Polyion Complex Vesicles for Photoinduced Intracellular Delivery of Amphiphilic Photosensitizer

A Photoactivatable Self-Assembled Nanoagonist for Synergistic Therapy against Pancreatic Ductal Adenocarcinoma

Immunotherapy has revolutionized the cancer treatment paradigm, yet efficient immunotherapeutic responses against immune-cold/desert cancers remain challenging. Herein, we report that photoactivatable nanoagonists yield a potent antitumor synergy of photoimmunotherapy against pancreatic ductal adenocarcinoma (PDAC). The nanoagonist was fabricated by assembling an amphiphilic boron dipyrromethene-derived polymer conjugated with a Toll-like receptor agonist via a photocleavable linker and stimulator of interferon genes agonist. The nanoagonist enables light-induced generation of reactive oxygen species and on-demand release of the agonists to yield synergistic photoimmunotherapy. The produced tumor antigens promote dendritic cell maturation, which is further amplified by these agonists for eliciting adaptive immunity, accompanied by apparently abscopal and long-term memory effects. The nanoagonist further alleviates the fibrosis of tumor stroma and the immunosuppressive microenvironment, leading to the deep infiltrations of clinically used therapeutics and immune cells to yield preferable combinational treatments against PDAC models. These results provide valuable insights into activatable nanoparticles for cancer therapy against immune-desert cancers.

Ampholytic Peptides Consisting of an Alternating Lysine/Glutamic Acid Sequence for the Simultaneous Formation of Polyion Complex Vesicles

Nanoarchitectures such as micelles and vesicles that self-assemble via electrostatic interactions between their charged polymeric components have been widely used as material delivery platforms. In this work, ampholytic peptides with a sequence of alternating lysine and glutamic acid residues were designed and synthesized via chemoenzymatic polymerization. This alternating sequence was achieved by trypsin-catalyzed polymerization of a dipeptide monomer. Due to the electrostatic interaction between the anionic and cationic residues, the prepared ampholytic peptides spontaneously formed nanosized assemblies with a size of 100-200 nm in water. Modification with tetra(ethylene glycol) (TEG) at the N-terminus of these ampholytic alternating peptides resulted in the formation of stable nanosized assemblies, while peptides consisting of random sequences of lysine and glutamic acid formed large aggregates with deteriorated stability even with TEG modification. Morphological observations using a field-emission scanning electron microscope and an atomic force microscope revealed that the obtained assemblies were spherical and hollow, indicating the spontaneous formation of vesicles from the TEG-modified ampholytic alternating peptides. These vesicles were able to encapsulate a model fluorescent protein within their hollow structures without structural collapse causing loss of fluorescence, demonstrating the potential of these nanocarriers for use in material delivery systems.

Enhancing Targeted Drug Delivery through Cell-Specific Endosomal Escape

Endosome is a major barrier in the intracellular delivery of drugs, especially for biologics, such as proteins, peptides, and nucleic acids. After being endocytosed, these cargos will be trapped inside the endosomal compartments and finally degraded in the lysosomes. Thus, various strategies have been developed to facilitate the escape of cargos from the endosomes to improve the intracellular delivery efficiency. While the majority of the studies are focusing on strengthening the endosomal escape capability to maximize the delivery outcome, recent evidence suggests that a careful control of the endosomal escape process could provide opportunity for targeted drug delivery. In this concept review, we examined current delivery systems that can sense intra-endosomal factors or external stimuli for controlling endosomal escape toward a targeted intracellular delivery of cargos. Furthermore, the prospects and challenges of such strategies are discussed.

Nanocarriers address intracellular barriers for efficient drug delivery, overcoming drug resistance, subcellular targeting and controlled release

The cellular barriers are major bottlenecks for bioactive compounds entering into cells to accomplish their biological functions, which limits their biomedical applications. Nanocarriers have demonstrated high potential and benefits for encapsulating bioactive compounds and efficiently delivering them into target cells by overcoming a cascade of intracellular barriers to achieve desirable therapeutic and diagnostic effects. In this review, we introduce the cellular barriers ahead of drug delivery and nanocarriers, as well as summarize recent advances and strategies of nanocarriers for increasing internalization with cells, promoting intracellular trafficking, overcoming drug resistance, targeting subcellular locations and controlled drug release. Lastly, the future perspectives of nanocarriers for intracellular drug delivery are discussed, which mainly focus on potential challenges and future directions. Our review presents an overview of intracellular drug delivery by nanocarriers, which may encourage the future development of nanocarriers for efficient and precision drug delivery into a wide range of cells and subcellular targets.

Inducing tumor ferroptosis via a pH-responsive NIR-II photothermal agent initiating lysosomal dysfunction

Ferroptosis is a unique programmed cell death process that was discovered a few years ago and plays an important role in tumor biology and treatment. However, it still remains a challenge to modulate tumor ferroptosis by spatiotemporally controlled cell-intrinsic Fenton chemistry. Herein, a pH activated photothermal sensitizer IR-PE has been designed and synthesized on the basis of cyanine bearing a diamine moiety, which is capable of triggering the lysosomal dysfunction-mediated Fenton pathway under the irradiation of near-infrared light to evoke ferroptosis, thereby improving antitumor efficacy and mitigating systemic side effects.

Aqueous coordination polymer complexes: From colloidal assemblies to bulk materials

1-dimensional (1D) coordination polymers refer to the macromolecules that have metal ions incorporated in their pendent groups or main chain through metal-binding ligand groups. They have intrinsic advantages over traditional polymers to regulate the polymer structures and functions owing to the nature of the metal-ligand bond. Consequently, they have great potential for the development of smart and functional structures and materials and therapeutic agents. Water-soluble 1D coordination polymers and assemblies are an important subtype of coordination polymers with distinctive interests for demanding applications in aqueous systems, such as biological and medical applications. This review highlights the recent progress and research achievements in the design and use of water-soluble 1D coordination polymers and assemblies. The overview covers the design and structure control of 1D coordination polymers, their colloidal assemblies, including nanoparticles, nanofibers, micelles and vesicles, and fabricated bulk materials such as membraneless liquid condensates, security ink, hydrogel actuators, and smart fabrics. Finally, we discuss the potential applications of several of these coordination polymeric structures and materials and give an outlook on the field of aqueous coordination polymers.

Recent advances in permeable polymersomes: fabrication, responsiveness, and applications

Polymersomes are vesicular nanostructures enclosed by a bilayer-membrane self-assembled from amphiphilic block copolymers, which exhibit higher stability compared with their biological analogues (e.g. liposomes). Due to their versatility, polymersomes have found various applications in different research fields such as drug delivery, nanomedicine, biological nanoreactors, and artificial cells. However, polymersomes prepared with high molecular weight components typically display low permeability to molecules and ions. It hence remains a major challenge to balance the opposing features of robustness and permeability of polymersomes. In this review, we focus on the design and strategies for fabricating permeable polymersomes, including polymersomes with intrinsic permeability, the formation of nanopores in the membrane bilayers by protein insertion, and the construction of stimuli-responsive polymersomes. Then, we highlight the applications of permeable polymersomes in the fields of biomimetic nanoreactors, artificial cells and organelles, and nanomedicine, to underline the challenges in the development of polymersomes as soft matter with biomedical utilities.

Terahertz Spectroscopy Sheds Light on Real-Time Exchange Kinetics Occurring through Plasma Membrane during Photodynamic Therapy Treatment

Methods to follow in real time complex processes occurring along living cell membranes such as cell permeabilization are rare. Here, the terahertz spectroscopy reveals early events in plasma membrane alteration generated during photodynamic therapy (PDT) protocol, events which are not observable in any other conventional biological techniques performed in parallel as comparison. Photodynamic process is examined in Madin-Darby canine kidney cells using Pheophorbide (Pheo) photosensitizer alone or alternatively encapsulated in poly(ethylene oxide)-block-poly(ε-caprolactone) micelles for drug delivery purpose. Terahertz spectroscopy (THz) reveals that plasma membrane permeabilization starts simultaneously with illumination and is stronger when photosensitizer is encapsulated. In parallel, the exchange of biological species is assessed. Over several hours, this conventional approach demonstrates significant differences between free and encapsulated Pheo, the latter leading to high penetration of propidium iodide, Na+ and Ca2+ ions, and a high level of leakage of K+ , ATP, and lactate dehydrogenase. THz spectroscopy provides, in a single measurement, the relative number of defects per membrane surface created after PDT, which is not achieved by any other method, providing early, sensitive real-time information. THz spectroscopy is therefore a promising technique and can be applied to any biological topic requiring the examination of short-term plasma membrane permeabilization.

Ultrasound-Triggered Piezocatalysis for Selectively Controlled NO Gas and Chemodrug Release to Enhance Drug Penetration in Pancreatic Cancer

Nitric oxide (NO) is drawing widespread attention in treating pancreatic ductal adenocarcinoma (PDAC) as a safe and therapeutically efficient technique through modulating the dense fibrotic stroma in the tumor microenvironment to enhance drug penetration. Considerable NO nanogenerators and NO releasing molecules have been developed to shield the systemic toxicity caused by free diffusion of NO gas. However, on-demand controlled release of NO and chemotherapy drugs at tumor sites remains a problem limited by the complex and dynamic tumor microenvironment. Herein, we present an ultrasound-responsive nanoprodrug of CPT-t-R-PEG₂₀₀₀@BaTiO₃ (CRB) which encapsulates piezoelectric nanomaterials barium titanate nanoparticle (BaTiO₃) with amphiphilic prodrug molecules that consisted of thioketal bond (t) linked chemotherapy drug camptothecin (CPT) and NO-donor l-arginine (R). Based on ultrasound-triggered piezocatalysis, BaTiO₃ can continuously generate ROS in the hypoxic tumor environment, which induces a cascade of reaction processes to break the thioketal bond to release CPT and oxidize R to release NO, simultaneously delivering CPT and NO to the tumor site. It is revealed that CRB shows a uniform size distribution, prolonged blood circulation time, and excellent tumor targeting ability. Moreover, controlled release of CPT and NO were observed both in vitro and in vivo under the stimulation of ultrasound, which is beneficial to the depletion of dense stroma and subsequently enhanced delivery and efficacy of CPT. Taken together, CRB significantly increased the antitumor efficacy against highly malignant Panc02 tumors in mice through inhibiting chemoresistance, representing a feasible approach for targeted therapies against Panc02 and other PDAC.

Fluorescent COFs with a Highly Conjugated Structure for Combined Starvation and Gas Therapy

Covalent organic frameworks (COFs) show great potential in biomedicine, but the synthesis of fluorescent ones with a highly conjugated structure in mild conditions remains a challenge. Herein, we reported a facile method to synthesize a nanosized, highly conjugated, and N-enriched COF material with bright fluorescence and further integrated it as a novel nanoplatform for efficient cancer starvation/gas therapy. High surface area and a porous structure endowed COFs with large loading capacity for both glucose oxidase and l-arginine, while conjugated monomer and N-doping guaranteed bright fluorescence and relatively strong interactions between loaded cargos. Well-designed size allowed easy cell uptake of drug-loaded COFs, which finally resulted in a highly efficient starvation therapy by consuming large amounts of glucose in cancer cells. H₂O₂, the byproduct during glucose consumption, was made full use of oxidizing l-arginine to generate toxic NO. This constructed combined starvation and gas therapy and exhibited emerging antimigration performance. Both in vitro and in vivo experiments confirmed an excellent cancer therapeutic effect than a single therapy, and the novel therapeutic platform showed good biocompatibility. Detailed mechanism study demonstrated that cell apoptosis and lysosomal damage contributed most to the synergistic treatment. Our study developed a new strategy to synthesize highly conjugated COFs with fluorescence and reported the potential applications in cancer therapy.

Red fluorescent AIEgens based multifunctional nonviral gene vectors for the efficient combination of gene therapy and photodynamic therapy in anti-cancer

Precise molecular engineering of AIEgens-based cationic delivery systems for high transfection efficiency (TE) and effective photodynamic therapy (PDT) holds a huge potential for cancer treatment. Herein, three amphiphiles (DT-C_6/8/12-M) consisting of di(triazole-[12]aneN₃) (M) and 1,1-dicyano-2-phenyl-2-(4-diphenylamino)phenyl-ethylene (DT) units have been developed to achieve luminescent tracking, efficient TE, and effective PDT in vitro and in vivo. These compounds exhibited strong aggregated induced emission (AIE) at 630 nm and mega Stokes shifts of up to 160 nm. They were able to bind DNA into nanoparticles with suitable sizes, positive surface potential, and good biocompatibility in the presence of DOPE. Among them, vector DT-C₁₂-M/DOPE with n-dodecyl linker achieved a transfection efficiency as high as 42.3 folds that of Lipo2000 in PC-3 cell lines. DT-C₁₂-M/DOPE exhibited the capability of successful endo/lysosomal escape and rapid nuclear delivery of pDNA, and the gene delivery process was clearly monitored via confocal laser scanning microscopy. Moreover, efficient reactive oxygen species (ROS) generation by DT-C₁₂-M upon light irradiation led to effective PDT in vitro . We further show that combination of p53 gene therapy and PDT dramatically enhanced cancer therapeutic outcome in vivo. This "three birds, one stone" strategy offers a novel and promising approach for real-time tracking of gene delivery and better cancer treatment.

Contact-Free Remote Manipulation of Hydrogel Properties Using Light-Triggerable Nanoparticles: A Materials Science Perspective for Biomedical Applications

Considerable progress has been made in synthesizing "intelligent", biodegradable hydrogels that undergo rapid changes in physicochemical properties once exposed to external stimuli. These advantageous properties of stimulus-triggered materials make them highly appealing to diverse biomedical applications. Of late, research on the incorporation of light-triggered nanoparticles (NPs) into polymeric hydrogel networks has gained momentum due to their ability to remotely tune hydrogel properties using facile, contact-free approaches, such as adjustment of wavelength and intensity of light source. These multi-functional NPs, in combination with tissue-mimicking hydrogels, are increasingly being used for on-demand drug release, preparing diagnostic kits, and fabricating smart scaffolds. Here, the authors discuss the atomic behavior of different NPs in the presence of light, and critically review the mechanisms by which NPs convert light stimuli into heat energy. Then, they explain how these NPs impact the mechanical properties and rheological behavior of NPs-impregnated hydrogels. Understanding the rheological behavior of nanocomposite hydrogels using different sophisticated strategies, including computer-assisted machine learning, is critical for designing the next generation of drug delivery systems. Next, they highlight the salient strategies that have been used to apply light-induced nanocomposites for diverse biomedical applications and provide an outlook for the further improvement of these NPs-driven light-responsive hydrogels.

Synthesis of Anionic Nanogels for Selective and Efficient Enzyme Encapsulation

Polyelectrolyte nanogels containing cross-linked ionic polymer networks feature both soft environment and intrinsic charges which are of great potential for enzyme encapsulation. In this work, well-defined poly(acrylic acid) (PAA) nanogels have been synthesized based on a facile strategy, namely, electrostatic assembly directed polymerization (EADP). Specifically, AA monomers are polymerized together with a cross-linker in the presence of a cationic-neutral diblock copolymer as the template. Effects of control factors including pH, salt concentration, and cross-linking degree have been investigated systematically, based on which the optimal preparation of PAA nanogels has been established. The obtained nanogel features not only compatible pocket for safely loading enzymes without disturbing their structures, but also abundant negative charges which enable selective and efficient encapsulation of cationic enzymes. The loading capacities of PAA nanogels for cytochrome (cyt c) and lysozyme are 100 and 125 μg/mg (enzyme/nanogel), respectively. More notably, the PAA network seems to modulate a favorable microenvironment for cyt c and induces 2-fold enhanced activity for the encapsulated enzymes, as indicated by the steady-state kinetic assay. Our study reveals the control factors of EADP for optimal synthesis of anionic nanogels and validates their distinctive advances with respect to efficient loading and activation of cationic enzymes.

Light-Triggered Polymersome-Based Anticancer Therapeutics Delivery

Polymersomes are biomimetic cell membrane-like model structures that are self-assembled stepwise from amphiphilic copolymers. These polymeric (nano)carriers have gained the scientific community's attention due to their biocompatibility, versatility, and higher stability than liposomes. Their tunable properties, such as composition, size, shape, and surface functional groups, extend encapsulation possibilities to either hydrophilic or hydrophobic cargoes (or both) and their site-specific delivery. Besides, polymersomes can disassemble in response to different stimuli, including light, for controlling the "on-demand" release of cargo that may also respond to light as photosensitizers and plasmonic nanostructures. Thus, polymersomes can be spatiotemporally stimulated by light of a wide wavelength range, whose exogenous response may activate light-stimulable moieties, enhance the drug efficacy, decrease side effects, and, thus, be broadly employed in photoinduced therapy. This review describes current light-responsive polymersomes evaluated for anticancer therapy. It includes light-activable moieties' features and polymersomes' composition and release behavior, focusing on recent advances and applications in cancer therapy, current trends, and photosensitive polymersomes' perspectives.

Rational Polyelectrolyte Design Enables Multifunctional Polyion Complex Vesicles

Polyion complex (PIC) vesicles prepared by polyelectrolyte assembly have attracted extensive attention as distinctive carriers and nanoreactors, particularly for biological cargoes. However, the constrained regulation of their structure and functionality at this stage hinder the application of PIC vesicles. Herein, we design a new asymmetric assembly system, namely cationic-neutral-cationic triblock copolymer co-assembly with a supramolecular ionic coordination polymer. The former creates poly(ethylene oxide) (PEO) loops upon complexation, which are favorable for vesicle fabrication, while the coordination polyelectrolyte composed of metal ions and a dipicolinic acid (DPA)-based bis-ligand features well-defined functionalities depending on the incorporated metal ions. Thus, the rational combination allows controlled fabrication of PIC vesicles with a modulated structure and functionalities. Moreover, the encapsulation and release of hydrophilic dextran based on different PIC vesicles has been realized. Our design integrates the advantages of both triblock and coordination polymers, and therefore demonstrates a novel strategy for harmonious regulation of the structure and functionality of PIC vesicles. The revealed findings and achieved properties shall be inspirational for developing functional PIC vesicles and boosting their applications towards demand encapsulation and delivery.

Enhanced tumour penetration and prolonged circulation in blood of polyzwitterion-drug conjugates with cell-membrane affinity

Effective anticancer nanomedicines need to exhibit prolonged circulation in blood, to extravasate and accumulate in tumours, and to be taken up by tumour cells. These contrasting criteria for persistent circulation and cell-membrane affinity have often led to complex nanoparticle designs with hampered clinical translatability. Here, we show that conjugates of small-molecule anticancer drugs with the polyzwitterion poly(2-(N-oxide-N,N-diethylamino)ethyl methacrylate) have long blood-circulation half-lives and bind reversibly to cell membranes, owing to the negligible interaction of the polyzwitterion with proteins and its weak interaction with phospholipids. Adsorption of the polyzwitterion-drug conjugates to tumour endothelial cells and then to cancer cells favoured their transcytosis-mediated extravasation into tumour interstitium and infiltration into tumours, and led to the eradication of large tumours and patient-derived tumour xenografts in mice. The simplicity and potency of the polyzwitterion-drug conjugates should facilitate the design of translational anticancer nanomedicines.

Ruthenium(II) complexes coordinated to graphitic carbon nitride: Oxygen self-sufficient photosensitizers which produce multiple ROS for photodynamic therapy in hypoxia

The photodynamic therapy (PDT) of cancer is limited by tumor hypoxia as PDT efficiency depends on O₂ concentration. A novel oxygen self-sufficient photosensitizer (Ru-g-C₃N₄) was therefore designed and synthesized via a facile one-pot method in order to overcome tumor hypoxia-induced PDT resistance. The photosensitizer is based on [Ru(bpy)₂]²⁺ coordinated to g-C₃N₄ nanosheets by Ru-N bonding. Compared to pure g-C₃N₄, the resulting nanosheets exhibit increased water solubility, stronger visible light absorption, and enhanced biocompatibility. Once Ru-g-C₃N₄ is taken up by hypoxic tumor cells and exposed to visible light, the nanosheets not only catalyze the decomposition of H₂O₂ and H₂O to generate O₂, but also catalyze H₂O₂ and O₂ concurrently to produce multiple ROS (^•OH, ^•O₂^-, and ¹O₂). In addition, Ru-g-C₃N₄ affords luminescence imaging, while continuously generating O₂ to alleviate hypoxia greatly improving PDT efficacy. To the best of our knowledge, this oxygen self-sufficient photosensitizer produced via grafting a metal complex onto g-C₃N₄ is the first of its type to be reported.

Metallic Oxide-Induced Self-Assembly of Block Copolymers to Form Polymeric Hybrid Micelles with Tunable Stability for Tumor Microenvironment-Responsive Drug Delivery

Since block copolymers are able to self-assemble into various polymeric architectures, it is intriguing to explore a unique self-assembly strategy for polymers. Two different metallic oxides [manganese dioxide (MnO2) and zinc oxide (ZnO)] are displayed herein to demonstrate this self-assembly mechanism of polymers. In situ generation of metallic oxides induces self-assembly of block copolymers to form polymeric hybrid micelles with tunable stability in aqueous solutions. These final ZnO-cross-linked polymeric micelles exhibited a high drug loading capacity of 0.41 mg mg-1 toward doxorubicin (DOX), whereas DOX-loaded ZnO-cross-linked polymeric micelles could be broken down into Zn2+ and polymer scraps, which facilitated drug release in tumor microenvironments. Both in vitro and in vivo investigations showed that the drug-loaded ZnO-cross-linked polymeric micelles effectively suppressed tumor growth. Accordingly, the present study demonstrates a novel strategy of polymer self-assembly for fabricating polymeric architectures that can potentially provide insight for developing other polymeric architectures.

Versatile gadolinium(III)-phthalocyaninate photoagent for MR/PA imaging-guided parallel photocavitation and photodynamic oxidation at single-laser irradiation

Current light-mediated photodynamic therapy (PDT) is far underutilized in clinical cancer treatment due to its low pharmacological effect. We herein proposed a new gadolinium(III)-phthalocyanine (GdPc)-enabled phototherapeutics, photoacoustic/dynamic therapy (PADT), towards in vivo solid tumors via parallel-produced photocavitation and photodynamic oxidation with excitation by a single pulsed laser. We demonstrated that pulsed irradiation of GdPc could simultaneously produce an intense acoustic effect and a high-level ¹O₂ quantum yield to afford mitochondrial damage and initiate programmed cell death. Under the guidance of magnetic resonance/photoacoustic dual-modal imaging, the mechanical oxygen-independent destruction of acoustic cavitation and the chemical damage of ¹O₂ were validated to afford combinatorial inhibition of tumors under either normal or hypoxic conditions after the agent delivered into the cancer cells by a pH-sensitive nanomicelle. The single-laser initiated PADT using GdPc as a versatile photoagent maximizes the use of light energy to minimize the dose requirement of oxygen and agent towards high therapeutic efficacy, surpassing dramatically over conventional PDT.

All-Peptide-Based Polyion Complex Vesicles: Facile Preparation and Encapsulation of the Protein in Active Form

The polyion complex vesicle (PICsome) is a promising platform for bioactive molecule delivery as well as nanoreactor systems. In addition to anionic and cationic charged blocks, a hydrophilic poly(ethylene glycol) (PEG) block is mostly employed for PICsome formation; however, the long-term safety of the PEG component in vivo is yet to be clarified. In this study, we developed novel PEG-free PICsome comprising all peptide components. Instead of the PEG block, we selected the sarcosine (Sar) oligomer as a hydrophilic block and fused it with anionic oligo(l-glutamic acid). Mixing the Sar-containing anionic peptide with cationic oligo(l-lysine) resulted in the formation of stable vesicles. The peptide-based PICsome was able to encapsulate a model protein in its hollow structure. After modification of the surface with a cell-penetrating peptide, the protein-encapsulated PICsome was successfully delivered into plant cells, indicating its promised for application as a biocompatible carrier for protein delivery.

Light-Responsive Micelles Loaded With Doxorubicin for Osteosarcoma Suppression

The enhancement of tumor targeting and cellular uptake of drugs are significant factors in maximizing anticancer therapy and minimizing the side effects of chemotherapeutic drugs. A key challenge remains to explore stimulus-responsive polymeric nanoparticles to achieve efficient drug delivery. In this study, doxorubicin conjugated polymer (Poly-Dox) with light-responsiveness was synthesized, which can self-assemble to form polymeric micelles (Poly-Dox-M) in water. As an inert structure, the polyethylene glycol (PEG) can shield the adsorption of protein and avoid becoming a protein crown in the blood circulation, improving the tumor targeting of drugs and reducing the cardiotoxicity of doxorubicin (Dox). Besides, after ultraviolet irradiation, the amide bond connecting Dox with PEG can be broken, which induced the responsive detachment of PEG and enhanced cellular uptake of Dox. Notably, the results of immunohistochemistry in vivo showed that Poly-Dox-M had no significant damage to normal organs. Meanwhile, they showed efficient tumor-suppressive effects. This nano-delivery system with the light-responsive feature might hold great promises for the targeted therapy for osteosarcoma.

Tumor Microenvironment-Specific Chemical Internalization for Enhanced Gene Therapy of Metastatic Breast Cancer

Benefiting from treating diseases at the genetic level, gene therapy has been considered a new revolution in the biomedical field. However, the extracellular and intracellular barriers during gene transport such as enzymatic degradation and endo-/lysosomal sequestration significantly compromise the therapeutic efficacy. Though photochemical internalization (PCI) has emerged as a promising approach for causing endo-/lysosomal leakage with translocation of the internalized molecules into the cytosol, its effect is still unsatisfactory due to the insufficient light penetration depth. Here, we develop tumor microenvironment-specific enhanced gene delivery by means of ROS generated from the in situ cascaded catalytic reactions in tumors involving GOx-mediated redox reaction and Mn2+-mediated Fenton-like reaction. The efficient enzymatic protection and successful endo-/lysosomal escape of cargo gene complexes have been demonstrated. Moreover, anti-Twist siRNA-loaded G@MMSNs-P exhibit tumor-specific biodegradation, excellent T1-weighted MR imaging, and significant inhibitory effects against breast cancer growth and pulmonary metastasis.

Tumor hypoxia-activated combinatorial nanomedicine triggers systemic antitumor immunity to effectively eradicate advanced breast cancer

Hypoxia is a major obstacle towards successful cancer treatment, due to the hypoxia-mediated resistance to radiotherapy and chemotherapy, as well as immunosuppression. Therefore, engineering hypoxia-sensitive cytotoxic and immunogenic nanomedicines would promote the therapeutic efficacy. In this study, we developed novel tumor-targeted polymeric micelles sensing hypoxia in tumors to activate strong cytotoxicity and immunogenic responses for effectively eradicating advanced breast cancer. The hypoxia-activatable polymeric micelles could efficiently deliver anticancer drugs and photosensitizers into cancer cells, to trigger synergistic cytotoxicity and immunogenic cell death through chemotherapy and photodynamic therapy (PDT)/photothermal therapy (PTT). The long-circulating micelles efficiently delivered drugs to triple negative 4T1 breast tumors for accurate tumor diagnosis by photoacoustic imaging (PA), and effectively eliminating primary tumors without recurrence, including hypoxic 4T1 tumors. In addition, the micelle-based eradication of primary tumors could elicit robust systemic immune responses to inhibit tumor recurrence and significantly suppress distant 4T1 tumors and lung metastasis by combining with CpG and aCTLA4. These results indicate the high performance of our innovative multifunctional micelles for synergistic therapy against tumor malignancy, bringing opportunity for effectively dealing with disseminated and metastatic tumors.

Improvement of Gold Nanorods in Photothermal Therapy: Recent Progress and Perspective

Cancer is a life-threatening disease, and there is a significant need for novel technologies to treat cancer with an effective outcome and low toxicity. Photothermal therapy (PTT) is a noninvasive therapeutic tool that transports nanomaterials into tumors, absorbing light energy and converting it into heat, thus killing tumor cells. Gold nanorods (GNRs) have attracted widespread attention in recent years due to their unique optical and electronic properties and potential applications in biological imaging, molecular detection, and drug delivery, especially in the PTT of cancer and other diseases. This review summarizes the recent progress in the synthesis methods and surface functionalization of GNRs for PTT. The current major synthetic methods of GNRs and recently improved measures to reduce toxicity, increase yield, and control particle size and shape are first introduced, followed by various surface functionalization approaches to construct a controlled drug release system, increase cell uptake, and improve pharmacokinetics and tumor-targeting effect, thus enhancing the photothermal effect of killing the tumor. Finally, a brief outlook for the future development of GNRs modification and functionalization in PTT is proposed.

Near-Infrared Photo-controlled Permeability of a Biomimetic Polymersome with Sustained Drug Release and Efficient Tumor Therapy

Synthetic polymersomes have structure similarity to bio-vesicles and could disassemble in response to stimuli for "on-demand" release of encapsulated cargos. Though widely applied as a drug delivery carrier, the burst release mode with structure complete destruction is usually taken for most responsive polymersomes, which would shorten the effective drug reaction time and impair the therapeutic effect. Inspired by the cell organelles' communication mode via regulating membrane permeability for transportation control, we highlight here a biomimetic polymersome with sustained drug release over a specific period of time via near-infrared (NIR) pre-activation. The polymersome is prepared by the self-assembling amphiphilic diblock copolymer P(OEGMA-co-EoS)-b-PNBOC and encapsulates the hypoxia-activated prodrug AQ4N and upconversion nanoparticle (PEG-UCNP) in its hydrophilic centric cavity. Thirty minutes of NIR pre-activation triggers cross-linking of NBOC and converts the permeability of the polymersome with sustained AQ4N release until 24 h after the NIR pre-activation. The photosensitizer EoS is activated and aggravates environmental hypoxic conditions during a sustained drug release period to boost the AQ4N therapeutic effect. The combination of sustained drug release with concurrent hypoxia intensification results in a highly efficient tumor therapeutic effect both intracellularly and in vivo. This biomimetic polymersome will provide an effective and universal tumor therapeutic approach.

Lysosome-targeted photodynamic treatment induces primary keratinocyte differentiation

Photodynamic therapy is an attractive technique for various skin tumors and non-cancerous skin lesions. However, while the aim of photodynamic therapy is to target and damage only the malignant cells, it unavoidably affects some of the healthy cells surrounding the tumor as well. However, data on the effects of PDT to normal cells are scarce, and the characterization of the pathways activated after the photodamage of normal cells may help to improve clinical photodynamic therapy. In our study, primary human epidermal keratinocytes were used to evaluate photodynamic treatment effects of photosensitizers with different subcellular localization. We compared the response of keratinocytes to lysosomal photodamage induced by phthalocyanines, aluminum phthalocyanine disulfonate (AlPcS_2a) or aluminum phthalocyanine tetrasulfonate (AlPcS₄), and cellular membrane photodamage by m-tetra(3-hydroxyphenyl)-chlorin (mTHPC). Our data showed that mTHPC-PDT promoted autophagic flux, whereas lysosomal photodamage induced by aluminum phthalocyanines evoked differentiation and apoptosis. Photodamage by AlPcS_2a, which is targeted to lysosomal membranes, induced keratinocyte differentiation and apoptosis more efficiently than AlPcS₄, which is targeted to lysosomal lumen. Computational analysis of the interplay between these molecular pathways revealed that keratin 10 is the coordinating molecular hub of primary keratinocyte differentiation, apoptosis and autophagy.

Optimal synthesis of polyelectrolyte nanogels by electrostatic assembly directed polymerization for dye loading and release

Polyelectrolyte (PE) nanogels which combine features of nanogels and polyelectrolytes have attracted significant attention as outstanding nano-carriers. However, and crucially, any large-scale application of PE nanogels can only materialize when an efficient production method is available. We recently developed such a robust approach, namely Electrostatic Assembly Directed Polymerization (EADP), in which ionic monomers are polymerized together with cross-linker in the presence of a polyion-neutral diblock copolymer as template. Although EADP achieves efficient and scalable preparation of diverse PE nanogels, the essential factors for the optimal and controlled synthesis of nanogels have remained elusive. In this article, we investigate systematically the effects of pH, salt concentration, and cross-linker fractions on the formation and properties of a PDMAEMA nanogel prepared with PAA-b-PEO as the template. We find that the electrostatic interaction between the building blocks is crucial to obtain assembly-controlled polymerization, and we establish preferred pH, salt concentration and cross-linker fractions. The obtained PDMAEMA nanogel exhibits dual-responses to pH and salt, which allow manipulation of the positive charges of the nanogels for selective loading and controlled release of anionic substances; we demonstrate this with an anionic dye. The study presented here fully addresses the process parameters of EADP regarding optimal and controlled preparation of PE nanogels, which should allow exploration of their potential vis-a-vis a variety of applications.

Photoacoustic Cavitation-Ignited Reactive Oxygen Species to Amplify Peroxynitrite Burst by Photosensitization-Free Polymeric Nanocapsules

Photoacoustic (PA) technology can transform light energy into acoustic wave, which can be used for either imaging or therapy that depends on the power density of pulsed laser. Here, we report photosensitizer-free polymeric nanocapsules loaded with nitric oxide (NO) donors, namely NO-NCPs, formulated from NIR light-absorbable amphiphilic polymers and a NO-releasing donor, DETA NONOate. Controlled NO release and nanocapsule dissociation are achieved in acidic lysosomes of cancer cells. More importantly, upon pulsed laser irradiation, the PA cavitation can excite water to generate significant reactive oxygen species (ROS) such as superoxide radical (O₂ ^.- ), which further spontaneously reacts with the in situ released NO to burst highly cytotoxic peroxynitrite (ONOO^- ) in cancer cells. The resultant ONOO^- generation greatly promotes mitochondrial damage and DNA fragmentation to initiate programmed cancer cell death. Apart from PA imaging, PA cavitation can intrinsically amplify reactive species via photosensitization-free materials for promising disease theranostics.

Heavy-Atom-Modulated Supramolecular Assembly Increases Antitumor Potency against Malignant Breast Tumors via Tunable Cooperativity

Triple-negative breast cancer (TNBC) remains with highest incidence and mortality rates among females, and a critical bottleneck lies in rationally establishing potent therapeutics against TNBC. Here, the self-assembled micellar nanoarchitecture of heavy-atom-modulated supramolecules with efficient cytoplasmic translocation and tunable photoconversion is shown, for potent suppression against primary, metastatic, and recurrent TNBC. Multi-iodinated boron dipyrromethene micelles yield tunable photoconversion into singlet oxygen and a thermal effect, together with deep penetration and subsequent cytoplasmic translocation at the tumor. Tetra-iodinated boron dipyrromethene micelles (4-IBMs) particularly show a distinctly enhanced cooperativity of antitumor efficiency through considerable expressions of apoptotic proteins, potently suppressing subcutaneous, and orthotopic TNBC models, together with reduced oxygen dependence. Furthermore, 4-IBMs yield preferable anti-metastatic and anti-recurrent efficacies through the inhibition of metastasis-relevant proteins, distinct immunogenic cell death, and re-education of M2 macrophages into tumoricidal M1 phenotype as compared to chemotherapy and surgical resection. These results offer insights into the cooperativity of supramolecular nanoarchitectures for potent phototherapy against TNBC.

A PEGylated photosensitizer-core pH-responsive polymeric nanocarrier for imaging-guided combination chemotherapy and photodynamic therapy

A novel chemo-photodynamic combined therapeutic self-assembly polymeric platform (MPEG-Hyd-Br₂-BODIPY) was constructed which can encapsulate DOX and exhibited an accelerated release rate with decreasing pH value which results in considerable time/dose-dependent cytotoxicity.

A zwitterionic red-emitting water-soluble conjugated polymer with high resistance to nonspecific binding for two-photon cell imaging and good singlet oxygen production capability

A zwitterionic red-emitting water-soluble conjugated polymer exhibited better two-photon cell imaging and singlet oxygen production capability than its cationic analogue.

Efficient Synthesis of Stable Polyelectrolyte Complex Nanoparticles by Electrostatic Assembly Directed Polymerization

Polyelectrolyte complex nanoparticles with integrated advances of coacervate complexes and nanomaterials have attracted considerable attention as soft templates and functional nano-carriers. Herein, a facile and robust strategy, namely electrostatic assembly directed polymerization (EADP), for efficient and scalable preparation of stable coacervate nanoparticles is presented. With homo-polyelectrolyte PAA (polyacrylic acid) as template and out of charge stoichiometry, the cationic monomers are polymerized together with cross-linkers, which creates coacervate nanoparticles featuring high stability against salt through one-pot synthesis. The particle size can be tuned by varying the cross-linker amount and salt concentrations during the polymerization and the composition of nanoparticles, as well as the corresponding properties can be regulated by combining different charged blocks from both strong and weak ionic monomers. The strategy can tolerate both high monomer concentrations and increased volume of up to l L, which is favorable for scaled-up preparations. Moreover, the coacervate nanoparticles can be freeze-dried to produce a product in powder form, which can be redispersed without any effect on the particle size and size distribution. Finally, the obtained nanoparticles loaded with enzyme and Au nanoparticles exhibit enhanced catalytic performance, demonstrating a great potential for exploring various applications of coacervate particles as soft and functional nano-carriers.

Chemo-physical Strategies to Advance the in Vivo Functionality of Targeted Nanomedicine: The Next Generation

The past few decades have witnessed an evolution of nanomedicine from biologically inert entities to more smart systems, aimed at advancing in vivo functionality. However, we should recognize that most systems still rely on reasonable explanation-including some over-explanation-rather than definitive evidence, which is a watershed radically determining the speed and extent of advancing nanomedicine. Probing nano-bio interactions and desirable functionality at the tissue, cellular, and molecular levels is most frequently overlooked. Progress toward answering these questions will provide instructive insight guiding more effective chemo-physical strategies. Thus, in the next generation, we argue that much effort should be made to provide definitive evidence for proof-of-mechanism, in lieu of creating many new and complicated systems for similar proof-of-concept.

A Nanomedicine Fabricated from Gold Nanoparticles-Decorated Metal-Organic Framework for Cascade Chemo/Chemodynamic Cancer Therapy

The incorporation of new modalities into chemotherapy greatly enhances the anticancer efficacy combining the merits of each treatment, showing promising potentials in clinical translations. Herein, a hybrid nanomedicine (Au/FeMOF@CPT NPs) is fabricated using metal-organic framework (MOF) nanoparticles and gold nanoparticles (Au NPs) as building blocks for cancer chemo/chemodynamic therapy. MOF NPs are used as vehicles to encapsulate camptothecin (CPT), and the hybridization by Au NPs greatly improves the stability of the nanomedicine in a physiological environment. Triggered by the high concentration of phosphate inside the cancer cells, Au/FeMOF@CPT NPs effectively collapse after internalization, resulting in the complete drug release and activation of the cascade catalytic reactions. The intracellular glucose can be oxidized by Au NPs to produce hydrogen dioxide, which is further utilized as chemical fuel for the Fenton reaction, thus realizing the synergistic anticancer efficacy. Benefitting from the enhanced permeability and retention effect and sophisticated fabrications, the blood circulation time and tumor accumulation of Au/FeMOF@CPT NPs are significantly increased. In vivo results demonstrate that the combination of chemotherapy and chemodynamic therapy effectively suppresses the tumor growth, meantime the systemic toxicity of this nanomedicine is greatly avoided.

Polythiophenes with Cationic Phosphonium Groups as Vectors for Imaging, siRNA Delivery, and Photodynamic Therapy

In this work, we exploit the versatile function of cationic phosphonium-conjugated polythiophenes to develop multifunctional platforms for imaging and combined therapy (siRNA delivery and photodynamic therapy). The photophysical properties (absorption, emission and light-induced generation of singlet oxygen) of these cationic polythiophenes were found to be sensitive to molecular weight. Upon light irradiation, low molecular weight cationic polythiophenes were able to light-sensitize surrounding oxygen into reactive oxygen species (ROS) while the highest were not due to its aggregation in aqueous media. These polymers are also fluorescent, allowing one to visualize their intracellular location through confocal microscopy. The most promising polymers were then used as vectors for siRNA delivery. Due to their cationic and amphipathic features, these polymers were found to effectively self-assemble with siRNA targeting the luciferase gene and deliver it in MDA-MB-231 cancer cells expressing luciferase, leading to 30-50% of the gene-silencing effect. In parallel, the photodynamic therapy (PDT) activity of these cationic polymers was restored after siRNA delivery, demonstrating their potential for combined PDT and gene therapy.

Regulating vesicle bilayer permeability and selectivity via stimuli-triggered polymersome-to-PICsome transition

Compared to liposomes, polymersomes of block copolymers (BCPs) possess enhanced stability, along with compromised bilayer permeability. Though polyion complex vesicles (PICsomes) from oppositely charged block polyelectrolytes possess semipermeable bilayers, they are unstable towards physiologically relevant ionic strength and temperature; moreover, permselectivity tuning of PICsomes has remained a challenge. Starting from a single component diblock or triblock precursor, we solve this dilemma by stimuli-triggered chemical reactions within pre-organized BCP vesicles, actuating in situ polymersome-to-PICsome transition and achieving molecular size-selective cargo release at tunable rates. UV light and reductive milieu were utilized to trigger carboxyl decaging and generate ion pairs within hydrophobic polymersome bilayers containing tertiary amines. Contrary to conventional PICsomes, in situ generated ones are highly stable towards extreme pH range (pH 2-12), ionic strength (~3 M NaCl), and elevated temperature (70 °C) due to multivalent ion-pair interactions at high local concentration and cooperative hydrogen bonding interactions of pre-organized carbamate linkages.

Stimuli-responsive nanocarriers for drug delivery, tumor imaging, therapy and theranostics

In recent years, much progress has been motivated in stimuli-responsive nanocarriers, which could response to the intrinsic physicochemical and pathological factors in diseased regions to increase the specificity of drug delivery. Currently, numerous nanocarriers have been engineered with physicochemical changes in responding to external stimuli, such as ultrasound, thermal, light and magnetic field, as well as internal stimuli, including pH, redox potential, hypoxia and enzyme, etc. Nanocarriers could respond to stimuli in tumor microenvironments or inside cancer cells for on-demanded drug delivery and accumulation, controlled drug release, activation of bioactive compounds, probes and targeting ligands, as well as size, charge and conformation conversion, etc., leading to sensing and signaling, overcoming multidrug resistance, accurate diagnosis and precision therapy. This review has summarized the general strategies of developing stimuli-responsive nanocarriers and recent advances, presented their applications in drug delivery, tumor imaging, therapy and theranostics, illustrated the progress of clinical translation and made prospects.

Polymer Nanocontainers for Intracellular Delivery

Carriers for intracellular delivery are required to overcome limitations of therapeutic agents such as low specificity, systemic toxicity, high clearance rate, and low therapeutic index. Nanocontainers comprised of an aqueous core and a polymer shell have received increasing attention because they readily combine stimuli response to improve intracellular payload release and surface modification to enhance selectivity towards the desired region of action. This Minireview summarizes the design and properties of polymer nanocontainers for intracellular delivery, classified according to the polymer architecture.

Photochemical Internalization for Intracellular Drug Delivery. From Basic Mechanisms to Clinical Research

Photochemical internalisation (PCI) is a unique intervention which involves the release of endocytosed macromolecules into the cytoplasmic matrix. PCI is based on the use of photosensitizers placed in endocytic vesicles that, following light activation, lead to rupture of the endocytic vesicles and the release of the macromolecules into the cytoplasmic matrix. This technology has been shown to improve the biological activity of a number of macromolecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), gene-encoding plasmids, adenovirus and oligonucleotides and certain chemotherapeutics, such as bleomycin. This new intervention has also been found appealing for intracellular delivery of drugs incorporated into nanocarriers and for cancer vaccination. PCI is currently being evaluated in clinical trials. Data from the first-in-human phase I clinical trial as well as an update on the development of the PCI technology towards clinical practice is presented here.

A Metal-Polyphenol-Coordinated Nanomedicine for Synergistic Cascade Cancer Chemotherapy and Chemodynamic Therapy

The clinical application of chemotherapy is impeded by the unsatisfactory efficacy and severe side effects. Chemodynamic therapy (CDT) has emerged as an efficient strategy for cancer treatment utilizing Fenton chemistry to destroy cancer cells by converting endogenous H₂ O₂ into highly toxic reactive oxygen species. Apart from the chemotherapeutic effect, cisplatin is able to act as an artificial enzyme to produce H₂ O₂ for CDT through cascade reactions, thus remarkably improving the anti-tumor outcomes. Herein, an organic theranostic nanomedicine (PTCG NPs) is constructed with high loading capability using epigallocatechin-3-gallate (EGCG), phenolic platinum(IV) prodrug (Pt-OH), and polyphenol modified block copolymer (PEG-b-PPOH) as the building blocks. The high stability of PTCG NPs during circulation stems from their strong metal-polyphenol coordination interactions, and efficient drug release is realized after cellular internalization. The activated cisplatin elevates the intracellular H₂ O₂ level through cascade reactions. This is further utilized to produce highly toxic reactive oxygen species catalyzed by an iron-based Fenton reaction. In vitro and in vivo investigations demonstrate that the combination of chemotherapy and chemodynamic therapy achieves excellent anticancer efficacy. Meanwhile, systemic toxicity faced by platinum-based drugs is avoided through this nanoformulation. This work provides a promising strategy to develop advanced nanomedicine for cascade cancer therapy.

Rational design of block copolymer self-assemblies in photodynamic therapy

Photodynamic therapy is a technique already used in ophthalmology or oncology. It is based on the local production of reactive oxygen species through an energy transfer from an excited photosensitizer to oxygen present in the biological tissue. This review first presents an update, mainly covering the last five years, regarding the block copolymers used as nanovectors for the delivery of the photosensitizer. In particular, we describe the chemical nature and structure of the block copolymers showing a very large range of existing systems, spanning from natural polymers such as proteins or polysaccharides to synthetic ones such as polyesters or polyacrylates. A second part focuses on important parameters for their design and the improvement of their efficiency. Finally, particular attention has been paid to the question of nanocarrier internalization and interaction with membranes (both biomimetic and cellular), and the importance of intracellular targeting has been addressed.

Catalytic rhodium (Rh)-based (mesoporous polydopamine) MPDA nanoparticles with enhanced phototherapeutic efficiency for overcoming tumor hypoxia

Rh NPs/Ce6 loaded mesoporous polydopamine (Ce6-Rh@MPDA) nanoparticles were developed to achieve photoacoustic/fluorescence imaging-guided photothermal and photodynamic therapy to eliminate tumors and improve hypoxia in tumor microenvironments.

Upconversion superballs for programmable photoactivation of therapeutics

Upconversion nanoparticles (UCNPs) are the preferred choice for deep-tissue photoactivation, owing to their unique capability of converting deep tissue-penetrating near-infrared light to UV/visible light for photoactivation. Programmed photoactivation of multiple molecules is critical for controlling many biological processes. However, syntheses of such UCNPs require epitaxial growth of multiple shells on the core nanocrystals and are highly complex/time-consuming. To overcome this bottleneck, we have modularly assembled two distinct UCNPs which can individually be excited by 980/808 nm light, but not both. These orthogonal photoactivable UCNPs superballs are used for programmed photoactivation of multiple therapeutic processes for enhanced efficacy. These include sequential activation of endosomal escape through photochemical-internalization for enhanced cellular uptake, followed by photocontrolled gene knockdown of superoxide dismutase-1 to increase sensitivity to reactive oxygen species and finally, photodynamic therapy under these favorable conditions. Such programmed activation translated to significantly higher therapeutic efficacy in vitro and in vivo in comparison to conventional, non-programmed activation.