Enhanced theranostic efficacy of epirubicin-loaded SPION@MSN through co-delivery of an anti-miR-21-expressing plasmid and ZIF-8 hybridization to target colon adenocarcinoma

Using targeted drug delivery systems has emerged as a promising approach to increase the efficacy of chemotherapy, particularly in combination with gene therapy. The overexpression of miR-21 plays a crucial role in colorectal cancer (CRC) progression, and targeted inhibition of miR-21 offers significant potential for enhancing CRC chemotherapy outcomes. In this study, a theranostic system based on mesoporous silica and superparamagnetic iron oxide nanoparticles (SPION@MSNs) was synthesized as a core-shell structure. After loading epirubicin (EPI) in the open pores of MSN, the plasmid expressing anti-miR-21 (pDNA) covered the outer surface with the help of a ZIF-8 (zeolitic imidazolate framework-8) film. Afterward, polyethylene glycol (PEG) and AS1411 aptamer were conjugated to the surface to improve the protective, biocompatibility, and targeting abilities of the nanocarrier. Moreover, the physicochemical characteristics as well as the loading capacity and release profile of EPI and pDNA were fully evaluated. The uptake of the nanoparticles by CRC and normal cell lines in addition to the anticancer effects related to targeted combinational therapy were investigated in vitro. Finally, in vivo tests were performed on BALB/c mice bearing colorectal tumors to evaluate the effectiveness of the targeted nanoparticles, their possible side effects, and also their application in fluorescence and magnetic imaging in vivo. The successful synthesis of SPION@MSN-EPI/pDNA-ZIF-8-PEG-Apt nanoparticles (∼68 nm) and good loading efficiency and controlled release of EPI and pDNA were confirmed. Moreover, hemolysis and gel retardation assays demonstrated the biocompatibility and plasmid protection. Cellular uptake and expression of copGFP illustrated selective entry and transient transfection of targeted nanoparticles, consistent with the cytotoxicity results that indicated the synergistic effects of chemo-gene therapy. The results of animal studies proved the high antitumor efficiency of targeted nanoparticles with minimal tissue damage, which was in line with fluorescence and magnetic imaging results. The novel synthesized nanoparticles containing SPION@MSN-ZIF-8 were suitable for CRC theranostics, and the combined approach of chemo-gene therapy suppressed the tumor more effectively.

Core-shell inorganic NP@MOF nanostructures for targeted drug delivery and multimodal imaging-guided combination tumor treatment

It is well known that metal-organic framework (MOF) nanostructures have unique characteristics such as high porosity, large surface areas and adjustable functionalities, so they are ideal candidates for developing drug delivery systems (DDSs) as well as theranostic platforms in cancer treatment. Despite the large number of MOF nanostructures that have been discovered, conventional MOF-derived nanosystems only have a single biofunctional MOF source with poor colloidal stability. Accordingly, developing core-shell MOF nanostructures with good colloidal stability is a useful method for generating efficient drug delivery, multimodal imaging and synergistic therapeutic systems. The preparation of core-shell MOF nanostructures has been done with a variety of materials, but inorganic nanoparticles (NPs) are highly effective for drug delivery and imaging-guided tumor treatment. Herein, we aimed to overview the synthesis of core-shell inorganic NP@MOF nanostructures followed by the application of core-shell MOFs derived from magnetic, quantum dots (QDs), gold (Au), and gadolinium (Gd) NPs in drug delivery and imaging-guided tumor treatment. Afterward, we surveyed different factors affecting prolonged drug delivery and cancer therapy, cellular uptake, biocompatibility, biodegradability, and enhanced permeation and retention (EPR) effect of core-shell MOFs. Last but not least, we discussed the challenges and the prospects of the field. We envision this article may hold great promise in providing valuable insights regarding the application of hybrid nanostructures as promising and potential candidates for multimodal imaging-guided combination cancer therapy.

A Versatile G-Quadruplex (G4)-Coated Upconverted Metal-Organic Framework for Hypoxic Tumor Therapy

Given the complexity of the tumor microenvironment, multiple strategies are being explored to tackle hypoxic tumors. The most efficient strategies combine several therapeutic modalities and typically requires the development of multifunctional nanocomposites through sophisticated synthetic procedures. Herein, the G-quadruplex (G4)-forming sequence AS1411-A (d[(G2 T)4 TG(TG2 )4 A]) is used for both its anti-tumor and biocatalytic properties when combined with hemin, increasing the production of O2 ca. two-fold as compared to the parent AS1411 sequence. The AS1411-A/hemin complex (GH) is grafted on the surface and pores of a core-shell upconverted metal-organic framework (UMOF) to generate a UMGH nanoplatform. Compared with UMOF, UMGH exhibits enhanced colloidal stability, increased tumor cell targeting and improved O2 production (8.5-fold) in situ. When irradiated by near-infrared (NIR) light, the UMGH antitumor properties are bolstered by photodynamic therapy (PDT), thanks to its ability to convert O2 into singlet oxygen (1 O2 ). Combined with the antiproliferative activity of AS1411-A, this novel approach lays the foundation for a new type of G4-based nanomedicine.

A computational study of metal-organic frameworks (MOFs) as potential nanostructures to combat SARS-CoV-2

The COVID-19 causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has a critical surface protein called spike protein (S protein), which is the target of many vaccines and drugs developments. Among non-structural proteins of SARS-CoV-2, main protease (M^pro) has drawn much attention to itself for designing antiviral drugs since it is very crucial for the virus replication in host cells. In the first part of the present study, the application of metal-organic frameworks (MOFs), one of the developing nanomaterials in the deformation and consequently inhibition of S protein binding to the receptor, angiotensin-converting enzyme 2 (ACE 2), is investigated. In this line, various S protein inhibitors were designed virtually, including ZIF, UIO, and IRMOF that their interactions with S protein and were investigated using molecular dynamics (MD) simulation. The results revealed that ZIF is the best candidate among the investigated MOFs with the least amount of energy interference with S protein. In the second part, the interaction of three-dimensional (3D) MOFs (such as ZIF, IRMOF, and HKUST) with SARS-CoV-2 M^pro was investigated. HKUST had the most potent interaction with M^pro and showed more promise in deforming this protein's secondary structure among all materials tested. Furthermore, we investigated the interaction of HKUST-OH with M^pro to determine the effect of functionalization. The findings of this study could be used in future studies to introduce bioconjugates of MOFs and biological molecules (e.g., antibody or nanobody) or to use MOFs as carriers for antiviral drug delivery.

Metal organic frameworks (MOFS) as non-viral carriers for DNA and RNA delivery: a review

Metal-Organic Frameworks (MOFs) are a class of crystalline materials that, thanks to their large surface area and high porosity, allow them to be used in various areas of knowledge. This diversity of applications is due to the metal ions and the organic binders that compose them, but it is also important to highlight the ability of MOFs to function as hosts for a great variety of molecules of very different sizes and chemical properties. The first existing approaches for incorporating biomolecules in MOFs are discussed: pore encapsulation, surface binding, covalent binding, and in-situ encapsulation. Next, we discuss the obstacles of designing MOFs for effective gene delivery and how to enhance the gene delivery using different strategies.

Combinational application of metal-organic frameworks-based nanozyme and nucleic acid delivery in cancer therapy

The rapid development of nanotechnology has generated numerous ideas for cancer treatment, and a wide variety of relevant nanoparticle platforms have been reported. Metal-organic frameworks (MOFs) have been widely investigated as an anti-cancer drug delivery vehicle owing to their unique porous hybrid structure, biocompatibility, structural tunability, and multi-functionality. MOF materials with catalytic activity, known as nanozymes, have applications in photodynamic and chemodynamic therapy. Nucleic acids have also attracted increasing research attention owing to their programmability, ease of synthesis, and versatility. A variety of functional DNAs and RNAs have been applied both therapeutically (gene-targeting drugs for cancer treatment) and nontherapeutically (used as modified materials to enhance the therapeutic effects of other nanomedicines). The combined use of MOFs and functional nucleic acids have been extensively investigated and has been associated with excellent tumor-suppressor activity in various treatment methods. In this review, we summarize the progress in the research and development of tumor therapy based on MOFs and nucleic acid delivery over recent years, focusing on the combinational use of different delivery and design strategies for MOF/therapeutic nucleic acid platforms. We further summarize the strategies for combining MOFs (universal carrier, functional carrier) and nucleic acids (therapeutic nucleic acids, nontherapeutic nucleic acids) and discuss the corresponding therapeutic effects in cancer treatment. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Polymer-Coated NH2-UiO-66 for the Codelivery of DOX/pCRISPR

Herein, the NH₂-UiO-66 metal organic framework (MOF) has been green synthesized with the assistance of high gravity to provide a suitable and safe platform for drug loading. The NH₂-UiO-66 MOF was characterized using a field-emission scanning electron microscope, transmission electron microscope (TEM), X-ray diffraction, and zeta potential analysis. Doxorubicin was then encapsulated physically on the porosity of the green MOF. Two different stimulus polymers, p(HEMA) and p(NIPAM), were used as the coating agents of the MOFs. Doxorubicin was loaded onto the polymer-coated MOFs as well, and a drug payload of more than 51% was obtained, which is a record by itself. In the next step, pCRISPR was successfully tagged on the surface of the modified MOFs, and the performance of the final nanosystems were evaluated by the GFP expression. In addition, successful loadings and internalizations of doxorubicin were investigated via confocal laser scanning microscopy. Cellular images from the HeLa cell line for the UiO-66@DOX@pCRISPR and GMA-UiO-66@DOX@pCRISPR do not show any promising and successful gene transfections, with a maximum EGFP of 1.6%; however, the results for the p(HEMA)-GMA-UiO-66@DOX@pCRISPR show up to 4.3% transfection efficiency. Also, the results for the p(NIPAM)-GMA-UiO-66@DOX@pCRISPR showed up to 6.4% transfection efficiency, which is the first and superior report of a MOF-based nanocarrier for the delivery of pCRISPR. Furthermore, the MTT assay does not shown any critical cytotoxicity, which is a promising result for further biomedical applications. At the end of the study, the morphologies of all of the nanomaterials were screened after drug and gene delivery procedures and showed partial degradation of the nanomaterial. However, the cubic structure of the MOFs has been shown in TEM, and this is further proof of the stability of these green MOFs for biomedical applications.

Growth of ZIF-8 MOF Films with Tunable Porosity by using Poly (1-vinylimidazole) Brushes as 3D Primers

This work reports on a novel and versatile approach to control the structure of metal-organic framework (MOFs) films by using polymeric brushes as 3D primers, suitable for triggering heterogeneous MOF nucleation. As a proof-of-concept, this work explores the use of poly(1-vinylimidazole) brushes primer obtained via surface-initiated atom transfer radical polymerization (SI-ATRP) for the synthesis of Zn-based ZIF-8 MOF films. By modifying the grafting density of the brushes, smooth porous films were obtained featuring inherently hydrophobic microporosity arising from ZIF-8 structure, and an additional constructional interparticle mesoporosity, which can be employed for differential adsorption of targeted adsorbates. It was found that the grafting density modulates the constructional porosity of the films obtained; higher grafting densities result in more compact structures, while lower grafting density generates increasingly inhomogeneous films with a higher proportion of interparticle constructional porosity.

Polymer/Metal Organic Framework (MOF) Nanocomposites for Biomedical Applications

The utilization of polymer/metal organic framework (MOF) nanocomposites in various biomedical applications has been widely studied due to their unique properties that arise from MOFs or hybrid composite systems. This review focuses on the types of polymer/MOF nanocomposites used in drug delivery and imaging applications. Initially, a comprehensive introduction to the synthesis and structure of MOFs and bio-MOFs is presented. Subsequently, the properties and the performance of polymer/MOF nanocomposites used in these applications are examined, in relation to the approach applied for their synthesis: (i) non-covalent attachment, (ii) covalent attachment, (iii) polymer coordination to metal ions, (iv) MOF encapsulation in polymers, and (v) other strategies. A critical comparison and discussion of the effectiveness of polymer/MOF nanocomposites regarding their synthesis methods and their structural characteristics is presented.

Construction of an iridium(iii)-complex-loaded MOF nanoplatform mediated with a dual-responsive polycationic polymer for photodynamic therapy and cell imaging

A multifunctional nanoplatform was constructed using an UiO-66-based MOF, an Ir(iii) complex and a dual-responsive polymer to achieve efficient PDT and bioimaging.

A γ-cyclodextrin-based metal-organic framework embedded with graphene quantum dots and modified with PEGMA via SI-ATRP for anticancer drug delivery and therapy

The γ-cyclodextrin-based metal-organic framework (γ-CD-MOF) composite was designed and prepared toward targeted anticancer drug delivery and cancer therapy. Large amounts of graphene quantum dots (GQDs) were embedded in the γ-CD-MOF matrix (denoted as GQDs@γ-CD-MOF) to endow the γ-CD-MOF with strong fluorescence, which was then modified by pH responsive poly(ethyleneglycol)dimethacrylate (PEGMA) through surface initiated atom transfer radical polymerization (SI-ATRP) to fabricate the PEGMA@GQDs@γ-CD-MOF composite. Then, the cancer cell-targeted probe was obtained by immobilizing the AS1411 aptamer over it (denoted as AS1411@PEGMA@GQDs@γ-CD-MOF) and it exhibits pH-responsive release function and excellent targeting ability. Large amounts of antitumour drug, doxorubicin hydrochloride (DOX), could be encapsulated within this composite due to the chemical-rich functionality, and the resultant pH-responsive DOX delivery system (denoted as DOX/AS1411@PEGMA@GQDs@γ-CD-MOF) displayed a higher DOX loading of 89.1% with sustained release than the pristine γ-CD-MOF and GQDs@γ-CD-MOF. The targeting specificity investigation revealed that this DOX delivery system was effectively internalized via receptor mediated endocytosis with high selectivity. The in vivo antitumour study with tumour-bearing mice illustrated that the tumour growth can be effectively suppressed and partially ablated with negligible side effects after treatments. Therefore, the proposed AS1411@PEGMA@GQD@γ-CD-MOF composite is promising for effective DOX delivery and tumour growth inhibition both in vitro and in vivo, showing great potential for anticancer therapy.

Superoxide dismutase transcellular shuttle constructed from dendritic MOF and charge reversible protein derivatives

The development of molecular biology has led to the identification of protein-based therapeutics as an intriguing approach for the treatment of a wide range of diseases. To manufacture transcellular protein delivery shuttles, we attempted charge reversal chemistry on native proteins [e.g., superoxide dismutase (SOD): an enzyme capable of scavenging detrimental reactive oxygen species] by the selective conversion of the positively charged amino residues of native SOD to conjugated negatively charged citraconic moieties, eliciting overall negatively charged polyelectrolytes for the subsequent electrostatic self-assembly with cationic metal-organic framework (MOF) derivatives into protein delivery systems. Please note that the charge conversion was reversible, restoring the original amino groups in intracellular acidic endosome compartments (pH 5), which afforded facile charge reversible functions to reclaim the active SOD in the cell interior. In particular, the strategic manufacture of dendritic MOF supramolecular architectures as transcellular shuttles for the aforementioned charge-reversible SOD derivatives is noteworthy. The MOF was surface-functionalized with several polycationic segments, thus contributing to the hyper-charged architecture for the easy accommodation of the negatively charged SOD derivatives. Consequently, the SOD derivatives managed to internalize into cells by hitchhiking via endocytosis of the positively charged MOF. Once they resided in the acidic endosomes, the charge reversal of the SOD derivatives could occur smoothly and result in reduced interactions between the charged-reversed SOD and MOF, leading to the release of active SOD. Simultaneously, the dendritic MOF due to protein release presented a highly positive-charged architecture to provoke endosome membrane disruption, consequently spurring the translocation of SOD to the cytosol for the execution of its enzymatic activities. Herein, the intracellular ROS level of the activated macrophages was validated to be markedly suppressed by our proposed transcellular SOD shuttles, thereby indicating their wide availability to diverse functional proteins for biomedical applications.

A generalizable method for the construction of MOF@polymer functional composites through surface-initiated atom transfer radical polymerization

A universal method to grow polymers on MOF surfaces with well-defined thickness, sequence and functionality.

We report a generalizable approach to construct MOF@polymer functional composites through surface-initiated atom transfer radical polymerization (SI-ATRP). Unlike conventional SI-ATRP that requires covalent pre-anchoring of the initiating group on substrate surfaces, in our approach, a rationally designed random copolymer (RCP) macroinitiator first self-assembles on MOF surfaces through inter-chain hydrogen bond crosslinking. Subsequent polymerization in the presence of a crosslinking monomer covalently threads these polymer chains into a robust network, physically confining the MOF particle inside the polymer shell. We demonstrated the universality of this approach by growing various polymers on five MOFs of different metals (Zr, Zn, Co, Al, and Cr) with complete control over shell thickness, functionality and layer sequence while still retaining the inherent porosity of the MOFs. Moreover, the wettability of UiO-66 can be continuously tuned from superhydrophilic to superhydrophobic simply through judicious monomer(s) selection. We also demonstrated that a 7 nm polystyrene shell can effectively shield UiO-66 particles against 1 M H₂SO₄ and 1 M NaOH at elevated temperature, enabling their potential application in demanding chemical environments.

Transcellular delivery of messenger RNA payloads by a cationic supramolecular MOF platform

A supramolecular catiomer with a metal-organic framework (MOF) motif was developed to manufacture messenger RNA (mRNA) assemblies. In contrast to the linear catiomer, the dendritic MOF catiomer appeared to markedly improve the colloidal stability of the mRNA assemblies, particularly affording substantial protection to the mRNA payloads from enzymatic degradation, eventually conducing to appreciable mRNA transfection activities at the targeted cells.