Engineering of targeted nanoparticles for cancer therapy using internalizing aptamers isolated by cell-uptake selection

Biomolecule-functionalized nanoformulations for prostate cancer theranostics

BACKGROUND

Even with the advancement in the areas of cancer nanotechnology, prostate cancer still poses a major threat to men's health. Nanomaterials and nanomaterial-derived theranostic systems have been explored for diagnosis, imaging, and therapy for different types of cancer still, for prostate cancer they have not delivered at full potential because of the limitations like in vivo biocompatibility, immune responses, precise targetability, and therapeutic outcome associated with the nanostructured system.

AIM OF REVIEW

Functionalizing nanomaterials with different biomolecules and bioactive agents provides advantages like specificity towards cancerous tumors, improved circulation time, and modulation of the immune response leading to early diagnosis and targeted delivery of cargo at the site of action.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we have emphasized the classification and comparison of various nanomaterials based on biofunctionalization strategy and source of biomolecules such that it can be used for possible translation in clinical settings and future developments. This review highlighted the opportunities for embedding highly specific biological targeting moieties (antibody, aptamer, oligonucleotides, biopolymer, peptides, etc.) on nanoparticles which can improve the detection of prostate cancer-associated biomarkers at a very low limit of detection, direct visualization of prostate tumors and lastly for its therapy. Lastly, special emphasis was given to biomimetic nanomaterials which include functionalization with extracellular vesicles, exosomes and viral particles and their application for prostate cancer early detection and drug delivery. The present review paves a new pathway for next-generation biofunctionalized nanomaterials for prostate cancer theranostic application and their possibility in clinical translation.

Stimuli-Responsive Multifunctional Nanomedicine for Enhanced Glioblastoma Chemotherapy Augments Multistage Blood-to-Brain Trafficking and Tumor Targeting

Minimal therapeutic advances have been achieved over the past two decades for glioblastoma (GBM), which remains an unmet clinical need. Here, hypothesis-driven stimuli-responsive nanoparticles (NPs) for docetaxel (DTX) delivery to GBM are reported, with multifunctional features that circumvent insufficient blood-brain barrier (BBB) trafficking and lack of GBM targeting-two major hurdles for anti-GBM therapies. NPs are dual-surface tailored with a i) brain-targeted acid-responsive Angiopep-2 moiety that triggers NP structural rearrangement within BBB endosomal vesicles, and ii) L-Histidine moiety that provides NP preferential accumulation into GBM cells post-BBB crossing. In tumor invasive margin patient cells, the stimuli-responsive multifunctional NPs target GBM cells, enhance cell uptake by 12-fold, and induce three times higher cytotoxicity in 2D and 3D cell models. Moreover, the in vitro BBB permeability is increased by threefold. A biodistribution in vivo trial confirms a threefold enhancement of NP accumulation into the brain. Last, the in vivo antitumor efficacy is validated in GBM orthotopic models following intratumoral and intravenous administration. Median survival and number of long-term survivors are increased by 50%. Altogether, a preclinical proof of concept supports these stimuli-responsive multifunctional NPs as an effective anti-GBM multistage chemotherapeutic strategy, with ability to respond to multiple fronts of the GBM microenvironment.

Controlled Release of DNA Binding Anticancer Drugs from Gold Nanoparticles with Near-Infrared Radiation

Traditional chemotherapies target rapidly developing cells in the human body resulting in harsh side effects including fatigue, immune system suppression, and nausea, among others. Delivery systems to focus the active pharmaceutical ingredients (APIs) to the diseased tissue can diminish the negative side effects while improving treatment outcomes. Gold nanoparticles (AuNP) offer many unique advantages as drug delivery vehicles, including being biologically inert, easily adaptable to various shapes and sizes, able to create a strong Au-thiol bond, and able to generate heat upon the absorption of near-infrared light. To this end, a AuNP delivery vehicle was engineered to load and release two DNA binding anti-cancer drugs, mithramycin and doxorubicin, in a controlled fashion. The drugs were loaded onto the surface of the AuNP with temperature sensitive linkages. The amount of heat generated, and subsequent release of the drugs was controlled by the irradiation time with a near-infrared laser. By modulating the linkage used to load the drugs three different release profiles were able to be achieved, indicating the feasibility of such a system for combinational therapy requiring sequential release of APIs.

Shall We Tune? From Core-Shell to Cloud Type Nanostructures in Heparin/Silica Hybrids

Heparin plays multiple biological roles depending on the availability of active sites strongly influenced by the conformation and the structure of polysaccharide chains. Combining different components at the molecular scale offers an extraordinary chance to easily tune the structural organization of heparin required for exploring new potential applications. In fact, the combination of different material types leads to challenges that cannot be achieved by each single component. In this study, hybrid heparin/silica nanoparticles were synthesized, and the role of silica as a templating agent for heparin supramolecular organization was investigated. The effect of synthesis parameters on particles compositions was deeply investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Transmission Electron Microscopy (TEM) reveals a different supramolecular organization of both components, leading to amazing organic-inorganic nanoparticles with different behavior in drug encapsulation and release. Furthermore, favorable biocompatibility for healthy human dermal fibroblasts (HDF) and tumor HS578T cells has been assessed, and a different biological behavior was observed, ascribed to different surface charge and morphology of synthesized nanoparticles.

Recent Advances in Aptamer-Based Liquid Biopsy

Liquid biopsy capable of noninvasive and real-time molecular profiling is considered as a breakthrough technology, endowing an opportunity for precise diagnosis of individual patients. Extracellular vesicles (EVs) and circulating tumor cells (CTCs) consisting of substantial disease-related molecular information play an important role in liquid biopsy. Therefore, it is critically significant to exploit high-performance recognition ligands for efficient isolation and analysis of EVs and CTCs from complex body fluids. Aptamers exhibit extraordinary merits of high specificity and affinity, which are considered as superior recognition ligands for liquid biopsy. In this review, we first summarize recent advanced strategies for the evolution of high-performance aptamers and the construction of various aptamer-based recognition elements. Subsequently, we mainly discuss the isolation and analysis of EVs and CTCs based on the aptamer functioned biomaterials/biointerface. Ultimately, we envision major challenges and future direction of aptamer-based liquid biopsy for clinical utilities.

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.

Biodegradable and Peroxidase-Mimetic Boron Oxynitride Nanozyme for Breast Cancer Therapy

Nanomaterials having enzyme-like activities are recognized as potentially important self-therapeutic nanomedicines. Herein, a peroxidase-like artificial enzyme is developed based on novel biodegradable boron oxynitride (BON) nanostructures for highly efficient and multi-mode breast cancer therapies. The BON nanozyme catalytically generates cytotoxic hydroxyl radicals, which induce apoptosis of 4T1 cancer cells and significantly reduce the cell viability by 82% in 48 h. In vivo experiment reveals a high potency of the BON nanozyme for breast tumor growth inhibitions by 97% after 14-day treatment compared with the control, which are 10 times or 1.3 times more effective than the inert or B-releasing boron nitride (BN) nanospheres, respectively. This work highlights the BON nanozyme and its functional integrations within the BN nanomedicine platform for high-potency breast cancer therapies.

Encapsulation of ribozymes inside model protocells leads to faster evolutionary adaptation

Functional biomolecules, such as RNA, encapsulated inside a protocellular membrane are believed to have comprised a very early, critical stage in the evolution of life, since membrane vesicles allow selective permeability and create a unit of selection enabling cooperative phenotypes. The biophysical environment inside a protocell would differ fundamentally from bulk solution due to the microscopic confinement. However, the effect of the encapsulated environment on ribozyme evolution has not been previously studied experimentally. Here, we examine the effect of encapsulation inside model protocells on the self-aminoacylation activity of tens of thousands of RNA sequences using a high-throughput sequencing assay. We find that encapsulation of these ribozymes generally increases their activity, giving encapsulated sequences an advantage over nonencapsulated sequences in an amphiphile-rich environment. In addition, highly active ribozymes benefit disproportionately more from encapsulation. The asymmetry in fitness gain broadens the distribution of fitness in the system. Consistent with Fisher's fundamental theorem of natural selection, encapsulation therefore leads to faster adaptation when the RNAs are encapsulated inside a protocell during in vitro selection. Thus, protocells would not only provide a compartmentalization function but also promote activity and evolutionary adaptation during the origin of life.

The use of aptamers in prostate cancer: A systematic review of theranostic applications

Since prostate cancer (PCa) relies on limited diagnosis and therapies, more effective alternatives are needed. Aptamers are versatile tools that may be applied for better clinical management of PCa patients. This review shows the trends on aptamer-based applications for PCa to understand their future development. We searched articles reporting aptamers applied in PCa on the Pubmed, Scopus and Web of Science databases over the last decade. Almost 80% of the articles used previously selected aptamers in novel approaches. However, cell-SELEX was the most applied technique for the selection of new aptamers allowing their binding to targets in their native configuration. ssDNA aptamers were 24% more common than RNA aptamers. The most studied PCa-specific aptamers were the DNA PSA-specific aptamer PSap4#5 and the PSMA-specific RNA aptamers A10 and A9, being PSA and PSMA the most reported targets. Thus, researchers still prefer the ease of use of DNA aptamers. Blood-based liquid biopsies represented 24% of all samples, being the most promising clinical samples. Especially noteworthy, electro-analytical methods accounted for more than 40% of the diagnostic techniques and treatment approaches with drug delivery systems or transcriptional modifiers were reported in 70% of the articles. Although all these articles showed clinically relevant aptamers for PCa and there are good prospects for their use, the development of all these strategies was in its early stages. Thus, the aptamers are not completely validated and we foresee that the completion of clinical studies will allow the implementation of these aptamer-based technologies in the clinical practice of PCa.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Aptamer-Based Detection of Circulating Targets for Precision Medicine

The past decade has witnessed ongoing progress in precision medicine to improve human health. As an emerging diagnostic technique, liquid biopsy can provide real-time, comprehensive, dynamic physiological and pathological information in a noninvasive manner, opening a new window for precision medicine. Liquid biopsy depends on the sensitive and reliable detection of circulating targets (e.g., cells, extracellular vesicles, proteins, microRNAs) from body fluids, the performance of which is largely governed by recognition ligands. Aptamers are single-stranded functional oligonucleotides, capable of folding into unique tertiary structures to bind to their targets with superior specificity and affinity. Their mature evolution procedure, facile modification, and affinity regulation, as well as versatile structural design and engineering, make aptamers ideal recognition ligands for liquid biopsy. In this review, we present a broad overview of aptamer-based liquid biopsy techniques for precision medicine. We begin with recent advances in aptamer selection, followed by a summary of state-of-the-art strategies for multivalent aptamer assembly and aptamer interface modification. We will further describe aptamer-based micro-/nanoisolation platforms, aptamer-enabled release methods, and aptamer-assisted signal amplification and detection strategies. Finally, we present our perspectives regarding the opportunities and challenges of aptamer-based liquid biopsy for precision medicine.

Hybrid Nanoparticles Modified by Hyaluronic Acid Loading an HSP90 Inhibitor as a Novel Delivery System for Subcutaneous and Orthotopic Colon Cancer Therapy

Background

As a therapeutic target for cancer treatment, HSP90 has been explored extensively. However, the significant side effects of the HSP90 inhibitor 17AAG have limited its clinical use.

Methods

In this study, we used hyaluronic acid (HA)–decorated DOTAP–PLGA hybrid nanoparticles (HA-DOTAP-PLGA NPs) as 17AAG-delivery carriers for targeted colon cancer therapy.

Results

Different methods were used to characterize the successful fabrication of these hybrid PLGA NPs. Our results demonstrated that internalization of HA-NPs in colon cancer cells was governed by CD44receptor–mediated endocytosis. Annexin V–propidium iodide staining experiments revealed that cell apoptosis induced by HA-NPs-17AAG in colon cancer cells was more efficient than free 17AAG. In two animal models used to screen anticancer efficacy (Luc-HT29 subcutaneous xenograft and AOM/DSS-induced orthotopic tumor model), HA-NPs-17AAG significantly inhibited xenograft and orthotopic tumor growth, demonstrating HA-NPs-17AAG had much better therapeutic efficiency than free 17AAG. It is worth noting that great biocompatibility of HA-DOTAP-PLGA NPs was observed both in vitro and in vivo.

Conclusion

Our research offers a preclinical proof of concept for colon cancer therapy with DOTAP-PLGA NPs as a creative drug-delivery system.

Nanosystem functionalization strategies for prostate cancer treatment: a review

Prostate cancer (PC) has a high morbidity and mortality rate worldwide, and the current clinical guidelines can vary depending on the stage of the disease. Drug delivery nanosystems (DDNs) can improve biopharmaceutical properties of encapsulated anti-cancer drugs by modulating their release kinetics, improving physicochemical stability and reducing toxicity. DDN can also enhance the ability of specific targeting through surface modification by coupling ligands (antibodies, nucleic acids, peptides, aptamer, proteins), thus favouring the cell internalisation process by endocytosis. The purposes of this review are to describe the limitations in the treatment of PC, explore different functionalization such as polymeric, lipid and inorganic nanosystems aimed at the treatment of PC, and demonstrate the improvement of this modification for an active target, as alternative and promising candidates for new therapies.

Multi-functional DNA-conjugated nanohydrogels for aptamer-directed breast cancer cell targeting

A multi-functional DNA-conjugated nanohydrogel was prepared through the direct copolymerization method for aptamer-directed cancer cell targeting.

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.

Application and development of aptamer in cancer: from clinical diagnosis to cancer therapy

Traditional anticancer therapies can cause serious side effects in clinical treatment due to their nonspecific of tumor cells. Aptamers, also termed as 'chemical antibodies', are short DNA or RNA oligonucleotides selected from the synthetic large random single-strand oligonucleotide library by systematic evolution of ligands by exponential enrichment (SELEX) to bind to lots of different targets, such as proteins or nucleic acid structures. Aptamers have good affinities and high specificity with target molecules, thus may be able to act as drugs themselves to directly inhibit the proliferation of tumor cells, or own great potentialities in the targeted drug delivery systems which can be used in tumor diagnosis and target specific tumor cells, thereby minimizing the toxicity to normal cells. Here we review the unique properties of aptamer represents a great opportunity when applied to the rapidly developing fields of biotechnology and discuss the recent developments in the use of aptamers as powerful tools for analytic, diagnostic and therapeutic applications for cancer.

Antibody-Enabled Antimicrobial Nanocapsules for Selective Elimination of Staphylococcus aureus

Targeted bactericide nanosystems hold significant promise to improve the efficacy of existing antimicrobials for treatment of severe bacterial infections, minimizing the side effects and lowering the risk of the development of antibiotic resistance. In this work, we developed antibody-functionalized nanocapsules (NCs) containing antibacterial essential oil (EO) for selective and effective eradication of Staphylococcus aureus. Antibacterial EO NCs were produced via self-assembly nanoencapsulation in the plant-derived protein zein. The obtained EO NCs were decorated with aminocellulose to provide more reactive surface groups for carboxyl-to-amine immobilization of a antibody that is specific against S. aureus. The antibody-enabled EO NCs (Ab@EO NCs) demonstrated 2-fold higher bactericidal efficacy against the targeted bacterium compared to the pristine EO NCs at the same concentrations. The improved antibacterial effect of the Ab@EO NCs toward S. aureus was also confirmed in a real-time assay by monitoring bacterial cells elimination using a quartz crystal microbalance. Furthermore, the Ab@EO NCs selectively decreased the load and changed the cell morphology of the targeted S. aureus in a mixed inoculum with nontargeted Pseudomonas aeruginosa. Applying the nanoformulated antibacterial actives to an in vitro coculture model of the bacteria and skin fibroblasts resulted in suppression of S. aureus growth while preserving the human cells viability. The novel antibody-enabled antibacterial NCs showed potential for improving the treatment efficacy of staphylococcal infections, minimally affecting the beneficial microbial and human cells.

Cancer-Targeting Nanoparticles for Combinatorial Nucleic Acid Delivery

Nucleic acids are a promising type of therapeutic for the treatment of a wide range of conditions, including cancer, but they also pose many delivery challenges. For efficient and safe delivery to cancer cells, nucleic acids must generally be packaged into a vehicle, such as a nanoparticle, that will allow them to be taken up by the target cells and then released in the appropriate cellular compartment to function. As with other types of therapeutics, delivery vehicles for nucleic acids must also be designed to avoid unwanted side effects; thus, the ability of such carriers to target their cargo to cancer cells is crucial. Classes of nucleic acids, hurdles that must be overcome for effective intracellular delivery, types of nonviral nanomaterials used as delivery vehicles, and the different strategies that can be employed to target nucleic acid delivery specifically to tumor cells are discussed. Additonally, nanoparticle designs that facilitate multiplexed delivery of combinations of nucleic acids are reviewed.

Nanoparticle-Mediated Dual Targeting: An Approach for Enhanced Baicalin Delivery to the Liver

In this study, water-soluble chitosan lactate (CL) was reacted with lactobionic acid (LA), a disaccharide with remarkable affinity to hepatic asialoglycoprotein (ASGP) receptors, to form dual liver-targeting LA-modified-CL polymer for site-specific drug delivery to the liver. The synthesized polymer was used to encapsulate baicalin (BA), a promising bioactive flavonoid with pH-dependent solubility, into ultrahigh drug-loaded nanoparticles (NPs) via the ionic gelation method. The successful chemical conjugation of LA with CL was tested and the formulated drug-loaded LA-modified-CL-NPs were assessed in terms of particle size (PS), encapsulation efficiency (EE) and zeta potential (ZP) using full factorial design. The in vivo biodistribution and pharmacokinetics of the designed NPs were assessed using ^99mTc-radiolabeled BA following oral administration to mice and results were compared to ^99mTc-BA-loaded-LA-free-NPs and ^99mTc-BA solution as controls. Results showed that the chemical modification of CL with LA was successfully achieved and the method of preparation of the optimized NPs was very efficient in encapsulating BA into nearly spherical particles with an extremely high EE exceeding 90%. The optimized BA-loaded-LA-modified-CL-NPs showed an average PS of 490 nm, EE of 93.7% and ZP of 48.1 mV. Oral administration of ^99mTc-BA-loaded-LA-modified-CL-NPs showed a remarkable increase in BA delivery to the liver over ^99mTc-BA-loaded-LA-free-CL-NPs and ^99mTc-BA oral solution. The mean area under the curve (AUC_0-24) estimates from liver data were determined to be 11-fold and 26-fold higher from ^99mTc-BA-loaded-LA-modified-CL-NPs relative to ^99mTc-BA-loaded-LA-free-CL-NPs and ^99mTc-BA solution respectively. In conclusion, the outcome of this study highlights the great potential of using LA-modified-CL-NPs for the ultrahigh encapsulation of therapeutic molecules with pH-dependent/poor water-solubility and for targeting the liver.

Aptamers Chemistry: Chemical Modifications and Conjugation Strategies

Soon after they were first described in 1990, aptamers were largely recognized as a new class of biological ligands that can rival antibodies in various analytical, diagnostic, and therapeutic applications. Aptamers are short single-stranded RNA or DNA oligonucleotides capable of folding into complex 3D structures, enabling them to bind to a large variety of targets ranging from small ions to an entire organism. Their high binding specificity and affinity make them comparable to antibodies, but they are superior regarding a longer shelf life, simple production and chemical modification, in addition to low toxicity and immunogenicity. In the past three decades, aptamers have been used in a plethora of therapeutics and drug delivery systems that involve innovative delivery mechanisms and carrying various types of drug cargos. However, the successful translation of aptamer research from bench to bedside has been challenged by several limitations that slow down the realization of promising aptamer applications as therapeutics at the clinical level. The main limitations include the susceptibility to degradation by nucleases, fast renal clearance, low thermal stability, and the limited functional group diversity. The solution to overcome such limitations lies in the chemistry of aptamers. The current review will focus on the recent arts of aptamer chemistry that have been evolved to refine the pharmacological properties of aptamers. Moreover, this review will analyze the advantages and disadvantages of such chemical modifications and how they impact the pharmacological properties of aptamers. Finally, this review will summarize the conjugation strategies of aptamers to nanocarriers for developing targeted drug delivery systems.

Nanostructured Systems in Advanced Drug Targeting for the Cancer Treatment: Recent Patents

BACKGROUND

Cancer is one of the leading causes of death in the world and it is necessary to develop new strategies for its treatment because most therapies have limited access to many types of tumors, as well as low therapeutic efficacy and high toxicity.

OBJECTIVE

The present research aims to identify recent patents of drug delivery nanostructured systems that may have application in improving cancer treatment.

METHODS

Recent patents regarding the drug delivery nanostructured systems for cancer treatment were obtained from the patent databases of the six main patent offices of the world: United States Patent and Trademark Office, European Patent Office, World Intellectual Property Organization, Japan Patent Office, State Intellectual Property Office of China and Korean Intellectual Property Office.

RESULTS

A total of 1710 patent documents from 1998 to 2017 including "drug delivery nanostructured systems for cancer treatment" were retrieved. The top five countries in patent share were USA, China, South Korea, Canada and Germany. The universities and enterprises of USA had the highest amount of patents followed by institutions from China.

CONCLUSION

There is a strong tendency for the development of new nanostructured systems for the release of drugs; particularly, in recent years, the development of nanoparticles has focused on nanodiscs, gold nanoparticles and immunoliposomes.

Preparation and purification of novel phosphatidyl prodrug and performance modulation of phosphatidyl nanoprodrug

Background

A novel phosphatidyl nanoprodrug system can be selectively released parent drugs in cancer cells, triggered by the local overexpression of phospholipase D (PLD). This system significantly reduces the intrinsic disadvantages of conventional chemotherapeutic drugs. However, the separation and purification processes of phosphatidyl prodrug, the precursor of phosphatidyl nanoprodrug, have not been established, and the preparation of nanocrystals with good stability and tumor-targeting capability is still challenging.

Results

In this study, we established a successive elution procedure for the phosphatidyl prodrug—phosphatidyl mitoxantrone (PMA), using an initial ten-bed volume of chloroform/methanol/glacial acetic acid/water (26/10/0.8/0.7) (v/v/v/v) followed by a five-bed volume (26/10/0.8/3), with which purity rates of 96.93% and overall yields of 50.35% of PMA were obtained. Moreover, to reduce the intrinsic disadvantages of conventional chemotherapeutic drugs, phosphatidyl nanoprodrug—PMA nanoprodrug (NP@PMA)—was prepared. To enhance their stability, nanoparticles were modified with polyethylene glycol (PEG). We found that nanoprodrugs modified by PEG (NP@PEG–PMA) were stably present in RPMI-1640 medium containing 10% FBS, compared with unmodified nanoprodrug (NP@PMA). To enhance active tumor-targeting efficiency, we modified nanoparticles with an arginine-glycine-aspartic acid (RGD) peptide (NP@RGD–PEG–PMA). In vitro cytotoxicity assays showed that, compared with the cytotoxicity of NP@PEG–PMA against tumor cells, that of NP@RGD–PEG–PMA was enhanced. Thus, RGD modification may serve to enhance the active tumor-targeting efficiency of a nanoprodrug, thereby increasing its cytotoxicity.

Conclusions

A process for the preparation and purification of novel phosphatidyl prodrugs was successfully established, and the nanoprodrug was modified using PEG for enhanced nanoparticle stability, and using RGD peptide for enhanced active tumor-targeting efficiency. These procedures offer considerable potential in the development of functional antitumor prodrugs.

Nanotechnology based therapeutic application in cancer diagnosis and therapy

Due to the lack of early diagnosis, cancer remains as one of the leading cause of human mortality. Inability to translate research into clinical trials and also inability of chemotherapeutics delivery to targeted tumor sites are major drawbacks in cancer therapeutics. With the emergence of nanomedicine, several nanoprobes (conjugated with targeting ligands and chemotherapeutic drugs) are developed. It can interact with biological system and thus sense and monitor the biological events with high efficiency and accuracy along with therapy application. Nanoparticles like gold and iron oxide are frequently used in the computed tomography and magnetic resonance imaging applications, respectively. Moreover, enzymatic activity of gold and iron oxide nanoparticles enables the visible colorimetric diagnostic of cancer cells, whereas, fluorescence property of quantum dots and upconversion nanoparticles helps in in vivo imaging application. Other than this, drug conjugation with nanoparticles also reduces the systemic toxic effect of chemotherapeutic drugs. Due to their several unique intrinsic properties, nanoparticles itself can also be employed as therapeutics in cancer treatment by photothermal therapy (PTT) and photodynamic therapy (PDT). Thus, the main focus of this review is to emphasize on current progress in diagnostic and therapeutic application of nanoprobes in cancer.

Selection of DNA-Encoded Libraries to Protein Targets within and on Living Cells

We report the selection of DNA-encoded small molecule libraries against protein targets within the cytosol and on the surface of live cells. The approach relies on generation of a covalent linkage of the DNA to protein targets by affinity labeling. This cross-linking event enables subsequent copurification by a tag on the recombinant protein. To access targets within cells, a cyclic cell-penetrating peptide is appended to DNA-encoded libraries for delivery across the cell membrane. As this approach assesses binding of DELs to targets in live cells, it provides a strategy for selection of DELs against challenging targets that cannot be expressed and purified as active.

Polydopamine-based surface modification of paclitaxel nanoparticles for osteosarcoma targeted therapy

In order to achieve the purpose of targeting treatment of osteosarcoma, we developed novel paclitaxel (PTX) nanoparticles (Nps) coated with polydopamine (PDA) and grafted by alendronate (ALN) as ligand. Dopamine can be easily polymerized on various surfaces to form a thin PDA film in alkaline environment, which provided a versatile platform to perform secondary reactions for compounds without functional groups. The targeting Nps had a mean particle size of 290.6 ± 2.2 nm and a zeta potential of -13.4 ± 2.7. It was stable in phosphate buffer saline (PBS, pH 7.4), 5% glucose, plasma and displayed sustained drug release behavior. In vitro assay demonstrated the targeting Nps had stronger cytotoxicity against K₇M₂ wt osteosarcoma cells than the non-targeting Nps. Furthermore, in vivo distribution study indicated they could accumulate much more in tumor than non-targeting Nps. This is consistent with the in vivo antitumor study, targeting Nps achieved a better therapeutic effect than Taxol (8 mg kg^-1, i.v.) (71.85% versus 66.53%) and prominently decreased the side effects of PTX. In general, the PTX-PDA-ALN-Nps may offer a feasible and effective strategy for osteosarcoma targeted therapy.

Polymer Nanoplatforms at Work in Prostate Cancer Therapy

Prostate cancer (PCa) is the most common male urogenital malignancy worldwide. Surgery, endocrine therapy, radiotherapy, and chemotherapy are the main clinical management options for PCa. However, these three therapies each have limitations. For example, surgery is not suitable for the advanced PCa patients with extensive metastases, and radiotherapy causes serious side effects. Primary endocrine therapy promotes the progression of hormone‐sensitive PCa into the castration‐resistant prostate cancer. Therefore, considering these drawbacks, chemotherapy has become an effective and extensive treatment for PCa. Among the modern therapeutic strategies against advanced PCa, polymer‐nanocarrier‐incorporated formulations have gradually emerged due to their well‐controlled release profiles and improved tumor targeting abilities. The drug delivery systems based on polymer nanoplatforms passively target tumors via the enhanced permeability and retention effect. Simultaneously, stimuli‐responsive polymer nanoplatforms unload cargoes in response to certain stimuli in the tumor area. Furthermore, the active targeting ligand‐conjugated polymer nanoformulations against PCa‐specific markers have also achieved great success in PCa therapies. Herein, the advanced polymer nanoplatforms for PCa therapy are reviewed, while the future development of polymer nanoplatforms for PCa therapy is also predicted.

Image-guided cancer therapy using aptamer-functionalized cross-linked magnetic-responsive Fe3O4@carbon nanoparticles

The excellent anticancer effect of combined differential cancer therapies has been observed in the last few decades. Efficient theragnostic nanoparticles (NPs) for malignancy treatment have received considerable research attention and widely investigated today. This study presents our results on the development of aptamer-functionalized Fe₃O₄@carbon@doxorubicin NPs (Apt-Fe₃O₄@C@DOX) and their application in the synergetic chemo-photothermal therapy (PTT) of cancer. The Apt-Fe₃O₄@C@DOX NPs displayed high photothermal conversion efficiency and extensive pH/heat-induced drug release. In vitro (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) bromide experiments indicated that the combined chemo-PTT is much more toxic toward lung adenocarcinoma cells (A549) than PTT or chemotherapy alone. In addition, the Apt-Fe₃O₄@C@DOX NPs demonstrated decreasing contrast enhancement of magnetic resonance (MR) signals, which means they may be potentially applied as a contrast agent and serve as a critical component of T₂-weighted MR imaging of tumor tissues. Taking the results together, the Apt-Fe₃O₄@C@DOX NPs show great potential for cancer therapy.

Cyclodextrin polymers decorated with RGD peptide as delivery systems for targeted anti-cancer chemotherapy

Polymeric cyclodextrin-based nanoparticles are currently undergoing clinical trials as nanotherapeutics. Using a non-covalent approach, we decorated two cross-linked cyclodextrin polymers of different molecular weights with an RGD peptide derivative to construct a novel carrier for the targeted delivery of doxorubicin. RGD is the binding sequence for the integrin receptor family that is highly expressed in tumour tissues. The assembled host-guest systems were investigated using NMR and DLS techniques. We found that, in comparison with free doxorubicin or the binary complex doxorubicin/cyclodextrin polymer, the RGD units decorating the cyclodextrin-based nanosystems improved the selectivity and cytotoxicity of the complexed doxorubicin towards cultured human tumour cell lines. Our results suggest that the nanocarriers under study may contribute to the development of new platforms for cancer therapy.

Calcium phosphate-based nanosystems for advanced targeted nanomedicine

Synthetic calcium phosphates (CaPs) are the most widely accepted bioceramics for the repair and reconstruction of bone tissue defects. The recent advancements in materials science have prompted a rapid progress in the preparation of CaPs with nanometric dimensions, tailored surface characteristics, and colloidal stability opening new perspectives in their use for applications not strictly related to bone. In particular, the employment of CaPs nanoparticles as carriers of therapeutic and imaging agents has recently raised great interest in nanomedicine. CaPs nanoparticles, as well as other kinds of nanoparticles, can be engineered to specifically target the site of the disease (cells or organs), thus minimizing their dispersion in the body and undesired organism-nanoparticles interactions. The most promising and efficient approach to improve their specificity is the 'active targeting', where nanoparticles are conjugated with a targeting moiety able to recognize and bind with high efficacy and selectivity to receptors that are highly expressed only in the therapeutic site. The aim of this review is to give an overview on advanced targeted nanomedicine with a focus on the most recent reports on CaP nanoparticles-based systems, specifically designed for the active targeting. The distinctive characteristics of CaP nanoparticles with respect to the other kinds of nanomaterials used in nanomedicine are also discussed.

Combination drug delivery via multilamellar vesicles enables targeting of tumor cells and tumor vasculature

Blood vessel development is critical for the continued growth and progression of solid tumors and, therefore, makes an attractive target for improving cancer therapy. Indeed, vascular-targeted therapies have been extensively explored but they have shown minimal efficacy as monotherapies. Combretastatin A4 (CA-4) is a tubulin-binding vascular disrupting agent that selectively targets the established tumor endothelium, causing rapid vascular beak down. Despite its potent anticancer potential, the drug has dose-limiting side effects, particularly in the form of cardiovascular toxicity. Furthermore, its poor aqueous solubility and the resulting limited bioavailability hinder its antitumor activity in the clinic. To improve the therapeutic efficacy of CA-4, we investigated its application as a combination therapy with doxorubicin (Dox) in a tumor vasculature targeted delivery vehicle: peptide-modified cross-linked multilamellar liposomal vesicles (cMLVs). In vitro cell culture studies showed that a tumor vasculature-targeting peptide, RIF7, could facilitate higher cellular uptake of drug-loaded cMLVs, and consequently enhance the antitumor efficacy in both drug resistant B16 mouse melanoma and human MDA-MB-231 breast cancer cells. In vivo, upon intravenous injection, targeted cMLVs could efficiently deliver both Dox and CA-4 to significantly slow tumor growth through the specific interaction of the targeting peptide with its receptor on the surface of tumor vasculature. This study demonstrates the potential of our novel targeted combination therapy delivery vehicle to improve the outcome of cancer treatment.

Nanomedicine: An effective tool in cancer therapy

Various types of nanoparticles (NPs) have been used in delivering anticancer drugs to the site of action. This area has become more attractive in recent years due to optimal size and negligible undesirable side effects caused by the NPs. The focus of this review is to explore various types of NPs and their surface/chemical modifications as well as attachment of targeting ligands for tuning their properties in order to facilitate targeted delivery to the cancer sites in a rate-controlled manner. Heme compatibility, biodistribution, longer circulation time, hydrophilic lipophilic balance for high bioavailability, prevention of drug degradation and leakage are important in transporting drugs to the targeted cancer sites. The review discusses advantages of polymeric, magnetic, gold, and mesoporous silica NPs in delivering chemotherapeutic agents over the conventional dosage formulations along with their shortcomings/risks and possible solutions/alternatives.

Precision Medicine in Pediatric Neurooncology: A Review

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

The synthesis of LA-Fe3O4@PDA-PEG-DOX for photothermal therapy–chemotherapy

The improved cell uptake and the synergistic effect of chemo-/photothermal therapy ensure the enhanced specific cytotoxicity toward HepG2 cells.

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

In order to translate nanotechnology into medical practice, magnetic nanoparticles (MNPs) have been presented as a class of non-invasive nanomaterials for numerous biomedical applications. In particular, MNPs have opened a door for simultaneous diagnosis and brisk treatment of diseases in the form of theranostic agents. This review highlights the recent advances in preparation and utilization of MNPs from the synthesis and functionalization steps to the final design consideration in evading the body immune system for therapeutic and diagnostic applications with addressing the most recent examples of the literature in each section. This study provides a conceptual framework of a wide range of synthetic routes classified mainly as wet chemistry, state-of-the-art microfluidic reactors, and biogenic routes, along with the most popular coating materials to stabilize resultant MNPs. Additionally, key aspects of prolonging the half-life of MNPs via overcoming the sequential biological barriers are covered through unraveling the biophysical interactions at the bio-nano interface and giving a set of criteria to efficiently modulate MNPs' physicochemical properties. Furthermore, concepts of passive and active targeting for successful cell internalization, by respectively exploiting the unique properties of cancers and novel targeting ligands are described in detail. Finally, this study extensively covers the recent developments in magnetic drug targeting and hyperthermia as therapeutic applications of MNPs. In addition, multi-modal imaging via fusion of magnetic resonance imaging, and also innovative magnetic particle imaging with other imaging techniques for early diagnosis of diseases are extensively provided.

Peptide-functionalized nanoparticles for the selective induction of apoptosis in target cells

AIM

The study developed a prohibitin (PHB) targeted nanotherapy for selective induction of apoptosis in target cells.

METHODS

Gold nanoparticles (AuNPs) were bifunctionalized with adipose homing and proapoptotic peptides. The efficacy and mode of cell death induced by the AuNPs were investigated in vitro on three cancer cell lines.

RESULTS

The antiproliferative activity of PHB-targeted bifunctionalized AuNPs was more pronounced on cells that express the PHB receptor, and demonstrated receptor-mediated targeting and selectivity. The bifunctionalized AuNPs induced cell death by apoptosis.

CONCLUSION

The PHB-targeted nanotherapy under study could potentially be used for treatment of diseases that are characterized by overexpression of PHB. As such, further investigations will be conducted in vivo.

Aptamer-Conjugated Chitosan-Anchored Liposomal Complexes for Targeted Delivery of Erlotinib to EGFR-Mutated Lung Cancer Cells

Lung cancer is the leading cancer and has the highest death rate. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) erlotinib has had a promising response in lung cancer therapy. Unfortunately, individuals with TKI-resistant EGFR mutations often develop acquired resistance against erlotinib. To overcome this resistance, in the present study, we developed liposomes anchored with anti-EGFR aptamer (Apt)-conjugated chitosan (Apt-Cs) as stable carriers to deliver erlotinib to the target. We loaded erlotinib into Apt-Cs-anchored liposomal complexes (Apt-CL-E) and characterized the physicochemistry of Apt-CL-E. The nanoparticles showed good biostability and a binding specificity for EGFR-mutated cancer cells guided by the Apt. The specific binding facilitated the uptake of Apt-CL-E into EGFR-mutated cancer cells. A cytotoxicity study showed an advantage of Apt-CL-E over their nontargeted liposomal counterparts in delivering erlotinib to EGFR-mutated cancer cells, resulting in cell cycle arrest and apoptosis. These results provide a good platform for future in vivo animal studies with Apt-CL-E.

The shape effect of magnetic mesoporous silica nanoparticles on endocytosis, biocompatibility and biodistribution

Although the aspect ratio (AR) play a crucial role in determining biological effects of homogeneous nanomaterials, studies available concerning how the shape contributes to biological effect of heterogeneous nanomaterials is limited. To systematically clarify the shape influence on the endocytosis, biocompatibility and biodistribution of magnetic mesoporous silica nanoparticles (M-MSNPs), three FITC-labeled M-MSNPs with different aspect ratio (AR=1, 2, and 4) were specifically designed and constructed through altering the ratios of CTAB/TEOS in a modified so-gel method. We have demonstrated that long-rod M-MSNP2 possessed higher intracellular internalization amount than the short-rod M-MSNP1 and the sphere-like M-MSNP0 in both cancer cells and normal cells due to the difference in the endocytosis pathways. However, there are no significant shape effects on biocompatibility including cytotoxicity and hemolytic rate. Moreover, biodistribution in HepG2 tumor-bearing mice showed that M-MSNPs administrated intravenously were mainly presented in reticuloendothelial system (RES) organs including liver, spleen and kidney. In particular, sphere-like M-MSNP0 were easily trapped in the liver, while long-rod M-MSP2 exhibited more retention in the spleen. It is worth noting that rod-like M-MSNPs are preferentially accumulated in tumor sites than sphere-like M-MSNPs, indicating an improved drug delivery efficacy in cancer therapy. Our findings may provide useful data for deeply understanding the interaction between the different shapes and biological behavior of M-MSNPs, which is expected to give rise to a new generation of heterogeneous M-MSNPs with significantly enhanced efficacy and safety for the cancer theranostics.

STATEMENT OF SIGNIFICANCE

In this work, we systematically clarified the shape influence on the endocytosis, biocompatibility and biodistribution of homogeneous nanomaterials. We have demonstrated that rod-like magnetic mesoporous silica nanoparticles (M-MSNPs) were capable of higher intracellular internalization and tumor accumulation than sphere-like M-MSNPs, which was expected to give rise to a new generation of heterogeneous M-MSNPs with significantly enhanced efficacy and safety for the cancer theranostics.

Allosteric DNA nanoswitches for controlled release of a molecular cargo triggered by biological inputs

A rationally designed new class of DNA-based nanoswitches allosterically regulated by specific biological targets, antibodies and transcription factors, can load and release a molecular cargo in a controlled fashion.

Here we demonstrate the rational design of a new class of DNA-based nanoswitches which are allosterically regulated by specific biological targets, antibodies and transcription factors, and are able to load and release a molecular cargo (i.e. doxorubicin) in a controlled fashion. In our first model system we rationally designed a stem-loop DNA-nanoswitch that adopts two mutually exclusive conformations: a “Load” conformation containing a doxorubicin-intercalating domain and a “Release” conformation containing a duplex portion recognized by a specific transcription-factor (here Tata Binding Protein). The binding of the transcription factor pushes this conformational equilibrium towards the “Release” state thus leading to doxorubicin release from the nanoswitch. In our second model system we designed a similar stem-loop DNA-nanoswitch for which conformational change and subsequent doxorubicin release can be triggered by a specific antibody. Our approach augments the current tool kit of smart drug release mechanisms regulated by different biological inputs.

Aptamer-Functionalized Nanoparticles as "Smart Bombs": The Unrealized Potential for Personalized Medicine and Targeted Cancer Treatment

Conventional delivery of chemotherapeutic agents leads to multiple systemic side effects and toxicity, limiting the doses that can be used. The development of targeted therapies to selectively deliver anti-cancer agents to tumor cells without damaging neighboring unaffected cells would lead to higher effective local doses and improved response rates. Aptamers are single-stranded oligonucleotides that bind to target molecules with both high affinity and high specificity. The high specificity exhibited by aptamers promotes localization and uptake by specific cell populations, such as tumor cells, and their conjugation to anti-cancer drugs has been explored for targeted therapy. Advancements in the development of polymeric nanoparticles allow anti-cancer drugs to be encapsulated in protective nonreactive shells for controlled drug delivery with reduced toxicity. The conjugation of aptamers to nanoparticle-based therapeutics may further enhance direct targeting and personalized medicine. Here we present how the combinatorial use of aptamer and nanoparticle technologies has the potential to develop "smart bombs" for targeted cancer treatment, highlighting recent pre-clinical studies demonstrating efficacy for the direct targeting to particular tumor cell populations. However, despite these pre-clinical promising results, there has been little progress in moving this technology to the bedside.

Selectively Sensitizing Malignant Cells to Photothermal Therapy Using a CD44-Targeting Heat Shock Protein 72 Depletion Nanosystem

Selectively enhance the therapeutic efficacy to malignancy is one of the most important issues for photothermal therapy (PTT). However, most solid tumors, such as triple negative breast cancer (TNBC), do not have identifiable surface markers to distinguish themselves from normal cells, thus it is challenging to selectively identify and eliminate those malignances by PTT. In this report, we hypothesized that, by targeting CD44 (one TNBC-overexpressed surface molecule) and depleting heat shock protein 72 (HSP72, one malignancy-specific-overexpressed thermotolerance-related chaperone) subsequently, the TNBC could be selectively sensitized to PTT and improve the accuracy of treatment. To this end, a rationally designed nanosystem gold nanostar (GNS)/siRNA against HSP72 (siHSP72)/hyaluronic acid (HA) was successfully constructed using a layer-by-layer method. Hydrodynamic diameter and zeta potential analysis demonstrated the formation of GNS/siHSP72/HA having a particle size of 73.2 ± 3.8 nm and a negative surface charge of -18.3 ± 1.6 mV. The CD44-targeting ability of GNS/siHSP72/HA was confirmed by the flow cytometer, confocal microscopic imaging, and competitive binding analysis. The HSP72 silencing efficacy of GNS/siHSP72/HA was ∼95% in complete culture medium. By targeting CD44 and depleting HSP72 sequentially, GNS/siHSP72/HA could selectively sensitize TNBC cells to hyperthermia and enhance the therapeutic efficacy to TNBC with minimal side effect both in vitro and in vivo. Other advantages of GNS/siHSP72/HA included easy synthesis, robust siRNA loading capacity, endosome/lysosome escaping ability, high photothermal conversion efficacy and superior hemo- and biocompatibility.

Synthetic multivalency for biological applications

Current directions and emerging possibilities under investigation for the integration of synthetic and semi-synthetic multivalent architectures with biology are discussed. Attention is focussed around multivalent interactions, their fundamental role in biology, and current and potential approaches in emulating them in terms of structure and functionality using synthetic architectures.

Viral and Synthetic RNA Vector Technologies and Applications

Use of RNA is an increasingly popular method to transiently deliver genetic information for cell manipulation in basic research and clinical therapy. In these settings, viral and nonviral RNA platforms are employed for delivery of small interfering RNA and protein-coding mRNA. Technological advances allowing RNA modification for increased stability, improved translation and reduced immunogenicity have led to increased use of nonviral synthetic RNA, which is delivered in naked form or upon formulation. Alternatively, highly efficient viral entry pathways are exploited to transfer genes of interest as RNA incorporated into viral particles. Current viral RNA transfer technologies are derived from Retroviruses, nonsegmented negative-strand RNA viruses or positive-stranded Alpha- and Flaviviruses. In retroviral particles, the genes of interest can either be incorporated directly into the viral RNA genome or as nonviral RNA. Nonsegmented negative-strand virus-, Alpha- and Flavivirus-derived vectors support prolonged expression windows through replication of viral RNA encoding genes of interest. Mixed technologies combining viral and nonviral components are also available. RNA transfer is ideal for all settings that do not require permanent transgene expression and excludes potentially detrimental DNA integration into the target cell genome. Thus, RNA-based technologies are successfully applied for reprogramming, transdifferentiation, gene editing, vaccination, tumor therapy, and gene therapy.