Dual-Drug Backboned Polyprodrug with a Predefined Drug Combination for Synergistic Chemotherapy

Mn-based Prussian blue analogues: Multifunctional nanozymes for hydrogen peroxide detection and photothermal therapy of tumors

Nanozymes have the advantages of simple synthesis, high stability, low cost and easy recycling, and can be applied in many fields including molecular detection, disease diagnosis and cancer therapy. However, most of the current nanozymes suffer from the defects of low catalytic activity and single function, which limits their sensing sensitivity and multifunctional applications. The development of highly active and multifunctional nanozymes is an important way to realize multidisciplinary applications. In this work, Mn-based Prussian blue analogues (Mn-PBA) and their derived double-shelled nanoboxes (DSNBs) are synthesized by co-precipitation method. The nanobox structure of DSNBs formed by etching Mn-PBA with tannic acid endows Mn-PBA DSNBs with better peroxidase-like activity than Mn-PBA. A colorimetric method for the rapid and sensitive determination of H2O2 is developed using Mn-PBA DSNBs-1.5 as a sensor with a detection limit as low as 0.62 μM. Moreover, Mn-PBA DSNBs-2 has excellent photothermal conversion ability, which can be applied to the photothermal therapy of tumors to inhibit the proliferation of tumor cells without damaging other tissues and organs. This study provides a new idea for the rational design of nanozymes and the expansion of their multi-functional applications in various fields.

Recent advances in mitochondria-targeting theranostic agents

For its vital role in maintaining cellular activity and survival, mitochondrion is highly involved in various diseases, and several strategies to target mitochondria have been developed for specific imaging and treatment. Among these approaches, theranostic may realize both diagnosis and therapy with one integrated material, benefiting the simplification of treatment process and candidate drug evaluation. A variety of mitochondria-targeting theranostic agents have been designed based on the differential structure and composition of mitochondria, which enable more precise localization within cellular mitochondria at disease sites, facilitating the unveiling of pathological information while concurrently performing therapeutic interventions. Here, progress of mitochondria-targeting theranostic materials reported in recent years along with background information on mitochondria-targeting and therapy have been briefly summarized, determining to deliver updated status and design ideas in this field to readers.

Polydopamine-Based Nanoparticles for Synergistic Chemotherapy of Prostate Cancer

Introduction

Immune regulatory small molecule JQ1 can block its downstream effector PD-L1 pathway and effectively reverse the PD-L1 upregulation induced by doxorubicin (DOX). So the synergistic administration of chemotherapeutic drug DOX and JQ1 is expected to increase the sensitivity of tumors to immune checkpoint therapy and jointly enhance the body's own immunity, thus effectively killing tumor cells. Therefore, a drug delivery system loaded with DOX and JQ1 was devised in this study.

Methods

Polydopamine nanoparticles (PDA NPs) were synthesized through spontaneous polymerization. Under appropriate pH conditions, DOX and JQ1 were loaded onto the surface of PDA NPs, and the release of DOX and JQ1 were measured using UV-Vis or high performance liquid chromatography (HPLC). The mechanism of fabricated nanocomplex in vitro was investigated by cell uptake experiment, cell viability assays, apoptosis assays, and Western blot analysis. Finally, the tumor-bearing mouse model was used to evaluate the tumor-inhibiting efficacy and the biosafety in vivo.

Results

JQ1 and DOX were successfully loaded onto PDA NPs. PDA-DOX/JQ1 NPs inhibited the growth of prostate cancer cells, reduced the expression of apoptosis related proteins and induced apoptosis in vitro. The in vivo biodistribution indicated that PDA-DOX/JQ1 NPs could accumulated at the tumor sites through the EPR effect. In tumor-bearing mice, JQ1 delivered with PDA-DOX/JQ1 NPs reduced PD-L1 expression at tumor sites, generating significant tumor suppression. Furthermore, PDA-DOX/JQ1 NPs could reduce the side effects, and produce good synergistic treatment effect in vivo.

Conclusion

We have successfully prepared a multifunctional platform for synergistic prostate cancer therapy.

Research progress of nano-delivery systems for the active ingredients from traditional Chinese medicine

INTRODUCTION

Traditional Chinese medicine (TCM) has been used for thousands of years in China, characterizing with novel pharmacological mechanisms, low toxicity, and limited side effects. However, the application of TCM active ingredients is often hindered by their physical and chemical properties, including poor solubility, low bioavailability, short half-life, toxic side effects within therapeutic doses, and instability in biological environments. Consequently, an increasing number of researchers are directing their attention towards the discovery of nano-delivery systems for TCM to overcome these clinical challenges.

OBJECTIVES

This review aims to provide the latest knowledge and results concerning the studies on the nano-delivery systems for the active ingredients from TCM.

MATERIALS AND METHODS

Recent literature relating to nano-delivery systems for the active ingredients from TCM is summarized to provide a fundamental understanding of how such systems can enhance the application of phytochemicals.

RESULTS

The nano-delivery systems of six types of TCM monomers are summarized and categorized based on the skeletal structure of the natural compounds. These categories include terpenoids, flavonoids, alkaloids, quinones, polyphenols, and polysaccharides. The paper analyzes the characteristics, types, materials used, and the efficacy achieved by TCM-nano systems. Additionally, the advantages and disadvantages of nano-drug delivery systems for TCM are summarized in this paper.

CONCLUSION

Nano-delivery systems represent a promising approach to overcoming clinical obstacles stemming from the physical and chemical properties of TCM active ingredients, thereby enhancing their clinical efficacy.

Application of dual chemotherapeutic drug delivery system based on metal-organic framework platform in enhancing tumor regression for breast cancer research

The nanomedicine system based on dual drug delivery systems (DDDs) can significantly enhance the efficacy of tumor treatment. Herein, a metal-organic framework, Zeolite imidazole salt frames 8 (ZIF-8), was successfully utilized as a carrier to load the dual chemotherapeutic drugs doxorubicin (DOX) and camptothecin (CPT), named DOX/CPT@ZIF-8 (denoted as DCZ), and their inhibitory effects on 4T1 breast cancer cells were evaluated. The study experimentally demonstrated the synergistic effects of the dual chemotherapeutic drugs within the ZIF-8 carrier and showed that the ZIF-8 nano-carrier loaded with the dual drugs exhibited stronger cytotoxicity and inhibitory effects on 4T1 breast cancer cells compared to single-drug treatment. The use of a ZIF-8-based dual chemotherapeutic drug carrier system highlighted its potential advantages in suppressing 4T1 breast cancer cells.

Preparation of PMMA-Based Temperature/pH Responsive Nanoparticles Encapsulating 5-Fluorouracil and Methotrexate In Situ by One-Pot Dispersion Photopolymerization

In order to achieve long-term and controllable release of anti-tumor drugs at specific sites, temperature/pH responsive nanoparticles encapsulating 5-fluorouracil and methotrexate in situ are prepared through dispersion photopolymerization under green LED irradiation. The physicochemical properties of nanoparticles are characterized by scanning electron microscopy, Fourier transform infrared, dynamic light scattering, thermogravimetric/differential scanning calorimetry, and X-ray diffraction. In vitro drug release at different temperatures and pH values is examined to ascertain the release pattern of two drugs, which can be well described by Korsmeyer-Peppas kinetic model. The cytotoxicity evaluation illustrates that the tumor cells could be more effectively killed by the drug-loaded nanoparticles, and the improved therapeutic effect is attributed to the controllable and sustainable drug release as well as the enhanced cellular uptake. The blood safety and good biocompatibility of nanoparticles are further confirmed by hemolysis assay, indicating the prepared nanoparticles are potential candidates for effective tumor treatment.

Mitoxantrone encapsulated photosensitizer nanomicelle as carrier-free theranostic nanomedicine for near-infrared fluorescence imaging-guided chemo-photodynamic combination therapy on cancer

Combination therapy exhibits higher efficacy than any single therapy, inspiring various nanocarrier-assisted multi-drug co-delivery systems for the combined treatment of cancer. However, most nanocarriers are inert and non-therapeutic and have potential side effects. Herein, an amphiphilic polymer composed of a hydrophobic photosensitizer and hydrophilic poly(ethylene glycol) was employed as the nanocarriers and photosensitizers to encapsulate the chemotherapeutic drug mitoxantrone for chemo-photodynamic combination therapy. The resulting nanodrug consisted solely of pharmacologically active ingredients, thus avoiding potential toxicity induced by inert excipients. This multifunctional nanoplatform demonstrated significantly superior treatment performance compared to monotherapy for colorectal cancer, both in vitro and in vivo, achieving near-infrared fluorescence imaging-mediated chemo-photodynamic combined eradication of malignancy.

A Polymeric Nanoparticle to Co-Deliver Mitochondria-Targeting Peptides and Pt(IV) Prodrug: Toward High Loading Efficiency and Combination Efficacy

Developing combination chemotherapy systems with high drug loading efficiency at predetermined drug ratios to achieve a synergistic effect is important for cancer therapy. Herein, a polymeric dual-drug nanoparticle composed of a Pt(IV) prodrug derived from oxaliplatin and a mitochondria-targeting cytotoxic peptide is constructed through emulsion interfacial polymerization, which processes high drug loading efficiency and high biocompatibility. The depolymerization of polymeric dual-drug nanoparticle and the activation of Pt prodrug can be effectively triggered by the acidic tumor environment extracellularly and the high levels of glutathione intracellularly in cancer cells, respectively. The utilization of mitochondria-targeting peptide can inhibit ATP-dependent processes including drug efflux and DNA damage repair. This leads to increased accumulation of Pt-drugs within cancer cells. Eventually, the polymeric dual-drug nanoparticle demonstrates appreciable antitumor effects on both cell line derived and patient derived xenograft lung cancer model. It is highly anticipated that the polymeric dual-or multi-drug systems can be applied for combination chemotherapy to achieve enhanced anticancer activity and reduced side effects.

GSH-activable heterotrimeric nano-prodrug for precise synergistic therapy of TNBC

Combination chemotherapy is an effective approach for triple-negative breast cancer (TNBC) therapy, especially when drugs are administered at specific optimal ratios. However, at present, strategies involving precise and controllable ratios based on effective loading and release of drugs are unavailable. Herein, we designed and synthesized a glutathione (GSH)--responsive heterotrimeric prodrug and formulated it with an amphiphilic polymer to obtain nanoparticles (DSSC2 NPs) for precise synergistic chemotherapy of TNBC. The heterotrimeric prodrug was prepared using docetaxel (DTX) and curcumin (CUR) at the optimal synergistic ratio of 1: 2. DTX and CUR were covalently conjugated by disulfide linkers. Compared with control NPs, DSSC2 NPs had quantitative/ratiometric drug loading, high drug co-loading capacity, better colloidal stability, and less premature drug leakage. After systemic administration, DSSC2 NPs selectively accumulated in tumor tissues and released the encapsulated drugs triggered by high levels of GSH in cancer cells. In vitro and in vivo experiments validated that DSSC2 NPs released DTX and CUR at the predefined ratio and had a highly synergistic therapeutic effect on tumor suppression in TNBC, which can be attributed to ratiometric drug delivery and synchronous drug activation. Altogether, the heterotrimeric prodrug delivery system developed in this study represents an effective and novel approach for combination chemotherapy.

Probing the Impact of Surface Functionalization Module on the Performance of Mitoxantrone Prodrug Nanoassemblies: Improving the Effectiveness and Safety

Prodrug nanoassemblies are emerging as a novel drug delivery system for chemotherapy, comprising four fundamental modules: a drug module, a modification module, a response module, and a surface functionalization module. Among these modules, surface functionalization is an essential process to enhance the biocompatibility and stability of the nanoassemblies. Here, we selected mitoxantrone (MTO) as the drug module and DSPE-PEG2K as surface functionalization module to develop MTO prodrug nanoassemblies. We systematically evaluated the effect of surface functionalization module ratios (10%, 20%, 40%, and 60% of prodrug, WDSPE-mPEG2000/Wprodrug) on the prodrug nanoassemblies. The results indicated that 40% NPs significantly improved the self-assembly stability and cellular uptake of prodrug nanoassemblies. Compared with MTO solution, 40% NPs showed better tumor specificity and pharmacokinetics, resulting in potent antitumor activity with a good safety profile. These findings highlighted the pivotal role of the surface functionalization module in regulating the performance of mitoxantrone prodrug nanoassemblies for cancer treatment.

Structural Determinants of Stimuli-Responsiveness in Amphiphilic Macromolecular Nano-assemblies

Stimuli-responsive nano-assemblies from amphiphilic macromolecules could undergo controlled structural transformations and generate diverse macroscopic phenomenon under stimuli. Due to the controllable responsiveness, they have been applied for broad material and biomedical applications, such as biologics delivery, sensing, imaging, and catalysis. Understanding the mechanisms of the assembly-disassembly processes and structural determinants behind the responsive properties is fundamentally important for designing the next generation of nano-assemblies with programmable responsiveness. In this review, we focus on structural determinants of assemblies from amphiphilic macromolecules and their macromolecular level alterations under stimuli, such as the disruption of hydrophilic-lipophilic balance (HLB), depolymerization, decrosslinking, and changes of molecular packing in assemblies, which eventually lead to a series of macroscopic phenomenon for practical purposes. Applications of stimuli-responsive nano-assemblies in delivery, sensing and imaging were also summarized based on their structural features. We expect this review could provide readers an overview of the structural considerations in the design and applications of nanoassemblies and incentivize more explorations in stimuli-responsive soft matters.

n-Tuples on Scaffold Diversity Inspired by Drug Hybridisation to Enhance Drugability: Application to Cytarabine

A mathematical concept, n-tuples are originally applied to medicinal chemistry, especially with the creation of scaffold diversity inspired by the hybridisation of different commercial drugs with cytarabine, a synthetic arabinonucleoside derived from two marine natural products, spongouridine and spongothymidine. The new methodology explores the virtual chemical-factorial combination of different commercial drugs (immunosuppressant, antibiotic, antiemetic, anti-inflammatory, and anticancer) with the anticancer drug cytarabine. Real chemical combinations were designed and synthesised for 8-duples, obtaining a small representative library of interesting organic molecules to be biologically tested as proof of concept. The synthesised library contains classical molecular properties regarding the Lipinski rules and/or beyond rules of five (bRo5) and is represented by the covalent combination of the anticancer drug cytarabine with ibuprofen, flurbiprofen, folic acid, sulfasalazine, ciprofloxacin, bortezomib, and methotrexate. The insertion of specific nomenclature could be implemented into artificial intelligence algorithms in order to enhance the efficiency of drug-hunting programs. The novel methodology has proven useful for the straightforward synthesis of most of the theoretically proposed duples and, in principle, could be extended to any other central drug.

Challenges and opportunities for improving the druggability of natural product: Why need drug delivery system?

Bioactive natural products (BNPs) are the marrow of medicinal plants, which are the secondary metabolites of organisms and have been the most famous drug discovery database. Bioactive natural products are famous for their enormous number and great safety in medical applications. However, BNPs are troubled by their poor druggability compared with synthesis drugs and are challenged as medicine (only a few BNPs are applied in clinical settings). In order to find a reasonable solution to improving the druggability of BNPs, this review summarizes their bioactive nature based on the enormous pharmacological research and tries to explain the reasons for the poor druggability of BNPs. And then focused on the boosting research on BNPs loaded drug delivery systems, this review further concludes the advantages of drug delivery systems on the druggability improvement of BNPs from the perspective of their bioactive nature, discusses why BNPs need drug delivery systems, and predicts the next direction.

Recent advances in Prussian blue-based photothermal therapy in cancer treatment

Malignant tumours are a serious threat to human health. Traditional chemotherapy has achieved breakthrough improvements but also has significant detrimental effects, such as the development of drug resistance, immunosuppression, and even systemic toxicity. Photothermal therapy (PTT) is an emerging cancer therapy. Under light irradiation, the phototherapeutic agent converts optical energy into thermal energy and induces the hyperthermic death of target cells. To date, numerous photothermal agents have been developed. Prussian blue (PB) nanoparticles are among the most promising photothermal agents due to their excellent physicochemical properties, including photoacoustic and magnetic resonance imaging properties, photothermal conversion performance, and enzyme-like activity. By the construction of suitably designed PB-based nanotherapeutics, enhanced photothermal performance, targeting ability, multimodal therapy, and imaging-guided cancer therapy can be effectively and feasibly achieved. In this review, the recent advances in PB-based photothermal combinatorial therapy and imaging-guided cancer therapy are comprehensively summarized. Finally, the potential obstacles of future research and clinical translation are discussed.

Charge-conversional click polyprodrug nanomedicine for targeted and synergistic cancer therapy

Polyprodrug nanomedicines hold great potential for combating tumors. However, the functionalization of polyprodrug nanomedicines to improve therapeutic efficacy is restricted by conventional polymerization methods. Herein, we fabricated a charge-conversional click polyprodrug nanomedicine system by metal-free azide-alkyne cycloaddition click polymerization (AACCP) for targeted and synergistic cancer therapy. Specifically, Pt(IV) prodrug-backboned diazide monomer, DMC prodrug-pendent diazide monomer, dialkyne-terminated PEG monomer and azide-modified folate were click polymerized to obtain the target polyprodrug (P1). P1 could self-assemble into nano-micelles (1-NM), where PEG was the hydrophilic shell with folate on the surface, Pt(IV) and DMC prodrugs as the hydrophobic core. Taking advantage of PEGylation and folate-mediated tumor cell targeting, 1-NM achieved prolonged blood circulation time and high tumor accumulation efficiency. Tumor acidic microenvironment-responsive cleavage and cascade activation of pendant DMC prodrug induced surface charge conversion of 1-NM from negative to positive, which promoted tumor penetration and cellular internalization of the remaining 1-NM. After internalization into tumor cells, the reduction-responsive activation of Pt(IV) prodrug to Pt(II) further showed synergetic effect with DMC for enhanced apoptosis. This first designed charge-conversional click polyprodrug nanomedicine exhibited targeted and synergistic efficacy to suppress tumor proliferation in living mice bearing human ovarian tumor model.

Hyaluronic Acid-based Supramolecular Nanomedicine with Optimized Ratio of Oxaliplatin/Chlorin e6 for Combined Chemotherapy and O2-Economized Photodynamic Therapy

Dual- or multi-modality combination therapy has become one of the most effective strategies to overcome drug resistance in cancer therapy, and the optimized ratio of the therapeutic agents working on the tumor greatly affects the therapeutic outcomes. However, the absence of a facile method to optimize the ratio of therapeutic agents in nanomedicine has, at least in part, impaired the clinical potential of combination therapy. Herein, a new cucurbit[7]uril (CB[7])-conjugated hyaluronic acid (HA) based nanomedicine was developed, in which both chlorin e6 (Ce6) and oxaliplatin (OX) were co-loaded non-covalently at an optimized ratio via facile host-guest complexation, for optimal, combined photodynamic therapy (PDT)/chemotherapy. To maximize the therapeutic efficacy, a mitochondrial respiration inhibitor, atovaquone (Ato), was also loaded into the nanomedicine to limit consumption of oxygen by the solid tumor, sparing oxygen for more efficient PDT. Additionally, HA on the surface of nanomedicine allowed targeted delivery to cancer cells with over-expressed CD44 receptors (such as CT26 cell lines). Thus, this supramolecular nanomedicine platform with an optimal ratio of photosensitizer and chemotherapeutic agent not only provides an important new tool for enhanced PDT/chemotherapy of solid tumors, but also offers a CB[7]-based host-guest complexation strategy to facilely optimize the ratio of therapeutic agents for multi-modality nanomedicine. STATEMENT OF SIGNIFICANCE: Chemotherapy remains the most common modality for cancer treatment in clinical practice. Combination therapy by co-delivery of two or more therapeutic agents has been recognized as one of the most effective strategies to improve therapeutic outcome of cancer treatment. However, the ratio of loaded drugs could not be facilely optimized, which may greatly affect the combination efficiency and overall therapeutic outcome. Herein, we developed a hyaluronic acid based supramolecular nanomedicine with facile method to optimize the ratio of two therapeutic agents for improved therapeutic outcome. This supramolecular nanomedicine not only provides an important new tool for enhanced photodynamic therapy/chemotherapy of solid tumors, but also offers insights in using macrocyclic molecule-based host-guest complexation to facilely optimize the ratio of therapeutic agents in multi-modality nanomedicine.

A novel manganese dioxide-based drug delivery strategy via in situ coating γ-polyglutamic acid/cisplatin for intelligent anticancer therapy

Cisplatin (CDDP) is one of the most frequently used chemotherapeutic drugs due to its broad-spectrum and potent antitumor activity. Unfortunately, inactivation due to glutathione (GSH) substances and insufficient cellular uptake of CDDP greatly hinder its clinical applications. Herein, manganese dioxide (MnO₂) was reported as an efficient glutathione (GSH) consumption material for promoting the accumulation and preventing premature leakage of CDDP in tumor cells. In this work, γ-polyglutamic acid/cisplatin (PGA/CDDP) conjugates and PGA/CDDP nanoparticles (NPs) were respectively constructed via the ligand exchange reaction and electrostatic interaction. Furthermore, PGA/CDDP NPs were in situ coated with MnO₂ (PGA/CDDP@MnO₂ NPs) through the redox reaction of the residual carboxyl group (-COOH) and potassium permanganate (KMnO₄). As a result, the PGA/CDDP@MnO₂ NPs achieved a satisfactory drug-loading efficiency (ca. 37.26%) and multi-responsive controlled drug release. Remarkably, the MnO₂ shells exhibited excellent performance for efficient glutathione (GSH) consumption and significantly enhanced the killing effect (ca. 2-3 times) in human lung cancer cells (A549) compared with pure CDDP. Moreover, it was observed that PGA/CDDP@MnO₂ NPs could also inhibit the migration and invasion of A549 cells. Overall, these remarkable performances of PGA/CDDP@MnO₂ NPs make MnO₂ promising for controlled drug release and intelligent anticancer therapy.

Poly(pro-curcumin) Materials Exhibit Dual Release Rates and Prolonged Antioxidant Activity as Thin Films and Self-Assembled Particles

Curcumin is a natural polyphenol that exhibits remarkable antioxidant and anti-inflammatory activities; however, its clinical application is limited in part by its physiological instability. Here, we report the synthesis of curcumin-derived polyesters that release curcumin upon hydrolytic degradation to improve curcumin stability and solubility in physiological conditions. Curcumin was incorporated in the polymer backbone by a one-pot condensation polymerization in the presence of sebacoyl chloride and polyethylene glycol (PEG, M_n = 1 kDa). The thermal and mechanical properties, surface wettability, self-assembly behavior, and drug-release kinetics all depend sensitively on the mole percentage of curcumin incorporated in these statistical copolymers. Curcumin release was triggered by the hydrolysis of phenolic esters on the polymer backbone, which was confirmed using a PEGylated curcumin model compound, which represented a putative repeating unit within the polymer. The release rate of curcumin was controlled by the hydrophilicity of the polymers. Burst release (2 days) and extended release (>8 weeks) can be achieved from the same polymer depending on curcumin content in the copolymer. The materials can quench free radicals for at least 8 weeks and protect primary neurons from oxidative stress in vitro. Further, these copolymer materials could be processed into both thin films and self-assembled particles, depending on the solvent-based casting conditions. Finally, we envision that these materials may have potential for neural tissue engineering application, where antioxidant release can mitigate oxidative stress and the inflammatory response following neural injury.

Fine-tuning the sequential drug release of nano-formulated mutual prodrugs dictates the combination effects

Nanoformulated mutual prodrugs able to release two drugs either in order or simultaneously which significantly affected the combination effects consistently in vitro and in vivo, and links the in vitro–in vivo optimization of therapeutic effects.

Synthesis of Carrier-Free Paclitaxel-Curcumin Nanoparticles: The Role of Curcuminoids

The systemic administration of paclitaxel (PTX)-based combinatorial therapies is significantly restricted due to the multidrug resistance. Curcumin (CUR) not only inhibits cancer-cell proliferation but also reverses the PTX resistance. However, achieving codelivery of these two drugs is a challenge due to their poor water solubility. Herein, we synthesized carrier-free PTX NPs by a facile nanoprecipitation method with the help of CUR and other curcuminoids present in turmeric extract. The prepared NPs demonstrated spherical morphologies with high conformational stability. Experimental studies showed that the presence of both bisdemethoxycurcumin and demethoxycurcumin is essential for the successful formation of spherical and monodisperse NPs. Computational studies revealed that the presence of the more sterically available curcuminoids BMC and DMC makes the self-assembly procedure more adaptable with a higher number of potential conformations that could give rise to more monodisperse PTX-CUR NPs. Compared with PTX alone, PTX-CUR NPs have shown comparable therapeutic efficiency in vitro and demonstrated a higher cellular internalization, highlighting their potential for in vivo applications. The successful formation of PTX-CUR NPs and the understanding of how multiple drugs behave at the molecular level also provide guidance for developing formulations for the synthesis of high-quality and effective carrier-free nanosystems for biomedical applications.

αvβ3 integrin-specific exosomes engineered with cyclopeptide for targeted delivery of triptolide against malignant melanoma

Background

Melanoma is the most malignant skin tumor and is difficult to cure with the alternative treatments of chemotherapy, biotherapy, and immunotherapy. Our previous study showed that triptolide (TP) exhibited powerful tumoricidal activity against melanoma. However, the clinical potential of TP is plagued by its poor aqueous solubility, short half-life, and biotoxicity. Therefore, developing an ideal vehicle to efficiently load TP and achieving targeted delivery to melanoma is a prospective approach for making full use of its antitumor efficacy.

Results

We applied exosome (Exo) derived from human umbilical cord mesenchymal stromal cells (hUCMSCs) and engineered them exogenously with a cyclic peptide, arginine-glycine-aspartate (cRGD), to encapsulate TP to establish a bionic-targeted drug delivery system (cRGD-Exo/TP), achieving synergism and toxicity reduction. The average size of cRGD-Exo/TP was 157.34 ± 6.21 nm, with a high drug loading of 10.76 ± 1.21%. The in vitro antitumor results showed that the designed Exo delivery platform could be effectively taken up by targeted cells and performed significantly in antiproliferation, anti-invasion, and proapoptotic activities in A375 cells via the caspase cascade and mitochondrial pathways and cell cycle alteration. Furthermore, the biodistribution and pharmacokinetics results demonstrated that cRGD-Exo/TP possessed superior tumor targetability and prolonged the half-life of TP. Notably, cRGD-Exo/TP significantly inhibited tumor growth and extended survival time with negligible systemic toxicity in tumor-bearing mice.

Conclusion

The results indicated that the functionalized Exo platform provides a promising strategy for targeted therapy of malignant melanoma.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01597-1.

Surface charge switchable nano-micelle for pH/redox-triggered and endosomal escape mediated co-delivery of doxorubicin and paclitaxel in treatment of lung adenocarcinoma

Recently, the stimulus-sensitive drug co-delivery system has gained increasing attentions in the clinic and exhibits improved efficiency rather than the mono-chemotherapy in anti-tumor therapy. Herein, the smart charge switchable nano-micelles (NMs) were fabricated for the endosomal escape mediated co-delivery of doxorubicin (DOX) and paclitaxel (PTX) in treatment of lung adenocarcinoma. The disulfide bonds were facilitated as the linker of the polymer backbone to achieve the redox-sensitive degradation by high intracellular GSH, and acid-liable DMMA was grafted onto DOX molecules for pH-triggered drug release under acidic tumoral microenvironment. Folic acid (FA) was utilized as targeting molecule for facilitating entry of the as prepared NMs into cancer cells. Remarkably, the as fabricated NMs exhibited surface charge-switch from negative to positive during transmitting from physiological pH to the tumor extracellular pH, which can improve the cellular internalization towards cancer cell. Subsequently, the "proton-sponge" effect mediated endosome escape of the NMs was facilitated in the acidic endo/lysosome environment. By the cell assay, the NMs possessed good biocompatibility, excellent cellular uptake, and improved inhibition rate against cancer cell. Moreover, the co-delivery of DOX/PTX exhibited synergistic and enhanced solid tumor inhibition efficiency comparing to mono-chemotherapy in A-549 tumor bearing mice model. Based on above experimental results, the as prepared drug co-delivery system showed promising biosafety and potentials for efficient lung adenocarcinoma treatment in clinic.

Degradable polyprodrugs: design and therapeutic efficiency

Prodrugs are developed to increase the therapeutic properties of drugs and reduce their side effects. Polyprodrugs emerged as highly efficient prodrugs produced by the polymerization of one or several drug monomers. Polyprodrugs can be gradually degraded to release therapeutic agents. The complete degradation of polyprodrugs is an important factor to guarantee the successful disposal of the drug delivery system from the body. The degradation of polyprodrugs and release rate of the drugs can be controlled by the type of covalent bonds linking the monomer drug units in the polymer structure. Therefore, various types of polyprodrugs have been developed based on polyesters, polyanhydrides, polycarbonates, polyurethanes, polyamides, polyketals, polymetallodrugs, polyphosphazenes, and polyimines. Furthermore, the presence of stimuli-responsive groups, such as redox-responsive linkages (disulfide, boronate ester, metal-complex, and oxalate), pH-responsive linkages (ester, imine, hydrazone, acetal, orthoester, P-O and P-N), light-responsive (metal-complex, o-nitrophenyl groups) and enzyme-responsive linkages (ester, peptides) allow for a selective degradation of the polymer backbone in targeted tumors. We envision that new strategies providing a more efficient synergistic therapy will be developed by combining polyprodrugs with gene delivery segments and targeting moieties.

Self-boosting stimulus activation of a polyprodrug with cascade amplification for enhanced antitumor efficacy

The use of polyprodrugs, which bind drugs to polymer chains through responsive linkers, is a potential technique for cancer therapy; however, a lack of endogenous triggering factors limits drug activation in tumor tissue. Herein, we rationally created a reactive oxygen species (ROS)-sensitive polyprodrug (TS_CA/DOX) with cascade amplification of triggering agents and drug activation by incorporating both an ROS signal amplifier (TA_CA) and a drug activation amplifier (SIP_DOX) into a delivery system. Endogenous ROS as a triggering mechanism kicked off the initial circulation phase to increase intracellular ROS signals. Subsequently, the enhanced ROS initiated the second degradation step, allowing the polyprodrug SIP_DOX to fracture spontaneously in a domino-like fashion, resulting in self-accelerated drug activation in tumor tissue. Therefore, the polyprodrug created in this study with cascade amplification of drug activation holds great promise for effective cancer treatment.

Construction of pH-sensitive targeted micelle system co-delivery with curcumin and dasatinib and evaluation of anti-liver cancer

Nanomedicine delivery systems can achieve precise drug delivery and reduce toxic side effects compared with traditional drug delivery methods, but further development is still needed to eliminate obstacles such as multiple drug co-delivery, uncontrolled drug-release, and drug-resistance. Herein, we designed a dual drug-loaded nanosystem (THCD-NPs) that selectively transports and targets tumor cells for the treatment of liver cancer. In this drug delivery system, hyaluronic acid (HA)-conjugated curcumin (Cur) and d-α-tocopherol acid polyethylene glycolsuccinate (TPGS) were used as selective drug-carrying vehicles to deliver dasatinib (DAS) to cancer cells for combined administration. The mean size of the nanoparticles was approximately 66.14 ± 4.02 nm with good in vitro stability. The nanoparticles were pH sensitive and could accelerate drug release at low pH conditions. In vitro experiments showed that THCD-NPs were significantly cytotoxic to HepG2 cells and could be effectively taken up by these cells. Detailed investigations also demonstrated its pro-apoptotic activity. In vivo NIR fluorescence imaging showed that the nanoparticles could accumulate efficiently at the tumor site. Meanwhile, in vivo experiments showed that THCD-NPs significantly inhibited tumor growth and reduced the toxic side effects of free drugs in a mouse solid tumor model. In short, the nanoparticles we prepared provide a new idea for the treatment of liver cancer.

Polyprodrug Nanomedicines: An Emerging Paradigm for Cancer Therapy

Nanomedicines have the potential to provide advanced therapeutic strategies in combating tumors. Polymer-prodrug-based nanomedicines are particularly attractive in cancer therapies owing to the maximum drug loading, prolonged blood circulation, and reduced premature leakage and side effects in comparison with conventional nanomaterials. However, the difficulty in precisely tuning the composition and drug loading of polymer-drug conjugates leads to batch-to-batch variations of the prodrugs, thus significantly restricting their clinical translation. Polyprodrug nanomedicines inherit the numerous intrinsic advantages of polymer-drug conjugates and exhibit well-controlled composition and drug loading via direct polymerization of therapeutic monomers, representing a promising nanomedicine for clinical tumor therapies. In this review, recent advances in the development of polyprodrug nanomedicines are summarized for tumor elimination. Various types of polyprodrug nanomedicines and the corresponding properties are first summarized. The unique advantages of polyprodrug nanomedicines and their key roles in various tumor therapies are further highlighted. Finally, current challenges and the perspectives on future research of polyprodrug nanomedicines are discussed.

Responsive polyprodrug for anticancer nanocarriers

Nanocarriers responsive to glutathione (GSH), a molecule overexpressed in cancer cells, are extensively investigated for the delivery of Pt-based chemotherapeutics for cancer treatment.

Poly(disulfide)s: From Synthesis to Drug Delivery

Bioresponsive polymers have been widely used in drug delivery because of their degradability. For example, poly(disulfide)s with repeating disulfide bonds in the main chain have attracted considerable research attention. The characteristics of the disulfide bonds, including their dynamic and reversible properties and their responsiveness to stimuli such as reductants, light, heat, and mechanical force, make them ideal platforms for on-demand drug delivery. This review introduces the synthesis methods and applications of poly(disulfide)s. Furthermore, the synthesis methods of poly(disulfide)s are classified on the basis of the monomers used: oxidative step-growth polymerization with dithiols, ring-opening polymerization with cyclic disulfides, and polymerization with linear disulfides. In addition, recent advances in poly(disulfide)s for the delivery of small-molecule or biomacromolecular drugs are discussed. Quantum-dot-loaded poly(disulfide) delivery systems for imaging are also included. This review provides an overview of the various design strategies employed in the construction of poly(disulfide) platforms to inspire new applications in the field of drug delivery.

PEGylated Poly-HDACi: A Designer Polyprodrug from Optimized Drug Units

We designed, synthesized, and characterized a tri-block copolymer. Its hydrophobic part, a chain of histone deacetylase inhibitor (HDACi) prodrug, was symmetrically flanked by two identical PEG blocks, whereas the built-in HDACi was a linear molecule, terminated with a thiol at one end, and a hydroxyl group at the other. Such a feature facilitated end-to-end linkage of prodrugs through alternatively aligned disulfides and carbonates. The disulfides served dual roles: redox sensors of smart nanomedicine, and warheads of masked HDACi drugs. This approach, carefully designed to benefit both control-release and efficacy, is conceptually novel for optimizing drug units in nanomedicine. Micelles from this designer polyprodrug released only PEG, CO₂ and HDACi, and synergized with DOX against HCT116 cells, demonstrating its widespread potential in combination therapy. Our work highlights, for the first time, the unique advantage of thiol-based drug molecules in nanomedicine design.

Self-Remedied Nanomedicine for Surmounting the Achilles' Heel of Photodynamic Tumor Therapy

Oxygen-dependent photodynamic therapy (PDT) could exacerbate tumor hypoxia to induce the upregulation of hypoxia-inducible factor-1α (HIF-1α), which would promote tumor growth and metastasis. In this paper, a self-remedied nanomedicine is developed based on a photosensitizer and a HIF-1α inhibitor to surmount the Achilles' heel of PDT for enhanced antitumor efficacy. Specifically, the nanomedicine (designated as CYC-1) is prepared by the self-assembly of chlorine e6 (Ce6) and 3-(5'-hydroxy-methyl-2'-furyl)-1-benzylindazole (YC-1) through π-π stacking and hydrophobic interactions. Of special note, carrier-free CYC-1 holds an extremely high drug loading rate and avoids excipient-triggered adverse reactions. Intravenously administered CYC-1 prefers to accumulate in the tumor tissue for effective cellular uptake. More importantly, it is verified that CYC-1 is capable of inhibiting the HIF-1α activity, thereby improving its PDT efficacy on tumor suppression. Besides, CYC-1 has the overwhelming superiority in restraining tumor proliferation over the combined administration of Ce6 and YC-1, which highlights the advantage of this self-remedied strategy in drug delivery and tumor therapy. This study sheds light on the development of self-delivery nanomedicine for efficient PDT against malignancies.

A modular ROS-responsive platform co-delivered by 10-hydroxycamptothecin and dexamethasone for cancer treatment

Traditional and single treatment strategies are difficult to achieve good results due to tumor resistance and complex mechanisms. Combination therapy through co-delivery systems is one of the methods to improve the effectiveness of cancer treatment. The polyprodrug platform has inherent advantages such as high drug loading and strong stability. Herein, a new reactive oxygen species (ROS)-responsive micelle composed of poly 10-hydroxycamptothecin (pHCPT) and PEG is reported, which loaded dexamethasone (DEX) as synergistic drugs. The micelles collapse in the complex microenvironment of tumor cells to release DEX. The first released DEX can increase the ROS level of tumor cells, thereby facilitating the cleavage of thioketal bonds to release intact HCPT molecules. Meanwhile, DEX can normalize tumor blood vessels, reduce adverse reactions, and further improve the efficacy of HCPT. This co-delivery system shows an ideal tumor suppressive effect in vivo and in vitro. Designing drugs into a modular multi-drug platform and selecting appropriate synergistic drugs according to the treatment plan provides a convenient strategy for future clinical treatment.

Time-programmed activation of dual polyprodrugs for synergistic cascade oxidation-chemotherapy

Combination therapy using multiple drugs with time-programmed administration is promising for enhanced cancer treatment. However, it is still challenging to achieve time-programmed drug release from a single nanocarrier. Here, dual polyprodrugs of hemicyanine dye (CyNH₂) and doxorubicin (DOX) are developed to achieve time-programmed prodrug activation for synergistic cascade oxidation therapy and chemotherapy. The polyprodrug NP_DOX/Cy, composed of CyNH₂, is modified with a glutathione (GSH)-responsive disulfate group, while DOX is modified with a reactive oxygen species (ROS)-response thioketal (TK) group. Upon uptake by cancer cells overexpressing GSH, CyNH₂ can be activated quickly and accumulate in the mitochondria to induce mitochondrial damage and ROS upregulation, thus achieving subsequent burst activation of DOX through the ROS-triggered cleavage of the TK linker. The early activation of CyNH₂ makes the cancer cells more sensitive to subsequent DOX treatment for a synergistic effect of from oxidation therapy and chemotherapy. Therefore, the polyprodrug with time-programmed drug activation developed in this work provides a promising strategy for synergistic cancer therapy.

Nanoparticulation of Prodrug into Medicines for Cancer Therapy

This article provides a broad spectrum about the nanoprodrug fabrication advances co-driven by prodrug and nanotechnology development to potentiate cancer treatment. The nanoprodrug inherits the features of both prodrug concept and nanomedicine know-how, attempts to solve underexploited challenge in cancer treatment cooperatively. Prodrugs can release bioactive drugs on-demand at specific sites to reduce systemic toxicity, this is done by using the special properties of the tumor microenvironment, such as pH value, glutathione concentration, and specific overexpressed enzymes; or by using exogenous stimulation, such as light, heat, and ultrasound. The nanotechnology, manipulating the matter within nanoscale, has high relevance to certain biological conditions, and has been widely utilized in cancer therapy. Together, the marriage of prodrug strategy which shield the side effects of parent drug and nanotechnology with pinpoint delivery capability has conceived highly camouflaged Trojan horse to maneuver cancerous threats.