Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

H2O2-triggered CO release based on porphyrinic covalent organic polymers for photodynamic/gas synergistic therapy

A novel H2O2-responsive carbon monoxide nanogenerator was designed by effectively encapsulating a manganese carbonyl prodrug into porphyrinic covalent organic polymers for realizing the combined CO gas and photodynamic therapy under near infrared light irradiation.

Strategies to address key challenges of metallacycle/metallacage-based supramolecular coordination complexes in biomedical applications

Owing to their capacity for dynamically linking two or more functional molecules, supramolecular coordination complexes (SCCs), exemplified by two-dimensional (2D) metallacycles and three-dimensional (3D) metallacages, have gained increasing significance in biomedical applications. However, their inherent hydrophobicity and self-assembly driven by heavy metal ions present common challenges in their applications. These challenges can be overcome by enhancing the aqueous solubility and in vivo circulation stability of SCCs, alongside minimizing their side effects during treatment. Addressing these challenges is crucial for advancing the fundamental research of SCCs and their subsequent clinical translation. In this review, drawing on extensive contemporary research, we offer a thorough and systematic analysis of the strategies employed by SCCs to surmount these prevalent yet pivotal obstacles. Additionally, we explore further potential challenges and prospects for the broader application of SCCs in the biomedical field.

Propelling Multi-Modal Therapeutics of PEEK Implants through the Power of NO evolving Covalent Organic Frameworks (COFs)

The design and fabrication of NO-evolving core-shell nanoparticles (denoted as NC@Fe), comprised of BNN6-laden COF@Fe3 O4 nanoparticles, are reported. This innovation extends to the modification of 3D printed polyetheretherketone scaffolds with NC@Fe, establishing a pioneering approach to multi-modal bone therapy tailored to address complications such as device-associated infections and osteomyelitis. This work stands out prominently from previous research, particularly those relying on the use of antibiotics, by introducing a bone implant capable of simultaneous NO gas therapy and photothermal therapy (PPT). Under NIR laser irradiation, the Fe3 O4 NP core (photothermal conversion agent) within NC@Fe absorbs photoenergy and initiates electron transfer to the loaded NO donor (BNN6), resulting in controlled NO release. The additional heat generated through photothermal conversion further propels the NC@Fe nanoparticles, amplifying the therapeutic reach. The combined effect of NO release and PPT enhances the efficacy in eradicating bacteria over a more extensive area around the implant, presenting a distinctive solution to conventional challenges. Thorough in vitro and in vivo investigations validate the robust potential of the scaffold in infection control, osteogenesis, and angiogenesis, emphasizing the timeliness of this unique solution in managing complicated bone related infectious diseases.

Covalent Organic Frameworks: Opportunities for Rational Materials Design in Cancer Therapy

Nanomedicines are extensively used in cancer therapy. Covalent organic frameworks (COFs) are crystalline organic porous materials with several benefits for cancer therapy, including porosity, design flexibility, functionalizability, and biocompatibility. This review examines the use of COFs in cancer therapy from the perspective of reticular chemistry and function-oriented materials design. First, the modification sites and functionalization methods of COFs are discussed, followed by their potential as multifunctional nanoplatforms for tumor targeting, imaging, and therapy by integrating functional components. Finally, some challenges in the clinical translation of COFs are presented with the hope of promoting the development of COF-based anticancer nanomedicines and bringing COFs closer to clinical trials.

Covalent-Organic Framework-Based Materials in Theranostic Applications: Insights into Their Advantages and Challenges

Nanomedicine has been essential in bioimaging and cancer therapy in recent years. Nanoscale covalent-organic frameworks (COFs) have been growing as an adequate classification of biomedical nanomaterials with practical application prospects because of their increased porosity, functionality, and biocompatibility. The high sponginess of COFs enables the incorporation of distinct imaging and therapeutic mechanisms with a better loading efficiency. Nevertheless, preliminary biocompatibility limits their possibility for clinical translation. Thus, cutting-edge nanomaterials with high biocompatibility and improved therapeutic efficiency are highly expected to fast-track the clinical translation of nanomedicines. The inherent effects of nanoscale COFs, such as proper size, modular pore geometry and porosity, and specific postsynthetic transformation through simple organic changes, make them particularly appealing for prospective nanomedicines. The organic building blocks of COFs may also be postmodified for particular binding to biomarkers. The exceptional features of COFs cause them to be an encouraging nanocarrier for bioimaging and therapeutic applications. In this review, we have systematically discussed the advances of COFs in the field of theranostics by providing essential features of COFs along with their synthetic methods. Further, the applications of COFs in the field of theranostics (such as drug delivery systems, photothermal, and photodynamic therapy) are discussed in detail with the help of available literature to date. Furthermore, the advantages of COFs over other materials for therapeutics and drug delivery are discussed. Finally, the review concludes with potential future COF applications in the theranostic field.

Comprehensive Insights and Advancements in Gel Catalysts for Electrochemical Energy Conversion

Continuous worldwide demands for more clean energy urge researchers and engineers to seek various energy applications, including electrocatalytic processes. Traditional energy-active materials, when combined with conducting materials and non-active polymeric materials, inadvertently leading to reduced interaction between their active and conducting components. This results in a drop in active catalytic sites, sluggish kinetics, and compromised mass and electronic transport properties. Furthermore, interaction between these materials could increase degradation products, impeding the efficiency of the catalytic process. Gels appears to be promising candidates to solve these challenges due to their larger specific surface area, three-dimensional hierarchical accommodative porous frameworks for active particles, self-catalytic properties, tunable electronic and electrochemical properties, as well as their inherent stability and cost-effectiveness. This review delves into the strategic design of catalytic gel materials, focusing on their potential in advanced energy conversion and storage technologies. Specific attention is given to catalytic gel material design strategies, exploring fundamental catalytic approaches for energy conversion processes such as the CO2 reduction reaction (CO2RR), oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and more. This comprehensive review not only addresses current developments but also outlines future research strategies and challenges in the field. Moreover, it provides guidance on overcoming these challenges, ensuring a holistic understanding of catalytic gel materials and their role in advancing energy conversion and storage technologies.

Glowing Octopus-Inspired Nanomachine: A Versatile Aptasensor for Efficient Capture, Imaging, Separation, and NIR-Triggered Release of Cancer Cells

The separation and analysis of circulating tumor cells (CTCs) in liquid biopsy significantly facilitated clinical cancer diagnosis and personalized therapy. However, current methods face challenges in simultaneous efficient capturing, separation, and imaging of CTCs, and most of the devices cannot be reused/regenerated. We present here an innovative glowing octopus-inspired nanomachine (GOIN), capable of capturing, imaging, separating, and controlling the release of cancer cells from whole blood and normal cells. The GOIN comprises an aptamer-decorated magnetic fluorescent covalent organic framework (COF), which exhibits a strong affinity for nucleolin-overexpressed cancer cells through a multivalent binding effect. The captured cancer cells can be directly imaged using the intrinsic stable fluorescence of the COF layer in the GOIN. Employing magnet and NIR laser assistance enables easy separation and mild photothermal release of CTCs from the normal cells and the nanomachine without compromising cell viability. Moreover, the GOIN demonstrates a reusing capability, as the NIR-triggered CTC release is mild and nondestructive, allowing the GOIN to be reused at least three times.

Revolutionizing the structural design and determination of covalent-organic frameworks: principles, methods, and techniques

Covalent organic frameworks (COFs) represent an important class of crystalline porous materials with designable structures and functions. The interconnected organic monomers, featuring pre-designed symmetries and connectivities, dictate the structures of COFs, endowing them with high thermal and chemical stability, large surface area, and tunable micropores. Furthermore, by utilizing pre-functionalization or post-synthetic functionalization strategies, COFs can acquire multifunctionalities, leading to their versatile applications in gas separation/storage, catalysis, and optoelectronic devices. Our review provides a comprehensive account of the latest advancements in the principles, methods, and techniques for structural design and determination of COFs. These cutting-edge approaches enable the rational design and precise elucidation of COF structures, addressing fundamental physicochemical challenges associated with host-guest interactions, topological transformations, network interpenetration, and defect-mediated catalysis.

Boosting Microwave Thermo-Dynamic Cancer Therapy of TiMOF via COF-Coating

Microwave (MW) dynamic therapy (MDT) can efficiently eliminate tumor residue resulting from MW thermal therapy. However, MDT is currently in its infancy, and luck of effective MDT sensiters severely limits its clinical therapeutic effect. Herein, based on TiMOF (TM), a high-efficiency MW sensitizer is designed for MW thermo-dynamic therapy. TM can generate heat and cytotoxic reacyive oxygen species (ROS) under MW irradiation and has the potential to be used as an MW sensitizer, while the suboptimal MW dynamic sensitization effect of TM limits its application. Inorder to improve the MW dynamic sensitization performance, a covalent organic framework (COF) with good stability and a large conjugate system is used to cover TM, which is conductive to electron and energy transfer, thus increasing the ROS generation rate and prolonging the ROS lifetime. In addition, loading Ni NPs endow nanomaterials with magnetic resonance imaging capabilities. Therefore, this work develops an MW sensitizer based on TM for the first time, and the mechanism of COF coating to enhance the MW dynamic sensitization of TM is preliminarily explored, which provides a new idea for the further development of MW sensitizer with great potential.

Covalent Organic Framework-Based Nanomotor for Multimodal Cancer Photo-Theranostics

Developing efficient integrated diagnosis and treatment agents based on fuel-free self-movement nanomotors remains challenging in antitumor therapy. In this study, a covalent organic framework (COF)-based biomimetic nanomotor composed of polypyrrole (PPy) core, porphyrin-COF shell, and HCT116 cancer cell membrane coating is reported. Under near-infrared (NIR) light irradiation, the obtained mPPy@COF-Por can overcome Brownian motion and achieves directional motion through self-thermophoretic force generated from the PPy core. The HCT116 cancer cell membrane coating enables the nanomotor to selectively recognize the source cell lines and reduces the bio-adhesion of mPPy@COF-Por in a biological medium, endowing with this NIR light-powered nanomotor good mobility. More importantly, such multifunctional integration allows the COF-based nanomotor to be a powerful nanoagent for cancer treatment, and the high infrared thermal imaging/photoacoustic imaging/fluorescence trimodal imaging-guided combined photothermal/photodynamic therapeutic effect on HCT116 tumor cell is successfully achieved. The results offer considerable promise for the development of COF nanomotors with integrated imaging/therapy modalities in biomedical applications.

Drug delivery using biocompatible covalent organic frameworks (COFs) towards a therapeutic approach

Covalent organic frameworks (COFs) are constructed exclusively with lightweight organic scaffolds, which can have a 2D or 3D architecture. The ease of synthesis, robust skeleton and tunable properties of COFs make them superior candidates among their counterparts for a wide range of uses including biomedical applications. In the biomedical field, drug delivery or photodynamic-photothermal (PDT-PTT) therapy can be individually considered a potential parameter to be investigated. Therefore, this comprehensive review is focused on drug delivery using COFs, highlighting the encapsulation and decapsulation of drugs by COF scaffolds and their delivery in biological media including live cells. Versatile COF scaffolds together with the delivery of several drug molecules are considered. We attempted to incorporate the status of drug encapsulation and decapsulation considering a wide range of recent publications.

Tumor-derived covalent organic framework nanozymes for targeted chemo-photothermal combination therapy

Covalent organic frameworks (COFs) have garnered enormous attention in anti-cancer therapy recently. However, the intrinsic drawbacks such as poor biocompatibility and low target-specificity greatly restrain the full clinical implementation of COF. Herein, we report a biomimetic multifunctional COF nanozyme, which consists of AIEgen-based COF (TPE-s COF) with encapsulated gold nanoparticles (Au NPs). The nanozyme was co-cultured with HepG2 cells until the cell membrane was fused with lipophilic TPE-s COF-Au@Cisplatin. By using the cryo-shocking method, we fabricated an inactivated form of the TPE-s COF-Au@Cisplatin nanozyme endocytosed in the HepG2 cell membrane (M@TPE-s COF-Au@Cisplatin), which lost their proliferative ability and pathogenicity. Upon laser irradiation, the M@TPE-s COF-Au@Cisplatin nanozymes cleaved, thereby releasing the TPE-s COF-Au nanozyme and Cisplatin to exert their photothermal and drug therapeutic effect. This work opens a new avenue to the synthesis of tumor-derived fluorescent TPE-s COF-Au nanozymes for highly efficient, synergetic, and targeted chemo-photothermal combination therapy of liver cancer.

Recent Advances in Electrochemical Biosensors for Food Control

The rapid and sensitive detection of food contaminants is becoming increasingly important for timely prevention and treatment of foodborne disease. In this review, we discuss recent developments of electrochemical biosensors as facile, rapid, sensitive, and user-friendly analytical devices and their applications in food safety analysis, owing to the analytical characteristics of electrochemical detection and to advances in the design and production of bioreceptors (antibodies, DNA, aptamers, peptides, molecular imprinted polymers, enzymes, bacteriophages, etc.). They can offer a low limit of detection required for food contaminants such as allergens, pesticides, antibiotic traces, toxins, bacteria, etc. We provide an overview of a broad range of electrochemical biosensing designs and consider future opportunities for this technology in food control.

Composite materials based on covalent organic frameworks for multiple advanced applications

Covalent organic frameworks (COFs) stand for a class of emerging crystalline porous organic materials, which are ingeniously constructed with organic units through strong covalent bonds. Their excellent design capabilities, and uniform and tunable pore structure make them potential materials for various applications. With the continuous development of synthesis technique and nanoscience, COFs have been successfully combined with a variety of functional materials to form COFs-based composites with superior performance than individual components. This paper offers an overview of the development of different types of COFs-based composites reported so far, with particular focus on the applications of COFs-based composites. Moreover, the challenges and future development prospects of COFs-based composites are presented. We anticipate that the review will provide some inspiration for the further development of COFs-based composites.

Recent progress in covalent organic frameworks for cancer therapy

Covalent organic frameworks (COFs) have gained tremendous interest in cancer therapy owing to their multifunctional properties, such as biocompatibility, tunable cavities, excellent crystallinity, ease of modification/functionalization, and high flexibility. These unique properties offer multiple benefits, such as high loading capacity, prevention from premature leakage, targeted delivery to the tumor microenvironment (TME), and release of therapeutic agents in a controlled manner, which makes them effective and excellent nanoplatforms for cancer therapeutics. In this review, we outline recent advances in using COFs as delivery system for chemotherapeutic agents, photodynamic therapy (PDT), photothermal therapy (PTT), sonodynamic therapy (SDT), cancer diagnostics, and combinatorial therapy for cancer therapeutics. We also summarize current challenges and future directions of this unique research field. Teaser: This review highlights recent advances in covalent organic frameworks as multifaceted nanoplatform with recent case studies for improving therapeutic outcomes for cancer therapeutics.

Pt nanozyme-bridged covalent organic framework-aptamer nanoplatform for tumor targeted self-strengthening photocatalytic therapy

Covalent organic frameworks (COFs) have emerged as a promising platform for nanomedicine, while developing multifunctional COF nanoplatforms remains challenging due to the lack of efficient strategies for COF modification. Herein, we propose a nanozyme bridging (NZB) strategy for COF functionalization. Platinum nanoparticles (Pt NPs) as catalase mimics were in situ grown on the surface of COF NPs without reducing their drug loading capacity (CP), and thiol-terminated aptamer was further densely decorated onto CP NPs via a stable Pt-S bond (CPA). Pt nanozyme engineering and aptamer functionalization rendered the nanoplatform with excellent photothermal conversion, tumor targeting, and catalase-like catalytic performances. Using clinical-approved photosensitizer indocyanine green (ICG) as a model drug, we fabricated a nanosystem (ICPA) for tumor-targeted self-strengthening therapy. ICPA can effectively accumulate into tumor tissue and relieve the hypoxia microenvironment by decomposing the overexpressed H₂O₂ and generating O₂. Under monowavelength NIR light irradiation, the catalase-like catalytic and singlet oxygen generation activities of ICPA can be significantly strengthened, leading to admirable photocatalytic treatment effects against malignant cells as well as tumor-bearing mice in a self-strengthening manner.

Construction of Covalent Organic Frameworks via a Visible-Light-Activated Photocatalytic Multicomponent Reaction

Multicomponent reactions (MCRs), as a powerful one-pot combinatorial synthesis tool, have been recently applied to the synthesis of covalent organic frameworks (COFs). Compared with the thermally driven MCRs, the photocatalytic MCR-based COF synthesis has not yet been investigated. Herein, we first report the construction of COFs by a photocatalytic multicomponent reaction. Upon visible-light irradiation, a series of COFs with excellent crystallinity, stability, and permanent porosity are successfully synthesized via photoredox-catalyzed multicomponent Petasis reaction under ambient conditions. Additionally, the obtained Cy-N₃-COF exhibits excellent photoactivity and recyclability for the visible-light-driven oxidative hydroxylation of arylboronic acids. The concept of photocatalytic multicomponent polymerization not only enriches the methodology for COF synthesis but also opens a new avenue for the construction of COFs that might not be possible with the existing synthetic methods based on thermally driven MCRs.

Palladium nanoparticles-confined pore-engineered urethane-linked thiol-functionalized covalent organic frameworks: a high-performance catalyst for the Suzuki Miyaura cross-coupling reaction

Covalent organic frameworks (COFs) are potential templates for the synthesis of nanomaterials owing to the versatility of their structure. Most of the reported COFs comprise imine linkages. Herein, we report for the first time the synthesis of a urethane-linked COF (UCOF) using monoformylphloroglucinol and 1,4-phenylene diisocyanate as monomers. Furthermore, the UCOF was functionalized with cysteamine to introduce free dangling thiol groups into the cavity. The latter played a critical role in fixing the active metal efficiently and facilitating the confined growth of small metal nanoparticles (∼4-6 nm) with a high surface area leading to a pore-engineered heterogeneous Pd catalyst (PdNPs@UCOF-SH). The COF and Pd catalyst were characterized using various analytical techniques such as CP-MAS NMR, FTIR, PXRD, BET, FEG-SEM, HRTEM, XPS, TGA, and ICP-AES. The as-prepared UCOF-SH-supported Pd nanoparticles showed excellent catalytic activity in the Suzuki Miyaura cross-coupling reaction under mild conditions with low catalyst loading and eco-friendly solvents. The scope was extended to various aryl boronic acids and aryl halides (I, Br, and Cl). The halo-substituted and non-halo biaryl derivatives were obtained in good to excellent yields, within a shorter reaction time, avoiding the homocoupling of aryl boronic acid. The pore-engineered COF-derived catalyst is selective and easily recycled up to 10 runs without significant loss of catalytic activity. This reveals the robust nature of the PdNPs@UCOF-SH catalyst and the sustainability of the process which opens a new frontier for several catalytic applications.

A biodegradable covalent organic framework for synergistic tumor therapy

Stimulus-responsive biodegradable nanocarriers with tumor-selective targeted drug delivery are critical for cancer therapy. Herein, we report for the first time a redox-responsive disulfide-linked porphyrin covalent organic framework (COF) that can be nanocrystallized by glutathione (GSH)-triggered biodegradation. After loading 5-fluorouracil (5-Fu), the generated nanoscale COF-based multifunctional nanoagent can be further effectively dissociated by endogenous GSH in tumor cells, releasing 5-Fu efficiently to achieve selective chemotherapy on tumor cells. Together with the GSH depletion-enhanced photodynamic therapy (PDT), an ideal synergistic tumor therapy for MCF-7 breast cancer via ferroptosis is achieved. In this research, the therapeutic efficacy was significantly improved in terms of enhanced combined anti-tumor efficiency and reduced side effects by responding to significant abnormalities such as high concentrations of GSH in the tumor microenvironment (TME).

Emerging application of nanotechnology for mankind

Nanotechnology has proven to be the greatest multidisciplinary field in the current years with potential applications in agriculture, pollution remediation, environmental sustainability, as well as most recently in pharmaceutical industries. As a result of its physical, chemical, and biological productivity, resistance, and matricular organization at a larger scale, the potential of nanocomposites revealed different sorts of assembling structures via testing. Biosensors are known some specifically promising inventions whereas carbon nanotube, magnetic nanoparticles (NPs), quantum dots, and gold NPs showed capability to repair damaged cells, molecular docking, drug-delivery, and nano-remediation of toxic elements. PEGylated(Poly ethyl glycol amyl gated) redox-responsive nanoscale COFs drug delivery from AgNPs and AuNPs are known to be sun blockers in sunscreen lotions. The emerging trends and yet more to be discovered to bridge the gaps forming in the field of nanotechnology, especially insights into environmental concerns and health issues most importantly the food web which is connected with the well beings of mankind to perform its tasks giving necessary results. The current review detailed emerging role of nanomaterials in human life.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42247-023-00461-8.

Construction of Covalent Organic Frameworks via Multicomponent Reactions

Multicomponent reactions (MCRs) combine at least three reactants to afford the desired product in a highly atom-economic way and are therefore viewed as efficient one-pot combinatorial synthesis tools allowing one to significantly boost molecular complexity and diversity. Nowadays, MCRs are no longer confined to organic synthesis and have found applications in materials chemistry. In particular, MCRs can be used to prepare covalent organic frameworks (COFs), which are crystalline porous materials assembled from organic monomers and exhibit a broad range of properties and applications. This synthetic approach retains the advantages of small-molecule MCRs, not only strengthening the skeletal robustness of COFs, but also providing additional driving forces for their crystallization, and has been used to prepare a series of robust COFs with diverse applications. The present perspective article provides the general background for MCRs, discusses the types of MCRs employed for COF synthesis to date, and addresses the related critical challenges and future perspectives to inspire the MCR-based design of new robust COFs and promote further progress in this emerging field.

Amino-Functionalized Ionic-Liquid-Grafted Covalent Organic Frameworks for High-Efficiency CO2 Capture and Conversion

Rationally integrating desired functional components into a composite material can endow the tailored function to achieve the corresponding purpose. This is the first case where a series of [AeImBr]_X%-TAPT-COFs (X = 0, 17, 33, 50, 67, 83, 100) were fabricated by chemically integrating the amino-functionalized imidazole ionic liquid (NH₂-IL) onto channel walls of mesoporous covalent organic framework materials ([HO]_X%-TAPT-COFs). By virtue of the polar groups (amino groups) and abundant imidazole cations of NH₂-IL and its microporous nature, the obtained [AeImBr]_X%-TAPT-COFs exhibit higher CO₂ capture activity than [HO]_X%-TAPT-COFs. Correspondingly, the CO₂ equilibrium capture capacity increases from 62.6 to 117.4 mg/g, which is crucial to the storage of enough CO₂ around the catalytic active sites. Additionally, the synergistic effect of -NH₂ and Br^- in NH₂-IL can also improve the cycloaddition reaction rate. The characteristics of [AeImBr]_X%-TAPT-COFs contribute to the efficient generation of cyclic carbonate through heterogeneously catalyzing CO₂-epoxide cycloaddition without any solvents and cocatalysts. Specifically, [AeImBr]_83%-TAPT-COF has a CO₂ equilibrium capture capacity of 117.4 mg/g and cyclochloroallyl carbonate yield of 99.1%. As a result of the use of the chemical grafting method, [AeImBr]_X%-TAPT-COFs possess excellent stability and cycle life. The equilibrium capture capacity and cyclochloroallyl carbonate yield reach 112.7 mg CO₂/g adsorbent and 95.0% at the eighth cycle.

Functionalization of Covalent Organic Frameworks with Peptides by Polymer-Assisted Surface Modification and the Application for Protein Detection

Although covalent organic frameworks (COFs) have received extensive attention for biomedical research due to their unique properties, their application is still hindered by the challenges of incorporating COFs with functional biomolecules. Since peptides have shown advantages in biomedical applications, herein, we propose the functionalization of COFs with peptides by a polymer-assisted surface modification strategy. Furthermore, a method based on the peptide-functionalized COFs for protein detection has also been developed to demonstrate their application potential. With the help of the polymers, peptides and horseradish peroxidase are attached onto COFs with a high surface density, and the developed method has achieved simple and sensitive detection of the secreted protein acidic and rich in cysteine. We speculate that the facile method proposed in this work to prepare peptide-functionalized COFs can not only benefit protein detection but also promote more biomedical applications of COFs.

Natural Sunlight Photocatalytic Synthesis of Benzoxazole-Bridged Covalent Organic Framework for Photocatalysis

Although natural sunlight-mediated photocatalysis is a clean, efficient, and green approach to access organic products, its application in the synthesis of covalent organic frameworks (COFs), however, is still unprecedented. Herein, we first report the sunlight photocatalytic synthesis of COF under ambient conditions. Furthermore, this "window ledge" reaction generated benzoxazole-linked COF is stable and can be applied as a reusable photocatalyst to highly promote visible-light-driven aerobic oxidation of sulfides to sulfoxides. These results not only enrich the COF synthetic methodology but also open a new route to access COFs in a green and sustainable way.

Ultrathin Covalent Organic Framework Nanosheets/Ti3C2Tx-Based Photoelectrochemical Biosensor for Efficient Detection of Prostate-Specific Antigen

Designable and ultrathin covalent organic framework nanosheets (CONs) with good photoelectric activity are promising candidates for the construction of photoelectrochemical (PEC) biosensors for the detection of low-abundance biological substrates. However, achieving highly sensitive PEC properties by using emerging covalent organic framework nanosheets (CONs) remains a great challenge due to the polymeric nature and poor photoelectric activity of CONs. Herein, we report for the first time the preparation of novel composites and their PEC sensing properties by electrostatic self-assembly of ultrathin CONs (called TTPA-CONs) with Ti₃C₂T_x. The prepared TTPA-CONs/Ti₃C₂T_x composites can be used as photocathodes for PEC detection of prostate-specific antigen (PSA) with high sensitivity, low detection limit, and good stability. This work not only expands the application of CONs but also opens new avenues for the development of efficient PEC sensing platforms.

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

Covalent organic frameworks (COFs) are a class of organic crystalline porous materials discovered in the early 21st century that have become an attractive class of emerging materials due to their high crystallinity, intrinsic porosity, structural regularity, diverse functionality, design flexibility, and outstanding stability. However, many chemical and physical properties strongly depend on the presence of metal ions in materials for advanced applications, but metal-free COFs do not have these properties and are therefore excluded from such applications. Metalated COFs formed by combining COFs with metal ions, while retaining the advantages of COFs, have additional intriguing properties and applications, and have attracted considerable attention over the past decade. This review presents all aspects of metalated COFs, from synthetic strategies to various applications, in the hope of promoting the continued development of this young field.

Synthesis of covalent organic frameworks via Kabachnik-Fields reaction for water treatment

Providing safe and clean domestic water for people is currently one of the greatest worldwide issues. In this context, heavy metal ions and pathogenic microbes are the two major factors in water pollution. The conventional water treatment methods, however, are generally high-energy and high-resource consumptive. Herein, we report, the first of its kind, the room-temperature synthesis of α-aminophosphonate-linked COFs via three-component one-pot in situ Kabachnik-Fields reaction (KF-3CR). Due to the coexistent bioactive α-aminophosphonate and photosensitive porphyrin, the obtained APCOF-1 exhibits highly efficient solar-powered bactericidal and heavy metal ion removal abilities, which allows it to be a promising COF-based multifunctional material for water treatment in an energy- and resource-saving way. Specifically, by incorporating APCOF-1 (up to 50 wt%) with eco-friendly and low-cost chitosan, an APCOF-1 @chitosan aerogel-based helical setup is fabricated via a facile templated freeze-drying approach and it can be a continuous flow-through water purifier model to achieve scaled-up water treatment through adsorptive removal of heavy metal ions and sunlight-driven sterilization. We believe that this research not only can significantly enrich the synthetic methodology of COFs, but also will hopefully bring COFs one step closer to the practical application.

Bimodal Treatment of Hepatocellular Carcinoma by Targeted Minimally Interventional Photodynamic/Chemotherapy Using Glyco-Covalent-Organic Frameworks-Guided Porphyrin/Sorafenib

Very limited treatment options are available to fight hepatocellular carcinoma (HCC), a serious global health concern with high morbidity and mortality. The integration of multiple therapies into one nanoplatform to exert synergistic therapeutic effects offers advantages over monotherapies. Here, we describe the construction of the nanoplatform Sor@GR-COF-366 for synergistic chemotherapy and photodynamic therapy (PDT) for HCC using a porphyrin-based covalent organic framework (COF-366) coated with N-acetyl-galactosamine (GalNAc) and rhodamine B (RhB), and loaded with the first-line agent, Sorafenib (Sor). The nanoplatform is targeted towards ASGPR-overexpressed HCC cells and liver tissues by GalNAc and observed by real-time imaging of RhB in vitro and in vivo. The nanoplatform Sor@GR-COF-366 exerts an enhanced synergistic tumor suppression effect in a subcutaneous HCC mouse model with a tumor inhibition rate (TGI) of 97% while significantly prolonging survival at very low toxicity. The potent synergistic therapeutic outcome is confirmed in an orthotopic mouse model of HCC with the TGI of 98% with a minimally invasive interventional PDT (IPDT). Sor@GR-COF-366 is a promising candidate to be combined with chemo-IPDT for the treatment of HCC. STATEMENT OF SIGNIFICANCE: This work describes the construction of covalent-organic frameworks (COFs) modified with glyco-moieties to serve as hepato-targeted multitherapy delivery systems. They combine minimally invasive interventional photodynamic therapy (IPDT) triggered synergism with chemotherapy treatment for hepatocellular carcinoma (HCC). With the aid of minimally invasive intervention, PDT can elicit potent anti-cancer activity for deep solid tumors. This platform shows strong therapeutic outcomes in both subcutaneous and orthotopic mouse models, which can significantly prolong survival. This work showed an effective combination of a biomedical nano-formulation with the clinical operational means in cancer treatment, which is greatly promising in clinical translation.

Photosensitizer Encryption with Aggregation Enhanced Singlet Oxygen Production

Chromophores that generate singlet oxygen (¹O₂) in water are essential to developing noninvasive disease treatments using photodynamic therapy (PDT). A facile approach for formation of stable colloidal nanoparticles of ¹O₂ photosensitizers, which exhibit aggregation enhanced ¹O₂ generation in water toward applications as PDT agents, is reported. Chromophore encryption within a fuchsonarene macrocyclic scaffold insulates the photosensitizer from aggregation induced deactivation pathways, enabling a higher chromophore density than typical ¹O₂ generating nanoparticles. Aggregation enhanced ¹O₂ generation in water is observed, and variation in molecular structure allows for regulation of the physical properties of the nanoparticles which ultimately affects the ¹O₂ generation. In vitro activity and the ability of the particles to pass through the cell membrane into the cytoplasm is demonstrated using confocal fluorescence microscopy with HeLa cells. Photosensitizer encryption in rigid macrocycles, such as fuchsonarenes, offers new prospects for the production of biocompatible nanoarchitectures for applications involving ¹O₂ generation.

A conjugated 2D covalent organic framework as a drug delivery vehicle towards triple negative breast cancer malignancy

Cancer, one of the deadliest diseases for both sexes, has always demanded updated treatment strategies with time. Breast cancer is responsible for the highest mortality rate among females worldwide and requires treatment with advanced regimens due to the higher probability of breast cancer cells to develop drug cytotoxicity followed by resistance. Covalent organic framework (COF) materials with ordered nanoscale porosity can serve as drug delivery vehicles due to their biocompatible nature and large internal void spaces. In this research work, we have employed a novel biocompatible COF, TRIPTA, as a drug delivery carrier towards breast cancer cells. It served as a drug delivery vehicle for cisplatin in triple negative breast cancer (TNBC) cells. We have checked the potency of TRIPTA in combating the proliferation of metastatic TNBC cells. Our results revealed that cisplatin loaded over TRIPTA-COF exhibited a greater impact on the CD44⁺/CD24^- cancer stem cell niche of breast cancer. Retarded migration of cancer cells has also been observed with the dual treatment of TRIPTA and cisplatin compared to that of cisplatin alone. Epithelial-mesenchymal transition (EMT) has also been minimized by the combinatorial treatment of cisplatin carried by the carrier material in comparison to cisplatin alone. The epithelial marker E-cadherin is significantly increased in cells treated with cisplatin together with the carrier COF, and the expression of mesenchymal markers such as N-cadherin is lower. The transcriptional factor Snail has been observed under the same treatment. The carrier material is also internalized by the cancer cells in a time-dependent manner, suggesting that the organic carrier can serve as a specific drug delivery vehicle. Our experimental results suggested that TRIPTA-COF can serve as a potent nanocarrier for cisplatin, showing higher detrimental effects on the proliferation and migration of TNBC cells by increasing the cytotoxicity of cisplatin.

Glucose Oxidase Integrated Porphyrinic Covalent Organic Polymers for Combined Photodynamic/Chemodynamic/Starvation Therapy in Cancer Treatment

The anticancer effect of photodynamic therapy (PDT) is usually impeded by the hypoxia microenvironment in solid tumors; thus, it requires integration with other treatment tactics to achieve an optimal anticancer efficacy. Porphyrin-containing nanotherapeutic agents are broadly used for PDT in tumor treatment. However, chemodynamic therapy (CDT) of porphyrin-based namomaterials has been rarely reported. Here, a novel nanoscale porphyrin-containing covalent organic polymer (PCOP) was designed by the cross-linking of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin with 1,1'-ferrocenedicarboxylic acid at room temperature. After glucose oxidase (GOx) was loaded, the obtained nanotherapeutic agent of PCOPs@GOx presented an augmented synergy of PDT, CDT, and energy starvation to suppress tumor growth upon near-infrared light irradiation. In vitro and in vivo outcomes demonstrated that this multifunctional nanoplatform not only realized excellent tumor inhibition but also provided a new tactic for designing chemodynamic/photodynamic/starvation combined therapy in one material.

New potential of boron-based COFs: the biocompatible COF-1 for reactive oxygen generation and antimicrobial applications

Photocatalytic covalent organic frameworks (COFs) are popular in the field of biomedical materials and also have potential as antimicrobial materials. Herein, a boron-based COF was used in antibacterial applications innovatively. The results of this study suggested that COF-1, the earliest boroxine COF, could produce a variety of reactive oxygen species (ROS) under visible light irradiation. In order to explore more applications of COF-1, antibacterial tests were carried out based on the above results. The test results showed that the material displayed an obvious bactericidal effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by releasing ROS under white light. According to the results of plate coating, all bacteria died after co-cultivation with COF-1 under white light for about 120 minutes. In a word, this study could provide a new idea for the application of boron-based COFs as multifunctional photocatalysts in future.

A covalent organic framework with a self-contained light source for photodynamic therapy

External light-independent antitumor PDT is successfully realized with a covalent organic framework (COF)-based host-guest nanosystem. Its highly effective antitumor behavior is fully demonstrated by both H₂O₂-overexpressed 4T1 and H₂O₂-less expressed HCT116 and MCF-7 xenograft models.

A CuS- and BODIPY-loaded nanoscale covalent organic framework for synergetic photodynamic and photothermal therapy

Herein, we report an inorganic photothermal agent, CuS- and an organic photosensitizer, BODIPY-loaded composite nanoscale COF material via a stepwise post-synthetic modification. The obtained CuS@COF-BDP can be a dual-modal therapeutic agent to highly inhibit MCF-7 tumor cell proliferation due to its efficient singlet oxygen generation and photothermal conversion abilities.

Characteristic Synthesis of a Covalent Organic Framework and Its Application in Multifunctional Tumor Therapy

For decades, covalent organic frameworks (COFs) have attracted wide biomedical interest due to their unique properties including ease of synthesis, porosity, and adjustable biocompatibility. Versatile COFs can easily encapsulate various therapeutic drugs due to their extremely high payload and porosity. COFs with abundant functional groups can be surface-modified to achieve active targeting and enhance biocompatibility. In this paper, the latest developments of COFs in the biomedical field are summarized. First, the classification and synthesis of COFs are discussed. Cancer diagnosis and treatment based on COFs are studied, and the advantages and limitations of each method are discussed. Second, the specific preparation methods to obtain specific therapeutic properties are summarized. Finally, based on the combination and modification of COFs with various components, this review system summarizes different combination therapies. In addition, the main challenges faced in COF research and prospects for applying COFs to cancer diagnosis and treatment are evaluated. This review provides enlightening insights into the interdisciplinary research on COFs and applications in biomedicine, which highlight the great expectations for their further clinical transformation.

Emerging porous organic polymers for biomedical applications

This review summarizes and discusses the recent progress in porous organic polymers for diverse biomedical applications such as drug delivery, biomacromolecule immobilization, phototherapy, biosensing, bioimaging, and antibacterial applications.