Ultrathin functionalized covalent organic framework nanosheets for tumor-targeted photodynamic therapy

cRGD-Peptide Modified Covalent Organic Frameworks for Precision Chemotherapy in Triple-Negative Breast Cancer

This study presents the use of nanoscale covalent organic frameworks (nCOFs) conjugated with tumor-targeting peptides for the targeted therapy of triple-negative breast cancer (TNBC). While peptides have previously been used for targeted delivery, their conjugation with COFs represents an innovative approach in this field. In particular, we have developed alkyne-functionalized nCOFs chemically modified with cyclic RGD peptides (Alkyn-nCOF-cRGD). This configuration is designed to specifically target αvβ3 integrins that are overexpressed in TNBC cells. These nCOFs exhibit excellent biocompatibility and are engineered to selectively disintegrate under acidic conditions, allowing for precise and localized drug release in tumor environment. Doxorubicin, a chemotherapeutic agent, has been encapsulated in these nCOFs with high loading efficiency. The therapeutic potential of Alkyn-nCOF-cRGD has been demonstrated in vitro and in vivo models. It shows significantly improved drug uptake and targeted cell death in TNBC, highlighting the efficacy of receptor-mediated endocytosis and pH-controlled drug release. This strategy leverages the unique properties of nCOFs with targeted drug delivery to achieve significant advances in personalized cancer therapy and set a new standard for precision chemotherapeutic delivery.

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.

POSS Engineering of Multifunctional Nanoplatforms for Chemo-Mild Photothermal Synergistic Therapy

Chemo-mild photothermal synergistic therapy can effectively inhibit tumor growth under mild hyperthermia, minimizing damage to nearby healthy tissues and skin while ensuring therapeutic efficacy. In this paper, we develop a multifunctional study based on polyhedral oligomeric sesquisiloxane (POSS) that exhibits a synergistic therapeutic effect through mild photothermal and chemotherapy treatments (POSS-SQ-DOX). The nanoplatform utilizes SQ-N as a photothermal agent (PTA) for mild photothermal, while doxorubicin (DOX) serves as the chemotherapeutic drug for chemotherapy. By incorporating POSS into the nanoplatform, we successfully prevent the aggregation of SQ-N in aqueous solutions, thus maintaining its excellent photothermal properties both in vitro and in vivo. Furthermore, the introduction of polyethylene glycol (PEG) significantly enhances cell permeability, which contributes to the remarkable therapeutic effect of POSS-SQ-DOX NPs. Our studies on the photothermal properties of POSS-SQ-DOX NPs demonstrate their high photothermal conversion efficiency (62.3%) and stability, confirming their suitability for use in mild photothermal therapy. A combination index value (CI = 0.72) verified the presence of a synergistic effect between these two treatments, indicating that POSS-SQ-DOX NPs exhibited significantly higher cell mortality (74.7%) and tumor inhibition rate (72.7%) compared to single chemotherapy and mild photothermal therapy. This observation highlights the synergistic therapeutic potential of POSS-SQ-DOX NPs. Furthermore, in vitro and in vivo toxicity tests suggest that the absence of cytotoxicity and excellent biocompatibility of POSS-SQ-DOX NPs provide a guarantee for clinical applications. Therefore, utilizing near-infrared light-triggering POSS-SQ-DOX NPs can serve as chemo-mild photothermal PTA, while functionalized POSS-SQ-DOX NPs hold great promise as a novel nanoplatform that may drive significant advancements in the field of chemo-mild photothermal therapy.

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.

A fluorescence biosensor based on DNA aptamers-COF for highly selective detection of ATP and thrombin

Due to their distinctive physical, chemical, electrical, and optical properties as well as their prospective uses, 2D covalent organic framework (COF) have attracted much attention. Herein, TaTPA-COF was effectively synthesized from the condensation of TTA and TFPA using a facile solvothermal method and characterized by SEM image, FT-IR spectra, and PXRD pattern. The generated bulk TaTPA-COF materials combined with DNA aptamers are utilized as the acceptor (quencher) for the highly sensitive and selective detection of adenosine 5'-triphosphate (ATP) and thrombin, with a novel fluorescence biosensing platform and a proof-of-concept application.

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.

An iodide-containing covalent organic framework for enhanced radiotherapy

Metal-free radiosensitizers, particularly iodine, have shown promise in enhancing radiotherapy due to their suitable X-ray absorption capacities and negligible biotoxicities. However, conventional iodine compounds have very short circulating half-lives and are not retained in tumors very well, which significantly limits their applications. Covalent organic frameworks (COFs) are highly biocompatible crystalline organic porous materials that are flourishing in nanomedicine but have not been developed for radiosensitization applications. Herein, we report the room-temperature synthesis of an iodide-containing cationic COF by the three-component one-pot reaction. The obtained TDI-COF can be a tumor radiosensitizer for enhanced radiotherapy by radiation-induced DNA double-strand breakage and lipid peroxidation and inhibits colorectal tumor growth by inducing ferroptosis. Our results highlight the excellent potential of metal-free COFs as radiotherapy sensitizers.

Covalent organic framework nanomedicines: Biocompatibility for advanced nanocarriers and cancer theranostics applications

Nanomedicines for drug delivery and imaging-guided cancer therapy is a rapidly growing research area. The unique properties of nanomedicines have a massive potential in solving longstanding challenges of existing cancer drugs, such as poor localization at the tumor site, high drug doses and toxicity, recurrence, and poor immune response. However, inadequate biocompatibility restricts their potential in clinical translation. Therefore, advanced nanomaterials with high biocompatibility and enhanced therapeutic efficiency are highly desired to fast-track the clinical translation of nanomedicines. Intrinsic properties of nanoscale covalent organic frameworks (nCOFs), such as suitable size, modular pore geometry and porosity, and straightforward post-synthetic modification via simple organic transformations, make them incredibly attractive for future nanomedicines. The ability of COFs to disintegrate in a slightly acidic tumor microenvironment also gives them a competitive advantage in targeted delivery. This review summarizes recently published applications of COFs in drug delivery, photo-immuno therapy, sonodynamic therapy, photothermal therapy, chemotherapy, pyroptosis, and combination therapy. Herein we mainly focused on modifications of COFs to enhance their biocompatibility, efficacy and potential clinical translation. This review will provide the fundamental knowledge in designing biocompatible nCOFs-based nanomedicines and will help in the rapid development of cancer drug carriers and theranostics.

Acrylate-functionalized porphyrin-covalent organic framework for bacterial-targeted and reaction-enhanced synergistic phototherapy/chemotherapy toward sterilization and wound healing

Porphyrinic covalent organic frameworks (COFs) have emerged as prospective materials in photodynamic and photothermal sterilization. However, it is still a great challenge to construct an efficient COF-based sterilizing agent with good photothermal and photodynamic properties and bacterial targeting ability. Herein, we report a multifunctional porphyrin-COF for bacterial-targeted and reaction-enhanced synergistic phototherapy/chemotherapy for sterilization and wound healing. The ordered crystal structure of the porphyrin-COF not only effectively avoids the self-aggregation-induced quenching of the porphyrin monomer, but also facilitates the storage and transport of singlet oxygen. The acrylate substituent in the other monomer serves as a bacterial targeting moiety and the in situ reaction site with the sulfhydryl group of the bacterial surface protein via a Michael addition reaction, thus fixing the bacteria on the surface of COF and making them lose the colonization ability. Furthermore, the bonding of COF and bacteria further amplifies the therapeutic efficiency of phototherapy. Therefore, the developed multifunctional sterilization platform not only provides a new strategy for the design of novel bactericidal materials but also broadens the biological applications of COF-based materials.

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.

Modulating the antibacterial activity of gold nanoparticles by balancing their monodispersity and aggregation

Aggregation is a key factor influencing the function of nanoparticles. Thioproline-modified gold nanoparticles show potent antibacterial activity, which is compromised by thioproline-mediated particle aggregation. By tuning the balance between the exposure and shielding of thioproline, a maximal antibacterial property of the gold nanoparticles is achieved.

Immunogenicity-boosted cancer immunotherapy based on nanoscale metal-organic frameworks

Immunotherapy, including checkpoint blockade immunotherapy (CBI), has witnessed remarkable progress in cancer therapy. Nonetheless, significant obstacles to successful immunotherapy remain. Notably, tumour non-responsiveness to immunotherapy due to immunosuppressive tumour microenvironments (TMEs). To revitalize immunosuppressive TMEs various therapeutic strategies have been reported by researchers. Immunostimulatory adjuvant treatments (IAT) are the most widely investigated ones. Due to their biodegradability, compositional tenability, and inherent immune effectiveness, nanoscale metal-organic frameworks (nMOFs) with metal nodes and organic linkers can be used as versatile nanomaterials for IAT. This review summarizes the progress in nMOF-based tumour immunotherapy in promoting immunostimulatory TMEs. And in combination with other cancer immunotherapies to increase tumour immunogenicity and antitumor efficacy. Finally, the challenges of nMOFs in tumour immunotherapy are also discussed.

Endoperoxide-containing covalent organic framework as a singlet oxygen reservoir for cancer therapy

A porphyrin-based COF containing dialkylnaphthalene derivative was constructed to deliver extracellular singlet oxygen (1O2) into cancer cells through the Diels-Alder/retro-Diels-Alder reaction between dialkylnaphthalene and 1O2 to realize a light- and...

Cell membrane-anchoring covalent organic framework nanosheets for single-laser-triggered synergistic tumor therapy

Herein, pHLIP engineered COF NSs were developed for cell membrane-anchoring synergistic tumor therapy under single laser irradiation.

Multicolor Covalent Organic Framework-DNA Nanoprobe for Fluorescence Imaging of Biomarkers with Different Locations in Living Cells

Precisely detecting biomarkers in living systems holds tremendous promise for disease diagnosis and monitoring. Herein, we developed a covalent organic framework (COF)-based tricolor fluorescent nanoprobe for simultaneously imaging biomarkers with different spatial locations in living cells. Briefly, a TAMRA-labeled survivin mRNA antisense nucleotide and a Cy5-labeled transmembrane glycoprotein mucin 1 (MUC1) aptamer were adsorbed on a nanoscale fluorescent COF. To enhance the interactions between COF nanoparticles (NPs) and nucleic acid molecules, a freezing method was employed for improving the nucleic acid loading density and ensuring detection performance. The fluorescence signals of dyes on DNAs were first quenched by the COF NPs. Internalization and distribution of the nanoprobes can be real-time visualized by the autofluorescence of COF NPs. In living cells, recognition between MUC1 with MUC1 aptamers causes fluorescence signal recovery of Cy5, while hybridization between survivin mRNA and its antisense DNA induces the signal recovery of TAMRA. Therefore, this COF-based multicolor nanoprobe could be employed for visualizing MUC1 on the cell membrane and survivin mRNA in the cytoplasm. Cancer cell-specific diagnostic imaging and monitoring of the process of cancer cell exosomes infecting normal cells using the nanoprobe were achieved. This work not only offers a versatile nanoprobe for bioanalysis but also provides new insights for developing novel COF-based nanoprobes.

Covalent Organic Framework-Derived Carbonous Nanoprobes for Cancer Cell Imaging

Covalent organic frameworks (COFs) have emerged as promising materials for biomedical applications, but their functions remain to be explored and the potential toxicity concerns should be resolved. Herein, it is presented that carbonization significantly enhances the fluorescence quenching efficiency and aqueous stability of nanoscale COFs. The probes prepared by physisorbing dye-labeled nucleic acid recognition sequences onto the carbonized COF nanoparticles (termed C-COF) were employed for cell imaging, which could effectively light up biomarkers (survivin and TK1 mRNA) in living cells. The C-COF has enhanced photothermal conversion capacity, indicating that the probes are also promising candidates for photothermal therapy. The potential toxicity concern from the aromatic rigid building units of COFs was detoured by carbonization. Overall, carbonization is a promising strategy for developing biocompatible and multifunctional COF-derived nanoprobes for biomedical applications. This work may inspire more versatile COF-derived nanoprobes for bioanalysis and nanomedicine.

Covalent Organic Framework-Based Spherical Nucleic Acid Probe with a Bonding Defect-Amplified Modification Strategy

Developing spherical nucleic acids with new structures holds great promise for nanomedicine and bioanalytical fields. Covalent organic frameworks (COFs) are emerging promising materials with unique properties for a wide range of applications. However, devising COF-based spherical nucleic acid is challenging because methods for the preparation of functionalized COFs are still limited. We report here a bonding defect-amplified modification (BDAM) strategy for the facile preparation of functionalized COFs. Poly(acrylic acid) was employed as the defect amplifier to modify the surface of COF nanoparticles by the formation of amide bonds with amino residues, which successfully converted and amplified the residues into abundant reactive carboxyl groups. Then, amino terminal-decorated hairpin DNA was densely grafted onto the surface of COF nanoparticles (NPs) to give rise to a spherical nucleic acid probe (SNAP). A series of experiments and characterizations proved the successful preparation of the COF-based SNAP, and its application in specifically lighting up RNA biomarkers in living cells for cancer diagnostic imaging was demonstrated. Therefore, the COF-based SNAP is a promising candidate for biomedical applications and the proposed BDAM represents a useful strategy for the preparation of functionalized COFs for diverse fields.

Nucleic Acid-Gated Covalent Organic Frameworks for Cancer-Specific Imaging and Drug Release

Developing nanoplatforms that simultaneously integrate diagnostic imaging and therapy functions has been a promising but challenging task for cancer theranostics. Herein, we report the rational design of a smart nucleic acid-gated covalent organic framework (COF) nanosystem for cancer-specific imaging and microenvironment-responsive drug release. Cy5 dye-labeled single-stranded DNA (ssDNA) for mRNA recognition was adsorbed on the surface of doxorubicin (Dox)-loaded COF nanoparticles (NPs). Dox loaded in the pores of COF NPs could strengthen the interactions between ssDNA and COF and enhance the fluorescence quenching effect toward Cy5, while the densely coated ssDNA could prevent the leakage of Dox from COF NPs. The obtained nanosystem exhibited low fluorescence signal and Dox release in normal cells; however, the ssDNA could be released by the overexpressed TK1 mRNA in cancer cells to recover the intense fluorescence signal of Cy5, and the loaded Dox could be further released for chemotherapy. Therefore, cancer cell-specific diagnostic imaging and drug release were realized with the rationally developed nanosystem. This work offers a universal nanoplatform for cancer theranostics and a promising strategy for regulating the interaction between COFs and biomolecules.