblastoma is the most prevalent and fatal form of primary brain tumors. New targeted therapeutic strategies for this type of tumor are imperative given the dire prognosis for glioblastoma patients and the poor results of current multimodal therapy. Previously reported drawbacks of antibody-based therapeutics include the inability to translocate across the blood-brain barrier and reach intracellular targets due to their molecular weight. These disadvantages translate into poor target neutralization and cancer maintenance. Unlike conventional antibodies, vNARs can permeate tissues and recognize conformational or cryptic epitopes due to their stability, CDR3 amino acid sequence, and smaller molecular weight. Thus, vNARs represent a potential antibody format to use as intrabodies or soluble immunocarriers. This review comprehensively summarizes key intracellular pathways in glioblastoma cells that induce proliferation, progression, and cancer survival to determine a new potential targeted glioblastoma therapy based on previously reported vNARs. The results seek to support the next application of vNARs as single-domain antibody drug-conjugated therapies, which could overcome the disadvantages of conventional monoclonal antibodies and provide an innovative approach for glioblastoma treatment.

Methods of miRNA delivery and possibilities of their application in neuro-oncology

In the current phase of medical progress, practical neuro-oncology faces critical challenges. These include the quest for and development of innovative methodological approaches, as well as the enhancement of conventional therapies to boost their efficacy in treating brain tumors, especially the malignant varieties. Recent strides in molecular and cellular biology, molecular genetics, and immunology have charted the primary research pathways in the development of new anti-cancer medications, with a particular focus on microRNA (miRNA)-based therapy. MiRNAs possess the ability to function as suppressors of tumor growth while also having the potential to act as oncogenes. MiRNAs wield control over numerous processes within the human body, encompassing tumor growth, proliferation, invasion, metastasis, apoptosis, angiogenesis, and immune responses. A significant impediment to enhancing the efficacy of brain tumor treatment lies in the unresolved challenge of traversing the blood-brain barrier (BBB) and blood-tumor barrier (BTB) to deliver therapeutic agents directly to the tumor tissue. Presently, there is a worldwide effort to conduct intricate research and design endeavors aimed at creating miRNA-based dosage forms and delivery systems that can effectively target various structures within the central nervous system (CNS). MiRNA-based therapy stands out as one of the most promising domains in neuro-oncology. Hence, the development of efficient and safe methods for delivering miRNA agents to the specific target cells within brain tumors is of paramount importance. In this study, we will delve into recent findings regarding various methods for delivering miRNA agents to brain tumor cells. We will explore the advantages and disadvantages of different delivery systems and consider some clinical aspects of miRNA-based therapy for brain tumors.

Progress and Challenges in the Diagnosis and Treatment of Brain Cancer Using Nanotechnology

Primary brain cancer or brain cancer is the overgrowth of abnormal or malignant cells in the brain or its nearby tissues that form unwanted masses called brain tumors. People with malignant brain tumors suffer a lot, and the expected life span of the patients after diagnosis is often only around 14 months, even with the most vigorous therapies. The blood-brain barrier (BBB) is the main barrier in the body that restricts the entry of potential chemotherapeutic agents into the brain. The chances of treatment failure or low therapeutic effects are some significant drawbacks of conventional treatment methods. However, recent advancements in nanotechnology have generated hope in cancer treatment. Nanotechnology has shown a vital role starting from the early detection, diagnosis, and treatment of cancer. These tiny nanomaterials have great potential to deliver drugs across the BBB. Beyond just drug delivery, nanomaterials can be simulated to generate fluorescence to detect tumors. The current Review discusses in detail the challenges of brain cancer treatment and the application of nanotechnology to overcome those challenges. The success of chemotherapeutic treatment or the surgical removal of tumors requires proper imaging. Nanomaterials can provide imaging and therapeutic benefits for cancer. The application of nanomaterials in the diagnosis and treatment of brain cancer is discussed in detail by reviewing past studies.

Quantum dots: The cutting-edge nanotheranostics in brain cancer management

Quantum dots (QDs) are semiconductor nanocrystals possessing unique optoelectrical properties in that they can emit light energy of specific tunable wavelengths when excited by photons. They are gaining attention nowadays owing to their all-around ability to allow high-quality bio-imaging along with targeted drug delivery. The most lethal central nervous system (CNS) disorders are brain cancers or malignant brain tumors. CNS is guarded by the blood-brain barrier which poses a selective blockade toward drug delivery into the brain. QDs have displayed strong potential to deliver therapeutic agents into the brain successfully. Their bio-imaging capability due to photoluminescence and specific targeting ability through the attachment of ligand biomolecules make them preferable clinical tools for coming times. Biocompatible QDs are emerging as nanotheranostic tools to identify/diagnose and selectively kill cancer cells. The current review focuses on QDs and associated nanoformulations as potential futuristic clinical aids in the continuous battle against brain cancer.

Versatile Application of Nanobodies for Food Allergen Detection and Allergy Immunotherapy

The unique characteristics of camelid heavy-chain only antibody (HCAb) derived nanobodies (Nbs) have facilitated their employment as tools for research and application in extensive fields including food safety inspection, diagnosis and therapy of diseases, etc., to develop immune detecting techniques or alternative candidates of conventional antibodies as diagnostic and therapeutic reagents. The wide application in the fields of food allergen inspection and immunotherapy has not been addressed as not much results published in the literature. The robust properties and straightforward selecting strategy of Nbs impel the advantageous employment compared with monoclonal antibodies (mAbs) to establish immunoassay and serve as blocking antibodies to compete immunoglobulin E (IgE) binding epitopes on food allergens. More and more efforts have been invested to develop specific Nbs against food allergen proteins, such as macadamia allergen of Mac i 1, peanut allergen of Ara h 3, and lupine allergen of Lup an 1, which demonstrated the potential of Nbs for research and application in food allergen surveillance. Meanwhile, the paratopes of Nbs preferably targeting the unique epitopes of food allergens can provide more possibilities to serve as blocking antibodies to shield IgE binding epitopes for food allergy immunotherapy. Regardless, the research and application of Nbs in the field of food allergen and allergic reactions are expected to attract dramatic focus and produce promising research outputs.

Nanobodies as molecular imaging probes

Camelidae derived single-domain antibodies (sdAbs), commonly known as nanobodies (Nbs), are the smallest antibody fragments with full antigen-binding capacity. Owing to their desirable properties such as small size, high specificity, strong affinity, excellent stability, and modularity, nanobodies are on their way to overtake conventional antibodies in terms of popularity. To date, a broad range of nanobodies have been generated against different molecular targets with applications spanning basic research, diagnostics, and therapeutics. In the field of molecular imaging, nanobody-based probes have emerged as a powerful tool. Radioactive or fluorescently labeled nanobodies are now used to detect and track many targets in different biological systems using imaging techniques. In this review, we provide an overview of the use of nanobodies as molecular probes. Additionally, we discuss current techniques for the generation, conjugation, and intracellular delivery of nanobodies.

Diagnosis of Glioblastoma by Immuno-Positron Emission Tomography

Simple Summary

Neuroimaging has transformed the way brain tumors are diagnosed and treated. Although different non-invasive modalities provide very helpful information, in some situations, they present a limited value. By merging the specificity of antibodies with the resolution, sensitivity, and quantitative capabilities of positron emission tomography (PET), “Immuno-PET” allows us to conduct the non-invasive diagnosis and monitoring of patients over time using antibody-based probes as an in vivo, integrated, quantifiable, 3D, full-body “immunohistochemistry”, like a “virtual biopsy”. This review provides and focuses on immuno-PET applications and future perspectives of this promising imaging approach for glioblastoma.

Abstract

Neuroimaging has transformed neuro-oncology and the way that glioblastoma is diagnosed and treated. Magnetic Resonance Imaging (MRI) is the most widely used non-invasive technique in the primary diagnosis of glioblastoma. Although MRI provides very powerful anatomical information, it has proven to be of limited value for diagnosing glioblastomas in some situations. The final diagnosis requires a brain biopsy that may not depict the high intratumoral heterogeneity present in this tumor type. The revolution in “cancer-omics” is transforming the molecular classification of gliomas. However, many of the clinically relevant alterations revealed by these studies have not yet been integrated into the clinical management of patients, in part due to the lack of non-invasive biomarker-based imaging tools. An innovative option for biomarker identification in vivo is termed “immunotargeted imaging”. By merging the high target specificity of antibodies with the high spatial resolution, sensitivity, and quantitative capabilities of positron emission tomography (PET), “Immuno-PET” allows us to conduct the non-invasive diagnosis and monitoring of patients over time using antibody-based probes as an in vivo, integrated, quantifiable, 3D, full-body “immunohistochemistry” in patients. This review provides the state of the art of immuno-PET applications and future perspectives on this imaging approach for glioblastoma.

A comprehensive comparison between camelid nanobodies and single chain variable fragments

By the emergence of recombinant DNA technology, many antibody fragments have been developed devoid of undesired properties of natural immunoglobulins. Among them, camelid heavy-chain variable domains (VHHs) and single-chain variable fragments (scFvs) are the most favored ones. While scFv is used widely in various applications, camelid antibodies (VHHs) can serve as an alternative because of their superior chemical and physical properties such as higher solubility, stability, smaller size, and lower production cost. Here, these two counterparts are compared in structure and properties to identify which one is more suitable for each of their various therapeutic, diagnosis, and research applications.

Galectins in Glioma: Current Roles in Cancer Progression and Future Directions for Improving Treatment

Simple Summary

Glioblastomas are among the most common and aggressive brain tumors. The high rate of recurrence and mortality associated with this cancer underscores the need for the development of new therapeutical targets. Galectins are among the new targets that have attracted the attention of many scientists working in the field of cancer. They form a group of small proteins found in many tissues where they accomplish various physiological roles, including regulation of immune response and resistance to cell death. In many types of cancer, however, production of abnormally high levels of galectins by cancer cells can be detrimental to patients. Elevated levels of galectins can, for example, suppress the ability of the host’s immune system to kill cancer cells. They can also provide cancer cells with resistance to drugs-induced cell death. Here, we review the recent progress that has contributed to a better understanding of the mechanisms of actions of galectins in glioblastoma. We also discuss recent development of anti-galectin drugs and the challenges associated with their use in clinical settings, with particular attention to their role in reducing the efficacy of immunotherapy, a promising treatment that exploits the capacity of the immune system to recognize and kill cancer cells.

Abstract

Traditional wisdom suggests that galectins play pivotal roles at different steps in cancer progression. Galectins are particularly well known for their ability to increase the invasiveness of cancer cells and their resistance to drug-induced cell death. They also contribute to the development of local and systemic immunosuppression, allowing cancer cells to escape the host’s immunological defense. This is particularly true in glioma, the most common primary intracranial tumor. Abnormally high production of extracellular galectins in glioma contributes to the establishment of a strong immunosuppressive environment that favors immune escape and tumor progression. Considering the recent development and success of immunotherapy in halting cancer progression, it is logical to foresee that galectin-specific drugs may help to improve the success rate of immunotherapy for glioma. This provides a new perspective to target galectins, whose intracellular roles in cancer progression have already been investigated thoroughly. In this review, we discuss the mechanisms of action of galectins at different steps of glioma progression and the potential of galectin-specific drugs for the treatment of glioma.

Camelid Single-Domain Antibodies for the Development of Potent Diagnosis Platforms

The distinct biophysical and pharmaceutical properties of camelid single-domain antibodies, referred to as VHHs or nanobodies, are associated with their nanometric dimensions, elevated stability, and antigen recognition capacity. These biomolecules can circumvent a number of diagnostic system limitations, especially those related to the size and stability of conventional immunoglobulins currently used in enzyme-linked immunosorbent assays and point-of-care, electrochemical, and imaging assays. In these formats, VHHs are directionally conjugated to different molecules, such as metallic nanoparticles, small peptides, and radioisotopes, which demonstrates their comprehensive versatility. Thus, the application of VHHs in diagnostic systems range from the identification of cancer cells to the detection of degenerative disease biomarkers, viral antigens, bacterial toxins, and insecticides. The improvements of sensitivity and specificity are among the central benefits resulting from the use of VHHs, which are indispensable parameters for high-quality diagnostics. Therefore, this review highlights the main biotechnological advances related to camelid single-domain antibodies and their use in in vitro and in vivo diagnostic approaches for human health.

Nanobodies: new avenue to treat kidney disease

Current therapeutic options for renal diseases are limited, and the search for disease-specific treatments is ongoing. Nanobodies, single-domain antibodies with many advantages over conventional antibodies, provide flexible, easy-to-format biologicals with many possible applications. Here, we discuss the potential use of nanobodies for renal diseases.

Nanobody-A versatile tool for cancer diagnosis and therapeutics

In spite of the successful use of monoclonal antibodies (mAbs) in clinic for tumor treatment, their applications are still hampered in therapeutic development due to limitations, such as tumor penetration and high cost of manufacture. Nanobody, a single domain antibody that holds the strong antigen targeting and binding capacity, has demonstrated various advantages relative to antibody. Nanobody is considered as a next-generation of antibody-derived tool in the antigen related recognition and modulation. A number of nanobodies have been developed and evaluated in different stages of clinical trials for cancer treatment. Here we summarized the current progress of nanobody in tumor diagnosis and therapeutics, particularly on the conjugation of nanobody with functional moieties. The nanobody conjugation of diagnostic agents, such as radionuclide and optical tracers, can achieve specific tumor imaging. The nanobody-drug conjugates can enhance the therapeutic efficacy of anti-tumor drugs and reduce the adverse effects. The decoration of nanobody on nanodrug delivery systems can further improve the drug targeting to specific tumors. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Visualization of Diagnostic and Therapeutic Targets in Glioma With Molecular Imaging

Gliomas, particularly high-grade gliomas including glioblastoma (GBM), represent the most common and malignant types of primary brain cancer in adults, and carry a poor prognosis. GBM has been classified into distinct subgroups over the years based on cellular morphology, clinical characteristics, biomarkers, and neuroimaging findings. Based on these classifications, differences in therapeutic response and patient outcomes have been established. Recently, the identification of complex molecular signatures of GBM has led to the development of diverse targeted therapeutic regimens and translation into multiple clinical trials. Chemical-, peptide-, antibody-, and nanoparticle-based probes have been designed to target specific molecules in gliomas and then be visualized with multimodality molecular imaging (MI) techniques including positron emission tomography (PET), single-photon emission computed tomography (SPECT), near-infrared fluorescence (NIRF), bioluminescence imaging (BLI), and magnetic resonance imaging (MRI). Thus, multiple molecules of interest can now be noninvasively imaged to guide targeted therapies with a potential survival benefit. Here, we review developments in molecular-targeted diagnosis and therapy in glioma, MI of these targets, and MI monitoring of treatment response, with a focus on the biological mechanisms of these advanced molecular probes. MI probes have the potential to noninvasively demonstrate the pathophysiologic features of glioma for diagnostic, treatment, and response assessment considerations for various targeted therapies, including immunotherapy. However, most MI tracers are in preclinical development, with only integrin α_Vβ₃ and isocitrate dehydrogenase (IDH)-mutant MI tracers having been translated to patients. Expanded international collaborations would accelerate translational research in the field of glioma MI.

Physical approaches to treat glioblastoma

PURPOSE OF REVIEW

Glioblastoma (GBM) patients have a poor prognosis despite the use of modern synergistic multimodal treatment strategies, with a progression-free survival estimated at 7-8 months, a median survival of 14-16 months and 5-year overall survival of 9.8%.

RECENT FINDINGS

Physical methods hold the promise to act synergistically with classical treatments to improve the outcome of GBM patients. Fluorescent guided surgery with 5-aminolevulinic acid and tumor-treating fields therapy have already shown positive results in randomized phase III trials and have been incorporated in the standard management. Other techniques such as photodynamic therapy (PDT) and focused ultrasound, often combined whit microbubbles, are reaching clinical development.

SUMMARY

Several clinical trials to evaluate the feasibility and efficacy of ultrasound devices to disrupt the blood-brain barrier are ongoing. PDT enables the creation of a safety margin or treatment of non-resecable tumors. However, randomized trials are urgently required to validate the efficacy of these promising approaches. We aim to critically review physical approaches to treat GBM, focusing on available clinical trial data.

Nanobodies: Next Generation of Cancer Diagnostics and Therapeutics

The development of targeted medicine has greatly expanded treatment options and spurred new research avenues in cancer therapeutics, with monoclonal antibodies (mAbs) emerging as a prevalent treatment in recent years. With mixed clinical success, mAbs still hold significant shortcomings, as they possess limited tumor penetration, high manufacturing costs, and the potential to develop therapeutic resistance. However, the recent discovery of “nanobodies,” the smallest-known functional antibody fragment, has demonstrated significant translational potential in preclinical and clinical studies. This review highlights their various applications in cancer and analyzes their trajectory toward their translation into the clinic.

A review of applications of principles of quantum physics in oncology: do quantum physics principles have any role in oncology research and applications?

Background:

Research in the applications of the principles of quantum physics in oncology has progressed significantly over the past decades; and several research groups with professionals from diverse scientific background, including electrical engineers, mathematicians, biologists, atomic physicists, computer programmers, and biochemists, are working collaboratively in an unprecedented and pioneering economic, organisational and human effort searching for a wider and more effective, potentially definitive, understanding of the cancers. It is hypothesised that the principles of quantum physics could open new and broader understanding of the cancers and the development of new effective, targeted, accurate, personalised and possibly definitive cancer treatment.

Materials and methods:

This paper reports on a review of recent studies in the field of the applications of the principles of quantum physics in biology, chemistry, biochemistry and quantum physics in cancer research, including quantum physics principles and cancer, quantum modelling techniques, quantum dots and its applications in oncology, quantum cascade laser histopathology and quantum computing applications.

Conclusions:

The applications of the principles of quantum physics in oncology, chemistry and biology are providing new perspectives and greater insights into a long-studied disease, which could result in a greater understanding of the cancers and the potential for personalised and definitive treatment methods.

Intraoperative fluorescence diagnosis in the brain: a systematic review and suggestions for future standards on reporting diagnostic accuracy and clinical utility

Background

Surgery for gliomas is often confounded by difficulties in distinguishing tumor from surrounding normal brain. For better discrimination, intraoperative optical imaging methods using fluorescent dyes are currently being explored. Understandably, such methods require the demonstration of a high degree of diagnostic accuracy and clinical benefit. Currently, clinical utility is determined by tissue biopsies which are correlated to optical signals, and quantified using measures such as sensitivity, specificity, positive predictive values, and negative predictive values. In addition, surgical outcomes, such as extent of resection rates and/or survival (progression-free survival (PFS) and overall survival (OS)) have been measured. These assessments, however, potentially involve multiple biases and confounders, which have to be minimized to ensure reproducibility, generalizability and comparability of test results. Test should aim at having a high internal and external validity. The objective of this article is to analyze how diagnostic accuracy and outcomes are utilized in available studies describing intraoperative imaging and furthermore, to derive recommendations for reliable and reproducible evaluations.

Methods

A review of the literature was performed for assessing the use of measures of diagnostic accuracy and outcomes of intraoperative optical imaging methods. From these data, we derive recommendations for designing and reporting future studies.

Results

Available literature indicates that potential confounders and biases for reporting the diagnostic accuracy and usefulness of intraoperative optical imaging methods are seldom accounted for. Furthermore, methods for bias reduction are rarely used nor reported.

Conclusions

Detailed, transparent, and uniform reporting on diagnostic accuracy of intraoperative imaging methods is necessary. In the absence of such reporting, studies will not be comparable or reproducible. Future studies should consider some of the recommendations given here.

Electronic supplementary material

The online version of this article (10.1007/s00701-019-04007-y) contains supplementary material, which is available to authorized users.

Nanoformulations for glioblastoma multiforme: a new hope for treatment

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults, associated with a high mortality rate and a survival of between 12 and 15 months after diagnosis. Due to current treatment limitations involving surgery, radiotherapy and chemotherapy with temozolamide, there is a high rate of treatment failure and recurrence. To try to overcome these limitations nanotechnology has emerged as a novel alternative. Lipid, polymeric, silica and magnetic nanoparticles, among others, are being developed to improve GBM treatment and diagnosis. These nanoformulations have many advantages, including lower toxicity, biocompatibility and the ability to be directed toward the tumor. This article reviews the progress that have been made and the large variety of nanoparticles currently under study for GBM.

Nanodelivery systems for overcoming limited transportation of therapeutic molecules through the blood-brain barrier

Due to the impermeable structure and barrier function of the blood-brain barrier (BBB), the delivery of therapeutic molecules into the CNS is extremely limited. Nanodelivery systems are regarded as the most effective and versatile carriers for the CNS, as they can transport cargo molecules across the BBB via various mechanisms. This review emphasizes the multi-functionalization strategies of nanodelivery systems and combinatorial approaches for the delivery of therapeutic drugs and genes into the CNS. The characteristics and functions of the BBB and underlying mechanisms of molecular translocation across the BBB are also described.

Interleukin-13 conjugated quantum dots for identification of glioma initiating cells and their extracellular vesicles

Cadmium selenide (CdSe) based quantum dots modified with polyethylene glycol and chemically linked to interleukin-13 (IL13) were prepared with the aim of identifying the high affinity receptor (IL13Rα2) which is expressed in glioma stem cells and exosomes secreted by these cancer stem cells. IL13 conjugated quantum dots (IL13QD) were thoroughly characterized for their physicochemical properties including particle size and surface morphology. Furthermore, the specific binding of the IL13QD to glioma cells and to glioma stem cells (GSC) was verified using a competitive binding study. The exosomes were isolated from the GSC conditioned medium and the expression of IL13Rα2 in the GSC and exosomes was verified. The binding property of IL13QD to the tumor associated exosomes was initially confirmed by transmission electron microscopy. The force of attraction between the quantum dots and U251 glioma cells and the exosomes was investigated by atomic force microscopy, which indicated a higher force of binding interaction between the IL13QD and IL13Rα2 expressing glioma cells and exosomes secreted by glioma stem cells. Flow cytometry of the IL13QD and exosomes from the culture media and cerebrospinal fluid (CSF) of patients with glioma tumors indicated a distinctly populated complex pattern different from that of non-targeted quantum dots and bovine serum albumin (BSA) conjugated quantum dots confirming specific binding potential of the IL13QD to the tumor associated exosomes. The results of this study demonstrate that IL13QD can serve as an ex vivo marker for glioma stem cells and exosomes that can inform diagnosis and prognosis of patients harboring malignant disease.

STATEMENT OF SIGNIFICANCE

Functionalized quantum dots are flexible semiconductor nanomaterials which have an immense application in biomedical research. In particular, when they are functionalized with biomolecules like proteins or antibodies, they have the specialized ability to detect the expression of receptors and antigens in cells and tissues. In this study we designed a cytokine (interleukin-13) functionalized quantum dot to detect a cancer associated receptor expressed in cancer stem cells and the extracellular vesicles (exosomes) secreted by the cancer cells themselves. The binding pattern of these cytokine modified quantum dots to the cancer stem cells and exosomes alters the physical properties of the complex in the fixed and suspended form. This altered binding pattern can be monitored by a variety of techniques, including transmission electron microscopy, atomic force microscopy and flow cytometry, and subsequent characterization of this quantum dot binding profile provides useful data that can be utilized as a fingerprint to detect cancer disease progression. This type of functionalized quantum dot fingerprint is especially useful for invasive cancers including brain and other metastatic cancers and may allow for earlier detection of disease progression or recurrence, thus saving the lives of patients suffering from this devastating disease.

One-Pot Aqueous Synthesization of Near-Infrared Quantum Dots for Bioimaging and Photodynamic Therapy of Gliomas

BACKGROUND

As the early detection and total destruction of gliomas are essential for longer survival, we attempted to synthesize a quantum dot (QD) that is capable of recognizing glioma cells for imaging and photodynamic therapy.

METHODS

Using a one-pot aqueous approach, near infrared-emitting CdTe was produced. After detection of its physicochemical characteriistics, it was conjugated with RGD. The emission images were observed with confocal microscopy. To test its toxicity, CdTe-RGD at various concentrations was separately added to a human glioma cell line (U251) and a mouse embryo fibroblast cell line (3T3) (control) for incubation in dark conditions. To test its photodynamic effect, the U251 and 3T3 cells were then irradiated for 5-60 min, using a 632.8-nm laser.

RESULTS

This QD (Φ = 3.75 nm, photoluminescence (PL) peak wavelength = 700 nm, photoluminescence quantum yield (PLQY) = 20 %), was a spherical crystal with excellent monodispersity. Under a confocal microscope, U251 cells were visualized, but not the 3T3 cells. In dark conditions, the survival rates of both U251 and 3T3 cells were above 85 %. After laser irradiation, the survival rate of U251 cells decreased to 37 ± 1.6 % as the irradiation time and the CdTe-RGD concentration were increased.

CONCLUSIONS

With good physicochemical characteriistics and low toxicity, this QD-RGD has broad prospects for use in the biomedical imaging and photodynamic therapy of gliomas.

Targeting Glioblastoma with the Use of Phytocompounds and Nanoparticles

Glioblastoma multiforme (GBM) are extremely lethal and still poorly treated primary brain tumors, characterized by the presence of highly tumorigenic cancer stem cell (CSC) subpopulations, considered responsible for tumor relapse. In order to successfully eradicate GBM growth and recurrence, new anti-cancer strategies selectively targeting CSCs should be designed. CSCs might be eradicated by targeting some of their cell surface markers and transporters, inducing their differentiation, impacting their hyper-glycolytic metabolism, inhibiting CSC-related signaling pathways and/or by targeting their microenvironmental niche. In this regard, phytocompounds such as curcumin, isothiocyanates, resveratrol and epigallocatechin-3-gallate have been shown to prevent or reverse cancer-related epigenetic dysfunctions, reducing tumorigenesis, preventing metastasis and/or increasing chemotherapy and radiotherapy efficacy. However, the actual bioavailability and metabolic processing of phytocompounds is generally unknown, and the presence of the blood brain barrier often represents a limitation to glioma treatments. Nowadays, nanoparticles (NPs) can be loaded with therapeutic compounds such as phytochemicals, improving their bioavailability and their targeted delivery within the GBM tumor bulk. Moreover, NPs can be designed to increase their tropism and specificity toward CSCs by conjugating their surface with antibodies specific for CSC antigens, with ligands or with glucose analogues. Here we discuss the use of phytochemicals as anti-glioma agents and the applicability of phytochemical-loaded NPs as drug delivery systems to target GBM. Additionally, we provide some examples on how NPs can be specifically formulated to improve CSC targeting.

Optimising electrogenerated chemiluminescence of quantum dots via co-reactant selection

We demonstrate that for quantum dot (QD) based electrochemiluminescence (ECL), the commonly used co-reactant does not perform as effectively as potassium persulfate. By exploiting this small change in co-reactant, ECL intensity can be enhanced dramatically in a cathodic-based ECL system. However, TPA remains the preferential co-reactant-based system for anodic ECL. This phenomenon can be rationalised through the relative energy-level profiles of the QD to the co-reactant in conjunction with the applied potential range. This work highlights the importance of understanding the co-reactant pathway for optimising the application of ECL to bioanalytical analysis, in particular for near-infrared (NIR) QDs which can be utilised for analysis in blood.

Graphical Abstract

Ultrasmall inorganic nanoparticles: State-of-the-art and perspectives for biomedical applications

Ultrasmall nanoparticulate materials with core sizes in the 1-3nm range bridge the gap between single molecules and classical, larger-sized nanomaterials, not only in terms of spatial dimension, but also as regards physicochemical and pharmacokinetic properties. Due to these unique properties, ultrasmall nanoparticles appear to be promising materials for nanomedicinal applications. This review overviews the different synthetic methods of inorganic ultrasmall nanoparticles as well as their properties, characterization, surface modification and toxicity. We moreover summarize the current state of knowledge regarding pharmacokinetics, biodistribution and targeting of nanoscale materials. Aside from addressing the issue of biomolecular corona formation and elaborating on the interactions of ultrasmall nanoparticles with individual cells, we discuss the potential diagnostic, therapeutic and theranostic applications of ultrasmall nanoparticles in the emerging field of nanomedicine in the final part of this review.

Conjugation of biotin-coated luminescent quantum dots with single domain antibody-rhizavidin fusions

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Single domain antibody—rhizavidin fusion bioconjugated biotin coated quantum dots.

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Provided facile and effective method to orient antibodies on QD surface.

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Accomplished improved production of His-tagged rhizavidin (RZh) in E. coli.

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Demonstrated utility of RZh as a replacement for tetrameric biotin binders.

Straightforward and effective methods are required for the bioconjugation of proteins to surfaces and particles. Previously we demonstrated that the fusion of a single domain antibody with the biotin binding molecule rhizavidin provided a facile method to coat biotin-modified surfaces with a highly active and oriented antibody. Here, we constructed similar single domain antibody—rhizavidin fusions as well as unfused rhizavidin with a His-tag. The unfused rhizavidin produced efficiently and its utility for assay development was demonstrated in surface plasmon resonance experiments. The single domain antibody-rhizavidin fusions were utilized to coat quantum dots that had been prepared with surface biotins. Preparation of antibody coated quantum dots by this means was found to be both easy and effective. The prepared single domain antibody-quantum dot reagent was characterized by surface plasmon resonance and applied to toxin detection in a fluoroimmunoassay sensing format.

Aptamer for imaging and therapeutic targeting of brain tumor glioblastoma

Aptamers are short single-stranded nucleic acids (RNA or ssDNA), identified by an in vitro selection process, denominated SELEX, from a partially random oligonucleotide library. They bind to a molecular target, a protein or other complex macromolecular structures of interest with high affinity and specificity, comparable to those of antibodies. Recently, aptamer selection protocols were developed for targeting living cells, including tumors. Chemical modifications of the aptamers and modalities of their detection and delivery systems are already available with high selectivity and targeting ability for the desired cancer cell type, making them promising for diagnosis and therapy. Glioblastoma multiformae represents the most malignant and fatal stage of glioma, and is also the most frequent brain tumor. Glioblastoma-specific aptamers were developed by either targeting the whole cell surface or known glioma biomarkers. These aptamers may gain importance for imaging, tumor cell isolation from biopsies and drug delivery. In biomedical imaging techniques, aptamers coupled with radionuclide or fluorescent labels, bioconjugates and nanoparticles offer an advanced, noninvasive manner for defining the glioblastoma tissue border. Though single modality aptamer imaging probes have some limitations, these are overcome by the use of multimodal probes. Due to selectivity and chemical characteristics, aptamers can be coupled to functionalized nanoparticles and loaded with a drug, appeared promising for in vivo targeting of glioblastoma. Finally, aptamers are effective mediators for gene silencing when coupled to small interfering RNA and a viral vector, thus providing a novel tool with enhanced targeting capability in drug delivery, designed for tailored treatment of glioblastoma patients.

Aqueous phase synthesis of highly luminescent, nitrogen-doped carbon dots and their application as bioimaging agents

Carbon dots are promising scaffolds for multifunctional therapeutic systems because of their fluorescence property, good biocompatibility, and low toxicity. In this work, we prepared nitrogen-doped carbon dots through an aqueous phase strategy using folic acid as precursor. The carbon dots possess many attractive features including uniform dispersion with size about 9 nm, bright photoluminescence, high photoluminescence quantum yield of 23%, and low toxicity, making them excellent imaging probes for biomedical applications.

Convergence of nanotechnology and cancer prevention: are we there yet?

Nanotechnology is emerging as a promising modality for cancer treatment; however, in the realm of cancer prevention, its full utility has yet to be determined. Here, we discuss the potential of integrating nanotechnology in cancer prevention to augment early diagnosis, precision targeting, and controlled release of chemopreventive agents, reduced toxicity, risk/response assessment, and personalized point-of-care monitoring. Cancer is a multistep, progressive disease; the functional and acquired characteristics of the early precancer phenotype are intrinsically different from those of a more advanced anaplastic or invasive malignancy. Therefore, applying nanotechnology to precancers is likely to be far more challenging than applying it to established disease. Frank cancers are more readily identifiable through imaging and biomarker and histopathologic assessment than their precancerous precursors. In addition, prevention subjects routinely have more rigorous intervention criteria than therapy subjects. Any nanopreventive agent developed to prevent sporadic cancers found in the general population must exhibit a very low risk of serious side effects. In contrast, a greater risk of side effects might be more acceptable in subjects at high risk for cancer. Using nanotechnology to prevent cancer is an aspirational goal, but clearly identifying the intermediate objectives and potential barriers is an essential first step in this exciting journey.