Investigation of the interaction of thymine drugs with Be12O12 and Ca12O12 nanocages: A quantum chemical study

Based on the DFT in a Wb97xd/6-311+G* level of theory, the interaction of thymine derivatives with Be12O12 and Ca12O12 nanocages was investigated. It was found that adsorption energies of thymine molecules on the Be12/Ca12-O12 surface was around -43.16, -60.06 and -29.62, -50.71, -45.95, -30.27 kcal/mol, for thymine (TH1), 1-amino thymine (TH2) and thymine glycol (TH3), respectively and this result supported the drug's adsorption. Additionally, according to the FMOs and MEP studies, a charge transfer from TH's to nanocages. Additionally, both molecular orbitals demonstrate that the LUMO and HOMO are primarily found on the BeO's surface.

Maturation of the [FeFe]-Hydrogenase: Direct Transfer of the (κ3 -cysteinate)FeII (CN)(CO)2 Complex B from HydG to HydE

[FeFe]-hydrogenases efficiently catalyze the reversible oxidation of molecular hydrogen. Their prowess stems from the intricate H-cluster, combining a [Fe4 S4 ] center with a binuclear iron center ([2Fe]H ). In the latter, each iron atom is coordinated by a CO and CN ligand, connected by a CO and an azadithiolate ligand. The synthesis of this active site involves a unique multiprotein assembly, featuring radical SAM proteins HydG and HydE. HydG initiates the transformation of L-tyrosine into cyanide and carbon monoxide to generate complex B, which is subsequently transferred to HydE to continue the biosynthesis of the [2Fe]H -subcluster. Due to its instability, complex B isolation for structural or spectroscopic characterization has been elusive thus far. Nevertheless, the use of a biomimetic analogue of complex B allowed circumvention of the need for the HydG protein during in vitro functional investigations, implying a similar structure for complex B. Herein, we used the HydE protein as a nanocage to encapsulate and stabilize the complex B product generated by HydG. Using X-ray crystallography, we successfully determined its structure at 1.3 Å resolution. Furthermore, we demonstrated that complex B is directly transferred from HydG to HydE, thus not being released into the solution post-synthesis, highlighting a transient interaction between the two proteins.

Effector Regulated Catalytic Cyclization of Alkynoic Acids Using Pt2 L4 Cages

Metabolic pathways are highly regulated by effector molecules that influences the rate of enzymatic reactions. Inspired by the catalytic regulation found in living cells, we report a Pt₂ L₄ cage of which the activity can be controlled by effectors that bind inside the cage. The cage shows catalytic activity in the lactonization of alkynoic acids, with the reaction rates dependent on the effector guest bound in the cage. Some effector guests enhance the rate of the lactonization by up to 19-fold, whereas one decreases it by 5-fold. When mixtures of specific substrates are used, both starting materials and products act as guests for the Pt₂ L₄ cage, enhancing its catalytic activity for one substrate while reducing its activity for the other. The reported regulatory behavior obtained by the addition of effector molecules paves the way to the development of more complex, metabolic-like catalyst systems.

Metal-organic frameworks-derived In2O3/ZnO porous hollow nanocages for highly sensitive H2S gas sensor

The detection of hydrogen sulfide (H₂S) is critical because of its potential harm and widespread presence in the oil and gas sectors. The zeolitic imidazolate framework-8 (ZIF-8) derived ZnO nanostructures manufactured as gas sensors have exceptional sensitivity and selectivity for H₂S gas. In/Zn-ZIF-8 template material was synthesized by a simple one-step co-precipitation method followed by thermal annealing in air. The heat treatment resulted in In₂O₃/ZnO nanostructures with mixed heterostructures. The crystal structure (XRD), morphology (SEM/TEM), chemical state (XPS), surface area (BET), etc were investigated to ascertain the nature of the as-prepared material. SEM imagery revealed that the as-prepared In₂O₃/ZnO sensitive material had a microstructure of porous hollow nanocages with an average particle size of about 200 nm, which is beneficial to the diffusion and adsorption of gas molecules. The gas sensing performance test results of the In₂O₃/ZnO hollow nanocages show that their response to H₂S gas is significantly improved 67.5 @50 ppm H₂S (about 11 times that of pure ZnO nanocages) at an optimal temperature of 200 °C, better selectivity, lower theoretical detection limit and good linearity between gas concentration and response values. The enhanced gas sensing feat to H₂S gas is mainly attributed to the formation of n-n heterojunction and the wide surface area of the newly formed In₂O₃/ZnO porous hollow nanocages.

Modification and Production of Encapsulin

Encapsulins are a class of protein nanocages that are found in bacteria, which are easy to produce and engineer in E. coli expression systems. The encapsulin from Thermotoga maritima (Tm) is well studied, its structure is available, and without modification it is barely taken up by cells, making it promising candidates for targeted drug delivery. In recent years, encapsulins are engineered and studied for potential use as drug delivery carriers, imaging agents, and as nanoreactors. Consequently, it is important to be able to modify the surface of these encapsulins, for example, by inserting a peptide sequence for targeting or other functions. Ideally, this is combined with high production yields and straightforward purification methods. In this chapter, we describe a method to genetically modify the surface of Tm and Brevibacterium linens (Bl) encapsulins, as model systems, to purify them and characterize the obtain nanocages.

Theoretical study of glycoluril by highly symmetrical magnesium oxide Mg12O12 nanostructure: adsorption, detection, SERS enhancement, and electrical conductivity study

Using metal substrates that are nanoscale in size, surface-enhanced Raman scattering (SERS) is a technique for enhancing the Raman signal of biomolecules. Numerous industries including sensing materials, adsorption and medical devices, use nanomaterials like nanocages and nanoclusters. To discover a possible novel sensor platform involving a small metal cluster and a curved rigid substrate, we used density functional theoretical (DFT) simulations to explore the adsorption of glycoluril (GLC), a prospective drug intermediate, on a pure magnesium oxide cage (Mg₁₂O₁₂). This well defined cage was used as (i) an exact probable structure that could be used as well as (ii) a general model for MgO nanostructures. We also investigated the mono Al-doped Mg₁₂O₁₂ nanocage version Mg₁₁AlO₁₂. All computations were performed at the M06-2X level of theory. The GLC binds to the Mg₁₂O₁₂ nanocage by way of strong donor-acceptor interactions. The adsorption is releasing - 45.80 kcal mol^-1 of energy. Due to Al doping, the energy gap of GLC-Mg₁₁AlO₁₂ (1.91 eV) is reduced from that of GLC-Mg₁₂O₁₂ (4.28 eV) and hence there is an increase in electrical conductivity of GLC-Mg₁₁AlO₁₂. The electronic change in the nanocage's conductivity can be transformed into an electrical signal which can be used to detect the presence of the drug analyte. In addition, when a GLC molecule is present, the work function of the nanocage is also reduced. The MgO nanocage, we conclude, is a work function type as well as a possible electronic sensor for GLC drug detection. GLC desorption from the Mg₁₁AlO₁₂ surface recovers more quickly in comparison with Mg₁₂O₁₂ recovery time. The AIM and NCIs assessed in this study were performed to help analyze the electronic structures of the complexes. Our findings pave the possibility for Mg₁₁AlO₁₂ nanostructures to be used in drug recognition.

Electronic sensors for alkali and alkaline earth cations based on Fullerene-C60 and silicon doped on C60 nanocages: a computational study

In this research, we have reported the electrical sensitivity of pristine C60 and silicon doped on C60 (SiC59) nanocages as sensors that can be used for detecting the presence of alkali (Li⁺, Na⁺, K⁺) and alkaline earth (Be²⁺, Mg²⁺, Ca²⁺) cations. The computations are carried out at the B3LYP level of theory with a 6-31G(d) basis set. The atoms in molecules (AIM) and natural bond orbital (NBO) analyses are performed to evaluate the intermolecular interactions between cations and nanocages. The physical properties of the selected complexes are also analyzed by the frontier molecular orbital, energy gap, electronegativity, chemical hardness, softness, and other quantities such as work function, number of transferred electron, and dipole moment. The results show that the adsorption process is exothermic and with increasing the charge of cations, the adsorption energies enhance. Our findings also reveal a decrease in the energy gap along with an increase in the electrical conductivity of the respective complexes. Finally, the density of state calculations is presented to confirm the obtained results.

Construction of Single-Crystalline Hierarchical ZSM-5 with Open Nanoarchitectures via Anisotropic-Kinetics Transformation for the Methanol-to-Hydrocarbons Reaction

We report an anisotropic-kinetics transformation strategy to prepare single-crystalline aluminosilicate MFI zeolites (ZSM-5) with highly open nanoarchitectures and hierarchical porosities. The methodology relies on the cooperative effect of in situ etching and recrystallization on the evolution of pure-silica MFI zeolite (silicalite-1) nanotemplates under hydrothermal conditions. The strategy enables a controllable preparation of ZSM-5 nanostructures with diverse open geometries by tuning the relative rate difference between etching and recrystallization processes. Meanwhile, it can also be extended to synthesize other heteroatom-substituted MFI zeolite nanocages. Compared with conventional ZSM-5 microcrystals, nanocrystals, and nanoboxes, the ZSM-5 nanocages with single-crystalline nature, highly open nanoarchitectures, and hierarchical porosities exhibit remarkably enhanced catalytic lifetime and low coking rate in the methanol-to-hydrocarbons (MTH) reaction.

N-Doped Carbon Electrocatalyst: Marked ORR Activity in Acidic Media without the Contribution from Metal Sites?

Fe-N-C electrocatalysts have been demonstrated to be the most promising substitutes for benchmark Pt/C catalysts for the oxygen reduction reaction (ORR). Herein, we report that N-doped carbon materials with trace amounts of iron (0-0.08 wt. %) show excellent ORR activity and durability comparable and even superior to those of Pt/C in both alkaline and acidic media without significant contribution by the metal sites. Such an N-doped carbon (denoted as N-HPCs) features a hollow and hierarchically porous architecture, and more importantly, a noncovalently bonded N-deficient/N-rich heterostructure providing the active sites for oxygen adsorption and activation owing to the efficient electron transfer between the layers. The primary Zn-air battery using N-HPCs as the cathode delivers a much higher power density of 158 mW cm^-2 , and the maximum power density in the H₂ -O₂ fuel cell reaches 486 mW cm^-2 , which is comparable to and even better than those using conventional Fe-N-C catalysts at cathodes.

DFT analysis of valproic acid adsorption onto Al12/B12-N12/P12 nanocages with solvent effects

Using density functional theory, the adsorption of valproic acid onto the surface of fullerene-like nanocages was investigated. Valproic acid interacts with the nanocages through the carboxylic group with energies of - 144.14, - 109.71, - 105.22, and - 84.96 kcal/mol. The frontier molecular orbital (FMO) energy levels were considerably altered upon adsorption, resulting in a reduction in energy gap and increase in electrical conductivity. This suggests that nanocages could be used as sensors as well as options for drug administration in biological systems. Solvation effects in water are also reported.

Novel zinc-silver nanocages for drug delivery and wound healing: Preparation, characterization and antimicrobial activities

Metal organic framework (MOF)-nanocages (MOF-NCs) in the form of zinc-based nanoparticles (NPs) were synthesized as drug carriers for the purpose of wound healing. The prepared NCs (single and bi-metallic with silver-MOF) were based on zinc and they were loaded with ascorbic acid (vitamin C) as a model drug which accelerates wound healing. The NCs were then investigated by several characterization techniques such as XRD, TEM, FTIR and BET surface area. Furthermore, the release behavior of the loaded ascorbic acid from the developed NCs was measured in phosphate buffer solution (PBS). NCs antibacterial activity was tested against strain of gram-positive bacteria (Staphylococcus aureus ATCC- 29213, Streptococcus pyogenes ATCC-19615 and Bacillus subtilis ATCC-6633), gram-negative bacteria strain (Pseudomonas aeruginosaATCC-27853and Escherichia coli ATCC-25922) and fungi (Candida albicans ATCC-10231).The physicochemical features of the NCs were confirmed by the results obtained from XRD and FTIR measurements. The particle size of the NCs was confirmed to be in the range of 30-50 nm. Prolonged drug release that was combined with impressive antibacterial activities, and good wound healing rates were also recognized for the zinc based NCs in comparison to commonly used Ag NPs. It is concluded that the current NCs are potentially suitable for wound healing and drug delivery applications.

Adsorption of adipic acid in Al/B-N/P nanocages: DFT investigations

Drug delivery clusters based on nanocages recently have been the most capable to study. Adipic acid (ADPA) interaction mechanism over nanocages of X(Al/B)12Y(N/P)12 was investigated. We analyzed various electronic, chemical, and spectroscopic properties with nanocages of the adsorbed ADPA molecule. Adsorption energies were calculated to study the adsorption of ADPA with nanocages. Raman enhanced surface scattering is used to track the drug as an effective approach to vibrational spectroscopy. Detection of the drug has been investigated using the SERS properties of nanocages. Title drug acts as a donor of electrons and adsorbs at the electrophilic site of nanocages. Variations in chemical descriptors to recognize the sensing property of ADPA-nanocages are also noted. Analysis of various properties explains enhancement which makes it possible to detect the drug in other products. • Interaction of adipic acid with fullerene-like metal nanocages • Enhancement of spectral properties • Changes in charge transfer values in nanocage-drug system • Docking studies identify the drug delivery property.

3D Taraxacum-like porous Pd nanocages with Bi doping: High-performance non-Pt electrocatalysts for ethanol oxidation reaction

Modifying the electronic structure and optimizing the geometric structure can expeditiously tune the electrocatalytic properties of catalysts, resulting in considerably enhanced electrocatalytic performance towards electrocatalytic oxidation of liquid fuels. We herein report a simple synthetic strategy to prepare Bi-doped 3D taraxacum-like Pd nanocages (NCs) composed of porous nanosheets, which possess high surface areas and strong synergistic effects. Notably, a trace of Bi diffuses into the lattice of Pd and increases the electronic effects of the surface of Pd, endowing PdBi-0.5 NCs/C with superior electrocatalytic performance towards ethanol oxidation reaction (EOR). The mass activity and specific activity of PdBi-0.5 NCs/C were 3494.8 mA mg_Pd^-1 and 10.37 mA cm^-2, being 4.08- and 4.82- fold enhancements as compared with commercial Pd/C, respectively. Moreover, the highly open porous 3D nanocages structure with rich active sites and defects can also facilitate the mass/electron transfer to favor the EOR kinetics.

3D Carbon Frameworks for Ultrafast Charge/Discharge Rate Supercapacitors with High Energy-Power Density

Carbon-based electric double layer capacitors (EDLCs) hold tremendous potentials due to their high-power performance and excellent cycle stability. However, the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte. Herein, 3D carbon frameworks (3DCFs) constructed by interconnected nanocages (10-20 nm) with an ultrathin wall of ca. 2 nm have been fabricated, which possess high specific surface area, hierarchical porosity and good conductive network. After deoxidization, the deoxidized 3DCF (3DCF-DO) exhibits a record low IR drop of 0.064 V at 100 A g^-1 and ultrafast charge/discharge rate up to 10 V s^-1. The related device can be charged up to 77.4% of its maximum capacitance in 0.65 s at 100 A g^-1 in 6 M KOH. It has been found that the 3DCF-DO has a great affinity to EMIMBF₄, resulting in a high specific capacitance of 174 F g^-1 at 1 A g^-1, and a high energy density of 34 Wh kg^-1 at an ultrahigh power density of 150 kW kg^-1 at 4 V after a fast charge in 1.11 s. This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density.

Vault packaged enzyme mediated degradation of amino-aromatic energetic compounds

Amino-aromatic compounds, 2-amino-4-nitrotoluene (ANT), and 2,4-diaminotoluene (DAT) are carcinogens and environmentally persistent pollutants. In this study, we investigated their degradation by natural manganese peroxidase (nMnP) derived from Phanerochaete chrysosporium and recombinant manganese peroxidase packaged in vaults (vMnP). Encapsulation of manganese peroxidase (MnP) in ribonucleoprotein nanoparticle cages, called vaults, was achieved by creating recombinant vaults in yeast Pichia pastoris. Vault packaging increased the stability of MnP by locally sequestering multiple copies of the enzyme. Within 96  h, both vMnP and nMnP catalyzed over 72% removal of ANT in-vitro, which indicates that vault packaging did not limit substrate diffusion. It was observed that vMnP was more efficient than nMnP and P. chrysosporium for the catalysis of target contaminants. Only 57% of ANT was degraded by P. chrysosporium even when MnP activity reached about 480 U L^-1 in cultures. At 1.5 U L^-1 initial activity, vMnP achieved 38% of ANT and 51% of DAT degradation, whereas even 2.7 times higher activity of nMnP showed insignificant biodegradation of both compounds. These results imply that due to protection by vault cages, vMnP has lower inactivation rates. Thus, it works effectively at lower dosage for a longer duration compared to nMnP without requiring frequent replenishment. Collectively, these results indicate that fungal enzymes packaged in vault nanoparticles are more stable and active, and they would be effective in biodegradation of energetic compounds in industrial processes, waste treatment, and contaminated environments.

Synthesis of Cubic Ni(OH)2 Nanocages Through Coordinating Etching and Precipitating Route for High-Performance Supercapacitors

Rational design of cage-like structure is an effective method for the improvement of the capacitive performance of transition metal hydroxides. In this work, cubic Ni(OH)2 nanocages (Ni(OH)2 NCs) were constructed through a coordinating etching and precipitating (CEP) route. Ni(OH)2 NCs possess abundant active sites, sufficient diffusion channels, and accelerated electron transfer rate, which are beneficial for electrochemical kinetics. As a positive electrode for supercapacitors, the Ni(OH)2 NCs/Ni foam (NF) electrode presents a high specific capacitance of 539.8 F g^-1 at 1 A g^-1, which is much larger than that of broken Ni(OH)2 NCs/NF (Ni(OH)2 BNCs/NF, 87.3 F g^-1 at 1 A g^-1). In addition, the Ni(OH)2 NCs/NF electrode still retains 96.9% of its initial specific capacitance after 2000 cycles. The asymmetric supercapacitor (ASC) devices were assembled using Ni(OH)2 NCs/NF and activated carbon (AC)/NF as positive and negative electrodes, respectively. The ASC exhibits a higher energy density of 23.3 Wh kg^-1 at a power density of 800 W kg^-1 compared to Ni(OH)2 BNCs/NF (3 Wh kg^-1 at 880 W kg^-1). These results demonstrate that the Ni(OH)2 NCs/NF electrode presents potential applications in the field of energy storage. The design of cage-like structure paves an effective way to achieve high-performance electrode materials.

Uric acid supported one-pot solvothermal fabrication of rhombic-like Pt35Cu65 hollow nanocages for highly efficient and stable electrocatalysis

High activity and good durability of electrocatalysts are of significance in practical applications of fuel cells. Among them, multi-component metallic hollow nanocages/nanoframes show great potential as advanced catalysts because of their highly open structures, large surface area and good stability. Herein, we report a general uric acid-mediated solvothermal method for shape-controlled synthesis of rhombic-like Pt₃₅Cu₆₅ hollow nanocages (HNCs) with uric acid as co-reductant and co-structure-directing agent. Uric acid and cetyltrimethylammonium chloride (CTAC) played important roles in the hollow cages. The specific architectures showed remarkably enhanced catalytic properties towards glycerol oxidation reaction (GOR), ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) with the enhanced specific activity, outperforming commercial Pt/C (20 wt%). This work provides a new avenue for rational design of novel bimetallic nanocatalysts with enhanced characters in energy storage and conversion.

Apoferritin nanocages loading mertansine enable effective eradiation of cancer stem-like cells in vitro

Cancer stem-like cells (CSCs) are proposed to be responsible for tumor metastasis, resistance and relapse after therapy, but are unable to be eliminated by many current therapies. Herein, we report that the apoferritin nanocages loading cytotoxic mertansine (M-AFN) can significantly improve their uptake in CSCs-enriched tumorspheres and effectively eradicate CSCs in tumorspheres for anticancer therapy. M-AFN were uniformly nanocage structures with the mean diameter of 11.26 ± 2.58 nm and the loading capacity of 0.62%. In the CSCs-enriched tumorsphere model, M-AFN could be preferentially internalized by tumorsphere cells and the average half-inhibitory concentration (IC₅₀) of M-AFN was obviously reduced by 5.46-fold when comparing to the parent 4T1 breast cancer cells. Moreover, both the already existing tumorspheres and the formation of secondary tumorspheres were drastically disrupted by M-AFN, but barely impacted by mertansine alone. The flow cytometer analysis showed the CSCs fractions in tumorspheres were considerably reduced by the M-AFN treatment. Therefore, the apoferritin nanocages represent an encouraging nanoplatform to eradicate CSCs for effective anticancer therapy.

Designed trimer-mimetic TNF superfamily ligands on self-assembling nanocages

Presentation of an endogenous bioactive ligand in its native form is a key factor in controlling and determining its bioactivity, stability, and therapeutic efficacy. In this study, we developed a novel strategy for presenting trimeric ligands on nanocages by designing, optimizing and testing based on the rational design, high-resolution structural analysis and agonistic activity assays in vitro and in vivo. We successfully designed a nanocage that presents the TNF superfamily member, TRAIL (TNF-related apoptosis-inducing ligand) in its native-like trimeric structure. The native structure of TRAIL complexes was mimicked on the resulting trimeric TRAIL-presenting nanocages (TTPNs) by inserting sufficient spacing, determined from three-dimensional structural models, to provide optimal access to the corresponding receptors. The efficacy of TTPNs as an anti-tumor agent was confirmed in preclinical studies, which revealed up to 330-fold increased affinity, 62.5-fold enhanced apoptotic activity, and improved pharmacokinetic characteristics and stability compared with the monomeric form of TRAIL (mTRAIL). In this latter context, TTPNs exhibited greater than 90% stability over 1 mo, whereas ∼50% of mTRAIL aggregated within 2 d. Consistent with their enhanced stability and ultra-high affinity for the TRAIL receptor, TTPNs effectively induced apoptosis of tumor cells in vivo, leading to effective inhibition of tumor growth. Although TRAIL was used here as a proof-of-concept, all members of the TNF superfamily share the TNF homology domain (THD) and have similar distances between ecto-domain C-termini. Thus, other TNF superfamily ligands could be genetically substituted for the TRAIL ligand on the surface of this biomimetic delivery platform.

Encapsulation of Exogenous Proteins in Vault Nanoparticles

Natural vault nanoparticles are ribonucleoprotein particles with a mass of 13 MDa that have been found in a wide variety of eukaryotes. Empty recombinant vaults are assembled from heterologously expressed Major Vault Protein (MVP), forming the barrel-shaped vault shell. These structures are morphologically indistinguishable from natural vault particles. Here, we describe the packaging and purification of exogenous proteins into these recombinant vault particles by mixing with proteins attached to the INT domain that binds to MVP.