Epirubicin loaded super paramagnetic iron oxide nanoparticle-aptamer bioconjugate for combined colon cancer therapy and imaging in vivo

Functionalized liposomes as a potential drug delivery systems for colon cancer treatment: A systematic review

Colon cancer is one of the lethal diseases in the world with approximately 700,000 fatalities annually. Nowadays, due to the side effects of existing methods in the treatment of colon cancer such as radiotherapy and chemotherapy, the use of targeted nanocarriers in cancer treatment has received wide attention, and among them, especially liposomes have been studied a lot. Based on this, anti-tumor drugs hidden in targeted active liposomes can selectively act on cancer cells. In this systematic review, the use of various ligands such as folic acid, transferrin, aptamer, hyaluronic acid and cRGD for active targeting of liposomes to achieve improved drug delivery to colon cancer cells has been reviewed. The original articles published in English in the databases of Science Direct, PubMed and Google scholar from 2012 to 2022 were reviewed. From the total of 26,256 published articles, 19 studies met the inclusion criteria. The results of in vitro and in vivo studies have revealed that targeted liposomes lead to increasing the efficacy of anti-cancer agents on colon cancer cells with reducing side effects compared to free drugs and non-targeted liposomes. To the best of our knowledge, this is the first systematic review showing promising results for improvement treatment of colon cancer using targeted liposomes.

Aptamers as an approach to targeted cancer therapy

Conventional cancer treatments can cause serious side effects because they are not specific to cancer cells and can damage healthy cells. Aptamers often are single-stranded oligonucleotides arranged in a unique architecture, allowing them to bind specifically to target sites. This feature makes them an ideal choice for targeted therapeutics. They are typically produced through the systematic evolution of ligands by exponential enrichment (SELEX) and undergo extensive pharmacological revision to modify their affinity, specificity, and therapeutic half-life. Aptamers can act as drugs themselves, directly inhibiting tumor cells. Alternatively, they can be used in targeted drug delivery systems to transport drugs directly to tumor cells, minimizing toxicity to healthy cells. In this review, we will discuss the latest and most advanced approaches to using aptamers for cancer treatment, particularly targeted therapy overcoming resistance to conventional therapies.

Targeted delivery of epirubicin to cancerous cell using copper sulphide nanoparticle coated with polyarginine and 5TR1 aptamer

Chemotherapy has been widely acknowledged as a primary approach for cancer treatment. However, the administration of chemotherapy agents is often limited by their adverse effects that result from an inability to distinguish between healthy and malignant cells. As such, utilising nanocarriers in targeted drug delivery can significantly reduce these side effects while enhancing therapeutic efficacy. Herein, we developed copper sulphide nanoparticles (CuSNPs) loaded with epirubicin (Epi) coated by polyarginine and 5TR1 aptamer (CEPA) to target mucin-1 which is overexpressed on various types of cancer cells. MTT results revealed that CEPA significantly induced cytotoxicity of the drug in desired cell lines (C26 and MCF-7, mucin+) compared to CEPA-treated CHO cells (non-target, mucin-), verifying the targeting ability of CEPA complex. The obtained results from both flow cytometry analysis and cell imaging demonstrated that CEPA complex had successful internalisation in both target cell lines but no internalisation in CHO cell line. The result of in vivo assay showed more tumour inhibition and more accumulation in tumour tissue for CEPA complex in comparison to free Epi. To conclude, the CEPA complex has demonstrated superior efficacy and fewer adverse reactions compared to Epi. This indicates a promising and effective strategy for treating cancer.

Nanobiotechnology-based strategies in alleviation of chemotherapy-mediated cardiotoxicity

The cardiovascular diseases have been among the most common malignancies and the first leading cause of death, even higher than cancer. The cardiovascular diseases can be developed as a result of cardiac dysfunction and damages to heart tissue. Exposure to toxic agents and chemicals that induce cardiac dysfunction has been of interest in recent years. The chemotherapy drugs are commonly used for cancer therapy and in these patients, cardiovascular diseases have been widely observed that is due to negative impact of chemotherapy drugs on the heart. These drugs increase oxidative damage and inflammation, and mediate apoptosis and cardiac dysfunction. Hence, nanotechnological approaches have been emerged as new strategies in attenuation of chemotherapy-mediated cardiotoxicity. The first advantage of nanoparticles can be explored in targeted and selective delivery of drugs to reduce their accumulation in heart tissue. Nanostructures can deliver bioactive and therapeutic compounds in reducing cardiotoxicity and alleviation toxic impacts of chemotherapy drugs. The functionalization of nanostructures increases their selectivity against tumor cells and reduces accumulation of drugs in heart tissue. The bioplatforms such as chitosan and alginate nanostructures can also deliver chemotherapy drugs and reduce their cardiotoxicity. The function of nanostructures is versatile in reduction of cardiotoxicity by chemotherapy drugs and new kind of platforms is hydrogels that can mediate sustained release of drug to reduce its toxic impacts on heart tissue. The various kinds of nanoplatforms have been developed for alleviation of cardiotoxicity and their future clinical application depends on their biocompatibility. High concentration level of chitosan nanoparticles can stimulate cardiotoxicity. Therefore, if nanotechnology is going to be deployed for drug delivery and reducing cardiotoxicity, the first pre-requirement is to lack toxicity on normal cells and have high biocompatibility.

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.

Aptamer-Based Probes for Cancer Diagnostics and Treatment

Aptamers are single-stranded DNA or RNA oligomers that have the ability to generate unique and diverse tertiary structures that bind to cognate molecules with high specificity. In recent years, aptamer researches have witnessed a huge surge, owing to its unique properties, such as high specificity and binding affinity, low immunogenicity and toxicity, and simplicity of synthesis with negligible batch-to-batch variation. Aptamers may bind to targets, such as various cancer biomarkers, making them applicable for a wide range of cancer diagnosis and treatment. In cancer diagnostic applications, aptamers are used as molecular probes instead of antibodies. They have the potential to detect various cancer-associated biomarkers. For cancer therapeutic purposes, aptamers can serve as therapeutic or delivery agents. The chemical stabilization and modification strategies for aptamers may expand their serum half-life and shelf life. However, aptamer-based probes for cancer diagnosis and therapy still face several challenges for successful clinical translation. A deeper understanding of nucleic acid chemistry, tissue distribution, and pharmacokinetics is required in the development of aptamer-based probes. This review summarizes their application in cancer diagnostics and treatments based on different localization of target biomarkers, as well as current challenges and future prospects.

Functional Nanomaterials in Biomedicine: Current Uses and Potential Applications

Nanomaterials, that is, materials made up of individual units between 1 and 100 nanometers, have lately involved a lot of attention since they offer a lot of potential in many fields, including pharmacy and biomedicine, owed to their exceptional physicochemical properties arising from their high surface area and nanoscale size. Smart engineering of nanostructures through appropriate surface or bulk functionalization endows them with multifunctional capabilities, opening up new possibilities in the biomedical field such as biosensing, drug delivery, imaging, medical implants, cancer treatment and tissue engineering. This article highlights up-to-date research in nanomaterials functionalization for biomedical applications. A summary of the different types of nanomaterials and the surface functionalization strategies is provided. Besides, the use of nanomaterials in diagnostic imaging, drug/gene delivery, regenerative medicine, cancer treatment and medical implants is reviewed. Finally, conclusions and future perspectives are provided.

DNA Nanotechnology-Based Supramolecular Assemblies for Targeted Biomedical Applications

DNA is a polyanionic, hydrophilic, and natural biopolymer that offers properties such as biodegradability, biocompatibility, non-toxicity, and non-immunogenicity. These properties of DNA as an ideal biopolymer offer modern-day researchers' reasons to exploit these to form high-order supramolecular assemblies. These structures could range from simple to complex and provide various applications. Among them, supramolecular assemblies like DNA hydrogels (DNA-HG) and DNA dendrimers (DNA-DS) show massive growth potential in the areas of biomedical applications such as cell biology, medical stream, molecular biology, pharmacology, and healthcare product manufacturing. The application of both of these assemblies has seen enormous growth in recent years. In this focused review on DNA-based supramolecular assemblies like hydrogels and dendrimers, we present the principles of synthesis and characterization, key developments with examples and applications, and conclude with a brief perspective on challenges and future outlook for such devices and their subsequent applications.

Surface Engineering of Nanomaterials with Polymers, Biomolecules, and Small Ligands for Nanomedicine

Nanomedicine is a speedily growing area of medical research that is focused on developing nanomaterials for the prevention, diagnosis, and treatment of diseases. Nanomaterials with unique physicochemical properties have recently attracted a lot of attention since they offer a lot of potential in biomedical research. Novel generations of engineered nanostructures, also known as designed and functionalized nanomaterials, have opened up new possibilities in the applications of biomedical approaches such as biological imaging, biomolecular sensing, medical devices, drug delivery, and therapy. Polymers, natural biomolecules, or synthetic ligands can interact physically or chemically with nanomaterials to functionalize them for targeted uses. This paper reviews current research in nanotechnology, with a focus on nanomaterial functionalization for medical applications. Firstly, a brief overview of the different types of nanomaterials and the strategies for their surface functionalization is offered. Secondly, different types of functionalized nanomaterials are reviewed. Then, their potential cytotoxicity and cost-effectiveness are discussed. Finally, their use in diverse fields is examined in detail, including cancer treatment, tissue engineering, drug/gene delivery, and medical implants.

Biomacromolecule-Functionalized Nanoparticle-Based Conjugates for Potentiation of Anticancer Therapy

Cancer is a rapidly growing life-threatening disease that affected 18.1 million people worldwide in 2018. Various conventional techniques like surgery, radiation, and chemotherapy are considered as a mainstream treatment for patients but show some limitations like cytotoxicity due to off-targeted action, poor intra-tumor localization, development of multi-drug resistance by tumor cells, physical and psychological stresses, etc. Such limitations have motivated the scientists to work towards more patient-centric and precision therapy using advanced drug delivery systems like liposomes, nanoparticles, nanoconjugates, etc. However, these carriers also face limitations like poor biocompatibility, lesser payload capacity, leakage of encapsulated drug, and short-term stability. So, this review article explores the profound insights for the development of biomacromolecule-functionalized nanoconjugates to potentiate the anticancer activity of therapeutic agents for various cancers like lung, colorectal, ovarian, breast and liver cancer. Researchers have shown interest in biofunctionalized nanoconjugates because of advantages like biocompatibility, site-specificity with better localization, higher entrapment with long-term stability and lesser off-target toxicity. The progressive trend of biomacromolecule nanoconjugates will encourage further research for the development of effective transport of drugs, nutraceuticals and phytoconstituents for on-site effect at cancer microenvironment and tumor cells with higher safety profile.

Imaging cancer cells with nanostructures: Prospects of nanotechnology driven non-invasive cancer diagnosis

The application of nanostructured materials in medicine is a rapidly evolving area of research that includes both the diagnosis and treatment of various diseases. Metals, metal oxides and carbon-based nanomaterials have shown much promise in medical technological advancements due to their tunable physical, chemical and biological properties. The nanoscale properties, especially the size, shape, surface chemistry and stability makes them highly desirable for diagnosing and treating various diseases, including cancers. Major applications of nanomaterials in cancer diagnosis include in vivo bioimaging and molecular marker detection, mainly as image contrast agents using modalities such as radio, magnetic resonance, and ultrasound imaging. When a suitable targeting ligand is attached on the nanomaterial surface, it can help pinpoint the disease site during imaging. The application of nanostructured materials in cancer diagnosis can help in the early detection, treatment and patient follow-up . This review aims to gather and present the information regarding the application of nanotechnology in cancer diagnosis. We also discuss the challenges and prospects regarding the application of nanomaterials as cancer diagnostic tools.

Bioconjugated nanometals and cancer therapy: a pharmaceutical perspective

Conventional cancer chemotherapies are associated with challenges like delivering sub-therapeutic doses to target cells, lack of bioavailability, drug insolubility and nonspecific toxicity to healthy cells. Nanomedicine, an advanced process, can contribute to the development of personalized medicine for diagnosis, therapy and monitoring of cancer. The nanometals enhance drug dissolution and adhesion to targeted tumor surfaces, resulting in rapid onset of effective therapeutic action. Moreover, nanometals can be conjugated with ligands or polymers through a conjugation process, which further leads to enhanced efficiency, target specificity, improved pharmacokinetics and pharmacodynamics of the drug. This review focuses on the applications of conjugated nanometals in cancer therapy, with a special focus on noble and magnetic nanometals.

Treating colon cancers with a non-conventional yet strategic approach: An overview of various nanoparticulate systems

Regardless of progress in therapy management which are developed for colon cancer (CC), it remains the third most common cause of mortality due to cancers around the world. Conventional medicines pose side effects due to untoward action on non-target cells. Their inability to deliver drugs to the affected regions of the colon locally, in a reproducible manner raises a concern towards the efficacy of therapy. In this regard, nanoparticles emerged as a promising drug delivery system due to their flexibility in designing, drug release modulation and cancer cell targeting. Not only are nanoparticles making their way into colon cancer research in the revolution of conventional onco-therapeutics, but they also offer promising scope in the development of colon cancer vaccines and theranostic tools. However, there are challenges with respect to drug delivery using nanoparticles, which may hamper the delivery of these novel carriers to the colon. The present review addresses recent advents in nanotechnology for colon-specific drug delivery (CDDS) which may help to overcome the existing challenges and intends to recognize futuristic potentials in the treatment of CC with CDDS.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

Hybrid System for Local Drug Delivery and Magnetic Hyperthermia Based on SPIONs Loaded with Doxorubicin and Epirubicin

Cancer is one of the most common causes of death worldwide, thus new solutions in anticancer therapies are highly sought after. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anticancer drugs are synthesized and investigated as potential magnetic drug nanocarriers for local drug delivery and mild magnetic hyperthermia. We have obtained a hybrid system loaded with holmium and anticancer drugs and thoroughly studied it with respect to the size, morphology, surface modifications and magnetic properties, and interactions with the model of biological membranes, cytotoxicity. We present that nanoparticles having a round shape and size 15 nm are successfully stabilized to avoid their agglomeration and modified with doxorubicin or epirubicin within a controlled way. The number of drugs loaded into the SPIONs was confirmed with thermogravimetry. The hybrid based on SPIONs was investigated in touch with model biological membranes within the Langmuir-Blodgett technique, and results show that modified SPION interacts effectively with them. Results obtained with magnetic hyperthermia and biological studies confirm the promising properties of the hybrid towards future cancer cell treatment.

Triumph against cancer: invading colorectal cancer with nanotechnology

INTRODUCTION

Recent statistics have reported colorectal cancer (CRC) as the second leading cause of cancer-associated deaths in the world. Early diagnosis of CRC may help to reduce the mortality and associated complications. However, the conventional diagnostic techniques often lead to misdiagnosis, fail to differentiate benign from malignant tissue or diagnose only at an advanced stage. For the treatment of CRC, surgery, chemotherapy, immunotherapy, and radiotherapy have been employed. However, the quality of living of the CRC patients is highly compromised after employing current therapeutic approaches owing to the toxicity issues and relapse.

AREA COVERED

This review accentuates the molecular mechanisms involved in the pathogenesis, stages of CRC, conventional approaches for diagnosis and therapy of CRC and the issues confronted thereby. It provides an outlook on the advantages of employing nanotechnology-based approaches for prevention, early diagnosis, and treatment of CRC.

EXPERT OPINION

Employing nanotechnology-based approaches has demonstrated promising outcomes in the prevention, diagnosis, and treatment of CRC. Nanotechnology-based approaches can surmount the major drawbacks of traditional diagnostic and therapeutic approaches. Nanotechnology bestows the advantage of early detection of CRC which helps to undertake instant steps for offering efficient therapy and reducing the mortality rates. For the treatment of CRC, nanocarriers offer the benefit of achieving controlled drug release, improved drug bioavailability, enhanced tumor targetability and reduced adverse effects.

Nonspecific nuclear uptake of anti-MUC1 aptamers by dead cells: the role of cell viability monitoring in aptamer targeting of membrane-bound protein cancer biomarkers

Most aptamers targeting cell-expressed antigens are intended for in vivo application, however, these sequences are commonly generated in vitro against synthetic oligopeptide epitopes or recombinant proteins. As these in vitro analogues frequently do not mimic the in vivo target within an endogenous environment, the evolved aptamers are often prone to nonspecific binding. The presence of dead cells and cellular debris further complicate aptamer targeting, due to their high nonspecific affinities to single-stranded DNA. Despite these known limitations, assessment of cell viability and/or the removal of dead cells is rarely applied as part of the methodology during in vivo testing of aptamer binding. Furthermore, the extent and route(s) by which dead cells uptake existing aptamers remains to be determined in the literature. For this purpose, the previously reported aptamer sequences 5TR1, 5TR4, 5TRG2 and S22 - enriched against the MUC1 tumour marker of the mucin glycoprotein family - were used as model sequences to evaluate the influence of cell viability and the presence of nontarget cell-expressed protein on aptamer binding to the MUC1 expressing human cancer cell lines MCF-7, Hs578T, SW480, and SW620. From fluorescence microscopy analysis, all tested aptamers demonstrated extensive nonspecific uptake within the nuclei of dead cells with compromised membrane integrities. Using fluorescent-activated cell sorting (FACS), the inclusion of excess double-stranded DNA as a blocking agent showed no effect on nonspecific aptamer uptake by dead cells. Further nonspecific binding to cell-membrane bound and intracellular protein was evident for each aptamer sequence, as assessed by southwestern blotting and FACS. These factors likely contributed to the ∼120-fold greater binding response of the 5TR1 aptamer to dead MCF-7 cells over equivalent live cell populations. The identification of dead cells and cellular debris using viability stains and the subsequent exclusion of these cells from FACS analysis was identified as an essential requirement for the evaluation of aptamer binding specificity to live cell populations of the cancer cell lines MCF-7, Hs578T and SW480. The research findings stress the importance of dead cell uptake and more comprehensive cell viability screening to validate novel aptamer sequences for diagnostic and therapeutic application.

Fabrication and evaluation of aptamer-conjugated paclitaxel-loaded magnetic nanoparticles for targeted therapy on breast cancer cells

Targeted drug delivery vehicles make it possible to deliver anti-cancer drugs to the cells or tissues of interest. Aptamers are peptide or oligonucleotide molecules that can serve as targeting elements of drug carriers. In the current study, we evaluated the capacity of an aptamer-based drug carrier to deliver Paclitaxel (PTX) to cancer cells. After being synthesized, SPIONs@PTX-SYL3C aptamer was characterized using different methods, including differential light scattering (DLS), infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Encapsulation efficiency (EE) and loading efficiency (LE) were also evaluated. The carrier was applied on 4T1, MCF 7, and MCF-10A breast cell lines to evaluate its drug delivery potency and specificity. EE and LE were calculated to be 77.6% and 7.76%, respectively. MTT results revealed that aptameric SPIONs@PTX was more toxic than non-aptameric SPIONs@PTX. Flowcytometry analysis and DAPI staining confirmed that SPIONs@PTX-Aptamer had higher cell internalization rate when compared to non-targeted SPIONs@PTX. Our results indicate that aptamer-conjugated SPIONs@PTX has a good capacity in recognizing its target cells and inhibiting their growth and division.

Progress of Cancer Nanotechnology as Diagnostics, Therapeutics, and Theranostics Nanomedicine: Preclinical Promise and Translational Challenges

Early detection, right therapeutic intervention, and simultaneous effectiveness mapping are considered the critical factors in successful cancer therapy. Nevertheless, these factors experience the limitations of conventional cancer diagnostics and therapeutics delivery approaches. Along with providing the targeted therapeutics delivery, advances in nanomedicines have allowed the combination of therapy and diagnostics in a single system (called cancer theranostics). This paper discusses the progress in the pre-clinical and clinical development of therapeutics, diagnostics, and theranostics cancer nanomedicines. It has been well evident that compared to the overabundance of works that claimed success in pre-clinical studies, merely 15 and around 75 cancer nanomedicines are approved, and currently under clinical trials, respectively. Thus, we also brief the critical bottlenecks in the successful clinical translation of cancer nanomedicines.

Aptamer-Functionalized Nanoparticles in Targeted Delivery and Cancer Therapy

Using nanoparticles to carry and delivery anticancer drugs holds much promise in cancer therapy, but nanoparticles per se are lacking specificity. Active targeting, that is, using specific ligands to functionalize nanoparticles, is attracting much attention in recent years. Aptamers, with their several favorable features like high specificity and affinity, small size, very low immunogenicity, relatively low cost for production, and easiness to store, are one of the best candidates for the specific ligands of nanoparticle functionalization. This review discusses the benefits and challenges of using aptamers to functionalize nanoparticles for active targeting and especially presents nearly all of the published works that address the topic of using aptamers to functionalize nanoparticles for targeted drug delivery and cancer therapy.

Molecular Magnetic Resonance Imaging with Contrast Agents for Assessment of Inflammatory Bowel Disease: A Systematic Review

Background and Aims

Magnetic resonance imaging (MRI) has taken an important role in the diagnosis of inflammatory bowel diseases (IBD). In the wake of current advances in nanotechnology, the drug delivery industry has seen a surge of nanoparticles advertising high specificity in target imaging. Given the rapid development of the field, this review has assembled related articles to explore whether molecular contrast agents can improve the diagnostic capability on gastrointestinal imaging, especially for IBD.

Methods

Relevant articles published between 1998 and 2018 from a literature search of PubMed and EMBASE were reviewed. Data extraction was performed on the studies' characteristics, experimental animals, modelling methods, nanoparticles type, magnetic resonance methods, and means of quantitative analysis.

Results

A total of 8 studies were identified wherein the subjects were animals, and all studies employed MR equipment. One group utilized a perfluorocarbon solution and the other 7 groups used either magnetic nanoparticles or gadolinium- (Gd-) related nanoparticles for molecular contrast. With ultrasmall superparamagnetic iron oxide (USPIO) particles and Gd-related nanoparticles, signal enhancements were found in the mucosa or with focal lesion of IBD-related model in T1-weighted images (T1WI), whereas superparamagnetic iron oxide (SPIO) particles showed a signal decrease in the intestinal wall of the model in T1WI or T2-weighted images. The signal-to-noise ratio (SNR) was employed to analyze bowel intensity in 3 studies. And the percentage of normalized enhancement was used in 1 study for assessing the severity of inflammation.

Conclusion

Molecular MRI with contrast agents can improve the early diagnosis of IBD and quantitate the severity of inflammation in experimental studies.

Strategies to bioengineer aptamer-driven nanovehicles as exceptional molecular tools for targeted therapeutics: A review

Aptamers are a class of folded nucleic acid strands capable of binding to different target molecules with high affinity and selectivity. Over the years, they have gained a substantial amount of interest as promising molecular tools for numerous medical applications, particularly in targeted therapeutics. However, only the different treatment approaches and current developments of aptamer-drug therapies have been discussed so far, ignoring the crucial technical and functional aspects of constructing a therapeutically effective aptamer-driven drug delivery system that translates to improved in-vivo performance. Hence, this paper provides a comprehensive review of the strategies used to improve the therapeutic performance of aptamer-guided delivery systems. We focus on the different functional features such as drug deployment, payload capacity, in-vivo stability and targeting efficiency to further our knowledge in enhancing the cell-specific delivery of aptamer-drug conjugates. Each reported strategy is critically discussed to emphasize both the benefits provided in comparison with other similar techniques and to outline their potential drawbacks with respect to the molecular properties of the aptamers, the drug and the system to be designed. The molecular architecture and design considerations for an efficient aptamer-based delivery system are also briefly elaborated.

Targeting strategies for superparamagnetic iron oxide nanoparticles in cancer therapy

Among various nanoparticles, superparamagnetic iron oxide nanoparticles (SPIONs) have been increasingly studied for their excellent superparamagnetism, magnetic heating properties, and enhanced magnetic resonance imaging (MRI). The conjugation of SPIONs with drugs to obtain delivery nanosystems has several advantages including magnetic targeted functionalization, in vivo imaging, magnetic thermotherapy, and combined delivery of anticancer agents. To further increase the targeting efficiency of drugs through a delivery nanosystem based on SPIONs, additional targeting moieties including transferrin, antibodies, aptamers, hyaluronic acid, folate, and targeting peptides are coated onto the surface of SPIONs. Therefore, this review summarizes the latest progresses in the conjugation of targeting molecules and drug delivery nanosystems based on SPIONs, especially focusing on their performances to develop efficient targeted drug delivery systems for tumor therapy. STATEMENT OF SIGNIFICANCE: Some magnetic nanoparticle-based nanocarriers loaded with drugs were evaluated in patients and did not produce convincing results, leading to termination of clinical development in phase II/III. An alternative strategy for drug delivery systems based on SPIONs is the conjugation of these systems with targeting segments such as transferrin, antibodies, aptamers, hyaluronic acid, folate, and targeting peptides. These targeting moieties can be recognized by specific integrin/receptors that are overexpressed specifically on the tumor cell surface, resulting in minimizing dosage and reducing off-target effects. This review focuses on magnetic nanoparticle-based nonviral drug delivery systems with targeting moieties to deliver anticancer drugs, with an aim to provide suggestions on the development of SPIONs through discussion.

Present Scenario of Bioconjugates in Cancer Therapy: A Review

Cancer is one of the deadliest diseases and poses a risk to people all over the world. Surgery, chemo, and radiation therapy have been the only options available until today to combat this major problem. Chemotherapeutic drugs have been used for treatment for more than 50 years. Unfortunately, these drugs have inherent cytotoxicities and tumor cells have started inducing resistance against these drugs. Other common techniques such as surgery and radiotherapy have their own drawbacks. Therefore, such techniques are incompetent tools to alleviate the disease efficiently without any adverse effects. This scenario has inspired researchers to develop alternative techniques with enhanced therapeutic effects and minimal side effects. Such techniques include targeted therapy, liposomal therapy, hormonal therapy, and immunotherapy, etc. However, these therapies are expensive and not effective enough. Furthermore, researchers have conjugated therapeutic agents or drugs with different molecules, delivery vectors, and/or imaging modalities to combat such problems and enhance the therapeutic effect. This conjugation technique has led to the development of bioconjugation therapy, in which at least one molecule is of biological origin. These bioconjugates are the new therapeutic strategies, having prospective synergistic antitumor effects and have potency to overcome the complications being produced by chemo drugs. Herein, we provide an overview of various bioconjugates developed so far, as well as their classification, characteristics, and targeting approach for cancer. Additionally, the most popular nanostructures based on their organic or inorganic origin (metallic, magnetic, polymeric nanoparticles, dendrimers, and silica nanoparticles) characterized as nanocarriers are also discussed. Moreover, we hope that this review will provide inspiration for researchers to develop better bioconjugates as therapeutic agents.

Selective chemotherapy and imaging of colorectal and breast cancer cells by a modified MUC-1 aptamer conjugated to a poly(ethylene glycol)-dimethacrylate coated Fe3O4–AuNCs nanocomposite

The combination of diagnosis and targeted therapy within a single nanoplatform is one of the remarkable advances in molecular medicine.

Recent advances in magnetic fluid hyperthermia for cancer therapy

Recently, magnetic fluid hyperthermia using biocompatible magnetic nanoparticles as heat mediators for cancer therapy has been extensively investigated due to its high efficiency and limited side effects. However, the development of more efficient heat nanomediators that exhibit very high specific absorption rate (SAR) value is essential for clinical application to overcome the several restrictions previously encountered due to the large quantity of nanomaterial required for effective treatment. In this review, we focus on the current progress in the development of magnetic nanoparticles based hyperthermia therapy as well as combined therapy harnessing hyperthermia with heat-mediated drug delivery for cancer treatment. We also address the fundamental principles of magnetic hyperthermia, basics of magnetism including the effect of several parameters on heating capacity, synthetic methods and nanoparticle surface chemistry needed to design and develop an ideal magnetic nanoparticle heat mediator suitable for clinical translation in cancer therapy.

Nucleic acid aptamers in diagnosis of colorectal cancer

Nucleic acid aptamers are promising recognition ligands for diagnostic applications. They are short DNA or RNA molecules isolated from large random libraries through the Systematic Evolution of Ligands by EXponential enrichment (SELEX) procedure. These molecules, with a particular three-dimensional shape, bind to a wide range of targets from small molecules to whole cells with high affinity and specificity. The unique properties of nucleic acid aptamers including high binding affinity and specificity, thermostability, ease of chemical production, ease of chemical modification, target adaptability, simple storage, resistance to denaturation, low immunogenicity, and low cost make them potential diagnostic tools for clinical use. Colorectal cancer is one of the most common types of cancer in humans and the third leading cause of cancer deaths in the world. Due to low response rate to current therapies in advanced stages of the disease, early detection of CRC can be useful in disease management. This review highlights recent advances in the development of nucleic acid aptamer-based methods for diagnosis, prognosis, and theranosis of colorectal cancer.

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.

Gold Coated Superparamagnetic Iron Oxide Nanoparticles as Effective Nanoparticles to Eradicate Breast Cancer Cells via Photothermal Therapy

Purpose: Unique physiochemical properties of Fe₂O₃ nanoparticles make them great agents to serve as therapeutic and diagnostic nanoparticles (NPs). In this study, we developed gold coated Fe₂O₃ nanoparticles for photothermal therapy of breast cancer cells.

Methods: Fe₂O₃ nanoparticles was prepared via microemulsion method and their surface was modified via gold. Differential light scattering (DLS) and transmission electron microscopy (TEM) methods were applied to evaluate physicochemical properties of NPs. Gold coated NP was further modified with MUC-1 aptamer as a targeting agent to increase drug delivery into the desired tissue. To evaluate cytotoxicity of prepared cells, MTT assay was employed. Targeting ability of aptamer modified NPs was assessed through confocal microscopy and flow cytometry method. Subsequently, MCF-7 and CHO cells were treated with aptamer modified NPs and were then irradiated via near infrared light (NIR) to produce heat.

Results: The morphology of NPs was spherical and monodisperse with the size of 16 nm, which was confirmed via DLS and TEM. Confocal microscopy and flow cytometry results indicated that aptamer modified NPs had higher uptake compared to bare NPs. Finally, NIR exposure results revealed that higher uptake of NPs and application of NIR led to significant death of MCF-7 cells compared to CHO cells.

Conclusion: To sum up, aptamer modified Fe₂O₃ nanoparticles showed higher uptake by cancerous cells and led to eradication of cancerous cells after exposure to NIR light.

Targeted co-delivery of epirubicin and NAS-24 aptamer to cancer cells using selenium nanoparticles for enhancing tumor response in vitro and in vivo

Chemotherapy is a commonly used cancer treatment strategy that causes severe side effects by damaging normal tissue. Therefore, targeted drug delivery systems have attracted great attention for the treatment of cancer in recent years. In this study, epirubicin (EPI)-loaded-NAS-24-functionalized PEI-PEG-5TR1 aptamer coated selenium nanoparticles (SeNPs), known as the ENPPASe complex, were developed and used for targeted delivery of both EPI (anticancer drug) and NAS-24 aptamer (apoptosis induction agent) to MCF7 (human breast carcinoma cell) and C26 (murine colon carcinoma cell) cancer cells using 5TR1 aptamer as the target agent. The ENPPASe complex could significantly reduce the toxicity in non-target cells (HEPG2, hepatocellular carcinoma cell). As with the EPI alone, the ENPPASe complex could significantly reduce cell viability in the target cancer cells (MCF-7 and C26). In addition, the complex significantly reduced the tumor growth in cancer-bearing mice compared to EPI treatment alone.

Curcumin-lipoic acid conjugate as a promising anticancer agent on the surface of gold‑iron oxide nanocomposites: A pH-sensitive targeted drug delivery system for brain cancer theranostics

Brain tumor is a lethal, fast growing cancer and a difficult case for treatment. Receptor-mediated endocytosis has been recognized as one of the most effective methods for drug delivery to brain tissue by overcoming obstacles associated with conventional therapeutics. In this work, a targeted theranostic drug delivery system (DDS) was prepared based on gold‑iron oxide nanocomposites (Fe₃O₄@Au NCs). Lipoic acid-curcumin (LA-CUR) was synthesized and introduced as a novel anticancer drug, and glutathione (GSH) was exploited as the targeting ligand. Both LA-CUR and GSH were easily attached to Fe₃O₄@Au NCs via Au-S interaction. As a negatively charged nanocarrier, the prepared DDS showed relatively less protein adsorption. Accordingly, hemocompatibility assays (complement, platelet, and leucocyte activation) revealed its hemocompatible virtue, especially in respect of free LA-CUR. GSH functionalization led to 2-fold increase of cellular uptake in GSH receptor-positive astrocyte cells which could primarily indicate the probable ability of the DDS to bypass BBB. Cytotoxicity and apoptosis assays together showed the noticeably enhanced cytotoxicity of LA-CUR against cancerous U87MG cells (IC50=2.69μg/ml) in comparison with curcumin (IC50=21.31μg/ml); moreover, the DDS demonstrated relatively higher cytotoxicity against cancerous U87MG cells than normal astrocyte cells which was in accordance with pH sensitive mechanism of LA-CUR release. Besides, the results of in vitro magnetic resonance imaging (MRI) (relaxation rate (r₂)=80.73 (s^-1·mM^-1)) primarily revealed that the DDS can be applied as a negative MRI contrast agent. In sum, the prepared DDS appeared to be a promising candidate for brain cancer treatment and a favorable MRI contrast agent.

5TR1 aptamer-PEGylated liposomal doxorubicin enhances cellular uptake and suppresses tumour growth by targeting MUC1 on the surface of cancer cells

Employing targeting ligands with high affinity to tumour receptors is an important strategy to increase treatment efficacy. The use of aptamers as targeting agent is increasingly prevalent in drug delivery systems. Mucin1 (MUC1) is a glycoprotein that is over-expressed on the surface of several cancer cells and plays an important role in metastasis and invasion. 5TR1-aptamer is a DNA aptamer, which targets MUC1 receptors. The present study investigated the anti-tumour activity and therapeutic effectiveness of 5TR1-aptamer-PEGylated liposomal doxorubicin (PLD) delivery system in C26 tumour-bearing mice. The in vitro experiments demonstrated enhanced cytotoxicity and cellular uptake of PLD at the presence of 5TR1 aptamer into MUC1⁺C26 cell line. Biodistribution study indicated that aptamer conjugation increased tumour accumulation of PLDs. Pharmacokinetic analysis showed despite higher clearance rate, selective delivery of doxorubicin to tumour tissue was increased in the 5TR1-Doxil group. In C26-bearing tumour mice, treatment with 5TR1-Doxil exhibited significant deceleration in tumour growth and enhanced survival. The results suggested that 5TR1 aptamer is promising ligand for active targeting which improves therapeutic efficiency of PLD in cancer therapy.

Nucleic acid aptamer application in diagnosis and therapy of colorectal cancer based on cell-SELEX technology

Nucleic acid aptamers are a class of high-affinity nucleic acid ligands. They serve as “chemical antibodies” since their high affinity and specificity. Nucleic acid aptamers are generated from nucleic acid random-sequence using a systematic evolution of ligands by exponential enrichment (SELEX) technology. SELEX is a process of effectively selecting aptamers from different targets. A newly developed cell-based SELEX technique has been widely used in biomarker discovery, early diagnosis and targeted cancer therapy, particular at colorectal cancer (CRC). Combined with nanostructures, nano-aptamer-drug delivery system was constructed for drug delivery. Various nanostructures functionalized with aptamers are highly efficient and has been used in CRC therapeutic applications. In the present, we introduce a cell- SELEX technique, and summarize the potential application of aptamers as biomarkers in CRC diagnosis and therapy. And some characteristics of aptamer-targeted nanocarriers in CRC have been expatiated. The challenges and perspectives for cell-SELEX are also discussed.

MUC1 aptamer-conjugated mesoporous silica nanoparticles effectively target breast cancer cells

In the present study, we developed aptamer (Apt) conjugated mesoporous silica nanoparticles (MSNs) for specific delivery of epirubicin (EPI) to breast cancer cells. MSNs were synthesized and functionalized with 3-mercaptopropyltrimethoxysilane (3-MPTMS), followed by MUC1 aptamer conjugation through disulfide bonds. The nanoparticles were analyzed by transmission electron microscopy (TEM), particle size analyzer, zeta potential, elemental analysis (CHNS), aptamer conjugation efficiency, drug loading efficiency, and drug release profile. Cell uptake and in vitro cytotoxicity of different formulations were performed. The results of MSNs characterization confirmed spherical nanoparticles with thiol functional groups. Particle size of obtained nanoparticles was 163 nm in deionized water. After conjugation of MUC1 aptamer and EPI loading (MSN-MUC1-EPI), particle size increased to 258 nm. The aptamer conjugation to MSNs with disulfide bonds were confirmed using gel retardation assay. Cellular uptake studies revealed better cell uptake of MSN-MUC1-EPI compared to MSN-EPI. Moreover, cytotoxicity study results in MCF7 cell lines showed improved cytotoxicity of MSN-MUC1-EPI in comparison with MSN-EPI or EPI at the same concentration of drug. These results exhibited that MSN-MUC1-EPI has the potential for targeted drug delivery into MUC1 positive breast cancer cells to improve drug efficacy and alleviate side effects.

Anti-MUC1 aptamer: A potential opportunity for cancer treatment

Mucin 1 (MUC1) is a protein usually found on the apical surface of most normal secretory epithelial cells. However, in most adenocarcinomas, MUC1 is overexpressed, so that it not only appears over the entire cell surface, but is also shed as MUC1 fragments into the blood stream. These phenomena pinpoint MUC1 as a potential target for the diagnosis and treatment of cancer; consequently, interest has increased in MUC1 as a molecular target for overcoming cancer therapy challenges. MUC1 currently ranks second among 75 antigen candidates for cancer vaccines, and different antibodies or aptamers against MUC1 protein are proving useful for tracing cancer cells in the emerging field of targeted delivery. The unique properties of MUC1 aptamers as novel targeting agents, and the revolutionary role that MUC1 now plays in cancer therapy, are the focus of this review. Recent advancements in MUC1-targeted cancer therapy are also assessed.

Aptasensors for quantitative detection of Salmonella Typhimurium

Salmonella is one of the most frequent causes of food borne infectious disease. Among nearly 2500 documented serotypes are reported, Salmonella Typhimurium is the number one serotype associated with salmonellosis worldwide. Many different methods have been developed for the detection and quantification of S. typhimurium. Most of these assays are usually expensive, time consuming and require difficult sample preparation steps. Therefore, it is necessary to develop rapid, robust, cost-effective and sensitive alternative detection methods. In the last years, aptasensors, used for detection of S. typhimurium in different samples. In this review, recent advances and applications of aptasensors for the detection and quantification of S. typhimurium in details have been summarized.

Targeted Magnetic Nanotheranostics of Cancer

Current advances in targeted magnetic nanotheranostics are summarized in this review. Unique structural, optical, electronic and thermal properties of magnetic materials in nanometer scale are attractive in the field of biomedicine. Magnetic nanoparticles functionalized with therapeutic molecules, ligands for targeted delivery, fluorescent and other chemical agents can be used for cancer diagnostic and therapeutic purposes. High selectivity, small size, and low immunogenicity of synthetic nucleic acid aptamers make them attractive delivery agents for therapeutic purposes. Properties, production and functionalization of magnetic nanoparticles and aptamers as ligands for targeted delivery are discussed herein. In recent years, magnetic nanoparticles have been widely used in diagnostic methods, such as scintigraphy, single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), and Raman spectroscopy. Therapeutic purposes of magnetic nanoconstructions are also promising. They are used for effective drug delivery, magnetic mediated hypertermia, and megnetodynamic triggering of apoptosis. Thus, magnetic nanotheranostics opens a new venue for complex differential diagnostics, and therapy of metastatic cancer.

Strategies for targeted drug delivery in treatment of colon cancer: current trends and future perspectives

Despite advances in treatment modalities, colon cancer (CC) is the third most common cause of cancer-related death worldwide. Subsequent unfavorable effects owing to toxicity of conventional drugs are a challenging problem associated with chemotherapy. There is noticeable concern toward site-specific/targeted delivery of chemotherapeutic drugs specifically to the affected site of the colon in a predictable and reproducible manner. However, the biggest challenge in successful drug targeting for the colon is avoidance of drug absorption and/or degradation in the upper gastrointestinal tract before the drug reaches the colon. Nanoparticles endowed with targeting abilities offer a novel approach for site-specific delivery of chemotherapeutic agents. The present review focuses on recent approaches for colon-specific drug delivery (CDDS) and aims to unveil the emerging possibilities and advances in the treatment of CC with CDDS.

Photo-controlled aptamers delivery by dual surface gold-magnetic nanoparticles for targeted cancer therapy

Dual surfaced dumbbell-like gold magnetic nanoparticles (Au-Fe₃O₄) were synthesized for targeted aptamers delivery. Their unique biological properties were characterized as a smart photo-controlled drug carrier. DNA aptamers targeting vascular endothelial growth factor (VEGF) were assembled onto the surface of Au-Fe₃O₄ by electrostatic absorption. The binding capacity of the nanoparticles with VEGF aptamers was confirmed by gel electrophoresis. The targeted recognization of ovarian cancer cells by the aptamers-functionalized Au-Fe₃O₄ nanoparticles (Apt-Au-Fe₃O₄ NPs) was observed by confocal microscopy. Apt-Au-Fe₃O₄ was found to bind with SKOV-3 ovarian cancer cells specifically, leading to marked intracellular release of aptamers upon plasmon-resonant light (605nm) radiation, and to enhance the in vitro inhibition against tumor cell proliferation. The results show high potential of Apt-Au-Fe₃O₄as a targeted cancer hyperthermia carrier by remote control with high spatial/temporal resolution.

In vitro and in vivo evaluation of anti-nucleolin-targeted magnetic PLGA nanoparticles loaded with doxorubicin as a theranostic agent for enhanced targeted cancer imaging and therapy

A superparamagnetic iron oxide nanoparticles (SPIONs)/doxorubicin (Dox) co-loaded poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles targeted with AS1411 aptamer (Apt) against murine C26 colon carcinoma cells is successfully developed via a modified multiple emulsion solvent evaporation method for theranostic purposes. The mean size of SPIO/Dox-NPs (NPs) was 130nm with a narrow particle size distribution and Dox loading of 3.0%. The SPIO loading of 16.0% and acceptable magnetic properties are obtained and analyzed using thermogravimetric and vibration simple magnetometer analysis, respectively. The best release profile from NPs was observed in PBS at pH 7.4, in which very low burst release was observed. Nucleolin is a targeting ligand to facilitate anti-tumor delivery of AS1411-targeted NPs. The Apt conjugation to NPs (Apt-NPs) enhanced cellular uptake of Dox in C26 cancer cells. Apt-NPs enhance the cytotoxicity effect of Dox followed by a significantly higher tumor inhibition and prolonged animal survival in mice bearing C26 colon carcinoma xenografts. Furthermore, Apt-NPs enhance the contrast of magnetic resonance images in tumor site. Altogether, these Apt-NPs could be considered as a powerful tumor-targeted delivery system for their potential as dual therapeutic and diagnostic applications in cancers.

Application of aptamers in diagnostics, drug-delivery and imaging

Aptamers are small, single-stranded oligonucleotides (DNA or RNA) that bind to their target with high specificity and affinity. Although aptamers are analogous to antibodies for a wide range of target recognition and variety of applications, they have significant advantages over antibodies. Since aptamers have recently emerged as a class of biomolecules with an application in a wide array of fields, we need to summarize the latest developments herein. In this review we will discuss about the latest developments in using aptamers in diagnostics, drug delivery and imaging. We begin with diagnostics, discussing the application of aptamers for the detection of infective agents itself, antigens/ toxins (bacteria), biomarkers (cancer), or a combination. The ease of conjugation and labelling of aptamers makes them a potential tool for diagnostics. Also, due to the reduced off-target effects of aptamers, their use as a potential drug delivery tool is emerging rapidly. Hence, we discuss their use in targeted delivery in conjugation with siRNAs, nanoparticles, liposomes, drugs and antibodies. Finally, we discuss about the conjugation strategies applicable for RNA and DNA aptamers for imaging. Their stability and self-assembly after heating makes them superior over protein-based binding molecules in terms of labelling and conjugation strategies.