Persistent luminescent metal-organic frameworks with long-lasting near infrared emission for tumor site activated imaging and drug delivery

Lighting up endogenous H2O2 in the tumor microenvironment using a dual-mode nanoprobe for long afterglow and MR bioimaging

Persistent luminescent nanoparticles (PLNPs) are excellent luminescent materials, and near-infrared PLNPs are efficiently applied for biosensing and bioimaging due to their advantages of no excitation, excellent light stability and long afterglow. However, due to interference from the complex environment within organisms, single-mode imaging methods often face limitations in selectivity, sensitivity, and accuracy. Therefore, it is desirable to construct a dual-mode imaging probe strategy with higher specificity and sensitivity for bioimaging. Magnetic resonance imaging (MRI) has been widely used in the field of bioimaging due to its advantages of high resolution, non-radiation and non-invasiveness. Here, by combining near-infrared PLNPs and manganese dioxide (MnO2) nanosheets, a sensitive and convenient dual-mode "turn on" bioimaging nanoprobe ZGC@MnO2 has been developed for long afterglow imaging and MRI of endogenous hydrogen peroxide (H2O2) in the tumor microenvironment (TME). The monitoring of H2O2 has garnered significant attention due to its crucial role in human pathologies. For the dual-mode "turn on" bioimaging nanoprobe, the near-infrared PLNPs of quasi-spherical ZnGa2O4:Cr (ZGC) nanoparticles were synthesized as luminophores, and MnO2 nanosheets were utilized as a fluorescence quencher, carrier and H2O2 recognizer. H2O2 in the TME could reduce MnO2 nanosheets to Mn2+ for MRI, and ZGC nanoparticles were released for long afterglow imaging. Finally, the ZGC@MnO2 nanoprobe exhibited a rapid response, an excellent signal-to-noise ratio and a limit of detection of 3.67 nM for endogenous H2O2 in the TME. This dual-mode approach enhances the detection sensitivity for endogenous H2O2, thereby facilitating the research of endogenous H2O2-associated diseases and clinical diagnostics.

Integrated design and application of stimuli-responsive metal-organic frameworks in biomedicine: current status and future perspectives

In recent years, metal-organic frameworks (MOFs) have garnered widespread attention due to their distinctive attributes, such as high surface area, tunable properties, biodegradability, extremely low density, high loading capacity, diverse chemical functionalities, thermal stability, well-defined pore sizes, and molecular dimensions. Increasingly, biomedical researchers have turned their focus towards their multifaceted development. Among these, stimuli-responsive MOFs, with their unique advantages, have captured greater interest from researchers. This review will delve into the merits and drawbacks of both endogenous and exogenous stimuli-responsive MOFs, along with their application directions. Furthermore, it will outline the characteristics of different synthesis routes of MOFs, exploring various design schemes and modification strategies and their impacts on the properties of MOF products, as well as how to control them. Additionally, we will survey different types of stimuli-responsive MOFs, discussing the significance of various MOF products reported in biomedical applications. We will categorically summarize different strategies such as anticancer therapy, antibacterial treatment, tissue repair, and biomedical imaging, as well as insights into the development of novel MOFs nanomaterials in the future. Finally, this review will conclude by summarizing the challenges in the development of stimuli-responsive MOFs in the field of biomedicine and providing prospects for future research endeavors.

Recent advances in near-infrared I/II persistent luminescent nanoparticles for biosensing and bioimaging in cancer analysis

Photoluminescent materials (PLNs) are photoluminescent materials that can absorb external excitation light, store it, and slowly release it in the form of light in the dark to achieve long-term luminescence. Developing near-infrared (NIR) PLNs is critical to improving long-afterglow luminescent materials. Because they excite in vitro, NIR-PLNs have the potential to avoid interference from in vivo autofluorescence in biomedical applications. These materials are promising for biosensing and bioimaging applications by exploiting the near-infrared biological window. First, we discuss the biomedical applications of PLNs in the first near-infrared window (NIR-I, 700-900 nm), which have been widely developed and specifically introduce biosensors and imaging reagents. However, the light in this area still suffers from significant light scattering and tissue autofluorescence, which will affect the imaging quality. Over time, fluorescence imaging technology in the second near-infrared window (NIR-II, 1000-1700 nm) has also begun to develop rapidly. NIR-II fluorescence imaging has the advantages of low light scattering loss, high tissue penetration depth, high imaging resolution, and high signal-to-noise ratio, and it shows broad application prospects in biological analysis and medical diagnosis. This critical review collected and sorted articles from the past 5 years and introduced their respective fluorescence imaging technologies and backgrounds based on the definitions of NIR-I and NIR-II. We also analyzed the current advantages and dilemmas that remain to be solved. Herein, we also suggested specific approaches NIR-PLNs can use to improve the quality and be more applicable in cancer research.

Zeolitic imidazole framework-derived rich-Zn-Co3O4/N-doped porous carbon with multiple enzyme-like activities for synergistic cancer therapy

Reactive oxygen species (ROS)-centered chemodynamic therapy (CDT) holds significant potential for tumor-specific treatment. However, insufficient endogenous H2O2 and extra glutathione within tumor microenvironment (TME) severely deteriorate the CDT's effectiveness. Herein, rich-Zn-Co3O4/N-doped porous carbon (Zn-Co3O4/NC) was fabricated by two-step pyrolysis, and applied to build high-efficiency nano-platform for synergistic cancer therapy upon combination with glucose oxidase (GOx), labeled Zn-Co3O4/NC-GOx for clarity. Specifically, the multiple enzyme-like activities of the Zn-Co3O4/NC were scrutinously investigated, including peroxidase-like activity to convert H2O2 to O2∙-, catalase-like activity to decompose H2O2 into O2, and oxidase-like activity to transform O2 to O2∙-, which achieved the CDT through the catalytic cascade reaction. Simultaneously, GOx reacted with intracellular glucose to produce gluconic acid and H2O2, realizing starvation therapy. In the acidic TME, the Zn-Co3O4/NC-GOx rapidly caused intracellular Zn2+ pool overload and disrupted cellular homeostasis for ion-intervention therapy. Additionally, the Zn-Co3O4/NC exhibited glutathione peroxidase-like activity, which consumed glutathione in tumor cells and reduced the ROS consumption for ferroptosis. The tumor treatments offer some constructive insights into the nanozyme-mediated catalytic medicine, coupled by avoiding the TME limitations.

Acid-Responsive Decomposable Nanomedicine Based on Zeolitic Imidazolate Frameworks for Near-Infrared Fluorescence Imaging/Chemotherapy Combined Tumor Theranostics

Zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (NPs) are gaining traction in tumor theranostics for their effectiveness in encapsulating both imaging agents and therapeutic drugs. While typically, similar hydrophilic molecules are encapsulated in either pure aqueous or organic environments, few studies have explored co-encapsulation of chemotherapeutic drugs and imaging agents with varying hydrophilicity and, consequently, constructed multifunctional ZIF-8 composite NPs for acid-responsive, near-infrared fluorescence imaging/chemotherapy combined tumor theranostics. Here, we present a one-pot method for the synthesis of uniform Cy5.5&DOX@ZIF-8 nanoparticles in mixed solvents, efficiently achieving simultaneous encapsulation of hydrophilic doxorubicin (DOX) and hydrophobic Cyanine-5.5 (Cy5.5). Surface decoration with dextran (Dex) enhanced colloidal stability and biocompatibility. The method significantly facilitated co-loading of Cy5.5 dyes and DOX drugs, endowing the composite NPs with notable fluorescent imaging capabilities and pH-responsive chemotherapy capacities. In vivo near-infrared fluorescence (NIRF) imaging in A549 tumor-bearing mice demonstrated significant accumulation of Cy5.5 at tumor sites due to enhanced permeability and retention (EPR) effects, with fluorescence intensities approximately 48-fold higher than free Cy5.5. Enhanced therapeutic efficiency was observed in composite NPs compared to free DOX, validating tumor-targeted capability. These findings suggest ZIF-8-based nanomedicines as promising platforms for multifunctional tumor theranostics.

Maternal exposure to ZIF-8 derails placental function by inducing trophoblast pyroptosis through neutrophils activation in mice

Adverse environmental factors during maternal gestation pose a threat to pregnancy. Environmental factors, particularly nanoparticles, can impact pregnancy by causing damage to the placenta. Compared to early gestation, foetuses in late gestation are more robustly developed and at lower risk of adverse effects from environmental factors. Delivery systems for targeted therapy during pregnancy is predominantly focused on their application in late gestation. Zeolitic imidazolate framework-8 (ZIF-8) holds great potential for targeted drug therapy. To evaluate the value of ZIF-8 in targeted treatment of disorders associated with late gestation, it is crucial to investigate the biological effects of ZIF-8 exposure during late gestation. Here, a mouse model exposed to ZIF-8 particles at different doses (5, 10, and 15 mg/kg) during late gestation was constructed. We found that ZIF-8 particles were deposited in the uterus of pregnant mice. ZIF-8 could trigger placental neutrophil aggregation and induce inflammation, which led to trophoblast pyroptosis and impair placental function, adversely affecting the foetus. Neutrophil depletion alleviated placental and foetal damage induced by ZIF-8. This study provides a novel mechanistic view of the reproductive toxicity induced by ZIF-8 and may offer clues to reduce the latent harm of adverse environmental factors to pregnancy.

Nanocluster/metal-organic framework nanosheet-based confined ECL enhancement biosensor for the extracellular vesicle detection

Gastric cancer (GC) was one of the most common cancers with high mortality. The detection of GC peritoneal metastasis had important significance. In this work, we have developed the novel electrochemiluminescence (ECL) biosensor to detect microRNA in GC extracellular vesicle (EV). Firstly, in situ growth of Cu nanocluster (Cu NC) on the metal-organic frameworks (MOFs) nanosheet was achieved successfully. Due to the confinement effect, Cu NCs in the porous structure of Zn MOF possessed the high quantum yield and good stability. Meanwhile, Zn MOF provided good electrochemical activity for the ECL reaction. Furthermore, the nanosized MOFs did not only act as sensing platform to load Cu NCs and link biomolecules, but also reduce steric hindrance effect for biomolecular recognition. Additionally, Au NPs/MXene and phospholipid layer were prepared and modified on the electrode, which can regulate electron transfer and improve the target recognition efficiency. The Cu NCs/Zn MOF nanosheet-based ECL sensor was employed to detect miRNA-421 from 1 fM to 1 nM with a detection limit of 0.5 fM. Finally, extracellular vesicles form clinic GC patient ascites were extracted and analyzed. The results showed that the constructed biosensor can be used for the GC peritoneal metastasis diagnosis.

Tunable Zeolitic Imidazolate Framework-8 Nanoparticles for Biomedical Applications

Zeolite imidazole framework-8 (ZIF-8) is the most prestigious one among zeolitic imidazolate framework (ZIF) with tunable dimensions and unique morphological features. Utilizing its synthetic adjustability and structural regularity, ZIF-8 exhibits enhanced flexibility, allowing for a wide range of functionalities, such as loading of nanoparticle components while preserving biomolecules activity. Extensive efforts are made from investigating synthesis techniques to develop novel applications over decades. In this review, the development and recent progress of various synthesis approaches are briefly summarized. In addition, its interesting properties such as adjustable porosity, excellent thermal, and chemical stabilities are introduced. Further, five representative biomedical applications are highlighted based on above physicochemical properties. Finally, the remaining challenges and offered insights into the future outlook are also discussed. This review aims to understand the co-relationships between structures and biomedical functionalities, offering the opportunity to construct attractive materials with promising characteristics.

Recent advances in metal-organic frameworks for stimuli-responsive drug delivery

After entering the human body, drugs for treating diseases, which are prone to delivery and release in an uncontrolled manner, are affected by various factors. Based on this, many researchers utilize various microenvironmental changes encountered during drug delivery to trigger drug release and have proposed stimuli-responsive drug delivery systems. In recent years, metal-organic frameworks (MOFs) have become promising stimuli-responsive agents to release the loaded therapeutic agents at the target site to achieve more precise drug delivery due to their high drug loading, excellent biocompatibility, and high stimuli-responsiveness. The MOF-based stimuli-responsive systems can respond to various stimuli under pathological conditions at the site of the lesion, releasing the loaded therapeutic agent in a controlled manner, and improving the accuracy and safety of drug delivery. Due to the changes in different physical and chemical factors in the pathological process of diseases, the construction of stimuli-responsive systems based on MOFs has become a new direction in drug delivery and controlled release. Based on the background of the rapidly increasing attention to MOFs applied in drug delivery, we aim to review various MOF-based stimuli-responsive drug delivery systems and their response mechanisms to various stimuli. In addition, the current challenges and future perspectives of MOF-based stimuli-responsive drug delivery systems are also discussed in this review.

A critical review on metal-organic frameworks (MOFs) based nanomaterials for biomedical applications: Designing, recent trends, challenges, and prospects

Nanomaterials (NMs) have garnered significant attention in recent decades due to their versatile applications in a wide range of fields. Thanks to their tiny size, enhanced surface modifications, impressive volume-to-surface area ratio, magnetic properties, and customized optical dispersion. NMs experienced an incredible upsurge in biomedical applications including diagnostics, therapeutics, and drug delivery. This minireview will focus on notable examples of NMs that tackle important issues, demonstrating various aspects such as their design, synthesis, morphology, classification, and use in cutting-edge applications. Furthermore, we have classified and outlined the distinctive characteristics of the advanced NMs as nanoscale particles and hybrid NMs. Meanwhile, we emphasize the incredible potential of metal-organic frameworks (MOFs), a highly versatile group of NMs. These MOFs have gained recognition as promising candidates for a wide range of bio-applications, including bioimaging, biosensing, antiviral therapy, anticancer therapy, nanomedicines, theranostics, immunotherapy, photodynamic therapy, photothermal therapy, gene therapy, and drug delivery. Although advanced NMs have shown great potential in the biomedical field, their use in clinical applications is still limited by issues such as stability, cytotoxicity, biocompatibility, and health concerns. This review article provides a thorough analysis offering valuable insights for researchers investigating to explore new design, development, and expansion opportunities. Remarkably, we ponder the prospects of NMs and nanocomposites in conjunction with current technology.

Topical drug delivery strategies for enhancing drug effectiveness by skin barriers, drug delivery systems and individualized dosing

Topical drug delivery is widely used in various diseases because of the advantages of not passing through the gastrointestinal tract, avoiding gastrointestinal irritation and hepatic first-pass effect, and reaching the lesion directly to reduce unnecessary adverse reactions. The skin helps the organism to defend itself against a huge majority of external aggressions and is one of the most important lines of defense of the body. However, the skin's strong barrier ability is also a huge obstacle to the effectiveness of topical medications. Allowing the bioactive, composition in a drug to pass through the stratum corneum barrier as needed to reach the target site is the most essential need for the bioactive, composition to exert its therapeutic effect. The state of the skin barrier, the choice of delivery system for the bioactive, composition, and individualized disease detection and dosing planning influence the effectiveness of topical medications. Nowadays, enhancing transdermal absorption of topically applied drugs is the hottest research area. However, enhancing transdermal absorption of drugs is not the first choice to improve the effectiveness of all drugs. Excessive transdermal absorption enhances topical drug accumulation at non-target sites and the occurrence of adverse reactions. This paper introduces topical drug delivery strategies to improve drug effectiveness from three perspectives: skin barrier, drug delivery system and individualized drug delivery, describes the current status and shortcomings of topical drug research, and provides new directions and ideas for topical drug research.

Luminescence-Based Infrared Thermal Sensors: Comprehensive Insights

Recent chronological breakthroughs in materials innovation, their fabrication, and structural designs for disparate applications have paved transformational ways to subversively digitalize infrared (IR) thermal imaging sensors from traditional to smart. The noninvasive IR thermal imaging sensors are at the cutting edge of developments, exploiting the abilities of nanomaterials to acquire arbitrary, targeted, and tunable responses suitable for integration with host materials and devices, intimately disintegrate variegated signals from the target onto depiction without any discomfort, eliminating motional artifacts and collects precise physiological and physiochemical information in natural contexts. Highlighting several typical examples from recent literature, this review article summarizes an accessible, critical, and authoritative summary of an emerging class of advancement in the modalities of nano and micro-scale materials and devices, their fabrication designs and applications in infrared thermal sensors. Introduction is begun covering the importance of IR sensors, followed by a survey on sensing capabilities of various nano and micro structural materials, their design architects, and then culminating an overview of their diverse application swaths. The review concludes with a stimulating frontier debate on the opportunities, difficulties, and future approaches in the vibrant sector of infrared thermal imaging sensors.

Carbopol dispersed PAA-modified UIO-66 with high colloidal stability as a combination nano-adjuvant boosts immune response and protection against pseudorabies virus in mice and pigs

Although inactivated vaccines have higher safety than live-attenuated vaccines in the control of pseudorabies virus (PRV), their protection efficacy is limited due to insufficient immunogenicity when used alone. High-performance adjuvants that can potentiate immune responses are highly desirable to improve the protection efficacy of inactivated vaccines. In this work, we have developed U@PAA-Car, a Carbopol dispersed zirconium-based metal-organic framework UIO-66 modified by polyacrylic acid (PAA), as a promising adjuvant for inactivated PRV vaccines. The U@PAA-Car has good biocompatibility, high colloidal stability, and antigen (vaccine) loading capacity. It significantly potentiates humoral and cellular immune responses over either U@PAA, Carbopol, or commercial adjuvants such as Alum and biphasic 201 by inducing a higher specific antibody titer, IgG2a/IgG1 ratio, cell cytokine secretion, and splenocyte proliferation. A protection rate of over 90% was observed in challenge tests in the model animal mice and the host animal pigs, which is much higher than that observed with commercial adjuvants. The high performance of the U@PAA-Car is attributed to antigen sustainable release at the injection site and highly efficient antigen internalization and presentation. In conclusion, this work not only demonstrates a great potential of the developed U@PAA-Car nano-adjuvant for the inactivated PRV vaccine but also gives a preliminary explanation of its action mechanism. STATEMENT OF SIGNIFICANCE: We have developed a Carbopol dispersed PAA-modified zirconium-based metal-organic framework UIO-66 (U@PAA-Car) as a promising combination nano-adjuvant for the inactivated PRV vaccine. The U@PAA-Car induced higher specific antibody titers and IgG2a/IgG1 ratio, increased cell cytokines secretion, and better splenocyte proliferation than U@PAA, Carbopol, and the commercial adjuvants Alum and biphasic 201, indicating that it induces a significant potentiation of humoral and cellular immune response. In addition, much higher protection rates were achieved with the U@PAA-Car-adjuvanted PRV vaccine in mice and pigs challenge than those observed from the commercial adjuvant groups. This work not only demonstrates the great potential of the U@PAA-Car nano-adjuvant in an inactivated PRV vaccine but also gives a preliminary explanation of its action mechanism.

Pre-activated nanoparticles with persistent luminescence for deep tumor photodynamic therapy in gallbladder cancer

Phototherapy of deep tumors still suffers from many obstacles, such as limited near-infrared (NIR) tissue penetration depth and low accumulation efficiency within the target sites. Herein, stimuli-sensitive tumor-targeted photodynamic nanoparticles (STPNs) with persistent luminescence for the treatment of deep tumors are reported. Purpurin 18 (Pu18), a porphyrin derivative, is utilized as a photosensitizer to produce persistent luminescence in STPNs, while lanthanide-doped upconversion nanoparticles (UCNPs) exhibit bioimaging properties and possess high photostability that can enhance photosensitizer efficacy. STPNs are initially stimulated by NIR irradiation before intravenous administration and accumulate at the tumor site to enter the cells through the HER2 receptor. Due to Pu18 afterglow luminescence properties, STPNs can continuously generate ROS to inhibit NFκB nuclear translocation, leading to tumor cell apoptosis. Moreover, STPNs can be used for diagnostic purposes through MRI and intraoperative NIR navigation. STPNs exceptional antitumor properties combined the advantages of UCNPs and persistent luminescence, representing a promising phototherapeutic strategy for deep tumors.

Mesoporous polyacrylic acid/calcium phosphate coated persistent luminescence nanoparticles for improved afterglow bioimaging and chemotherapy of bacterial infection

Coating mesoporous drug carriers on the surface of persistent luminescence nanoparticles (PLNPs) not only allows continuous luminous imaging without spontaneous fluorescence interference, but also provides drug release guidance. However, in most cases, the encapsulation of the drug-loaded shells significantly reduces the luminescence of PLNPs, which is unfavorable for bioimaging. In addition, conventional drug-loaded shells alone, such as silica shells, have difficulty in achieving responsive fast drug release. Herein, we report the fabrication of mesoporous polyacrylic acid (PAA)/calcium phosphate (CaP) shell-coated PLNPs (PLNPs@PAA/CaP) for improved afterglow bioimaging and drug delivery. The encapsulation of the PAA/CaP shell effectively prolonged the decay time and enhanced the sustained luminescence of PLNPs by about three times due to the passivation of the surface defects of PLNPs by the shell, and the energy transfer between the shell and PLNPs. Meanwhile, the mesoporous structure and negative charge of the PAA/CaP shells enabled the prepared PLNPs@PAA/CaP to carry the positively charged drug doxycycline hydrochloride efficiently. Under the acidic conditions of bacterial infection, the degradation of PAA/CaP shells and the ionization of PAA enabled fast drug release for effective killing of bacteria at the infection site. The excellent persistent luminescence properties, outstanding biocompatibility, and rapid responsive release feature make the prepared PLNPs@PAA/CaP a promising nanoplatform for diagnostic and therapeutic applications.

Synthesis, Structure and Near Infrared Fluorescence Property of a New Nd-MOF Based on a Triangular Benzylamine Ligand

A new 3D metal-organic framework (Nd-MOF) {[Nd₂L₂]·2NH₂(CH₃)₂·3H₂O} was successfully established via a solvothermal method with Nd³⁺ ion and 5-(bis(4-carboxybenzyl) amino)-isophthalicacid (H₄L), and has also been characterized by X-ray diffraction, powder X-ray diffraction (PXRD), IR and photoluminescence(PL)spectrum. The neodymium ions are free of coordinated solvents, and the Nd-MOF exhibits strong near-infrared (NIR) fluorescence. Besides, Its NIR fluorescence property shows low temperature resistance, which is favorable for being used in the low temperature environment. Besides, the fluorescence lifetime of Nd-MOF is 6.03 μs, and the quantum yield is 1.2%. The small quantum yield may owe to large energy gap between the T1 of the ligand H₄L and the resonance energy level ⁴F_3/2 of the Nd³⁺ ion, or due to large crystal size of the Nd-MOF.

Persistent luminescent metal-organic framework nanocomposite enables autofluorescence-free dual modal imaging-guided drug delivery

Molecular imaging-guided therapy was essential for realizing precise cancer intervention, while designing an imaging platform to achieve autofluorescence-free imaging for dual modal imaging-guided drug delivery remains a challenge. Near-infrared persistent luminescence nanoparticles (NIR PLNPs) were promising for tumor imaging due to no background interference from the tissue. Herein, a persistent luminescent metal-organic framework (PLNPs@MIL-100(Fe)) is prepared via a layer-by-layer method for dual-modal imaging-guided drug delivery. The PLNPs@MIL-100(Fe) exhibit NIR persistent luminescence emitting and T₂-weighted signal, achieving precise in vivo dual-modal imaging of tumor-bearing mice by providing high spatial resolution MR imaging and autofluorescence-free NIR imaging. The porous MIL-100(Fe) shell provides PLNPs@MIL-100(Fe) with up to 87.1% drug loading capacity and acid-triggered drug release for drug delivery. We envision that the proposed PLNPs@MIL-100(Fe) platform would provide an effective approach for precise tumor imaging and versatile drug delivery.

Perspective and Prospects on persistent luminescent nanoparticles for biological imaging and tumor therapy

Persistent luminescent nanoparticles (PLNPs) are photoluminescent materials that can still emit luminescence after the cessation of the excitation light source. In recent years, due to their unique optical properties, the PLNPs have attracted extensive attention in the biomedical field. Since the PLNPs effectively eliminate autofluorescence interference from biological tissues, many researchers have contributed a lot of work in the fields of biological imaging and tumor therapy. This article mainly introduces the synthesis methods of the PLNPs and their progress in the application of biological imaging and tumor therapy, as well as the challenges and development prospects.

Application of photo-responsive metal-organic framework in cancer therapy and bioimaging

Metal-organic frameworks (MOFs) are a class of hybrid porous crystalline materials that are assembled with metal ions/clusters and organic linkers. The fungibility of organic ligands and metal centers endow MOFs that are easy to design and synthesize. Based on their unique structure, multifarious MOFs with diverse functionalities have recently been widely applied in various research areas. Particularly striking is the application of photo-responsive MOFs in biological sensing and imaging. Notably, the photoelectronic properties make photo-responsive MOFs an ideal platform for cancer phototherapy. Moreover, ultrahigh porosities and tunable pore sizes allow MOFs to load anticancer drugs, further enhancing the antitumor efficiency. In this review, the categories and developing strategies of MOFs are briefly introduced. The application fields of MOFs in bioimaging, such as up-conversion fluorescence imaging, single/two-photon fluorescence bioimaging, magnetic resonance imaging, etc., are summarized. The working mechanism of MOFs in photo-responsive, photothermal therapy (PTT), and photodynamic therapy (PDT) are expounded. Examples of using MOFs for cancer treatment, including PTT, PDT, chemotherapy, and radiotherapy, are also demonstrated. Lastly, current limitations, challenges, and future perspectives for bioimaging and cancer treatment of MOFs are discussed. We believe that the versatile MOF will bring the dawn to the next generation of cancer treatment.

Application of MOF-based nanotherapeutics in light-mediated cancer diagnosis and therapy

Light-mediated nanotherapeutics have recently emerged as promising strategies to precisely control the activation of therapeutic reagents and imaging probe both in vitro and in vivo, largely ascribed to their unique properties, including minimally invasive capabilities and high spatiotemporal resolution. Nanoscale metal-organic frameworks (NMOFs), a new family of hybrid materials consisting of metal attachment sites and bridging ligands, have been explored as a new platform for enhanced cancer diagnosis and therapy due to their tunable size, modifiable surface, good biocompatibility, high agent loading and, most significantly, their ability to be preferentially deposited in tumors through enhanced permeability and retention (EPR). Especially the light-driven NMOF-based therapeutic platform, which not only allow for increased laser penetration depth and enhanced targeting, but also enable imaging-guided or combined treatments. This review provides up-to-date developments of NMOF-based therapeutic platforms for cancer treatment with emphasis on light-triggered therapeutic strategies and introduces their advances in cancer diagnosis and therapy in recent years.

HKUST-1 nano metal-organic frameworks combined with ZnGa2O4:Cr3+ near-infrared persistent luminescence nanoparticles for in vivo imaging and tumor chemodynamic and photothermal synergic therapy

The multifunctional theranostic nanoplatform based on the combination of persistent luminescent nanoparticles (PLNPs) and metal-organic frameworks (MOFs) has both in vivo imaging and tumor therapeutic drug-loading functions, providing a new strategy for accurate and effective tumor diagnosis and treatment. Herein, the near-infrared (NIR) PLNP SiO₂@Zn_1.05Ga_1.9O₄:Cr was combined with HKUST-1 MOFs to form a core-shell structure theranostic nanoplatform which possessed the triple function of autofluorescence-free NIR PersL bioimaging, tumor chemodynamic therapy (CDT), and tumor photothermal therapy (PTT). Also, the photothermal conversion efficiency reached 58.7%, which is superior to the reported nano metal-organic framework (NMOF) photothermal reagents. We demonstrated that the nanoplatform could enter the tumors of mice within 0.5 h and could be target-activated by H₂O₂ and H₂S in the tumor cells, resulting in effective PTT and CDT synergistic treatment. Tumor-bearing mice experiments showed that the tumor could be completely cured without harming normal tissue. This theranostic nanoplatform may provide a promising strategy showing imaging, PTT, and CDT synergistic treatment tri-mode for clinical cancer therapy.

Microvesicle-camouflaged biomimetic nanoparticles encapsulating a metal-organic framework for targeted rheumatoid arthritis therapy

Background

Methotrexate (MTX) has been highlighted for Rheumatoid arthritis (RA) treatment, however, MTX does not accumulate well at inflamed sites, and long-term administration in high doses leads to severe side effects. In this study, a novel anti-RA nanoparticle complex was designed and constructed, which could improve the targeted accumulation in inflamed joints and reduce side effects.

Results

Here, we prepared a pH-sensitive biomimetic drug delivery system based on macrophage-derived microvesicle (MV)-coated zeolitic imidazolate framework-8 nanoparticles that encapsulated the drug methotrexate (hereafter MV/MTX@ZIF-8). The MV/MTX@ZIF-8 nanoparticles were further modified with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[folate (polyethylene glycol)-2000] (hereafter FPD/MV/MTX@ZIF-8) to exploit the high affinity of folate receptor β for folic acid on the surface of activated macrophages in RA. MTX@ZIF-8 nanoparticles showed high DLE (~ 70%) and EE (~ 82%). In vitro study showed that effective drug release in an acidic environment could be achieved. Further, we confirmed the activated macrophage could uptake much more FPD/MV/MTX@ZIF-8 than inactivated cells. In vivo biodistribution experiment displayed FPD/MV/MTX@ZIF-8 nanoparticles showed the longest circulation time and best joint targeting. Furthermore, pharmacodynamic experiments confirmed that FPD/MV/MTX@ZIF-8 showed sufficient therapeutic efficacy and safety to explore clinical applications.

Conclusions

This study provides a novel approach for the development of biocompatible drug-encapsulating nanomaterials based on MV-coated metal-organic frameworks for effective RA treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01447-0.

An Energy-Storing DNA-Based Nanocomplex for Laser-Free Photodynamic Therapy

Photodynamic therapy (PDT) is a therapeutic strategy that is dependent on external light irradiation that faces a major challenge in cancer treatment due to the poor tissue-penetration depths of light irradiation. Herein, a DNA nanocomplex that integrates persistent-luminescence nanoparticles (PLNPs) is developed, which realizes tumor-site glutathione-activated PDT for breast cancer without exogenous laser excitation. The scaffold of the nanocomplex is AS1411-aptamer-encoded ultralong single-stranded DNA chain with two functions: i) providing sufficient intercalation sites for the photosensitizer, and ii) recognizing nucleolin that specifically overexpresses on the surface of cancer cells. The PLNPs in the nanocomplex are energy-charged to act as a self-illuminant and coated with a shell of MnO₂ for blocking energy degradation. In response to the overexpressed glutathione in cancer cells, the MnO₂ shell decomposes to provide Mn²⁺ to catalytically produce O₂ , which is essential to PDT. Meanwhile, PLNPs are released and act as a self-illuminant to activate the photosensitizer to convert O₂ into cytotoxic ¹ O₂ . Significant tumor inhibition effects are demonstrated in breast tumor xenograft models without exogenous laser excitation. It is envisioned that a laser-excitation-free PDT strategy enabled by the PLNP-DNA nanocomplex promotes the development of PDT and provides a new local therapeutic approach.

Increasing the Stability of Metal-Organic Frameworks by Coating with Poly(tetrafluoroethylene)

When compared to industrially stable zeolites, the instability of metal-organic frameworks (MOFs) has been denounced by researchers. Boosting the stability of existing MOFs is highly important for practical applications. In this report, we develop a new strategy to prepare MOFs/poly(tetrafluoroethylene) (PTFE) composites, which can highly improve the chemical, pressure, and photostabilities of zeolitic imidazolate framework (ZIF)-8. Composite materials were prepared by a physical blending of ZIF-8 and PTFE emulsion with different ratios and annealing at 370 °C. Transmission electron microscopy (TEM) studies reveal that the nanoparticles of ZIF-8 are coated by PTFE to form the composite materials. Upon mixing with 20 or 50 wt % PTFE, the ZIF-8/PTFE materials show a superhydrophobic property with water contact angles of around 156°. Pristine ZIF-8 is not stable in water with stirring under acidic, basic, and irradiation conditions, while the ZIF-8/PTFE materials are stable under the same conditions. The ZIF-8/PTFE materials can also maintain their crystalline structure after being compressed with a 10 MPa pressure, while pristine ZIF-8 changes to an amorphous solid after the same pressure treatment. Using water as a solvent, ZIF-8/PTFE can be used as a highly efficient and recyclable catalyst for Knoevenagel reaction at room temperature. The successful preparation of stable ZIF-8/PTFE composite materials provides a useful method to enhance the chemical, pressure, and photostabilities of MOFs.

Biomimetic multifunctional persistent luminescence nanoprobes for long-term near-infrared imaging and therapy of cerebral and cerebellar gliomas

Glioma is the most common malignant primary brain tumor, and the accurate diagnosis of glioma has always been a challenge. Moreover, cerebellar glioma, which is difficult to be detected by magnetic resonance imaging, is not usually diagnosed until after the appearance of clinical symptoms. In this study, TRZD, a near-infrared (NIR) persistent luminescence (PL) nanoparticle with a dual function of imaging and therapy, was synthesized based on ZnGa₂O₄:Cr³⁺,Sn⁴⁺. TRZD showed excellent rechargeable NIR PL for more than 30 hours in vivo with good tissue penetration for long-term autofluorescence-free imaging. The tumor growth of both the subcutaneous and orthotropic glioma models was significantly inhibited by TRZD. This is the first-time approach using NIR PL nanoprobes for both diagnosis and therapy of glioma. This is also the first-time report of nanotechnology-based diagnosis and therapy of cerebellar gliomas. This study offers a highly promising multifunctional nanoparticle for theranostics of a wide range of brain diseases.

Current status and future prospects of nanoscale metal–organic frameworks in bioimaging

The importance of diagnosis and in situ monitoring of lesion regions and transportation of bioactive molecules has a pivotal effect on successful treatment, reducing side effects, and increasing the chances of survival in the case of diseases.

Monodisperse ZIF-8@dextran nanoparticles co-loaded with hydrophilic and hydrophobic functional cargos for combined near-infrared fluorescence imaging and photothermal therapy

Impressive developments have been achieved with the use of zeolitic imidazolate framework-8 (ZIF-8) as nanocarriers for tumor theranostics in recent decades by incorporating imaging agents and therapeutic drugs within ZIF-8. However, the simultaneous immobilization of hydrophilic and hydrophobic functional molecules into ZIF-8 nanoparticles in water or organic solvents still presents a daunting challenge. Herein, we developed a new synthesis/encapsulation two-in-one (denoted as one-pot) approach to synthesize uniform dextran-modified Cy5.5&ICG@ZIF-8-Dex nanoparticles in DMSO/H₂O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) during the same step. It was confirmed that the one-pot approach in this mixed solvents facilitated the loading of ICG and Cy5.5 molecules. Moreover, the encapsulation of Cy5.5 and ICG within ZIF-8 nanoparticles endowed them with fluorescence imaging capability and photothermal conversion capacity, respectively. The in vivo near-infrared (NIR) fluorescent images of A549-bearing mice injected with Cy5.5&ICG@ZIF-8-Dex demonstrated sufficient accumulations of Cy5.5 at tumor sites due to the enhanced permeability and retention effect. Most impressively, the fluorescent intensity of Cy5.5&ICG@ZIF-8-Dex at tumor site was approximately 40-fold higher than that of free Cy5.5. Additionally, the results of in vivo infrared imaging and photothermal therapy of Cy5.5&ICG@ZIF-8-Dex showed enhanced therapeutic efficiency in comparison with free ICG, further confirming its tumor-targeting capability and photothermal capacity. Therefore, this multifunctional system based on ZIF-8 nanocarriers offered a potential nanoplatform for tumor-targeting theranostics, thus broadening the synthesis and applications of ZIF-8 composite nanoparticles for NIR fluorescence imaging and photothermal therapy in the biomedical field. STATEMENT OF SIGNIFICANCE: Simultaneous immobilization of hydrophilic and hydrophobic molecules into ZIF-8 nanoparticles still remains a daunting challenge. Therefore, we have developed a new synthesis/encapsulation two-in-one approach to synthesize uniform Cy5.5&ICG@ZIF-8-Dex composite nanoparticles in DMSO/H₂O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) functional molecules during a single step. The results showed that the co-loading of Cy5.5 and ICG within the ZIF-8 nanoparticles endowed them with a remarkable fluorescence imaging capability and photothermal conversion capacity. Based on their enhanced convenience and efficacy to simultaneously encapsulate hydrophilic and hydrophobic molecules, the multifunctional nanocarriers that were prepared in the DMSO/H₂O mixed solvents provide a potential nanoplatform toward fluorescence imaging and photothermal therapy for tumor theranostics.

Recent development of metal-organic framework nanocomposites for biomedical applications

Albeit metal-organic framework (MOF) composites have been extensively explored, reducing the size and dimensions of various contents within the composition, to the nanoscale regime, has recently presented unique opportunities for enhanced properties with the formation of MOF-based nanocomposites. Many distinctive strategies have been used to fabricate these nanocomposites such as through the introduction of nanoparticles (NPs) into a MOF precursor solution or vice versa to achieve a core-shell or heterostructure configuration. As such, MOF-based nanocomposites offer seemingly limitless possibilities and promising solutions for the vast range of applications across biomedical disciplines especially for improving in vivo implementation. In this review, we focus on the recent development of MOF-based nanocomposites, outline their classification according to the type of integrations (NPs, coating materials, and different MOF-derived nanocomposites), and direct special attention towards the various approaches and strategies employed to construct these nanocomposites for their prospective utilization in biomedical applications including biomimetic enzymes and photo, chemo, sonodynamic, starvation and hyperthermia therapies. Lastly, our work aims to highlight the exciting potential as well as the challenges of MOF-based nanocomposites to help guide future research as well as to contribute to the progress of MOF-based nanotechnology in biomedicine.

Photocatalytic degradation of tetracycline by metal-organic frameworks modified with Bi2WO6 nanosheet under direct sunlight

Porous metal-organic frameworks (MOFs) with visible-light response have attracted much attention in the field of environmental purification and solar energy conversion. In this study, MIL-100(Fe) was modified with Bi₂WO₆ nanosheets by a facile hydrothermal method to fabricate a photocatalyst with direct Z-scheme heterojunction. When treating the tetracycline (TC) solution under natural sunlight, 12 wt%MIL-100(Fe)/Bi₂WO₆ obtained the highest apparent rate constant of (6.59 ± 0.52)✕10^-3 L mg^-1 min^-1, which was 16.1 and 3.9 times than that of pristine MIL-100(Fe) and Bi₂WO₆, respectively. In addition to explore the feasibility of sunlight-activated MIL-100(Fe)/Bi₂WO₆ to remove TC under various conditions, the degradation intermediates and their possible transformation pathway were provided with the aid of three-dimensional excitation-emission matrix spectra and liquid chromatography-mass spectrometry system. The results of Escherichia coli culture demonstrated that the biotoxicity variation of TC solution would first increase and then decrease with the photodegradation time. Ultimately, based on the results of bandgap calculation, radicals trapping and charge flow tracking experiments, the direct Z-scheme heterojunction between MIL-100(Fe) and Bi₂WO₆ nanosheets was confirmed and the photocatalytic mechanism for TC degradation was rationally proposed. This work enriched MOFs-based heterojunction photocatalysts and provided a promising method to eliminate hazardous TC from aqueous solution.

Molecular Probes for Autofluorescence-Free Optical Imaging

Optical imaging is an indispensable tool in clinical diagnostics and fundamental biomedical research. Autofluorescence-free optical imaging, which eliminates real-time optical excitation to minimize background noise, enables clear visualization of biological architecture and physiopathological events deep within living subjects. Molecular probes especially developed for autofluorescence-free optical imaging have been proven to remarkably improve the imaging sensitivity, penetration depth, target specificity, and multiplexing capability. In this Review, we focus on the advancements of autofluorescence-free molecular probes through the lens of particular molecular or photophysical mechanisms that produce long-lasting luminescence after the cessation of light excitation. The versatile design strategies of these molecular probes are discussed along with a broad range of biological applications. Finally, challenges and perspectives are discussed to further advance the next-generation autofluorescence-free molecular probes for in vivo imaging and in vitro biosensors.

Effects of Zeolite as a Drug Delivery System on Cancer Therapy: A Systematic Review

Zeolites and zeolitic imidazolate frameworks (ZIFs) are widely studied as drug carrying nanoplatforms to enhance the specificity and efficacy of traditional anticancer drugs. At present, there is no other systematic review that assesses the potency of zeolites/ZIFs as anticancer drug carriers. Due to the porous nature and inherent pH-sensitive properties of zeolites/ZIFs, the compounds can entrap and selectively release anticancer drugs into the acidic tumor microenvironment. Therefore, it is valuable to provide a comprehensive overview of available evidence on the topic to identify the benefits of the compound as well as potential gaps in knowledge. The purpose of this study was to evaluate the potential therapeutic applications of zeolites/ZIFs as drug delivery systems delivering doxorubicin (DOX), 5-fluorouracil (5-FU), curcumin, cisplatin, and miR-34a. Following PRISMA guidelines, an exhaustive search of PubMed, Scopus, Embase, and Web of Science was conducted. No language or time limitations were used up to 25th August 2021. Only full text articles were selected that pertained to the usage of zeolites/ZIFs in delivering anticancer drugs. Initially, 1279 studies were identified, of which 572 duplicate records were excluded. After screening for the title, abstract, and full texts, 53 articles remained and were included in the qualitative synthesis. An Inter-Rater Reliability (IRR) test, which included a percent user agreement and reliability percent, was conducted for the 53 articles. The included studies suggest that anticancer drug-incorporated zeolites/ZIFs can be used as alternative treatment options to enhance the efficacy of cancer treatment by mitigating the drawbacks of drugs under conventional treatment.

Nanoscale Metal-Organic Frameworks: Recent developments in synthesis, modifications and bioimaging applications

Porous Metal-Organic Frameworks (MOFs) have emerged as eye-catching materials in recent years. They are widely used in numerous fields of chemistry thanks to their desirable properties. MOFs have a key role in the development of bioimaging platforms that are hopefully expected to effectually pave the way for accurate and selective detection and diagnosis of abnormalities. Recently, many types of MOFs have been employed for detection of RNA, DNA, enzyme activity and small-biomolecules, as well as for magnetic resonance imaging (MRI) and computed tomography (CT), which are valuable methods for clinical analysis. The optimal performance of the MOF in the bio-imaging field depends on the core structure, synthesis method and modifications processes. In this review, we have attempted to present crucial parameters for designing and achieving an efficient MOF as bioimaging platforms, and provide a roadmap for researchers in this field. Moreover, the influence of modifications/fractionalizations on MOFs performance has been thoroughly discussed and challenging problems have been extensively addressed. Consideration is mainly focused on the principal concepts and applications that have been achieved to modify and synthesize advanced MOFs for future applications.

[Research progress in application of metal-organic framework-derived materials to sample pretreatment]

Sample pretreatment technology plays a vital role throughout the analysis of complex samples. Sample pretreatment can not only increase the concentration of trace targets in the sample, but also effectively eliminate interference from the sample matrix in instrumental analysis. Adsorbent materials are a key component of sample pretreatment technology. Therefore, the development of efficient and stable new adsorbent materials has acquired significance in research on pretreatment technology. Porous materials are advantageous for use in diverse applications, such as in adsorbents, when they possess controllable nanostructures, a tailored pore surface chemistry, and abundant porosity, and are inexpensive. Particularly in recent years, porous materials derived from metal-organic frameworks (MOFs) feature excellent properties, such as diverse morphology and structure, adjustable pore size, high specific surface area, good thermal stability, and chemical resistance. MOF-derived materials, when used as adsorbents for sample pretreatment, offer the following advantages: (1) The porous materials derived from MOFs typically possess a larger specific surface area than other porous materials. This characteristic is beneficial to improve the extraction capacity and extraction efficiency via an increase in the contact area between the materials and targets; (2) The microscopic porous structure of MOF-derived materials can be easily tuned (by controlling the temperature and time during pyrolysis, gas atmosphere, and heating rate), which is conducive to improve the selectivity of sample pretreatment methods; (3) The metal active sites can be evenly distributed. Owing to the ordered distribution of metal ions in the precursor MOFs and a good periodic framework structure, the metal active sites of the derivatives formed can still maintain a corresponding distance. These metal active sites will not form agglomerates and affect the extraction performance; conversely, other porous materials often require extremely complicated processes to achieve a uniform distribution; (4) Heteroatoms such as nitrogen and sulfur can be easily doped on the framework of MOF-derived porous materials. This doping enables the materials to induce additional interactions such as hydrogen bonding and π-π stacking for adsorbing target analytes. The excellent properties of MOF-derived materials make them promising for use in sample pretreatment. Novel sample pretreatment methods that use MOF-derived materials are constantly being developed. However, the use of MOF-derived materials is limited by the complex preparation process and high production cost of MOF precursors, along with difficulties in mass production. Further, the precise design or functionalization of MOF-derived materials according to the characteristics of targets is a new direction with immense challenges as well as application potential. This review summarizes the application of MOF-derived materials in sample pretreatment methods, including dispersive solid phase extraction (dSPE), magnetic solid phase extraction (MSPE), solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), and dispersive micro solid phase extraction (DMSPE). The preparation methods, functional control, and enrichment efficiencies of various MOF-derived materials are also reviewed. Finally, the application prospects of MOF-derived materials in sample pretreatment are discussed to provide a clear outlook and reference for further related research.

Mixed Solvent Method for Improving the Size Uniformity and Cargo-Loading Efficiency of ZIF-8 Nanoparticles

Zeolitic imidazolate framework-8 (ZIF-8) nanoparticles with tunable diameters and a uniform morphology were constructed in dimethyl sulfoxide (DMSO)/H₂O mixed solvents and were further decorated with dextran to improve their stability and biocompatibility. A series of reaction conditions, including the DMSO content in mixed solvents, molar ratio between precursors, growth time, and decoration of dextran, were systematically investigated. Most importantly, it was the union of DMSO and water that achieved the combined merits of both solvothermal and hydrothermal methods, namely, high uniformity and high efficiency, respectively. In addition, numerous properties of these ZIF-8 nanoparticles were subsequently studied, such as the crystal structure, surface properties, and porosity. Furthermore, composite ZIF-8 nanoparticles encapsulating various functional molecules were also successfully prepared in the same DMSO/H₂O mixed solvents, thus laying the foundation for their application as nanocarriers in the biomedical field.

Biodegradable manganese engineered nanocapsules for tumor-sensitive near-infrared persistent luminescence/magnetic resonance imaging and simultaneous chemotherapy

Rationale: Near-Infrared persistent luminescence (NIR-PL) nanomaterials that can continually emit low-energy photons after ceasing excitation has emerged as a new generation of theranostic nanoparticle drug delivery systems (NDDSs) for imaging-guided cancer therapy, which stems from their special ability to completely avoid tissue autofluorescence interference. However, unresponsive diagnostic capability, inefficient drug delivery, and poor biodegradability limit the efficacy of most reported NIR-PL-based NDDSs. Methods: Herein, a multifaceted tumor microenvironment (TME)-degradable theranostic drug delivery nanocapsule based on an ultrasmall persistent phosphor with a hollow mesoporous manganese-doped, DOX-loaded silica shell (Mn-ZGOCS-PEG) is developed to overcome the above drawbacks. Results: We demonstrate that the well-designed nanocapsule enables tumor-responsive controlled drug release with ameliorated therapeutic efficacy, TME-responsive autofluorescence interference-free NIR-PL tracing, and manganese-enhanced magnetic resonance (Mn-MR) monitoring for practical dual-modality image-guided antitumor treatment in vivo. Conclusion: Our results indicate that Mn-ZGOCS-PEG nanocapsules enable tumor-targeting augmented chemotherapy under the guidance of TME-responsive dual-MR/NIR-PL-modality imaging in vivo. We believe that our work provides a new paradigm for the development of smart NIR-PL-based NDDSs with ultrasensitive multimodal diagnostic capability, enhanced anticancer effect, and efficient biodegradability.

Persistent luminescence nanorods-based autofluorescence-free biosensor for prostate-specific antigen detection

Persistent luminescent nanoparticles (PLNPs) are a class of materials with excellent optical properties, which can continue to emit light for a long time after removing the excitation light source. This feature enables PLNPs to be used for development of biological detection modes without autofluorescence background. In this study, we prepared Zn₂GeO₄: Mn²⁺, Pr³⁺ (ZGOMP) nanorods through a one-pot hydrothermal method. Using the pH-responsive luminescence behavior of ZGOMP, we developed an autofluorescence-free biosensor using ZGOMP as a probe and gluconic acid as a quencher to detect prostate-specific antigen (PSA). Hybridization chain reaction (HCR) and magnetic separation system were introduced in the design to achieve efficient signal amplification. Under the optimal conditions, the as-designed autofluorescence-free sensing platform showed high selectivity, and showed a good luminescence response to PSA within the linear range of 0.001-10 ng/mL at a detection limit of 0.64 pg/mL. The excellent analytical performance shows that the current strategy provides an effective platform for clinical sample analysis.

Persistent luminescence nanoparticles for cancer theranostics application

Persistent luminescence nanoparticles (PLNPs) are unique optical materials that emit afterglow luminescence after ceasing excitation. They exhibit unexpected advantages for in vivo optical imaging of tumors, such as autofluorescence-free, high sensitivity, high penetration depth, and multiple excitation sources (UV light, LED, NIR laser, X-ray, and radiopharmaceuticals). Besides, by incorporating other functional molecules, such as photosensitizers, photothermal agents, or therapeutic drugs, PLNPs are also widely used in persistent luminescence (PersL) imaging-guided tumor therapy. In this review, we first summarize the recent developments in the synthesis and surface functionalization of PLNPs, as well as their toxicity studies. We then discuss the in vivo PersL imaging and multimodal imaging from different excitation sources. Furthermore, we highlight PLNPs-based cancer theranostics applications, such as fluorescence-guided surgery, photothermal therapy, photodynamic therapy, drug/gene delivery and combined therapy. Finally, future prospects and challenges of PLNPs in the research of translational medicine are also discussed.

Applications of nanoscale metal-organic frameworks as imaging agents in biology and medicine

Nanoscale metal-organic frameworks (NMOFs) are an interesting and unique class of hybrid porous materials constructed by the self-assembly of metal ions/clusters with organic linkers. The high storage capacities, facile synthesis, easy surface functionalization, diverse compositions and excellent biocompatibilities of NMOFs have made them promising agents for theranostic applications. By combination of a large variety of metal ions and organic ligands, and incorporation of desired molecular functionalities including imaging modalities and therapeutic molecules, diverse MOF structures with versatile functionalities can be obtained and utilized in biomedical imaging and drug delivery. In recent years, NMOFs have attracted great interest as imaging agents in optical imaging (OI), magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET) and photoacoustic imaging (PAI). Furthermore, the significant porosity of MOFs allows them to be loaded with multiple imaging agents and therapeutics simultaneously and applied for multimodal imaging and therapy as a single entity. In this review, which is intended as an introduction to the use of MOFs in biomedical imaging for a reader entering the subject, we summarize the up-to-date progress of NMOFs as bioimaging agents, giving (i) a broad perspective of the varying imaging techniques that MOFs can enable, (ii) the different routes to manufacturing functionalised MOF nanoparticles and hybrids, and (iii) the integration of imaging with differing therapeutic techniques. The current challenges and perspectives of NMOFs for their further clinical translation are also highlighted and discussed.

Recent advances in persistent luminescence based on molecular hybrid materials

Molecular persistently luminescent materials have received recent attention due to their promising applications in optical displays, biological imaging, chemical sensing, and security systems. In this review, we systematically summarize recent advances in establishing persistently luminescent materials-specifically focusing on materials composed of molecular hybrids for the first time. We describe the main strategies for synthesizing these hybrid materials, namely: (i) inorganics/organics, (ii) organics/organics, and (iii) organics/polymer systems and demonstrate how molecular hybrids provide synergistic effects, while improving luminescence lifetimes and efficiencies. These hybrid materials promote new methods for tuning key physical properties such as singlet-triplet excited state energies by controlling the chemical interactions and molecular orientations in the solid state. We review new advances in these materials from the perspective of examining experimental and theoretical approaches to room-temperature phosphorescence and thermally-activated delayed fluorescence. Finally, this review concludes by summarizing the current challenges and future opportunities for these hybrid materials.

Stimuli-responsive metal-organic framework nanoparticles for controlled drug delivery and medical applications

Stimuli-responsive metal-organic framework nanoparticles, NMOFs, provide a versatile platform for the controlled release of drugs and biomedical applications. The porous structure of NMOFs, their biocompatibility, low toxicity, and efficient permeability turn the NMOFs into ideal carriers for therapeutic applications. Two general methods to gate the drug-loaded NMOFs and to release the loads were developed: by one method, the loaded NMOFs are coated or surface-modified with stimuli-responsive gates being unlocked in the presence of appropriate chemical (e.g., ions or reducing agents), physical (e.g., light or heat), or biomarker (e.g., miRNA or ATP) triggers. By a second approach, the drug-loaded NMOFs include encoded structural information or co-added agents to induce the structural distortion or stimulate the degradation of the NMOFs. Different chemical triggers such as pH changes, ions, ATP, or redox agents, and physical stimuli such as light or heat are applied to degrade the NMOFs, resulting in the release of the loads. In addition, enzymes, DNAzymes, and disease-specific biomarkers are used to unlock the gated NMOFs. The triggered release of drugs for cancer therapy, anti-blood clotting, and the design of autonomous insulin-delivery systems ("artificial pancreas") are discussed. Specifically, multi-drug carrier systems and functional NMOFs exhibiting dual and cooperative therapeutic functions are introduced. The future perspectives and applications of stimuli-responsive particles are addressed.

Supramolecular metal-based nanoparticles for drug delivery and cancer therapy

Although conventional cancer therapies such as chemotherapy and radiotherapy prevail in clinic, they tend to have narrow therapeutic windows. Many chemotherapies have unfavorable pharmacokinetics while radiotherapy incurs radiotoxicity to normal tissues surrounding tumors. The chemical tunability of supramolecular metal-based nanoparticles (SMNPs) enables the incorporation of various therapeutics, including hydrophilic and hydrophobic chemotherapeutic drugs, photosensitizers, radiosensitizers, and biological therapeutics for more effective delivery to tumors. In this mini-review, we highlight recent advances in SMNPs, namely nanoscale coordination polymers and nanoscale metal-organic frameworks, for drug delivery and cancer therapy. We particularly focus on innovative uses of metal clusters, ligands, pores, and surface modifications to load various therapeutics into SMNPs and critical evaluations of the anticancer efficacies of SMNPs.

Dual Roles of Metal-Organic Frameworks as Nanocarriers for miRNA Delivery and Adjuvants for Chemodynamic Therapy

MicroRNA (miRNA) represents a promising class of therapeutic nucleic acid drugs, while delivery challenges remain that impede the advancement of miRNA therapy, largely because of in vivo instability and low delivery efficiency. Herein, we discover the dual roles of metal-organic framework (MOF) nanoparticles (ZIF-8) as nanocarriers for miRNA delivery and adjuvants for chemodynamic therapy. The miR-34a-m@ZIF-8 complex demonstrated efficient cellular uptake and lysosomal stimuli-responsive miRNA release. Zn²⁺ triggered the generation of reactive oxygen species, which consequently induced apoptosis of tumor cells. Released miR-34a-m led to a remarkable decrease in expression of Bcl-2 at both mRNA and protein levels and enhanced cancer cell apoptosis. In vivo experiments showed high efficacy of using miR-34a-m@ZIF-8 to suppress tumor growth via synergistic gene/chemodynamic therapy in a mouse model of triple-negative breast cancer. Our work demonstrates MOFs as a promising nanoplatform for efficient synergetic gene/chemodynamic therapy.

Yolk–shell magnetic composite Fe3O4@Co/Zn-ZIF for MR imaging-guided chemotherapy of tumors in vivo

The yolk–shell composites Fe₃O₄@Co/Zn-ZIF exhibited high doxorubicin loading capacity, pH-responsive release characteristics, and strong T₂-weighted MR imaging contrast enhancement, and were used for MR imaging-guided chemotherapy of tumors in vivo.

Smart metal organic frameworks: focus on cancer treatment

Metal–organic frameworks (MOFs), as a prominent category of hybrid porous materials, have been broadly employed as controlled systems of drug delivery due to their inherent interesting properties.

CuFeSe2-based thermo-responsive multifunctional nanomaterial initiated by a single NIR light for hypoxic cancer therapy

A thermo-responsive CuFeSe₂-based multifunctional nanomaterial was used for NIR light initiated hypoxic cancer therapy and CT/MR imaging.

Synthesis and Biomedical Applications of Lanthanides-Doped Persistent Luminescence Phosphors With NIR Emissions

Persistent luminescence phosphors (PLPs) are largely used in biomedical areas owing to their unique advantages in reducing the autofluorescence and light-scattering interference from tissues. Moreover, PLPs with long-lived luminescence in the near-infrared (NIR) region are able to be applied in deep-tissue bioimaging or therapy due to the reduced light absorption of tissues in NIR region. Because of their abundant election levels and energy transfer channels, lanthanides are widely doped in PLPs for the generation of NIR persistent emissions. In addition, the crystal defects introduced by lanthanides-doping can serves as charge traps in PLPs, which contributes to the enhancement of persistent luminescence intensity and the increase of persistent time. In this paper, the research progress in the synthesis and biomedical applications of lanthanides-doped PLPs with NIR emissions are systematically summarized, which can provide instructions for the design and applications of PLPs in the future.

Metal-organic frameworks for virus detection

Virus severely endangers human life and health, and the detection of viruses is essential for the prevention and treatment of associated diseases. Metal-organic framework (MOF), a novel hybrid porous material which is bridged by the metal clusters and organic linkers, has become a promising biosensor platform for virus detection due to its outstanding properties including high surface area, adjustable pore size, easy modification, etc. However, the MOF-based sensing platforms for virus detection are rarely summarized. This review systematically divided the detection platforms into nucleic acid and immunological (antigen and antibody) detection, and the underlying sensing mechanisms were interpreted. The nucleic acid sensing was discussed based on the properties of MOF (such as metal ion, functional group, geometry structure, size, porosity, stability, etc.), revealing the relationship between the sensing performance and properties of MOF. Moreover, antibodies sensing based on the fluorescence detection and antigens sensing based on molecular imprinting or electrochemical immunoassay were highlighted. Furthermore, the remaining challenges and future development of MOF for virus detection were further discussed and proposed. This review will provide valuable references for the construction of sophisticated sensing platform for the detection of viruses, especially the 2019 coronavirus.

Coloring Afterglow Nanoparticles for High-Contrast Time-Gating-Free Multiplex Luminescence Imaging

Afterglow nanoparticles (AGNPs) possessing inherently long lifetime with tailorable emission colors and uniform size have long been sought due to their time-gating-free high-contrast multiplexing imaging. Herein, via a straightforward template method, it is reported that such multicolor AGNPs can be accomplished. The resultant AGNPs exhibit a series of tunable afterglow emissions, including blue, yellow, green, and white. These multicolor AGNPs are found to be highly bright, enabling them to perform high-contrast multichannel afterglow imaging in vitro and in vivo without the use of any complicated time-gating algorithms or systems, which existing tools are unable to do.

Novel Protease-Free Long-Lasting Chemiluminescence System Based on the Dox-ABEI Chimeric Magnetic DNA Hydrogel for Ultrasensitive Immunoassay

Most of chemiluminescence (CL) substrates exhibit the flash-type light emission. Therefore, the long-lasting CL system is always the crown in the field of CL-based analysis methodology. In this work, we constructed a Dox-ABEI chimeric magnetic DNA hydrogel (MDH) as a novel protease-free long-lasting CL reaction system. The functional MDH can transform flash-type ABEI/H₂O₂/CO²⁺ reaction into a glow-type CL system because of its block effect on delaying the diffusion rate of co-reactants, making the CL reaction gradually occur. More importantly, the functional MDH possessed the advantages of biocompatibility and controllability and could be well-designed to incorporate different biosensing strategies. Subsequently, we established a functional MDH-based long-lasting CL immunoassay system for ultrasensitive and highly specific detection of d-dimer and fibrin degradation products (FDPs). The designed CL immunoassay can detect d-dimer and FDP down to 53.7 and 31.6 fg/mL, respectively, with a wide line ranging from 100 fg/mL to 100 ng/mL, which was superior to the previously reported CL biosensing strategies. Moreover, benefiting from the magnetic separation of MDH and excellent CL performance, the developed immunoassaying method was successfully applied in the detection of clinical samples, which showed a close correlation with clinical reference technology. Thus, this functional MDH proved to be an excellent long-lasting CL system and a potential technical platform for clinical bioanalysis applications.