Gradient Redox-Responsive and Two-Stage Rocket-Mimetic Drug Delivery System for Improved Tumor Accumulation and Safe Chemotherapy

Tailored design of NHS-SS-NHS cross-linked chitosan nano-hydrogels for enhanced anti-tumor efficacy by GSH-responsive drug release

The traditional chemotherapeutic agents' disadvantages such as high toxicity, untargeting and poor water solubility lead to disappointing chemotherapy effects, which restricts its clinical application. In this work, novel size-appropriate and glutathione (GSH)-responsive nano-hydrogels were successfully prepared via the active ester method between chitosan (containing -NH2) and cross-linker (containing NHS). Especially, the cross-linker was elaborately designed to possess a disulfide linkage (SS) as well as two terminal NHS groups, namely NHS-SS-NHS. These functionalities endowed chitosan-based cross-linked scaffolds with capabilities for drug loading and delivery, as well as a GSH-responsive mechanism for drug release. The prepared nano-hydrogels demonstrated excellent performance applicable morphology, excellent drug loading efficiency (∼22.5%), suitable size (∼100 nm) and long-term stability. The prepared nano-hydrogels released over 80% doxorubicin (DOX) after incubation in 10 mM GSH while a minimal DOX release less than 25% was tested in normal physiological buffer (pH = 7.4). The unloaded nano-hydrogels did not show any apparent cytotoxicity to A 549 cells. In contrast, DOX-loaded nano-hydrogels exhibited marked anti-tumor activity against A 549 cells, especially in high GSH environment. Finally, through fluorescent imaging and flow cytometry analysis, fluorescein isothiocyanate-labeled nano-hydrogels show obvious specific binding to the GSH high-expressing A549 cells and nonspecific binding to the GSH low-expressing A549 cells. Therefore, with this cross-linking approach, our present finding suggests that cross-linked chitosan nano-hydrogel drug carrier improves the anti-tumor effect of the A 549 cells and may serve as a potential injectable delivery carrier.

Tumor microenvironment-responsive degradable silica nanoparticles: design principles and precision theranostic applications

Silica nanoparticles have emerged as promising candidates in the field of nanomedicine due to their remarkable versatility and customizable properties. However, concerns about their potential toxicity in healthy tissues and organs have hindered their widespread clinical translation. To address this challenge, significant attention has been directed toward a specific subset of silica nanoparticles, namely degradable silica nanoparticles, primarily because of their excellent biocompatibility and responsive biodegradability. In this review, we provide a comprehensive understanding of degradable silica nanoparticles, categorizing them into two distinct groups: inorganic species-doped and organic moiety-doped silica nanoparticles based on their framework components. Next, the recent progress of tumor microenvironment (TME)-responsive degradable silica nanoparticles for precision theranostic applications is summarized in detail. Finally, current bottlenecks and future opportunities of theranostic nanomedicines based on degradable silica nanoparticles in clinical applications are also outlined and discussed. The aim of this comprehensive review is to shed light on the potential of degradable silica nanoparticles in addressing current challenges in nanomedicine, offering insights into their design, applications in tumor diagnosis and treatment, and paving the way for future advancements in clinical theranostic nanomedicines.

Implantable smart hyperthermia nanofibers for cancer therapy: Challenges and opportunities

Nanofibers (NFs) with practical drug-loading capacities, high stability, and controllable release have caught the attention of investigators due to their potential applications in on-demand drug delivery devices. Developing novel and efficient multidisciplinary management of locoregional cancer treatment through the design of smart NF-based systems integrated with combined chemotherapy and hyperthermia could provide stronger therapeutic advantages. On the other hand, implanting directly at the tumor area is a remarkable benefit of hyperthermia NF-based drug delivery approaches. Hence, implantable smart hyperthermia NFs might be very hopeful for tumor treatment in the future and provide new avenues for developing highly efficient localized drug delivery systems. Indeed, features of the smart NFs lead to the construction of a reversibly flexible nanostructure that enables hyperthermia and facile switchable release of antitumor agents to eradicate cancer cells. Accordingly, this study covers recent updates on applications of implantable smart hyperthermia NFs regarding their current scope and future outlook. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Synchronized delivery of dual-drugs for potentiating combination chemotherapy based on smart triple-responsive polymeric micelles

Here, we combined reversible addition-fragmentation chain transfer (RAFT) polymerization and amide coupling reaction to develop a novel drug-polymer conjugate using poly(AMA-co-IMMA)-b-poly(OEGMA) (termed as PAIPO) as nanocarriers. In order to enhance cellular uptake and obtain subsequent endo/lysosomal escape capacity, the dual-drugs-conjugated prodrug was then coupled with 2,3-dimethylmaleimide (DA) moieties and implanted with imidazolyl groups, respectively. Paclitaxel (PTX) was conjugated to PAIPO via 3,3'-dithiodipropionic acid (DPA) to construct a GSH-responsive moiety, while doxorubicin (DOX) was conjugated to PAIPO via 4-formyl benzoic acid to construct a pH-responsive moiety, which synergistically enabled a synchronized and precise drug delivery. The micelles self-assembled from DOX/PTX@PAIPO^DA showed an ideal average diameter (163.2-178.3 nm), contributing to passive targeting by the EPR effect. Moreover, a switch of the surface Zeta potential of micelles from steady negatively charged (- 9.74 ± 0.54 mV) at pH 7.4 to positively charged (+ 6.33 ± 1.25 mV) at pH 6.5, facilitated the long blood circulation and cellular endocytosis of micelles, respectively. More importantly, in vitro studies confirmed that ^DAM(DOX_n/PTX) exhibited a strong synergism against tumor cells, and under slightly acidic conditions (pH 6.5), the combination index (CI) values for ^DAM(DOX₁/PTX) on HeLa and Skov-3 cells were estimated to be 0.47 and 0.49 (previous to be 0.50 and 0.56 at pH 7.4), respectively. And in vivo results showed effective tumor accumulation potential, remarkable biosafety, and biocompatibility. Combined, such synchronized delivery approach based on multi-responsive micelles might potentiate the efficacy of combination chemotherapy in clinical cancer treatment.

Nanotechnology-enabled immunogenic cell death for improved cancer immunotherapy

Tumor immunotherapy has revolutionized the field of oncology treatments in recent years. As one of the promising strategies of cancer immunotherapy, tumor immunogenic cell death (ICD) has shown significant potential for tumor therapy. Nanoparticles are widely used for drug delivery due to their versatile characteristics, such as stability, slow blood elimination, and tumor-targeting ability. To increase the specificity of ICD inducers and improve the efficiency of ICD induction, functionally specific nanoparticles, such as liposomes, nanostructured lipid carriers, micelles, nanodiscs, biomembrane-coated nanoparticles and inorganic nanoparticles have been widely reported as the vehicles to deliver ICD inducers in vivo. In this review, we summarized the strategies of different nanoparticles for ICD-induced cancer immunotherapy, and systematically discussed their advantages and disadvantages as well as provided feasible strategies for solving these problems. We believe that this review will offer some insights into the design of effective nanoparticulate systems for the therapeutic delivery of ICD inducers, thus, promoting the development of ICD-mediated cancer immunotherapy.

Cancer-targeted fucoidan‑iron oxide nanoparticles for synergistic chemotherapy/chemodynamic theranostics through amplification of P-selectin and oxidative stress

A combination of chemotherapy and chemodynamic therapy (CDT) is being developed to improve the theranostic efficacy and biological safety of current therapies. However, most CDT agents are restricted due to complex issues such as multiple components, low colloidal stability, carrier-associated toxicity, insufficient reactive oxygen species generation, and poor targeting efficacy. To overcome these problems, a novel nanoplatform composed of fucoidan (Fu) and iron oxide (IO) nanoparticles (NPs) was developed to achieve chemotherapy combined with CDT synergistic treatment with a facile self-assembling manner, and the NPs were made up of Fu and IO, in which the Fu was not only used as a potential chemotherapeutic but was also designed to stabilize the IO and target P-selectin-overexpressing lung cancer cells, thereby producing oxidative stress and thus synergizing the CDT efficacy. The Fu-IO NPs exhibited a suitable diameter below 300 nm, which favored their cellular uptake by cancer cells. Microscopic and MRI data confirmed the lung cancer cellular uptake of the NPs due to active Fu targeting. Moreover, Fu-IO NPs induced efficient apoptosis of lung cancer cells, and thus offer significant anti-cancer functions by potential chemotherapeutic-CDT.

Core-satellite nanoreactors based on cationic photosensitizer modified hollow CuS nanocage for ROS diffusion enhanced phototherapy of hypoxic tumor

Photodynamic therapy (PDT) efficiency is directly affected by the reactive oxygen species (ROS) generated by photosensitizers. However, ROSs' ultrashort life span and limited diffusion distance restrict the PDT efficiency. Therefore, it is important to control the delivery strategy of photosensitizers for PDT treatment. Herein, the core-satellite nanoreactors were fabricated with oxygen generation and ROS diffusion properties. The hollow CuS encapsulating horseradish peroxidase (HRP) was combined with the cationic photosensitizers (PEI-Ce6). The unique photosensitizers delivery strategy makes the nanoreactors achieve ROS diffusion-enhanced PDT effect. First, HRP in "core" (HRP@CuS) can decompose hydrogen peroxide (H₂O₂) to O₂, increasing O₂ levels on the surface of the nanoreactor. Second, the Ce6 molecules covalent-linked with PEI are uniformly dispersed on the surface of CuS as a "satellite", avoiding Ce6 aggregation and causing more Ce6 molecules be activated to produce more ¹O₂. Due to the Ce6 was on the surface of the CuS nanocages, the generated ROS may ensure a larger diffusion range. Meanwhile, the inherently CuS nanocages exhibit photothermal and photoacoustic (PA) effect. The photothermal effect further enhances the ROS diffusion. Under the guidance of PA imaging, nanoreactors exhibit highly efficient hypoxic tumor ablation via photodynamic and photothermal effect. Overall, the core-satellite nanoreactors provide an effective strategy for tumor therapy, further promoting the research of photosensitizers delivery.

Dual "Unlocking" Strategy to Overcome Inefficient Nanomedicine Delivery and Tumor Hypoxia for Enhanced Photodynamic-Immunotherapy

Lacking blood vessels is one of the main characteristics of most solid tumors due to their rapid and unrestricted growth, which thus causes the inefficient delivery efficiency of nanomedicine and tumor hypoxia. Herein, a dual "unlocking" strategy to overcome these obstacles is proposed by combining engineered hybrid nanoparticles (named ZnPc@FOM-Pt) with dexamethasone (DXM). It is verified that pretreatment of tumors with DXM can increase intratumorally micro-vessel density (delivery "unlocking") to enhance the tumor delivery efficiency of ZnPc@FOM-Pt and decrease HIF-1α expression. Correspondingly, more Pt can catalyze tumor-overexpressed H₂ O₂ to produce oxygen to further cause hypoxia "unlocking," ultimately achieving boosted ZnPc-based photodynamic therapy in vivo (tumor inhibition rate: 99.1%). Moreover, the immunosuppressive tumor microenvironment is efficiently reversed and the therapeutic effect of anti-PD-L1-based immunotherapy is promoted by this newly designed nanomedicine. This dual "unlocking" strategy provides an innovative paradigm on simultaneously enhancing nanomedicine delivery efficacy and hypoxia relief for tumor therapy.

GSH-Responsive Organosilica Hybrid Nanosystem as a Cascade Promoter for Enhanced Starvation and Chemodynamic Therapy

Glucose oxidase (GOD)-mediated starvation therapy (ST) that causes intratumoral glucose depletion is a promising strategy for tumor treatment. However, the ultimate efficacy is inevitably limited by tumor hypoxia, as oxygen is a key component in the consumption of glucose by GOD. In this study, a kind of glutathione (GSH)-responsive organosilica hybrid micelles loaded with Mn₃ O₄ and GOD (denoted as Mn₃ O₄ @PDOMs-GOD) is ingeniously designed for enhanced ST and chemodynamic therapy (CDT). Specifically, the internalized Mn₃ O₄ @PDOMs-GOD in tumor cells consumes intracellular glucose and oxygen (O₂ ) under the catalysis of GOD to generate hydrogen peroxide (H₂ O₂ ), which is subsequently decomposed by Mn₃ O₄ to liberate O₂ . This cyclically regenerated O₂ will form a virtuous cycle of O₂ and H₂ O₂ compensation to enhance the ST outcome. Meanwhile, Mn₃ O₄ can oxidize and deplete the overexpressed GSH in the tumor microenvironment (TME) to release Mn²⁺ , which then catalyzes H₂ O₂ into highly toxic hydroxyl radicals (·OH) to accomplish chemodynamic therapy (CDT). Both in vitro and in vivo experiment results demonstrate the significant antitumor efficacy of Mn₃ O₄ @PDOMs-GOD by the cooperatively enhanced ST and CDT, suggesting the feasibility to develop promising therapeutic platforms with higher treatment efficacies.

Recent advances of bioresponsive polymeric nanomedicine for cancer therapy

A bioresponsive polymeric nanocarrier for drug delivery is able to alter its physical and physicochemical properties in response to a variety of biological signals and pathological changes, and can exert its therapeutic efficacy within a confined space. These nanosystems can optimize the biodistribution and subcellular location of therapeutics by exploiting the differences in biochemical properties between tumors and normal tissues. Moreover, bioresponsive polymer-based nanosystems could be rationally designed as precision therapeutic platforms by optimizing the combination of responsive elements and therapeutic components according to the patient-specific disease type and stage. In this review, recent advances in smart bioresponsive polymeric nanosystems for cancer chemotherapy and immunotherapy will be summarized. We mainly discuss three categories, including acidity-sensitive, redox-responsive, and enzyme-triggered polymeric nanosystems. The important issues regarding clinical translation such as reproducibility, manufacture, and probable toxicity, are also commented.

Advancements in redox-sensitive micelles as nanotheranostics: A new horizon in cancer management

World Health Organisation (WHO) delineated cancer as one of the foremost reasons for mortality with 10 million deaths in the year 2020. Early diagnosis and effective drug delivery are of utmost importance in cancer management. The entrapment of both bio-imaging dyes and drugs will open novel avenues in the area of tumor theranostics. Elevated levels of reactive oxygen species (ROS) and glutathione (GSH) are the characteristic features of the tumor microenvironment (TME). Researchers have taken advantage of these specific TME features in recent years to develop micelle-based theranostic nanosystems. This review focuses on the advantages of redox-sensitive micelles (RSMs) and supramolecular self-assemblies for tumor theranostics. Key chemical linkers employed for the tumor-specific release of the cargo have been discussed. In vitro characterisation techniques used for the characterization of RSMs have been deliberated. Potential bottlenecks that may present themselves in the bench-to-bedside translation of this technology and the regulatory considerations have been deliberated.

PEGylated drug delivery systems in the pharmaceutical field: past, present and future perspective

Target-site drug delivery systems are gaining interest in the pharmaceutical field due to their great advantages, such as higher drug dosing capacity and better bioavailability. However, some existing problems need to be overcome. As an example, interaction between blood proteins and drug delivery systems. A potent candidate to approach the mentioned problem is based on polyethylene glycol (PEG) surface modifications. This polymer acts as a protector towards the external possible interactions with other compounds, making targeted delivery possible. Diseases such as cancer, diabetes, haemophilia and pain treatment can benefit from these new systems.This review aims to give an overview of drug delivery systems based on PEGylation as surface modification as pharmaceutical approach. Moreover, a deeper insight of the properties of PEG and its advantages is given, as well as brief overview of present therapies based on this technology.

Nanoreactor activated in situ for starvation-chemodynamic therapy of breast cancer

The nano-drug delivery system activated by tumor microenvironment (TME) can effectively treat tumors with low-toxicity. Based on high level of reductive GSH in TME and different coordination properties of Fe ions, this project intended to prepare a GSH-activated cascade catalytic nanoreactor for breast cancer treatment using Fe³⁺/Fe²⁺ as the molecular switch. In this study, the glucose oxidase (GOx) loaded iron alginate nano hydrogel (FeAlg/GOx) was prepared by the simple one-step titration method. Results showed that FeAlg/GOx could remain stable during in vivo circulation to avoid hypoglycaemia. When it reached targeted tumor site, reductive GSH can reduce Fe³⁺ to Fe²⁺. Thereafter, FeAlg/GOx nanogel was broken and GOx was released to consume the essential nutrient glucose (Glu) to achieve tumor starvation therapy. Next, the substrate H₂O₂ generated by the reaction between GOx and Glu can be catalyzed by Fe²⁺ to produce highly cytotoxic •OH in situ, which could further kill tumor cells. The in vivo pharmacodynamics results demonstrated that compared with the control group (V/V0 = 8.36 ± 1.73), FeAlg/GOx group showed the most significant anti-tumor effect with V/V0 of 3.08 ± 1.06. In conclusion, this "inactivated" FeAlg/GOx nanogel can be converted into "activated" therapeutic substances in situ to achieve starvation-chemodynamic combined treatment for breast cancer.

A "Valve-Closing" Starvation Strategy for Amplification of Tumor-Specific Chemotherapy

Starvation-dependent differential stress sensitization effect between normal and tumor cells provides a potentially promising strategy to amplify chemotherapy effects and reduce side effects. However, the conventional starvation approaches such as glucose oxidase (Gox)-induced glucose depletion and nanomedicine-enabled vascular embolism usually suffer from aggravated tumor hypoxia, systemic toxicity, and unpredictable metabolic syndrome. Herein, a novel "valve-closing" starvation strategy is developed to amplify the chemotherapy effects via closing the "valve" of glucose transported into tumor cells, which is accomplished by a glucose transporters 1 (GLUT1, valve of glucose uptake) inhibitor (Genistein, Gen) and chemotherapeutic agent (Curcumin, Cur) coloaded hybrid organosilica-micelles nanomedicine (designated as (Gen + Cur)@FOS) with controllable stability. In vitro and in vivo results demonstrate that (Gen + Cur)@FOS can effectively reduce glucose/adenosine triphosphate levels in tumor cells by inhibiting GLUT1 expression (i.e., "valve-closing") to induce the starvation of tumor cells, thus weakening the resistance of tumor cells to apoptosis caused by chemotherapy, and consequently contributing to the remarkably improved antitumor efficiency and minimized side effects based on the stress sensitization effect mediated by GLUT1 inhibition-induced starvation. This "valve-closing" starvation strategy provides a promising paradigm for the development of novel nanotherapeutics with amplified chemotherapy effect.

Shielding Ferritin with a Biomineralized Shell Enables Efficient Modulation of Tumor Microenvironment and Targeted Delivery of Diverse Therapeutic Agents

Ferritin (Fn) is considered a promising carrier for targeted delivery to tumors, but the successful application in vivo has not been fully achieved yet. Herein, strong evidence is provided that the Fn receptor is expressed in liver tissues, resulting in an intercept effect in regards to tumor delivery. Building on these observations, a biomineralization technology is rationally designed to shield Fn using a calcium phosphate (CaP) shell, which can improve the delivery performance by reducing Fn interception in the liver while re-exposing it in acidic tumors. Moreover, the selective dissolution of the CaP shell not only neutralizes the acidic microenvironment but also induces the intratumoral immunomodulation and calcification. Upon multiple cell line and patient-derived xenografts, it is demonstrated that the elaboration of the highly flexible Fn@CaP chassis by loading a chemotherapeutic drug into the Fn cavity confers potent antitumor effects, and additionally encapsulating a photosensitizer into the outer shell enables a combined chemo-photothermal therapy for complete suppression of advanced tumors. Altogether, these results support Fn@CaP as a new nanoplatform for efficient modulation of the tumor microenvironment and targeted delivery of diverse therapeutic agents.

Silica-Based Stimuli-Responsive Systems for Antitumor Drug Delivery and Controlled Release

The administration of cytotoxic drugs in classical chemotherapy is frequently limited by water solubility, low plasmatic stability, and a myriad of secondary effects associated with their diffusion to healthy tissue. In this sense, novel pharmaceutical forms able to deliver selectively these drugs to the malign cells, and imposing a space-time precise control of their discharge, are needed. In the last two decades, silica nanoparticles have been proposed as safe vehicles for antitumor molecules due to their stability in physiological medium, high surface area and easy functionalization, and good biocompatibility. In this review, we focus on silica-based nanomedicines provided with specific mechanisms for intracellular drug release. According to silica nature (amorphous, mesostructured, and hybrids) nanocarriers responding to a variety of stimuli endogenously (e.g., pH, redox potential, and enzyme activity) or exogenously (e.g., magnetic field, light, temperature, and ultrasound) are proposed. Furthermore, the incorporation of targeting molecules (e.g., monoclonal antibodies) that interact with specific cell membrane receptors allows a selective delivery to cancer cells to be carried out. Eventually, we present some remarks on the most important formulations in the pipeline for clinical approval, and we discuss the most difficult tasks to tackle in the near future, in order to extend the use of these nanomedicines to real patients.

Multifunctional Nanosystems with Enhanced Cellular Uptake for Tumor Therapy

Rapid development of nanotechnology provides promising strategies in biomedicine, especially in tumor therapy. In particular, the cellular uptake of nanosystems is not only a basic premise to realize various biomedical applications, but also a fatal factor for determining the final therapeutic effect. Thus, a systematic and comprehensive summary is necessary to overview the recent research progress on the improvement of nanosystem cellular uptake for cancer treatment. According to the process of nanosystems entering the body, they can be classified into three categories. The first segment is to enhance the accumulation and permeation of nanosystems to tumor cells through extracellular microenvironment stimulation. The second segment is to improve cellular internalization from extracellular to intracellular via active targeting. The third segment is to enhance the intracellular retention of therapeutics by subcellular localization. The major factors in the delivery can be utilized to develop multifunctional nanosystems for strengthening the tumor therapy. Ultimately, the key challenges and prospective in the emerging research frontier are thoroughly outlined. This review is expected to provide inspiring ideas, promising strategies and potential pathways for developing advanced anticancer nanosystems in clinical practice.

Polyurethane-polyurea hybrid nanocapsules as efficient delivery systems of anticancer Ir(III) metallodrugs

Cyclometalated Ir(III) complexes hold great promise as an alternative to platinum metallodrugs for therapy and diagnosis of cancer. However, low aqueous solubility and poor cell membrane permeability difficult in vivo...

Thermosensitive hydrogel-functionalized gold nanorod/mesoporous MnO2 nanoparticles for tumor cell-triggered drug delivery

MnO₂ owns distinct redox, imaging, and degradable properties corresponding to the tumor microenvironment. However, the onefold structure and non-modifiable property cause many obstacles to anticancer applications. In this report, we first prepared a typical core-shell gold nanorod (GNR)/manganese dioxide (MnO₂) nanoparticles (GNR/MnO₂ NPs). Interestingly, the MnO₂ had a mesoporous channel and modifiable hydroxyl group (OH). Here, the unique 'OH' groups were modified and further grafted with poly(N-isopropylacrylamide-co-acrylic acid) (PNA). As a dual-sensitive hydrogel, it was selected as the thermal/pH-sensitive component in the hybrid nanoparticles (GNR/MnO₂/PNA NPs). The anticancer drug doxorubicin hydrochloride (DOX) was selected and loaded into the hybrid nanoparticles (GNR/MnO₂/PNA-DOX NPs). The GNR/MnO₂/PNA NPs achieved satisfying drug-loading efficiency and glutathione (GSH)/pH/thermal-responsive drug-controlled release. As a side benefit, the GNR/MnO₂/PNA NPs showed potential as excellent near-infrared (NIR)-excited nanoplatforms for photothermal therapy (PTT). Delightedly, the studies demonstrated that the GNR/MnO₂/PNA-DOX NPs showed a noticeable killing effect on tumor cells, whether it is tumor cell-triggered drug release or photothermal effect. Besides, it not only could enhance mitochondrial damage but also could inhibit the migration and invasion of tumor cells. Quite the reverse, it had little negative impact on normal cells. The feature can prevent anticancer drugs and nanoparticles from killing normal cells. Consequently, GNR/MnO₂/PNA NPs have potential applications in drug delivery and synergistic therapy due to these advantageous features.

Asymmetric polymersomes, from the formation of asymmetric membranes to the application on drug delivery

Nano drug delivery systems have attracted researchers' growing attention and are gradually emerging into the public views. More and more nano-formulations are being approved for marketing or clinical use, representing the field's booming development. Copolymer self-assembly systems such as micelles, nanoparticles, polymersomes occupy a prominent position in the field of nano-drug delivery carriers. Among them, polymersomes, unlike micelles or nanoparticles, resemble liposomes' structure and possess large internal hollow hydrophilic reservoirs, allowing them to carry hydrophilic drugs. Nevertheless, their insufficient drug loading efficiency and unruly self-assembly morphology have somewhat constrained their applications. Especially for the delivery of biomacromolecule such as peptides, the encapsulation efficiency is always considered to be a formidable obstacle, even if the enormous hydrophilic core would render the polymersomes to have considerable potential in this regard. Reassuringly, the emergence of asymmetric polymersomes holds the prospect of solving this problem. With the development of synthetic technology and a deeper understanding of the self-assembly process, the asymmetric polymersomes which are with different inner and outer shell composition have been gradually recognized by researchers. It has made possible elevated drug loading, more controllable assembly processes and release performance. The internal hydrophilic blocks different from the outer shell could be engineered to have a more remarkable affinity to the cargos or could contain a non-watery aqueous phase to enable the thermodynamically preferred encapsulation of cargos, which would allow for a substantial improvement in drug encapsulation efficiency compared to the conventional approach. In this paper, we aim to deepen the understanding to asymmetric polymersomes and lay the foundation for the development of this field by describing four main elements: the mechanism of their preparation and asymmetric membrane formation process, the characterization of asymmetric membranes, the efficient drug loading, and the special stimulus-responsive release mechanism.

Peroxisome inspired hybrid enzyme nanogels for chemodynamic and photodynamic therapy

Peroxisome, a special cytoplasmic organelle, possesses one or more kinds of oxidases for hydrogen peroxide (H₂O₂) production and catalase for H₂O₂ degradation, which serves as an intracellular H₂O₂ regulator to degrade toxic peroxides to water. Inspired by this biochemical pathway, we demonstrate the reactive oxygen species (ROS) induced tumor therapy by integrating lactate oxidase (LOx) and catalase (CAT) into Fe₃O₄ nanoparticle/indocyanine green (ICG) co-loaded hybrid nanogels (designated as FIGs-LC). Based on the O₂ redistribution and H₂O₂ activation by cascading LOx and CAT catalytic metabolic regulation, hydroxyl radical (·OH) and singlet oxygen (¹O₂) production can be modulated for glutathione (GSH)-activated chemodynamic therapy (CDT) and NIR-triggered photodynamic therapy (PDT), by manipulating the ratio of LOx and CAT to catalyze endogenous lactate to produce H₂O₂ and further cascade decomposing H₂O₂ into O₂. The regulation reactions of FIGs-LC significantly elevate the intracellular ROS level and cause fatal damage to cancer cells inducing the effective inhibition of tumor growth. Such enzyme complex loaded hybrid nanogel present potential for biomedical ROS regulation, especially for the tumors with different redox state, size, and subcutaneous depth.

The control of reactive oxygen species in cancer cells is an attractive approach for anticancer applications. Here, the authors create a peroxisome inspired lactate oxidase and catalase loaded hydrogel with iron nanoparticles and NIR photosensitizer for glutathione activated chemodynamic and photodynamic therapy.

Smart stimuli-responsive nanocarriers for the cancer therapy – nanomedicine

Nanomedicine is ongoing current research in the applications of nanotechnology for cancer therapy. Simply from a technology perspective, this field of research has an enormous broadening and success to date. Recently, nanomedicine has also made inroads in the treatment of cancer. Stimuli-responsive nanoparticles are an emerging field of research because its targeting capacity is of great interest in the treatment of cancer. The responsive nanoparticles are efficient in encountering different internal biological stimuli (acidic, pH, redox, and enzyme) and external stimuli (temperature, ultrasounds, magnetic field, and light), which are used as smart nanocarriers for delivery of the chemotherapeutic and imaging agents for cancer therapy. In-depth, the responsive nanocarrier that responds to the biological cues is of pronounced interest due to its capability to provide a controlled release profile at the tumor-specific site. The outlook of this review focuses on the stimuli-responsive nanocarrier drug delivery systems in sequence to address the biological challenges that need to be evaluated to overcome conventional cancer therapy.

A Biomimetic Aggregation-Induced Emission Photosensitizer with Antigen-Presenting and Hitchhiking Function for Lipid Droplet Targeted Photodynamic Immunotherapy

Photodynamic therapy (PDT) is a promising alternative approach for effective cancer treatment that is associated with an antitumor immune response. However, immunosuppression of the tumor microenvironment limits the immune response induced by PDT. Stimulation and proliferation of T cells is a critical step for generating immune responses and depends on the efficient presentation of tumor antigens and co-stimulatory molecules by antigen-presenting cells (APCs). Here, biomimetic aggregation-induced emission (AIE) photosensitizers with antigen-presenting and hitchhiking abilities (DC@AIEdots) are developed by coating dendritic cell (DC) membranes on the nanoaggregates of the AIEgens. Notably, the inner AIE molecules can selectively accumulate in lipid droplets of tumor cells, and the outer cell membrane can facilitate the hitchhiking of DC@AIEdots onto the endogenous T cells and enhance the tumor delivery efficiency by about 1.6 times. Furthermore, DC@AIEdots can stimulate the in vivo proliferation and activation of T cells and trigger the immune system. The potential applications of therapeutic agents targeting lipid droplets for immunotherapy are indicated and a new hitchhiking approach for drug delivery is provided. Lastly, the study presents a photoactive and artificial antigen-presenting platform for effective T cell stimulation and cancer photodynamic immunotherapy.

Photoacoustic Force-Guided Precise and Fast Delivery of Nanomedicine with Boosted Therapeutic Efficacy

Precise and efficient delivery of nanomedicine to the target site has remained as a major roadblock in advanced cancer treatment. Here, a novel photoacoustic force (PAF)-guided nanotherapeutic system is reported based on a near-infrared (NIR)-absorbing semiconducting polymer (SP), showing significantly improved tumor accumulation and deep tissue penetration for enhanced phototherapeutic efficacy. The accumulation of nanoparticles in 4T1 tumor-bearing mice induced by the PAF strategy displays a fivefold enhancement in comparison with that of the traditional passive targeting pathway, in a significantly shortened time (45 min vs 24 h) with an enhanced penetration depth in tumors. Additionally, a tumor-bearing mouse model is rationally designed to unveil the mechanism, indicating that the nanoparticles enter solid tumors through enhanced transportation across blood vessel barriers via both inter-endothelial gaps and active trans-endothelial pathways. This process is specifically driven by PAF generated from the nanoparticles under NIR laser irradiation. The study thus demonstrates a new nanotherapeutic strategy with low dose, enhanced delivery efficiency in tumor, and boosted therapeutic efficacy, opening new doors for designing novel nanocarriers.

Tumor Microenvironment-Responsive Shell/Core Composite Nanoparticles for Enhanced Stability and Antitumor Efficiency Based on a pH-Triggered Charge-Reversal Mechanism

High systemic stability and effective tumor accumulation of chemotherapeutic agents are indispensable elements that determine their antitumor efficacy. PEGylation of nanoparticles (NPs) could prolong the retention time in vivo by improving their stability in circulation, but treatment suffers reduced tumor penetration and cellular uptake of nanomedicines. The tumor microenvironment (TME)-responsive NPs maintain their stealth features during circulation and undergo a stimuli-responsive dePEGylation once exposed to the site of action, thereby achieving enhanced internalization in tumor cells. Herein, TME-responsive shell/core composite nanoparticles were prepared and optimized with enhanced stability and tumor intake efficiency. We synthesized 12-hydroxystearic acid-poly (ethylene glycol)-YGRKKRRQRRR (HA-PEG-TAT) as a post-insert apparatus in disulfiram (DSF)-encapsulated naked nanoparticles (N-NPs) in order to form a cationic core (TAT-NPs). Accordingly, the negatively charged poly (glutamate acid)-graft-poly (ethylene glycol) (PGlu-PEG) was further applied to the surface of TAT-NPs as a negative charged shell (PGlu-PEG/TAT-NPs) via the electrostatic interaction between glutamic acids and arginine at the outer ring of the TAT-NPs. PGlu-PEG/TAT-NPs displayed a huge loading capability for DSF with reduced degradation in plasma and exhibited rapid charge reversal when pH decreased from 7.4 to pH 6.5, demonstrating an excellent systemic stability as well as intelligent stimuli-responsive performance within the acidic TME. Furthermore, the in vivo antitumor study revealed that PGlu-PEG/TAT-NPs provided greater antitumor efficacy compared with free DSF and N-NPs with no obvious systemic toxicity. In conclusion, the TME-responsive shell/core composite NPs, consisting of PGlu-PEG and HS-PEG-TAT, could mediate an effective and biocompatible delivery of chemotherapeutic agents with clinical potential.

The Fate of Nanoparticles In Vivo and the Strategy of Designing Stealth Nanoparticle for Drug Delivery

Nano-drug delivery systems (Nano-DDS) offer powerful advantages in drug delivery and targeted therapy for diseases. Compared to the traditional drug formulations, Nano-DDS can increase solubility, biocompatibility, and reduce off-targeted side effects of free drugs. However, they still have some disadvantages that pose a limitation in reaching their full potential in clinical use. Protein adsorption in blood, activation of the complement system, and subsequent sequestration by the mononuclear phagocyte system (MPS) consequently result in nanoparticles (NPs) to be rapidly cleared from circulation. Therefore, NPs have low drug delivery efficiency. So, it is important to develop stealth NPs for reducing bio-nano interaction. In this review, we first conclude the interaction between NPs and biological environments, such as blood proteins and MPS, and factors influencing each other. Next, we will summarize the new strategies to reduce NPs protein adsorption and uptake by the MPS based on current knowledge of the bio-nano interaction. Further directions will also be highlighted for the development of biomimetic stealth nano-delivery systems by combining targeted strategies for a better therapeutic effect.

T cell membrane cloaking tumor microenvironment-responsive nanoparticles with a smart "membrane escape mechanism" for enhanced immune-chemotherapy of melanoma

The application of combination immune-chemotherapy makes up for the limitation of monotherapy and achieves superior antitumor activity against cancer. However, combinational therapy is always restricted by poor tumor targeted drug delivery efficacy. Herein, novel T cell membrane cloaking tumor microenvironment-responsive nanoparticles (PBA modified T cell membrane cloaking hyaluronic acid (HA)-disulfide bond-vitamin E succinate/curcumin, shortened as RCM@T) were developed. T cell membrane cloaking not only serves as a protection shell for sufficient drug delivery but also acts as a programmed cell death-1(PD-1) "antibody" to selectively bind the PD-L1 of tumor cells. When RCM@T is intravenously administrated into the blood stream, it accumulates at tumor sites and responds to an acidic pH to achieve a "membrane escape effect" and expose the HA residues of RCM for tumor targeted drug delivery. RCM accumulates in the cytoplasm via CD44 receptor mediated endocytosis and intracellularly releases antitumor drug in the intracellular redox microenvironment for tumor chemotherapy. T cell membrane debris targets the PD-L1of tumor cells for tumor immunotherapy, which not only directly kills tumor cells, but also improves the CD8+ T cell level and facilitates effector cytokine release. Taken together, the as-constructed RCM@T creates a new way for the rational design of a drug delivery system via the combination of stimuli-responsive drug release, chemotherapeutical agent delivery and cell membrane based immune checkpoint blockade immunotherapy.

Matrix Metalloproteinase-9-Responsive Surface Charge-Reversible Nanocarrier to Enhance Endocytosis as Efficient Targeted Delivery System for Cancer Diagnosis and Therapy

Nanoparticles, that can be enriched in the tumor microenvironment and deliver the payloads into cancer cells, are desirable carriers for theranostic agents in cancer diagnosis and treatment. However, efficient targeted delivery and enhanced endocytosis for probes and drugs in theranostics are still major challenges. Here, a nanoparticle, which is capable of charge reversal from negative to positive in response to matrix metalloproteinase 9 (MMP9) in tumor microenvironment is reported. This nanoparticle is based on a novel charge reversible amphiphilic molecule consisting of hydrophobic oleic acid, MMP9-cleavable peptide, and glutamate-rich segment (named as OMPE). The OMPE-modified cationic liposome forms an intelligent anionic nanohybrid (O-NP) with enhanced endocytosis through surface charge reversal in response to MMP9 in vitro. Successfully, O-NP nanohybrid performs preferential accumulation and enhances the endocytosis in MMP9-expressing xenografted tumors in mouse models, which improve the sensitivity of diagnosis agents and the antitumor effects of drugs in vivo by overcoming their low solubility and/or nonspecific enrichment. These results indicate that O-NP can be a promising delivery platform for cancer diagnosis and therapy.

A new pH/NIR responsive theranostic agent for magnetic resonance imaging guided synergistic therapy

New nano-reagents with diagnostic imaging and therapeutic functions are very important for precision medicine against cancer. In this work, a new nanotheraontic agent for magnetic resonance imaging (MRI) guided combined photothermal therapy (PTT) and chemotherapy was constructed based on polydopamine (PDA) functionalized copper ferrite nanospheres (PDA@CFNs). The high relaxivity makes it possible for PDA@CFNs to become a promising MRI contrast agent, providing necessary and exhaustive information for tumor diagnosis. In addition, because both CFNs and PDA have strong near-infrared (NIR) absorption, PDA@CFNs exhibit excellent photothermal performance. Highly effective tumor ablation is achieved in a mouse model through PTT and pH/NIR triggered on-demand chemotherapy. These findings reveal that constructing smart pH/NIR responsive multifunctional theranostic agents is a feasible strategy for precision cancer therapy.

Biodegradable Multifunctional Nanotheranostic Based on Ag2S-Doped Hollow BSA-SiO2 for Enhancing ROS-Feedback Synergistic Antitumor Therapy

Stimuli-responsive silica nanoparticles are an attractive therapeutic agent for effective tumor ablation, but the responsiveness of silica nanoagents is limited by intrastimulation level and silica framework structure. Herein, a biodegradable hollow SiO₂-based nanosystem (Ag₂S-GOx@BHS NYs) is developed by a novel one-step dual-template (bovine serum albumin (BSA) and cetyltrimethylammonium bromide (CTAB)) synthetic strategy for image-guided therapy. The Ag₂S-GOx@BHS NYs can be specifically activated in the tumor microenvironment via a self-feedback mechanism to achieve reactive oxygen species (ROS)-induced multistep therapy. In response to the inherent acidity and H₂O₂ at the tumor sites, Ag₂S-GOx@BHS would accelerate the structural degradation while releasing glucose oxidase (GOx), which could efficiently deplete intratumoral glucose to copious amounts of gluconic acid and H₂O₂. More importantly, the sufficient H₂O₂ not only acts as a reactant to generate Ag⁺ from Ag₂S for metal-ion therapy and improves the oxidative stress but also combines with gluconic acid results in the self-accelerating degradation process. Moreover, the released Ag₂S nanoparticles can help the Ag₂S-GOx@BHS NYs realize the second near-infrared window fluorescence (NIR-II FL) and photoacoustic (PA) imaging-guided precise photothermal therapy (PTT). Taken together, the development of a self-feedback nanosystem may open up a new dimension for a highly effective multistep tumor therapy.

Near-Infrared Light Irradiation Induced Mild Hyperthermia Enhances Glutathione Depletion and DNA Interstrand Cross-Link Formation for Efficient Chemotherapy

DNA alkylating agents generally kill tumor cells by covalently binding with DNA to form interstrand or intrastrand cross-links. However, in the case of cisplatin, only a few DNA adducts (<1%) are highly toxic irreparable interstrand cross-links. Furthermore, cisplatin is rapidly detoxified by high levels of intracellular thiols such as glutathione (GSH). Since the discovery of its mechanism of action, people have been looking for ways to directly and efficiently remove intracellular GSH and increase interstrand cross-links to improve drug efficacy and overcome resistance, but there has been little breakthrough. Herein, we hypothesized that the anticancer efficiency of cisplatin can be enhanced through iodo-thiol click chemistry mediated GSH depletion and increased formation of DNA interstrand cross-links via mild hyperthermia triggered by near-infrared (NIR) light. This was achieved by preparing an amphiphilic polymer with platinum(IV) (Pt(IV)) prodrugs and pendant iodine atoms (iodides). The polymer was further used to encapsulate IR780 and assembled into Pt-I-IR780 nanoparticles. Induction of mild hyperthermia (43 °C) at the tumor site by NIR light irradiation had three effects: (1) it accelerated the GSH-mediated reduction of Pt(IV) in the polymer main chain to platinum(II) (Pt(II)); (2) it boosted the iodo-thiol substitution click reaction between GSH and iodide, thereby attenuating the GSH-mediated detoxification of cisplatin; (3) it increased the proportion of highly toxic and irreparable Pt-DNA interstrand cross-links. Therefore, we find that mild hyperthermia induced via NIR irradiation can enhance the killing of cancer cells and reduce the tumor burden, thus delivering efficient chemotherapy.

Reduction-responsive polymers for drug delivery in cancer therapy-Is there anything new to discover?

Among various types of stimuli-responsive drug delivery systems, reduction-responsive polymers have attracted great interest. In general, these systems have high stability in systemic circulation, however, they can respond quickly to differences in the concentrations of reducing species in specific physiological sites associated with a pathology. This is a particularly relevant strategy to target diseases in which hypoxic regions are present, as polymers which are sensitive to in-situ expressed antioxidant species can, through a local response, release a therapeutic at high concentration in the targeted site, and thus, improve the selectivity and efficacy of the treatment. At the same time, such reduction-responsive materials can also decrease the toxicity and side effects of certain drugs. To date, polymers containing disulfide linkages are the most investigated of the class of reduction-responsive nanocarriers, however, other groups such as selenide and diselenide have also been used for the same purpose. In this review article, we discussed the rationale behind the development of reduction-responsive polymers as drug delivery systems and highlight examples of recent progress. We include the most popular design methods to generate reduction-responsive polymeric carriers and their applications in cancer therapy, and question what areas may still need to be explored in a field with already a very large number of research articles. Finally, we consider the main challenges associated with the clinical translation of these nanocarriers and the future perspectives in this area. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nanoplatform-based cascade engineering for cancer therapy

Various therapeutic techniques have been studied for treating cancer precisely and effectively, such as targeted drug delivery, phototherapy, tumor-specific catalytic therapy, and synergistic therapy, which, however, evoke numerous challenges due to the inherent limitations of these therapeutic modalities and intricate biological circumstances as well. With the remarkable advances of nanotechnology, nanoplatform-based cascade engineering, as an efficient and booming strategy, has been tactfully introduced to optimize these cancer therapies. Based on the designed nanoplatforms, pre-supposed cascade processes could be triggered under specific conditions to generate/deliver more therapeutic species or produce stronger tumoricidal effects inside tumors, aiming to achieve cancer therapy with increased anti-tumor efficacy and diminished side effects. In this review, the recent advances in nanoplatform-based cascade engineering for cancer therapy are summarized and discussed, with an emphasis on the design of smart nanoplatforms with unique structures, compositions and properties, and the implementation of specific cascade processes by means of endogenous tumor microenvironment (TME) resources and/or exogenous energy inputs. This fascinating strategy presents unprecedented potential in the enhancement of cancer therapies, and offers better controllability, specificity and effectiveness of therapeutic functions compared to the corresponding single components/functions. In the end, challenges and prospects of such a burgeoning strategy in the field of cancer therapy will be discussed, hopefully to facilitate its further development to meet the personalized treatment demands.

A dendritic, redox-responsive, supramolecular (Dr.S) system for lysis-triggered delivery for drug-resistant renal cancer

Purpose: Aiming to improve the drug loading capacity of dendritic nanoparticles and enhance delivery efficacy in drug-resistant cancer, we developed and optimized a more advanced dendritic, redox-responsive, supramolecular (Dr.S) system for intravenous RAD001 administration. Materials and methods: The Dr.S system was engineered by linking 3^rd generation polyamidoamine dendrimers (G3 PAMAM) with 8-arm polyethylene glycol (PEG) to encapsulate a molecular targeted agent RAD001. The drug-loading capacity was measured by ultraviolet-visible spectrophotometry. In vitro release behavior was determined with a two-compartment model, and the in vivo distribution pattern was tracked by Cy5.5 fluorescence. The therapeutic effect of Dr.S/RAD001 was evaluated in RAD001-resistant cancer cells and tumor-bearing nude mice, respectively. Results: The Dr.S system encapsulating RAD001 with a loading efficiency of 10.6% formed a core–shell structure, by shifting hydrophobic PAMAM/RAD001 components towards inner space and exposing the hydrophilic PEG on the surface. The Dr.S/RAD001 system could respond to a lysis-mimicking reduction stimulus, and functionally release cargoes to facilitate tumor accumulation and cellular internalization. These features contributed to the enhanced anti-tumor activity of RAD001 in renal cancers in vitro and in vivo. The Dr.S/RAD001 system also reversed acquired RAD001-resistance by a 60-fold increase in tumor accumulation of the therapeutics. Conclusion: The functional Dr.S/RAD001 system enables lysis-triggered release of RAD001 to achieve better tumor accumulation, which helps overcome acquired drug resistance in renal cancers.

Aiming to improve the drug loading capacity of dendritic nanoparticles and enhance delivery efficacy in drug-resistant cancer, we developed and optimized a more advanced dendritic, redox-responsive, supramolecular (Dr.S) system for intravenous RAD001 administration.

Stimulus-Responsive Nanomedicines for Disease Diagnosis and Treatment

Stimulus-responsive drug delivery systems generally aim to release the active pharmaceutical ingredient (API) in response to specific conditions and have recently been explored for disease treatments. These approaches can also be extended to molecular imaging to report on disease diagnosis and management. The stimuli used for activation are based on differences between the environment of the diseased or targeted sites, and normal tissues. Endogenous stimuli include pH, redox reactions, enzymatic activity, temperature and others. Exogenous site-specific stimuli include the use of magnetic fields, light, ultrasound and others. These endogenous or exogenous stimuli lead to structural changes or cleavage of the cargo carrier, leading to release of the API. A wide variety of stimulus-responsive systems have been developed-responsive to both a single stimulus or multiple stimuli-and represent a theranostic tool for disease treatment. In this review, stimuli commonly used in the development of theranostic nanoplatforms are enumerated. An emphasis on chemical structure and property relationships is provided, aiming to focus on insights for the design of stimulus-responsive delivery systems. Several examples of theranostic applications of these stimulus-responsive nanomedicines are discussed.

Recent advances of sorafenib nanoformulations for cancer therapy: Smart nanosystem and combination therapy

Sorafenib, a molecular targeted multi-kinase inhibitor, has received considerable interests in recent years due to its significant profiles of efficacy in cancer therapy. However, poor pharmacokinetic properties such as limited water solubility, rapid elimination and metabolism lead to low bioavailability, restricting its further clinical application. Over the past decade, with substantial progress achieved in the development of nanotechnology, various types of smart sorafenib nanoformulations have been developed to improve the targetability as well as the bioavailability of sorafenib. In this review, we summarize various aspects from the preparation and characterization to the evaluation of antitumor efficacy of numerous stimuli-responsive sorafenib nanodelivery systems, particularly with emphasis on their mechanism of drug release and tumor microenvironment response. In addition, this review makes great effort to summarize the nanosystem-based combination therapy of sorafenib with other antitumor agents, which can provide detailed information for further synergistic cancer therapy. In the final section of this review, we also provide a detailed discussion of future challenges and prospects of designing and developing ideal sorafenib nanoformulations for clinical cancer therapy.

Trends in Degradable Mesoporous Organosilica-Based Nanomaterials for Controlling Drug Delivery: A Mini Review

The last few years of enhancing the design of hybrid mesoporous organosilica nanoparticleshas allowed their degradation under specific pathologic conditions, which finally is showing a lightin their potential use as drug delivery systems towards clinical trials. Nevertheless, the issueof controlling the degradation on-demand at cellular level still remains a major challenge, even if ithas lately been addressed through the incorporation of degradable organo-bridged alkoxysilanesinto the silica framework. On this basis, this mini review covers some of the most recent examplesof dierent degradable organosilica nanomaterials with potential application in nanomedicine,from degradable non-porous to mesoporous organosilica nanoparticles (MONs), functionalized withresponsive molecular gates, and also the very promising degradable periodic mesoporous organosilicamaterials (PMOs) only consisting of organosilica bridges.

Smart stimuli-responsive drug delivery systems based on cyclodextrin: A review

Stimulated by researches in materials chemistry and medicine fields, drug delivery has entered a new stage of development. Drug delivery systems have been extensively studied according to the differences in the drug therapeutic environment such as pH, light, temperature, magnet, redox, enzymes, etc. Cyclodextrin is a smart tool that has been proven to be used in the preparation of drug delivery, and has become a new area of concern in recent years. In this review, we discuss recent research advances in smart stimuli-responsive cyclodextrin-based drug delivery. First, different stimuli-responsive drug delivery systems based on cyclodextrin are introduced and classified. Then, the characteristics of different types of stimuli-responsive drug delivery systems are described, and their applications are emphasized. Finally, current challenges and future development opportunities of smart stimuli-responsive drug delivery systems based on cyclodextrin are discussed.

Polymer-Encapsulated Cobalt/Gold Bimetallic Nanoclusters as Stimuli-Responsive Chemiluminescent Nanoprobes for Reactive Oxygen Species

A stimuli-responsive chemiluminescent nanocomposite was developed based on bimetallic nanoclusters encapsulated in a reactive oxygen species (ROS)-responsive polymer for a highly sensitive determination of ROS (i.e., H₂O₂) in biological samples. Cobalt/gold bimetallic nanoclusters (GSH@Co-AuNCs) were synthesized using glutathione (GSH) as a reducing-cum-protecting reagent. The GSH-coated nanoclusters were covalently bound to N-(4-aminobutyl)-N-ethylisoluminol (ABEI) to form the GSH@Co-AuNCs-ABEI, which was further encapsulated in polymeric ROS-sensitive boronic ester modified dextran (Oxi-Dex) nanospheres through hydrophobic interactions. The stimulation of H₂O₂, as a model ROS, led to a sustainable structural cleavage of the Co-AuNCs-ABEI@Oxi-Dex nanocomposites and release of internal GSH@Co-AuNCs-ABEI, accompanied by intense chemiluminescence (CL). On this basis, an enzyme-free and reagent-free CL sensor was developed for a highly sensitive and selective determination of H₂O₂ with a detection limit of 35.8 pM in biological samples. It is of great application potential for the determination of ROS related to various diseases.

Endogenous Hydrogen Sulfide-Triggered MOF-Based Nanoenzyme for Synergic Cancer Therapy

The developing nanoparticle therapeutic agents triggered by tumor microenvironment are a feasible strategy for the substantial elevation of accuracy of diagnosis and the reduction of side effects in cancer treatments. Dysregulated H₂S production from the enzyme system of overexpressed cystathionine β-synthase has long been considered to act as an autocrine and paracrine factor for the tumor growth and proliferation of colon cancer. Herein, for the first time, an endogenous H₂S-activated copper metal-organic framework (Cu-MOF; HKUST-1) nanoenzyme has been demonstrated to synergistically mediate H₂S-activated near-infrared photothermal therapy and chemodynamic therapy in the effective treatment of colon cancer. This endogenous biomarker-triggered "turn-on" strategy to generate therapeutic agents in situ could largely simplify the constitution of nanomedicine by avoiding the cargo introduction and thus supply great promise for the precise treatments of colon cancer.

Glutathione-responsive nanoscale MOFs for effective intracellular delivery of the anticancer drug 6-mercaptopurine

A glutathione-responsive drug-delivery platform based on nanoMOFs was developed for selective cancer therapy through the introduction of disulfide bonds.