Aptamer-nanoparticle bioconjugates enhance intracellular delivery of vinorelbine to breast cancer cells

Activable Photodynamic DNA Probe with an "AND" Logic Gate for Precision Skin Cancer Therapy

Photodynamic therapy (PDT) has emerged as a promising approach for squamous cell carcinoma treatment but hindered by tumor hypoxia, acquired resistance, phototoxicity, and so on. To address these issues, we developed a smart strategy utilizing activable photosensitizers delivered by an aptamer-functionalized DNA probe (ADP). The ADP incorporated an AS1411 aptamer for tumor targeting and a linear antisense oligonucleotide (ASO) for recognition of Survivin mRNA. In the absence of the target, PDT remained quenched, thereby avoiding phototoxicity during circulation and nonselective distribution. With the aid of the aptamer, ADP achieved selective targeting of tumors. Upon internalization, ADP targeted recognized Survivin mRNA, triggering PDT activation, and releasing ASO to down-regulate Survivin expression and reverse tumor resistance. Consequently, the activable photosensitizers exhibited an "AND" logic gate, combining tumor-targeting delivery and tumor-related gene activation, thus enhancing its specificity. Additionally, the incorporation of hemin into the ADP provided catalase activity, converting tumor-abundant H2O2 into O2, thereby ameliorating tumor hypoxia. The resulting functionalized G-quadruplex/hemin-DNA probe complex demonstrated targeted delivery and activation, minimized side effects, and enhanced PDT efficacy in both xenograft tumor-bearing mice and patient-derived xenograft models. This study offers a unique and promising platform for efficient and safe PDT, thus holding great potential for future clinical translation and improved cancer therapy.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

Poly-thymine DNA templated MnO2 biomineralization as a high-affinity anchoring enabling tumor targeting delivery

Manganese oxide nanomaterials (MONs) are emerging as a type of highly promising nanomaterials for diseases diagnosis, and surface modification is the basis for colloidal stability and targeting delivery of the nanomaterials. Here, we report the in-situ functionalization of MnO₂ with DNA through a biomineralization process. Using adsorption-oxidation method, DNA templated Mn²⁺ precursor to biomineralize into nano-cubic seed, followed by the growth of MnO₂ to form cube/nanosheet hybrid nanostructure. Among four types of DNA homopolymers, poly-thymine (poly-T) was found to stably attach on MnO₂ surface to resist various biological displacements (phosphate, serum, and complementary DNA). Capitalized on this finding, a di-block DNA was rationally designed, in which the poly-T block stably anchored on MnO₂ surface, while the AS1411 aptamer block was not only an active ligand for tumor targeting delivery, but also a carrier for photosensitizer (Ce6) loading. Upon targeting delivery into tumor cells, the MnO₂ acted as catalase-mimic nanozyme for oxygenation to sensitize photodynamic therapy, and the released Mn²⁺ triggered chemodynamic therapy via Fenton-like reaction, achieving synergistic anti-tumor effect with full biocompatibility. This work provides a simple yet robust strategy to functionalize metal oxides nanomaterials for biological applications via DNA-templated biomineralization.

Hemin-incorporating DNA nanozyme enabling catalytic oxygenation and GSH depletion for enhanced photodynamic therapy and synergistic tumor ferroptosis

Photodynamic therapy (PDT) has emerged as a promising tumor treatment method via light-triggered generation of reactive oxygen species (ROS) to kill tumor cells. However, the efficacy of PDT is usually restricted by several biological limitations, including hypoxia, excess glutathione (GSH) neutralization, as well as tumor resistance. To tackle these issues, herein we developed a new kind of DNA nanozyme to realize enhanced PDT and synergistic tumor ferroptosis. The DNA nanozyme was constructed via rolling circle amplification, which contained repeat AS1411 G quadruplex (G4) units to form multiple G4/hemin DNAzymes with catalase-mimic activity. Both hemin, an iron-containing porphyrin cofactor, and chlorine e6 (Ce6), a photosensitizer, were facilely inserted into G4 structure with high efficiency, achieving in-situ catalytic oxygenation and photodynamic ROS production. Compared to other self-oxygen-supplying tools, such DNA nanozyme is advantageous for high biological stability and compatibility. Moreover, the nanostructure could achieve tumor cells targeting internalization and intranuclear transport of Ce6 by virtue of specific nucleolin binding of AS1411. The nanozyme could catalyze the decomposition of intracellular H₂O₂ into oxygen for hypoxia relief as evidenced by the suppression of hypoxia-inducible factor-1α (HIF-1α), and moreover, GSH depletion and cell ferroptosis were also achieved for synergistic tumor therapy. Upon intravenous injection, the nanostructure could effectively accumulate into tumor, and impose multi-modal tumor therapy with excellent biocompatibility. Therefore, by integrating the capabilities of O₂ generation and GSH depletion, such DNA nanozyme is a promising nanoplatform for tumor PDT/ferroptosis combination therapy.

Polymer-based drug delivery systems for anticancer drugs: A systematic review

Recent advances in nanotechnology sciences lead to the development of new treatment approaches for various diseases such as cancer. Nanotechnology advances can potentially minimize the side effects of drugs through the employment of effective and controlled drug delivery systems (DDSs). Polymers are optimal tools providing drug delivery mechanisms through the unique features of pharmacokinetics, circulation time, biocompatibility, and biodegradability. This systematic review aimed to evaluate polymer-based DDSs for anticancer drugs and their various therapeutic applications in cancer treatment. This study was conducted with no time limitation by November 2021. Related articles were collected through a deep search in English and Persian databases of SID, MagIran, Scopus, Web Of Science (WoS), PubMed, Science Direct, and Google Scholar. Keywords included drug delivery system, anticancer agent, polymeric nanostructure-based drug delivery, polymer-based drug delivery, and polymeric system. As the results showed, polymeric nanoparticles (PNPs) have influential roles in cancer treatment than conventional chemotherapy procedures. PNPs can reduce cytotoxicity following chemotherapy drug administration, improve the solubility characteristics of these therapeutic agents and inhibit the rate of tumor growth.

Aptamer–Gemcitabine Conjugates with Enzymatically Cleavable Linker for Targeted Delivery and Intracellular Drug Release in Cancer Cells

Gemcitabine is a chemotherapeutic used clinically to treat a variety of cancers. However, because it lacks tumor cell specificity, gemcitabine may cause off-target cytotoxicity and adversely impact patients. To impart cancer cell specificity to gemcitabine and improve its therapeutic efficacy, we synthesized a unique aptamer–drug conjugate that carries a high gemcitabine payload (three molecules) via a dendrimer structure and enzymatically cleavable linkers for controlled intracellular drug release. First, linker–gemcitabinedendrimer–linker–gemcitabine products were produced, which had significantly lower cytotoxicity than an equimolar amount of free drug. Biochemical analysis revealed that lysosomal cathepsin B protease rapidly cleaved the dendritic linkers and released the conjugated gemcitabine as a free drug. Subsequently, the dendrimer–linker–gemcitabine was coupled with a cell-specific aptamer to form aptamer–gemcitabine conjugates. Functional assays confirmed that, under aptamer guidance, aptamer–gemcitabine conjugates were selectively bound to and then internalized by triple-negative breast cancer cells. Cellular therapy studies indicated that the aptamer–gemcitabine conjugates potentiated cytotoxic activity to targeted cancer cells but did not affect off-target control cells. Our study demonstrates a novel approach to aptamer-mediated targeted drug delivery that combines a high drug payload and an enzymatically controlled drug release switch to achieve higher therapeutic efficacy and fewer off-target effects relative to free-drug chemotherapy.

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.

Aptamer-mediated synthesis of multifunctional nano-hydroxyapatite for active tumour bioimaging and treatment

OBJECTIVES

The nano-hydroxyapatite (nHAp) is widely used to develop imaging probes and drug carriers due to its excellent bioactivity and biocompatibility. However, traditional methods usually need cumbersome and stringent conditions such as high temperature and post-modification to prepare the functionalized nHAp, which do not benefit the particles to enter cells due to the increased particle size. Herein, a biomimetic synthesis strategy was explored to achieve the AS1411-targeted tumour dual-model bioimaging using DNA aptamer AS1411 as a template. Then, the imaging properties and the biocompatibility of the synthesized AS-nFAp:Gd/Tb were further investigated.

MATERIALS AND METHODS

The AS-nFAp:Gd/Tb was prepared under mild conditions through a one-pot procedure with AS1411 as a template. Besides, the anticancer drug DOX was loaded to AS-nFAp:Gd/Tb so as to achieve the establishment of a multifunctional nano-probe that integrated the tumour diagnosis and treatment. The AS-nFAp:Gd/Tb was characterized by transmission electron microscopy (TEM), energy disperse X-ray Spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) spectrum, X-ray diffraction (XRD), fourier-transformed infrared (FTIR) spectroscopy, capillary electrophoresis analyses, zeta potential and particle sizes. The in vitro magnetic resonance imaging (MRI) and fluorescence imaging were performed on an MRI system and a confocal laser scanning microscope, respectively. The potential of the prepared multifunctional nHAp for a targeted tumour therapy was investigated by a CCK-8 kit. And the animal experiments were conducted on the basis of the guidelines approved by the Animal Care and Use Committee of Sichuan University, China.

RESULTS

In the presence of AS1411, the as-prepared AS-nFAp:Gd/Tb presented a needle-like morphology with good monodispersity and improved imaging performance. Furthermore, due to the specific binding between AS1411 and nucleolin up-expressed in cancer cells, the AS-nFAp:Gd/Tb possessed excellent AS1411-targeted fluorescence and MRI imaging properties. Moreover, after loading chemotherapy drug DOX, in vitro and in vivo studies showed that DOX@AS-nFAp:Gd/Tb could effectively deliver DOX to tumour tissues and exert a highly effective tumour inhibition without systemic toxicity compared with pure DOX.

CONCLUSIONS

The results indicated that the prepared multifunctional nHAp synthesized by a novel biomimetic strategy had outstanding capabilities of recognition and treatment for the tumour and had good biocompatibility; hence, it might have a potential clinical application in the future.

AS1411-functionalized delivery nanosystems for targeted cancer therapy

Nucleolin (NCL) is a multifunctional nucleolar phosphoprotein harboring critical roles in cells such as cell proliferation, survival, and growth. The dysregulation and overexpression of NCL are related to various pathologic and oncological indications. These characteristics of NCL make it an ideal target for the treatment of various cancers. AS1411 is a synthetic quadruplex-forming nuclease-resistant DNA oligonucleotide aptamer which shows a considerably high affinity for NCL, therefore, being capable of inducing growth inhibition in a variety of tumor cells. The high affinity and specificity of AS1411 towards NCL make it a suitable targeting tool, which can be used for the functionalization of therapeutic payloaddelivery nanosystems to selectively target tumor cells. This review explores the advances in NCL-targeting cancer therapy through AS1411-functionalized delivery nanosystems for the selective delivery of a broad spectrum of therapeutic agents.

Improved Safety and Anti-Glioblastoma Efficacy of CAT3-Encapsulated SMEDDS through Metabolism Modification

13a-(S)-3-pivaloyloxyl-6,7-dimethoxyphenanthro(9,10-b)-indolizidine (CAT3) is a novel oral anti-glioma pro-drug with a potent anti-tumor effect against temozolomide-resistant glioma. 13a(S)-3-hydroxyl-6,7-dimethoxyphenanthro(9,10-b)-indolizidine (PF403) is the active in vivo lipase degradation metabolite of CAT3. Both CAT3 and PF403 can penetrate the blood-brain barrier to cause an anti-glioma effect. However, PF403, which is produced in the gastrointestinal tract and plasma, causes significant gastrointestinal side effects, limiting the clinical application of CAT3. The objective of this paper was to propose a metabolism modification for CAT3 using a self-microemulsifying drug delivery system (SMEDDS), in order to reduce the generation of PF403 in the gastrointestinal tract and plasma, as well as increase the bioavailability of CAT3 in vivo and the amount of anti-tumor substances in the brain. Thus, a CAT3-loaded self-microemulsifying drug delivery system (CAT3-SMEDDS) was prepared, and its physicochemical characterization was systematically carried out. Next, the pharmacokinetic parameters of CAT3 and its metabolite in the rats' plasma and brain were measured. Furthermore, the in vivo anti-glioma effects and safety of CAT3-SMEDDS were evaluated. Finally, Caco-2 cell uptake, MDCK monolayer cellular transfer, and the intestinal lymphatic transport mechanisms of SMEDDS were investigated in vitro and in vivo. Results show that CAT3-SMEDDS was able to form nanoemulsion droplets in artificial gastrointestinal fluid within 1 min, displaying an ideal particle size (15-30 nm), positive charge (5-9 mV), and controlled release behavior. CAT3-SMEDDS increased the membrane permeability of CAT3 by 3.9-fold and promoted intestinal lymphatic transport. Hence, the bioavailability of CAT3 was increased 79% and the level of its metabolite, PF403, was decreased to 49%. Moreover, the concentrations of CAT3 and PF403 were increased 2-6-fold and 1.3-7.2-fold, respectively, in the brain. Therefore, the anti-glioma effect in the orthotopic models was improved with CAT3-SMEDDS compared with CAT3 in 21 days. Additionally, CAT3-SMEDDS reduced the gastrointestinal side effects of CAT3, such as severe diarrhea, necrosis, and edema, and observed less inflammatory cell infiltration in the gastrointestinal tract, compared with the bare CAT3. Our work reveals that, through the metabolism modification effect, SMEDDS can improve the bioavailability of CAT3 and reduce the generation of PF403 in the gastrointestinal tract and plasma. Therefore, it has the potential to increase the anti-glioma effect and reduce the gastrointestinal side effects of CAT3 simultaneously.

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.

Aptamer-Based Targeted Drug Delivery Systems: Current Potential and Challenges

Aptamers are single-stranded DNA or RNA with 20-100 nucleotides in length that can specifically bind to target molecules via formed three-dimensional structures. These innovative targeting molecules have attracted an increasing interest in the biomedical field. Compared to traditional protein antibodies, aptamers have several advantages, such as small size, high binding affinity, specificity, good biocompatibility, high stability and low immunogenicity, which all contribute to their wide application in the biomedical field. Aptamers can bind to the receptors on the cell membrane and mediate themselves or conjugated nanoparticles to enter into cells. Therefore, aptamers can be served as ideal targeting ligands for drug delivery. Since their excellent properties, different aptamer-mediated drug delivery systems had been developed for cancer therapy. This review provides a brief overview of recent advances in drug delivery systems based on aptamers. The advantages, challenges and future prospectives are also discussed.

Tumor microenvironment and NIR laser dual-responsive release of berberine 9-O-pyrazole alkyl derivative loaded in graphene oxide nanosheets for chemo-photothermal synergetic cancer therapy

A berberine 9-O-pyrazole alkyl derivative, a chemical compound (called B3) previously synthesized by our group, shows anti-cancer activity. However, B3 lacks targeting cytotoxicity to cancer cells, leading to obvious toxic side effects on normal cells. To solve this problem, here, we prepared a drug delivery system, namely, AS1411-GO/B3 for tumor targeting, in which nano-graphene oxide (GO) sheets were employed as the drug carrier, and the aptamer AS1411 was conjugated onto GO for tumor targeting. GO also had a photothermal effect, which helped the release of B3 from GO as well as the thermal cytotoxicity to cells. We found that the release of B3 could respond to acid conditions, indicating that the tumor intracellular environment could promote the release of B3, thus allowing it to perform chemotherapy effects. This system could also release B3 in response to photothermal heating, moreover, combined photothermal therapy and chemotherapy to improve the anticancer activity was achieved. This AS1411-GO/B3 platform with chemo-photothermal synergetic therapy provides a very promising treatment for tumors.

Nucleic Acid Aptamer: A Novel Potential Diagnostic and Therapeutic Tool for Leukemia

Leukemia immunotherapy has been dominant via using synthetic antibodies to target cluster of differentiation (CD) molecules, nevertheless inevitable cytotoxicity and immunogenicity would limit its development. Recently, increasing reports have focused on nucleic acid aptamers, a class of high-affinity nucleic acid ligands. Aptamers purportedly serve as “chemical antibodies”, have negligible cytotoxicity and low immunogenicity, and would be widely applied for the therapy and diagnosis of various diseases, especially leukemia. In the preclinical applications, nucleic acid aptamers have displayed the augmented specificity and selectivity via recognizing targets on leukemia cells based on unique three-dimensional conformations. As small molecules with nucleic acid characteristics, aptamers need to be chemically modified to resist nuclease degradation, renal clearance and improve binding affinities. Moreover, aptamers can be linked with neoteric detection techniques to enhance sensitivity and selectivity of diagnosis and therapy. In this review, we summarized aptamers’ preparation, chemical modification and conjugation, and discussed the application of aptamers in diagnosis and treatment of leukemia through highly specifically recognizing target molecules. Significantly, the application prospect of aptamers in fusion genes would be introduced.

Spermine modified polymeric micelles with pH-sensitive drug release for targeted and enhanced antitumor therapy

Tumor targeting delivery of chemotherapeutic drugs by nanocarriers has been demonstrated to be a promising strategy for cancer therapy with improved therapeutic efficacy. In this work, we reported a novel type of active targeting micelle with pH-responsive drug release by using biodegradable poly(lactide)-poly(2-ethyl-2-oxazoline) di-block copolymers functionalized with spermine (SPM). SPM has been considered as a tumor binding ligand through its specific interaction with the polyamine transport system (PTS), a transmembrane protein overexpressed on various types of cancer cell, while its application in nano-drug delivery systems has rarely been explored. The micelles with spherical shape (∼110 nm) could load hydrophobic paclitaxel (PTX) with high capacity, and release the payload much faster at acidic pH (4.5–6.5) than at pH 7.4. This pH-responsive property assisted the rapid escape of drug from the endo/lysosome after internalization as demonstrated by confocal laser scanning microscopy images using coumarin-6 (Cou-6) as a fluorescent probe. With surface SPM modification, the micelles displayed much higher cellular uptake than SPM lacking micelles in various types of cancer cells, demonstrating tumor targeting ability. The uptake mechanism of SPM modified micelles was explored by flow cytometry, which suggested an energy-consuming sag vesicle-mediated endocytosis pathway. As expected, the micelles displayed significantly enhanced anti-cancer activity. This work demonstrates that SPM modified pH-sensitive micelles may be potential drug delivery vehicles for targeting and effective cancer therapy.

Tumor targeting delivery of SPM functionalized micelles via PTS binding and their endocytosis and pH-triggered endo/lysosome drug release for anti-cancer therapy.

Oligonucleotide Aptamer-Mediated Precision Therapy of Hematological Malignancies

Precision medicine has recently emerged as a promising strategy for cancer therapy because it not only specifically targets cancer cells but it also does not have adverse effects on normal cells. Oligonucleotide aptamers are a class of small molecule ligands that can specifically bind to their targets on cell surfaces with high affinity. Aptamers have great potential in precision cancer therapy due to their unique physical, chemical, and biological properties. Therefore, aptamer technology has been widely investigated for biomedical and clinical applications. This review focuses on the potential applications of aptamer technology as a new tool for precision treatment of hematological malignancies, including leukemia, lymphoma, and multiple myeloma.

TNBC Challenge: Oligonucleotide Aptamers for New Imaging and Therapy Modalities

Compared to other breast cancers, triple-negative breast cancer (TNBC) usually affects younger patients, is larger in size, of higher grade and is biologically more aggressive. To date, conventional cytotoxic chemotherapy remains the only available treatment for TNBC because it lacks expression of the estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2), and no alternative targetable molecules have been identified so far. The high biological and clinical heterogeneity adds a further challenge to TNBC management and requires the identification of new biomarkers to improve detection by imaging, thus allowing the specific treatment of each individual TNBC subtype. The Systematic Evolution of Ligands by EXponential enrichment (SELEX) technique holds great promise to the search for novel targetable biomarkers, and aptamer-based molecular approaches have the potential to overcome obstacles of current imaging and therapy modalities. In this review, we highlight recent advances in oligonucleotide aptamers used as imaging and/or therapeutic agents in TNBC, discussing the potential options to discover, image and hit new actionable targets in TNBC.

Targeted cancer drug delivery with aptamer-functionalized polymeric nanoparticles

Based on exceptional advantages of aptamers, increasing attention has been presented in the utilise of them as targeted ligands for cancer drug delivery. Recently, the progress of aptamer-targeted nanoparticles has presented new therapeutic systems for several types of cancer with decreased toxicity and improved efficacy. We highlight some of the promising formulations of aptamer-conjugated polymeric nanoparticles for specific targeted drug delivery to cancer cells. This review paper focuses on the current progresses in the use of the novel strategies to aptamer-targeted drug delivery for chemotherapy. An extensive literature review was performed using internet database, mainly PubMed based on MeSH keywords. The searches included full-text publications written in English without any limitation in date. The abstracts, reviews, books as well as studies without obvious relating of aptamers as targeted ligands for cancer drug delivery were excluded from the study. The reviewed literature revealed that aptamers with ability to modify and conjugate to various molecules can be used as targeted cancer therapy agents. However, development of aptamers unique to each individual's tumour to the development of personalised medicine seems to be needed.

Cancer nanomedicine: mechanisms, obstacles and strategies

Targeting nanoparticles to cancers for improved therapeutic efficacy and decreased side effects remains a popular concept in the past decades. Although the enhanced permeability and retention effect serves as a key rationale for all the currently commercialized nanoformulations, it does not enable uniform delivery of nanoparticles to all tumorous regions in all patients with sufficient quantities. Also, the increase in overall survival is often modest. Many factors may influence the delivering process of nanoparticles, which must be taken into consideration for the promise of nanomedicine in patients to be realized. Herein, we review the mechanisms and influencing factors during the delivery of cancer therapeutics and summarize current strategies that have been developed for the fabrication of smart drug delivery systems.

Meeting the needs of breast cancer: A nucleolin's perspective

A major challenge in the management of breast cancer disease has been the development of metastases. Finding new molecular targets and the design of targeted therapeutic approaches to improve the overall survival and quality of life of these patients is, therefore, of great importance. Nucleolin, which is overexpressed in cancer cells and tumor-associated blood vessels, have been implicated in various processes supporting tumorigenesis and angiogenesis. Additionally, its overexpression has been demonstrated in a variety of human neoplasias as an unfavorable prognostic factor, associated with a high risk of relapse and low overall survival. Hence, nucleolin has emerged as a relevant target for therapeutic intervention in cancer malignancy, including breast cancer. This review focus on the contribution of nucleolin for cancer disease and on the development of therapeutic strategies targeting this protein. In this respect, it also provides a critical analysis about the potential and pitfalls of nanomedicine for cancer therapy.

Carboxyl of Poly(D,L-lactide-co-glycolide) Nanoparticles of Perfluorooctyl Bromide for Ultrasonic Imaging of Tumor

Perfluorooctyl bromide (PFOB) enclosed nanoparticles (NPs) as ultrasonic contrasts have shown promising results in the recent years. However, NPs display poor contrast enhancement in vivo. In this work, we used the copolymers poly(lactide-co-glycolide) carboxylic acid (PLGA-COOH) and poly(lactide-co- glycolide) poly(ethylene glycol) carboxylic acid (PLGA-PEG-COOH) as a shell to encapsulate PFOB to prepare a nanoultrasonic contrast agent. The NPs were small and uniform (210.6 ± 2.9 nm with a polydispersity index of 0.129 ± 0.016) with a complete shell nuclear structure under the transmission electron microscopy (TEM). In vitro, when concentration of NPs was ≥10 mg/ml and clinical diagnostic frequency was ≥9 MHz, NPs produced intensive enhancement of ultrasonic gray-scale signals. NPs could produce stable and obvious gray enhancement with high mechanical index (MI) (MI > 0.6). In vivo, the NPs offered good ultrasound enhancement in tumor after more than 24 h and optical imaging also indicated that NPs were mainly located at tumor site. Subsequent analysis confirmed that large accumulation of fluorescence was observed in the frozen section of the tumor tissue. All these results caused the conclusion that NPs encapsulated PFOB has achieved tumor-selective imaging in vivo.

Facile construction of dual-targeting delivery system by using lipid capped polymer nanoparticles for anti-glioma therapy

A facile and reliable platform to construct dual targeting nanoparticles for glioma treatment, and the targeting efficiency was demonstrated.

Effect of Surface Modification on the In vitro Protein Adsorption and Cell Cytotoxicity of Vinorelbine Nanoparticles

Context:

Nanocarriers possessing long-circulating abilities could take advantage of the pathophysiology of tumor vasculature to achieve spatial placement. To attain such qualities, the drug carriers should possess suitable physicochemical properties such as size and surface hydrophilicity.

Aim:

The aim of this study was to prepare poly(ε-caprolactone) nanoparticles (NPs) loaded with vinorelbine bitartrate (VB) and to modify its steric properties using polyethylene glycol and poloxamer. Furthermore, the influence of surface modification of NPs on their physicochemical and cell interactive properties was evaluated.

Materials and Methods:

NPs were prepared by double emulsion solvent extraction–evaporation technique. The prepared NPs were evaluated for their physicochemical properties, in vitro protein adsorption and cell cytotoxicity.

Results and Discussion:

The NPs were <250 nm with an entrapment efficiency ranging between 40% and 52%. The zeta potential of the NPs varied from −7.52 mV to −1.27 mV depending on the surface modification. The in vitro release studies exhibited a biphasic pattern with an initial burst release followed by controlled release of the drug over 72 h. The protein adsorption studies revealed that the ability to resist protein adsorption was influenced by the concentration of surface-modifying agents and the amount of proteins available for interaction. The surface-modified NPs produced cell cytotoxicity comparable to free VB at higher concentrations owing to sustained release of the drug into the cellular environment.

Conclusion:

The results emphasize that surface modification of nanocarriers is an essential and effective tool to dodge opsonization and phagocytosis in the physiological milieu.

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.

Hyaluronic acid conjugated micelles possessing CD44 targeting potential for gene delivery

The high- and low-molecular weight hyaluronic acid (HHA and LHA) were used to conjugate with PLGA-PEG copolymers which were applied to encapsulate DOTAP/pDNA (D/P) lipoplex as a CD44-targeted micelle delivery system. The size and zeta potential of DNA loaded micelles were measured. The cytotoxicity and cellular transfection of DNA loaded micelles were performed in CD44-positive MDA-MB-231 and MCF-7 cancer cells and CD44-negative HepG2 cells. The endocytosis mechanism of micelles was investigated further. The DNA loaded HA-conjugated micelles possessed negative-charged character which prevented erythrocytes from agglutination. Both LHA-PEG-PLGA and HHA-PEG-PLGA micelles had comparable cellular viability in L929 normal cells. The cellular transfection of HHA-PEG-PLGA micelles was much higher than of LHA-PEG-PLGA micelles in CD44-positive cells. The specific and strong binding of HHA to CD44-positive cells resulted in the cellular transfection of HHA-PEG-PLGA micelles in CD44-positive cells significantly higher than in CD44-negative cells.

Aptamers: A promising chemical antibody for cancer therapy

Aptamers, also known as chemical antibodies, are single-stranded nucleic acid oligonucleotides which bind to their targets with high specificity and affinity. They are typically selected by repetitive in vitro process termed systematic evolution of ligands by exponential enrichment (SELEX). Owing to their excellent properties compared to conventional antibodies, notably their smaller physical size and lower immunogenicity and toxicity, aptamers have recently emerged as a new class of agents to deliver therapeutic drugs to cancer cells by targeting specific cancer-associated hallmarks. Aptamers can also be structurally modified to make them more flexible in order to conjugate other agents such as nano-materials and therapeutic RNA agents, thus extending their applications for cancer therapy. This review presents the current knowledge on the practical applications of aptamers in the treatment of a variety of cancers.

Drug delivery systems and combination therapy by using vinca alkaloids

Developing new methods for chemotherapy drug delivery has become a topic of great concern. Vinca alkaloids are among the most widely used chemotherapy reagents for tumor therapy; however, their side effects are particularly problematic for many medical doctors. To reduce the toxicity and enhance the therapeutic efficiency of vinca alkaloids, many researchers have developed strategies such as using liposome-entrapped drugs, chemical- or peptide-modified drugs, polymeric packaging drugs, and chemotherapy drug combinations. This review mainly focuses on the development of a vinca alkaloid drug delivery system and the combination therapy. Five vinca alkaloids (eg, vincristine, vinblastine, vinorelbine, vindesine, and vinflunine) are reviewed.

Polydopamine-Based Surface Modification of Novel Nanoparticle-Aptamer Bioconjugates for In Vivo Breast Cancer Targeting and Enhanced Therapeutic Effects

In this study, we reported a simple polydopamine (pD)-based surface modification method to prepare novel nanoparticle-aptamer bioconjugates (Apt-pD-DTX/NPs) for in vivo tumor targeting and enhanced therapeutic effects of breast cancer. With simple preparation procedures, the new functionalized Apt-pD-DTX/NPs could maximumly increase the local effective drug concentration on tumor sites, achieving enhanced treatment effectiveness and minimizing side effects. The dopamine polymerization and aptamer conjugation barely changed the characters of NPs. Both in vitro cell experiments (i.e. endocytosis of fluorescent NPs, in vitro cellular targeting and cytotoxicity assays) and in vivo animal studies (i.e. in vivo imaging, biodistribution and antitumor effects of NPs) demonstrated that the Apt-pD-DTX/NPs could achieve significantly high targeting efficiency and enhanced therapeutic effects compared with clinical Taxotere(®) and NPs without functional modification. Above all, the Apt-pD-DTX/NPs showed great potential as a promising nanoformulation for in vivo breast cancer therapy and the construction of pD-modified NP-aptamer bioconjugates could be of great value in medical use.

Aptamer application in targeted delivery systems for diagnosis and treatment of breast cancer

In this review, we present the recent progress of aptamer application in targeted delivery systems for imaging and treatment of breast cancer.

Breast Cancer: Conventional Diagnosis and Treatment Modalities and Recent Patents and Technologies

Breast cancer is the most prevalent cancer among women worldwide. However, increased survival is due to the dramatic advances in the screening methods, early diagnosis, and breakthroughs in treatments. Over the course of the last decade, many acquisitions have taken place in this critical field of research in the pharmaceutical industry. Advances in molecular biology and pharmacology aided in better understanding of breast cancer, enabling the design of smarter therapeutics able to target cancer and respond to its microenvironment efficiently. Patents and research papers investigating diagnosis and treatment strategies for breast cancer using novel technologies have been surveyed for the past 15 years. Various nanocarriers have been introduced to improve the therapeutic efficacy of anticancer drugs, including liposomes, polymeric micelles, quantum dots, nanoparticles, and dendrimers. This review provides an overview of breast cancer, conventional therapy, novel technologies in the management of breast cancer, and rational approaches for targeting breast cancer.

HIGHLIGHTS

Breast cancer is the most common cancer in women worldwide. However, survival rates vary widely, optimistically heading toward a positive trend. Increased survival is due to the drastic shift in the screening methods, early diagnosis, and breakthroughs in treatments.Different strategies of breast cancer classification and staging have evolved over the years. Intrinsic (molecular) subtyping is essential in clinical trials and well understanding of the disease.Many novel technologies are being developed to detect distant metastases and recurrent disease as well as to assess response to breast cancer management.Intensive research efforts are actively ongoing to take novel breast cancer therapeutics to potential clinical application.Most of the recent research papers and patents discuss one of the following strategies: the development of new drug entities that specifically target the breast tumor cells; tailor designing a novel carrier system that can multitask and multifunction as a drug carrier, targeting vehicle and even as a diagnostic tool, direct conjugation of a therapeutic drug moiety with a targeting moiety, diagnostic moiety or pharmacokinetics altering moiety; or the use of innovative nontraditional approaches such as genetic engineering, stem cells, or vaccinations.

Design of liposomal formulations for cell targeting

Liposomes have gained extensive attention as carriers for a wide range of drugs due to being both nontoxic and biodegradable as they are composed of substances naturally occurring in biological membranes. Active targeting for cells has explored specific modification of the liposome surface by functionalizing it with specific targeting ligands in order to increase accumulation and intracellular uptake into target cells. None of the Food and Drug Administration-licensed liposomes or lipid nanoparticles are coated with ligands or target moieties to delivery for homing drugs to target tissues, cells or subcellular organelles. Targeted therapies (with or without controlled drug release) are an emerging and relevant research area. Despite of the numerous liposomes reviews published in the last decades, this area is in constant development. Updates urgently needed to integrate new advances in targeted liposomes research. This review highlights the evolution of liposomes from passive to active targeting and challenges in the development of targeted liposomes for specific therapies.

Strategies of polymeric nanoparticles for enhanced internalization in cancer therapy

In order to achieve long circulation time and high drug accumulation in the tumor sites via the EPR effects, anticancer drugs have to be protected by non-fouling polymers such as poly(ethylene glycol) (PEG), poly(ethylene oxide) (PEO), dextran, and poly(acrylic acid) (PAA). However, the dense layer of stealth polymer also prohibits efficient uptake of anticancer drugs by target cancer cells. For cancer therapy, it is often more desirable to accomplish rapid cellular uptake after anticancer drugs arriving at the pathological site, which could on one hand maximize the therapeutic efficacy and on the other hand reduce probability of drug resistance in cells. In this review, special attention will be focused on the recent potential strategies that can enable drug-loaded polymeric nanoparticles to rapidly recognize cancer cells, leading to enhanced internalization.

Targeted nanoparticles for image-guided treatment of triple-negative breast cancer: clinical significance and technological advances

Effective treatment of triple-negative breast cancer (TNBC) with its aggressive tumor biology, highly heterogeneous tumor cells, and poor prognosis requires an integrated therapeutic approach that addresses critical issues in cancer therapy. Multifunctional nanoparticles with the abilities of targeted drug delivery and noninvasive imaging for monitoring drug delivery and responses to therapy, such as theranostic nanoparticles, hold great promise toward the development of novel therapeutic approaches for the treatment of TNBC using a single therapeutic platform. The biological and pathological characteristics of TNBC provide insight into several potential molecular targets for current and future nanoparticle-based therapeutics. Extensive tumor stroma, highly proliferative cells, and a high rate of drug resistance are all barriers that must be appropriately addressed in order for these nanotherapeutic platforms to be effective. Utilization of the enhanced permeability and retention effect coupled with active targeting of cell surface receptors expressed by TNBC cells, and tumor-associated endothelial cells, stromal fibroblasts, and macrophages is likely to overcome such barriers to facilitate more effective drug delivery. An in-depth summary of current studies investigating targeted nanoparticles in preclinical TNBC mouse and human xenograft models is presented. This review aims to outline the current status of nanotherapeutic options for TNBC patients, identification of promising molecular targets, challenges associated with the development of targeted nanotherapeutics, the research done by our group as well as by others, and future perspectives on the nanomedicine field and ways to translate current preclinical studies into the clinic.

Aptamer density dependent cellular uptake of lipid-capped polymer nanoparticles for polyvalent targeted delivery of vinorelbine to cancer cells

In this work, MUC1 aptamer (designated S2.2) modified and vinorelbine (VRL) loaded lipid-polymer hybrid nanoparticles (Apt-VRL-NPs) were prepared.

Epithelial cell adhesion molecule aptamer conjugated PEG-PLGA nanopolymersomes for targeted delivery of doxorubicin to human breast adenocarcinoma cell line in vitro

Targeted delivery of anti-cancer agents exclusively to tumor cells introduces an attractive strategy because it increases the therapeutic index compared with untargeted drugs. Aptamer conjugated nanoparticles that can specifically bind to the proteins on a tumor cell surface are capable nanoscale delivery systems for enhancing cellular uptake of chemotherapeutic agents. The epithelial cell adhesion molecule (EpCAM) as a cancer stem cell marker emerges as a versatile target for aptamer-based cancer therapy due to its high expression level in various adenocarcinoma cell lines and its very low expression level in normal cells. We developed EpCAM-targeted PEG-PLGA nanopolymersomes by covalently coupling the EpCAM aptamer to the surface of nanopolymersomes loaded with the anticancer agent doxorubicin via pH gradient method. The results indicated that doxorubicin was entrapped in PEG-PLGA nanopolymersomes with encapsulation efficiency and loading content of 91.25±4.27% and 7.3±0.34%, respectively. Over a period of 5 days, up to 8% of the DOX was released through this system. The doxorubicin-loaded aptamer conjugated nanopolymersomes exhibited efficient cell uptake and internalization, and were significantly more cytotoxic (P<0.01) toward EpCAM-positive tumor cells (MCF-7) than non-targeted nanopolymersomes. Our data suggest that EpCAM-targeted nanopolymersomes will lead to an improved therapeutic index of doxorubicin to EpCAM positive cancer cells.