Self-Assembly of Extracellular Vesicle-like Metal-Organic Framework Nanoparticles for Protection and Intracellular Delivery of Biofunctional Proteins

Materials for Immunotherapy

Breakthroughs in materials engineering have accelerated the progress of immunotherapy in preclinical studies. The interplay of chemistry and materials has resulted in improved loading, targeting, and release of immunomodulatory agents. An overview of the materials that are used to enable or improve the success of immunotherapies in preclinical studies is presented, from immunosuppressive to proinflammatory strategies, with particular emphasis on technologies poised for clinical translation. The materials are organized based on their characteristic length scale, whereby the enabling feature of each technology is organized by the structure of that material. For example, the mechanisms by which i) nanoscale materials can improve targeting and infiltration of immunomodulatory payloads into tissues and cells, ii) microscale materials can facilitate cell-mediated transport and serve as artificial antigen-presenting cells, and iii) macroscale materials can form the basis of artificial microenvironments to promote cell infiltration and reprogramming are discussed. As a step toward establishing a set of design rules for future immunotherapies, materials that intrinsically activate or suppress the immune system are reviewed. Finally, a brief outlook on the trajectory of these systems and how they may be improved to address unsolved challenges in cancer, infectious diseases, and autoimmunity is presented.

Bioinspired exosome-like therapeutics and delivery nanoplatforms

Exosomes have emerged as appealing candidate therapeutic agents and delivery nanoplatforms due to their endogenous features and unique biological properties. However, obstacles such as low isolation yield, considerable complexity and potential safety concerns, and inefficient drug payload substantially hamper their therapeutic applicability. To this end, developing bioinspired exosome-like nanoparticles has become a promising area to overcome certain limitations of their natural counterparts. Synthetically fabrication of exosome-like nanoparticles that harbor only crucial components of exosomes through controllable protocols strongly increases the pharmaceutical acceptability of these vesicles. Assembly of exosome-like nanovesicles derived from producer cells allows for a promising strategy for scale-up production. To improve the loading capability and delivery efficiency of exosomes, hybrid exosome-like nanovesicles and membrane-camouflaged nanoparticles towards better bridging synthetic nanocarriers with natural exosomes could be designed. Building off these observations, herein, efforts are made to give an overview of bioinspired exosome-like therapeutics and delivery nanoplatforms. We briefly recapitulate the recent advance in exosome biology with focus on tailoring exosomes as therapeutics and delivery vehicles. Furthermore, we elaborately discuss the biomimicry methodologies for preparation of exosome-like nanoparticles with special emphasis on offering insights into strategies for rational design of exosome-like biomaterials as effective and safe therapeutics and delivery nanoplatforms.

Nanobiohybrids: Materials approaches for bioaugmentation

Nanobiohybrids, synthesized by integrating functional nanomaterials with living systems, have emerged as an exciting branch of research at the interface of materials engineering and biological science. Nanobiohybrids use synthetic nanomaterials to impart organisms with emergent properties outside their scope of evolution. Consequently, they endow new or augmented properties that are either innate or exogenous, such as enhanced tolerance against stress, programmed metabolism and proliferation, artificial photosynthesis, or conductivity. Advances in new materials design and processing technologies made it possible to tailor the physicochemical properties of the nanomaterials coupled with the biological systems. To date, many different types of nanomaterials have been integrated with various biological systems from simple biomolecules to complex multicellular organisms. Here, we provide a critical overview of recent developments of nanobiohybrids that enable new or augmented biological functions that show promise in high-tech applications across many disciplines, including energy harvesting, biocatalysis, biosensing, medicine, and robotics.

A biomimetic MOF nanoreactor enables synergistic suppression of intracellular defense systems for augmented tumor ablation

A homotypic cancer cell membrane camouflaged MOF-based nanoreactor with the photothermal-starvation effect has been developed for synergistic suppression of intracellular defensive systems for enhanced cancer treatment.

Nanoscale metal-organic frameworks in detecting cancer biomarkers

Following the efficient performance of metal-organic frameworks (MOFs) as recognition elements in gas sensors, biosensors based on MOFs are now being investigated to capture and quantify potential cancer biomarkers, such as circulating tumor cells (CTCs), nucleic acids and proteins. The current status of MOF-based biosensors in the detection of early stages of cancer is in its infancy, although it has significantly emerged since the beginning of this decade. That said, salient research has been conducted in the past five years to utilize the distinctive porous crystalline structure of MOFs for highly sensitive and selective detection of cancer biomarkers. In this pursual, MOFs designed with bimetallic assembly, doped with magnetic nanoparticles, coated with polymers, and even conjugated with peptides or oligonucleotides have shown promising outcomes in detecting CTCs, nucleic acids and proteins. In particular, aptamer-conjugated MOFs are able to perform at a lower limit of detection down to the femtomolar, implying their efficacy for the point of care testing in clinical trials. In this way, aptasensors based on aptamer-conjugated MOFs present a newer sub-branch, to be coined as a MOFTA sensor in the current review. Considering the emerging progress and promising outcomes of MOFTA sensors as well as a variety of MOF-based techniques of detecting cancer biomarkers, this review will highlight their significant advances and related aspects in the recent five years on the context of detecting CTCs, nucleic acids and proteins for the early-stage detection of cancer.

Self-assembled single-atom nanozyme for enhanced photodynamic therapy treatment of tumor

Hypoxia of solid tumor compromises the therapeutic outcome of photodynamic therapy (PDT) that relies on localized O₂ molecules to produce highly cytotoxic singlet oxygen (¹O₂) species. Herein, we present a safe and versatile self-assembled PDT nanoagent, i.e., OxgeMCC-r single-atom enzyme (SAE), consisting of single-atom ruthenium as the active catalytic site anchored in a metal-organic framework Mn₃[Co(CN)₆]₂ with encapsulated chlorin e6 (Ce6), which serves as a catalase-like nanozyme for oxygen generation. Coordination-driven self-assembly of organic linkers and metal ions in the presence of a biocompatible polymer generates a nanoscale network that adaptively encapsulates Ce6. The resulted OxgeMCC-r SAE possesses well-defined morphology, uniform size distribution and high loading capacity. When conducting the in situ O₂ generation through the reaction between endogenous H₂O₂ and single-atom Ru species of OxgeMCC-r SAE, the hypoxia in tumor microenvironment is relieved. Our study demonstrates a promising self-assembled nanozyme with highly efficient single-atom catalytic sites for cancer treatment.

Modulating the Biofunctionality of Metal-Organic-Framework-Encapsulated Enzymes through Controllable Embedding Patterns

Embedding an enzyme within a MOF as exoskeleton (enzyme@MOF) offers new opportunities to improve the inherent fragile nature of the enzyme, but also to impart novel biofunctionality to the MOF. Despite the remarkable stability achieved for MOF-embedded enzymes, embedding patterns and conversion of the enzymatic biofunctionality after entrapment by a MOF have only received limited attention. Herein, we reveal how embedding patterns affect the bioactivity of an enzyme encapsulated in ZIF-8. The enzyme@MOF can maintain high activity when the encapsulation process is driven by rapid enzyme-triggered nucleation of ZIF-8. When the encapsulation is driven by slow coprecipitation and the enzymes are not involved in the nucleation of ZIF-8, enzyme@MOF tends to be inactive owing to unfolding and competing coordination caused by the ligand, 2-methyl imidazole. These two embedding patterns can easily be controlled by chemical modification of the amino acids of the enzymes, modulating their biofunctionality.

MOF nanoparticles with encapsulated dihydroartemisinin as a controlled drug delivery system for enhanced cancer therapy and mechanism analysis

Schematic illustration of (a) the preparation of DHA@ZIF-8 NPs and (b) their application for cancer therapy.

Boronic acid-engineered gold nanoparticles for cytosolic protein delivery

Boronic acid-engineered gold nanoparticles for effective cytosolic protein delivery with the help of hypertonicity.

Engineered Extracellular Vesicles as a Reliable Tool in Cancer Nanomedicine

Fast diagnosis and more efficient therapies for cancer surely represent one of the huge tasks for the worldwide researchers' and clinicians' community. In the last two decades, our understanding of the biology and molecular pathology of cancer mechanisms, coupled with the continuous development of the material science and technological compounds, have successfully improved nanomedicine applications in oncology. This review argues on nanomedicine application of engineered extracellular vesicles (EVs) in oncology. All the most innovative processes of EVs engineering are discussed together with the related degree of applicability for each one of them in cancer nanomedicines.

Recent developments on zinc(ii) metal-organic framework nanocarriers for physiological pH-responsive drug delivery

The high storage capacities and excellent biocompatibilities of zinc(ii) metal-organic frameworks (Zn-MOFs) have made them outstanding candidates as drug delivery carriers. Recent studies on the pH-responsive processes based on carrier-drug interactions have proven them to be the most efficient and effective way to control the release profiles of drugs. To satisfy the ever-growing demand in cancer therapy, great efforts are being devoted to the development of methods to precisely control drug release and achieve targeted use of an active substance at the right time and place. In this review article, we discuss the diverse stimuli based on Zn-MOFs carriers that have been achieved upon external activation from single pH-stimulus-responsive or/and multiple pH-stimuli-responsive viewpoints. Also, the perspectives and future challenges in this type of carrier system are discussed.

Carboxylated branched poly(β-amino ester) nanoparticles enable robust cytosolic protein delivery and CRISPR-Cas9 gene editing

Efficient cytosolic protein delivery is necessary to fully realize the potential of protein therapeutics. Current methods of protein delivery often suffer from low serum tolerance and limited in vivo efficacy. Here, we report the synthesis and validation of a previously unreported class of carboxylated branched poly(β-amino ester)s that can self-assemble into nanoparticles for efficient intracellular delivery of a variety of different proteins. In vitro, nanoparticles enabled rapid cellular uptake, efficient endosomal escape, and functional cytosolic protein release into cells in media containing 10% serum. Moreover, nanoparticles encapsulating CRISPR-Cas9 ribonucleoproteins (RNPs) induced robust levels of gene knock-in (4%) and gene knockout (>75%) in several cell types. A single intracranial administration of nanoparticles delivering a low RNP dose (3.5 pmol) induced robust gene editing in mice bearing engineered orthotopic murine glioma tumors. This self-assembled polymeric nanocarrier system enables a versatile protein delivery and gene editing platform for biological research and therapeutic applications.

Outer-Frame-Degradable Nanovehicles Featuring Near-Infrared Dual Luminescence for in Vivo Tracking of Protein Delivery in Cancer Therapy

In vivo monitoring of cargo protein delivery is critical for understanding the pharmacological efficacies and mechanisms during cancer therapy, but it still remains a formidable challenge because of the difficulty in observing nonfluorescent proteins at high resolution and sensitivity. Here we report an outer-frame-degradable nanovehicle featuring near-infrared (NIR) dual luminescence for real-time tracking of protein delivery in vivo. Upconversion nanoparticles (UCNPs) and fluorophore-doped degradable macroporous silica (DS) with spectral overlap were coupled to form a core-shell nanostructure as a therapeutic protein nanocarrier, which was eventually enveloped with a hyaluronic acid (HA) shell to prevent protein leakage and for recognizing tumor sites. The DS layer served as both a container to accommodate the therapeutic proteins and a filter to attenuate upconversion luminescence (UCL) of the inner UCNPs. After the nanovehicles selectively accumulated at tumor sites and entered cancer cells, intracellular hyaluronidase (HAase) digested the outermost HA protective shell and initiated the outer frame degradation-induced protein release and UCL restoration of UCNPs in the intracellular environment. Significantly, the biodistribution of the nanovehicles can be traced at the 710 nm NIR fluorescence channel of DS, whereas the protein release can be monitored at the 660 nm NIR fluorescence channel of UCNPs. Real-time tracking of protein delivery and release was achieved in vitro and in vivo by NIR fluorescence imaging. Moreover, in vitro and in vivo studies manifest that the protein cytochrome c-loaded nanovehicles exhibited excellent cancer therapeutic efficacy. This nanoplatform assembled by the outer-frame-degradable nanovehicles featuring NIR dual luminescence not only advances our understanding of where, when, and how therapeutic proteins take effect in vivo but also provides a universal route for visualizing the translocation of other bioactive macromolecules in cancer treatment and intervention.

Microfluidic Sonication To Assemble Exosome Membrane-Coated Nanoparticles for Immune Evasion-Mediated Targeting

Using natural membranes to coat nanoparticles (NPs) provides an efficient means to reduce the immune clearance of NPs and improve their tumor-specific targeting. However, fabrication of these drug-loaded biomimetic NPs, such as exosome membrane (EM)- or cancer cell membrane (CCM)-coated poly(lactic-co-glycolic acid) (PLGA) NPs, remains a challenging task owing to the heterogeneous nature of biomembranes and labor-intensive procedures. Herein, we report a microfluidic sonication approach to produce EM-, CCM-, and lipid-coated PLGA NPs encapsulated with imaging agents in a one-step and straightforward manner. Tumor cell-derived EM-coated PLGA NPs consisting of both endosomal and plasma membrane proteins show superior homotypic targeting as compared to CCM-PLGA NPs of similar sizes and core-shell structures in both in vitro and in vivo models. The underlying mechanism is associated with a significantly reduced uptake of EM-PLGA NPs by macrophages and peripheral blood monocytes, revealing an immune evasion-mediated targeting of EM-PLGA NPs to homologous tumors. Overall, this work illustrates the promise of using microfluidic sonication approach to fabricate biomimetic NPs for better biocompatibility and targeting efficacy.

Highly Stable and Long-Circulating Metal-Organic Frameworks Nanoprobes for Sensitive Tumor Detection In Vivo

High stability and extended circulation time in vivo are quite favorable for practical biomedical applications of nanomaterials, because they greatly facilitate the preferential tumor accumulation of nanomaterials, resulting in enhanced signal fidelity for imaging and improved therapeutic effect for treatment. Although many surface modification approaches have been employed to improve the stability and circulating behavior of nanomaterials, it still remains challenging in acquiring stable and long-lasting nanomaterials for in vivo bioimaging and therapy, especially for nanoscale metal-organic frameworks (NMOFs) due to their intrinsic instability in physiological conditions. Herein, a facile, one-step strategy is reported to encapsulate the zirconium (Zr)-based NMOF UiO-66 within 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) lipid bilayer (DOPA-LB). Contrary to UiO-66 NMOFs functionalized with polyethylene glycol, the obtained UiO-66@DOPA-LB presents significantly enhanced stability and impressive blood circulation time, allowing a higher accumulation of UiO-66@DOPA-LB in the tumor tissue. Benefited from these meritorious features, UiO-66@DOPA-LB labeled with near-infrared dye, IRDye 800CW, can not only achieve highly sensitive imaging of breast cancer tumor (5 mm), but also exhibits superior capability for early tumor (1-2 mm) detection. This study enriches the surface modification approach of NMOFs, and is of great importance for practical application of NMOFs in biomedical areas.

Redox-Responsive Polymeric Nanocomplex for Delivery of Cytotoxic Protein and Chemotherapeutics

Responsive delivery of anticancer proteins into cells is an emerging field in biological therapeutics. Currently, the delivery of proteins is highly compromised by multiple successive physiological barriers that reduce the therapeutic efficacy. Hence, there is a need to design a robust and sustainable nanocarrier to provide suitable protection of proteins and overcome the physiological barriers for better cellular accumulation. In this work, polyethylenimine (PEI) cross-linked by oxaliplatin(IV) prodrug (oxliPt(IV)) was used to fabricate a redox-responsive nanocomplex (PEI-oxliPt(IV)@RNBC/GOD) for the delivery of a reactive oxygen species-cleavable, reversibly caged RNase A protein (i.e., RNase A nitrophenylboronic conjugate, RNBC) and glucose oxidase (GOD) in order to realize efficient cancer treatment. The generation of hydrogen peroxide by GOD can uncage and restore the enzymatic activity of RNBC. On account of the responsiveness of the nanocomplex to highly reducing cellular environment, it would dissociate and release the protein and active oxaliplatin drug, causing cell death by both catalyzing RNA degradation and inhibiting DNA synthesis. As assessed by the RNA degradation assay, the activity of the encapsulated RNBC was recovered by the catalytic production of hydrogen peroxide from GOD and glucose substrate overexpressed in cancer cells. Monitoring of the changes in nanoparticle size confirmed that the nanocomplex could dissociate in the reducing environment, with the release of active oxaliplatin drug and protein. Confocal laser scanning microscopy (CLSM) and flow cytometry analysis revealed highly efficient accumulation of the nanocomplex as compared to free native proteins. In vitro cytotoxicity experiments using 4T1 cancer cells showed ∼80% cell killing efficacy, with highly efficient apoptosis induction. Assisted by the cationic polymeric carrier, it was evident from CLSM images that intracellular delivery of the therapeutic protein significantly depleted the RNA level. Thus, this work provides a promising platform for the delivery of therapeutic proteins and chemotherapeutic drugs for efficient cancer treatment.

The interaction of silica nanoparticles with catalase and human mesenchymal stem cells: biophysical, theoretical and cellular studies

Aim

Nanoparticles (NPs) have been receiving potential interests in protein delivery and cell therapy. As a matter of fact, NPs may be used as great candidates in promoting cell therapy by catalase (CAT) delivery into high oxidative stress tissues. However, for using NPs like SiO₂ as carriers, the interaction of NPs with proteins and mesenchymal stem cells (MSCs) should be explored in advance.

Methods

In the present study, the interaction of SiO₂ NPs with CAT and human MSCs (hMSCs) was explored by various spectroscopic methods (fluorescence, circular dichroism (CD), UV-visible), molecular docking and dynamics studies, and cellular (MTT, cellular morphology, cellular uptake, lactate dehydrogenase, ROS, caspase-3, flow cytometry) assays.

Results

Fluorescence study displayed that both dynamic and static quenching mechanisms and hydrophobic interactions are involved in the spontaneous interaction of SiO₂ NPs with CAT. CD spectra indicated that native structure of CAT remains stable after interaction with SiO₂ NPs. UV-visible study also revealed that the kinetic parameters of CAT such as Km, Vmax, Kcat, and enzyme efficiency were not changed after the addition of SiO₂ NPs. Molecular docking and dynamics studies showed that Si and SiO₂ clusters interact with hydrophobic residues of CAT and SiO₂ cluster causes minor changes in the CAT structure at a total simulation time of 200 ps. Cellular assays depicted that SiO₂ NPs induce significant cell mortality, change in cellular morphology, cellular internalization, ROS elevation, and apoptosis in hMSCs at higher concentration than 100 µg/mL (170 µM).

Conclusion

The current results suggest that low concentrations of SiO₂ NPs induce no substantial change or mortality against CAT and hMSCs, and potentially useful carriers in CAT delivery to hMSC.

Cell Membrane-Camouflaged NIR II Fluorescent Ag2 Te Quantum Dots-Based Nanobioprobes for Enhanced In Vivo Homotypic Tumor Imaging

The advantages of fluorescence bioimaging in the second near-infrared (NIR II, 1000-1700 nm) window are well known; however, current NIR II fluorescent probes for in vivo tumor imaging still have many shortcomings, such as low fluorescence efficiency, unstable performance under in vivo environments, and inefficient enrichment at tumor sites. In this study, Ag₂ Te quantum dots (QDs) that emit light at a wavelength of 1300 nm are assembled with poly(lactic-co-glycolic acid) and further encapsulated within cancer cell membranes to overcome the shortcomings mentioned above. The as-prepared ≈100 nm biomimetic nanobioprobes exhibit ultrabright (≈60 times greater than that of free Ag₂ Te QDs) and highly stable (≈97% maintenance after laser radiation for 1 h) fluorescence in the NIR II window. By combining the active homotypic tumor targeting capability derived from the source cell membrane with the passive enhanced permeation and retention effect, improved accumulation at tumor sites ((31 ± 2)% injection dose per gram of tumor) and a high tumor-to-normal tissue ratio (13.3 ± 0.7) are achieved. In summary, a new biomimetic NIR II fluorescent nanobioprobe with ultrabright and stable fluorescence, homotypic targeting and good biocompatibility for enhanced in vivo tumor imaging is developed in this study.

A boronic acid-rich dendrimer with robust and unprecedented efficiency for cytosolic protein delivery and CRISPR-Cas9 gene editing

Cytosolic protein delivery is of central importance for the development of protein-based biotechnologies and therapeutics; however, efficient intracellular delivery of native proteins remains a challenge. Here, we reported a boronic acid-rich dendrimer with unprecedented efficiency for cytosolic delivery of native proteins. The dendrimer could bind with both negatively and positively charged proteins and efficiently delivered 13 cargo proteins into the cytosol of living cells. All the delivered proteins kept their bioactivities after cytosolic delivery. The dendrimer ensures efficient intracellular delivery of Cas9 protein into various cell lines and showed high efficiency in CRISPR-Cas9 genome editing. The rationally designed boronic acid-rich dendrimer permits the development of an efficient platform with high generality for the delivery of native proteins.

Synergistic Amplification of Oxidative Stress-Mediated Antitumor Activity via Liposomal Dichloroacetic Acid and MOF-Fe2

Cancer cells are susceptible to oxidative stress; therefore, selective elevation of intracellular reactive oxygen species (ROS) is considered as an effective antitumor treatment. Here, a liposomal formulation of dichloroacetic acid (DCA) and metal-organic framework (MOF)-Fe²⁺ (MD@Lip) has been developed, which can efficiently stimulate ROS-mediated cancer cell apoptosis in vitro and in vivo. MD@Lip can not only improve aqueous solubility of octahedral MOF-Fe²⁺ , but also generate an acidic microenvironment to activate a MOF-Fe²⁺ -based Fenton reaction. Importantly, MD@Lip promotes DCA-mediated mitochondrial aerobic oxidation to increase intracellular hydrogen peroxide (H₂ O₂ ), which can be consequently converted to highly cytotoxic hydroxyl radicals (•OH) via MOF-Fe²⁺ , leading to amplification of cancer cell apoptosis. Particularly, MD@Lip can selectively accumulate in tumors, and efficiently inhibit tumor growth with minimal systemic adverse effects. Therefore, liposome-based combination therapy of DCA and MOF-Fe²⁺ provides a promising oxidative stress-associated antitumor strategy for the management of malignant tumors.

Metal-Organic Framework Nanoparticle-Based Biomineralization: A New Strategy toward Cancer Treatment

Cancer treatment using functional proteins, DNA/RNA, or complex bio-entities is important in both preclinical and clinical studies. With the help of nano-delivery systems, these biomacromolecules can enrich cancer tissues to match the clinical requirements. Biomineralization via a self-assembly process has been widely applied to provide biomacromolecules exoskeletal-like protection for immune shielding and preservation of bioactivity. Advanced metal-organic framework nanoparticles (MOFs) are excellent supporting matrices due to the low toxicity of polycarboxylic acids and metals, high encapsulation efficiency, and moderate synthetic conditions. In this review, we study MOFs-based biomineralization for cancer treatment and summarize the unique properties of MOF hybrids. We also evaluate the outlook of potential cancer treatment applications for MOFs-based biomineralization. This strategy likely opens new research orientations for cancer theranostics.

Harnessing Exosomes for the Development of Brain Drug Delivery Systems

Brain drug delivery is one of the most important bottlenecks in the development of drugs for the central nervous system. Cumulative evidence has emerged that extracellular vesicles (EVs) play a key role in intercellular communication. Exosomes, a subgroup of EVs, have received the most attention due to their capability in mediating the horizontal transfer of their bioactive inclusions to neighboring and distant cells, and thus specifically regulating the physiological and pathological functions of the recipient cells. This native and unique signaling mechanism confers exosomes with great potential to be developed into an effective, precise, and safe drug delivery system. Here, we provide an overview into the challenges of brain drug delivery and the function of exosomes in the brain under physiological and pathological conditions, and discuss how these natural vesicles could be harnessed for brain drug delivery and for the therapy of brain diseases.

Non-Viral Delivery To Enable Genome Editing

Genome-editing technologies such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENS), and the clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein system have revolutionized biological research. Each biotechnology consists of a DNA-binding protein that can be programmed to recognize and initiate double-strand breaks (DSBs) for site-specific gene modification. These technologies have the potential to be harnessed to cure diseases caused by aberrant gene expression. To be successful therapeutically, their functionality depends on their safe and efficient delivery into the cell nucleus. This review discusses the challenges in the delivery of genome-editing tools, and highlights recent innovations in non-viral delivery that have potential to overcome these limitations and advance the translation of genome editing towards patient care.

Nanoscale ATP-Responsive Zeolitic Imidazole Framework-90 as a General Platform for Cytosolic Protein Delivery and Genome Editing

Metal-organic frameworks (MOFs) are an emerging class of nanocarriers for drug delivery, owing to their tunable chemical functionality. Here we report ATP-responsive zeolitic imidazole framework-90 (ZIF-90) as a general platform for cytosolic protein delivery and CRISPR/Cas9 genome editing. The self-assembly of imidazole-2-carboxaldehyde and Zn²⁺ with protein forms ZIF-90/protein nanoparticles and efficiently encapsulates protein. It was found that, in the presence of ATP, the ZIF-90/protein nanoparticles are degraded to release protein due to the competitive coordination between ATP and the Zn²⁺ of ZIF-90. Intracellular delivery studies showed that the ZIF-90/protein nanoparticle can deliver a large variety of proteins into the cytosol, regardless of protein size and molecular weight. The delivery of cytotoxic RNase A efficiently prohibits tumor cell growth, while the effective delivery of genome-editing protein Cas9 knocks out the green fluorescent protein (GFP) expression of HeLa cells with efficiency up to 35%. Given the fact that ATP is upregulated in disease cells, it is envisaged that the ATP-responsive protein delivery will open up new opportunities for an advanced protein delivery and CRISPR/Cas9 genome editing for targeted disease treatment.

Emerging blood–brain-barrier-crossing nanotechnology for brain cancer theranostics

The advancements, perspectives, and challenges in blood–brain-barrier (BBB)-crossing nanotechnology for effective brain tumor delivery and highly efficient brain cancer theranostics.

High-yield expression in Escherichia coli, biophysical characterization, and biological evaluation of plant toxin gelonin

Gelonin is a plant toxin that exerts potent cytotoxic activity by inactivation of the 60S ribosomal subunit. The high-level expression of soluble gelonin still remains a great challenge and there was no detailed biophysical analysis of gelonin from Escherichia coli (E. coli) yet. In this study, the soluble and high-yield expression of recombinant gelonin (rGel) was achieved in E. coli BL21 (DE3) for the first time, with a yield of 6.03 mg/L medium. Circular dichroism (CD) analysis indicated that rGel consisted of 21.7% α-helix, 26.3% β-sheet, 18.5% β-turn, and 32.3% random coil, and it could maintain its secondary structure up to 60 °C. The antitumor activity of rGel was evaluated in two colon cancer cell lines-HCT116 and HCT-8, and it was clearly demonstrated that rGel exerted antiproliferative activity against these two cell lines by inhibiting cellular protein synthesis. These findings provide insights for researchers involved in the expression of similar biotoxins, and the biophysical characterizations of gelonin will favor its further therapeutic applications.

Size-Controlled Synthesis of Drug-Loaded Zeolitic Imidazolate Framework in Aqueous Solution and Size Effect on Their Cancer Theranostics in Vivo

Recently, metal-organic frameworks (MOFs) or coordination polymers have shown great potential for drug delivery, yet little has been done to study how particle size affects their tumor targeting and other in vivo features. This plight is probably due to two challenges: (1) the lack of a biocompatible method to precisely control the size of drug-loaded MOFs and (2) the lack of a robust and facile radiolabeling technique to trace particles in vivo. Here, we report a one-pot, rapid, and completely aqueous approach that can precisely tune the size of drug-loaded MOF at room temperature. A chelator-free ⁶⁴Cu-labeled method was developed by taking the advantage of this rapid and aqueous synthesis. Cancer cells were found to take drug-loaded MOFs in a size-dependent manner. The in vivo biodistribution of drug-loaded MOF was analyzed with positron emission tomography imaging, which, as far as we know, was used for the first time to quantitatively evaluate MOF in living animals, unveiling that 60 nm MOF showed longer blood circulation and over 50% higher tumor accumulation than 130 nm MOF. Altogether, this size-controlled method helps to find the optimal size of MOF as a drug carrier and opens new possibilities to construct multifunctional delivery systems for cancer theranostics.