NO-releasing polypeptide nanocomposites reverse cancer multidrug resistance via triple therapies

Polydopamine modified by pillar[5]arene in situ for targeted chemo-photothermal cancer therapy

A pillar[5]arene-modified polydopamine (PDA-P[5]OH) displaying pH/NIR dual-responsive properties was constructed successfully in situ for targeted chemo-photothermal cancer therapy.

Current trends in gas-synergized phototherapy for improved antitumor theranostics

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered an elegant solution to eradicate tumors due to its minimal invasiveness and low systemic toxicity. Nevertheless, it is still challenging for phototherapy to achieve ideal outcomes and clinical translation due to its inherent drawbacks. Owing to the unique biological functions, diverse gases have attracted growing attention in combining with phototherapy to achieve super-additive therapeutic effects. Specifically, gases such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have been proven to kill tumor cells by inducing mitochondrial damage in synergy with phototherapy. Additionally, several gases not only enhance the thermal damage in PTT and the reactive oxygen species (ROS) production in PDT but also improve the tumor accumulation of photoactive agents. The inflammatory responses triggered by hyperthermia in PTT are also suppressed by the combination of gases. Herein, we comprehensively review the latest studies on gas-synergized phototherapy for cancer therapy, including (1) synergistic mechanisms of combining gases with phototherapy; (2) design of nanoplatforms for gas-synergized phototherapy; (3) multimodal therapy based on gas-synergized phototherapy; (4) imaging-guided gas-synergized phototherapy. Finally, the current challenges and future opportunities of gas-synergized phototherapy for tumor treatment are discussed. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literature. (1) Strategies to design nanoplatforms for gas-synergized anti-tumor phototherapy have been summarized for the first time. Meanwhile, the integration of various imaging technologies and therapy modalities which endow these nanoplatforms with advanced theranostic capabilities has been summarized. (2) The mechanisms by which gases synergize with phototherapy to eradicate tumors are innovatively and comprehensively summarized. 2. The scientific impact and interest. This review elaborates current trends in gas-synergized anti-tumor phototherapy, with special emphases on synergistic anti-tumor mechanisms and rational design of therapeutic nanoplatforms to achieve this synergistic therapy. It aims to provide valuable guidance for researchers in this field.

Multimodal Nanoplatform with ROS Amplification to Overcome Multidrug Resistance in Prostate Cancer via Targeting P-Glycoprotein and Ferroptosis

Chemotherapy remains the most essential treatment for prostate cancer, but multidrug resistance (MDR) contributes to chemotherapy failure and tumor-related deaths. The overexpression of P-glycoprotein (P-gp) is one of the main mechanisms behind MDR. Here, this work reports a multimodal nanoplatform with a reactive oxygen species (ROS) cascade for gas therapy/ferroptosis/chemotherapy in reversing MDR. The nanoplatform disassembles when responding to intracellular ROS and exerts three main functions: First, nitric oxide (NO) targeted delivery can reverse MDR by downregulating P-gp expression and inhibiting mitochondrial function. Second, ferrocene-induced ferroptosis breaks the redox balance in the tumor intracellular microenvironment and synergistically acts against the tumor. Third, the release of paclitaxel (PTX) is precisely controlled in situ in the tumor for chemotherapy that avoids damage to normal tissues. Excitingly, this multimodal nanoplatform is a promising weapon for reversing MDR and may provide a pioneering paradigm for synergetic cancer therapy.

Emissive Nanoparticles from Co-assembly of Metallatetragon and Amphiphilic Tetraphenylethylene for Cancer Theranostics

Platinum(II)-based metallacycles/cages have obtained tremendous attention due to their fascinating topology and wide range of applications, such as fluorescent materials, cell imaging, and tumor treatment. In this work, a metallatetragon (1) was constructed from 4-(4-(1,2,2-triphenylvinyl)phenyl)pyridine (2) and 90° cis-Pt(II) (Pt) in acetone through the strategy called "coordination driven self-assembly". Interestingly, through co-assembly of 1 and poly(ethylene glycol)-modified tetraphenylethylene (TPE-PEG22), fluorescent nanotheranostics, which could generate singlet oxygen (1O2) under the NIR irradiation and release Pt drugs under a low-pH microenvironment, were prepared successfully. The obtained theranostics could realize living cell imaging and synergistic chemo-photodynamic therapy in vitro and in vivo.

Strategies to overcome cancer multidrug resistance (MDR) through targeting P-glycoprotein (ABCB1): An updated review

The emergence of multidrug resistance (MDR) in malignant tumors is one of the leading threats encountered currently in many chemotherapeutic agents. The overexpression of the ATP-binding cassette (ABC) transporters is involved in MDR. P-glycoprotein (P-gp)/ABCB1 is a member of the ABC transporter family that significantly increases the efflux of various anticancer drugs from tumor cells. Therefore, targeting P-gp with small molecule inhibitors is an effective therapeutic strategy to overcome MDR. Over the past four decades, diverse compounds with P-gp inhibitory activity have been identified to sensitize drug-resistant cells, but none of them has been proven clinically useful to date. Research efforts continue to discover an effective approach for circumventing MDR. This review has provided an overview of the most recent advances (last three years) in various strategies for circumventing MDR mediated by P-gp. It may be helpful for the scientists working in the field of drug discovery to further synthesize and discover new chemical entities/therapeutic modalities with less toxicity and more efficacies to overcome MDR in cancer chemotherapy.

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H2 O2 , GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.

A multi-functional nano-system combining PI3K-110α/β inhibitor overcomes P-glycoprotein mediated MDR and improves anti-cancer efficiency

P-glycoprotein (P-gp/ABCB1)-mediated multidrug resistance (MDR) in cancers severely limit chemotherapeutic efficacy. We recently reported that phosphatidylinositol-3-kinase (PI3K) 110α and 110β subunits can be novel targets for reversal of P-gp mediated MDR in cancers, and BAY-1082439 as an inhibitor specific for PI3K 110α and 110β subunits could reverse P-gp-mediated MDR by downregulating P-gp expression in cancer cells. However, BAY-1082439 has very low solubility, short half-life and high in-vivo clearance rate. Till now, nano-system with the functions to target PI3K P110α and P110β and reverse P-gp mediated MDR in cancers has not been reported. In our study, a tumor targeting drug delivery nano-system PBDF was established, which comprised doxorubicin (DOX) and BAY-1082439 respectively encapsulated by biodegradable PLGA-SH nanoparticles (NPs) that were grafted to gold nanorods (Au NRs) modified with FA-PEG-SH, to enhance the efficacy to reverse P-gp mediated MDR and to target tumor cells, further, to enhance the efficiency to inhibit MDR tumors overexpressing P-gp. In-vitro experiments indicated that PBDF NPs greatly enhanced uptake of DOX, improved the activity to reverse MDR, inhibited the cell proliferation, and induced S-phase arrest and apoptosis in KB-C2 cells, as compared with free DOX combining free BAY-1082439. In-vivo experiments further demonstrated that PBDF NPs improved the anti-tumor ability of DOX and inhibited development of KB-C2 tumors. Notably, the metastasis of KB-C2 cells in livers and lungs of nude mice were inhibited by treatment with PBDF NPs, which showed no obvious in-vitro or in-vivo toxicity.

H2O2 Self-Supplying and GSH-Depleting Nanocatalyst for Copper Metabolism-Based Synergistic Chemodynamic Therapy and Chemotherapy

Chemodynamic therapy (CDT) that involves the use of Fenton catalysts to convert endogenous hydrogen peroxide (H₂O₂) to hydroxyl radicals (·OH) constitutes a promising strategy for cancer therapy; however, insufficient endogenous H₂O₂ and glutathione (GSH) overexpression render its efficiency unsatisfactory. Herein, we present an intelligent nanocatalyst that comprises copper peroxide nanodots and DOX-loaded mesoporous silica nanoparticles (MSNs) (DOX@MSN@CuO₂) and can self-supply exogenous H₂O₂ and respond to specific tumor microenvironments (TME). Following endocytosis into tumor cells, DOX@MSN@CuO₂ initially decomposes into Cu²⁺ and exogenous H₂O₂ in the weakly acidic TME. Subsequently, Cu²⁺ reacts with high GSH concentrations, thereby inducing GSH depletion and reducing Cu²⁺ to Cu⁺ Next, the generated Cu⁺ undergoes Fenton-like reactions with exogenous H₂O₂ to accelerate toxic ·OH production, which exhibits a rapid reaction rate and is responsible for tumor cell apoptosis, thereby enhancing CDT. Furthermore, the successful delivery of DOX from the MSNs achieves chemotherapy and CDT integration. Thus, this excellent strategy can resolve the problem of insufficient CDT efficacy due to limited H₂O₂ and GSH overexpression. Integrating H₂O₂ self-supply and GSH deletion enhances CDT, and DOX-induced chemotherapy endows DOX@MSN@CuO₂ with effective tumor growth-inhibiting properties alongside minimal side effects in vivo.

A hyaluronic acid modified cuprous metal-organic complex for reversing multidrug resistance via redox dyshomeostasis

Multidrug resistance (MDR) which is often related to the overexpression of P-glycoprotein (P-gp) in drug-resistant cancer cells has been a major problem faced by current cancer chemotherapy. Reversing P-gp-related MDR by disrupting tumor redox homeostasis that regulates the expression of P-gp is a promising strategy. In this work, a hyaluronic acid (HA) modified nanoscale cuprous metal-organic complex (HA-CuTT) was developed to reverse P-gp-related MDR via two-way regulated redox dyshomeostasis, which was achieved by both Cu⁺-catalyzed generation of •OH and disulfide bonds-mediated depletion of glutathione (GSH). In vitro studies reveal that the DOX-loaded complex (HA-CuTT@DOX) has excellent targeting ability to HepG2-ADR cells due to the modification of HA and effectively induces redox dyshomeostasis in HepG2-ADR cells. Moreover, HA-CuTT@DOX can cause mitochondrial damage, decrease ATP level, and downregulate the P-gp expression, thereby leading to the reversal of MDR and the increased drug accumulation in HepG2-ADR cells. Importantly, in vivo experimental results show that it can achieve effective inhibition (89.6 %) of tumor growth in nude mice bearing HepG2-ADR cells. This is the first work to reverse P-gp-related MDR via two-way regulated redox dyshomeostasis based on a HA modified nanoscale cuprous metal-organic complex, providing a new therapeutic paradigm for effective treatment of MDR-related cancer.

Bio-Inspired Drug Delivery Systems: From Synthetic Polypeptide Vesicles to Outer Membrane Vesicles

Nanomedicine is a broad field that focuses on the development of nanocarriers to deliver specific drugs to targeted sites. A synthetic polypeptide is a kind of biomaterial composed of repeating amino acid units that are linked by peptide bonds. The multiplied amphiphilicity segment of the polypeptide could assemble to form polypeptide vesicles (PVs) under suitable conditions. Different from polypeptide vesicles, outer membrane vesicles (OMVs) are spherical buds of the outer membrane filled with periplasmic content, which commonly originate from Gram-negative bacteria. Owing to their biodegradability and excellent biocompatibility, both PVs and OMVs have been utilized as carriers in delivering drugs. In this review, we discuss the recent drug delivery research based on PVs and OMVs. These related topics are presented: (1) a brief introduction to the production methods for PVs and OMVs; (2) a thorough explanation of PV- and OMV-related applications in drug delivery including the vesicle design and biological assessment; (3) finally, we conclude with a discussion on perspectives and future challenges related to the drug delivery systems of PVs and OMVs.

Nitric Oxide and Tumors: From Small-Molecule Donor to Combination Therapy

As an important endogenous signaling molecule, nitric oxide (NO) is involved in various physiological and pathological activities in living organisms. It is proved that NO plays a critical role in tumor therapy, while the extremely short half-life and nonspecific distribution of NO greatly limit its further clinical applications. Thus, the past few decades have witnessed the progress made in conquering these shortcomings, including developing innovative NO donors, especially smart and multimodal nanoplatforms. These platforms can precisely control the spatiotemporal distribution of therapeutic agents in the organism, which make big differences in tumor treatment. Here current NO therapeutic mechanisms for cancer, NO donors from small molecules to smart-responsive nanodrug delivery platforms, and NO-based combination therapy are comprehensively reviewed, emphasizing outstanding breakthroughs in these fields and hoping to bring new insights into NO-based tumor treatments.

Subcellular-Targeted Near-Infrared-Responsive Nanomedicine with Synergistic Chemo-photothermal Therapy against Multidrug Resistant Cancer

Multidrug resistance (MDR) is a major obstacle to effective cancer treatment. Therefore, developing effective approaches for overcoming the limitation of MDR in cancer therapy is very essential. Chemotherapy combined with photothermal therapy (PTT) is a potential therapeutic option against MDR. Herein, we developed a subcellular-targeted near-infrared (NIR)-responsive nanomedicine (Fe₃O₄@PDA-TPP/S₂-PEG-hyd-DOX, abbreviated as Fe₃O₄-ATSPD) as a new photothermal agent with improved photothermal stability and efficiency. This system demonstrates high stability in blood circulation and can be accumulated at the tumor site by magnetic targeting enhanced permeability and retention effect (EPR). Near-infrared (NIR) irradiation at the tumor site generates a photothermal effect from the photosensitizer Fe₃O₄@PDA, leading to a dramatic decrease in mitochondrial membrane potential. Simultaneously, the conjugated drugs released under low pH condition in endosomes or lysosomes cause nucleus DNA damage and cell apoptosis. This subcellular-targeted NIR-responsive nanomedicine with efficient integration of diagnosis and therapy could significantly enhance MDR cancer treatment by combination of chemotherapy and PTT.

Recent progress in nitric oxide-generating nanomedicine for cancer therapy

Nitric oxide (NO) is an endogenous, multipotent biological signaling molecule that participates in several physiological processes. Recently, exogenous supplementation of tumor tissues with NO has emerged as a potential anticancer therapy. In particular, it induces synergistic effects with other conventional therapies (such as chemo-, radio-, and photodynamic therapies) by regulating the activity of P-glycoprotein, acting as a vascular relaxant to relieve tumor hypoxia, and participating in the metabolism of reactive oxygen species. However, NO is highly reactive, and its half-life is relatively short after generation. Meanwhile, NO-induced anticancer activity is dose-dependent. Therefore, the targeted delivery of NO to the tumor is required for better therapeutic effects. In the past decade, NO-generating nanomedicines (NONs), which enable sustained and specific NO release in tumor tissues, have been developed for enhanced cancer therapy. This review describes the recent efforts and preclinical achievements in the development of NON-based cancer therapies. The chemical structures employed in the fabrication of NONs are summarized, and the strategies involved in NON-based cancer therapies are elaborated.

Recent advances in diverse nanosystems for nitric oxide delivery in cancer therapy

Gas therapy has been proven to be a promising and advantageous treatment option for cancers. Studies have shown that nitric oxide (NO) is one of the smallest structurally significant gas molecules with great potential to suppress cancer. However, there is controversy and concern about its use as it exhibits the opposite physiological effects based on its levels in the tumor. Therefore, the anti-cancer mechanism of NO is the key to cancer treatment, and rationally designed NO delivery systems are crucial to the success of NO biomedical applications. This review summarizes the endogenous production of NO, its physiological mechanisms of action, the application of NO in cancer treatment, and nano-delivery systems for delivering NO donors. Moreover, it briefly reviews challenges in delivering NO from different nanoparticles and the issues associated with its combination treatment strategies. The advantages and challenges of various NO delivery platforms are recapitulated for possible transformation into clinical applications.

Enhanced photo-hypoxia-activated combination therapy traced by AIE photosensitizer and targeted by hyaluronic acid: Disulphide bond interference of detoxification barrier

The treatment efficacy of anticancer drugs in complex physiological environments is still restricted by multi-drug resistance. To overcome this issue, a nanodrug system of HA-SS@CuS@ZIF-8@TPZ&TBMACN (HSCZTT) that breaks through the detoxification barrier for tirapazamine (TPZ) delivery was developed in this manuscript. In addition to the photothermal effect aroused by CuS in HSCZTT, which can damage tumour cells, TBMACN with photostable fluorescence in the aggregate state can also generate sufficient reactive oxygen species (ROS) to destroy tumour cells. The continuous consumption of oxygen in PDT aggravates the hypoxic environment of tumours, which further activates the TPZ released in the acidic microenvironment of the tumour to achieve apoptosis of the tumour cells. The HSCZTT can not only target the CD44 receptor overexpressed on the surface of the cancer cell, but can also effectively consume a large amount of glutathione (GSH) through the disulphide bond-modified hyaluronic acid, which serves as a targeted disulphide bond, interfering with the detoxification barrier. Our finding presents a rational strategy to overcome multidrug resistance for the improved efficacy of anticancer drugs by the targeting of Hyaluronic acid (HA), release of the drug by the acid response of ZIF-8, breakthrough of the detoxification barrier, precise positioning of the drug release and combined treatment with phototherapy and hypoxia-activated chemotherapy.

Nitric oxide-containing supramolecular polypeptide nanomedicine based on [2]biphenyl-extended-pillar[6]arenes for drug resistance reversal

A kind of supramolecular polypeptide nanomedicine (BPC/DOX-ICG) was constructed with an anionic water-soluble [2]biphenyl-extended-pillar[6]arene (AWBpP6), and pyridinium-terminal- and S-nitrosothiol (SNO)-modified polypeptide (PPNC) via host-guest interactions to co-deliver doxorubicin (DOX) and indocyanine green (ICG) for drug resistance reversal. Upon near-infrared (NIR) irradiation, the NO generation could down-regulate the P-glycoprotein (P-gp) expression level to reverse multidrug resistance (MDR). Subsequently, the resulting reverse MDR could sensitize the free DOX and assist photothermal therapy (PTT) to enhance the tumoricidal potential. This supramolecular polypeptide nanomedicine provides an effective strategy for the multimodal synergistic therapies of photothermal therapy, NO generation therapy, and chemotherapy (i.e., PTT-NO-CT) to overcome MDR.

Tumor microenvironment responsive polypeptide-based supramolecular nanoprodrugs for combination therapy

Tumor microenvironment responsive nanomedicine has drawn considerable attention for combination therapy, but still remains a significant challenge for less side effects and enhanced anti-tumor efficiency. Herein, we develop a pH/ROS dual-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) by using pillar[5]arene-based host-guest strategy for combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT). The PFW-DOX/GOD consists of a pH-responsive ferrocene/pillar[5]arene-containing polypeptide, a ROS-responsive polyprodrug, and encapsulated glucose oxidase (GOD). Upon into intracellular acidic environment, PFW-DOX/GOD exhibits rapid pH-triggered disassembly behavior. Simultaneously, the released GOD can catalyze intratumoral glucose into massive H₂O₂, which are further converted into highly toxic hydroxyl radicals (•OH) by the catalysis of ferrocene via the Fenton reaction. Thereafter, induced by the ROS-responsive cleavage of thioketal linkage, the conjugated DOX prodrug was released and activated. The combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT) of PFW-DOX/GOD present anti-tumor effect with 96% of tumor inhibitory rate (TIR). Therefore, such tumor microenvironment-responsive supramolecular polypeptide nanoprodrugs represent a potential candidate for combination therapy with minimal side effects. STATEMENT OF SIGNIFICANCE: In this work, a tumor microenvironment-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) was prepared via pillar[5]arene-based host-guest interactions, and presented low side effects and high tumor accumulation owing to the diameters of about 200 nm and surface PEG segment. After pH-responsive release of GOD in the intracellular acidic environment, the cascade catalytic reactions including GOD-catalyzed degradation of intratumoral glucose and Fenton reaction, effectively happened to generate •OH for chemodynamic therapy (CDT), which subsequently induced the cleavage of thioketal linkage to activate free DOX for chemotherapy (CT). Collectively, this supramolecular polypeptide nanoprodrugs provide a promising strategy for combination therapy with synergetic anti-tumor effect.

The Advancement of Gas-Generating Nanoplatforms in Biomedical Fields: Current Frontiers and Future Perspectives

Diverse gases (NO, CO, H₂ S, H₂ , etc.) have been widely applied in the medical intervention of various diseases, including cancer, cardiovascular disease, ischemia-reperfusion injury, bacterial infection, etc., attributing to their inherent biomedical activities. Although many gases have many biomedical activities, their clinical use is still limited due to the rapid and free diffusion behavior of these gases molecules, which may cause potential side effects and/or ineffective treatment. Gas-generating nanoplatforms (GGNs) are effective strategies to address the aforementioned challenges of gas therapy by preventing gas production or release at nonspecific sites, enhancing GGNs accumulation at targeted sites, and controlling gas release in response to exogenous (UV, NIR, US, etc.) or endogenous (H₂ O₂ , GSH, pH, etc.) stimuli at the lesion site, further maintaining gas concentration within the effective range and achieving the purpose of disease treatment. This review comprehensively summarizes the advancements of "state-of-the-art" GGNs in the recent three years, with emphasis on the composition, structure, preparation process, and gas release mechanism of the nanocarriers. Furthermore, the therapeutic effects and limitations of GGNs in preclinical studies using cell/animal models are discussed. Overall, this review enlightens the further development of this field and promotes the clinical transformation of gas therapy.

Intelligent Supramolecular Nanoprodrug Based on Anionic Water-Soluble [2]Biphenyl-Extended-Pillar[6]arenes for Combination Therapy

An anionic water-soluble [2]biphenyl-extended-pillar[6]arenes modified with eight ammonium salt ions (AWBpP6) was successfully synthesized to establish a drug-drug conjugate supramolecular nanoprodrug (SNP) with a high drug-loading capacity. This SNP can generate a synergistic triple therapeutic effect of photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy (CT; i.e., PDT-PTT-CT) with excellent biocompatibility.

Syntheses of Polypeptides and Their Biomedical Application for Anti-Tumor Drug Delivery

Polypeptides have attracted considerable attention in recent decades due to their inherent biodegradability and biocompatibility. This mini-review focuses on various ways to synthesize polypeptides, as well as on their biomedical applications as anti-tumor drug carriers over the past five years. Various approaches to preparing polypeptides are summarized, including solid phase peptide synthesis, recombinant DNA techniques, and the polymerization of activated amino acid monomers. More details on the polymerization of specifically activated amino acid monomers, such as amino acid N-carboxyanhydrides (NCAs), amino acid N-thiocarboxyanhydrides (NTAs), and N-phenoxycarbonyl amino acids (NPCs), are introduced. Some stimuli-responsive polypeptide-based drug delivery systems that can undergo different transitions, including stability, surface, and size transition, to realize a better anti-tumor effect, are elaborated upon. Finally, the challenges and opportunities in this field are briefly discussed.

Recent Advances in Poly(α-L-glutamic acid)-Based Nanomaterials for Drug Delivery

Poly(α-L-glutamic acid) (PGA) is a class of synthetic polypeptides composed of the monomeric unit α-L-glutamic acid. Owing to their biocompatibility, biodegradability, and non-immunogenicity, PGA-based nanomaterials have been elaborately designed for drug delivery systems. Relevant studies including the latest research results on PGA-based nanomaterials for drug delivery have been discussed in this work. The following related topics are summarized as: (1) a brief description of the synthetic strategies of PGAs; (2) an elaborated presentation of the evolving applications of PGA in the areas of drug delivery, including the rational design, precise fabrication, and biological evaluation; (3) a profound discussion on the further development of PGA-based nanomaterials in drug delivery. In summary, the unique structures and superior properties enables PGA-based nanomaterials to represent as an enormous potential in biomaterials-related drug delivery areas.

pH/ROS dual-responsive supramolecular polypeptide prodrug nanomedicine based on host-guest recognition for cancer therapy

Supramolecular nanomedicine assembly combined with polypeptide prodrug could become a powerful strategy to minimize drug leakage in blood circulation and trigger sufficient drug release at tumor tissue. Here, we developed a charge-reversal amphiphilic pillar[5]arene-modified polypeptide (P5-PLL-DMA), and reactive oxygen species (ROS)-sensitive polypeptide prodrug (P-PLL-DOX) including a ROS-cleavable thioketal (TK) linker between doxorubicin (DOX) and poly(_L-lysine) (PLL), which could assemble via pillar[5]arene host-guest recognition, and further encapsulate chlorin e6 (Ce6) to obtain a supramolecular polypeptide prodrug (SPP-DOX/Ce6). The chemical conjugation to load drugs of DOX and the negatively charge of SPP-DOX/Ce6 could prevent premature drug leakage, and reduce undesirable interaction with serum proteins to enhance stability under physiological conditions (pH 7.4). Simultaneously, the carried charge of SPP-DOX/Ce6 reversed from negative to positive could effectively enhance the cellular internalization for efficient DOX delivery under acidic tumor microenvironment (pH 6.5). Upon 660 nm near-infrared light (NIR) irradiation, the ROS generated by encapsulated Ce6 rapidly cleaved the TK linker to release activated DOX, inducing the tumor-specific drug delivery. This intelligent supramolecular polypeptide prodrug based on pillar[5]arene host-guest recognition represents new avenues to develop stimulus responsive prodrug for enhanced cancer therapy with minimized the side effect. STATEMENT OF SIGNIFICANCE: In this work, a pH/ROS dual-sensitive supramolecular polypeptide prodrug (SPP-DOX/Ce6) was developed to minimize drug leakage in blood circulation and trigger sufficient drug release at tumor tissue. The chemical conjugation to load drugs of DOX via a ROS-cleavable thioketal (TK) linker and the distinctive charge-reversal capacity of SPP-DOX/Ce6 significantly enhances the stability under physiological conditions (pH 7.4), while facilitates cellular uptake at tumor site (pH 6.8). Upon 660 nm near-infrared light (NIR) irradiation, the ROS generated by encapsulated Ce6 induces the rapid cleavage of TK linker to release activated DOX, achieving a tumor-specific drug delivery. This intelligent supramolecular polypeptide prodrug SPP-DOX/Ce6 provides an effective strategy to construct stimulus responsive prodrug for enhanced cancer therapy.

Nanotechnology-based combinatorial phototherapy for enhanced cancer treatment

Nanotechnology-based phototherapy has attracted enormous attention to cancer treatment owning to its non-invasiveness, high controllability and accuracy. Given the fast development of anti-tumor strategies, we summarize various examples of multifunctional nanosystems to highlight the recent advances in nanotechnology-based combinatorial phototherapy towards improving cancer treatment. The limitations of the monotherapeutic approach and the superiority of the photo-involved combinatorial strategies are discussed in each part. The future breakthroughs and clinical perspectives of combinatorial phototherapy are also outlooked. Our perspectives may inspire researchers to develop more effective phototherapy-based cancer-treating approaches.

Pillar[5]arene based glyco-targeting nitric oxide nanogenerator for hyperthermia-induced triple-mode cancer therapy

Nitric oxide (NO)-mediated gas therapy (GT) and alkyl radical (R•) therapy (ART) are emerging cancer therapy modes, and multi-mode therapy has been recognized as an attractive strategy for enhancing anti-cancer efficacy. In this work, a thermal-responsive R• initiator 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIBI)-loaded glycol-targeting NO nanogenerator was constructed by first the covalent conjugation of thermal-responsive NO donor of S-nitrosothiols (RSNO) on the surface of mesoporous silica-coated gold nanorods (AuNRs@MSN), then the coating of a supramolecular complex of amino pillar[5]arene (NP5) and galactose derivative (G), and finally the loading of AIBI. The glycol-targeting NO nanogenerator demonstrated specific targeting ability to HepG2 cells owing to the recognition between galactose residues and asialoglycoprotein receptors (ASGPR). Specially, upon 808 nm near-infrared (NIR) irradiation, the AIBI-loaded NO nanogenerator generated hyperthermia to achieve photothermal therapy (PTT), and further GT and ART resulted from the thermal responsiveness of RSNO and AIBI, respectively. In vitro experiments revealed that the AIBI-loaded glyco-targeting NO nanogenerator had good biocompatibility and exhibited effective inhibition to the proliferation of HepG2 cells. This work provides a novel way to supramolecular hybrid drug delivery systems for triple-mode targeting therapy of PTT/GT/ART.

Polydopamine-drug conjugate nanocomposites based on ZIF-8 for targeted cancer photothermal-chemotherapy

Stimuli-responsive prodrug-based nanoplatform with synergistic antitumor activity is of central importance to the development of promising nanomedicines for cancer therapy. Here, we describe a polydopamine-drug conjugate nanocomposite (ZP-PDA-DOX) with targeted cancer photothermal-chemotherapy (PTT-CT), which constructed by a gradual copolymerization of dopamine (DA) and pH-sensitive dopamine-derived prodrug (DA-DOX) into the porous channels of zeolite imidazolate frameworks-8 (ZIF-8), followed by PEGylation with amino-terminated folic acid-polyethylene glycol (NH₂ -PEG-FA) to acquire the high biocompatibility, specificity, and excellent tumor-targeting property. The incorporation of polydopamine strengthened the stability and dispersion of ZIF-8, and also conferred photothermal conversion effect. In the tumor acidic microenvironment, the acid-labile hydrazone linker of DA-DOX and ZIF-8 promptly degraded to release activated DOX. Moreover, the generated hyperthermia due to the high photothermal conversion efficiency of PDA component could accelerate drug release, and simultaneously thermally ablate tumor tissue to maximize the DOX-induced CT, which could also assist PTT to eradicate tumor cells. This study provides a promising strategy for targeted cancer PTT-CT with synergistic anti-tumor effect.

Stimuli Responsive Nitric Oxide-Based Nanomedicine for Synergistic Therapy

Gas therapy has received widespread attention from the medical community as an emerging and promising therapeutic approach to cancer treatment. Among all gas molecules, nitric oxide (NO) was the first one to be applied in the biomedical field for its intriguing properties and unique anti-tumor mechanisms which have become a research hotspot in recent years. Despite the great progress of NO in cancer therapy, the non-specific distribution of NO in vivo and its side effects on normal tissue at high concentrations have impaired its clinical application. Therefore, it is important to develop facile NO-based nanomedicines to achieve the on-demand release of NO in tumor tissue while avoiding the leakage of NO in normal tissue, which could enhance therapeutic efficacy and reduce side effects at the same time. In recent years, numerous studies have reported the design and development of NO-based nanomedicines which were triggered by exogenous stimulus (light, ultrasound, X-ray) or tumor endogenous signals (glutathione, weak acid, glucose). In this review, we summarized the design principles and release behaviors of NO-based nanomedicines upon various stimuli and their applications in synergistic cancer therapy. We also discuss the anti-tumor mechanisms of NO-based nanomedicines in vivo for enhanced cancer therapy. Moreover, we discuss the existing challenges and further perspectives in this field in the aim of furthering its development.

A-DA'D-A fused-ring small molecule-based nanoparticles for combined photothermal and photodynamic therapy of cancer

New nanoparticles (Y6 NPs) based on the A-DA'D-A fused-ring conjugated small molecule Y6 have been prepared for the combined photothermal and photodynamic therapy of cancer. Y6 NPs show excellent light absorption from 300 to 900 nm, a good photothermal conversion efficiency of 57% and reactive oxygen species generation capability. The high photothermal conversion ability and superior photodynamic activity of Y6 NPs endow them with great potential for cancer therapy.

Inherently nitric oxide containing polymersomes remotely regulated by NIR for improving multi-modal therapy on drug resistant cancer

The therapeutic potential of nitric oxide (NO) has been highly attractive to tumor treatment, especially for surmounting the multidrug resistance (MDR) of cancer. However, the NO-involved therapy remains extremely challenging because of the difficulty to simultaneously control the NO release rate and real-time concentration. Herein, we construct NO-containing polymersomes with high amount of NO donors inherently grown on the polymer chains to keep the stability. These polymersomes can be simultaneously loaded with photosensitizer of IR780 iodide on the membrane layer and chemotherapeutic of DOX·HCl in the lumen. NO release can be triggered by the reduction conditions, and further accelerated by remote NIR irradiation due to the increased local temperature. The instantaneous NO release with high concentration significantly inhibits the P-gp expression and sensitize the chemotherapy, thus overcoming the tumor MDR and improving the anti-tumor activity. Meanwhile, DOX·HCl release is highly promoted at the intracellular conditions because of the cleavage of acid-labile cis-aconitic amide at endo/lysosomal pH, and the improved hydrophilicity of the membrane layer after NO release. The in vivo results show that the single intravenous injection of polymersome formulation companying with NIR irradiation exerts multi-modal therapies of chemotherapy, PTT/PDT, and NO-therapy on the MCF-7/R tumor models, showing superior and combinational treatment efficacy with the complete eradication of tumors and few side effects.

Stimuli-responsive polypeptide nanoassemblies: Recent progress and applications in cancer nanomedicine

Stimuli-responsive polypeptide nanoassemblies exhibit great potentials for cancer nanomedicines because of desirable biocompatibility and biodegradability, unique secondary conformations, varying functionalities, and especially the stimuli-enhanced therapeutic efficacy and reduced side effect. This review introduces the design and fabrication of stimuli-responsive polypeptide nanoassemblies that exhibit endogenous stimuli (e.g., pH, reduction, reactive oxygen species, adenosine triphosphate and enzyme, etc.) and exogenous light stimuli (e.g., UV and near-infrared light), which are biologically related or applied in the clinic. We also discuss the applications and prospects of those stimuli-responsive polypeptide nanoassemblies that might overcome the biological barriers of cancer nanomedicines for in vivo administration. Much more effort is needed to accelerate the second-generation stimuli-responsive polypeptide nanomedicines for clinical transition and applications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A convergent synthetic platform for polymeric nanoparticle for the treatment of combination colorectal cancer therapy

In biomaterials and drug delivery, the development of polymeric therapies capable of the synchronized release of several therapeutic agents remains an important challenge. In this article, we describe the development of polymeric nanoparticles (PNPs) with precise molar ratios of Curcumin (CUR) and Methotrexate (MEX). The highly symmetric synthetic approach allows for the development of novel NPs-based combination therapeutic strategies for colorectal cancer. The fabricated CUR/MEX@PNPs were confirmed by transmission microscopy (TEM) and the size and polydispersity index were assessed through the dynamic light scattering (DLS). CUR and MEX were released slowly from the drug delivery without any burst impact. Furthermore, CUR/MEX@PNPs exhibited dose-responsive cytotoxic effects in CL40 and SW1417 cells, with a greater cell death ratio than that of free drugs. The drugs-loaded polymeric nanomaterials were more easily taken up by cancer cells in vitro, according to the cellular uptake analysis. The apoptotic features were confirmed by various fluorescence staining assay. The results of the fluorescent assay reveal that the nanomaterials remarkably induce apoptosis in colorectal cancer cells. Further, the apoptosis cell death mechanism was displayed that these nanomaterials significantly induce apoptosis in the targeted cancer cells. Overall, the current investigation confirmed that CUR/MEX@PNPs could be used to successfully combat colorectal cancers in the immediate future.HighlightsWe have developed the Curcumin (CUR) and Methotrexate (MEX) encapsulated polymeric nanoparticles (CUR/MEX@PNPs).CUR/MEX@PNPs confirmed by the various analytical methods.CUR/MEX@PNPs enhanced the in vitro proliferation against the colorectal cancer cells.Biochemical analysis results reveals that CUR/MEX@PNPs induce apoptosis.The apoptosis was confirmed by Annexin-V-FITC and PI for flow cytometry.

Recent Advances in Cyanine-Based Phototherapy Agents

Phototherapies, in the form of photodynamic therapy (PDT) and photothermal therapy (PTT), are very promising treatment modalities for cancer since they provide locality and turn-on mechanism for toxicity, both of which are critical in reducing off-site toxicity. Irradiation of photosensitive agents demonstrated successful therapeutic outcomes; however, each approach has its limitations and needs to be improved for clinical success. The combination of PTT and PDT may work in a synergistic way to overcome the limitations of each method and indeed improve the treatment efficacy. The development of single photosensitive agents capable of inducing both PDT and PTT is, therefore, extremely advantageous and highly desired. Cyanine dyes are shown to have such potential, hence have been very popular in the recent years. Luminescence of cyanine dyes renders them as phototheranostic molecules, reporting the localization of the photosensitive agent prior to irradiation to induce phototoxicity, hence allowing image-guided phototherapy. In this review, we mainly focus on the cyanine dye-based phototherapy of different cancer cells, concentrating on the advancements achieved in the last ten years.

Photo-responsive prodrug nanoparticles for efficient cytoplasmic delivery and synergistic photodynamic-chemotherapy of metastatic triple-negative breast cancer

Triple-negative breast cancer (TNBC) have been considered as the most malignant subtype of breast cancer with leading incidence and mortality among females. Herein, photo-responsive prodrug nanoparticles (AlP/CPT-NPs) were designed with efficient cytoplasmic delivery of anti-cancer agent for cooperative photodynamic-chemotherapy. AlP/CPT-NPs were prepared using photosensitizer Al(III) phthalocyanine chloride disulfonic acid (AlP) and ROS-activatable camptothecin prodrug (CPT-PD). AlP/CPT-NPs could induce intracellular ¹O₂ generation upon light exposure, which not only initiate immediate disassembly of AlP/CPT-NPs but also promote cytoplasmic delivery of CPT through ¹O₂-mediated lysosomal rupture. The released intracellular CPT could be translocated into nuclei in only 5 min post-irradiation. Consequently, AlP/CPT-NPs efficiently suppressed the tumor growth and metastasis of TNBC in a spatiotemporally controlled manner, providing a promising option for effective treatment of metastatic TNBC. STATEMENT OF SIGNIFICANCE: Breast cancer is a complex disease with leading incidence among females, in which triple-negative breast cancer (TNBC) is considered as the most malignant subtype with increased risk of resistance, recurrence and metastasis. Herein, we designed photo-responsive prodrug nanoparticles (AlP/CPT-NPs) for synergistic treatment of metastatic TNBC. Upon 660 nm light exposure, the ¹O₂ generated by AlP/CPT-NPs could initiate immediate disassembly of AlP/CPT-NPs and further promote cytoplasmic delivery of the therapeutic payloads (camptothecin, CPT). The prepared AlP/CPT-NPs induced potent in vivo phototherapeutic damage through photodynamic-chemotherapy, resulting in complete tumor ablation with metastasis suppression.