Stimuli-Responsive "Cluster Bomb" for Programmed Tumor Therapy

Smart self-transforming nano-systems for overcoming biological barrier and enhancing tumor treatment efficacy

Nanomedicines need to overcome multiple biological barriers in the body to reach the target area. However, traditional nanomedicines with constant physicochemical properties are not sufficient to meet the diverse and sometimes conflicting requirements during in vivo transport, making it difficult to penetrate various biological barriers, resulting in suboptimal drug delivery efficiency. Smart self-transforming nano-systems (SSTNs), capable of altering their own physicochemical properties (including size, charge, hydrophobicity, stiffness, morphology, etc.) under different physiological conditions, hold the potential to break through multiple biological barriers, thereby improving drug delivery efficiency and the efficacy of cancer treatment. In this review, we first summarize the design strategies of five most popular SSTNs (such as size-, charge-, hydrophilicity-, stiffness-, and morphology-self-transforming nano-systems), and then delve into their biomedical applications in enhancing circulation time, tissue penetration, and cellular uptake. Finally, we discuss the opportunities and challenges that SSTNs face in the future for cancer treatment and diagnosis.

Recent progress on transition metal dichalcogenide-based composites for cancer therapy

Cancer remains a global health challenge, driving the need for advanced treatments. While transition metal dichalcogenides (TMDs) show promise in cancer therapy, their stability and efficacy require improvement. This study explores TMD-based composites as a solution to enhance their therapeutic potential. This review begins by providing an overview of TMDs and emphasizing their preparation techniques and fundamental properties. The focus is then shifted to categorizing TMD-based composites based on their constituent materials, delving into various types, such as TMD-organic, TMD-carbon, TMD-metal chalcogenide, TMD-metal, and TMD-oxide composites, as well as more complex ternary and multinary systems. We further explore key fabrication strategies, including hydrothermal/solvothermal methods and surface deposition/coating techniques. Subsequently, the focus shifted to their applications in cancer treatment, including chemotherapy, photothermal therapy, phototherapy, and integrated combination therapies. Finally, critical challenges in the field and perspectives on potential directions for future research are presented.

Size-transformable nanotherapeutics for cancer therapy

The size of nanodrugs plays a crucial role in shaping their chemical and physical characteristics, consequently influencing their therapeutic and diagnostic interactions within biological systems. The optimal size of nanomedicines, whether small or large, offers distinct advantages in disease treatment, creating a dilemma in the selection process. Addressing this challenge, size-transformable nanodrugs have surfaced as a promising solution, as they can be tailored to entail the benefits associated with both small and large nanoparticles. In this review, various strategies are summarized for constructing size-transformable nanosystems with a focus on nanotherapeutic applications in the field of biomedicine. Particularly we highlight recent research developments in cancer therapy. This review aims to inspire researchers to further develop various toolboxes for fabricating size-transformable nanomedicines for improved intervention against diverse human diseases.

Enhancing hepatocellular carcinoma therapy with DOX-loaded SiO2 nanoparticles via mTOR-TFEB pathway autophagic flux inhibition

Chemotherapeutic drugs often fail to provide long-term efficacy due to their lack of specificity and high toxicity. To enhance the biosafety and reduce the side effects of these drugs, various nanocarrier delivery systems have been developed. In this study, we loaded the anticancer drug doxorubicin (DOX) and an MRI contrast agent into silica nanoparticles, coating them with pH-responsive and tumor cell-targeting polymers. These polymers enable the carrier to achieve targeted delivery and controlled drug release in acidic environments. This integrated diagnostic and therapeutic strategy successfully achieved both the diagnosis and treatment of liver cancer. Additionally, we demonstrated that the nanocarrier inhibits autophagic flux in liver cancer cells by targeting the autophagy-lysosome pathway and regulating the nuclear translocation of TFEB, thereby promoting tumor cell death. This novel diagnostic-integrated nanocarrier is expected to be a promising tool for targeted liver cancer treatment.

A review on dendrimer-based nanoconjugates and their intracellular trafficking in cancer photodynamic therapy

Nanotechnology-based cancer treatment has received considerable attention, and these treatments generally use drug-loaded nanoparticles (NPs) to target and destroy cancer cells. Nanotechnology combined with photodynamic therapy (PDT) has demonstrated positive outcomes in cancer therapy. Combining nanotechnology and PDT is effective in targeting metastatic cancer cells. Nanotechnology can also increase the effectiveness of PDT by targeting cells at a molecular level. Dendrimer-based nanoconjugates (DBNs) are highly stable and biocompatible, making them suitable for drug delivery applications. Moreover, the hyperbranched structures in DBNs have the capacity to load hydrophobic compounds, such as photosensitizers (PSs) and chemotherapy drugs, and deliver them efficiently to tumour cells. This review primarily focuses on DBNs and their potential applications in cancer treatment. We discuss the chemical design, mechanism of action, and targeting efficiency of DBNs in tumour metastasis, intracellular trafficking in cancer treatment, and DBNs' biocompatibility, biodegradability and clearance properties. Overall, this study will provide the most recent insights into the application of DBNs and PDT in cancer therapy.

Polypeptides-Based Nanocarriers in Tumor Therapy

Cancer remains a worldwide problem, and new treatment strategies are being actively developed. Peptides have the characteristics of good biocompatibility, strong targeting, functional diversity, modifiability, membrane permeable ability, and low immunogenicity, and they have been widely used to construct targeted drug delivery systems (DDSs). In addition, peptides, as endogenous substances, have a high affinity, which can not only regulate immune cells but also work synergistically with drugs to kill tumor cells, demonstrating significant potential for application. In this review, the latest progress of polypeptides-based nanocarriers in tumor therapy has been outlined, focusing on their applications in killing tumor cells and regulating immune cells. Additionally, peptides as carriers were found to primarily provide a transport function, which was also a subject of interest to us. At the end of the paper, the shortcomings in the construction of peptide nano-delivery system have been summarized, and possible solutions are proposed therein. The application of peptides provides a promising outlook for cancer treatment, and we hope this article can provide in-depth insights into possible future avenues of exploration.

Tumor Homing Chimeric Peptide Rhomboids to Improve Photodynamic Performance by Inhibiting Therapy-Upregulated Cyclooxygenase-2

Negative therapeutic feedback of inflammation would extensively attenuate the antitumor effect of photodynamic therapy (PDT). In this work, tumor homing chimeric peptide rhomboids (designated as NP-Mel) are fabricated to improve photodynamic performance by inhibiting PDT-upregulated cyclooxygenase-2 (COX-2). The hydrophobic photosensitizer of protoporphyrin IX (PpIX) and palmitic acid are conjugated onto the neuropilin receptors (NRPs) targeting peptide motif (CGNKRTR) to obtain tumor homing chimeric peptide (Palmitic-K(PpIX)CGNKRTR), which can encapsulate the COX-2 inhibitor of meloxicam. The well dispersed NP-Mel not only improves the drug stability and reactive oxygen species (ROS) production ability, but also increase the breast cancer targeted drug delivery to intensify the PDT effect. In vitro and in vivo studies verify that NP-Mel will decrease the secretion of prostaglandin E2 (PGE2) after PDT treatment, inducing the downregulation of IL-6 and TNF-α expressions to suppress PDT induced inflammation. Ultimately, an improved PDT performance of NP-Mel is achieved without inducing obvious systemic toxicity, which might inspire the development of sophisticated nanomedicine in consideration of the feedback induced therapeutic resistance.

Enzyme-Responsive Modular Peptides Enhance Tumor Penetration of Quantum Dots via Charge Reversal Strategy

Quantum dots (QDs) are colloidal semiconductor nanoparticles acting as fluorescent probes for detection, disease diagnosis, and photothermal and photodynamic therapy. However, their performance in cancer treatment is limited by inadequate tumor accumulation and penetration due to the larger size of nanoparticles compared to small molecules. To address this challenge, charge reversal nanoparticles offer an effective strategy to prolong blood circulation time and achieve enhanced endocytosis and tumor penetration. In this study, we leveraged the overexpressed γ-glutamyl transpeptidase (GGT) in many human tumors and developed a library of modular peptides to serve as water-soluble surface ligands of QDs. We successfully transferred the QDs from the organic phase to the aqueous phase within 5 min. And through systematic tuning of the peptide sequence, we optimized the fluorescent stability of QDs and their charge reversal behavior in response to GGT. The resulting optimal peptide stabilized QDs in aqueous solution with a high fluorescent retention rate of 93% after three months and realized the surface charge reversal of QDs triggered by GGT in vitro. The binding between the peptide and QD surface was investigated by using saturation transfer differential nuclear magnetic resonance (STD NMR). Thanks to its charge reversal ability, the GGT-responsive QDs exhibited enhanced cellular uptake in GGT-expressing cancer cells and deeper penetration in the 3D multicellular spheroids. This enzyme-responsive modular peptide can lead to specific tumor targeting and deeper tumor penetration, holding great promise to enhance the treatment efficacy of QD-based theranostics.

Cell Membrane Coated pH-Responsive Intelligent Bionic Delivery Nanoplatform for Active Targeting in Photothermal Therapy

Aim

To produce pH-responsive bionic high photothermal conversion nanoparticles actively targeting tumors for sensitizing photothermal therapy (PTT).

Materials and Methods

The bionic nanoparticles (ICG-PEI@HM NPs) were prepared by electrostatic adsorption of indocyanine green (ICG) coupled to polyethyleneimine (PEI) and modified with tumor cell membranes. In vitro and in vivo experiments were conducted to investigate the efficacy of ICG-PEI@HM-mediated PTT.

Results

The intelligent responsiveness of ICG-PEI@HM to pH promoted the accumulation of ICG and enhanced the PTT performance of ICG-PEI@HM NPs. Compared with free ICG, NPs exhibited great photothermal stability, cellular uptake, and active tumor targeting for PTT.

Conclusion

ICG-PEI@HM NPs can enhance the efficacy of PTT and can be used as a new strategy for the construction of photothermal agents.

Synergistic chemo-photo anticancer therapy by using reversible Diels-Alder dynamic covalent bond mediated polyprodrug amphiphiles and immunoactivation investigation

Highly efficient endocytosis and multi-approach integrated therapeutic tactics are important factors in oncotherapy. With the aid of thermally reversible furan-maleimide dynamic covalent bonds and the "polyprodrug amphiphiles" concept, thermo- and reduction-responsive PEG(-COOH)Fu/MI(-SS-)CPT copolymers were fabricated by the Diels-Alder (D-A) coupling of hydrophilic Fu(-COOH)-PEG and hydrophobic MI(-SS-)-CPT building blocks. The copolymers could self-assemble to form composite nanoparticles with a photothermal conversion reagent (IR780) and maintain excellent stability. In the in vitro simulated environments, the composite nanoparticles could detach Fu(-COOH)-PEG chains by a retro-D-A reaction upon near-infrared light (NIR) irradiation and reduce the size to facilitate endocytosis. Once in the intracellular environment, glutathione (GSH) could trigger a cascade reaction to release active CPT drugs to achieve chemotherapy, which could be further promoted by NIR light induced photothermal therapy. The in vivo mouse tumor model experiments demonstrated that these nanoparticles had an excellent therapeutic effect on solid tumors and inhibited their recurrence. Not only that, the synergistic chemical and optical therapy induced body immune response was also systematically evaluated; the maturation of dendritic cells, the proliferation of T cells, the increase of high mobility group box protein 1, and the decrease of immunosuppressive regulatory T cells confirmed that such synergistic therapy could effectively provide immune protection to the body. We believe such in situ generation of small-sized therapeutic units brought by a dynamically reversible D-A reaction could expand the pathway to design next generation drug delivery systems possessing superior design philosophy and excellent practice effects compared to currently available ones.

Overcoming tumor microenvironment obstacles: Current approaches for boosting nanodrug delivery

In order to achieve targeted delivery of anticancer drugs, efficacy improvement, and side effect reduction, various types of nanoparticles are employed. However, their therapeutic effects are not ideal. This phenomenon is caused by tumor microenvironment abnormalities such as abnormal blood vessels, elevated interstitial fluid pressure, and dense extracellular matrix that affect nanoparticle penetration into the tumor's interstitium. Furthermore, nanoparticle properties including size, charge, and shape affect nanoparticle transport into tumors. This review comprehensively goes over the factors hindering nanoparticle penetration into tumors and describes methods for improving nanoparticle distribution by remodeling the tumor microenvironment and optimizing nanoparticle physicochemical properties. Finally, a critical analysis of future development of nanodrug delivery in oncology is further discussed. STATEMENT OF SIGNIFICANCE: This article reviews the factors that hinder the distribution of nanoparticles in tumors, and describes existing methods and approaches for improving the tumor accumulation from the aspects of remodeling the tumor microenvironment and optimizing the properties of nanoparticles. The description of the existing methods and approaches is followed by highlighting their advantages and disadvantages and put forward possible directions for the future researches. At last, the challenges of improving tumor accumulation in nanomedicines design were also discussed. This review will be of great interest to the broad readers who are committed to delivering nanomedicine for cancer treatment.

Doxorubicin-Fe(III)-Gossypol Infinite Coordination Polymer@PDA:CuO2 Composite Nanoparticles for Cost-Effective Programmed Photothermal-Chemodynamic-Coordinated Dual Drug Chemotherapy Trimodal Synergistic Tumor Therapy

To achieve the maximum therapeutic effects and minimize adverse effects of trimodal synergistic tumor therapies, a cost-effective programmed photothermal (PTT)-chemodynamic (CDT)-coordinated dual drug chemotherapy (CT) trimodal synergistic therapy strategy in chronological order is proposed. According to the status or volumes of the tumors, the intensity and time of each therapeutic modality are optimized, and three modalities are combined programmatically and work in chronological order. The optimal synergistic therapy begins with high-intensity PTT for 10 min to ablate larger tumors, followed by medium-intensity CDT for several hours to eliminate medium-sized tumors, and then low-intensity coordinated dual drugs CT lasts over 48 h to clear smaller residual tumors. Composite nanoparticles, made of Fe-coordinated polydopamine mixed with copper peroxide as the cores and their surface dotted with lots of doxorubicin-Fe(III)-gossypol infinite coordination polymers (ICPs), have been developed to implement the strategy. These composite nanoparticles show excellent synergistic effects with the minimum dose of therapeutic agents and result in nearly 100% tumor inhibition for mice bearing PC-3 tumors and no observed recurrence within 60 days of treatment. The ratios of the different therapeutic agents in the composite nanoparticles can be adjusted to accommodate different types of tumors with this cost-effective programmed trimodal therapy strategy.

Multifunctional nanostructures: Intelligent design to overcome biological barriers

Over the past three decades, nanoscience has offered a unique solution for reducing the systemic toxicity of chemotherapy drugs and for increasing drug therapeutic efficiency. However, the poor accumulation and pharmacokinetics of nanoparticles are some of the key reasons for their slow translation into the clinic. The is intimately linked to the non-biological nature of nanoparticles and the aberrant features of solid cancer, which together significantly compromise nanoparticle delivery. New findings on the unique properties of tumors and their interactions with nanoparticles and the human body suggest that, contrary to what was long-believed, tumor features may be more mirage than miracle, as the enhanced permeability and retention based efficacy is estimated to be as low as 1%. In this review, we highlight the current barriers and available solutions to pave the way for approved nanoformulations. Furthermore, we aim to discuss the main solutions to solve inefficient drug delivery with the use of nanobioengineering of nanocarriers and the tumor environment. Finally, we will discuss the suggested strategies to overcome two or more biological barriers with one nanocarrier. The variety of design formats, applications and implications of each of these methods will also be evaluated.

Design of Disintegrable Nanoassemblies to Release Multiple Small-Sized Nanoparticles

The therapeutic and diagnostic effects of nanoparticles depend on the efficiency of their delivery to targeted tissues, such as tumors. The size of nanoparticles, among other characteristics, plays a crucial role in determining their tissue penetration and retention. Small nanoparticles may penetrate deeper into tumor parenchyma but are poorly retained, whereas large ones are distributed around tumor blood vessels. Thus, compared to smaller individual nanoparticles, assemblies of such nanoparticles due to their larger size are favorable for prolonged blood circulation and enhanced tumor accumulation. Upon reaching the targeted tissues, nanoassemblies may dissociate at the target region and release the smaller nanoparticles, which is beneficial for their distribution at the target site and ultimate clearance. The recent emerging strategy that combines small nanoparticles into larger, biodegradable nanoassemblies has been demonstrated by several groups. This review summarizes a variety of chemical and structural designs for constructing stimuli-responsive disintegrable nanoassemblies as well as their different disassembly routes. These nanoassemblies have been applied as demonstrators in the fields of cancer therapy, antibacterial infection, ischemic stroke recovery, bioimaging, and diagnostics. Finally, we summarize stimuli-responsive mechanisms and their corresponding nanomedicine designing strategies, and discuss potential challenges and barriers towards clinical translation.

The Recent Advance of Cell-Penetrating and Tumor-Targeting Peptides as Drug Delivery Systems Based on Tumor Microenvironment

Cancer has become the primary reason for industrial countries death. Although first-line treatments have achieved remarkable results in inhibiting tumors, they could have serious side effects because of insufficient selectivity. Therefore, specific localization of tumor cells is currently the main desire for cancer treatment. In recent years, cell-penetrating peptides (CPPs), as a kind of promising delivery vehicle, have attracted much attention because they mediate the high-efficiency import of large quantities of cargos in vivo and vitro. Unfortunately, the poor targeting of CPPs is still a barrier to their clinical application. In order to solve this problem, researchers use the various characteristics of tumor microenvironment and multiple receptors to improve the specificity toward tumors. This review focuses on the characteristics of the tumor microenvironment, and introduces the development of strategies and peptides based on these characteristics as drug delivery system in the tumor-targeted therapy.

Enzyme-Triggered Size-Switchable Nanosystem for Deep Tumor Penetration and Hydrogen Therapy

The poor penetration of nanocarriers within tumor dense extracellular matrices (ECM) greatly restricts the access of anticancer drugs to the deep tumor cells, resulting in low therapeutic efficacy. Moreover, the high toxicity of the traditional chemotherapeutics inevitably causes undesirable side effects. Herein, taking the advantages of biosafe H₂ and small-sized nanoparticles in diffusion within tumor ECM, we develop a matrix metalloprotease 2 (MMP-2) responsive size-switchable nanoparticle (UAMSN@Gel-PEG) that is composed of ultrasmall amino-modified mesoporous silica nanoparticles (UAMSN) wrapped within a PEG-conjugated gelatin to deliver H₂ to the deep part of tumors for effective gas therapy. Ammonia borane (AB) is chosen as the H₂ prodrug that can be effectively loaded into UAMSN by hydrogen-bonding adsorption. Gelatin is used as the substrate of MMP-2 to trigger size change and block AB inside UAMSN during blood circulation. PEG is introduced to further increase the particle size and endow the nanoparticle with long blood circulation to achieve effective tumor accumulation via the EPR effect. After accumulation into the tumor site, MMP-2 promptly digests gelatin to expose UAMSN loading AB for deep tumor penetration. Upon stimulation by the acidic tumor microenvironment, AB decomposes into H₂ for further intratumor diffusion to achieve effective hydrogen therapy. Consequently, such a simultaneous deep tumor penetration of nanocarriers and H₂ results in an evident suppression on tumor growth in a 4T1 tumor-bearing model without any obvious toxicity on normal tissues. Our synthetic nanosystem provides a promising strategy for the development of nanomedicines with enhanced tumor permeability and good biosafety for efficient tumor treatment.

Tungsten-based Nanomaterials in the Biomedical Field: A Bibliometric Analysis of Research Progress and Prospects

Tungsten-based nanomaterials (TNMs) with diverse nanostructures and unique physicochemical properties have been widely applied in the biomedical field. Although various reviews have described the application of TNMs in specific biomedical fields, there are still no comprehensive studies that summarize and analyze research trends of the field as a whole. To identify and further promote the development of biomedical TNMs, a bibliometric analysis method is used to analyze all relevant literature on this topic. First, general bibliometric distributions of the dataset by year, country, institute, referenced source, and research hotspots are recognized. Next, a comprehensive review of the subjectively recognized research hotspots in various biomedical fields, including biological sensing, anticancer treatments, antibacterials, and toxicity evaluation, is provided. Finally, the prospects and challenges of TNMs are discussed to provide a new perspective for further promoting their development in biomedical research.

Synergistically Enhancing Tumor Chemotherapy Using an Aggregation-Induced Emission Photosensitizer on Covalently Conjugated Molecularly Imprinted Polymer Nanoparticles

Due to the polygenic and heterogeneous nature of the tumorigenesis process, traditional chemotherapy is far from desirable. Fabricating multifunctional nanoplatforms integrating photodynamic effect can synergistically enhance chemotherapy because they can make the cancer cells much sensitive to chemotherapeutics. However, how to assemble different units in nanoplatforms and minimize side effects caused by chemodrugs and photosensitizers (PSs) still needs to be explored. Herein, a nanoplatform CPP/PS-MIP@DOX is developed using a simultaneously covalently conjugated new aggregation-induced emission (AIE) PS and a cell-penetrating peptide (CPP) on the surface of silica-based molecularly imprinted polymer (MIP) nanoparticles, prepared with doxorubicin (DOX) as the template in the water system via a sol-gel technique. CPP/PS-MIP@DOX has good biocompatibility, high DOX-loading ability, promoted cellular uptake, and sustained and pH-sensitive drug release capability. Furthermore, it can efficiently penetrate into tumor tissue, accurately home to, and accumulate at the tumor site. As a result, a better efficacy with lower cytotoxicity is achieved with a smaller dosage of DOX by utilizing either the photodynamic effect or unique characteristics of the MIP. It is the first nanoplatform fabricated by chemically conjugating AIE PSs directly on the surface of the scaffold via the surface-decorated strategy and successfully applied in cancer therapy. This work provides an effective strategy by constructing AIE PS-based cancer nanomedicines with MIPs as scaffolds.

The role of imaging in targeted delivery of nanomedicine for cancer therapy

Nanomedicines overcome the pharmacokinetic limitations of traditional drug formulations and have promising prospect in cancer treatment. However, nanomedicine delivery in vivo is still facing challenges from the complex physiological environment. For the purpose of effective tumor therapy, they should be designed to guarantee the five features principle, including long blood circulation, efficient tumor accumulation, deep matrix penetration, enhanced cell internalization and accurate drug release. To ensure the excellent performance of the designed nanomedicine, it would be better to monitor the drug delivery process as well as the therapeutic effects by real-time imaging. In this review, we summarize strategies in developing nanomedicines for efficiently meeting the five features of drug delivery, and the role of several imaging modalities (fluorescent imaging (FL), magnetic resonance imaging (MRI), computed tomography (CT), photoacoustic imaging (PAI), positron emission tomography (PET), and electron microscopy) in tracing drug delivery and therapeutic effect in vivo based on five features principle.

Dual-Stage Irradiation of Size-Switchable Albumin Nanocluster for Cascaded Tumor Enhanced Penetration and Photothermal Therapy

The triple-negative breast cancer (TNBC) microenvironment makes a feature of aberrant vasculature, high interstitial pressure, and compact extracellular matrix, which combine to reduce the delivery and penetration of therapeutic agents, bringing about incomplete elimination of cancer cells. Herein, employing the tumor penetration strategy of size-shrinkage combined with ligand modification, we constructed a photothermal nanocluster for cascaded deep penetration in tumor parenchyma and efficient eradication of TNBC cells. In our approach, the photothermal agent indocyanine green (ICG) is laded in human serum albumin (HSA), which is cross-linked by a thermally labile azo linker (VA057) and then further modified with a tumor homing/penetrating tLyP-1 peptide (HP), resulting in a TNBC-targeting photothermal-responsive size-switchable albumin nanocluster (ICG@HSA-Azo-HP). Aided by the enhanced permeability and retention effect and guidance of HP, the ca. 149 nm nanoclusters selectively accumulate in the tumor site and then, upon mild irradiation with the 808 nm laser, disintegrate into 11 nm albumin fractions that possess enhanced intratumoral diffusion ability. Meanwhile, HP initiates the CendR pathway among the nutrient-deficient tumor cells and facilitates the transcellular delivery of the nanocluster and its disintegrated fractions for subsequent therapy. By employing this size-shrinkage and peptide-initiated transcytosis strategy, ICG@HSA-Azo-HP possesses excellent penetration capabilities and shows extensive penetration depth in three-dimensional multicellular tumor spheroids after irradiation. Moreover, with a superior photothermal conversion effect, the tumor-penetrating nanocluster can implement effective photothermal therapy throughout the tumor tissue under a second robust irradiation. Both in vivo orthotopic and ectopic TNBC therapy confirmed the efficient tumor inhibition of ICG@HSA-Azo-HP after dual-stage irradiation. The synergistic penetration strategy of on-demanded size-shrinkage and ligand guidance accompanied by clinically feasible NIR irradiation provides a promising approach for deep-penetrating TNBC therapy.

Triggering cell death in cancers using self-illuminating nanocomposites

Bioinspired photocatalysis has resulted in efficient solutions for many areas of science and technology spanning from solar cells to medicine. Here we show a new bioinspired semiconductor nanocomposite (nanoTiO₂-DOPA-luciferase, TiDoL) capable of converting light energy within cancerous tissues into chemical species that are highly disruptive to cell metabolism and lead to cell death. This localized activity of semiconductor nanocomposites is triggered by cancer-generated activators. Adenosine triphosphate (ATP) is produced in excess in cancer tissues only and activates nearby immobilized TiDoL composites, thereby eliminating its off-target toxicity. The interaction of TiDoL with cancerous cells was probed in situ and in real-time to establish a detailed mechanism of nanoparticle activation, triggering of the apoptotic signaling cascade, and finally, cancer cell death. Activation of TiDoL with non-cancerous cells did not result in cell toxicity. Exploring the activation of antibody-targeted semiconductor conjugates using ATP is a step toward a universal approach to single-cell-targeted medical therapies with more precision, efficacy, and potentially fewer side effects.

Physically stimulus-responsive nanoparticles for therapy and diagnosis

Nanoparticles offer numerous advantages in various fields of science, particularly in medicine. Over recent years, the use of nanoparticles in disease diagnosis and treatments has increased dramatically by the development of stimuli-responsive nano-systems, which can respond to internal or external stimuli. In the last 10 years, many preclinical studies were performed on physically triggered nano-systems to develop and optimize stable, precise, and selective therapeutic or diagnostic agents. In this regard, the systems must meet the requirements of efficacy, toxicity, pharmacokinetics, and safety before clinical investigation. Several undesired aspects need to be addressed to successfully translate these physical stimuli-responsive nano-systems, as biomaterials, into clinical practice. These have to be commonly taken into account when developing physically triggered systems; thus, also applicable for nano-systems based on nanomaterials. This review focuses on physically triggered nano-systems (PTNSs), with diagnostic or therapeutic and theranostic applications. Several types of physically triggered nano-systems based on polymeric micelles and hydrogels, mesoporous silica, and magnets are reviewed and discussed in various aspects.

Polydopamine-doped supramolecular chiral hydrogels for postoperative tumor recurrence inhibition and simultaneously enhanced wound repair

Cancer recurrence remains a major challenge after primary tumor excision, and the inflammation of tumor-caused wounds can hinder wound healing and potentially promote tumor growth. Herein, a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel system encapsulated with polydopamine nanoparticles (PDA-NPs) has been developed in order to prevent tumor relapse after surgery and promote wound repair. PDA-NPs allow for near-infrared (NIR) light-triggered photothermal therapy, especially, it can scavenge free radicals in the surgical wound. LPFEG can mimic native extracellular matrix (ECM) structure to create a chiral microenvironment that enhances fibroblast adhesion, proliferation, and new tissue regeneration. With anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is significantly enhanced by the integration of chemo-photothermal therapy both in vitro and in vivo. The PDA-based chiral supramolecular composite hydrogel as an effective postoperative adjuvant possesses promising applicable prospects in inhibiting tumor recurrence and accelerating wound healing after operation. STATEMENT OF SIGNIFICANCE: After primary tumor excision, cancer recurrence remains a severe concern, and the inflammation induced by tumor-related wounds can delay wound healing. Herein, we designed a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel platform that was co-assembled with polydopamine nanoparticles (PDA-NPs). Among them, PDA-NPs can offer photothermal therapy and scavenge free radicals in surgical wounds. LPFEG can create a chiral microenvironment that promotes fibroblast adhesion, proliferation, and new tissue regeneration. Furthermore, with anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is considerably boosted. Therefore, the PDA-based chiral supramolecular hydrogel shows high application potential as a postoperative adjuvant in preventing tumor relapse as well as accelerating wound healing after surgery.

Low Intensity Focused Ultrasound Ignited “Deep-Penetration Nanobomb” (DPNB) for Tetramodal Imaging Guided Hypoxia-Tolerant Sonodynamic Therapy Against Hypoxic Tumors

Background

Sonodynamic therapy (SDT) has been regarded as a novel therapeutic modality for killing tumors. However, the hypoxic tumor microenvironment, especially deep-seated tumors distant from blood vessels, severely restricts therapeutic efficacy due to the oxygen-dependent manner of SDT.

Methods

Herein, we report a novel ultrasonic cavitation effect-based therapeutic modality that is able to facilitate the hypoxia-tolerant SDT for inducing hypoxic tumor death. A tLyP-1 functionalized liposomes is fabricated, composed of hematoporphyrin monomethyl ether gadolinium as the sonosentizer and perfluoropentane (PFP) as the acoustic environment regulator. Moreover, the tLyP-1 functioned liposomes could achieve active tumor homing and effective deep-penetrating into hypoxic tumors. Upon low intensity focused ultrasound (LIFU) irradiation, the acoustic droplet vaporization effect of PFP induced fast liquid-to-gas transition and quick bubbles explosion to generate hydroxyl radicals, efficiently promoting cell death in both normoxic and hypoxic microenvironment (acting as deep-penetration nanobomb, DPNB).

Results

The loading of PFP is proved to significantly enhance the therapeutic efficacy of hypoxic tumors. In particular, these DPNB can also act as ultrasound, photoacoustic, magnetic resonance, and near-infrared fluorescence tetramodal imaging agents for guiding the therapeutic process.

Conclusion

This study is the first report involving that liquid-to-gas transition based SDT has the potential to combat hypoxic tumors.

Recent advances in smart nanoplatforms for tumor non-interventional embolization therapy

Tumor embolization therapy has attracted great attention due to its high efficiency in inhibiting tumor growth by cutting off tumor nutrition and oxygen supply by the embolic agent. Although transcatheter arterial embolization (TAE) is the mainstream technique in the clinic, there are still some limitations to be considered, especially the existence of high risks and complications. Recently, nanomaterials have drawn wide attention in disease diagnosis, drug delivery, and new types of therapies, such as photothermal therapy and photodynamic therapy, owing to their unique optical, thermal, convertible and in vivo transport properties. Furthermore, the utilization of nanoplatforms in tumor non-interventional embolization therapy has attracted the attention of researchers. Herein, the recent advances in this area are summarized in this review, which revealed three different types of nanoparticle strategies: (1) nanoparticles with active targeting effects or stimuli responsiveness (ultrasound and photothermal) for the safe delivery and responsive release of thrombin; (2) tumor microenvironment (copper and phosphate, acidity and GSH/H2O2)-responsive nanoparticles for embolization therapy with high specificity; and (3) peptide-based nanoparticles with mimic functions and excellent biocompatibility for tumor embolization therapy. The benefits and limitations of each kind of nanoparticle in tumor non-interventional embolization therapy will be highlighted. Investigations of nanoplatforms are undoubtedly of great significance, and some advanced nanoplatform systems have arrived at a new height and show potential applications in practical applications.

Lipoprotein-biomimetic nanostructure enables tumor-targeted penetration delivery for enhanced photo-gene therapy towards glioma

Glioma is one of the most malignant primary tumors affecting the brain. The efficacy of therapeutics for glioma is seriously compromised by the restriction of blood-brain barrier (BBB), interstitial tumor pressure of resistance to chemotherapy/radiation, and the inevitable damage to normal brain tissues. Inspired by the natural structure and properties of high-density lipoprotein (HDL), a tumor-penetrating lipoprotein was prepared by the fusion tLyP-1 to apolipoprotein A-I-mimicking peptides (D4F), together with indocyanine green (ICG) incorporation and lipophilic small interfering RNA targeted HIF-1α (siHIF) surface anchor for site-specific photo-gene therapy. tLyP-1 peptide is fused to HDL-surface to facilitate BBB permeability, tumor-homing capacity and -site accumulation of photosensitizer and siRNA. Upon NIR light irradiation, ICG not only served as real-time targeted imaging agent, but also provided toxic reactive oxygen species and local hyperthermia for glioma phototherapy. The HIF‐1α siRNA in this nanoplatform downregulated the hypoxia‐induced HIF‐1α level in tumor microenvironment and enhanced the photodynamic therapy against glioma. These studies demonstrated that the nanoparticles could not only efficiently across BBB and carry the payloads to orthotopic glioma, but also modulate tumor microenvironment, thereby inhibiting tumor growth with biosafety. Overall, this study develops a new multifunctional drug delivery system for glioma theranostic, providing deeper insights into orthotopic brain tumor imaging and treatment.

•A tumor-penetrating lipoprotein was designed to functionalize natural HDL into multifunctional nanoplatform for codelivery of ICG and siHIF in amplified fluorescence imaging-guided photo-gene therapy.

•Ascribed to the natural structure of HDL and the distinct properties of tLyP-1, the established ptHDL/siHIF-ICG can achieve markable BBB crossing and deep tumor penetration for site-specific drug delivery.

•Non-destructive monitoring and diagnosis of glioma in situ via the photosensitizer ICG.

•Modulation of tumor microenvironment related to hypoxia by gene siHIF and enhanced PDT efficacy.

Supramolecular Core-Shell Nanoassemblies with Tumor Microenvironment-Triggered Size and Structure Switch for Improved Photothermal Therapy

Photothermal therapy (PTT) is demonstrated to be an effective methodology for cancer treatment. However, the relatively low photothermal conversion efficiency, limited tumor accumulation, and penetration still remain to be challenging issues that hinder the clinical application of PTT. Herein, the core-shell hierarchical nanostructures induced by host-guest interaction between water-soluble pillar[5]arene (WP5) and polyethylene glycol-modified aniline tetramer (TAPEG) are constructed. The pH-responsive performance endows the core-shell nanostructures with size switchable property, with an average diameter of 200 nm in the neutral pH and 60 nm in the acidic microenvironment, which facilitates not only tumor accumulation but also tumor penetration. Moreover, the structure switch of WP5⊃TAPEG under acidic microenvironment and the dual mechanism regulated extending of п conjugate, inclusion in the hydrophobic cavity of WP5 and the dense distribution in the core-shell structured assemblies, dramatically enhance the absorption in the near-infrared-II region and, further, the photothermal conversion efficiency (60.2%). The as-designed intelligent nanoplatform is demonstrated for improved antitumor efficacy via PTT.

Nanoarchitectured prototypes of mesoporous silica nanoparticles for innovative biomedical applications

Despite exceptional morphological and physicochemical attributes, mesoporous silica nanoparticles (MSNs) are often employed as carriers or vectors. Moreover, these conventional MSNs often suffer from various limitations in biomedicine, such as reduced drug encapsulation efficacy, deprived compatibility, and poor degradability, resulting in poor therapeutic outcomes. To address these limitations, several modifications have been corroborated to fabricating hierarchically-engineered MSNs in terms of tuning the pore sizes, modifying the surfaces, and engineering of siliceous networks. Interestingly, the further advancements of engineered MSNs lead to the generation of highly complex and nature-mimicking structures, such as Janus-type, multi-podal, and flower-like architectures, as well as streamlined tadpole-like nanomotors. In this review, we present explicit discussions relevant to these advanced hierarchical architectures in different fields of biomedicine, including drug delivery, bioimaging, tissue engineering, and miscellaneous applications, such as photoluminescence, artificial enzymes, peptide enrichment, DNA detection, and biosensing, among others. Initially, we give a brief overview of diverse, innovative stimuli-responsive (pH, light, ultrasound, and thermos)- and targeted drug delivery strategies, along with discussions on recent advancements in cancer immune therapy and applicability of advanced MSNs in other ailments related to cardiac, vascular, and nervous systems, as well as diabetes. Then, we provide initiatives taken so far in clinical translation of various silica-based materials and their scope towards clinical translation. Finally, we summarize the review with interesting perspectives on lessons learned in exploring the biomedical applications of advanced MSNs and further requirements to be explored.

Binary regulation of the tumor microenvironment by a pH-responsive reversible shielding nanoplatform for improved tumor chemo-immunotherapy

The limited infiltration of specific T cells in an immunosuppressive microenvironment is a major challenge for cancer immunotherapy. Reversing tumor microenvironment and inducing an antitumor immune response are crucial for cancer therapy. Here, phenylboronic acid (PBA) derivative-stabilized ultrasmall platinum nanoparticles (PBA-Pt) and dextran-coated BLZ-945 nanoparticles (DNPs) were co-assembled through a pH-responsive borate ester bond to construct a versatile reversible shielding multifunctional nanoplatform (Pt@DNPs) for the first time. Pt@DNPs dissociated into two individual components, namely PBA-Pt and DNPs, in the tumor acid microenvironment. Both in vitro and in vivo studies revealed that Pt@DNPs induced immunogenic cell death (ICD) (through multimechanisms involving Pt^Ⅱ release and a multienzyme catalytic process by PBA-Pt) and relieved immunosuppressive microenvironment (depletion of tumor-associated macrophages by BLZ-945), which led to tumor-associated antigen release, maturation of dendritic cells, and infiltration of cytotoxic T cells for efficient antitumor immune response against both primary tumor and pulmonary metastatic tumor nodules. Therefore, Pt@DNPs is a promising option for cancer chemo-immunotherapy. STATEMENT OF SIGNIFICANCE: A versatile reversible shielding multifunctional nanoplatform (Pt@DNPs) was engineered for the first time for combinational cancer chemo-immunotherapy. Multimechanisms involving induction of immunogenic cell death by PBA-Pt and sufficient TAM depletion by DNPs could efficiently relieve tumor immunosuppressive microenvironment and activate the antitumor immune response. The synergistic effect not only increased the infiltration of specific T cells in primary tumor, but it also induced a strong immune response against pulmonary metastatic nodules. Collectively, this nanoplatform may represent a promising strategy for combinational chemo-immunotherapy for cancers.

Current trends in smart mesoporous silica-based nanovehicles for photoactivated cancer therapy

Photoactivated therapeutic strategies (photothermal therapy and photodynamic therapy), due to the adjusted therapeutic area, time and light dosage, have prevailed for the fight against tumors. Currently, the monotherapy with limited treatment effect and undesired side effects is gradually replaced by multimodal and multifunctional nanosystems. Mesoporous silica nanoparticles (MSNs) with unique physicochemical advantages, such as huge specific surface area, controllable pore size and morphology, functionalized modification, satisfying biocompatibility and biodegradability, are considered as promising candidates for multimodal photoactivated cancer therapy. Excitingly, the innovative nanoplatforms based on the mesoporous silica nanoparticles provide more and more effective treatment strategies and display excellent antitumor potential. Given the rapid development of antitumor strategies based on MSNs, this review summarizes the current progress in MSNs-based photoactivated cancer therapy, mainly consists of (1) photothermal therapy-related theranostics; (2) photodynamic therapy-related theranostics; (3) multimodal synergistic therapy, such as chemo-photothermal-photodynamic therapy, phototherapy-immunotherapy and phototherapy-radio therapy. Based on the limited penetration of irradiation light in photoactivated therapy, the challenges faced by deep-seated tumor therapy are fully discussed, and future clinical translation of MSNs-based photoactivated cancer therapy are highlighted.

An all-in-one nanoplatform with near-infrared light promoted on-demand oxygen release and deep intratumoral penetration for synergistic photothermal/photodynamic therapy

Hypoxia and high-density extracellular matrix within the tumor microenvironment (TME) strengthens tumor resistance to the oxygen-dependent cancer therapy. Herein, an on-demand oxygen released nanoplatform (MONs/IR780/PFC-O₂@BSA, BMIPO) that was triggered by near-infrared (NIR) light combined with TME has been designed for achieving synergistic photothermal/photodynamic therapy with deep intratumoral penetration and oxygen self-sufficiency. Notably, the zeta potential and transmission electron microscope (TEM) results indicated that such "smart" BMIPO nanoplatform possessed good colloidal stability and on-demand TME-specific degradability. This characteristic of the BMIPO nanoplatform allows it to simultaneously achieve high tumor accumulation and deep intratumoral penetration. The results of the O₂ loading and release measurements showed that the as- prepared BMIPO possessed excellent O₂ reversibly bind/release performance. Furthermore, the photothermal effect of NIR dye (IR780) accelerated the dissociation of TME-responsive BMIPO, as a result, it achieved an on-demand, continuous and complete O₂ release to relieve tumor hypoxia during phototherapy. In vitro and in vivo results demonstrated that the as-prepared all-in-one nanoplatform have successfully realized NIR-triggered on-demand O₂ release, nanocarrier-mediated glutathione (GSH) reducing, hyperthermia-promoted deep intratumoral penetration and dual-model imaging-guided precise cancer therapy. This work would provide inspiration for the design of nanoplatforms with on-demand release and deep intratumoral penetration for achieving high-efficiency synergistic photothermal/photodynamic therapy in hypoxic tumors.

Rapid pH-responsive self-disintegrating nanoassemblies balance tumor accumulation and penetration for enhanced anti-breast cancer therapy

The dilemma of tumor accumulation and deep penetration has always been a barrier in antitumor therapy. Stimuli-responsive size changeable drug delivery systems provide possible solutions. Nevertheless, the low size-shrinkage efficiency limited the antitumor effects. In this study, an instant pH-responsive size shrinkable nanoassemblies named self-aggregated DOX@HA-CD (SA-DOX@HA-CD) was formulated using small-sized hyaluronic acid modified carbon dots (HA-CD) as monomers, which could self-aggregate into raspberry-like structure via hydrophobicity force in neutral pH and rapidly disassemble into shotgun-like DOX-loaded CD monomer in simulated tumor microenvironment (pH 6.5), owing to the transformation in electrical charge and hydrophobicity/hydrophilicity of this system. The transmission electron microscopy showed that the clustered SA-DOX@HA-CD had a diameter of ~150 nm, and thoroughly disassembled into ~30 nm nanoparticles in response to acidic environment. The disassemble efficiency was approximately 100%. Attributed to this property, SA-DOX@HA-CD led to enhanced cellular internalization and accumulation in 4T1 cells in simulated tumor microenvironment, as well as deep tumor penetration in 3D tumor spheroid model. Besides, the imine bond between DOX and HA-CD endowed DOX with pH-responsive release profile in the acidic lysosome environment. Furthermore, in the orthotopic 4T1 tumor-bearing mouse model, SA-DOX@HA-CD demonstrated higher tumor accumulation than non-aggregated DOX-HA-CD. Meanwhile, in response to the acid tumor microenvironment, the dissociated DOX-HA achieved deep tumor penetration, which consequently resulted in 2.5-fold higher antitumor efficiency. The formulation of self-aggregated SA-DOX@HA-CD provides a simple and effective alternative to prepare pH-responsive size-shrinkable nanodrug delivery systems. STATEMENT OF SIGNIFICANCE: The heterogeneity of tumor vasculature and the high tumor interstitial pressure lead to the barriers in tumor accumulation and deep penetration, which calls for opposite properties (e.g. size) of drug delivery systems. To address this dilemma, various size changeable nanoparticles have been developed utilizing special features of tumor microenvironment, such as pH, enzyme and reactive oxygen species. Nevertheless, the current strategies face the problems of incomplete hydrolysis of chemical bonds or insufficient enzyme degradation, which result in only partial size shrinkage, hindering the tumor deep penetration effects. Here we developed a self-assembled nanocluster, which could respond to acidic pH rapidly and thoroughly disassemble into small nanodots due to the alteration of hydrophobicity/hydrophilicity/charge, leading to approximately 100% dissociation. This strategy provides a new concept for design of size changeable drug delivery systems.

NIR-triggerable ROS-responsive cluster-bomb-like nanoplatform for enhanced tumor penetration, phototherapy efficiency and antitumor immunity

The restricted tumor penetration has been regarded as the Achilles' Heels of most nanomedicines, largely limiting their efficacy. To address this challenge, a cluster-bomb-like nanoplatform named CPIM is prepared, which for the first time combines size-transforming and transcytosis strategies, thus enhancing both passive and active transport. For passive diffusion, the "cluster-bomb" CPIM (135 nm) releases drug-loaded "bomblets" (IR780/1-methyl-tryptophan (1 MT) loaded PAMAM, <10 nm) in response to the high reactive-oxygen-species (ROS) concentration in tumor microenvironment (TME), which promotes intratumoral diffusion. Besides, IR780 generates ROS upon NIR irradiation and intensifies this responsiveness; therefore, there exists a NIR-triggered self-destructive behavior, rendering CPIM spatiotemporal controllability. For active transport, the nanoplatform is proven to be delivered via transcytosis with/without NIR irradiation. Regarding the anti-cancer performance, CPIM strengthens the photodynamic therapy (PDT)/photothermal therapy (PTT) activity of IR780 and IDO pathway inhibition effect of 1 MT, thus exhibiting a strongest inhibitory effect on primary tumor. CPIM also optimally induces immunogenic cell death, reverses the "cold" TME to a "hot" one and evokes systemic immune response, thus exerting an abscopal and anti-metastasis effects. In conclusion, this work provides a facile, simple yet effective strategy to enhance the tumor penetration, tumor-killing effect and antitumor immunity of nanomedicines.

An endogenous stimulus detonated nanocluster-bomb for contrast-enhanced cancer imaging and combination therapy

Exploitation of stimuli-responsive nanoplatforms is of great value for precise and efficient cancer theranostics. Herein, an in situ activable "nanocluster-bomb" detonated by endogenous overexpressing legumain is fabricated for contrast-enhanced tumor imaging and controlled gene/drug release. By utilizing the functional peptides as bioligands, TAMRA-encircled gold nanoclusters (AuNCs) endowed with targeting, positively charged and legumain-specific domains are prepared as quenched building blocks due to the AuNCs' nanosurface energy transfer (NSET) effect on TAMRA. Importantly, the AuNCs can shelter therapeutic cargos of DNAzyme and Dox (Dzs-Dox) to aggregate larger nanoparticles as a "nanocluster-bomb" (AuNCs/Dzs-Dox), which could be selectively internalized into cancer cells by integrin-mediated endocytosis and in turn locally hydrolyzed in the lysosome with the aid of legumain. A "bomb-like" behavior including "spark-like" appearance (fluorescence on) derived from the diminished NSET effect of AuNCs and cargo release (disaggregation) of Dzs-Dox is subsequently monitored. The results showed that the AuNC-based disaggregation manner of the "nanobomb" triggered by legumain significantly improved the imaging contrast due to the activable mechanism and the enhanced cellular uptake of AuNCs. Meanwhile, the in vitro cytotoxicity tests revealed that the detonation strategy based on AuNCs/Dzs-Dox readily achieved efficient gene/chemo combination therapy. Moreover, the super efficacy of combinational therapy was further demonstrated by treating a xenografted MDA-MB-231 tumor model in vivo. We envision that our multipronged design of theranostic "nanocluster-bomb" with endogenous stimuli-responsiveness provides a novel strategy and great promise in the application of high contrast imaging and on-demand drug delivery for precise cancer theranostics.

An injectable and biodegradable nano-photothermal DNA hydrogel enhances penetration and efficacy of tumor therapy

The biological barrier of solid tumors hinders deep penetration of nanomedicine, constraining anticancer treatment. Moreover, the inherent multidrug resistance (MDR) of cancer tissues may further limit the efficacy of anti-tumor nanomedicine. We synthesized highly permeable, photothermal, injectable, and positively charged biodegradable nucleic acid hydrogel (DNA-gel) nanoparticles to deliver cancer drugs. The nanoparticles are derived from photothermal materials containing black phosphorus quantum dots (BPQDs). The intra-tumoral BPQDs improve the sensitivity of tumor cells to photothermal therapy (PTT) and photodynamic treatment (PDT). Tumor cells take up the positively charged and controllable size DNA-gel nanoparticles, facilitating easy penetration and translocation of the particles across and within the cells. Mouse models demonstrated the anti-tumor activity of the DNA gel nanoparticles in vivo. In particular, the DNA gel nanoparticles enhanced clearance of both small and large tumor masses. Just 20 days after treatment, the tumor masses had been cleared. Compared to DOX chemotherapy alone, the DNA-gel treatment also significantly reduced drug resistance and improved the overall survival of mice with orthotopic breast tumors (83.3%, 78 d). Therefore, DNA gel nanoparticles are safe and efficient supplements for cancer therapy.

GSH-Sensitive Nanoscale Mn3+-Sealed Coordination Particles as Activatable Drug Delivery Systems for Synergistic Photodynamic-Chemo Therapy

Activatable nanoscale drug delivery systems (NDDSs) are promising in maximizing cancer specificity and anticancer efficacy, and a multifunctional metal-organic nanomaterial is one of the new star NDDSs which requires further exploration. Herein, a novel DOX@MnCPs/PEG NDDSs were constructed by first synthesizing Mn³⁺-sealed coordination particles (MnCPs), modified with a targeted PEGylated polymer, and then loading anticancer drug doxorubicin (DOX). MnCPs were prepared from the assembly of Mn³⁺ ions and hematoporphyrin monomethyl ether (HMME) molecules. Furthermore, MnCPs had an average size of ∼100 nm and a large surface area (∼52.6 m² g^-1) and porosity (∼3.6 nm). After the loading of DOX, DOX@MnCPs/PEG exhibited a high DOX-loading efficacy of 27.2%, and they reacted with glutathione (GSH) to confer structural collapse, leading to the production of Mn²⁺ ions for enhanced magnetic resonance imaging (MRI), free HMME for augmented photodynamic effect, and free DOX for chemotherapy. As a consequence, these DOX@MnCPs/PEG NDDSs after intravenous injection showed efficient tumor homing and then exerted an obvious suppression for tumor growth rate by synergistic photodynamic-chemo therapy in vivo. Importantly, most of the DOX@MnCPs/PEG NDDSs could be gradually cleared through the renal pathway, and the remaining part could slowly be metabolized via the feces, enabling high biosafety. Therefore, this work provides a type of GSH-sensitive NDDS with biosafety, caner specificity, and multifunctionality for high synergistic treatment efficacy.

Adapting and Remolding: Orchestrating Tumor Microenvironment Normalization with Photodynamic Therapy by Size Transformable Nanoframeworks

Abnormal tumor microenvironment (TME) facilitates tumor proliferation and metastasis and establishes physiological barriers for effective transport of therapeutics inside the tumor, posing great challenges for cancer treatment. We designed a core-satellite size transformable nanoframework (denoted as T-PFRT) that can synchronously adapt to and remold TME for augmenting photodynamic therapy to inhibit tumor growth and prevent tumor metastasis. Upon matrix metalloproteinase 2 (MMP2)-responsive dissociation of the nanoframework in TME, the core structure loaded with TGFβ signaling pathway inhibitor and oxygen-carrying hemoglobin aims to stroma remodeling and hypoxia relief, allowing photosensitizer-encapsulated satellite particles to penetrate to deep-seated tumor for oxygen-fueled photodynamic therapy. T-PFRT could overcome the stroma and hypoxia barriers for delivering therapeutics and gain excellent therapeutic outcomes in the treatment of primary and metastatic tumors.

A smart viral vector for targeted delivery of hydrophobic drugs

Targeted delivery of hydrophobic chemotherapeutic drugs to tumor cells remains a fundamental problem in cancer therapy. Effective encapsulation of hydrophobic drugs in nano-vehicles can improve their pharmacokinetics, bioavailability and prevent off-target localization. We have devised a method for easy chemical conjugation and multivalent display of a tumor-homing peptide to virus-like particles of a non-mammalian virus, Flock House Virus (FHV), to engineer it into a smart vehicle for targeted delivery of hydrophobic drugs. This conjugation method provides dual functionalization to the VLPs, first, a 2 kDa PEG spacer arm shields VLPs from immune reactivity, and second, attachment of the tumor homing peptide tLyP-1 chauffeurs the encapsulated hydrophobic drugs to target cells. The fortuitous affinity of the FHV capsid towards hydrophobic molecules, and dependence on Ca²⁺ for maintaining a stable capsid shell, were utilized for incorporation of hydrophobic drugs—doxorubicin and ellipticine—in tLyP-1 conjugated VLPs. The drug release profile from the VLP was observed to be gradual, and strictly endosomal pH dependent. We propose that this accessible platform empowers surface functionalization of VLP with numerous ligands containing terminal cysteines, for generating competent delivery vehicles, antigenic display and other biomedical applications.

Hierarchical responsive micelle facilitates intratumoral penetration by acid-activated positive charge surface and size contraction

Integrating these features of acid-activated positively charged surface and size contraction into single nanoparticle would be an effective strategy for enhancing cellular uptake, intratumoral penetration and accumulation. Here, hierarchical responsive micelle (HVDMs) was developed via RAFT reaction as multifunctional polymer-drug conjugate for maximizing penetration and therapeutic effect against MCF-7 tumor by combining positively charged surface with size contraction: surface zeta-potential reversal (-2 to +12 mV) by protonation of PHEME and size contraction (~81-~41 nm) by simultaneous hydrophobic/hydrophilic conversion (pH ≈ 6.7); the disintegration of hydrazone bond between hydrophobic PVB and DOX triggered drug release (pH ≈ 5.0). The in vitro structural stabilization, cellular uptake and anti-proliferative efficiency were significantly higher than other control groups (CVDMs and HSDMs) at pH 6.7. The markedly increased penetration depth, cellular internalization and anti-tumor efficiency were confirmed in 3D MCSs spheroids at pH 6.7, and the ex vivo DOX fluorescence images further verified obvious penetration and accumulation in internal region of solid tumor. The antitumor effect in vivo demonstrated that HVDMs accelerated tumor atrophy, induced intratumoral cells apoptosis and alleviated system toxicity.

Advances in Multiple Stimuli-Responsive Drug-Delivery Systems for Cancer Therapy

Nanomedicines afford unique advantages in therapeutic intervention against tumors. However, conventional nanomedicines have failed to achieve the desired effect against cancers because of the presence of complicated physiological fluids and the tumor microenvironment. Stimuli-responsive drug-delivery systems have emerged as potential tools for advanced treatment of cancers. Versatile nano-carriers co-triggered by multiple stimuli in different levels of organisms (eg, extracorporeal, tumor tissue, cell, subcellular organelles) have aroused widespread interest because they can overcome sequential physiological and pathological barriers to deliver diverse therapeutic “payloads” to the desired targets. Furthermore, multiple stimuli-responsive drug-delivery systems (MSR-DDSs) offer a good platform for co-delivery of agents and reversing multidrug resistance. This review affords a comprehensive overview on the “landscape” of MSR-DDSs against tumors, highlights the design strategies of MSR-DDSs in recent years, discusses the putative advantage of oncotherapy or the obstacles that so far have hindered the clinical translation of MSR-DDSs.

Injectable hydrogel with MSNs/microRNA-21-5p delivery enables both immunomodification and enhanced angiogenesis for myocardial infarction therapy in pigs

Current therapeutic strategies such as angiogenic therapy and anti-inflammatory therapy for treating myocardial infarction have limited success. An effective approach may benefit from resolution of excessive inflammation combined with enhancement of angiogenesis. Here, we developed a microRNA-21-5p delivery system using functionalized mesoporous silica nanoparticles (MSNs) with additional intrinsic therapeutic effects. These nanocarriers were encapsulated into an injectable hydrogel matrix (Gel@MSN/miR-21-5p) to enable controlled on-demand microRNA-21 delivery triggered by the local acidic microenvironment. In a porcine model of myocardial infarction, we demonstrated that the released MSN complexes notably inhibited the inflammatory response by inhibiting the polarization of M1 macrophage within the infarcted myocardium, while further microRNA-21-5p delivery by MSNs to endothelial cells markedly promoted local neovascularization and rescued at-risk cardiomyocytes. The synergy of anti-inflammatory and proangiogenic effects effectively reduced infarct size in a porcine model of myocardial infarction.

Polydopamine-carbon dots functionalized hollow carbon nanoplatform for fluorescence-imaging and photothermal-enhanced thermochemotherapy

The low power photothermal therapy can reduce the tissue damage caused by laser irradiation, thus the near-infrared (NIR) absorbing vehicles with high photothermal conversion efficiency are demanded in the low power treatment. Herein, the NIR-absorbing agent polydopamine (PDA) and carbon dots (CDs) were gated on the openings of hollow mesoporous carbon (HMC) to construct a photothermal enhanced multi-functional system (HMC-SS-PDA@CDs). Interestingly, the fluorescence emission wavelength of HMC-SS-PDA@CDs was red-shifted by FRET effect between PDA and CDs, which solved the dilemma of fluorescence quenching of carbon-based materials and was more conducive to cell imaging. The modification of PDA@CDs not only acts as the gatekeepers to realize multi-responsive release of pH, GSH and NIR, but also endows the HMC vehicle with excellent photothermal generation capacity, the possibility for bio-imaging as well as the enhanced stability. Naturally, both the cytological level and the multicellular tumor sphere level demonstrate that the delivery system has good low-power synergistic therapeutic with combination index (CI) of 0.348 and imaging effects. Meanwhile, the combined treatment group showed the highest tumor inhibition rate of 92.6% at 0.75 W/cm². Therefore, DOX/HMC-SS-PDA@CDs nano-platform had broad application prospects in low power therapy and convenient imaging of carbon-based materials.

Self-Propelled and Near-Infrared-Phototaxic Photosynthetic Bacteria as Photothermal Agents for Hypoxia-Targeted Cancer Therapy

Hypoxia can increase the resistance of tumor cells to radiotherapy and chemotherapy. However, the dense extracellular matrix, high interstitial fluid pressure, and irregular blood supply often serve as physical barriers to inhibit penetration of drugs or nanodrugs across tumor blood microvessels into hypoxic regions. Therefore, it is of great significance and highly desirable to improve the efficiency of hypoxia-targeted therapy. In this work, living photosynthetic bacteria (PSB) are utilized as hypoxia-targeted carriers for hypoxic tumor therapy due to their near-infrared (NIR) chemotaxis and their physiological characteristics as facultative aerobes. More interestingly, we discovered that PSB can serve as a kind of photothermal agent to generate heat through nonradiative relaxation pathways due to their strong photoabsorption in the NIR region. Therefore, PSB integrate the properties of hypoxia targeting and photothermal therapeutic agents in an "all-in-one" manner, and no postmodification is needed to achieve hypoxia-targeted cancer therapy. Moreover, as natural bacteria, noncytotoxic PSB were found to enhance immune response that induced the infiltration of cytotoxicity T lymphocyte. Our results indicate PSB specifically accumulate in hypoxic tumor regions, and they show a high efficiency in the elimination of cancer cells. This proof of concept may provide a smart therapeutic system in the field of hypoxia-targeted photothermal therapeutic platforms.

Highly Penetrable and On-Demand Oxygen Release with Tumor Activity Composite Nanosystem for Photothermal/Photodynamic Synergetic Therapy

A deep penetrating and pH-responsive composite nanosystem was strategically developed to improve the efficacy of synergetic photothermal/photodynamic therapy (PTT/PDT) against hypoxic tumor. The designed nanosystem ([PHC]PP@HA NPs) was constructed by coloading hemoglobin (Hb) and chlorin e6 on polydopamine to build small-sized PHC NPs, which were encapsulated inside the polymer micelles (poly(ethylene glycol)-poly(ethylenimine)) and then capped with functionalized hyaluronic acid. The pH-responsive feature made [PHC]PP@HA NPs retain an initial size of ∼140 nm in blood circulation but rapidly release small PHC NPs (∼10 nm) with a high tumor-penetrating ability in the tumor microenvironment. The in vitro penetration experiment showed that the penetration depth of PHC NPs in the multicellular tumor spheroids exceeded 110 μm. The [PHC]PP@HA NPs exhibited excellent biocompatibility, deep tumor permeability, high photothermal conversion efficiency (47.09%), and low combination index (0.59) under hypoxic conditions. Notably, the nanosystem can freely adjust the release of oxygen and damaging PHC NPs in an on-demand manner on the basis of the feedback of tumor activity. This feedback tumor therapy significantly improved the synergistic effect of PTT/PDT and reduced its toxic side effects. The in vivo antitumor results showed that the tumor inhibition rate of [PHC]PP@HA NPs with an on-demand oxygen supply of Hb was ∼100%, which was much better than those of PTT alone and Hb-free nanoparticles ([PC]PP@HA NPs). Consequently, the [PHC]PP@HA NP-mediated PTT/PDT guided by feedback tumor therapy achieved an efficient tumor ablation with an extremely low tumor recurrence rate (8.3%) 60 d later, indicating the versatile potential of PTT/PDT.