A carrier-free dual-drug nanodelivery system functionalized with aptamer specific targeting HER2-overexpressing cancer cells

Synergistic anti-tumor effect of dual drug co-assembled nanoparticles based on ursolic acid and sorafenib

Both ursolic acid (UA) and sorafenib (Sora) have been generally utilized in cancer treatment, and the combination of the two has also shown a good anti-tumor effect. However, single-agent therapy for Hepatocellular carcinoma (HCC) has the disadvantages of multi-drug resistance, poor water solubility and low bioavailability, and the application of traditional nanocarrier materials is limited due to their low drug loading and low carrier-related toxicity. Therefore, we prepared US NPs with different proportions of UA and Sora by solvent exchange method for achieving synergistic HCC therapy. US NPs had suitable particle size, good dispersibility and storage stability, which synergistically inhibited the proliferation of HepG2 cells, SMMC7721 cells and H22 cells. In addition, we also proved that US NPs were able to suppress the migration of HepG2 cells and SMMC7721 cells and reduce the adhesion ability and colony formation ability of these cells. According to the results, US NPs could degrade the membrane potential of mitochondrial, participate in cell apoptosis, and synergistically induce autophagy. Collectively, the carrier-free US NPs provide new strategies for HCC treatment and new ideas for the development of novel nano-drug delivery systems containing UA and Sora.

Ferroptosis boosted oral cancer photodynamic therapy by carrier-free Sorafenib-Ce6 self-assembly nanoparticles

Oral cancer is a disease with high morbidity and mortality worldwide and greatly impacts the quality of life, especially in patients with advanced stages. Photodynamic therapy (PDT) is one of the most effective clinical treatments for oral cancers. However, most clinically applied photosensitizers have several deficiencies, including oxygen dependence, poor aqueous solubility, and a lack of tumor-targeting ability. Herein, the carrier-free multifunctional Sorafenib (Sor), chlorin e6 (Ce6), and Fe3+ self-assembly co-delivery nanoparticles (Sor-Ce6 NPs) were constructed via combining a ferroptosis inducer Sor and a photosensitizer Ce6 for synergetic therapy. The as-synthesized Sor-Ce6 NPs presented excellent colloidal stability and water dispersity with good in vivo tumor-targeting ability. More significantly, the low dose of Sor-Ce6 NPs had little dark toxicity but produced significantly enhanced ROS and supplied O2 sustainably to increase phototoxicity through ferroptosis pathway. Notably, the Sor-Ce6 NPs showed significantly higher in vitro and in vivo anti-tumor efficacy than the Sor/Ce6 mixture due to the improvement of cellular uptake and the incorporation of foreign Fe ions in the system, which also confer the T1 magnetic resonance-guided imaging ability to the formed Sor-Ce6 NPs. Our study demonstrates a promising self-assembled strategy for overcoming hypoxia-related PDT resistance for oral cancer treatment.

HER2 aptamer-conjugated iron oxide nanoparticles with PDMAEMA-b-PMPC coating for breast cancer cell identification

Aim: To synthesize HER2 aptamer-conjugated iron oxide nanoparticles with a coating of poly(2-(dimethylamino) ethyl methacrylate)-poly(2-methacryloyloxyethylphosphorylcholine) block copolymer (IONPPPs). Methods: Characterization covered molecular structure, chemical composition, thermal stability, magnetic characteristics, aptamer interaction, crystalline nature and microscopic features. Subsequent investigations focused on IONPPPs for in vitro cancer cell identification. Results: Results demonstrated high biocompatibility of the diblock copolymer with no significant toxicity up to 150 μg/ml. The facile coating process yielded the IONPP complex, featuring a 13.27 nm metal core and a 3.10 nm polymer coating. Functionalized with a HER2-targeting DNA aptamer, IONPPP enhanced recognition in HER2-amplified SKBR3 cells via magnetization separation. Conclusion: These findings underscore IONPPP's potential in cancer research and clinical applications, showcasing diagnostic efficacy and HER2 protein targeting in a proof-of-concept approach.

Advanced cancer targeting using aptamer functionalized nanocarriers for site-specific cargo delivery

The non-specificity of standard anticancer therapies has profound detrimental consequences in clinical treatment. Therapeutic specificity can be precisely achieved using cutting-edge ligands. Small synthetic oligonucleotide-ligands chosen through Systematic evolution of ligands by exponential enrichment (SELEX) would be an unceasing innovation in using nucleic acids as aptamers, frequently referred to as "chemical antibodies." Aptamers act as externally controlled switching materials that can attach to various substrates, for example, membrane proteins or nucleic acid structures. Aptamers pose excellent specificity and affinity for target molecules and can be used as medicines to suppress tumor cell growth directly. The creation of aptamer-conjugated nanoconstructs has recently opened up innovative options in cancer therapy that are more effective and target tumor cells with minor toxicity to healthy tissues. This review focuses on a comprehensive description of the most capable classes of aptamer-tethered nanocarriers for precise recognition of cancer cells with significant development in proficiency, selectivity, and targetability for cancer therapy. Existing theranostic applications with the problems and future directions are also highlighted.

Multicomponent carrier-free nanodrugs for cancer treatment

Nanocarriers can be used to deliver insoluble anticancer drugs to optimize therapeutic efficacy. However, the potential toxicity of nanocarriers cannot be ignored. Carrier-free nanodrugs are emerging safe drug delivery systems, which are composed of multiple components, such as drugs, bioactive molecules and functional ingredients, avoiding the usage of inert carrier materials and offering advantages that include high drug loading, low toxicity, synergistic therapy, versatile design, and easy surface functionalization. Therefore, how to design multicomponent carrier-free nanodrugs is becoming a priority. In this review, the common strategies for rapid construction of multicomponent carrier-free nanodrugs are briefly explored from the perspective of methodology. The properties of organic-organic, organic-inorganic and inorganic-inorganic multiple carrier-free nanosystems are analyzed according to wettability and in-depth understanding is provided. Further advances in the applications of multiple carrier-free nanodrugs are outlined in anticipation of grasping the intrinsic nature for the design and development of carrier-free nanodrugs.

Carrier-free nanoplatforms from natural plants for enhanced bioactivity

BACKGROUND

Natural plants as well as traditional Chinese medicine have made outstanding contributions to the health and reproduction of human beings and remain the basis and major resource for drug innovation. Carrier-free nanoplatforms completely self-assembled by pure molecules or therapeutic components have attracted increasing attention due to their advantages of improved pharmacodynamics/pharmacokinetics, reduced toxicity, and high drug loading. In recent years, carrier-free nanoplatforms produced by self-assembly from natural plants have contributed to progress in a variety of therapeutic modalities. Notably, these nanoplatforms based on the interactions of components from different natural plants improve efficiency and depress toxicity.

AIM OF REVIEW

In this review, different types of self-assembled nanoplatforms are first summarized, mainly including nanoassemblies of pure small molecules isolated from different plants, extracellular vesicles separated from fresh plants, charcoal nanocomponents obtained from charred plants, and nanoaggregates from plants formulae decoctions. Key Scientific Concepts of Review: We mainly focus on composition, self-assembly mechanisms, biological activity and modes of action. Finally, a future perspective of existing challenges with respect to the clinical application of plant-based carrier-free nanoplatforms is discussed, which may be instructive to further develop effective carrier-free nanoplatforms from natural plants in the future.

Sugar-induced self-assembly of curcumin-based polydopamine nanocapsules with high loading capacity for dual drug delivery

Many drug delivery carriers reported in the literature require multistep assembly or often have very low drug loading capacities. Here, we present a simple sugar-based strategy that feeds the increased interest in high-loading nanomedicine. The driving force of the supramolecular nanocapsule formation is the interaction between curcumin (CCM) and the monosaccharide fructose. Drug and sugar are simply mixed in an aqueous solution in an open vessel, followed by coating the nanocapsules with polydopamine (PDA) to maintain structural integrity. We show that nanocapsules can still be obtained when other drugs are added, producing dual-drug nanoparticles with sizes of around 150-200 nm and drug loading contents of around 90% depending on the thickness of the PDA shell. This concept is widely applicable for a broad variety of drugs, as long as the drug has similar polarities to CCM. The key to success is the interaction of CCM and the second drug as shown in computational studies. The drug was able to be released from the nanocapsule at a release rate that could be fine-tuned by adjusting the thickness of the PDA layer.

Carrier-free nanodrugs with efficient drug delivery and release for cancer therapy: From intrinsic physicochemical properties to external modification

The considerable development of carrier-free nanodrugs has been achieved due to their high drug-loading capability, simple preparation method, and offering "all-in-one" functional platform features. However, the native defects of carrier-free nanodrugs limit their delivery and release behavior throughout the in vivo journey, which significantly compromise the therapeutic efficacy and hinder their further development in cancer treatment. In this review, we summarized and discussed the recent strategies to enhance drug delivery and release of carrier-free nanodrugs for improved cancer therapy, including optimizing the intrinsic physicochemical properties and external modification. Finally, the corresponding challenges that carrier-free nanodrugs faced are discussed and the future perspectives for its application are presented. We hope this review will provide constructive information for the rational design of more effective carrier-free nanodrugs to advance therapeutic treatment.

Biomimetic nanoparticles: U937 cell membranes based core-shell nanosystems for targeted atherosclerosis therapy

Atherosclerosis (AS), with its intricate pathogenesis, is primarily responsible for the development and progression of cardiovascular diseases. Although drug development has made some achievements in AS therapy, limited targeting ability and rapid blood clearance remain great challenges for achieving superior clinical outcomes. Herein, ginsenoside (Re)- and catalase (CAT)-coloaded porous poly(lactic-coglycolic acid) (PLGA) nanoparticles (NPs) were prepared and then surface modified with U937 cell membranes (UCMs) to yield a dual targeted model and multimechanism treatment biomimetic nanosystem (Cat/Re@PLGA@UCM). The nanoparticles consisted of a core-shell spherical morphology with a favorable size of 112.7 ± 0.4 nm. Furthermore, UCM assisted the nanosystem in escaping macrophage phagocytosis and targeting atherosclerotic plaques. Meanwhile, loading with catalase might not only exhibit favorable antioxidant effects but also enable H₂O₂-responsive drug release ability. The Cat/Re@PLGA@UCM NPs also exhibited outstanding ROS scavenging properties, downregulating ICAM-1, TNF-α and IL-1β, while preventing angiogenesis to attenuate the progression of AS. Moreover, the nanodrugs displayed 2.7-fold greater efficiency in reducing the atherosclerotic area in ApoE^-/- mouse models compared to free Re. Our nanoformulation also displayed excellent biosafety in response to long-term administration. Overall, our study demonstrated the superiority of UCM-coated stimuli-responsive nanodrugs for effective and safe AS therapy.

Delivering more for less: nanosized, minimal-carrier and pharmacoactive drug delivery systems

Traditional nanoparticle carriers such as liposomes, micelles, and polymeric vehicles improve drug delivery by protecting, stabilizing, and increasing the circulatory half-life of the encapsulated drugs. However, traditional drug delivery systems frequently suffer from poor drug loading and require an excess of carrier materials. This carrier material excess poses an additional systemic burden through accumulation, if not degradable the need for metabolism, and potential toxicity. To address these shortcomings, minimal-carrier nanoparticle systems and pharmacoactive carrier materials have been developed. Both solutions provide drug delivery systems in which the majority of the nanoparticle is pharmacologically active. While minimal-carrier and pharmacoactive drug delivery systems can improve drug loading, they can also suffer from poor stability. Here, we review minimal-carrier and pharmacoactive delivery systems, discuss ongoing challenges and outline opportunities to translate minimal-carrier and pharmacoactive drug delivery systems into the clinic.

Amphiphilic small molecular mates match hydrophobic drugs to form nanoassemblies based on drug-mate strategy

Nanomedicine has made great progress in the targeted therapy of cancer. Here, we established a novel drug-mate strategy by studying the formulation of nanodrugs at the molecular level. In the drug-mate combination, the drug is a hydrophobic drug that is poorly soluble in water, and the mate is an amphiphilic small molecule (SMA) that has both hydrophilic and lipophilic properties. We proposed that the hydrophobic drug could co-assemble with a suitable SMA on a nanoscale without additive agents. The proof-of-concept methodology and results were presented to support our hypothesis. We selected five hydrophobic drugs and more than ten amphiphilic small molecules to construct a library. Through molecular dynamic simulation and quantum chemistry computation, we speculated that the formation of nanoassemblies was related to the binding energy of the drug-mate, and the drug-mate interaction must overcome drug-drug interaction. Furthermore, the obtained SF/VECOONa nanoassemblieswas selected as a model, which had an ultra-high drug loading content (46%), improved pharmacokinetics, increased bioavailability, and enhanced therapeutic efficacy. In summary, the drug-mate strategy is an essential resource to design exact SMA for many hydrophobic drugs and provides a reference for the design of a carrier-free drug delivery system.

Biomimetic polyphenol-coated nanoparticles by Co-assembly of mTOR inhibitor and photosensitizer for synergistic chemo-photothermal therapy

Rapamycin (RAPA) functions as effectively clinical immunosuppressive agent, its significant tumor growth suppression effect via various pathways in diverse cancers, especially combined with photothermal therapy, is gaining a burgeoning attention. However, its critical defects, low solubility and poor stability, have severely hampered its further application. Herein, RAPA, indocyanine green (ICG) and epigallocatechin gallate (EGCG) serving as chemotherapeutic drug, photosensitizer and biomimetic coatings, respectively, were co-assembled into carrier-free, high biocompatible ICG-RAPA-EGCG nanoparticles (IRE NPs) for synergistic cancer therapy. Particularly, the bioinspired EGCG coatings not only improved the stability of IRE NPs under physiological conditions to avert NPs disassembly and drug release, but also maintained the photostability of ICG to achieve excellent photothermal response. The results indicated that the as-prepared IRE NPs displayed good monodispersity and enhanced stability at various stored media after introducing of EGCG. Compared with monotherapy of RAPA or ICG, IRE NPs showed higher dose-dependent toxicity in MCF-7 cells, HepG2 cells and HeLa cells, especially plus near-infrared laser irradiation. Furthermore, IRE NPs exhibited quicker uptake in cells, higher accumulation in tumor region (even in 48 h) than free ICG and effectively inhibited tumor growth without side effect in H22 tumor-bearing mice. Collectively, the carrier-free IRE NPs provided a simply alternative approach to fabricate RAPA/photosensitizer co-loaded nanoparticles for combinatorial tumor therapy.

A Carrier-Free Folate Receptor-Targeted Ursolic Acid/Methotrexate Nanodelivery System for Synergetic Anticancer Therapy

PURPOSE

To avoid undefined metabolic mechanisms and to eliminate potential side effects of traditional nanocarriers, new green carriers are urgently needed in cancer treatment. Carrier-free nanoparticles (NPs) based on ursolic acid (UA) have attracted significant attention, but the UA NPs targeting the folate receptor have never been explored. We designed a novel self-assembled UA-Methotrexate (MTX) NPs targeting the folate-receptor and its synergetic anticancer activity was studied in vitro and in vivo.

METHODS

UA-MTX NPs were prepared using the solvent precipitation method. Characterization of the UA-MTX NPs preparation was performed using a size analyzer, transmission electron microscopy, and UV-vis spectrophotometry. The in vitro pH-responsive drug release capability of UA-MTX NPs was tested at different pH values. The UA-MTX NPs targeting of folates was determined by comparing the endocytosis rates of cell lines with low or overexpression of the folate receptor (A549 and MCF-7 cells). The cytotoxicity and cell apoptosis of UA-MTX NPs were also studied to determine the in vitro synergistic effects. Combination chemotherapy of UA-MTX NPs in vivo was evaluated using MCF-7 xenografted tumor models.

RESULTS

Compared with free UA or MTX, the water solubility of UA-MTX NPs improved significantly. Drug-release from the UA-MTX NPs was faster at pH 5.0 than pH 7.4, suggesting MTX-UA NPs could rapidly release MTX in the acidic conditions of the tumor microenvironment. Confocal laser scanning microscopy revealed the excellent folate receptor targeting of UA-MTX NPs in MCF-7 cells. Cytotoxicity and cell apoptosis results demonstrated greater antiproliferative capacity of UA-MTX NPs than that of free drug in folate receptor overexpressing MCF-7 cells. Anticancer effects in vivo suggested MTX-UA NPs exhibited good biological safety and could enhance antitumor efficacy due to the combination therapy.

CONCLUSION

Our findings indicate that the UA-MTX NPs targeting folate-receptors is an efficient strategy for combination chemotherapy.

A smart dual-drug nanosystem based on co-assembly of plant and food-derived natural products for synergistic HCC immunotherapy

Nanotechnology has emerged as an ideal approach for achieving the efficient chemo agent delivery. However, the potential toxicity and unclear internal metabolism of most nano-carriers was still a major obstacle for the clinical application. Herein, a novel “core‒shell” co-assembly carrier-free nanosystem was constructed based on natural sources of ursolic acid (UA) and polyphenol (EGCG) with the EpCAM-aptamer modification for hepatocellular carcinoma (HCC) synergistic treatment. As the nature products derived from food-plant, UA and EGCG had good anticancer activities and low toxicity. With the simple and “green” method, the nanodrugs had the advantages of good stability, pH-responsive and strong penetration of tumor tissues, which was expected to increase tumor cellular uptake, long circulation and effectively avoid the potential defects of traditional carriers. The nanocomplex exhibited the low cytotoxicity in the normal cells in vitro, good biosafety of organic tissues and efficient tumor accumulation in vivo. Importantly, UA combined with EGCG showed the immunotherapy by activating the innate immunity and acquired immunity resulting in significant synergistic therapeutic effect. The research could provide new ideas for the research and development of self-assembly delivery system in the future, and offer effective intervention strategies for clinical HCC treatment.

Recent advances in HER2-targeted delivery for cancer therapy

Human epidermal growth factor receptor 2 (HER2), a tyrosine kinase receptor with a molecular mass of 185kDa, is overexpressed in several cancers, such as breast, gastric, ovary, prostate, and lung. HER2 is a promising target in cancer therapy because of its crucial role in cell migration, proliferation, survival, angiogenesis, and metastasis through various intracellular signaling cascades. This receptor is an ideal target for the delivery of chemotherapeutic agents because of its accessibility to the extracellular domain. In this review, we highlight different HER2-targeting strategies and various approaches for HER2-targeted delivery systems to improve outcomes for cancer therapy.

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.

Self-assembled amphiphile-based nanoparticles for the inhibition of hepatocellular carcinoma metastasis via ICAM-1 mediated cell adhesion

Nanosized drug delivery systems have emerged to improve the therapeutic performance of anticancer drugs. Here, an amphiphile-based nanoparticle consisting of amphiphilic prodrug N-[3b-acetoxy-urs-12-en-28-oyl]-amino-2-methylpiperazine was developed (UP12 NPs) with uniform sizes (~100 nm), which possessed the advantages of small molecules and nanomedicine. The positively charged UP12 NPs significantly enhanced the cellular drug uptake on HepG2 cells than negatively charged UA NPs. Meanwhile, UP12 and these therapeutic amphiphile-based nanoparticles could induce cell apoptosis more efficiently than that of UA and UA NPs. Moreover, molecular docking demonstrated that the UP12 and intercellular adhesion molecule 1 (ICAM-1) could dock well. UP12 and UP12 NPs significantly decreased the mRNA expression of ICAM-1 and inhibited the migration and adhesion of liver cancer cells (HepG2 cells), which indicated that UP12 might be one of the potential ICAM-1 inhibitors. In vivo, UP12 NPs enhanced tumor accumulation, inhibited tumor lung metastasis and showed good biocompatibility. Overall, UP12 or UP12 NPs could be developed as prospective drugs for cancer metastasis therapy via ICAM-1 mediated cell adhesion. STATEMENT OF SIGNIFICANCE: In this study, we fabricated the therapeutic amphiphile-based nanoparticles by assembly of ursolic acid piperazine derivative N-[3b-acetoxy-urs-12-en-28-oyl]-amino-2-methylpiperazine (name as UP12 NPs) with low cytotoxicity. UP12 NPs exhibited spherical morphology and uniform sizes. Particularly, these therapeutic amphiphile-based nanoparticles significantly enhanced tumor accumulation and inhibited tumor lung metastases via intercellular adhesion molecule 1 (ICAM-1) mediated cell adhesion.

Biologicals to direct nanotherapeutics towards HER2-positive breast cancers

HER2-positive breast cancer, an aggressive cancer, is treated with combinations of conventional anticancer drugs viz., cytotoxic drugs, nibs, and mAbs. Major limitations associated with this therapy are patient non-compliance due to the adverse drug reactions and rapid development of resistance by the HER2-positive malignant cells. While the former is addressed by the nano-formulations of the anticancer-drugs to some extent, the latter is still at large. This is because the nanocarriers of the anticancer drugs, by and large, lack the target specificity and selectivity. Thus, nowadays, to overcome these problems, various safe and efficacious biological agents are being used to direct the nanotherapeutics towards the HER2-positive breast cancers. The present review describes the potentials of such biological agents.

Evolution from small molecule to nano-drug delivery systems: An emerging approach for cancer therapy of ursolic acid

Ursolic acid (UA), a natural pentacyclic triterpenoid, possesses widespread biological and pharmacological activities. However, drawbacks such as low bioavailability, poor targeting and rapid metabolism greatly hinder its further clinical application. Recently, with the development of nanotechnology, various UA nanosystems have emerged as promising strategies for effective cancer therapy. This article reviews various types of UA-based nano-delivery systems, primarily with emphasis placed on novel UA-based carrier-free nano-drugs, which are considered to be innovative methods for cancer therapy. Moreover, this review presents carrier-free nano-drugs that co-assembled of UA and photosensitizers that displayed synergistic antitumor performance. Finally, the article also describes the development and challenges of UA nanosystems for future research in this field. Overall, the information presented in this review will provide new insight into the rational utilization of nano-drugs in cancer therapy.

Nanoscale Self-Assembly for Therapeutic Delivery

Self-assembly is the process of association of individual units of a material into highly arranged/ordered structures/patterns. It imparts unique properties to both inorganic and organic structures, so generated, via non-covalent interactions. Currently, self-assembled nanomaterials are finding a wide variety of applications in the area of nanotechnology, imaging techniques, biosensors, biomedical sciences, etc., due to its simplicity, spontaneity, scalability, versatility, and inexpensiveness. Self-assembly of amphiphiles into nanostructures (micelles, vesicles, and hydrogels) happens due to various physical interactions. Recent advancements in the area of drug delivery have opened up newer avenues to develop novel drug delivery systems (DDSs) and self-assembled nanostructures have shown their tremendous potential to be used as facile and efficient materials for this purpose. The main objective of the projected review is to provide readers a concise and straightforward knowledge of basic concepts of supramolecular self-assembly process and how these highly functionalized and efficient nanomaterials can be useful in biomedical applications. Approaches for the self-assembly have been discussed for the fabrication of nanostructures. Advantages and limitations of these systems along with the parameters that are to be taken into consideration while designing a therapeutic delivery vehicle have also been outlined. In this review, various macro- and small-molecule-based systems have been elaborated. Besides, a section on DNA nanostructures as intelligent materials for future applications is also included.

Water-Soluble, Zwitterionic Poly-photosensitizers as Carrier-Free, Photosensitizer-Self-Delivery System for in Vivo Photodynamic Therapy

Polymeric nanoparticles (NPs) have been widely established to deliver most of the hydrophobic chemo-drugs or photosensitizers (PSs) for cancer therapy. However, this strategy is usually hindered by the relatively low drug loading capacity and the undesired toxicity as well as the immunogenicity caused by the nontherapeutic, polymeric carriers. The carrier-free, drug self-delivery systems, in which the chemo-drugs or their prodrugs themselves formed the NPs without the addition of nontherapeutic carriers, have been extensively developed to achieve a high drug loading capacity and low systemic toxicity. However, most of the driving forces to form the NPs were based on the strong hydrophobic interactions, which were the undesired forces for the porphyrin-based hydrophobic PSs due to the parasitic aggregation-caused quenching effect. Herein, the zwitterionic, water-soluble, and reactive oxygen species (ROS)-cleavable poly-photosensitizers (pPSs) were prepared by the polymerization method, which spontaneously introduced different charges associated with the "desired electrostatic effect" and reduced the "undesired aggregation" by separating the PS monomers using flexible and ROS-cleavable linkers. The obtained pPS could be self-assembled into the nanocomplexes based on the electrostatic effect with a high PS loading capacity, improved singlet oxygen generation ability, and efficient phototoxicity. Upon poly(ethylene glycol) (PEG) or hyaluronic acid (HA) coating on the surface, both pPS/PEG and pPS/HA complexes exhibited enhanced stability under physiological environments and excellent in vivo antitumor efficacy. Moreover, HA-coated complexes also exhibited active tumor targeting. Such a polymerization strategy comprehensively addressed the parasitic issues for the hydrophobic PS self-delivery system in the photodynamic therapy area.

Ursolic Acid in Cancer Treatment and Metastatic Chemoprevention: From Synthesized Derivatives to Nanoformulations in Preclinical Studies

BACKGROUND

Cancer metastasis has emerged as a major public health threat that causes majority of cancer fatalities. Traditional chemotherapeutics have been effective in the past but suffer from low therapeutic efficiency and harmful side-effects. Recently, it has been reported ursolic acid (UA), one of the naturally abundant pentacyclic triterpenes, possesses a wide range of biological activities including anti-inflammatory, anti-atherosclerotic, and anti-cancer properties. More importantly, UA has the features of low toxicity, liver protection and the potential of anti-cancer metastasis.

OBJECTIVE

This article aimed at reviewing the great potential of UA used as a candidate drug in the field of cancer therapy relating to suppression of tumor initiation, progression and metastasis.

METHODS

Selective searches were conducted in Pubmed, Google Scholar and Web of Science using the keywords and subheadings from database inception to December 2017. Systemic reviews are summarized here.

RESULTS

UA has exhibited chemopreventive and therapeutic effects of cancer mainly through inducing apoptosis, inhibiting cell proliferation, preventing tumor angiogenesis and metastatic. UA nanoformulations could enhance the solubility and bioavailability of UA as well as exhibit better inhibitory effect on tumor growth and metastasis.

CONCLUSION

The information presented in this article can provide useful references for further studies on making UA a promising anti-cancer drug, especially as a prophylactic metastatic agent for clinical applications.

Treating Tumors at Low Drug Doses Using an Aptamer-Peptide Synergistic Drug Conjugate

Combination chemotherapy must strike a difficult balance between safety and efficacy. Current regimens suffer from poor therapeutic impact because drugs are given at their maximum tolerated dose (MTD), which compounds the toxicity risk and exposes tumors to non-optimal drug ratios. A modular framework has been developed that selectively delivers drug combinations at synergistic ratios via tumor-targeting aptamers for effective low-dose treatment. A nucleolin-recognizing aptamer was coupled to peptide scaffolds laden with precise ratios of doxorubicin (DOX) and camptothecin (CPT). This construct had an extremely low IC₅₀ (31.9 nm) against MDA-MB-231 breast cancer cells in vitro, and exhibited in vivo efficacy at micro-dose injections (500 and 350 μg kg^-1  dose^-1 of DOX and CPT, respectively) that are 20-30-fold lower than their previously-reported MTDs. This approach represents a generalizable strategy for the safe and consistent delivery of combination drugs in oncology.

Gram-scale production of carrier-free fluorescent berberine microrods for selective liver cancer therapy

Berberine, a widely used isoquinoline alkaloid in traditional Chinese medicine, has been proved to be a potential candidate in liver cancer therapy. However, the low therapeutic dose in the tumor target which is due to the poor solubility and oral bioavailability has limited its clinical application. In this study, fluorescent self-carried Berberine microrods (Ber-MRs) were prepared in gram-scale through a facile and cheap antisolvent precipitation method. Ber-MRs exhibited good optical properties, pH-responsive drug release behavior and selective and safe antitumor performance in vitro and in vivo without obvious toxicity. These findings have demonstrated that Ber-MRs are promising for efficient and safe liver cancer therapy. © 2018 BioFactors, 44(5):496-502, 2018.

Carrier-free nanodrug by co-assembly of chemotherapeutic agent and photosensitizer for cancer imaging and chemo-photo combination therapy

Nanosized drug delivery systems (NDDS) with photothermal therapy (PTT) and photodynamic therapy (PDT) have been extensively exploited to improve the therapeutic performance and bio-safety of chemotherapeutic drugs in cancer. In this work, a carrier-free nanodrug was developed by co-assembly of the anti-cancer agent ursolic acid (UA), an asialoglycoprotein receptor (ASGPR), which can recognize the target molecule lactobionic acid (LA), and the near-infrared (NIR) probe dye indocyanine green (ICG) to form UA-LA-ICG NPs by a simple and green self-assembly approach. The UA-LA-ICG NPs had suitable stability, showed controlled release profile of UA drugs, and exhibited preferable temperature response (∼59.4 °C) under laser irradiation (808 nm, 1 W/cm2). Compared with free ICG, the UA-LA-ICG NPs significantly enhanced the intracellular ICG uptake. Upon irradiation of the NIR laser, co-assembled nanodrugs demonstrated great performance as a reactive oxygen species (ROS) producer and exhibited more anti-proliferative activities on ASGPR-overexpressing HepG2 cells than ASGPR low-expressing HeLa cells. Meanwhile, in vivo NIR fluorescence imaging exhibited that the co-assembled nanodrugs were specifically targeted to the tumor by the active targeting property of LA, and its circulation time was much longer than that of free ICG. In addition, UA-LA-ICG NPs + NIR irradiation treatment displayed enhanced inhibitory effect on tumor growth in H22 tumor-bearing mice. Overall, the co-assembly of chemotherapeutic agent and photosensitizer by the self-assembly approach might open an alternative avenue and give inspiration to fabricate new carrier-free nanodrugs for cancer imaging and chemo-photo combination therapy.

STATEMENT OF SIGNIFICANCE

The present study for the first time reported carrier-free nanoparticles (NPs) by co-assembly of a natural product ursolic acid (UA), an asialoglycoprotein receptor (ASGPR)-recognized sugar molecule lactobionic acid (LA), and the near-infrared dye indocyanine green (ICG) through a simple and green approach. The preparation process of nanodrugs is simple, rapid, effective, and labor-saving. The co-assembled nanodrugs were capable of stabilizing the ICG molecules and specifically targeting to the tumor, which could increase the tumor accumulation in cancer imaging and also enhance the efficacy of chemo-phototherapy.

A Small Molecule Nanodrug by Self-Assembly of Dual Anticancer Drugs and Photosensitizer for Synergistic near-Infrared Cancer Theranostics

Phototherapy including photodynamic therapy (PDT) and photothermal therapy (PTT) has attracted great attention. However, applications of some photosensitizers remain an obstacle by their poor photostability. To enhance the treatment efficiency of photosensitizers and tumor theranostic effect, herein, we reported a novel carrier-free, theranostic nanodrug by self-assembly of small molecule dual anticancer drugs and photosensitizer for tumor targeting. The developed carrier-free small molecule nanodrug delivery system was formed by hydrophobic ursolic acid, paclitaxel, and amphipathic indocyanine green (ICG) associated with electrostatic, π-π stacking, and hydrophobic interactions exhibiting water stability. The self-assembling of ICG on the dual anticancer nanodrug significantly enhanced water solubility of hydrophobic anticancer drugs and ICG photostability contributing to long-term near-infrared (NIR) fluorescence imaging and effective chemophototherapy of tumor. The in vivo NIR fluorescence imaging showed that the theranostic nanodrug could be targeted to the tumor site via a potential enhanced permeability and retention effect proving the efficient accumulation of nanoparticles in the tumor site. Dramatically, chemophototherapy of tumor-bearing mice in vivo almost completely suppressed tumor growth and no tumor recurrence was observed. Encouraged by its carrier-free, prominent imaging and effective therapy, the small molecule nanodrug via self-assembly will provide a promising strategy for synergistic cancer theranostics.