Coordination-based self-assembled capsules (SACs) for protein, CRISPR-Cas9, DNA and RNA delivery

Steric and Geometrical Frustration Generate Two Higher-Order CuI12L8 Assemblies from a Triaminotriptycene Subcomponent

The use of copper(I) in metal-organic assemblies leads readily to the formation of simple grids and helicates, whereas higher-order structures require complex ligand designs. Here, we report the clean and selective syntheses of two complex and structurally distinct CuI12L8 frameworks, 1 and 2, which assemble from the same simple triaminotriptycene subcomponent and a formylpyridine around the CuI templates. Both represent new structure types. In T-symmetric 1, the copper(I) centers describe a pair of octahedra with a common center but whose vertices are offset from each other, whereas in D3-symmetric 2, the metal ions form a distorted hexagonal prism. The syntheses of these architectures illustrate how more intricate CuI-based complexes can be prepared via subcomponent self-assembly than has been possible to date through consideration of the interplay between the subcomponent geometry and solvent and electronic effects.

Stereocontrolled Self-Assembly of a Helicate-Bridged CuI12L4 Cage That Emits Circularly Polarized Light

Control over the stereochemistry of metal-organic cages can give rise to useful functions that are entwined with chirality, such as stereoselective guest binding and chiroptical applications. Here, we report a chiral CuI12L4 pseudo-octahedral cage that self-assembled from condensation of triaminotriptycene, aminoquinaldine, and diformylpyridine subcomponents around CuI templates. The corners of this cage consist of six head-to-tail dicopper(I) helicates whose helical chirality can be controlled by the addition of enantiopure 1,1'-bi-2-naphthol (BINOL) during the assembly process. Chiroptical and nuclear magnetic resonance (NMR) studies elucidated the process and mechanism of stereochemical information transfer from BINOL to the cage during the assembly process. Initially formed CuI(BINOL)2 thus underwent stereoselective ligand exchange during the formation of the chiral helicate corners of the cage, which determined the overall cage stereochemistry. The resulting dicopper(I) helicate corners of the cage were also shown to generate circularly polarized luminescence.

Hierarchical mesoporous NanoMUV-2 for the selective delivery of macromolecular drugs

Although Metal-organic frameworks (MOFs) have received attention as drug delivery systems, their application in the delivery of macromolecules is limited by their pore size and opening. Herein, we present the synthesis of nanostructured MUV-2, a hierarchical mesoporous iron-based MOF that can store high payloads of the macromolecular drug paclitaxel (ca. 23% w/w), increasing its selectivity towards HeLa cancer cells over HEK non-cancerous cells. Moreover, this NanoMUV-2 permits full degradation under simulated physiological conditions while maintaining biocompatibility, and is amenable to specific surface modifications that increase its cell permeation, efficient cytosol delivery and cancer-targeting effect, further intensifying the cancer selectivity of paclitaxel.

Hetero-Diels-Alder Reaction between Singlet Oxygen and Anthracene Drives Integrative Cage Self-Sorting

A ZnII8L6 pseudocube containing anthracene-centered ligands, a ZnII4L'4 tetrahedron with a similar side length as the cube, and a trigonal prism ZnII6L3L'2 were formed in equilibrium from a common set of subcomponents. Hetero-Diels-Alder reaction with photogenerated singlet oxygen transformed the anthracene-containing "L" ligands into endoperoxide "LO" ones and ultimately drove the integrative self-sorting to form the trigonal prismatic cage ZnII6LO3L'2 exclusively. This ZnII6LO3L'2 structure lost dioxygen in a retro-Diels-Alder reaction after heating, which resulted in reversion to the initial ZnII8L6 + ZnII4L'4 ⇌ 2 × ZnII6L3L'2 equilibrating system. Whereas the ZnII8L6 pseudocube had a cavity too small for guest encapsulation, the ZnII6L3L'2 and ZnII6LO3L'2 trigonal prisms possessed peanut-shaped internal cavities with two isolated compartments divided by bulky anthracene panels. Guest binding was also observed to drive the equilibrating system toward exclusive formation of the ZnII6L3L'2 structure, even in the absence of reaction with singlet oxygen.

Amino Acid-Coated Zeolitic Imidazolate Framework for Delivery of Genetic Material in Prostate Cancer Cell

Metal-organic frameworks (MOFs) are currently under progressive development as a tool for non-viral biomolecule delivery. Biomolecules such as proteins, lipids, carbohydrates, and nucleic acids can be encapsulated in MOFs for therapeutic purposes. The favorable physicochemical properties of MOFs make them an attractive choice for delivering a wide range of biomolecules including nucleic acids. Herein, a green fluorescence protein (GFP)-expressing plasmid DNA (pDNA) is used as a representative of a biomolecule to encapsulate within a Zn-based metal-organic framework (MOF) called a zeolitic imidazolate framework (ZIF). The synthesized biocomposites are coated with positively charged amino acids (AA) to understand the effect of surface functionalization on the delivery of pDNA to prostate cancer (PC-3) cells. FTIR and zeta potential confirm the successful preparation of positively charged amino acid-functionalized derivatives of pDNA@ZIF (i.e., pDNA@ZIF_AA). Moreover, XRD and SEM data show that the functionalized derivates retain the pristine crystallinity and morphology of pDNA@ZIF. The coated biocomposites provide enhanced uptake of genetic material by PC-3 human prostate cancer cells. The AA-modulated fine-tuning of the surface charge of biocomposites results in better interaction with the cell membrane and enhances cellular uptake. These results suggest that pDNA@ZIF_AA can be a promising alternative tool for non-viral gene delivery.

Dynamic Hydrogen-Bonded Zinc Adeninate Framework (ZAF) for Immobilization of Catalytic DNA

Effective immobilization and delivery of genetic materials is at the forefront of biological and medical research directed toward tackling scientific challenges such as gene therapy and cancer treatment. Herein we present a biologically inspired hydrogen-bonded zinc adeninate framework (ZAF) consisting of zinc adeninate macrocycles that self-assemble into a 3D framework through adenine-adenine interactions. ZAF can efficiently immobilize DNAzyme with full protection against enzyme degradation and physiological conditions until it is successfully delivered into the nucleus. As compared to zeolitic imidazolate frameworks (ZIFs), ZAFs are twofold more biocompatible with a significant loading efficiency of 96 %. Overall, our design paves the way for expanding functional hydrogen-bonding-based systems as potential platforms for the loading and delivery of biologics.

Cytotoxicity and mechanism of action of metal complexes: An overview

After the discovery of cisplatin, many metal compounds were investigated for the therapy of diseases, especially cancer. The high therapeutic potential of metal-based compounds is related to the special properties of these compounds, such as their redox activity and ability to target vital biological sites. The overproduction of ROS and the consequent destruction of the membrane potential of mitochondria and/or the DNA helix is one of the known pathways leading to the induction of apoptosis by metal complexes. The apoptosis process can occur via the death receptor pathway and/or the mitochondrial pathway. The expression of Bcl2 proteins and the caspase family play critical roles in these pathways. In addition to apoptosis, autophagy is another process that regulates the suppression or promotion of various cancers through a dual action. On the other hand, the ability to interact with DNA is an important property found in several metal complexes with potent antiproliferative effects against cancer cells. These interactions were classified into two important categories: covalent/coordinated or subtle, and non-coordinated interactions. The anticancer activity of metal complexes is sometimes achieved by the simultaneous combination of several mechanisms. In this review, the anticancer effect of metal complexes is mechanistically discussed by different pathways, and some effective agents on their antiproliferative properties are explained.

Multiscale Modeling Unravels the Influence of Biomembranes on the Photochemical Properties of Embedded Anti-Oxidative Polyphenolic and Phenanthroline Chelating Dyes

The embedding of caffeate methyl ester, the flavonoids luteolin and quercetin, and the o-phenanthroline and neocuproine in a liquid disordered lipid bilayer has been studied through extensive atomistic calculations. The location and the orientation of these bio-active antioxidants are explained and analyzed. While the two phenanthrolines strongly associate with the lipid tail region, the other three compounds are rather found among the head groups. The simulations showcase conformational changes of the flavonoids. Through the use of a hybrid quantum mechanics-molecular mechanics scheme and supported by a profound benchmarking of the electronic excited-state method for these compounds, the influence of the anisotropic environment on the compounds' optical properties is analyzed. Influences of surrounding water molecules and of the polar parts of the lipids on the transition dipole moments and excited-state dipole moments are weighted with respect to a change in conformation. The current study highlights the importance of the mapping of molecular interactions in model membranes and pinpoints properties, which can be biomedically used to discriminate and detect different lipid environments.

Improving Stability and Specificity of CRISPR/Cas9 System by Selective Modification of Guide RNAs with 2'-fluoro and Locked Nucleic Acid Nucleotides

The genome editing approach using the components of the CRISPR/Cas system has found wide application in molecular biology, fundamental medicine and genetic engineering. A promising method is to increase the efficacy and specificity of CRISPR/Cas-based genome editing systems by modifying their components. Here, we designed and chemically synthesized guide RNAs (crRNA, tracrRNA and sgRNA) containing modified nucleotides (2'-O-methyl, 2'-fluoro, LNA-locked nucleic acid) or deoxyribonucleotides in certain positions. We compared their resistance to nuclease digestion and examined the DNA cleavage efficacy of the CRISPR/Cas9 system guided by these modified guide RNAs. The replacement of ribonucleotides with 2'-fluoro modified or LNA nucleotides increased the lifetime of the crRNAs, while other types of modification did not change their nuclease resistance. Modification of crRNA or tracrRNA preserved the efficacy of the CRISPR/Cas9 system. Otherwise, the CRISPR/Cas9 systems with modified sgRNA showed a remarkable loss of DNA cleavage efficacy. The kinetic constant of DNA cleavage was higher for the system with 2'-fluoro modified crRNA. The 2'-modification of crRNA also decreased the off-target effect upon in vitro dsDNA cleavage.

Metal Complexes in Target-Specific Anticancer Therapy: Recent Trends and Challenges

Cancer is characterized by abnormal cell differentiation in or on the part of the body. The most commonly used chemotherapeutic drugs are developed to target rapidly dividing cells, such as cancer cells, but they also damage healthy epithelial cells. This has serious consequences for normal cells and become responsible for the development of various disorders. Several strategies for delivering the cytotoxic drugs to cancerous sites that limit systemic toxicity and other adverse effects have recently been evolved. Among them, biomolecule-conjugated metal complexes-based cancer targeting strategies have shown tremendous advantages in cancer therapy. This review focuses on several chemoselective biomolecules-bound metal complexes as prospective cancer therapy-targeted agents. In this review, we presented the details of the various extra- and intracellular targeting mechanisms in cancer therapy. We also addressed the current clinical issues and recent therapeutic strategies in targeted cancer therapy that may pave a way for the future direction of metal complexes-based targeted cancer therapy.

Influence of the Synthesis and Storage Conditions on the Activity of Candida antarctica Lipase B ZIF-8 Biocomposites

The biomimetic mineralization of zeolitic imidazolate framework-8 (ZIF-8) has been reported as a strategy for enzyme immobilization, enabling the heterogenization and protection of biomacromolecules. Here, we report the preparation of different Candida antarctica lipase B biocomposites (CALB@ZIF-8) formed by altering the concentrations of Zn2+ and 2-methylimidazole (2-mIM). The influence of synthetic conditions on the catalytic activity of the lipase CALB was examined by hydrolysis and transesterification assays in aqueous and organic media, respectively. We demonstrated that for both reactions, activity was retained for the biocomposites formed at low Zn2+/2-mIM ratios but notably almost entirely lost when the ligand concentration used to form the biocomposites was increased. Additionally, phosphate buffer could regenerate the activity of larger particles by degrading the crystal surfaces and releasing encapsulated CALB into solution. Transesterification reactions using CALB@ZIF-8 biocomposites were undertaken in 100% hexane, giving rise to enhanced CALB activity relative to the free enzyme. These observations highlight the fundamental importance of synthetic protocols and operating parameters for developing enzyme@MOF biocomposites with improved activity in challenging conditions.

Photoactivatable nanoCRISPR/Cas9 System Based on crRNA Reversibly Immobilized on Carbon Nanoparticles

Here, we proposed a new approach to engineering a photoactivatable CRISPR/Cas9 gene-editing system. The novel nanoCRISPR/Cas9 system is based on the use of auxiliary photocleavable oligodeoxyribonucleotides (PC-DNAs) complementary to crRNA. PC-DNAs contained up to three UV-sensitive linkers made of 1-(2-nitrophenyl)-1,2-ethanediol inside the oligonucleotide chain. Immobilizing PC-DNAs on the surface of carbon nanoparticles through 3′-terminal pyrene residue provided sufficient blocking of crRNA (and corresponding Cas9 activity) before UV irradiation and allows for crRNA release after UV irradiation at 365 nm, which restores Cas9 activity. We optimized the length of blocking photocleavable oligonucleotide, number of linkers, time of irradiation, and the type of carbon nanoparticles. Based on the results, we consider the nanoCRISPR/Cas9 system involving carbon-encapsulated iron nanoparticles the most promising. It provides the greatest difference of functional activity before/after irradiation and can be used in prospective for magnetic field-controlled delivery of CRISPR system into the target cells or tissues and spatiotemporal gene editing induced by UV irradiation.