Accessible Surface Research Articles

Targeting decaprenylphosphoryl-β-D-ribose 2'-epimerase for Innovative Drug Development Against Mycobacterium Tuberculosis Drug-Resistant Strains.

Tuberculosis (TB) remains a global health challenge with the emergence of drug-resistant Mycobacterium tuberculosis variants, necessitating innovative drug molecules. One potential target is the cell wall synthesis enzyme decaprenylphosphoryl-β-D-ribose 2'-epimerase (DprE1), crucial for virulence and survival. This study employed virtual screening of 111 Protein Data Bank (PDB) database molecules known for their inhibitory biological activity against DprE1 with known IC50 values. Six compounds, PubChem ID: 390820, 86287492, 155294899, 155522922, 162651615, and 162665075, exhibited promising attributes as drug candidates and validated against clinical trial inhibitors BTZ043, TBA-7371, PBTZ169, and OPC-167832. Concurrently, this research focused on DprE1 mutation effects using molecular dynamic simulations. Among the 10 mutations tested, C387N significantly influenced protein behavior, leading to structural alterations observed through root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), radius of gyration (Rg), and solvent-accessible surface area (SASA) analysis. Ligand 2 (ID: 390820) emerged as a promising candidate through ligand-based pharmacophore analysis, displaying enhanced binding compared with reference inhibitors. Molecular dynamic simulations highlighted ligand 2's interaction with the C387N mutation, reducing fluctuations, augmenting hydrogen bonding, and influencing solvent accessibility. These collective findings emphasize ligand 2's efficacy, particularly against severe mutations, in enhancing protein-ligand complex stability. Integrated computational and pharmacophore methodologies offer valuable insights into drug candidates and their interactions within intricate protein environments. This research lays a strategic foundation for targeted interventions against drug-resistant TB, highlighting ligand 2's potential for advanced drug development strategies.

Efficient GPU computation of large protein Solvent-Excluded Surface.

The Solvent-Excluded Surface (SES) is an essential representation of molecules which is massively used in molecular modeling and drug discovery since it represents the interacting surface between molecules. Based on its properties, it supports the visualization of both large scale shapes and details of molecules. While several methods targeted its computation, the ability to process large molecular structures to address the introduction of big complex analysis while leveraging the massively parallel architecture of GPUs has remained a challenge. This is mostly caused by the need for consequent memory allocation or by the complexity of the parallelization of its processing. In this paper, we leverage the last theoretical advances made for the depiction of the SES to provide fast analytical computation with low impact on memory. We show that our method is able to compute the complete surface while handling large molecular complexes with competitive computation time costs compared to previous works.

Investigation of the new substitution glycine to alanine within the Kringle-2 domain of reteplase: a molecular dynamics study.

Recombinant plasminogen activator (r-PA) consists of the Kringle-2 and protease domains of human tissue-type plasminogen. It is used clinically to treat coronary artery thrombosis and acute myocardial infarction. However, the expression and production of reteplase (r-PA) are limited due to its susceptibility to proteolysis during manufacturing processes. Therefore, efforts have been made to address this limitation. To enhance the conformational stability of r-PA and increase its resistance to proteolysis, we used Gly 6 Ala substitutions in the Kringle-2 domain through in silico . We created an in silico mutant collection with eight structures, incorporating four designated mutations (R103S, G39A, G53A, and G55A). Using MODELLER software and homology modeling, we developed three-dimensional structures for two Kringle-2 and tissue plasminogen activator protease domains, including the wild noncleavable form (R103S) and mutants with all four designated mutations. We assessed protein stability using a dynamic cross-correlation matrix by extracting global properties such as Root Mean Square Deviation (RMSD) and Root Mean Square Fluctuation (RMSF) from trajectory files. The findings revealed that a single glycine-alanine substitution (G39A) enhanced the conformational stability of r-PA, as evidenced by improvements in RMSD, RMSF, radius of gyration, surface accessibility, hydrogen bond formation, eigenvector projection, and density analysis. The conformational stability of r-PA conferred by glycine replacement with alanine may decrease the propensity for proteolysis in protease - rich environments across various recombinant systems and potentially enhance its production and expression levels.

Overcoming microbial resuscitation using stable ultrafine gold nanosystems.

While ultrafine gold nanosystems (UGNs) are being extensively studied for their antimicrobial activities, hitherto, no report is available on their propensity towards mitigating bacterial resuscitation-a potential factor contributing to the antimicrobial resistance. The investigations herein with two categories of gold nanosystems-modulated for their stability and surface accessibility through glutathione capping-have provided insights into overcoming resuscitation. Additionally, the study cautions that even moderate resistance development in bacteria exposed to nanosystems can result in significant cross-resistance against conventional antibiotics.

Hierarchical porous carbon guided by constructing organic-inorganic interpenetrating polymer networks to facilitate performance of zinc hybrid supercapacitors

Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics, holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hybrid supercapacitors (ZHC). Herein, we fabricate a series of dynamics-oriented hierarchical porous carbons derived from the unique organic-inorganic interpenetrating polymer networks. The interpenetrating polymer networks are obtained through physically knitting polyferric chloride (PFC) network into the highly crosslinked resorcinol-formaldehyde (RF) network. Instead of covalent bonding, physical interpenetrating force in such RF-PFC networks efficiently relieves the RF skeleton shrinkage upon pyrolysis. Meanwhile, the in-situ PFC network sacrifices as a structure-directing agent to suppress the macrophase separation, and correspondingly 3D hierarchical porous structure with plentiful ion-diffusion channels (pore volume of 1.35 cm3/g) is generated in the representative HPC4via nanospace occupation and swelling effect. Further removal of Fe fillers leaves behind a large accessible specific surface area of 1550 m2/g for enhanced Zn-ion adsorption. When used as the cathode for ZHC, HPC4 demonstrates a remarkable electrochemical performance with a specific capacity of 215.1 mAh/g at 0.5 A/g and a high Zn2+ ion diffusion coefficient of 11.1 × 10−18 cm2/s. The ZHC device yields 117.0 Wh/kg energy output at a power density of 272.1 W/kg, coupled with good cycle lifespan (100,000 cycles@10 A/g). This work inspires innovative insights to accelerate Zn diffusion dynamics by structure elaboration towards high-capacity cathode materials.

Shearing-induced formation of Au nanowires.

Shearing-induced nucleation is known in our daily lives, yet rarely discussed in nano-synthesis. Here, we demonstrate an unambiguous shearing-induced growth of Au nanowires. While in static solution Au would predominately deposit on pre-synthesized triangular nanoplates to form nano-bowls, the introduction of stirring or shaking gives rise to nanowires, where an initial nucleation could be inferred. Under specific growth conditions, CTAB is responsible for stabilizing the growth materials and the resulting oversaturation promotes shearing-induced nucleation. At the same time, all Au surfaces are passivated by ligands, so that the growth materials are diverted to relatively fresher sites. We propose that the different degrees of "focused growth" in active surface growth could be represented by watersheds of different slopes, so that the subtle differences between neighbouring sites would set course to opposite pathways, with some sites becoming ever more active and others ever more inhibited. The shearing-induced nuclei, with their initially ligand-deficient surface and higher accessibility to growth materials, win the dynamic inter-particle competition against other sites, explaining the dramatic diversion of growth materials from the seeds to the nanowires.

Development and test of highly accurate endpoint free energy methods. 3: partition coefficient prediction using a Poisson-Boltzmann method combined with a solvent accessible surface area model for SAMPL challenges.

Accurately predicting solvation free energy is the key to predict protein-ligand binding free energy. In addition, the partition coefficient (log P), which is an important physicochemical property that determines the distribution of a drug in vivo, can be derived directly from transfer free energies, i.e., the difference between solvation free energies (SFEs) in different solvents. Within the Statistical Assessment of the Modeling of Proteins and Ligands (SAMPL) 9 challenge, we applied the Poisson-Boltzmann (PB) surface area (SA) approach to predict the toluene/water transfer free energy and partition coefficient (log Ptoluene/water) from SFEs. For each solute, only a single conformation automatically generated by the free software Open Babel was used. The PB calculation directly adopts our previously optimized boundary definition - a set of general AMBER force field 2 (GAFF2) atom-type based sphere radii for solute atoms. For the non-polar SA model, we newly developed the solvent-related molecular surface tension parameters γ and offset b for toluene and cyclohexane targeting experimental SFEs. This approach yielded the highest predictive accuracy in terms of root mean square error (RMSE) of 1.52 kcal mol-1 in transfer free energy for 16 small drug molecules among all 18 submissions in the SAMPL9 blind prediction challenge. The re-evaluation of the challenge set using multi-conformation strategies based on molecular dynamics (MD) simulations further reduces the prediction RMSE to 1.33 kcal mol-1. At the same time, an additional evaluation of our PBSA method on the SAMPL5 cyclohexane/water distribution coefficient (log Dcyclohexane/water) prediction revealed that our model outperformed COSMO-RS, the best submission model with RMSEPBSA = 1.88 versus RMSECOSMO-RS = 2.11 log units. Two external log Ptoluene/water and log Pcyclohexane/water datasets that contain 110 and 87 data points, respectively, are collected for extra validation and provide an in-depth insight into the error source of the PBSA method.

Enzymatic Performance of Aspergillus oryzae α-Amylase in the Presence of Organic Solvents: Activity, Stability, and Bioinformatic Studies.

Enzymatic reactions can be modulated by the incorporation of organic solvents, leading to alterations in enzyme stability, activity, and reaction rates. These solvents create a favorable microenvironment that enables hydrophobic reactions, facilities enzyme-substrate complex formation, and reduces undesirable water-dependent side reactions. However, it is crucial to understand the impact of organic solvents on enzymatic activity, as they can also induce enzyme inactivation. In this study, the enzymatic performance of Aspergillus oryzae α-amylase (Taka-amylase) in various organic solvents both experimentally and computationally was investigated. The results demonstrated that ethanol and ether sustain Taka-amylase activity up to 20% to 25% of the organic solvents, with ether providing twice the stability of ethanol. Molecular dynamics simulations further revealed that Taka-amylase has a more stable structure in ether and ethanol relative to other organic solvents. In addition, the analysis showed that the loop located near the active site in the AB-domain is a vulnerable site for enzyme destabilization when exposed to organic solvents. The ability of Taka-amylase to preserve the secondary loop structure in ether and ethanol contributed to the enzyme's activity. In addition, the solvent accessibility surface area of Taka-amylase is distributed throughout all enzyme structures, thereby contributing to the instability of Taka-amylase in the presence of most organic solvents.

Molecular mechanisms involved in the destabilization of two types of R3-R4 tau fibrils associated with chronic traumatic encephalopathy by Fisetin.

Chronic traumatic encephalopathy is a neurodegenerative tauopathy pathologically characterized by fibrillary tau aggregates in the depth of sulci. Clearing fibrous tau aggregates is considered a promising strategy in the treatment of CTE. Fisetin (FS), a natural polyphenolic small molecule, was confirmed to disassociate the tau filaments in vitro. However, the molecular mechanisms of FS in destabilizing the CTE-related R3-R4 tau fibrils remain largely unknown. In this study, we compared the atomic-level structural differences of the two types of CTE-related R3-R4 tau fibrils and explored the influence and molecular mechanisms of FS on the two types of fibrils by conducting multiple molecular dynamics (MD) simulations. The results reveal that the type 1 fibril displays higher structural stability than the type 2 fibril, with a lower root-mean-square-fluctuation value and higher β-sheet structure probability. FS can destabilize both types of fibrils by decreasing the β-sheet structure content, interrupting the mainchain H-bond network, and increasing the solvent accessible surface area and β7-β8 angle of the fibrils. H-bonding, π-π stacking and cation-π are the common interactions driving FS molecules binding on the two types of fibrils, while the hydrophobic interaction occurs only in the type 2 fibril. Due to the relatively short simulation time, our study captures the early molecular mechanisms. However, it does provide beneficial information for the design of drugs to prevent or treat CTE.

Cadmium activation of wild-type and constitutively active estrogen receptor alpha.

The estrogen receptor alpha (ERα) plays a central role in the etiology, progression, and treatment of breast cancers. Constitutively activating somatic mutations Y537S and D538G, in the ligand binding domain (LBD) of ESR1, are associated with acquired resistance to endocrine therapies. We have previously shown that the metalloestrogen calcium activates ERα through an interaction with the LBD of the receptor. This study shows that cadmium activates ERα through a mechanism similar to calcium and contributes to, and further increases, the constitutive activity of the ERα mutants Y537S and D538G. Mutational analysis identified C381, N532A, H516A/N519A/E523A, and E542/D545A on the solvent accessible surface of the LBD as possible calcium/metal interaction sites. In contrast to estradiol, which did not increase the activity of the Y537S and D538G mutants, cadmium increased the activity of the constitutive mutants. Mutation of the calcium/metal interaction sites in Y537S and D538G mutants resulted in a significant decrease in constitutive activity and cadmium induced activity. Mutation of calcium/metal interaction sites in wtERα diminished binding of the receptor to the enhancer of estrogen responsive genes and the binding of nuclear receptor coactivator 1 and RNA polymerase II. In contrast to wtERα, mutation of the calcium/metal interaction sites in the Y537S and D538G mutants did not diminish binding to DNA but prevented a stable interaction with the coactivator and polymerase. Growth assays further revealed that calcium channel blockers and chelators significantly decreased the growth of MCF7 cells expressing these constitutively active mutants. Taken together, the results suggest that exposure to cadmium plays a role in the etiology, progression, and response to treatment of breast cancer due, in part, to its ability to activate ERα.

Morphology regulation of conductive metal-organic frameworks in situ grown on graphene oxide for high-performance supercapacitors.

In this work, nickel-catecholate (Ni-CAT) nanorods were in situ compounded on graphene oxide (GO) to form a composite Ni-CAT@GO (NCG) with a special "blanket-shape" structure, which was used as an electrode material for supercapacitors. The morphology of Ni-CATs in situ grown on GO was modulated by introducing various contents of GO. With increasing GO, the length of nanorods of Ni-CATs is obviously shortened, and the charge transfer resistance of NCG is significantly reduced as the GO content is relatively low while it increases with further addition of GO, because excessive GO in NCG results in smaller crystal sizes accompanied by smaller stacking pores. Both the over-long Ni-CAT nanorods and the smaller stacking pores can restrict the accessible surface areas for the electrolyte. Optimal nanorod sizes are crucial to achieve good electrochemical performance for electrode materials. Galvanostatic charge-discharge analysis of NCG electrodes shows that their capacity initially increases and then decreases with the addition of more and more GO, and Ni-CAT@GO-0.5 (NCG0.5) with minimal charge transfer resistance exhibits the best electrochemical performance. The results demonstrate that the NCG0.5 electrode with optimal morphology possesses an excellent capacitance of 563.8 F g-1 at 0.5 A g-1 and a good rate performance of 61.9% at 10 A g-1, indicating that Ni-CAT@GO is a new type of promising electrode material for supercapacitors based on conductive metal-organic frameworks.

Controllable synthesis of flower-like hierarchical porous TiO2 at room temperature and its affinity application.

Flower-like particles have attracted much attention due to their efficient surface accessible sites and unique hierarchical porous structure. However, their synthesis is usually challenging and requires complex procedures. Herein, we present a simple method for rapid preparation of flower-like hierarchical porous TiO2 (FHP-TiO2) at room temperature for the first time. This method can accurately control the size of FHP-TiO2 from 150 nm to 400 nm by combining co-assembly and Stober reaction. The formation mechanism and influencing factors of FHP-TiO2 were systematically investigated, and its excellent metal oxide affinity was confirmed by theoretical calculations. Due to its hierarchical porous structure, large surface area and high specificity performance, FHP-TiO2 served as an appealing restricted-access adsorbent for specific and efficient enrichment of molecules with phosphate groups in a complex sample matrix, thereby realizing the quantitative analysis of these important biomolecules by coupling with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Moreover, compared with other morphologies (rough surface, and hollow dendritic and mesoporous structure) of TiO2 and flower-like SiO2, FHP-TiO2 showed the best affinity binding ability. This research not only presents a novel approach for tunable room-temperature synthesis of FHP-TiO2 with different sizes, but also expands the application of FHP-TiO2 as an appealing sample-enricher for food safety monitoring and early disease diagnosis.

Customizable ligand exchange on the surface of gold nanotriangles enables their application in LSPR-based sensing.

Nanomaterials made of noble metals have been actively utilized in sensorics and bioanalytics. Nanoparticles of anisotropic shapes are promising for increasing sensitivity due to the generated hotspots of electron density. Such structures can be effectively manufactured by a relatively accessible colloidal synthesis. However, the shape control requires the attachment of a surfactant on specific crystal facets during their growth. Commonly used cetrimonium halides form a closely packed bilayer, lowering the surface accessibility for subsequent (bio)functionalization steps. While there are numerous studies on functionalizing gold nanospheres, novel materials, such as nanotriangles (AuNTs), often require thorough studies to adapt the existing procedures. This is mainly caused by the incomplete characterization of initial nanoparticle colloids in empirically developed protocols. Herein, we report a rational approach utilizing the surface area of AuNTs as a function of both their dimensions and concentration, determined with an express UV-VIS analysis. We demonstrate its efficiency for the exchange of cetyltrimethylammonium chloride (CTAC) with polystyrene sulfonate (PSS) and with biocompatible citrate using direct and indirect methods, respectively. Fourier-transform infrared spectroscopy unequivocally proves the ligand exchange. Such functionalization allows evaluating the bulk refractive index sensitivity of AuNTs as a measure of their potential in LSPR-based sensing.

In English

Features of interfacial adsorbate/adsorbent phenomena depend on several factors: particulate morphology, texture, and structure of adsorbents, molecular weight, shape, and polarity of adsorbates; as well as prehistory of adsorbents pretreated under different conditions. All these factors could affect the efficiency of practical applications of not only adsorbents but also polymer fillers, carriers, catalysts, etc. Interactions of nonpolar nitrogen, hexane, benzene, weakly polar acetonitrile, and polar diethylamine, triethylamine, and water with individual (silica, alumina), binary (silica/alumina (SA)) and ternary (alumina/silica/titania, AST) nanooxides were studied using experimental and theoretical methods to elucidate the influence of the morphological and textural characteristics and surface composition of the materials on the adsorption phenomena. The specific surface area SX / ratio (X is an adsorbate) changes from 0.7 for hexane adsorbed onto amorphous silica/alumina SA8 with 8 wt. % Al2O3 (degassed at 200 °C) to 1.9 for acetonitrile adsorbed onto pure fumed alumina (treated at 900 °C). These changes are relatively large because of variations in orientation, lateral interactions, and adsorption compressing of organic molecules interacting with surfaces characterized by certain set and amounts of various active sites, as well as due to changes in the accessibility of pore surface for probe molecules of different sizes. Larger SX / > 1 values are observed for complex fumed oxides with larger primary nanoparticles, greater surface roughness, hydrophilicity, and Brønsted and Lewis acidity of a surface. Both polar and nonpolar adsorbates can change the morphology and texture of aggregates of oxide nanoparticles, e.g., swelling of structures, compacted during various pretreatments, upon the adsorption of liquids. The studied effects should be considered upon practical applications of adsorbents, especially “soft” fumed oxides.

Inhibitor design for TMPRSS2: insights from computational analysis of its backbone hydrogen bonds using a simple descriptor

Transmembrane protease serine 2 (TMPRSS2) is an important drug target due to its role in the infection mechanism of coronaviruses including SARS-CoV-2. Current understanding regarding the molecular mechanisms of known inhibitors and insights required for inhibitor design are limited. This study investigates the effect of inhibitor binding on the intramolecular backbone hydrogen bonds (BHBs) of TMPRSS2 using the concept of hydrogen bond wrapping, which is the phenomenon of stabilization of a hydrogen bond in a solvent environment as a result of being surrounded by non-polar groups. A molecular descriptor which quantifies the extent of wrapping around BHBs is introduced for this. First, virtual screening for TMPRSS2 inhibitors is performed by molecular docking using the program DOCK 6 with a Generalized Born surface area (GBSA) scoring function. The docking results are then analyzed using this descriptor and its relationship to the solvent-accessible surface area term ΔGsa of the GBSA score is demonstrated with machine learning regression and principal component analysis. The effect of binding of the inhibitors camostat, nafamostat, and 4-guanidinobenzoic acid (GBA) on the wrapping of important BHBs in TMPRSS2 is also studied using molecular dynamics. For BHBs with a large increase in wrapping groups due to these inhibitors, the radial distribution function of water revealed that certain residues involved in these BHBs, like Gln438, Asp440, and Ser441, undergo preferential desolvation. The findings offer valuable insights into the mechanisms of these inhibitors and may prove useful in the design of new inhibitors.

Screening and unveiling antibacterial mechanism of dandelion phenolic extracts against Staphylococcus aureus by inhibiting intracellular Na+–K+ ATPase based on molecular docking and molecular dynamics simulation

Staphylococcus aureus is one of the most frequently food-contaminated incidence of healthcare-associated Gram-positive bacteria. The antibacterial function and mechanism of phenolic compounds from dandelion are still unclear. Herein, this work aims to screen one of dandelion phenolic extracts with the strongest antibacterial function from its organ such as flower, stem, leaf and root, and to reveal its antibacterial mechanism. The results indicated dandelion flower phenolic extract (DFPE) containing the highest content of caffeic acid, followed by luteolin and luteolin-7-O-glucoside. They, especially caffeic acid and luteolin-7-O-glucoside, played a key role in making the bacterial cellular-membrane ruptured against the bacteria. The leakage of the intracellular substances (adenosine triphosphate and Na+–K+ ATPase) was further confirmed. Conventional hydrogen bond, pi-anion, pi-alkyl were involved in the interaction between caffeic acid or luteolin-7-O-glucoside and Na+–K+ ATPase. Additionally, the dynamic equilibrium of the liganded ATPase complex were achieved after 105 ns, and the lower values from the radius of gyration and solvent accessible surface area in the complex demonstrated the highly tight and compact structure of the liganded protein. The highest free binding energy (ΔGbind = −47.80 kJ/mol) between Na+–K+ ATPase and luteolin-7-O-glycloside was observed. Overall, DFPE can be used as an effective anti-bacterial agent due to the contribution of its bioactive ingredients such as caffeic acid and luteolin-7-O-glucoside for membrane-breaking. Communicated by Ramaswamy H. Sarma

Natural sapogenins as potential inhibitors of aquaporins for targeted cancer therapy: computational insights into binding and inhibition mechanism

Aquaporins (AQPs) are membrane proteins that facilitate the transport of water and other small molecules across biological membranes. AQPs are involved in various physiological processes and pathological conditions, including cancer, making them as potential targets for anticancer therapy. However, the development of selective and effective inhibitors of AQPs remains a challenge. In this study, we explored the possibility of using natural sapogenins, a class of plant-derived aglycones of saponins with diverse biological activities, as potential inhibitors of AQPs. We performed molecular docking, dynamics simulation and binding energy calculation to investigate the binding and inhibition mechanism of 19 sapogenins against 13 AQPs (AQP0-AQP13) that are overexpressed in various cancers. Our results showed that out of 19 sapogenins, 8 (Diosgenin, Gitogenin, Tigogenin, Ruscogenin, Yamogenin, Hecogenin, Sarsasapogenin and Smilagenin) exhibited acceptable drug-like characteristics. These sapogenin also exhibited favourable binding affinities in the range of −7.6 to −13.4 kcal/mol, and interactions within the AQP binding sites. Furthermore, MD simulations provided insights into stability and dynamics of the sapogenin-AQP complexes. Most of the fluctuations in binding pocket were observed for AQP0-Gitogenin and AQP4-Diosgenin. However, remaining protein–ligand complex showed stable root mean square deviation (RMSD) plots, strong hydrogen bonding interactions, stable solvent-accessible surface area (SASA) values and minimum distance to the receptor. These observations suggest that natural sapogenin hold promise as novel inhibitors of AQPs, offering a basis for the development of innovative therapeutic agents for cancer treatment. However, further validation of the identified compounds through experiments is essential for translating these findings into therapeutic applications. Communicated by Ramaswamy H. Sarma

A Mesoporous Magnetic Fe3O4/BioMOF-13 with a Core/Shell Nanostructure for Targeted Delivery of Doxorubicin to Breast Cancer Cells.

In the current project, magnetic Bio-MOF-13 was used as an efficient carrier for the targeted delivery and controlled release of doxorubicin (DOX) to MDA-MB-231 cells. Magnetic Bio-MOF-13 was prepared by two strategies and compared to determine the optimal state of the structure. In the first path, Bio-MOF-13 was grown in situ on the surface of Fe3O4 nanoparticles (core/shell structure), while in the second method, the two presynthesized materials were mixed together (surface composite). Core/shell structure, among prepared nanocomposites, was chosen for biological evaluation due to its favorable structural features like a high accessible surface area and pore volume. Also, it is highly advantageous for drug release due to its ability to selectively release DOX in the acidic pH of breast cancer cells, while preventing any premature release in the neutral pH of the blood. Drug release from the carrier structure is precisely controlled not only by pH but also by an external magnetic field, guaranteeing accurate drug delivery at the intended location. Confocal microscopy and flow cytometry assay clearly confirms the increase in drug concentration in the MDA-MB-231 cell line after external magnet applying. This point, along with the low toxicity of the carrier components, makes it a suitable candidate for injectable medicine. According to MTT results, the percentage of viable MDA-MB-231 cells after treatment with 10 μL of DOX@Fe3O4/Bio-MOF-13 core/shell composite in different concentrations, in the presence and absence of magnetic field is 0.87 ± 0.25 and 2.07 ± 0.15, respectively. As a result, the DOX@Fe3O4/Bio-MOF-13 core/shell composite was performed and approved for targeted drug delivery and magnetic field-assisted controlled release of DOX to the MDA-MB-231 cell line.

Waste frying oil derived carbon nano-onions as a cost-effective cathode material for high-voltage zinc-ion hybrid supercapacitors

Energy crisis and environmental pollution are two major worldwide issues that can be solved by developing sustainable, commercial, and long-durability energy storage systems from the reutilization of waste material. Waste frying oil, a known waste, is used as a carbon source for the synthesis of carbon nano-onions (CNOs) using economically viable and environmentally friendly wick pyrolysis techniques. The as-synthesized CNOs were used as a cost-effective cathode in zinc-ions hybrid supercapacitors (Zn–HSCs). CNOs with a fractal-like structure in an interconnected network and more accessible active available surface area provide great advantage as a cathode to fabricate Zn–HSCs. The CNOs-based active cathode material in aqueous Zn–HSCs presents a high specific capacitance of 342 F g−1 at a current density of 0.5 A g−1 under a high working potential window (0–1.9 V). Zn–HSCs achieve a maximum 8.2 kW kg−1 of power density and 164.33 W h kg−1 of energy density. More significantly, excellent long-term durability with 83 % of capacity retention and 100 % retention of coulombic efficiency was also achieved after 10,000 cycles at a high 10 A g−1 of current density. The overall work represents a way of utilizing waste frying oil as a cost-effective and efficient cathode material for aqueous Zn–HSCs, which could aid-in the commercialization of Zn–HSCs.

Hydrogen Evolution Using a Highly Efficient MoS2-Carbon Nano-Onion Heterostructure Electrocatalyst

Hydrogen, a clean and sustainable energy source, can be produced by electrochemical water splitting using an electrocatalyst. However, developing an inexpensive, efficient catalyst for hydrogen evolution reaction (HER) is a challenge as it is difficult to obtain an electrocatalyst with a large accessible active surface. In this study, a sulfide of a non-noble metal, molybdenum, was employed as an electrocatalyst. Due to the restacking of 2D MoS2 layers, access to the active area was limited. This drawback of the 1T MoS2 catalyst was overcome by incorporating the carbon nano-onion (CNO). The unique MoS2-CNO heterostructure formed by growing a few-layered 2D 1T MoS2 on the CNO core facilitated smooth and barrier-free charge transfer through the heterojunction formation. This heterostructure mitigated restacking and maintained structural stability, providing a long-term high-performance catalyst. This MoS2-CNO exhibited an excellent HER performance with an overpotential of 53 mV vs. RHE and a Tafel slope of 40.8 mV dec-1 for over 25 h, showing it one of the best HER catalysts, next to platinum. This study highlights a new, highly stable, highly performing non-noble metal catalyst for electrochemical water splitting applications.