Improvement of Hydrogen Adsorption on the Simultaneously Decorated Graphene Sheet with Titanium and Palladium Atoms.

In this study, a simultaneously decorated graphene sheet with titanium (Ti) and palladium (Pd) atoms is proposed to improve hydrogen adsorption uptake. Density functional theory (DFT) with a DFT-D3 correction dispersion study was applied. Initially, the hydrogen adsorption energy, energy band gap, partial density of state (PDOS), thermal stability, and H2 desorption temperature for Ti-decorated, Pd-decorated, and Ti-Pd-decorated graphene sheets were investigated. Clustering formation for the Ti-decorated graphene sheet was examined in detail. Grand canonical Monte Carlo (GCMC) simulation was applied to examine the hydrogen adsorption isotherm. Simulation results showed that the hydrogen adsorption energy and desorption temperature of the Ti-decorated graphene sheet are -0.61 eV and 765.4 K, respectively, which are significantly higher than those of the Pd-decorated graphene sheet (-0.108 eV and 135.5 K). However, Ti atoms form clusters when their distances from each other are less than 6 Å. Inserting adaptable metal atoms such as Pd into the Ti-decorated graphene adjusts the hydrogen adsorption energy to -0.544 eV and the desorption temperature to 627.4 K. In addition, the values of Gibbs free energy changes (ΔG) of metal adsorption showed that the Ti-Pd graphene sheet has good stability at different temperatures. Calculated hydrogen adsorption isotherm using the GCMC method approved the suitable performance of the Ti-Pd-decorated graphene sheet for hydrogen adsorption. At the pressure of 60 bar and temperature of 298 K, the hydrogen adsorption content increases from 1.49 wt % on the Ti-decorated graphene sheet with cluster to 2.06 wt % on the Ti-Pd-decorated graphene sheet. Finally, Ti-Pd-decorated graphene sheet was proposed as a novel adsorbent in the hydrogen storage industry.

Indocyanine green-loaded N-doped carbon quantum dot nanoparticles for effective photodynamic therapy and cell imaging of melanoma cancer: In vitro, ex vivo and in vivo study.

N-doped carbon quantum dot (CQD) nanoparticle was prepared as a novel nanocarrier with excellent solubility, stability, and high quantum yield to overcome Indocyanine Green (ICG) obstacle in photodynamic therapy (PDT) with simultaneous cell imaging property. Cell culture study and In vivo assessments on the C57BL/6 mice containing melanoma cancer cells was performed. Results showed that CQD size after ICG loading slightly enhanced from 24.55 nm to 42.67 nm. Detection of reactive oxygen species (ROS) test demonstrated that CQD improved ICG photo-stability and ROS generation capacity upon laser irradiation. Cell culture study illustrated that ICG@CQD could decrease the survival rate of melanoma cancer cells of B16F10 cell line from 48% for pure ICG drug to 28% for ICG@CQD. Captured images by confocal microscopy approved more cellular uptake of ICG@CQD and more qualified cell imaging ability of the nanocarrier. In vivo assessments on the C57BL/6 mice containing melanoma cancer cells displayed the obvious inhibitory effect of the tumor growth for ICG@CQD in comparison to free ICG. In vivo fluorescence images confirmed that ICG@CQD accumulates remarkably more than free ICG in the tumor region. In conclusion, ICG@CQD is proposed as an innovative nanocarrier with great potential for PDT and diagnosis.

Utilizing the sublingual form of squalene in COVID-19 patients: a randomized clinical trial.

In this study, the efficacy of sublingual squalene in decreasing the mortality rate among patients with COVID-19 was investigated. Squalene was extracted from pumpkin seed oil with a novel method. Then, the microemulsion form of squalene was prepared for sublingual usage. In the clinical study, among 850 admitted patients, 602 eligible COVID-19 patients were divided in two groups of control (N = 301) and cases (N = 301) between Nov 2021 and Jan 2022. Groups were statistically the same in terms of age, sex, BMI, lymphocyte count on 1st admission day, hypertension, chronic kidney disease, chronic respiratory disease, immunosuppressive disease, and required standard treatments. The treatment group received five drops of sublingual squalene every 4 h for 5 days plus standard treatment, while the control group received only standard treatment. Patients were followed up for 30 days after discharge from the hospital. The sublingual form of squalene in the microemulsion form was associated with a significant decrease in the mortality rate (p < 0.001), in which 285 (94.7%) cases were alive after one month while 245 (81.4%) controls were alive after 1 month of discharge from the hospital. In addition, squalene appears to be effective in preventing re-hospitalization due to COVID-19 (p < 0.001), with 141 of controls (46.8%) versus 58 cases (19.3%). This study suggests sublingual squalene in the microemulsion as an effective drug for reducing mortality and re-hospitalization rates in COVID-19 patients.Trial Registration Number: IRCT20200927048848N3.

A Novel Topical Formulation of the Leishmaniasis Drug Glucantime as a Nanostructured Lipid Carrier-Based Hydrogel.

Leishmaniasis is a parasitic disease caused by Leishmania parasites. Meglumine antimoniate, or Glucantime, is the primary drug used to treat this disease. Glucantime with a standard painful injection administration route has high aqueous solubility, burst release, a significant tendency to cross into aqueous medium, rapid clearance from the body, and insufficient residence time at the injury site. Topical delivery of Glucantime can be a favorable option in the treatment of localized cutaneous leishmaniasis. In this study, a suitable transdermal formulation in the form of nanostructured lipid carrier (NLC)-based hydrogel containing Glucantime was prepared. In vitro drug release studies confirmed controllable drug release behavior for hydrogel formulation. An in vivo permeation study on healthy BALB/C female mice confirmed appropriate penetration of hydrogel into the skin and sufficient residence time in the skin. In vivo performance of the new topical formulation on the BALB/C female mice showed a significant improvement in reduction of leishmaniasis wound size, lowering parasites number in lesions, liver, and spleen compared with commercial ampule. Hematological analysis showed a significant reduction of the drug's side effects, including variance of enzymes and blood factors. NLC-based hydrogel formulation is proposed as a new topical administration to replace the commercial ampule.

Dual targeting of Mg/N doped-carbon quantum dots with folic and hyaluronic acid for targeted drug delivery and cell imaging.

Mg/N doped-carbon quantum dots (CQDs) with dual drug targeting and cell imaging properties was synthesized. Mg/N doped-CQDs synthesized by a hydrothermal method. Operating pyrolysis parameters such as temperature, time, and pH were optimized to achieve CQDs with high quantum yield (QY). This CQD applied in cellular imaging. For the first time, dual active targeting of Mg/N doped CQDs performed using folic acid and hyaluronic acid (CQD-FA-HA). Then, epirubicin (EPI) loaded on this nanocarrier as the final complex (CQD-FA-HA-EPI). Cytotoxicity analysis, cellular uptake, and cell photography performed for the complex on three cell lines, including 4T1, MCF-7, and CHO. In vivo studies were performed in BALB/c inbred female mice models bearing breast cancer. Characterization results showed the successful formation of Mg/N doped-CQDs with a high QY of 89.44%. In vitro drug release approved pH dependency of synthesized nanocarrier with a controlled release behavior. Cytotoxicity tests and cellular uptake results demonstrated increased toxicity and absorption into 4T1 and MCF-7 cell lines for targeted nanoparticles compared to free drug. In cell imaging, an increase in the entry of the complex into 4T1 and MCF-7 cells compared to free drug, confirmed the proper function of the synthesized complex. In vivo results indicated that the tumor volume of mice receiving CQD-FA-HA-EPI was the lowest among other studied groups, along with the lowest damage to the liver, spleen, and heart according to the histopathological analysis. Finally, CQD-FA-HA proposed as a novel platform with tumor targeting, drug carrier, and photoluminescence properties.

Molecular dynamics simulation of drug delivery across the cell membrane by applying gold nanoparticle carrier: Flutamide as hydrophobic and glutathione as hydrophilic drugs as the case studies.

In this study, molecular dynamics simulation is applied to investigate drug transport in both pure state and conjugated with neutral gold nanoparticle (AuNP) as a drug carrier inside dipalmitoylphosphatidylcholine (DPPC) membrane. Flutamide (Flu) as a hydrophobic and Glutathione (GSH) as a hydrophilic anticancer drug are selected as the case studies. Dynamics of each drug including adhesion on and penetration into the cell membrane are investigated. Pure and conjugated form of drugs inside the water and near the membrane are studied. Simulation results show that the interaction between drug molecules and DPPC changes after drug conjugating with AuNP. GSH, as a hydrophilic drug, intends to remain above the membrane bilayer and after conjugating with AuNP diffuses inside DPPC. However, hydrophobic Flu molecule likes to diffuse inside DPPC, but after conjugating with AuNP, its diffusion inside the lipid bilayer decreases, and its retention time at the surface of DPPC increases. Presence of Flu-NP at the surface of DPPC could enhance its impact on blocking dihydrotestosterone binding at androgen receptors resulting in tumor cell growth arrest. In addition, the tendency of GSH-NP for diffusion to the DPPC is a positive factor for the successful transport of heavy metals such as AuNP without rapid clearance through either the hepatobiliary pathway or the renal system. In conclusion, such MD simulation results may solve problems in nanomedicine translation and turn into a bridge toward maximizing targeting and minimizing nanotoxicity of metal NPs.

Evaluating the efficacy of extracted squalene from seed oil in the form of microemulsion for the treatment of COVID-19: A clinical study.

This study investigates the effect of the nanostructure of squalene in the form of microemulsion on COVID-19 patients. In this blinded clinical trial, a comparison was made between the efficacy of squalene treatment and controls. A total of 30 COVID-19 patients admitted to the emergency department, and the infection ward was equally allocated to case (n = 15) and control (n = 15) groups according to their age and underlying diseases. The baseline characteristics of subjects, including age, gender, time of treatment onset, underlying condition, white blood cells count, and lymphocyte count were similar (p < 0.05). Baseline laboratory tests and computed tomography (CT) scans were performed for the study groups. The treatment group received 5 mg of intravenous squalene twice a day and standard treatment for 6 days, while controls received only standard treatment. After 6 days of treatment, clinical and CT scan changes were evaluated and compared in intervention and control groups. The need for oxygen therapy (p = 0.020), 2 days of no fever (p = 0.025), cough alleviation (p = 0.010), and lung high-resolution computed tomography improvement (p = 0.033) were significantly different between cases and controls within 7 days of admission. No adverse effects were observed in the treatment group. Our data suggest that squalene could be considered as a potential treatment for COVID-19, and further studies are required to confirm the results.

Enhanced antibacterial activity of uniform and stable chitosan nanoparticles containing metronidazole against anaerobic bacterium of Bacteroides fragilis.

In this paper, the salt-assisted chitosan nanoparticles (CS NPs) containing metronidazole (MTZ) were prepared using the ionic gelation technique in the presence of NaCl. The effect of different concentrations of NaCl on particle size, zeta potential, polydispersity index (PDI), and entrapment efficiency (EE %) was investigated. Also, the stability of MTZ-loaded CS NPs in the absence/presence of NaCl was evaluated over a 6-month storage period. Furthermore, drug release at pH = 7.4 was examined and the corresponding mechanism was explored. Finally, the time-kill assay of free MTZ and salt-assisted MTZ-loaded CS NPs against Bacteroides fragilis was performed by applying the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). It was found that in the presence of 20 mM NaCl, the optimum NPs can be achieved with the particle size of 284 nm, PDI of 0.099, EE% of 57.4 %, and zeta potential of +46.32 mV. More stability of salt-assisted nanoparticles, as well as lower size enhancement versus time, were observed due to higher surface charge density calculated using the Gouy-Chapman theory. The in-vitro drug release profiles demonstrated a more controlled drug release of MTZ from CS NPs compared to free MTZ, because of the shrinkage properties of CS at high pH. The kinetic modeling of drug release approved the Fickian diffusion of drug based on the Korsmeyer-Peppas model. The time-kill plots confirmed the higher antibacterial activity of salt-assisted MZ-loaded CS NPs compared to the free MTZ against B. fragilis bacterium. In conclusion, the salt-assisted MTZ-loaded CS NPs prepared in the presence of a proper concentration of NaCl, can be an acceptable nanoparticle form for designing MTZ drug delivery systems.

Improvement of Pain Relief of Fentanyl Citrate Drug Encapsulated in Nanostructured Lipid Carrier: Drug Formulation, Parameter Optimization, in vitro and in vivo Studies.

INTRODUCTION: In this study, the encapsulation of fentanyl citrate as an opioid drug with hydrophobic nature in the nanostructured lipid carrier (NLC) is performed. METHODS: For encapsulation of fentanyl citrate drug, hot homogenization method is used. The pharmacokinetics of encapsulated fentanyl citrate for pain relief of rats are investigated. The influence of important variables such as the ratio of liquid lipid to the total amount of lipids, surfactant type and concentration on the particle size is investigated using response surface method. RESULTS: Results show that the optimal NLC size is about 90 nm with PDI value around 0.2 and zeta potential of -25±4.01 mV. Characterization analysis of optimal nanostructure shows successful encapsulation of the drug in nanostructure with a spherical morphology of the NLC structure. Results of drug release from commercial fentanyl citrate ampoule and NLC form indicate a control drug release from the NLC within 72 hours in comparison to the commercial ampoule. In vivo studies show that fentanyl citrate-loaded NLC not only has the potential to relieve pain in doses equal to commercial drug but also it can reduce the dose of the drug about 50%. CONCLUSION: In conclusion, NLC form of fentanyl citrate can increase the efficacy of the drug by appropriate drug distribution in the body and can reduce the risks of overdose.

Enhanced bactericidal effect of ceftriaxone drug encapsulated in nanostructured lipid carrier against gram-negative Escherichia coli bacteria: drug formulation, optimization, and cell culture study.

BACKGROUND: Ceftriaxone is one of the most common types of antibiotics used to treat most deadly bacterial infections. One way to alleviate the side effects of medication is to reduce drug consumption by changing the ordinary drug forms into nanostructured forms. In this study, a nanostructured lipid carrier (NLC) containing hydrophilic ceftriaxone sodium drug is developed, and its effect on eliminating gram-negative bacteria Escherichia coli death is investigated. METHODS: Double emulsion solvent evaporation method is applied to prepare NLC. Mathematical modeling based on the solubility study is performed to select the best materials for NLC preparation. Haftyzer-Van Krevelen and Hoy's models are employed for this purpose. Drug release from optimized NLC is examined under in vitro environment. Then, the efficacy of the optimized sample on eliminating gram-negative bacteria Escherichia coli is investigated. RESULTS: Mathematical modeling reveals that both methods are capable of predicting drug encapsulation efficiency trends by chaining solid and liquid lipids. However, Haftyzer-Van Krevelen's method can precisely predict the particle size trend by changing the surfactant types in water and oily phases of emulsions. The optimal sample has a mean particle size of 86 nm and drug entrapment efficiency of 83%. Also, a controlled drug release in prepared nanostructures over time is observed under in-vitro media. The results regarding the effectiveness of optimized NLC in killing Escherichia coli bacteria suggests that by cutting drug dosage of the nanostructured form in half, an effect comparable to that of free drug can be observed at longer times. CONCLUSION: Results confirm that NLC structure is an appropriate alternative for the delivery of ceftriaxone drug with a controlled release behavior.

Enhanced delivery of melatonin loaded nanostructured lipid carriers during in vitro fertilization: NLC formulation, optimization and IVF efficacy.

In this study, the potential of melatonin hormone loaded in nanostructured lipid carriers (Mel-NLCs) in the in vitro fertilization (IVF) environment is investigated by measuring the oocyte maturation, the two-pre-nucleus embryo development, the two-cell stage embryo development, and blastocyst production on the oocytes of mice. Mel-NLCs are prepared using the hot homogenization-ultrasonication method. A response surface method is utilized to determine the best independent variables to obtain nanoparticles with a small particle size and high hormone entrapment efficiency. The optimized nanoparticles have a particle size of 119 nm with a polydispersity index of 0.09 and hormone entrapment efficiency of 94%. Characterization results such as TEM and AFM analysis confirm the spherical and relatively uniform structure of the optimal sample. FTIR and XRD analyses indicate that the hormone is properly loaded within the amorphous nanostructure. Drug release from NLC under the in vitro environment exhibits a biphasic domain including burst release in the first 2 hours and the controlled release in 48 h 92% of the drug is released from nanoparticles in 48 hours, but the same amount of hormone is released from the marketed drug suspension during 2 hours. Results of IVF experiments reveal that the nanostructured form has a positive effect on all IVF parameters compared to the free form of the hormone. In addition, using the hormone nanostructured form can reduce the dosage of the melatonin free form with the same efficacy in the IVF environment. Finally, the nanostructured form of melatonin based on NLC nanostructure can be a good candidate for application in IVF media.

Experimental study and mathematical modeling for encapsulation of fentanyl citrate drug in nanostructured lipid carrier.

The aim of this study is to prepare a nanostructured lipid carrier (NLC) containing Fentanyl Citrate drug. The materials were selected in a way to achieve a nanostructure with lower particle size and higher drug entrapment efficiency. For this purpose, we used two mathematical models, Van Krevelen-Hoftyze and Hoy's methods, which are based on the calculation of solubility parameters. Various NLC formulations are prepared experimentally to validate the mathematical modeling results. Hot homogenization method was used for NLC preparation. DLS, HPLC, TEM and DSC analyses are performed to calculate the size, drug entrapment efficiency, morphology and thermal behavior of particles, respectively. Experimental results suggest that the best NLC formulation has a particle size of 90 nm with a spherical morphology and drug entrapment efficiency of about 82%. A comparison of the mathematical and experimental results exhibits that Van Krevelen-Hoftyzer method is unable to provide an accurate estimation of the decreasing trend of particle size by chaining the components of NLC. However, Hoy's method seems to be suitable for this purpose. Moreover, both mathematical methods could successfully estimate variation trend of drug entrapment efficiency by chaining the NLC components. Results show that surfactants-lipids solubility parameter has a bearing on the nanoparticle size while drug-lipid solubility parameter affects drug entrapment efficiency.Communicated by Ramaswamy H. Sarma.

Formulation, clinical and histopathological assessment of microemulsion based hydrogel for UV protection of skin.

The aim of this study was to prepare a microemulsion based hydrogel containing sesame oil and evaluate its topical application in preventing the harmful effects of UV radiation on the guinea pig's skin using histopathologic and clinical findings. Sesame oil with high antioxidant content and unique chemical and physiological properties is a suitable candidate for the evolution of UV protection on skin. Applying this natural oil in microemulsion formulation containing particles with nanometer size can enhance its efficacy. To prepare a stable microemulsion, it is necessary to select the appropriate surfactants. In this study, first the best combination of hydrophilic surfactant of Tween 80 with various lipophilic surfactants such as Span 20, Span 80 and Span 85 at different surfactant ratios was examined. The microemulsion formulations were assessed for particle size, zeta potential, polydispersity index, refractive index, electrical conductivity, pH value and stability. Results showed that among various samples, microemulsion containing a mixture of Tween 80 and Span 80 with the surfactant ratio of 9:1 was the best sample in terms of stability over time (six months). This sample had a lower particle size of 26.09 nm with a narrow particle size distribution. For topical application, the microemulsion based hydrogel was prepared with 0.6% Carbomer 940 as a gelling agent. The pH value and viscosity of gel formulation were 6.6 and 12.90 Pa.s, respectively, which is appropriate for topical applications. A slight enhancement of particle size inside hydrogel structure was observed after six months of the gel preparation. The clinical evolutions of formulation on guinea pig's skin were included skin scaling, skin irregularity, erythema, skin hyperpigmentation, and edema. Epidermal hyperkeratosis, hyperpigmentation, exocytosis, acanthosis, chromatin discoloration in nucleus of epidermal squamous cells, perifolliculitis, dermal vascular hyperemia, edema and dermal thickness, infiltration of plasma cell lymphocytes and eosinophils into dermis were observed for histopathological investigations. Based on clinical and histopathological examinations, topical application of microemulsion-based hydrogel of sesame oil can effectively prevent skin damage induced by UV radiation and is therefore suitable for skin products.

Prediction of chlortetracycline adsorption on the Fe3O4 nanoparticle using molecular dynamics simulation.

Molecular dynamics (MD) simulation was applied to investigate the adsorption mechanism of chlortetracycline (CTC) antibiotic molecule as the aqueous pollutant on the Fe3O4 nanoparticle (NP). Two different NP sizes with a diameter of about 1.4 nm and 3.5 nm were selected. Initially, the stability of both NPs in water was investigated by calculating radial distribution function curves of NP atoms. Simulation results confirmed the stable crystallographic structures of both NPs. However, small NP induce greater structural stabilization. Then, CTC molecules were adsorbed on NPs surface in various pollutant concentrations. Electrostatic and hydrogen bond were the major types of interactions between CTC molecules and the adsorbent surface. CTC molecules formed a complex with NP surface from their amine side chains; while they were parallel to each other in their aromatic rings and π-π bond between two CTC molecules was formed. Diffusion rate of CTC molecules could predict the adsorption mechanism. At lower concentration of CTC, CTC molecules tend to adsorb on the NP surface. At these concentrations, the diffusion rate of CTC was high. By increasing the CTC concentration, the pollutant agglomeration was enhanced which decreased the diffusion rate. At this time, the surface of NP was saturated. In addition, the results of isotherm curves showed that CTC adsorption on small NPs could be defined with both Langmuir and Freundlich isotherm models, while Freundlich isotherm model was more appropriate for larger NPs. In conclusion, observations confirmed that MD simulation could successfully predict the behavior of CTC adsorption on the Fe3O4 NP surface. Communicated by Ramaswamy H. Sarma.

Data for exploring the effect of parameters on decomposition of gas hydrate structure I.

This article describes initial and final configurations of methane hydrate structure I as PDB file at various cage occupancies and different temperatures. Cage occupancies from full occupancy to 75% at three temperatures of 290 K, 300 K and 310 K are presented. Dissociation behavior of gas hydrate structure I at the temperature of 300 K is shown in changing the potential energy and radial distribution function.

Preparation, characterization and in vitro evaluation of microemulsion of raloxifene hydrochloride.

Raloxifene hydrochloride (RLX) is a selective estrogen receptor modulator which is orally used for treatment of osteoporosis and prevention of breast cancer. The drug has low aqueous solubility and bioavailability. The aim of the present study is to formulate and characterize oil-in-water microemulsion systems for oral delivery of RLX. To enhance the drug aqueous solubility, microemulsion based on sesame oil was prepared. Sesame oil and Tween 80 were selected as the drug solvent oil and surfactant, respectively. In the first and second formulations, Edible glycerin and Span 80 were applied as co-surfactant, respectively. Pseudo-ternary phase diagrams showed that the best surfactant/co-surfactant ratios in the first and second formulations were 4:1 and 9:1, respectively. The particle size of all free drug-loaded and drug loaded samples were in the range of 31.25 ± 0.3 nm and 60.9 ± 0.1 nm, respectively. Electrical conductivity coefficient and refractive index of all microemulsion samples confirmed the formation of oil-in-water type of microemulsion. In vitro drug release profile showed that after 24 hours, 46% and 63% of the drug released through the first formulation in 0.1% (w/v) Tween 80 in distilled water as a release medium and phosphate buffer solution (PBS) at pH = 5.5, respectively. These values were changed to 57% and 98% for the second formulation. Results confirmed that the proposed microemulsion system containing RLX could improve and control the drug release profile in comparison to conventional dosage form.

Preparation, characterization and in-vivo evaluation of microemulsions containing tamoxifen citrate anti-cancer drug.

The aim of this study was to prepare and characterize a new nanocarrier for oral delivery of tamoxifen citrate (TMC) as a lipophilic oral administrated drug. This drug has low oral bioavailability due to its low aqueous solubility. To enhance the solubility of this drug, the microemulsion system was applied in form of oil-in-water. Sesame oil and Tween 80 were used as drug solvent oil and surfactant, respectively. Two different formulations were prepared for this purpose. The first formulation contained edible glycerin as co-surfactant and the second formulation contained Span 80 as a mixed surfactant. The results of characterization showed that the mean droplet size of drug-free samples was in the range of 16.64-64.62nm with a PDI value of <0.5. In a period of 6months after the preparation of samples, no phase sedimentation was observed, which confirmed the high stability of samples. TMC with a mass ratio of 1% was loaded in the selected samples. No significant size enlargement and drug precipitation were observed 6months after drug loading. In addition, the drug release profile at experimental environments in buffers with pH=7.4 and 5.5 showed that in the first 24h, 85.79 and 100% of the drug were released through the first formulation and 76.63 and 66.42% through the second formulation, respectively. The in-vivo results in BALB/c female mice showed that taking microemulsion form of drug caused a significant reduction in the growth rate of cancerous tumor and weight loss of the mice compared to the consumption of commercial drug tablets. The results confirmed that the new formulation of TMC could be useful for breast cancer treatment.

Molecular dynamics simulation of doxorubicin adsorption on a bundle of functionalized CNT.

In this study, molecular dynamics simulation is used to investigate the adsorption of an anticancer drug, doxorubicin, on bundles of functionalized single-walled carbon nanotubes (SWNTs) in an aqueous solution. Carboxylic group has been selected as the functional group. Molecular dynamics (MD) simulations are performed for both separated systems containing a SWNT bundle and a functionalized carbon nanotube bundle, and results are compared with existing experimental data. MD results show that doxorubicin can be adsorbed on CNTs using different methods such as entrapment within CNT bundle, attachment to the side wall of the CNT, and adsorption on the CNT inner cavity. For functionalized CNT, the adsorption of drugs on the functional groups is essential for predicting the enhancement of drug loading on the functionalized nanotubes. Furthermore, the adsorption behavior of doxorubicin on CNTs is fitted with Langmuir and Freundlich isotherm models. The results show that Langmuir model can predict the adsorption behavior of doxorubicin on CNTs more accurately than Freundlich model does. As predicted by this isotherm model, the adsorption process of doxorubicin on CNTs is relatively difficult, but it can be improved by increasing the functional groups on the CNTs surface.

Hybrid molecular simulation of methane storage inside pillared graphene.

In this study, a hybrid molecular dynamics--grand canonical Monte Carlo simulation is carried out to investigate the storage capacity of methane in a new nanostructure adsorbent called pillared graphene. This new nanostructure is composed of graphene sheets in parallel with vertical carbon nanotubes (CNTs), which act as their holders. The adsorption ability of this new structure is compared to graphene sheets to evaluate its potential for methane storage. The results show that in a specific adsorbent volume, applying pillared graphene increases the number of adsorbed methane up to 22% in comparison to graphene sheets. Given the application of various isotherm models such as Langmuir, Freundlich, Sips, and Toth and calculation of their parameters, it is predicted that methane adsorption on pillared graphene displays a heterogeneous behavior. Furthermore, the effects of geometry parameters such as CNTs diameter, the number of CNTs, and graphene sheets layer spacing on the methane uptake are investigated. The results show that the pillared graphene containing 1 CNT per 30 nm(2) graphene sheet areas provides the best configuration for methane adsorption. This optimum structure is characterized by a small diameter of about 0.938 nm and an optimal layer spacing of about 1.2 nm. Finally, our results show that this kind of pillared structure can be suitable for methane storage.

Selective adsorption of metoprolol enantiomers using 2-hydroxypropyl-ß-cyclodextrin cross-linked multiwalled carbon nanotube.

This study investigates the ability of functionalized multiwalled carbon nanotubes (MWCNTs) for enantio-separation of metoprolol chiral forms. 2Hydroxypropyl-ß-cyclodextrin (2HP-ß-CD) was applied as a chiral selector to functionalize carbon nanotubes (CNTs). The modified multiwalled CNT samples were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. The results of analyses showed that CNTs were successfully cross-linked with 2HP-ß-CD. To evaluate the enantio-separation property of the products, the separation of metoprolol chiral forms on the initial and final products was examined. Further, UV-visible spectroscopy and polarimeter analyses were used for characterization. The results indicate that MWCNT does not have any intrinsic enantio-separation ability, although its selectivity for enantio-separation can be enhanced by cross-linking it to 2HP-ß-CD. Moreover, the optimal mass of adsorbent as well as optimal mass of functional groups is estimated to achieve maximum enantio-separation efficiency. The results indicate that applying large amounts of 2HP-ß-CD to CNTs functionalization decreases the cross-linking efficiency, which consequently reduces enantio-separation efficiency.