Selective uptake and imaging of aptamer- and antibody-conjugated hollow nanospheres targeted to epidermal growth factor receptors overexpressed in head and neck cancer

Synthesis, Characterization and Biosafety Evaluation of Hollow Gold Nanospheres

OBJECTIVES

In order to assess the biosafety of HAuNS using zebrafish models and the cancer cell lines HepG2, HEK293, and A549, this study prepared HAuNS in a variety of sizes and alterations.

METHODS

By oxidizing cobalt nanoparticles encased in gold shells, HAuNS were created. In the meantime, PEG- and PEI-coated HAuNS were created. The diameters of the HAuNS that were produced were 30~40 nm, 50~60 nm, and 70~80 nm. MTT assay was used to assess the toxicity of HAuNS on HepG2, HEK293, and A549 cells. For the investigation of their toxicities, HAuNS (50~60 nm) of various concentrations were incubated with zebrafish embryos. Then, cell death was determined using acridine orange staining.

RESULTS

In a cell line model, it was demonstrated that purified HAuNS exhibit lower toxicity than unpurified HAuNS. Meanwhile, it was discovered that surface-modified HAuNS was less hazardous than unmodified HAuNS. Unpurified HAuNS (50.60 nm) exposure to embryos caused deformity and increased mortality. Moreover, embryos exposed to HAuNS displayed an increase in cell death, showing that HAuNS can put zebrafish under physiological stress.

CONCLUSION

The possible toxicity of HAuNS is now more understood thanks to this investigation. The details could improve our comprehension of the nanotoxicity of medication delivery systems. Comparing HAuNS (50~60 nm) to the other two particle sizes, its toxicity was quite low. Compared to unpurified HAuNS, purified HAuNS displayed less toxicity. Comparing PEI-HAuNS and HAuNS to PEG-HAuNS, cytotoxicity was found to be lower. Our data support the use of pure HAuNS, HAuNS-PEG, and HAuNS (50~60 nm) as possible photothermal conductors when seen as a whole.

A comprehensive review of cancer therapies mediated by conjugated gold nanoparticles with nucleic acid

Nucleic acids provide a promising therapeutic platform by targeting various cell signaling pathways involved in cancer and genetic disorders. However, maintaining optimal stability during delivery limits their utility. Nucleic acid delivery vehicles are generally categorized into biological and synthetic carriers. Regardless of the efficiency of biological vectors, such as viral vectors, issues related to their immunogenicity and carcinogenesis are very important and vital for clinical applications. On the other hand, synthetic vectors such as lipids or polymers, have been widely used for nucleic acid delivery. Despite their transfection efficiency, low storage stability, targeting inefficiency, and tracking limitations are among the limitations of the clinical application of these vectors. In the past decades, gold nanoparticles with unique properties have been shown to be highly efficient mineral vectors for overcoming these obstacles. In this review, we focus on gold nanoparticle-nucleic acid combinations and highlight their use in the treatment of various types of cancers. Furthermore, by stating the biological applications of these structures, we will discuss their clinical applications.

Advanced Techniques in Head and Neck Cancer Imaging: Guide to Precision Cancer Management

Precision treatment requires precision imaging. With the advent of various advanced techniques in head and neck cancer treatment, imaging has become an integral part of the multidisciplinary approach to head and neck cancer care from diagnosis to staging and also plays a vital role in response evaluation in various tumors. Conventional anatomic imaging (CT scan, MRI, ultrasound) remains basic and focuses on defining the anatomical extent of the disease and its spread. Accurate assessment of the biological behavior of tumors, including tumor cellularity, growth, and response evaluation, is evolving with recent advances in molecular, functional, and hybrid/multiplex imaging. Integration of these various advanced diagnostic imaging and nonimaging methods aids understanding of cancer pathophysiology and provides a more comprehensive evaluation in this era of precision treatment. Here we discuss the current status of various advanced imaging techniques and their applications in head and neck cancer imaging.

Application of aptamer functionalized nanomaterials in targeting therapeutics of typical tumors

Cancer is a major cause of human death all over the world. Traditional cancer treatments include surgery, radiotherapy, chemotherapy, immunotherapy, and hormone therapy. Although these conventional treatment methods improve the overall survival rate, there are some problems, such as easy recurrence, poor treatment, and great side effects. Targeted therapy of tumors is a hot research topic at present. Nanomaterials are essential carriers of targeted drug delivery, and nucleic acid aptamers have become one of the most important targets for targeted tumor therapy because of their high stability, high affinity, and high selectivity. At present, aptamer-functionalized nanomaterials (AFNs), which combine the unique selective recognition characteristics of aptamers with the high-loading performance of nanomaterials, have been widely studied in the field of targeted tumor therapy. Based on the reported application of AFNs in the biomedical field, we introduce the characteristics of aptamer and nanomaterials, and the advantages of AFNs first. Then introduce the conventional treatment methods for glioma, oral cancer, lung cancer, breast cancer, liver cancer, colon cancer, pancreatic cancer, ovarian cancer, and prostate cancer, and the application of AFNs in targeted therapy of these tumors. Finally, we discuss the progress and challenges of AFNs in this field.

Progress of Nanomaterials-Based Photothermal Therapy for Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the top 15 most prevalent cancers worldwide. However, the current treatment models for OSCC (e.g., surgery, chemotherapy, radiotherapy, and combination therapy) present several limitations: damage to adjacent healthy tissue, possible recurrence, low efficiency, and severe side effects. In this context, nanomaterial-based photothermal therapy (PTT) has attracted extensive research attention. This paper reviews the latest progress in the application of biological nanomaterials for PTT in OSCC. We divide photothermal nanomaterials into four categories (noble metal nanomaterials, carbon-based nanomaterials, metal compounds, and organic nanomaterials) and introduce each category in detail. We also mention in detail the drug delivery systems for PTT of OSCC and briefly summarize the applications of hydrogels, liposomes, and micelles. Finally, we note the challenges faced by the clinical application of PTT nanomaterials and the possibility of further improvement, providing direction for the future research of PTT in OSCC treatment.

Structure-function relationships in polymeric multilayer capsules designed for cancer drug delivery

The targeted delivery of cancer drugs to tumor-specific molecular targets represents a major challenge in modern personalized cancer medicine. Engineering of micron and submicron polymeric multilayer capsules allows the obtaining of multifunctional theranostic systems serving as controllable stimulus-responsive tools with a high clinical potential to be used in cancer therapy and detection. The functionalities of such theranostic systems are determined by the design and structural properties of the capsules. This review (1) describes the current issues in designing cancer cell-targeting polymeric multilayer capsules, (2) analyzes the effects of the interactions of the capsules with the cellular and molecular constituents of biological fluids, and (3) presents the key structural parameters determining the effectiveness of capsule targeting. The influence of the morphological and physicochemical parameters and the origin of the structural components and surface ligands on the functional activity of polymeric multilayer capsules at the molecular, cellular, and whole-body levels are summarized. The basic structural and functional principles determining the future trends of theranostic capsule development are established and discussed.

Imaging of Clear Cell Renal Carcinoma with Immune Checkpoint Targeting Aptamer-Based Probe

Immune checkpoint targeting immunotherapy has revolutionized the treatment of certain cancers in the recent years. Determination of the status of immune checkpoint expression in particular cancers may assist decision making. Here, we describe the development of a single-stranded aptamer-based molecular probe specifically recognizing human PD-L1. Target engaging aptamers are selected by iterative enrichment from a random ssDNA pool and the binding is characterized biochemically. Specificity and dose dependence is demonstrated in vitro in the cell culture using human kidney tumor cells (786-0), human melanoma cells (WM115 and WM266.4) and human glioblastoma LN18 cancer cells. The utility of the probe in vivo is demonstrated using two mouse tumor models, where we show that the probe exhibits excellent potential in imaging. We postulate that further development of the probe may allow universal imaging of different types of tumors depending on their PD-L1 status, which may find utility in cancer diagnosis.

Carboxylated chitosan-mediated improved efficacy of mesoporous silica nanoparticle-based targeted drug delivery system for breast cancer therapy

Nanoparticle-based targeting of overexpressed cell-surface receptors is a promising strategy that provides precise delivery of drugs to cancer cells. In the present study, we developed highly reproducible and monodispersed, chitosan-coated (pH-responsive), doxorubicin-loaded, aptamer-mesoporous silica nanoparticle (MSN) bioconjugates for actively targeting breast cancer cells harboring overexpression of EGF receptors (EGFR/HER2). The developed targeted MSNs demonstrated higher uptake and cytotoxicity of triple negative and HER2 positive breast cancer cells when compared to non-targeted MSNs. The chitosan coating imparted pH-responsiveness and endo/lysosomal escape ability to MSNs, which augmented cytosolic delivery of an anticancer drug. Partial carboxylation of chitosan coated on MSNs allowed for a greater release of drug in a shorter duration of time while retaining pH-responsiveness and endo/lysosomal escape ability. Overall, the coating of carboxylated-chitosan over MSNs enabled tunable drug release kinetics, conjugation of aptamers (targeting agents), and endo/lysosomal escape which together significantly enhanced the efficacy of the developed drug delivery system.

State of the Art in Gold Nanoparticle Synthesisation via Pulsed Laser Ablation in Liquid and Its Characterisation for Molecular Imaging: A Review

With recent advances in nanotechnology, various nanomaterials have been used as drug carriers in molecular imaging for the treatment of cancer. The unique physiochemical properties and biocompatibility of gold nanoparticles have developed a breakthrough in molecular imaging, which allows exploration of gold nanoparticles in drug delivery for diagnostic purpose. The conventional gold nanoparticles synthetisation methods have limitations with chemical contaminations during the synthesisation process and the use of higher energy. Thus, various innovative approaches in gold nanoparticles synthetisation are under development. Recently, studies have been focused on the development of eco-friendly, non-toxic, cost-effective and simple gold nanoparticle synthesisation. The pulsed laser ablation in liquid (PLAL) technique is a versatile synthetic and convincing technique due to its high efficiency, eco-friendly and facile method to produce gold nanoparticle. Therefore, this study aimed to review the eco-friendly gold nanoparticle synthesisation method via the PLAL method and to characterise the gold nanoparticles properties for molecular imaging. This review paper provides new insight to understand the PLAL technique in producing gold nanoparticles and the PLAL parameters that affect gold nanoparticle properties to meet the desired needs in molecular imaging.

O-carboxymethyl chitosan based pH/hypoxia-responsive micelles relieve hypoxia and induce ROS in tumor microenvironment

The hypoxia in tumor microenvironment (TME) can upregulate the HIF-1α and PD-L1 expression and cause immunosuppression of tumor. In this study, a carboxymethyl chitosan-based pH/hypoxia-responsive and γ-Fe₂O₃/isosorbide dinitrate carrying micelle was designed, and it could catalyze endogenous H₂O₂ to generate oxygen and relieve hypoxia in TME, so as to relieve the overexpression of HIF-1α and PD-L1 in tumor; meanwhile, it could react with H₂O₂ to release ROS via Fenton reaction and induce cytotoxicity in tumor. Along with these multiple effects, this carboxymethyl chitosan-based micelles could provide a comprehensive strategy for tumor treatment.

A comparative analysis of cell surface targeting aptamers

Aptamers represent a potentially important class of ligands for the development of diagnostics and therapeutics. However, it is often difficult to compare the function and specificity of many of these molecules as assay formats and conditions vary greatly. Here, with an interest in developing aptamer targeted therapeutics that could effectively deliver cargoes to cells, we chemically synthesize 15 aptamers that have been reported to target cell surface receptors or cells. Using standardized assay conditions, we assess each aptamer’s binding properties on a panel of 11 different cancer cell lines, correlate aptamer binding to antibody controls and use siRNA transfection to validate each aptamer’s binding to reported target receptors. Using a subset of these molecules known to be expressed on prostate cancers, we use near-infrared in vivo imaging to assess the tumor localization following intravenous injection. Our data demonstrate some surprising differences in the reported specificity and function for many of these molecules and raise concerns regarding their cell targeting capabilities. They also identify an anti-human transferrin aptamer, Waz, as a robust candidate for targeting prostate cancers and for future development of aptamer-based therapeutics.

Aptamers could potentially be widely used in therapy and diagnostics. Here the authors use standardised assay conditions to compare aptamer properties in tumour targeting.

Selection and Characterization of Vimentin-Binding Aptamer Motifs for Ovarian Cancer

The application of aptamers in biomedicine is emerging as an essential technology in the field of cancer research. As small single-stranded DNA or RNA ligands with high specificity and low immunogenicity for their targets, aptamers provide many advantages in cancer therapeutics over protein-based molecules, such as antibodies. Vimentin is an intermediate filament protein that is overexpressed in endothelial cells of cancerous tissue. High expression levels of vimentin have been associated with increased capacity for migration and invasion of the tumor cells. We have selected and identified thioated aptamers with high specificity for vimentin using human ovarian cancer tissues. Tentative binding motifs were chosen for two vimentin aptamers based on predicted secondary structures. Each of these shorter, tentative binding motifs was synthesized, purified, and characterized via cell binding assays. Two vimentin binding motifs with high fidelity binding were selected and further characterized via cell and tissue binding assays, as well as flow cytometric analysis. The equilibrium binding constants of these small thioated aptamer constructs were also determined. Future applications for the vimentin binding aptamer motifs include conjugation of the aptamers to synthetic dyes for use in targeted imaging and therapy, and ultimately more detailed and precise monitoring of treatment response and tumor progression in ovarian pathology.

RNA Aptamers for Theranostics of Glioblastoma of Human Brain

Conventional approaches for studying and molecular typing of tumors include PCR, blotting, omics, immunocytochemistry, and immunohistochemistry. The last two methods are the most used, as they enable detecting both tumor protein markers and their localizations within the cells. In this study, we have investigated a possibility of using RNA aptamers, in particular, 2'-F-pyrimidyl-RNA aptamer ME07 (48 nucleotides long), specific to the receptor of epidermal growth factor (EGFR, ErbB1, Her1), as an alternative to monoclonal antibodies for aptacytochemistry and aptahistochemistry for human glioblastoma multiforme (GBM). A specificity of binding of FAM-ME07 to the receptor on the tumor cells has been demonstrated by flow cytometry; an apparent dissociation constant for the complex of aptamer - EGFR on the cell has been determined; a number of EGFR molecules has been semi-quantitatively estimated for the tumor cell lines having different amount of EGFR: A431 (10⁶ copies per cell), U87 (10⁴ copies per cell), MCF7 (10³ copies per cell), and ROZH, primary GBM cell culture derived from patient (10⁴ copies per cell). According to fluorescence microscopy, FAM-ME07 interacts directly with the receptors on A431 cells, followed by its internalization into the cytoplasm and translocation to the nucleolus; this finding opens a possibility of ME07 application as an escort aptamer for a delivery of therapeutic agents into tumor cells. FAM-ME07 efficiently stains sections of GBM clinical specimens, which enables an identification of EGFR-positive clones within a heterogeneous tumor; and providing a potential for further studying animal models of GBM.

Thermostability, Tunability, and Tenacity of RNA as Rubbery Anionic Polymeric Materials in Nanotechnology and Nanomedicine-Specific Cancer Targeting with Undetectable Toxicity

RNA nanotechnology is the bottom-up self-assembly of nanometer-scale architectures, resembling LEGOs, composed mainly of RNA. The ideal building material should be (1) versatile and controllable in shape and stoichiometry, (2) spontaneously self-assemble, and (3) thermodynamically, chemically, and enzymatically stable with a long shelf life. RNA building blocks exhibit each of the above. RNA is a polynucleic acid, making it a polymer, and its negative-charge prevents nonspecific binding to negatively charged cell membranes. The thermostability makes it suitable for logic gates, resistive memory, sensor set-ups, and NEM devices. RNA can be designed and manipulated with a level of simplicity of DNA while displaying versatile structure and enzyme activity of proteins. RNA can fold into single-stranded loops or bulges to serve as mounting dovetails for intermolecular or domain interactions without external linking dowels. RNA nanoparticles display rubber- and amoeba-like properties and are stretchable and shrinkable through multiple repeats, leading to enhanced tumor targeting and fast renal excretion to reduce toxicities. It was predicted in 2014 that RNA would be the third milestone in pharmaceutical drug development. The recent approval of several RNA drugs and COVID-19 mRNA vaccines by FDA suggests that this milestone is being realized. Here, we review the unique properties of RNA nanotechnology, summarize its recent advancements, describe its distinct attributes inside or outside the body and discuss potential applications in nanotechnology, medicine, and material science.

Targeted molecular imaging of head and neck squamous cell carcinoma: a window into precision medicine

Tumor biomarkers play important roles in tumor growth, invasion, and metastasis. Imaging of specific biomarkers will help to understand different biological activities, thereby achieving precise medicine for each head and neck squamous cell carcinoma (HNSCC) patient. Here, we describe various molecular targets and molecular imaging modalities for HNSCC imaging. An extensive search was undertaken in the PubMed database with the keywords including “HNSCC,” “molecular imaging,” “biomarker,” and “multimodal imaging.” Imaging targets in HNSCC consist of the epidermal growth factor receptor, cluster of differentiation 44 variant 6 (CD44v6), and mesenchymal-epithelial transition factor and integrins. Targeted molecular imaging modalities in HNSCC include optical imaging, ultrasound, magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography. Making the most of each single imaging method, targeted multimodal imaging has a great potential in the accurate diagnosis and therapy of HNSCC. By visualizing tumor biomarkers at cellular and molecular levels in vivo, targeted molecular imaging can be used to identify specific genetic and metabolic aberrations, thereby accelerating personalized treatment development for HNSCC patients.

Assessing the capacity for mental manipulation in patients with statically-determined mild cognitive impairment using digital technology

Aims: Prior research employing a standard backward digit span test has been successful in operationally defining neurocognitive constructs associated with the Fuster’s model of executive attention. The current research sought to test if similar behavior could be obtained using a cross-modal mental manipulation test. Methods: Memory clinic patients were studied. Using Jak-Bondi criteria, 24 patients were classified with mild cognitive impairment (MCI), and 33 memory clinic patients did not meet criteria for MCI (i.e. non-MCI). All patients were assessed with the digital version of the WRAML-2 Symbolic Working Memory Test-Part 1, a cross-modal mental manipulation task where patients hear digits, but respond by touching digits from lowest to highest on an answer key. Only 4 and 5-span trials were analyzed. Using an iPad, all test stimuli were played; and, all responses were obtained with a touch key. Only correct trials were analyzed. Average time to complete trials and latency for each digit was recorded. Results: Groups did not differ when average time to complete 4-span trials was calculated. MCI patients displayed slower latency, or required more time to re-order the 1st and 3rd digits. Regression analyses, primarily involving initial and latter response latencies, were associated with better, but different underlying neuropsychological abilities. Almost no 5-span analyses were significant. Conclusions: This cross-modal test paradigm found no difference for total average time. MCI patients generated slower 1st and 3rd response latency, suggesting differences in time allocation to achieve correct serial order recall. Moreover, different neuropsychological abilities were associated with different time-based test components. These data extend prior findings using a standard backward digit span test. Differences in time epochs are consistent with constructs underlying the model of executive attention and help explain mental manipulation deficits in MCI. These latency measures could constitute neurocognitive biomarkers that track emergent disease.

Aptamers and antibodies: rivals or allies in cancer targeted therapy?

The goal of an efficacious cancer therapy is to specifically target diseased cells at high accuracy while sparing normal, healthy cells. Over the past three decades, immunotherapy, based on the use of monoclonal antibodies (mAbs) directed against tumor-associated antigens, to inhibit their oncogenic function, or against immune checkpoints, to modulate specific T cell responses against cancer, has proven to be an important strategy for cancer therapy. Nevertheless, the number of mAbs approved for clinical use is still limited because of significant drawbacks to their applicability. Oligonucleotide aptamers, similarly to antibodies, form high-affinity bonds with their specific protein targets, thus representing an effective tool for active cancer targeting. Compared to antibodies, aptamers’ use as therapeutic agents benefits from their low size, low/no immunogenicity, simple synthesis and design flexibility for improving efficacy and stability. This review intends to highlight recently emerged applications of aptamers as recognition elements, from biomarker discovery to targeted drug delivery and targeted treatment, showing aptamers’ potential to work in conjunction with antibodies for attacking cancer from multiple flanks.

Research Progress and Prospect of Nanoplatforms for Treatment of Oral Cancer

Oral cancers refer to malignant tumors associated with high morbidity and mortality, and oral squamous cell carcinoma accounts for the majority of cases. It is an important part of head and neck, and oral cancer is one of the six most common cancers in the world. At present, the traditional treatment methods for oral cancer include surgery, radiation therapy, and chemotherapy. However, these methods have many disadvantages. In recent years, nanomedicine, the delivery of drugs through nanoplatforms for the treatment of cancer, has become a promising substitutive therapy. The use of nanoplatforms can reduce the degradation of the drug in the body and accurately deliver it to the tumor site. This minimizes the distribution of the drug to other organs, thereby reducing its toxicity and allowing higher drug concentration at the tumor site. This review introduces polymer nanoparticles, lipid-based nanoparticles, metal nanoparticles, hydrogels, exosomes, and dendrimers for the treatment of oral cancer, and discusses how these nanoplatforms play an anti-cancer effect. Finally, the review gives a slight outlook on the future prospects of nanoplatforms for oral cancer treatment.

Hollow micro and nanostructures for therapeutic and imaging applications

Hollow particles have been extensively used in bioanalytical and biomedical applications for almost two decades due to their unique and tunable optoelectronic properties as well as their significantly high loading capacities. These intrinsic properties led them to be used in various bioimaging applications as contrast agents, controlled delivery (i.e. drugs, nucleic acids and other biomolecules) platforms and photon-triggered therapies (e.g. photothermal and photodynamic therapies). Since recent studies showed that imaging-guided targeted therapeutics have higher success rates, multimodal theranostic platforms (combination of one or more therapy and diagnosis modality) have been employed more often and hollow particles (i.e. nanoshells) have been one of the most efficient candidates to be used in multiple-purpose platforms, owing to their intrinsic properties that enable synergistic multimodal performance. In this review, recent advances in the applications of such hollow particles fabricated with various routes (either inorganic or organic based) were summarized to delineate strategies for tuning their properties for more efficient biomedical performance by overcoming common biological barriers. This review will pave the ways for expedited progress in design of next generation of hollow particles for clinical applications.

DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

Activation Strategies in Image-Guided Nanotherapeutic Delivery

Therapeutic nanomaterials serve as an important platform for drug delivery under image guidance. Despite significant growth and broad applications, their design specifics remain a subject of continued interest primarily due to multifunctional factors involved, ranging from nanomaterial properties, imaging modalities, and therapeutic agents to activation strategies. This review article summarizes key findings on their design characteristics with a particular interest in strategies developed for therapeutic activation (release). First, their activation can be controlled using either an endogenous factor including low pH and glutathione or an external stimulation by light, ultrasound, or electromagnetic field. The former is passively controlled from a spatiotemporal aspect compared to the latter, which is otherwise actively controlled through drug linker photolysis, nanomaterial disassembly, or gate opening. Second, light stimulation serves a most notable strategy due to its essential role in controlled drug release, photothermal activation (hyperthermia), and photodynamic production of reactive oxygen species (ROS). Third, some of those activation strategies that rely on ultrasound, photothermal, photoacoustic, magnetic field, or X-ray radiation are dually functional due to their role in imaging modalities. In summary, this review article presents recent advances and new insights that pertain to nanotherapeutic delivery systems. It also addresses their technical limitations associated with tissue penetration (light), spatial resolution (ultrasound, hyperthermia), and occurrence of cellular resistance (ROS).

Photodynamic therapy, priming and optical imaging: Potential co-conspirators in treatment design and optimization - a Thomas Dougherty Award for Excellence in PDT paper

Photodynamic therapy is a photochemistry-based approach, approved for the treatment of several malignant and non-malignant pathologies. It relies on the use of a non-toxic, light activatable chemical, photosensitizer, which preferentially accumulates in tissues/cells and, upon irradiation with the appropriate wavelength of light, confers cytotoxicity by generation of reactive molecular species. The preferential accumulation however is not universal and, depending on the anatomical site, the ratio of tumor to normal tissue may be reversed in favor of normal tissue. Under such circumstances, control of the volume of light illumination provides a second handle of selectivity. Singlet oxygen is the putative favorite reactive molecular species although other entities such as nitric oxide have been credibly implicated. Typically, most photosensitizers in current clinical use have a finite quantum yield of fluorescence which is exploited for surgery guidance and can also be incorporated for monitoring and treatment design. In addition, the photodynamic process alters the cellular, stromal, and/or vascular microenvironment transiently in a process termed photodynamic priming, making it more receptive to subsequent additional therapies including chemo- and immunotherapy. Thus, photodynamic priming may be considered as an enabling technology for the more commonly used frontline treatments. Recently, there has been an increase in the exploitation of the theranostic potential of photodynamic therapy in different preclinical and clinical settings with the use of new photosensitizer formulations and combinatorial therapeutic options. The emergence of nanomedicine has further added to the repertoire of photodynamic therapy's potential and the convergence and co-evolution of these two exciting tools is expected to push the barriers of smart therapies, where such optical approaches might have a special niche. This review provides a perspective on current status of photodynamic therapy in anti-cancer and anti-microbial therapies and it suggests how evolving technologies combined with photochemically-initiated molecular processes may be exploited to become co-conspirators in optimization of treatment outcomes. We also project, at least for the short term, the direction that this modality may be taking in the near future.

Aptamers with Tunable Affinity Enable Single-Molecule Tracking and Localization of Membrane Receptors on Living Cancer Cells

Tumor cell-surface markers are usually overexpressed or mutated protein receptors for which spatiotemporal regulation differs between and within cancers. Single-molecule fluorescence imaging can profile individual markers in different cellular contexts with molecular precision. However, standard single-molecule imaging methods based on overexpressed genetically encoded tags or cumbersome probes can significantly alter the native state of receptors. We introduce a live-cell points accumulation for imaging in nanoscale topography (PAINT) method that exploits aptamers as minimally invasive affinity probes. Localization and tracking of individual receptors are based on stochastic and transient binding between aptamers and their targets. We demonstrated single-molecule imaging of a model tumor marker (EGFR) on a panel of living cancer cells. Affinity to EGFR was finely tuned by rational engineering of aptamer sequences to define receptor motion and/or native receptor density.

Nucleic Acid Aptamers for Molecular Diagnostics and Therapeutics: Advances and Perspectives

The advent of SELEX (systematic evolution of ligands by exponential enrichment) technology has shown the ability to evolve artificial ligands with affinity and specificity able to meet growing clinical demand for probes that can, for example, distinguish between the target leukemia cells and other cancer cells within the matrix of heterogeneity, which characterizes cancer cells. Though antibodies are the conventional and ideal choice as a molecular recognition tool for many applications, aptamers complement the use of antibodies due to many unique advantages, such as small size, low cost, and facile chemical modification. This Minireview will focus on the novel applications of aptamers and SELEX, as well as opportunities to develop molecular tools able to meet future clinical needs in biomedicine.

Hyperthermia and smart drug delivery systems for solid tumor therapy

Chemotherapy is a cornerstone of cancer therapy. Irrespective of the administered drug, it is crucial that adequate drug amounts reach all cancer cells. To achieve this, drugs first need to be absorbed, then enter the blood circulation, diffuse into the tumor interstitial space and finally reach the tumor cells. Next to chemoresistance, one of the most important factors for effective chemotherapy is adequate tumor drug uptake and penetration. Unfortunately, most chemotherapeutic agents do not have favorable properties. These compounds are cleared rapidly, distribute throughout all tissues in the body, with only low tumor drug uptake that is heterogeneously distributed within the tumor. Moreover, the typical microenvironment of solid cancers provides additional hurdles for drug delivery, such as heterogeneous vascular density and perfusion, high interstitial fluid pressure, and abundant stroma. The hope was that nanotechnology will solve most, if not all, of these drug delivery barriers. However, in spite of advances and decades of nanoparticle development, results are unsatisfactory. One promising recent development are nanoparticles which can be steered, and release content triggered by internal or external signals. Here we discuss these so-called smart drug delivery systems in cancer therapy with emphasis on mild hyperthermia as a trigger signal for drug delivery.

Pyrene-Modified DNA Aptamers with High Affinity to Wild-Type EGFR and EGFRvIII

Nucleic acid aptamers have been proven to be a useful tool in many applications. Particularly, aptamers to epidermal growth factor receptor (EGFR) have been successfully used for the recognition of EGFR-expressing cells, the inhibition of EGFR-dependent pathways, and targeted drug delivery into EGFR-positive cells. Several aptamers are able to discriminate wild-type EGFR from its mutant form, EGFRvIII. Aptamers to EGFR have hairpin-like secondary structures with several possible folding variations. Here, an aptamer, previously selected to EGFRvIII, was chosen as a lead compound for extensive post-SELEX maturation. The aptamer was 1.5-fold truncated, the ends of the hairpin stem were appended with GC-pairs to increase thermal stability, and single pyrene modification was introduced into the aptamer to increase affinity to the target protein. Pyrene modification was selected from extensive computer docking studies of a library of thousands of chemicals to EGFR near the EGF-binding interface. The resulting aptamers bound extracellular domains of both variants of EGFR: EGFRwt and EGFRvIII with subnanomolar apparent dissociation constants. Compared with the initial aptamer, affinity to EGFRwt was increased up to 7.5-fold, whereas affinity to EGFRvIII was increased up to 4-fold.

An anticancer agent-loaded PLGA nanomedicine with glutathione-response and targeted delivery for the treatment of lung cancer

Stimuli response or controlled release is a new research hotspot in nanomedicine; however, there is scarce research on organic nanomedicines with stimuli responses, which limits their practical biological applications. In addition, homoharringtonine (HHT) has been used as an effective anticancer agent, but reducing its toxicity and side effects is an urgent problem to be solved. Herein, an EGFR (epidermal growth factor receptor) aptamer-modified HHT-loaded PLGA-SS-PEG nanomedicine was developed. The nanomaterial possesses spherical morphology and admirable biocompatibility. After targeted endocytosis in tumour cells via the selective recognition between EGFR and its aptamer, the PLGA nanomedicine is triggered by a high GSH level and releases its cargo in lung cancer cells. The in vitro and in vivo results reveal that the PLGA nanomedicine not only inhibited the proliferation and promoted the apoptosis of lung cancer cells, but also possessed better therapeutic efficacy and less toxic side effects compared with the free anticancer agent. Consequently, this study provides a novel approach to construct a biodegradable nanomedicine with targeted recognition and stimuli response. Moreover, it inhibited the proliferation of lung cancer cells with high efficiency and low toxicity. Importantly, the PLGA nanomedicine demonstrates encouraging potential as a multifunctional nano-system applicable for cancer therapy.

Stimuli-responsive nanoparticle-assisted immunotherapy: a new weapon against solid tumours

The interplay between photo-thermal therapy and immunotherapy allows the realization of new nanotechnology-based cancer treatments for solid tumors.

Advanced Nanotechnology Leading the Way to Multimodal Imaging-Guided Precision Surgical Therapy

Surgical resection is the primary and most effective treatment for most patients with solid tumors. However, patients suffer from postoperative recurrence and metastasis. In the past years, emerging nanotechnology has led the way to minimally invasive, precision and intelligent oncological surgery after the rapid development of minimally invasive surgical technology. Advanced nanotechnology in the construction of nanomaterials (NMs) for precision imaging-guided surgery (IGS) as well as surgery-assisted synergistic therapy is summarized, thereby unlocking the advantages of nanotechnology in multimodal IGS-assisted precision synergistic cancer therapy. First, mechanisms and principles of NMs to surgical targets are briefly introduced. Multimodal imaging based on molecular imaging technologies provides a practical method to achieve intraoperative visualization with high resolution and deep tissue penetration. Moreover, multifunctional NMs synergize surgery with adjuvant therapy (e.g., chemotherapy, immunotherapy, phototherapy) to eliminate residual lesions. Finally, key issues in the development of ideal theranostic NMs associated with surgical applications and challenges of clinical transformation are discussed to push forward further development of NMs for multimodal IGS-assisted precision synergistic cancer therapy.

Probing the biological obstacles of nanomedicine with gold nanoparticles

Despite massive growth in nanomedicine research to date, the field still lacks fundamental understanding of how certain physical and chemical features of a nanoparticle affect its ability to overcome biological obstacles in vivo and reach its intended target. To gain fundamental understanding of how physical and chemical parameters affect the biological outcomes of administered nanoparticles, model systems that can systematically manipulate a single parameter with minimal influence on others are needed. Gold nanoparticles are particularly good model systems in this case as one can synthetically control the physical dimensions and surface chemistry of the particles independently and with great precision. Additionally, the chemical and physical properties of gold allow particles to be detected and quantified in tissues and cells with high sensitivity. Through systematic biological studies using gold nanoparticles, insights toward rationally designed nanomedicine for in vivo imaging and therapy can be obtained. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Molecular Engineering of Functional Nucleic Acid Nanomaterials toward In Vivo Applications

Recent advances in nanotechnology and engineering have generated many nanomaterials with unique physical and chemical properties. Over the past decade, numerous nanomaterials are introduced into many research areas, such as sensors for environmental monitoring, food safety, point-of-care diagnostics, and as transducers for solar energy transfer. Meanwhile, functional nucleic acids (FNAs), including nucleic acid enzymes, aptamers, and aptazymes, have attracted major attention from the biomedical community due to their unique target recognition and catalytic properties. Benefiting from the recent progress of molecular engineering strategies, the physicochemical properties of nanomaterials are endowed by the target recognition and catalytic activity of FNAs in the presence of a target analyte, resulting in numerous smart nanoprobes for diverse applications including intracellular imaging, drug delivery, in vivo imaging, and tumor therapy. This progress report focuses on the recent advances in designing and engineering FNA-based nanomaterials, highlighting the functional outcomes toward in vivo applications. The challenges and opportunities for the future translation of FNA-based nanomaterials into clinical applications are also discussed.

Targeting strategies for improving the efficacy of nanomedicine in oncology

The use of nanoparticles as drug carriers has provided a powerful weapon in the fight against cancer. These nanocarriers are able to transport drugs that exhibit very different nature such as lipophilic or hydrophilic drugs and big macromolecules as proteins or RNA. Moreover, the external surface of these carriers can be decorated with different moieties with high affinity for specific membrane receptors of the tumoral cells to direct their action specifically to the malignant cells. The selectivity improvement yielded by these nanocarriers provided a significative enhancement in the efficacy of the transported drug, while the apparition of side effects in the host was reduced. Additionally, it is possible to incorporate targeting moieties selective for organelles of the cell, which improves even more the effect of the transported agents. In the last years, more sophisticated strategies such as the use of switchable, hierarchical or double targeting strategies have been proposed for overcoming some of the limitations of conventional targeting strategies. In this review, recent advances in the development of targeted nanoparticles will be described with the aim to present the current state of the art of this technology and its huge potential in the oncological field.

Studies on effectiveness of PTT on 3D tumor model under microfluidic conditions using aptamer-modified nanoshells

Herein, we present the research focused on the synthesis and application of aptamer-modified gold nanoshells for photothermal therapy (PTT). NIR-absorbing hollow gold nanoshells were synthetized and conjugated with anti-MUC1 aptamer (HGNs@anti-MUC1). MUC1 (Mucin 1) is a transmembrane glycoprotein, which is overexpressed in a variety of epithelial cancers (eg. breast, lung, pancreatic). In order to evaluate the efficiency of PTT with HGNs@anti-MUC1 we used 3D cell culture model - multicellular spheroids. The selected cell culture model is considered as the best in vitro model for cancer research (similar morphology, metabolite and oxygen gradients, cellular interactions and cell growth kinetics in the spheroids are similar to the early stage of a nonvascular tumor). We conducted our research on human normal (MRC-5, MCF-10A) and tumor (A549, MCF-7) cell lines using a microfluidic system. Aptamer-modified nanoparticles were accumulated selectively in tumor cells (A549, MCF-7) and this fact contributed to the reduction of tumor spheroids viability and size. It should be underlined, that it is the first example of photothermal therapy carried out in a microsystem on multicellular spheroids.

Staphylococcus aureus-mimetic control of antibody orientation on nanoparticles

We designed a bacterio-mimetic nanoparticle that can noncovalently control the orientation of attached antibodies. Liposomes with Fc-binding peptide (FcBP), formulated using FcBP-conjugated PEGylated lipid, were used as model nanoparticles. Compared with control nanoparticles surface-modified with antibody covalently attached via maleimide functional groups (Mal-NPs), FcBP-capped nanoparticles (FcBP-NPs) exhibited greater binding affinity to the target protein. Human epidermal growth factor receptor 2 (HER2)-specific antibody-modified FcBP-NPs (HER2/FcBP-NPs) showed 5.3-fold higher binding affinity to HER2 than isotype IgG antibody-modified NPs, and 2.6-fold higher affinity compared with anti-HER2 antibody-conjugated Mal-NPs. Cellular uptake of HER2/FcBP-NPs in HER2-positive cells was significantly higher than that of other formulations. The biodistribution of HER2/FcBP-NPs was higher than that of antibody-conjugated NPs in HER2-positive tumor tissues, but not in HER2-negative tumors. Our findings suggest the potential of bacteriomimetic nanoparticles for controlling the orientation of antibody attachment. These nanoparticles may have diverse applications in nanomedicine, including drug delivery, molecular imaging, and diagnosis.

Targeting HMGA protein inhibits retinoblastoma cell proliferation

We describe a novel synthetic strategy for conjugating HMGA2 siRNA and the HMGA aptamer to the nucleolin aptamer and nucleolin antibody, respectively. Our studies demonstrate that these conjugates inhibit cell proliferation in retinoblastoma cells.

A novel approach to target HMGA proteins in retinoblastoma using HMGA2 siRNA–nucleolin aptamer and HMGA aptamer–nucleolin antibody conjugates was developed.

Application of aptamers for in vivo molecular imaging and theranostics

Nucleic acid aptamers are small three-dimensional structures of oligonucleotides selected to bind to a target of interest with high affinity and specificity. In vitro, aptamers already compete with antibodies to serve as imaging probes, e.g. for microscopy or flow cytometry. However, they are also increasingly used for in vivo molecular imaging. Accordingly, aptamers have been evaluated over the last twenty years in almost every imaging modality, including single photon emission computed tomography, positron emission tomography, magnetic resonance imaging, fluorescence imaging, echography, and x-ray computed tomography. This review focuses on the studies that were conducted in vivo with aptamer-based imaging probes. It also presents how aptamers have been recently used to develop new types of probes for multimodal imaging and theranostic applications.

Nanomaterial-involved neural stem cell research: Disease treatment, cell labeling, and growth regulation

Neural stem cells (NSCs) have been widely investigated for their potential in the treatment of various diseases and transplantation therapy. However, NSC growth regulation, labeling, and its application to disease diagnosis and treatment are outstanding challenges. Recently, nanomaterials have shown promise for various applications including genetic modification, imaging, and controlled drug release. Here we summarize the recent progress in the use of nanomaterials in combination with NSCs for disease treatment and diagnosis, cell labeling, and NSC growth regulation. The toxicity of nanomaterials to NSCs is also discussed.

PET imaging of EGFR expression using an 18F-labeled RNA aptamer

OBJECTIVE

Epidermal growth factor receptor (EGFR) is a theranostic biomarker for a variety of cancer types. The aim of the present study was to develop an ¹⁸F radiolabeled EGFR targeting RNA aptamer, and to investigate its ability to visualize and quantify EGFR in xenograft models.

METHODS

Biolayer interferometry binding assay was used to detect the binding affinity of the alkyne-modified EGFR aptamer MinE07 (denoted as ME07) with recombinant human wild-type EGFR protein and the mutant EGFRvIII protein. Cy5-conjugated ME07 was used for flow cytometry and immunofluorescence staining, and an Alexa Fluor 488-labeled EGFR antibody (ab193244) was used as a control. ¹⁸F-Fluorobenzoyl (FB) azide was employed as a synthon to produce ¹⁸F-FB-ME07 via click chemistry, and the cellular uptake and internalization characteristics of ¹⁸F-FB-ME07 were investigated. Static PET scans, 60-min dynamic scans, and biodistribution study of ¹⁸F-FB-ME07 were performed in three types of tumor models.

RESULTS

The K_d values of ME07 to wtEGFR and EGFRvIII proteins were 0.3 nM and 271 nM respectively. The A431, U87MG, and HCT-116 cells showed strong, weak, and negative binding with Cy5-ME07, which is consistent with EGFR expression level in these cells. Peak cell uptake values of ¹⁸F-FB-ME07 in A431, U87MG and HCT-116 cells were 2.86%, 2.19% and 0.88% of the added dose respectively. The mean internalization of ¹⁸F-FB-ME07 in these cells were 60.02%, 53.1%, and 52.8% of the total accumulated radioactivity. In static PET imaging, despite high uptake in the liver and kidneys, ¹⁸F-FB-ME07 showed reasonable accumulation in A431 tumors (1.02 ± 0.13 %ID/g at 30 min after injection). Of note, the uptake of ¹⁸F-FB-ME07 in A431 xenografts was significantly higher than that in U87MG and HCT-116 xenografts. In A431 xenografted mice, the tumor/blood ratio was 3.89 and the tumor/muscle ratio reached 8.65.

CONCLUSIONS

We for the first time generated an aptamer-derived EGFR targeting PET tracer ¹⁸F-FB-ME07, which showed highly selective targeting ability in mouse tumor models expressing different levels of EGFR. Our results suggest that ¹⁸F-FB-ME07 is a potential EGFR targeting molecular imaging probe for future clinical translation.

Next-Generation DNA-Functionalized Quantum Dots as Biological Sensors

DNA-functionalized quantum dots (DNA-QDs) have found considerable application in biosensing and bioimaging. Different from the first generation (I-G) DNA-QDs prepared via conventional bioconjugation chemistry, the second generation (II-G) DNA-QDs prepared via one-step DNA-templated QD synthesis features a defined number of DNA valencies (usually monovalency), which is preferable for controlled assembly and biological targeting. In this review, we summarize recent progress in designing QD probes based on II-G DNA-QDs for advanced sensing and imaging applications. It opens up new avenues for highly sensitive and intelligent sensing of a range of disease-relevant biomolecules in vitro and in living cells.

Targeted Molecular Imaging Using Aptamers in Cancer

Imaging is not only seeing, but also believing. For targeted imaging modalities, nucleic acid aptamers have features such as superior recognition of structural epitopes and quick uptake in target cells. This explains the emergence of an evolved new class of aptamers into a wide spectrum of imaging applications over the last decade. Genetically encoded biosensors tagged with fluorescent RNA aptamers have been developed as intracellular imaging tools to understand cellular signaling and physiology in live cells. Cancer-specific aptamers labeled with fluorescence have been used for assessment of clinical tissue specimens. Aptamers conjugated with gold nanoparticles have been employed to develop innovative mass spectrometry tissue imaging. Also, use of chemically conjugated cancer-specific aptamers as probes for non-invasive and high-resolution imaging has been transformative for in vivo imaging in multiple cancers.

Utilizing Peptide Ligand GPCRs to Image and Treat Pancreatic Cancer

It is estimated that early detection of pancreatic ductal adenocarcinoma (PDAC) could increase long-term patient survival by as much as 30% to 40% (Seufferlein, T. et al., Nat. Rev. Gastroenterol. Hepatol.2016, 13, 74–75). There is an unmet need for reagents that can reliably identify early cancerous or precancerous lesions through various imaging modalities or could be employed to deliver anticancer treatments specifically to tumor cells. However, to date, many PDAC tumor-targeting strategies lack selectivity and are unable to discriminate between tumor and nontumor cells, causing off-target effects or unclear diagnoses. Although a variety of approaches have been taken to identify tumor-targeting reagents that can effectively direct therapeutics or imaging agents to cancer cells (Liu, D. et al., J. Controlled Release2015, 219, 632–643), translating these reagents into clinical practice has been limited, and it remains an area open to new methodologies and reagents (O’Connor, J.P. et al., Nat. Rev. Clin. Oncol. 2017, 14, 169–186). G protein–coupled receptors (GPCRs), which are key target proteins for drug discovery and comprise a large proportion of currently marketed therapeutics, hold significant promise for tumor imaging and targeted treatment, particularly for pancreatic cancer.