Bioorthogonal catalytic patch

In situ bioorthogonal-modulation of m6A RNA methylation in macrophages for efficient eradication of intracellular bacteria

N6-Methyladenosine (m6A) methylation plays a critical role in controlling the RNA fate. Emerging evidence has demonstrated that aberrant m6A methylation in immune cells such as macrophages could alter cell homeostasis and function, which can be a promising target for disease treatment. Despite tremendous progress in regulating the level of m6A methylation, the current methods suffer from the time-consuming operation and annoying off-target effect, which hampers the in situ manipulation of m6A methylation. Here, a bioorthogonal in situ modulation strategy of m6A methylation was proposed. Well-designed covalent organic framework (COF) dots (CIDM) could deprotect the agonist prodrug of m6A methyltransferase, resulting in a considerable hypermethylation of m6A modification. Simultaneously, the bioorthogonal catalyst CIDM showed oxidase (OXD)-mimic activity that further promoted the level of m6A methylation. Ultimately, the potential therapeutic effect of bioorthogonal controllable regulation of m6A methylation was demonstrated through intracellular bacteria eradication. The remarkable antimicrobial outcomes indicate that upregulating m6A methylation in macrophages could reprogram them into the M1 phenotype with high bactericidal activity. We believe that our bioorthogonal chemistry-controlled epigenetics regulatory strategy will provide a unique insight into the development of controllable m6A methylation.

Research Progress of Hydrogel Microneedles in Wound Management

Microneedles are a novel drug delivery system that offers advantages such as safety, painlessness, minimally invasive administration, simplicity of use, and controllable drug delivery. As a type of polymer microneedle with a three-dimensional network structure, hydrogel microneedles (HMNs) possess excellent biocompatibility and biodegradability and encapsulate various therapeutic drugs while maintaining drug activity, thus attracting significant attention. Recently, they have been widely employed to promote wound healing and have demonstrated favorable therapeutic effects. Although there are reviews about HMNs, few of them focus on wound management. Herein, we present a comprehensive overview of the design and preparation methods of HMNs, with a particular emphasis on their application status in wound healing, including acute wound healing, infected wound healing, diabetic wound healing, and scarless wound healing. Finally, we examine the advantages and limitations of HMNs in wound management and provide suggestions for future research directions.

Grooved Microneedle Patch Augments Adoptive T Cell Therapy Against Solid Tumors via Diverting Regulatory T Cells

The efficacy of adoptive T cell therapy (ACT) for the treatment of solid tumors remains challenging. In addition to the poor infiltration of effector T (Teff) cells limited by the physical barrier surrounding the solid tumor, another major obstacle is the extensive infiltration of regulatory T (Treg) cells, a major immunosuppressive immune cell subset, in the tumor microenvironment. Here, this work develops a grooved microneedle patch for augmenting ACT, aiming to simultaneously overcome physical and immunosuppressive barriers. The microneedles are engineered through an ice-templated method to generate the grooved structure for sufficient T-cell loading. In addition, with the surface modification of chemokine CCL22, the MNs could not only directly deliver tumor-specific T cells into solid tumors through physical penetration, but also specifically divert Treg cells from the tumor microenvironment to the surface of the microneedles via a cytokine concentration gradient, leading to an increase in the ratio of Teff cells/Treg cells in a mouse melanoma model. Consequently, this local delivery strategy of both T cell receptor T cells and chimeric antigen receptor T cells via the CCL22-modified grooved microneedles as a local niche could significantly enhance the antitumor efficacy and reduce the on-target off-tumor toxicity of ACT.

A Hemoglobin Bionics-Based System for Combating Antibiotic Resistance in Chronic Diabetic Wounds via Iron Homeostasis Regulation

Owing to the increased tissue iron accumulation in patients with diabetes, microorganisms may activate high expression of iron-involved metabolic pathways, leading to the exacerbation of bacterial infections and disruption of systemic glucose metabolism. Therefore, an on-demand transdermal dosing approach that utilizes iron homeostasis regulation to combat antimicrobial resistance is a promising strategy to address the challenges associated with low administration bioavailability and high antibiotic resistance in treating infected diabetic wounds. Here, it is aimed to propose an effective therapy based on hemoglobin bionics to induce disturbances in bacterial iron homeostasis. The preferred "iron cargo" is synthesized by protoporphyrin IX chelated with dopamine and gallium (PDGa), and is delivered via a glucose/pH-responsive microneedle bandage (PDGa@GMB). The PDGa@GMB downregulates the expression levels of the iron uptake regulator (Fur) and the peroxide response regulator (perR) in Staphylococcus aureus, leading to iron nutrient starvation and oxidative stress, ultimately suppressing iron-dependent bacterial activities. Consequently, PDGa@GMB demonstrates insusceptibility to genetic resistance while maintaining sustainable antimicrobial effects (>90%) against resistant strains of both S. aureus and E. coli, and accelerates tissue recovery (<20 d). Overall, PDGa@GMB not only counteracts antibiotic resistance but also holds tremendous potential in mediating microbial-host crosstalk, synergistically attenuating pathogen virulence and pathogenicity.

Regioselective epitaxial growth of metallic heterostructures

Constructing regioselective architectures in heterostructures is important for many applications; however, the targeted design of regioselective architectures is challenging due to the sophisticated processes, impurity pollution and an unclear growth mechanism. Here we successfully realized a one-pot kinetically controlled synthetic framework for constructing regioselective architectures in metallic heterostructures. The key objective was to simultaneously consider the reduction rates of metal precursors and the lattice matching relationship at heterogeneous interfaces. More importantly, this synthetic method also provided phase- and morphology-independent behaviours as foundations for choosing substrate materials, including phase regulation from Pd20Sb7 hexagonal nanoplates (HPs) to Pd8Sb3 HPs, and morphology regulation from Pd20Sb7 HPs to Pd20Sb7 rhombohedra and Pd20Sb7 nanoparticles. Consequently, the activity of regioselective epitaxially grown Pt on Pd20Sb7 HPs was greatly enhanced towards the ethanol oxidation reaction; its activity was 57 times greater than that of commercial Pt/C, and the catalyst showed increased stability (decreasing by 16.3% after 2,000 cycles) and selectivity (72.4%) compared with those of commercial Pt/C (56.0%, 18.2%). This work paves the way for the design of unconventional well-defined heterostructures for use in various applications.

Transdermal microarrayed electroporation for enhanced cancer immunotherapy based on DNA vaccination

Despite the tremendous clinical potential of nucleic acid-based vaccines, their efficacy to induce therapeutic immune response has been limited by the lack of efficient local gene delivery techniques in the human body. In this study, we develop a hydrogel-based organic electronic device (μEPO) for both transdermal delivery of nucleic acids and in vivo microarrayed cell electroporation, which is specifically oriented toward one-step transfection of DNAs in subcutaneous antigen-presenting cells (APCs) for cancer immunotherapy. The μEPO device contains an array of microneedle-shaped electrodes with pre-encapsulated dry DNAs. Upon a pressurized contact with skin tissue, the electrodes are rehydrated, electrically triggered to release DNAs, and then electroporate nearby cells, which can achieve in vivo transfection of more than 50% of the cells in the epidermal and upper dermal layer. As a proof-of-concept, the μEPO technique is employed to facilitate transdermal delivery of neoantigen genes to activate antigen-specific immune response for enhanced cancer immunotherapy based on a DNA vaccination strategy. In an ovalbumin (OVA) cancer vaccine model, we show that high-efficiency transdermal transfection of APCs with OVA-DNAs induces robust cellular and humoral immune responses, including antigen presentation and generation of IFN-γ+ cytotoxic T lymphocytes with a more than 10-fold dose sparing over existing intramuscular injection (IM) approach, and effectively inhibits tumor growth in rodent animals.

Nitric Oxide-Activated Bioorthogonal Codelivery Nanoassembly for In Situ Synthesis of Photothermal Agent for Precise and Safe Anticancer Treatment

The development of bioorthogonal activation in drug release represents a promising avenue for precise and safe anticancer treatment. However, two significant limitations currently hinder their clinical application: i) the necessity for separate administration of the drug precursor and its corresponding activator, leading to poor drug accumulation and potential side effects; ii) the reliance on exogenous metal or organic activators for triggering bioorthogonal activation, which often exhibit low efficiency and systemic toxicity when extending to living animals. To overcome these limitations, a nitric oxide (NO)-mediated bioorthogonal codelivery nanoassembly, termed TTB-NH2@PArg, which comprises a precursor molecular (TTB-NH2) and amphipathic polyarginine (PArg) is developed. In TTB-NH2@PArg, PArg serves as both self-assembled nanocarrier for TTB-NH2 and a NO generator. In tumor microenvironment (TME), the TME-specific generation of NO acts as a gas activator, triggering in situ bioorthogonal bond formation that transforms TTB-NH2 into TTB-AZO. This tumor-specific generation of TTB-AZO not only serves as a potential photothermal agent for effective tumor inhibition but also induces fluorescence change that enables real-time monitoring of bioorthogonal activation. This study presents a drug codelivery approach that enables precise and safe control of bioorthogonal activation for anticancer treatment, improving cancer therapy efficacy while minimizing side effects.

Reactive Microneedle Patches with Antibacterial and Dead Bacteria-Trapping Abilities for Skin Infection Treatment

Bacterial skin infections are highly prevalent and pose a significant public health threat. Current strategies are primarily focused on the inhibition of bacterial activation while disregarding the excessive inflammation induced by dead bacteria remaining in the body and the effect of the acidic microenvironment during therapy. In this study, a novel dual-functional MgB2 microparticles integrated microneedle (MgB2 MN) patch is presented to kill bacteria and eliminate dead bacteria for skin infection management. The MgB2 microparticles not only can produce a local alkaline microenvironment to promote the proliferation and migration of fibroblasts and keratinocytes, but also achieve >5 log bacterial inactivation. Besides, the MgB2 microparticles effectively mitigate dead bacteria-induced inflammation through interaction with lipopolysaccharide (LPS). With the incorporation of these MgB2 microparticles, the resultant MgB2 MN patches effectively kill bacteria and capture dead bacteria, thereby mitigating these bacteria-induced inflammation. Therefore, the MgB2 MN patches show good therapeutic efficacy in managing animal bacterial skin infections, including abscesses and wounds. These results indicate that reactive metal borides-integrated microneedle patches hold great promise for the treatment of clinical skin infections.

Development of Biocompatible Cu(I)-Microdevices for Bioorthogonal Uncaging and Click Reactions

Transition-metal-catalyzed bioorthogonal reactions emerged a decade ago as a novel strategy to implement spatiotemporal control over enzymatic functions and pharmacological interventions. The use of this methodology in experimental therapy is driven by the ambition of improving the tolerability and PK properties of clinically-used therapeutic agents. The preclinical potential of bioorthogonal catalysis has been validated in vitro and in vivo with the in situ generation of a broad range of drugs, including cytotoxic agents, anti-inflammatory drugs and anxiolytics. In this article, we report our investigations towards the preparation of solid-supported Cu(I)-microdevices and their application in bioorthogonal uncaging and click reactions. A range of ligand-functionalized polymeric devices and off-on Cu(I)-sensitive sensors were developed and tested under conditions compatible with life. Last, we present a preliminary exploration of their use for the synthesis of PROTACs through CuAAC assembly of two heterofunctional mating units.

A Versatile Cryomicroneedle Patch for Traceable Photodynamic Therapy

Photodynamic therapy (PDT) continues to encounter multifarious hurdles, stemming from the ineffectual preservation and delivery system of photosensitizers, the dearth of imaging navigation, and the antioxidant/hypoxic tumor microenvironment. Herein, a versatile cryomicroneedle patch (denoted as CMN-CCPH) is developed for traceable PDT. The therapeutic efficacy is further amplified by catalase (CAT)-induced oxygen (O2) generation and Cu2+-mediated glutathione (GSH) depletion. The CMN-CCPH is composed of cryomicroneedle (CMN) as the vehicle and CAT-biomineralized copper phosphate nanoflowers (CCP NFs) loaded with hematoporphyrin monomethyl ether (HMME) as the payload. Importantly, the bioactive function of HMME and CAT can be optimally maintained under the protection of CCPH and CMN for a duration surpassing 60 days, leading to bolstered bioavailability and notable enhancements in PDT efficacy. The in vivo visualization of HMME and oxyhemoglobin saturation (sO2) monitored by fluorescence (FL)/photoacoustic (PA) duplex real-time imaging unveils the noteworthy implications of CMN-delivered CCPH for intratumoral enrichment of HMME and O2 with reduced systemic toxicity. This versatile CMN patch demonstrates distinct effectiveness in neoplasm elimination, underscoring its promising clinical prospects.

Critical learning from industrial catalysis for nanocatalytic medicine

Systematical and critical learning from industrial catalysis will bring inspiration for emerging nanocatalytic medicine, but the relevant knowledge is quite limited so far. In this review, we briefly summarize representative catalytic reactions and corresponding catalysts in industry, and then distinguish the similarities and differences in catalytic reactions between industrial and medical applications in support of critical learning, deep understanding, and rational designing of appropriate catalysts and catalytic reactions for various medical applications. Finally, we summarize/outlook the present and potential translation from industrial catalysis to nanocatalytic medicine. This review is expected to display a clear picture of nanocatalytic medicine evolution.

Recent advances in hydrogel microneedle-based biofluid extraction and detection in food and agriculture

Microneedle (MN) technology has been extensively studied for its advantages of minimal invasiveness and user-friendliness. Notably, hydrogel microneedles (HMNs) have garnered considerable attention for biofluid extraction due to its high swelling properties and biocompatibility. This review provides a comprehensive overview of definition, materials, and fabrication methods associated with HMNs. The extraction mechanisms and optimization strategies for enhancing extraction efficiency are summarized. Moreover, particular emphasis is placed on HMN-based biofluid extraction and detection in the domains of food and agriculture, encompassing the detection of small molecules, nucleic acids, and other relevant analytes. Finally, current challenges and possible solutions associated with HMN-based biofluid extraction are discussed.

Nanoparticle-Catalyzed Transamination under Tumor Microenvironment Conditions: A Novel Tool to Disrupt the Pool of Amino Acids and GSSG in Cancer Cells

Catalytic cancer therapy targets cancer cells by exploiting the specific characteristics of the tumor microenvironment (TME). TME-based catalytic strategies rely on the use of molecules already present in the TME. Amino groups seem to be a suitable target, given the abundance of proteins and peptides in biological environments. Here we show that catalytic CuFe2O4 nanoparticles are able to foster transaminations with different amino acids and pyruvate, another key molecule present in the TME. We observed a significant in cellulo decrease in glutamine and alanine levels up to 48 h after treatment. In addition, we found that di- and tripeptides also undergo catalytic transamination, thereby extending the range of the effects to other molecules such as glutathione disulfide (GSSG). Mechanistic calculations for GSSG transamination revealed the formation of an imine between the oxo group of pyruvate and the free -NH2 group of GSSG. Our results highlight transamination as alternative to the existing toolbox of catalytic therapies.

Applications and prospects of microneedles in tumor drug delivery

As drug delivery devices, microneedles are used widely in the local administration of various drugs. Such drug-loaded microneedles are minimally invasive, almost painless, and have high drug delivery efficiency. In recent decades, with advancements in microneedle technology, an increasing number of adaptive, engineered, and intelligent microneedles have been designed to meet increasing clinical needs. This article summarizes the types, preparation materials, and preparation methods of microneedles, as well as the latest research progress in the application of microneedles in tumor drug delivery. This article also discusses the current challenges and improvement strategies in the use of microneedles for tumor drug delivery.

Self-Heating Multistage Microneedle Patch for Topical Therapy of Skin Cancer

Topical therapy is a favored route for treating skin cancers, but remain many challenges, such as low delivery efficiency, limited tumor tissue penetration, and unsatisfactory blood circulation. Here, a self-heating microneedle (MN) patch with multilevel structures, including a dissolvable base for rapid drug release, a degradable tip for sustained drug release, and a self-heating substrate is described. The thermally enhanced drug release performance is validated through both in vitro and in vivo experiments. High tumor therapeutic efficacy can be achieved due to the rapid release of 5-fluorouracil, while the sustained release of thymoquinone endows the MN patch with long-term tumor inhibition ability. It is further demonstrated the feasibility of such an MN patch for in vivo topical therapy of cutaneous squamous cell carcinoma with high efficacy, low side effects, and long-term inhibition of recurrence. This self-heating MN patch holds great promise for potential clinical applications, especially for the treatment of skin cancers.

Enzyme-Mediated Bioorthogonal Cascade Catalytic Reaction for Metabolism Intervention and Enhanced Ferroptosis on Neuroblastoma

It remains a tremendous challenge to explore effective therapeutic modalities against neuroblastoma, a lethal cancer of the sympathetic nervous system with poor prognosis and disappointing treatment outcomes. Considering the limitations of conventional treatment modalities and the intrinsic vulnerability of neuroblastoma, we herein develop a pioneering sequential catalytic therapeutic system that utilizes lactate oxidase (LOx)/horseradish peroxidase (HRP)-loaded amorphous zinc metal-organic framework, named LOx/HRP-aZIF, in combination with a 3-indole-acetic acid (IAA) prodrug. On the basis of abnormal lactate accumulation that occurs in the tumor microenvironment, the cascade reaction of LOx and HRP consumes endogenous glutathione and a reduced form of nicotinamide adenine dinucleotide to achieve the first stage of killing cancer cells via antioxidative incapacitation and electron transport chain interference. Furthermore, the generation of reactive oxygen species induced by HRP and IAA through bioorthogonal catalysis promotes ferritin degradation and lipid peroxidation, ultimately provoking self-enhanced ferroptosis with positive feedback by initiating an endogenous Fenton reaction. This work highlights the superiority of the natural enzyme-dependent cascade and bioorthogonal catalytic reaction, offering a paradigm for synergistically enzyme-based metabolism-ferroptosis anticancer therapy.

Single-Atom Catalysts Mediated Bioorthogonal Modulation of N6-Methyladenosine Methylation for Boosting Cancer Immunotherapy

Bioorthogonal reactions provide a powerful tool to manipulate biological processes in their native environment. However, the transition-metal catalysts (TMCs) for bioorthogonal catalysis are limited to low atomic utilization and moderate catalytic efficiency, resulting in unsatisfactory performance in a complex physiological environment. Herein, sulfur-doped Fe single-atom catalysts with atomically dispersed and uniform active sites are fabricated to serve as potent bioorthogonal catalysts (denoted as Fe-SA), which provide a powerful tool for in situ manipulation of cellular biological processes. As a proof of concept, the N6-methyladensoine (m6A) methylation in macrophages is selectively regulated by the mannose-modified Fe-SA nanocatalysts (denoted as Fe-SA@Man NCs) for potent cancer immunotherapy. Particularly, the agonist prodrug of m6A writer METTL3/14 complex protein (pro-MPCH) can be activated in situ by tumor-associated macrophage (TAM)-targeting Fe-SA@Man, which can upregulate METTL3/14 complex protein expression and then reprogram TAMs for tumor killing by hypermethylation of m6A modification. Additionally, we find the NCs exhibit an oxidase (OXD)-like activity that further boosts the upregulation of m6A methylation and the polarization of macrophages via producing reactive oxygen species (ROS). Ultimately, the reprogrammed M1 macrophages can elicit immune responses and inhibit tumor proliferation. Our study not only sheds light on the design of single-atom catalysts for potent bioorthogonal catalysis but also provides new insights into the spatiotemporal modulation of m6A RNA methylation for the treatment of various diseases.

Controlled Bio-Orthogonal Catalysis Using Nanozyme-Protein Complexes via Modulation of Electrostatic Interactions

Bio-orthogonal chemistry provides a powerful tool for drug delivery systems due to its ability to generate therapeutic agents in situ, minimizing off-target effects. Bio-orthogonal transition metal catalysts (TMCs) with stimuli-responsive properties offer possibilities for controllable catalysis due to their spatial-, temporal-, and dosage-controllable properties. In this paper, we fabricated a stimuli-responsive bio-orthogonal catalysis system based on an enhanced green fluorescent protein (EGFP)-nanozyme (NZ) complex (EGFP-NZ). Regulation of the catalytic properties of the EGFP-NZ complex was directly achieved by modulating the ionic strength of the solution. The dielectric screening introduced by salt ions allows the dissociation of the EGFP-NZ complex, increasing the access of substrate to the active site of the NZs and concomitantly increasing nanozyme activity. The change in catalytic rate of the NZ/EGFP = 1:1 complex was positively correlated with salt concentration from 0 mM to 150 mM.

Self-Metallized Whole Cell Vaccines Prepared by Microfluidics for Bioorthogonally Catalyzed Antitumor Immunotherapy

Tumor whole cell, carrying a complete set of tumor-associated antigens and tumor-specific antigens, has shown great potential in the construction of tumor vaccines but is hindered by the complex engineering means and limited efficacy to cause immunity. Herein, we provided a strategy for the self-mineralization of autologous tumor cells with palladium ions in microfluidic droplets, which endowed the engineered cells with both immune and catalytic functions, to establish a bioorthogonally catalytic tumor whole-cell vaccine. This vaccine showed strong inhibition both in the occurrence and recurrence of tumor by invoking the immediate antitumor immunity and building a long-term immunity.

Nanocatalysts for modulating antitumor immunity: fabrication, mechanisms and applications

Immunotherapy harnesses the inherent immune system in the body to generate systemic antitumor immunity, offering a promising modality for defending against cancer. However, tumor immunosuppression and evasion seriously restrict the immune response rates in clinical settings. Catalytic nanomedicines can transform tumoral substances/metabolites into therapeutic products in situ, offering unique advantages in antitumor immunotherapy. Through catalytic reactions, both tumor eradication and immune regulation can be simultaneously achieved, favoring the development of systemic antitumor immunity. In recent years, with advancements in catalytic chemistry and nanotechnology, catalytic nanomedicines based on nanozymes, photocatalysts, sonocatalysts, Fenton catalysts, electrocatalysts, piezocatalysts, thermocatalysts and radiocatalysts have been rapidly developed with vast applications in cancer immunotherapy. This review provides an introduction to the fabrication of catalytic nanomedicines with an emphasis on their structures and engineering strategies. Furthermore, the catalytic substrates and state-of-the-art applications of nanocatalysts in cancer immunotherapy have also been outlined and discussed. The relationships between nanostructures and immune regulating performance of catalytic nanomedicines are highlighted to provide a deep understanding of their working mechanisms in the tumor microenvironment. Finally, the challenges and development trends are revealed, aiming to provide new insights for the future development of nanocatalysts in catalytic immunotherapy.

Bacterial Flagellum-Drug Nanoconjugates for Carrier-Free Immunochemotherapy

The combination of immunotherapy and chemotherapy to ablate tumors has attracted substantial attention due to the ability to simultaneously elicit antitumor immune responses and trigger direct tumor cell death. However, conventional combinational strategies mainly focus on the employment of drug carriers to deliver immunomodulators, chemotherapeutics, or their combinations, always suffering from complicated preparation and carrier-relevant side effects. Here, the fabrication of bacterial flagellum-drug nanoconjugates (FDNCs) for carrier-free immunochemotherapy is described. FDNCs are simply prepared by attaching chemotherapeutics to amine residues of flagellin through an acid-sensitive and traceless cis-aconityl linker. By virtue of native nanofibrous structure and immunogenicity, bacterial flagella not only show long-term tumor retention and highly efficient cell internalization, but also provoke robust systemic antitumor immune responses. Meanwhile, conjugated chemotherapeutics exhibit an acid-mediated release profile and durable intratumoral exposure, which can induce potent tumor cell inhibition via direct killing. More importantly, this combination is able to augment immunoactivation effects associated with chemotherapy-enabled immunogenic tumor cell death to further enhance antitumor efficacy. By leveraging the innate response of the immune system to pathogens, the conjugation of therapeutic agents with self-adjuvant bacterial flagella provides an alternative approach to develop carrier-free nanotherapeutics for tumor immunochemotherapy.

The Necessity to Investigate In Vivo Fate of Nanoparticle-Loaded Dissolving Microneedles

Transdermal drug delivery systems are rapidly gaining prominence and have found widespread application in the treatment of numerous diseases. However, they encounter the challenge of a low transdermal absorption rate. Microneedles can overcome the stratum corneum barrier to enhance the transdermal absorption rate. Among various types of microneedles, nanoparticle-loaded dissolving microneedles (DMNs) present a unique combination of advantages, leveraging the strengths of DMNs (high payload, good mechanical properties, and easy fabrication) and nanocarriers (satisfactory solubilization capacity and a controlled release profile). Consequently, they hold considerable clinical application potential in the precision medicine era. Despite this promise, no nanoparticle-loaded DMN products have been approved thus far. The lack of understanding regarding their in vivo fate represents a critical bottleneck impeding the clinical translation of relevant products. This review aims to elucidate the current research status of the in vivo fate of nanoparticle-loaded DMNs and elaborate the necessity to investigate the in vivo fate of nanoparticle-loaded DMNs from diverse aspects. Furthermore, it offers insights into potential entry points for research into the in vivo fate of nanoparticle-loaded DMNs, aiming to foster further advancements in this field.

Exploration of the Delivery of Oncolytic Newcastle Disease Virus by Gelatin Methacryloyl Microneedles

Oncolytic Newcastle disease virus is a new type of cancer immunotherapy drug. This paper proposes a scheme for delivering oncolytic viruses using hydrogel microneedles. Gelatin methacryloyl (GelMA) was synthesized by chemical grafting, and GelMA microneedles encapsulating oncolytic Newcastle disease virus (NDV) were prepared by micro-molding and photocrosslinking. The release and expression of NDV were tested by immunofluorescence and hemagglutination experiments. The experiments proved that GelMA was successfully synthesized and had hydrogel characteristics. NDV was evenly dispersed in the allantoic fluid without agglomeration, showing a characteristic virus morphology. NDV particle size was 257.4 ± 1.4 nm, zeta potential was -13.8 ± 0.5 mV, virus titer TCID50 was 107.5/mL, and PFU was 2 × 107/mL, which had a selective killing effect on human liver cancer cells in a dose and time-dependent manner. The NDV@GelMA microneedles were arranged in an orderly cone array, with uniform height and complete needle shape. The distribution of virus-like particles was observed on the surface. GelMA microneedles could successfully penetrate 5% agarose gel and nude mouse skin. Optimal preparation conditions were freeze-drying. We successfully prepared GelMA hydrogel microneedles containing NDV, which could effectively encapsulate NDV but did not detect the release of NDV.

Polarization of macrophages to an anti-cancer phenotype through in situ uncaging of a TLR 7/8 agonist using bioorthogonal nanozymes

Macrophages are plastic cells of the immune system that can be broadly classified as having pro-inflammatory (M1-like) or anti-inflammatory (M2-like) phenotypes. M2-like macrophages are often associated with cancers and can promote cancer growth and create an immune-suppressive tumor microenvironment. Repolarizing macrophages from M2-like to M1-like phenotype provides a crucial strategy for anticancer immunotherapy. Imiquimod is an FDA-approved small molecule that can polarize macrophages by activating toll-like receptor 7/8 (TLR 7/8) located inside lysosomes. However, the non-specific inflammation that results from the drug has limited its systemic application. To overcome this issue, we report the use of gold nanoparticle-based bioorthogonal nanozymes for the conversion of an inactive, imiquimod-based prodrug to an active compound for macrophage re-education from anti- to pro-inflammatory phenotypes. The nanozymes were delivered to macrophages through endocytosis, where they uncaged pro-imiquimod in situ. The generation of imiquimod resulted in the expression of pro-inflammatory cytokines. The re-educated M1-like macrophages feature enhanced phagocytosis of cancer cells, leading to efficient macrophage-based tumor cell killing.

Designer Nanoreactors for Bioorthogonal Catalysis

The evolutionary complexity of compartmentalized biostructures (such as cells and organelles) endows life-sustaining multistep chemical cascades and intricate living functionalities. Relatively, within a very short time span, a synthetic paradigm has resulted in tremendous growth in controlling the materials at different length scales (molecular, nano, micro, and macro), improving mechanistic understanding and setting the design principals toward different compositions, configurations, and structures, and in turn fine-tuning their optoelectronic and catalytic properties for targeted applications. Bioorthogonal catalysis offers a highly versatile toolkit for biochemical modulation and the capability to perform new-to-nature reactions inside living systems, endowing augmented functions. However, conventional catalysts have limitations to control the reactions under physiological conditions due to the hostile bioenvironment. The present account details the development of bioapplicable multicomponent designer nanoreactors (NRs), where the compositions, morphologies, interfacial active sites, and microenvironments around different metal nanocatalysts can be precisely controlled by novel nanospace-confined chemistries. Different architectures of porous, hollow, and open-mouth silica-based nano-housings facilitate the accommodation, protection, and selective access of different nanoscale metal-based catalytic sites. The modular porosity/composition, optical transparency, thermal insulation, and nontoxicity of silica are highly useful. Moreover, large macropores or cavities can also be occupied by enzymes (for chemoenzymatic cascades) and selectivity enhancers (for stimuli-responsive gating) along with the metal nanocatalysts. Further, it is crucial to selectively activate and control catalytic reactions by a remotely operable biocompatible energy source. Integration of highly coupled plasmonic (Au) components having few-nanometer structural features (gaps, cavities, and junctions as electromagnetic hot-spots) endows an opportunity to efficiently harness low-power NIR light and selectively supply energy to the interfacial catalytic sites through localized photothermal and electronic effects. Different plasmonically integrated NRs with customizable plasmonic-catalytic components, cavities inside bilayer nanospaces, and metal-laminated nanocrystals inside hollow silica can perform NIR-/light-induced catalytic reactions in complex media including living cells. In addition, magnetothermia-induced NRs by selective growth of catalytic metals on a pre-installed superparamagnetic iron-oxide core inside a hollow-porous silica shell endowed the opportunity to apply AMF as a bioorthogonal stimulus to promote catalytic reactions. By combining "plasmonic-catalytic" and "magnetic-catalytic" components within a single NR, two distinct reaction steps can be desirably controlled by two energy sources (NIR light and AMF) of distinct energy regimes. The capability to perform multistep organic molecular transformations in harmony with the natural living system will reveal novel reaction schemes for in cellulo synthesis of active drug and bioimaging probes. Well-designed nanoscale discrete architectures of NRs can facilitate spatiotemporal control over abiotic chemical synthesis without adversely affecting the cell viability. However, in-depth understanding of heterogeneous surface catalytic reactions, rate induction mechanisms, selectivity control pathways, and targeted nanobio interactions is necessary. The broad field of biomedical engineering can hugely benefit from the aid of novel nanomaterials with chemistry-based designs and the synthesis of engineered NRs performing unique bioorthogonal chemistry functions.

MOFs Modulate Copper Trafficking in Tumor Cells for Bioorthogonal Therapy

In situ drug synthesis using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has attracted considerable attention in tumor therapy because of its satisfactory effectiveness and reduced side-effects. However, the exogenous addition of copper catalysts can cause cytotoxicity and has hampered biomedical applications in vivo. Here, we design and synthesize a metal-organic framework (MOF) to mimic copper chaperone, which can selectively modulate copper trafficking for bioorthogonal synthesis with no need of exogenous addition of copper catalysts. Like copper chaperones, the prepared ZIF-8 copper chaperone mimics specifically bind copper ions through the formation of coordination bonds. Moreover, the copper is unloaded under the acidic environment due to the dissipation of the coordination interactions between metal ions and ligands. In this way, the cancer cell-targeted copper chaperone mimics can selectively transport copper ions into cells. Regulation of intracellular copper trafficking may inspire constructing bioorthogonal catalysis system with reduced metal cytotoxicity in live cells.

Dipeptide coacervates as artificial membraneless organelles for bioorthogonal catalysis

Artificial organelles can manipulate cellular functions and introduce non-biological processes into cells. Coacervate droplets have emerged as a close analog of membraneless cellular organelles. Their biomimetic properties, such as molecular crowding and selective partitioning, make them promising components for designing cell-like materials. However, their use as artificial organelles has been limited by their complex molecular structure, limited control over internal microenvironment properties, and inherent colloidal instability. Here we report the design of dipeptide coacervates that exhibit enhanced stability, biocompatibility, and a hydrophobic microenvironment. The hydrophobic character facilitates the encapsulation of hydrophobic species, including transition metal-based catalysts, enhancing their efficiency in aqueous environments. Dipeptide coacervates carrying a metal-based catalyst are incorporated as active artificial organelles in cells and trigger an internal non-biological chemical reaction. The development of coacervates with a hydrophobic microenvironment opens an alternative avenue in the field of biomimetic materials with applications in catalysis and synthetic biology.

Continuous Phase Regulation of a Pd-Te Hexagonal Nanoplate Library

Phase regulation of noble metal-based nanomaterials provides a promising strategy for boosting the catalytic performance. However, realizing the continuous phase modulation in two-dimensional structures and unveiling the relevant structure-performance relationship remain significant challenges. In this work, we present the first example of continuous phase modulation in a library of Pd-Te hexagonal nanoplates (HNPs) from cubic-phase Pd4Te, rhombohedral-phase Pd20Te7, rhombohedral-phase Pd8Te3, and hexagonal-phase PdTe to hexagonal-phase PdTe2. Notably, the continuous phase regulation of the well-defined Pd-Te HNPs enables the successful modulation of the distance between adjacent Pd active sites, triggering an exciting way for tuning the relevant catalytic reactions intrinsically. The proof-of-concept oxygen reduction reaction (ORR) experiment shows a Pd-Pd distance-dependent ORR performance, where the hexagonal-phase PdTe HNPs present the best electrochemical performance in ORR (mass activity and specific activity of 1.02 A mg-1Pd and 1.83 mA cm-2Pd at 0.9 V vs RHE). Theoretical investigation reveals that the increased Pd-Pd distance relates to the weak *OH adsorption over Pd-Te HNPs, thus contributing to the remarkable ORR activity of PdTe HNPs. This work advances the phase-controlled synthesis of noble metal-based nanostructures, which gives huge impetus to the design of high-efficiency nanomaterials for diverse applications.

Designing Bioorthogonal Reactions for Biomedical Applications

Bioorthogonal reactions are a class of chemical reactions that can be carried out in living organisms without interfering with other reactions, possessing high yield, high selectivity, and high efficiency. Since the first proposal of the conception by Professor Carolyn Bertozzi in 2003, bioorthogonal chemistry has attracted great attention and has been quickly developed. As an important chemical biology tool, bioorthogonal reactions have been applied broadly in biomedicine, including bio-labeling, nucleic acid functionalization, drug discovery, drug activation, synthesis of antibody-drug conjugates, and proteolysis-targeting chimeras. Given this, we summarized the basic knowledge, development history, research status, and prospects of bioorthogonal reactions and their biomedical applications. The main purpose of this paper is to furnish an overview of the intriguing bioorthogonal reactions in a variety of biomedical applications and to provide guidance for the design of novel reactions to enrich bioorthogonal chemistry toolkits.

A Gene-Editable Palladium-Based Bioorthogonal Nanoplatform Facilitates Macrophage Phagocytosis for Tumor Therapy

Macrophage phagocytosis of tumor cells has emerged as an attractive strategy for tumor therapy. Nevertheless, immunosuppressive M2 macrophages in the tumor microenvironment and the high expression of anti-phagocytic signals from tumor cells impede therapeutic efficacy. To address these issues and improve the management of malignant tumors, in this study we developed a gene-editable palladium-based bioorthogonal nanoplatform, consisting of CRISPR/Cas9 gene editing system-linked Pd nanoclusters, and a hyaluronic acid surface layer (HBPdC). This HBPdC nanoplatform exhibited satisfactory tumor-targeting efficiency and triggered Fenton-like reactions in the tumor microenvironment to generate reactive oxygen species for chemodynamic therapy and macrophage M1 polarization, which directly eliminated tumor cells, and stimulated the antitumor response of macrophages. HBPdC could reprogram tumor cells through gene editing to reduce the expression of CD47 and adipocyte plasma membrane-associated protein, thereby promoting their recognition and phagocytosis by macrophages. Moreover, HBPdC induced the activation of sequestered prodrugs via bioorthogonal catalysis, enabling chemotherapy and thereby enhancing tumor cell death. Importantly, the Pd nanoclusters of HBPdC were sufficiently cleared through basic metabolic pathways, confirming their biocompatibility and biosafety. Therefore, by promoting macrophage phagocytosis, the HBPdC system developed herein represents a highly promising antitumor toolset for cancer therapy applications.

Target-Specific Bioorthogonal Reactions for Precise Biomedical Applications

Bioorthogonal chemistry is a promising toolbox for dissecting biological processes in the native environment. Recently, bioorthogonal reactions have attracted considerable attention in the medical field for treating diseases, since this approach may lead to improved drug efficacy and reduced side effects via in situ drug synthesis. For precise biomedical applications, it is a prerequisite that the reactions should occur in the right locations and on the appropriate therapeutic targets. In this minireview, we highlight the design and development of targeted bioorthogonal reactions for precise medical treatment. First, we compile recent strategies for achieving target-specific bioorthogonal reactions. Further, we emphasize their application for the precise treatment of different therapeutic targets. Finally, a perspective is provided on the challenges and future directions of this emerging field for safe, efficient, and translatable disease treatment.

Regulating Size and Charge of Liposomes in Microneedles to Enhance Intracellular Drug Delivery Efficiency in Skin for Psoriasis Therapy

The stratum corneum (SC) and cell membrane are two major barriers that hinder the therapeutic outcomes of transdermal drug delivery for the treatment of skin diseases. While microneedles (MNs) can efficiently penetrate the SC to deliver nanomedicines, the optimization of physicochemical properties of nanomedicines in MNs to enhance their in vivo cellular delivery efficiency remains unclear. Here, how the size and surface charge of drug-loaded liposomes in MNs influence the retention time and cellular delivery in psoriatic skin is systematically investigated. The results indicate that while 100 nm negatively-charged liposomes in MNs show higher cellular uptake in vitro, 250 and 450 nm liposomes could enhance skin retention and the long-term in vivo cellular delivery efficiency of drugs. Moreover, 250 nm cationic liposomes with a stronger positive charge show an extraordinarily long skin retention time of 132 h and significantly higher in vivo cellular internalization. In the treatment study, dexamethasone (dex)-loaded cationic liposomes-integrated MNs show better therapeutic outcomes than dex-loaded anionic liposomes-integrated MNs in a psoriasis-like animal model. The design principles of liposomes in MN drug delivery systems explored in the study hold the potential for enhancing the therapeutic outcomes of psoriasis and are instrumental for successful translation.

Bioorthogonal chemistry for prodrug activation in vivo

Prodrugs have emerged as a major strategy for addressing clinical challenges by improving drug pharmacokinetics, reducing toxicity, and enhancing treatment efficacy. The emergence of new bioorthogonal chemistry has greatly facilitated the development of prodrug strategies, enabling their activation through chemical and physical stimuli. This "on-demand" activation using bioorthogonal chemistry has revolutionized the research and development of prodrugs. Consequently, prodrug activation has garnered significant attention and emerged as an exciting field of translational research. This review summarizes the latest advancements in prodrug activation by utilizing bioorthogonal chemistry and mainly focuses on the activation of small-molecule prodrugs and antibody-drug conjugates. In addition, this review also discusses the opportunities and challenges of translating these advancements into clinical practice.

A tumor microenvironment-responsive microneedle patch for chemodynamic therapy of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common malignant tumors of the head and neck, and this disease has become a threat to public health due to its poor prognosis and high fatality rate. Chemodynamic therapy (CDT) is an emerging oncology treatment based on the Fenton reaction. However, the lack of endogenous hydrogen peroxide (H2O2) in tumor cells and the high concentration of glutathione (GSH) that depletes toxic hydroxyl radicals (·OH) significantly impair the efficacy of CDT. Here, we developed a polyvinyl alcohol (PVA)-based soluble microneedle patch (denoted as Fe3O4 + VC-MN) loaded with Fe3O4 nanoparticles (NPs) and vitamin C (VC) for the effective treatment of OSCC. When Fe3O4 + VC-MNs are inserted into the OSCC tissue, the Fe3O4 NPs and VC loaded in the tip of the needle are released in a targeted manner. After VC is converted into oxidized vitamin C (DHA), it can consume GSH in tumor cells and generate sufficient intracellular H2O2in situ. Moreover, by virtue of their peroxidase-like activity, Fe3O4 NPs can induce the generation of lethal ·OH through the Fenton reaction with the aforementioned H2O2, leading to tumor cell ferroptosis and apoptosis, thus achieving CDT. Collectively, this functional microneedle patch provides a more efficient and minimally invasive targeted drug delivery solution for the treatment of OSCC.

Ultrarapid-Acting Microneedles for Immediate Delivery of Biotherapeutics

Subcutaneous (SC) injection is a common administration route for rapid and efficient delivery of biotherapeutics. However, syringe-based injections usually require professional assistance and are associated with pain and potential risks of infections, thus leading to undesired patient compliance and poor life quality. Herein, this work presents an ultrarapid-acting microneedle (URA-MN) patch for immediate transdermal delivery of therapeutics in a minimally invasive manner. Effervescent agents are incorporated into the tip of URA-MN for rapid generation of CO2 bubbles upon insertion into the skin, immediately powering the biotherapeutics release within a few minutes. The release kinetics of diverse agents including liraglutide (LRT), insulin, and heparin from the URA-MN patches are evaluated in three different mouse models, and the rapid release of biotherapeutics and potent therapeutic effects are achieved with only 5 min administration. Noteworthily, attributed to the short application duration and negligible residuals of MN matrix remaining in the skin, the URA-MN patch shows desirable biocompatibility after six-week administration.

Preparation, characterization, and evaluation of the antitumor effect of kaempferol nanosuspensions

Kaempferol (KAE) is a naturally occurring flavonoid compound with antitumor activity. However, the low aqueous solubility, poor chemical stability, and suboptimal bioavailability greatly restrict its clinical application in cancer therapy. To address the aforementioned limitations and augment the antitumor efficacy of KAE, we developed a kaempferol nanosuspensions (KAE-NSps) utilizing D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as a stabilizing agent, screened the optimal preparation process, and conducted a comprehensive investigation of their fundamental properties as well as the antitumor effects in the study. The findings indicated that the particle size was 186.6 ± 2.6 nm of the TPGS-KAE-NSps optimized, the shape of which was fusiform under the transmission electron microscope. The 2% (w/v) glucose was used as the cryoprotectant for TPGS-KAE-NSps, whose drug loading content was 70.31 ± 2.11%, and the solubility was prominently improved compared to KAE. The stability and biocompatibility of TPGS-KAE-NSps were favorable and had a certain sustained release effect. Moreover, TPGS-KAE-NSps clearly seen to be taken in the cytoplasm exhibited a stronger cytotoxicity and suppression of cell migration, along with increased intracellular ROS production and higher apoptosis rates compared to KAE in vitro cell experiments. In addition, TPGS-KAE-NSps had a longer duration of action in mice, significantly improved bioavailability, and showed a stronger inhibition of tumor growth (the tumor inhibition rate of high dose intravenous injection group was 68.9 ± 1.46%) than KAE with no obvious toxicity in 4T1 tumor-bearing mice. Overall, TPGS-KAE-NSps prepared notably improved the defect and the antitumor effects of KAE, making it a promising nanodrug delivery system for KAE with potential applications as a clinical antitumor drug.

Progress in controllable bioorthogonal catalysis for prodrug activation

Bioorthogonal catalysis, a class of catalytic reactions that are mediated by abiotic metals and proceed in biological environments without interfering with native biochemical reactions, has gained ever-increasing momentum in prodrug delivery over the past few decades. Albeit great progress has been attained in developing new bioorthogonal catalytic reactions and optimizing the catalytic performance of transition metal catalysts (TMCs), the use of TMCs to activate chemotherapeutics at the site of interest in vivo remains a challenging endeavor. To translate the bioorthogonal catalysis-mediated prodrug activation paradigm from flasks to animals, TMCs with targeting capability and stimulus-responsive behavior have been well-designed to perform chemical transformations in a controlled manner within highly complex biochemical systems, rendering on-demand drug activation to mitigate off-target toxicity. Here, we review the recent advances in the development of controllable bioorthogonal catalysis systems, with an emphasis on different strategies for engineering TMCs to achieve precise control over prodrug activation. Furthermore, we outline the envisaged challenges and discuss future directions of controllable bioorthogonal catalysis for disease therapy.

Flower-like porous BCN assembled by nanosheets for paclitaxel delivery

Developing smart drug delivery systems has become a feasible solution to overcome the challenges in cancer chemotherapeutics. In this work, porous boron carbon nitride (ZBCN) nanomaterials with flower-like structures assembled with BCN nanosheets were synthesized by using ZIF-L as a template. The rich hydroxyl groups on the BCN surfaces make it highly dispersible and stable in aqueous solutions. Additionally, ZBCN exhibits stable photoluminescence properties that can be utilized for cellular uptake and tracking of drug delivery. Furthermore, the flower-like ZBCN structure contributes to a large specific surface area of up to 340 m2 g-1 and a pore volume of 1.03 cm3 g-1; and the presence of rich macropores results in a high drug loading capacity of 116 wt% for paclitaxel. In vitro and in vivo anticancer experiments demonstrated that ZBCN exhibits excellent performance in delivering anticancer drugs, with in vivo tumor inhibition of 58%. This study presents a novel template method for preparing porous BCN nanomaterials, offering a promising platform for high-performance anticancer drug delivery.

A Nanobody-Bioorthogonal Catalyst Conjugate Triggers Spatially Confined Prodrug Activation for Combinational Chemo-immunotherapy

Checkpoint inhibitors have been used with chemotherapy to improve antitumor efficacy. However, overcoming the immunosuppressive effect of chemotherapeutics remains a challenge. We report a nanobody-catalyst conjugate Ru-PD-L1 by fusing a ruthenium catalyst to an anti-PD-L1 nanobody. After administration of Ru-PD-L1 and a doxorubicin (DOX) prodrug, Ru-PD-L1 disrupts the PD-L1/PD-1 interaction and catalyzes the uncaging of the DOX prodrug. The spatially confined release of DOX reduces its systemic toxicity and leads to immunogenic cell death (ICD). The induced ICD triggers antitumor immune responses, which are further amplified by PD-L1 blockade to elicit synergistic chemo-immunotherapy, substantially increasing the number of tumor-infiltrating T-cells by 49.7% compared with the controls, thereby exhibiting high antitumor activity and low cytotoxicity in murine models. The combinational treatment could inhibit the growth of mice tumors by 67.7% compared to the control group. This combinational approach circumvents the negative immunogenic effects of chemotherapeutics and provides a potential chemo-immunotherapy strategy for human cancer treatment.

Spatiotemporal Catalytic Nanozymes Microneedle Patches with Opposite Properties for Wound Management

Reactive oxygen species (ROS)-mediated biological catalysis involves serial programmed enzymatic reactions and plays an important part against infectious diseases; while the spatiotemporal control of catalytic treatment to break the limitations of the disease microenvironment is challenging. Here, a novel spatiotemporal catalytic microneedles patch (CMSP-MNs) integrated with dual-effective Cu2 MoS4 (CMS) and polydopamine (PDA) nanoparticles (NPs) for breaking microenvironment restrictions to treat wound infections is designed. Since CMS NPs are loaded in the needles, CMSP-MNs can catalytically generate diverse ROS to cause effective bacterial inactivation during bacterial infection process. Besides, PDA NPs are encapsulated in the backing layer, which facilitate ROS elimination and oxygen production for solving hypoxic problems in wound microenvironment and alleviating the expression of inflammatory factors during the inflammation process. Based on these features, it is demonstrated through cell and animal experiments that these nanozymes-integrated MNs patches can realize selective regulation of ROS level with bacterial inactivation and inflammatory treatment, resulting in minimized side effects of over-production ROS and effective anti-infected treatment. It is believed that the presented MNs can provide a new therapeutic strategy with spatiotemporal adjustable catalytic properties in biomedical areas.

Targeted delivery of PROTAC-based prodrug activated by bond-cleavage bioorthogonal chemistry for microneedle-assisted cancer therapy

Proteolysis-targeting chimera (PROTAC) is emerging as a new strategy to degrade target proteins in a precise way by taking advantage of the cellular ubiquitin-proteasome system. However, the potential cytotoxicity of PROTAC should be avoided to mitigate the off-target degradation of proteins in healthy tissues or cells. To address this issue, we herein present a strategy to cage a PROTAC with 4-(vinyloxy) benzyl carbonate (MZ1-O), which can be eliminated through a 3,6-dimethyl-1,2,4,5-tetrazine (Tz)-mediated inverse electron-demand Diels-Alder (iEDDA) reaction to generate a BRD4 (bromodomain-containing protein 4) degrader, MZ1. We further propose a dissolvable microneedle-assisted strategy for site-specific activation of MZ1-O that is delivered by a targeted delivery vector through systemic route in vivo, and demonstrate such a bioorthogonal strategy is efficient and precise for tumor treatment. Our study suggests that the bioorthogonal activation of PROTAC-based prodrug offers a highly specific and precise approach for cancer therapy.

Local Drug Delivery Techniques for Triggering Immunogenic Cell Death

Immunogenic cell death (ICD), a dying state of the cells, encompasses the changes in the conformations of cell surface and the release of damage-associated molecular patterns, which could initiate an adaptive immune response by stimulating the dendritic cells to present antigens to T cells. Advancements in biomaterials, nanomedicine, and micro- and nano-technologies have facilitated the development of effective ICD inducers, but the potential toxicity of these vesicles encountered in drug delivery via intravenous administration hampers their further application. As alternatives, the local drug delivery systems have gained emerging attention due to their ability to prolong the retention of high payloads at the lesions, sequester drugs from harsh environments, overcome biological barriers to exert optimal efficacy, and minimize potential side effects to guarantee bio-safety. Herein, a brief overview of the local drug delivery techniques used for ICD inducers is provided, explaining how these techniques broaden, alter, and enhance the therapeutic capability while circumventing systemic toxicity at the same time. The historical context and prominent examples of the local administration of ICD inducers are introduced. The complexities, potential pitfalls, and opportunities for local drug delivery techniques in cancer immunotherapy are also discussed.

An inflammation-responsive double-layer microneedle patch for recurrent atopic dermatitis therapy

Seeking a potent therapeutic strategy for alleviating atopic dermatitis (AD) attack and preventing its recurrence is highly desired but remains challenging in clinical practice. Here, we propose an inflammation-responsive double-layer microneedle (IDMN) patch in situ delivering VD3 for recurrent AD therapy. IDMN comprises the backing layer part and the double-layer microneedle part, in which the inner layer is gelatin methacryloyl (GelMA) loaded with VD3 while the outer layer is composed of hyaluronic acid (HA). Introduction of the HA backing layer and outer layer around the GelMA tips can not only provide sufficient mechanical strength to penetrate into hardened AD skin with minimal invasiveness, but also exert a strong moisturizing effect after being rapidly dissolved. The inner layer of GelMA is degraded by the matrix metalloproteinase (MMP) in a dose dependent manner, which is secreted according to the disease progression of AD. The responsive degradation of GelMA tips result in corresponding release of VD3 to treat AD, triggering negative feedback against GelMA degradation. The IDMN administration on AD-bearing mice reveals efficient "curing" performances (including suppress erythema, scaling and lichenification, reduce epidermal thickness, inhibit mast cells infiltration, and down-regulate inflammatory factor secretion), which are basically realized through synergistic effect of the released VD3 and the dissolved HA molecules. Importantly, the residual tips of IDMN with VD3 are retained in the skin after the first AD relief, showing promising "warning" ability to inhibit the recurrence of AD. Hence, the developed IDMN patch is expected to be one of the excellent candidates for AD therapy and other relapsing diseases in clinical fields.

Recent progress of micro/nanomotors to overcome physiological barriers in the gastrointestinal tract

Oral administration is a convenient administration route for gastrointestinal disease therapy with good patient compliance. But the nonspecific distribution of the oral drugs may cause serious side effects. In recent years, oral drug delivery systems (ODDS) have been applied to deliver the drugs to the gastrointestinal disease sites with decreased side effects. However, the delivery efficiency of ODDS is tremendously limited by physiological barriers in the gastrointestinal sites, such as the long and complex gastrointestinal tract, mucus layer, and epithelial barrier. Micro/nanomotors (MNMs) are micro/nanoscale devices that transfer various energy sources into autonomous motion. The outstanding motion characteristics of MNMs inspired the development of targeted drug delivery, especially the oral drug delivery. However, a comprehensive review of oral MNMs for the gastrointestinal diseases therapy is still lacking. Herein, the physiological barriers of ODDS were comprehensively reviewed. Afterward, the applications of MNMs in ODDS for overcoming the physiological barriers in the past 5 years were highlighted. Finally, future perspectives and challenges of MNMs in ODDS are discussed as well. This review will provide inspiration and direction of MNMs for the therapy of gastrointestinal diseases, pushing forward the clinical application of MNMs in oral drug delivery.

Bioorthogonal Disruption of Pyroptosis Checkpoint for High-Efficiency Pyroptosis Cancer Therapy

Pyroptosis is an inflammatory form of programmed cell death that holds great promise in cancer therapy. However, autophagy as the crucial pyroptosis checkpoint and the self-protective mechanism of cancer cells significantly weakens the therapeutic efficiency. Here, a bioorthogonal pyroptosis nanoregulator is constructed to induce pyroptosis and disrupt the checkpoint, enabling high-efficiency pyroptosis cancer therapy. The nanoregulator allows the in situ synthesis and accumulation of the photosensitizer PpIX in the mitochondria of cancer cells to directly produce mitochondrial ROS, thus triggering pyroptosis. Meanwhile, the in situ generated autophagy inhibitor via palladium-catalyzed bioorthogonal chemistry can disrupt the pyroptosis checkpoint to boost the pyroptosis efficacy. With the biomimetic cancer cell membrane coating, this platform for modulating pyroptosis presents specificity to cancer cells and poses no harm to normal tissue, resulting in a highly efficient and safe antitumor treatment. To our knowledge, this is the first report on a disrupting intrinsic protective mechanism of cancer cells for tumor pyroptosis therapy. This work highlights that autophagy as a checkpoint plays a key regulative role in pyroptosis therapy, which would motivate the future design of therapeutic regimens.

Scarless wound healing programmed by core-shell microneedles

Effective reprogramming of chronic wound healing remains challenging due to the limited drug delivery efficacy hindered by physiological barriers, as well as the inappropriate dosing timing in distinct healing stages. Herein, a core-shell structured microneedle array patch with programmed functions (PF-MNs) is designed to dynamically modulate the wound immune microenvironment according to the varied healing phases. Specifically, PF-MNs combat multidrug-resistant bacterial biofilm at the early stage via generating reactive oxygen species (ROS) under laser irradiation. Subsequently, the ROS-sensitive MN shell gradually degrades to expose the MN core component, which neutralizes various inflammatory factors and promotes the phase transition from inflammation to proliferation. In addition, the released verteporfin inhibits scar formation by blocking Engrailed-1 (En1) activation in fibroblasts. Our experiments demonstrate that PF-MNs promote scarless wound repair in mouse models of both acute and chronic wounds, and inhibit the formation of hypertrophic scar in rabbit ear models.

Microneedle-mediated treatment for superficial tumors by combining multiple strategies

Superficial tumors are still challenging to overcome due to the high risk and toxicity of surgery and conventional chemotherapy. Microneedles (MNs) are widely used in the treatment of superficial skin tumors (SST) due to the high penetration rate of the stratum corneum (SC), excellent biocompatibility, simple preparation process, high patient compliance, and minimal invasion. Most importantly, MNs can provide not only efficient and rarely painful delivery carriers, but also combine multi-model strategies with photothermal therapy (PTT), immunotherapy, and gene therapy for synergistic efficacy. To promote an in-depth understanding of their superiorities, this paper systematically summarized the latest application progress of MNs in the treatment of SST by delivering various types of photosensitizers, immune signal molecules, genes, and chemotherapy drugs. Just as important, the advantages, limitations, and drug release mechanisms of MNs based on different materials are introduced in the paper. In addition, the application of MN technology to clinical practice is the ultimate goal of all the work. The obstacles and possible difficulties in expanding the production of MNs and achieving clinical transformation are briefly discussed in this paper. To be anticipated, our work will provide new insights into the precise and rarely painful treatment of SST in the future.

Bioinspired Adaptable Indwelling Microneedles for Treatment of Diabetic Ulcers

Microneedles provide an effective strategy for transdermal drug delivery. Many endeavors have been devoted to developing smart microneedles that can respond to and interact with pathophysiological environments. Here, novel bioinspired adaptable indwelling microneedles with therapeutic exosome encapsulation are presented for diabetic wound healing by a combined fabrication strategy of template replication and 3D transfer printing. Such microneedles are composed of mesenchymal stem cell (MSC)-exosomes-encapsulated adjustable poly(vinyl alcohol) (PVA) hydrogel needle tips and detachable 3M medical tape supporting substrate. As the mechanical strength of the PVA hydrogel is ionically responsive due to Hofmeister effects, the hardness of the resultant microneedle tips can be upregulated by sulfate ions to ensure skin penetration and be softened by nitrate ions after tip-substrate detachment to adapt to the surrounding tissue and release exosomes. Because the MSC-exosomes can effectively activate fibroblasts, vascular endothelial cells, and macrophages, the indwelling microneedles are demonstrated with the function of promoting tissue regeneration and diabetic wound healing in full-thickness cutaneous wounds of diabetic rat models. These features indicate that the bioinspired adaptable indwelling microneedles are with practical values and clinical prospects in tissue and wound regeneration.

Expanding Transition Metal-Mediated Bioorthogonal Decaging to Include C-C Bond Cleavage Reactions

The ability to control the activation of prodrugs by transition metals has been shown to have great potential for controlled drug release in cancer cells. However, the strategies developed so far promote the cleavage of C-O or C-N bonds, which limits the scope of drugs to only those that present amino or hydroxyl groups. Here, we report the decaging of an ortho-quinone prodrug, a propargylated β-lapachone derivative, through a palladium-mediated C-C bond cleavage. The reaction's kinetic and mechanistic behavior was studied under biological conditions along with computer modeling. The results indicate that palladium (II) is the active species for the depropargylation reaction, activating the triple bond for nucleophilic attack by a water molecule before the C-C bond cleavage takes place. Palladium iodide nanoparticles were found to efficiently trigger the C-C bond cleavage reaction under biocompatible conditions. In drug activation assays in cells, the protected analogue of β-lapachone was activated by nontoxic amounts of nanoparticles, which restored drug toxicity. The palladium-mediated ortho-quinone prodrug activation was further demonstrated in zebrafish tumor xenografts, which resulted in a significant anti-tumoral effect. This work expands the transition-metal-mediated bioorthogonal decaging toolbox to include cleavage of C-C bonds and payloads that were previously not accessible by conventional strategies.

Bioorthogonal nanozymes for breast cancer imaging and therapy

Bioorthogonal catalysis via transition metal catalysts (TMCs) enables the generation of therapeutics locally through chemical reactions not accessible by biological systems. This localization can enhance the efficacy of anticancer treatment while minimizing off-target effects. The encapsulation of TMCs into nanomaterials generates "nanozymes" to activate imaging and therapeutic agents. Here, we report the use of cationic bioorthogonal nanozymes to create localized "drug factories" for cancer therapy in vivo. These nanozymes remained present at the tumor site at least seven days after a single injection due to the interactions between cationic surface ligands and negatively charged cell membranes and tissue components. The prodrug was then administered systemically, and the nanozymes continuously converted the non-toxic molecules into active drugs locally. This strategy substantially reduced the tumor growth in an aggressive breast cancer model, with significantly reduced liver damage compared to traditional chemotherapy.