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Dr. أحمد التوني
King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, 11451, Saudi Arabia

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Journal article
Published: 18 May 2021 in Catalysts
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Chromium oxide supported on mesoporous organo-silica (MOS) was synthesized with different Cr loading by an incipient method. The catalytic performance of a Cr(x)/MOS catalyst for CO2-based ethane dehydrogenation was investigated. The synthesized catalysts were characterized by XRD, BET, TEM, SEM, XPS, FTIR, and UV–Vis DR measurements. The textural properties of the prepared samples showed that the mesoporous nature of MOS sample was not disturbed by chromium impregnation. Among the prepared samples, Cr(8)/MOS catalyst exhibited good distribution of chromium species along with superior concentration of Cr6+ and the highest recorded Cr6+/Cr3+ ratio. The results revealed that the superior catalytic performance was reached at Cr(8)/MOS, with 50.4% and 90.1% of ethane conversion and ethylene selectivity, respectively. The catalytic activity decreased slowly over reaction time; it declined approximately 22% after 10 h of stream operation. The roles of CO2-based ethane dehydrogenation were also studied, where carbon dioxide can be a source of lattice oxygen and as a hydrogen consumer in reverse water–gas shift (RWGS) reaction. The effect of various catalytic factors, such as catalytic temperature, reaction time, space gas velocity, and CO2 partial pressure on the conversion of ethane, yield, and selectivity to ethylene, were investigated as well.

ACS Style

Abdulrhman Al-Awadi; Ahmed El-Toni; Joselito Labis; Aslam Khan; Hamid Ghaithan; Attiyah Al-Zahrani; Ahmed Abasaeed; Saeed Al-Zahrani. Mesoporous Organo-Silica Supported Chromium Oxide Catalyst for Oxidative Dehydrogenation of Ethane to Ethylene with CO2. Catalysts 2021, 11, 642 .

AMA Style

Abdulrhman Al-Awadi, Ahmed El-Toni, Joselito Labis, Aslam Khan, Hamid Ghaithan, Attiyah Al-Zahrani, Ahmed Abasaeed, Saeed Al-Zahrani. Mesoporous Organo-Silica Supported Chromium Oxide Catalyst for Oxidative Dehydrogenation of Ethane to Ethylene with CO2. Catalysts. 2021; 11 (5):642.

Chicago/Turabian Style

Abdulrhman Al-Awadi; Ahmed El-Toni; Joselito Labis; Aslam Khan; Hamid Ghaithan; Attiyah Al-Zahrani; Ahmed Abasaeed; Saeed Al-Zahrani. 2021. "Mesoporous Organo-Silica Supported Chromium Oxide Catalyst for Oxidative Dehydrogenation of Ethane to Ethylene with CO2." Catalysts 11, no. 5: 642.

Journal article
Published: 08 March 2021 in Polymers
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In this paper, a new pH-responsive nanosystem based on mesoporous silica nanoparticles (MSNs) was developed for cancer therapy. Poly(2-(diethylamino) ethyl methacrylate) (PDEAEMA) was grafted on their outer surface and acts as a gatekeeper, followed by subsequent modification of the polymer by cysteine (MSN-PDEAEMA-Cys) and poly(oligo(ethylene glycol) methyl ether methacrylate) (MSN-PDEAEMA-Cys-POEGMEMA). The physicochemical properties of these nanocarriers were characterized using scanning and transmission electron microscopies (SEM and TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). The synthesized nanoparticles were well-dispersed with a diameter of ca. 200 nm. The obtained XPS results confirm the successful modification of MSN-PDEAEMA with Cys and POEGMEMA by increasing the peak intensity of C–O and C=O groups at 286.5 and 288.5 eV, respectively. An anti-cancer drug, doxorubicin (DOX), was encapsulated into the fabricated nanoplatform. The DOX release amount at physiological pH of 7.4 was limited (10%), while an accumulation drug release of ca. 35% was accomplished after 30 h in acidic media. The MTT cell line was used to assess the cytotoxicity of the unloaded and DOX-loaded fabricated nanoplatforms. Upon loading of DOX on these nanomaterials, they showed significant toxicity to human liver cancer cells. These results suggest that the prepared nano-structured materials showed good biocompatibility as well, and they can serve as nanocarriers for the delivery of anti-cancer drugs.

ACS Style

Khalid Alotaibi; Abdurrahman Almethen; Abeer Beagan; Latifah Alfhaid; Maqusood Ahamed; Ahmed El-Toni; Abdullah Alswieleh. Poly(oligo(ethylene glycol) methyl ether methacrylate) Capped pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Brushes Grafted on Mesoporous Silica Nanoparticles as Nanocarrier. Polymers 2021, 13, 823 .

AMA Style

Khalid Alotaibi, Abdurrahman Almethen, Abeer Beagan, Latifah Alfhaid, Maqusood Ahamed, Ahmed El-Toni, Abdullah Alswieleh. Poly(oligo(ethylene glycol) methyl ether methacrylate) Capped pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Brushes Grafted on Mesoporous Silica Nanoparticles as Nanocarrier. Polymers. 2021; 13 (5):823.

Chicago/Turabian Style

Khalid Alotaibi; Abdurrahman Almethen; Abeer Beagan; Latifah Alfhaid; Maqusood Ahamed; Ahmed El-Toni; Abdullah Alswieleh. 2021. "Poly(oligo(ethylene glycol) methyl ether methacrylate) Capped pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Brushes Grafted on Mesoporous Silica Nanoparticles as Nanocarrier." Polymers 13, no. 5: 823.

Journal article
Published: 29 October 2020 in Pharmaceutics
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Melanoma remains the most lethal form of skin cancer and most challenging to treat despite advances in the oncology field. Our work describes the utilization of nanotechnology to target melanoma locally in an attempt to provide an advanced and efficient quality of therapy. Amino-functionalized mesoporous silica nanoparticles (MSN-NH2) were developed in situ through the utilization of anionic surfactant and different volumes of 3-aminopropyltriethoxysilane (APTES) as a co-structure directing agent (CSDA). Prepared particles were characterized for their morphology, particles size, 5-flurouracol (5-FU) and dexamethasone (DEX) loading capacity and release, skin penetration, and cytotoxicity in vitro in HT-144 melanoma cells. Results of transmission electron microscopy (TEM) and nitrogen adsorption–desorption isotherm showed that using different volumes of APTES during the functionalization process had an impact on the internal and external morphology of the particles, as well as particle size. However, changing the volume of APTES did not affect the diameter of formed mesochannels, which was about 4 nm. MSN-NH2 showed a relatively high loading capacity of 5-FU (12.6 ± 5.5) and DEX (44.72 ± 4.21) when using drug: MSN-NH2 ratios of 5:1 for both drugs. The release profile showed that around 83% of 5-FU and 21% of DEX were released over 48 h in pH 7.4. The skin permeability study revealed that enhancement ratio of 5-Fu and DEX using MSN-NH2 were 4.67 and 5.68, respectively, relative to their free drugs counterparts. In addition, the accumulation of drugs in skin layers where melanoma cells usually reside were enhanced approximately 10 times with 5-FU and 5 times with DEX when delivering drugs using MSN-NH2 compared to control. MSN-NH2 alone was nontoxic to melanoma cells when incubated for 48 h in the range of 0 to 468 µg/mL. The combination of 5-FU MSN-NH2 and DEX MSN-NH2 showed significant increase in toxicity compared to their free dug counterparts and exhibited a synergetic effect as well as the ability to circumvent DEX induced 5-FU resistance in melanoma cells.

ACS Style

Aliyah Almomen; Ahmed El-Toni; Mohammed Badran; Adel Alhowyan; Mohd Abul Kalam; Aws Alshamsan; Musaed Alkholief. The Design of Anionic Surfactant-Based Amino-Functionalized Mesoporous Silica Nanoparticles and their Application in Transdermal Drug Delivery. Pharmaceutics 2020, 12, 1035 .

AMA Style

Aliyah Almomen, Ahmed El-Toni, Mohammed Badran, Adel Alhowyan, Mohd Abul Kalam, Aws Alshamsan, Musaed Alkholief. The Design of Anionic Surfactant-Based Amino-Functionalized Mesoporous Silica Nanoparticles and their Application in Transdermal Drug Delivery. Pharmaceutics. 2020; 12 (11):1035.

Chicago/Turabian Style

Aliyah Almomen; Ahmed El-Toni; Mohammed Badran; Adel Alhowyan; Mohd Abul Kalam; Aws Alshamsan; Musaed Alkholief. 2020. "The Design of Anionic Surfactant-Based Amino-Functionalized Mesoporous Silica Nanoparticles and their Application in Transdermal Drug Delivery." Pharmaceutics 12, no. 11: 1035.

Journal article
Published: 20 April 2020 in Crystals
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Ti modification of mesoporous silica support has been reported as an effective way to enhance Cr–Ti–Si interactions that, in turn, impact the catalytic dehydrogenation of ethane with CO2. However, such modification necessitates a repeated, time-consuming and tedious process. In this work, a simple, fast and facile approach has been utilized to synthesize chromium-oxide-loaded titania–silica mesoporous nanocomposites. A series of Cr(y)/Ti(x)–Si mesoporous nanocomposite catalysts with varying Ti and Cr contents were prepared and tested in the dehydrogenation of ethane with carbon dioxide. The as-synthesized catalysts were characterized by XRD, TEM, SEM, BET, UV–Vis–DR, XPS and H2–TPR techniques. The effect of titanium content, as well as chromium loading on the performance of the prepared Cr(y)/Ti(x)–Si catalysts, was investigated. It was found that 2.2 and 8 wt % are the optimum titanium and chromium contents in the synthesized catalysts for obtaining the highest catalytic activity. The superior catalytic performance of the Cr(8)/Ti(2.2)–Si catalyst can be attributed to a higher dispersion of the Cr species, as well as a higher content of the redox Cr species on the surface of the Cr/Ti–Si catalyst. The results showed that the Cr(8)/Ti(2.2)–Si catalyst efficiently dehydrogenated C2H6 in the presence of CO2 giving a 52.3% ethane conversion and 48.0% ethylene yield at 700 °C reaction temperature.

ACS Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Saeed M. Al-Zahrani; Ahmed E. Abasaeed; Aslam Khan. Synthesis, Characterization and Catalytic Evaluation of Chromium Oxide Deposited on Titania–Silica Mesoporous Nanocomposite for the Ethane Dehydrogenation with CO2. Crystals 2020, 10, 322 .

AMA Style

Abdulrhman S. Al-Awadi, Ahmed Mohamed El-Toni, Saeed M. Al-Zahrani, Ahmed E. Abasaeed, Aslam Khan. Synthesis, Characterization and Catalytic Evaluation of Chromium Oxide Deposited on Titania–Silica Mesoporous Nanocomposite for the Ethane Dehydrogenation with CO2. Crystals. 2020; 10 (4):322.

Chicago/Turabian Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Saeed M. Al-Zahrani; Ahmed E. Abasaeed; Aslam Khan. 2020. "Synthesis, Characterization and Catalytic Evaluation of Chromium Oxide Deposited on Titania–Silica Mesoporous Nanocomposite for the Ethane Dehydrogenation with CO2." Crystals 10, no. 4: 322.

Journal article
Published: 09 January 2020 in Catalysts
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A series of large-pore mesoporous silica (LPMS)-supported CrOx catalysts were synthesized by hydrothermal and impregnation methods and tested for ethane dehydrogenation in the presence of CO2 as an oxidant. To assess the effect of hydrothermal temperature treatment on the characteristics of LPMS support, different hydrothermal temperatures (100–160 °C) were studied and optimized. The optimum support was then loaded with different amounts of chromium (0, 2, 4, 8, and 11 wt % Cr). The obtained catalysts were characterized by different techniques such as XRD, BET, TEM, SEM, XPS, FTIR, and diffuse reflectance UV-Vis spectroscopy. The characterization results indicated that the sample hydrothermally treated at 130 °C exhibited the highest pore volume, a narrow pore size distribution, and a moderate BET surface area. Chromium species with various oxidation states including Cr3+, Cr6+, and α-Cr2O3 were detected in all synthesized Cr(y)/LPMS-130 catalysts. A lower Cr content resulted in the formation of Cr6+, whereas a higher Cr content dominated the α-Cr2O3 on the surface of the catalyst. Among the synthesized catalysts, the Cr(4)/LPMS-130 catalyst showed the highest Cr6+/Cr3+ ratio, indicating a good dispersion of chromium species along with a fine particle size. The ethane conversion and ethylene selectivity were 50.5 and 91.1% for Cr(4)/LPMS-130, respectively. Carbon dioxide was believed to supply enough lattice oxygen to maintain the Cr species at a higher oxidation state and to consume the hydrogen resulting from ethane cracking by a reverse water gas shift reaction.

ACS Style

Abdulrhman S. Al-Awadi; Saeed M. Al-Zahrani; Ahmed Mohamed El-Toni; Ahmed E. Abasaeed. Dehydrogenation of Ethane to Ethylene by CO2 over Highly Dispersed Cr on Large-Pore Mesoporous Silica Catalysts. Catalysts 2020, 10, 97 .

AMA Style

Abdulrhman S. Al-Awadi, Saeed M. Al-Zahrani, Ahmed Mohamed El-Toni, Ahmed E. Abasaeed. Dehydrogenation of Ethane to Ethylene by CO2 over Highly Dispersed Cr on Large-Pore Mesoporous Silica Catalysts. Catalysts. 2020; 10 (1):97.

Chicago/Turabian Style

Abdulrhman S. Al-Awadi; Saeed M. Al-Zahrani; Ahmed Mohamed El-Toni; Ahmed E. Abasaeed. 2020. "Dehydrogenation of Ethane to Ethylene by CO2 over Highly Dispersed Cr on Large-Pore Mesoporous Silica Catalysts." Catalysts 10, no. 1: 97.

Journal article
Published: 20 December 2019 in Crystals
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Oxidative dehydrogenation of alkanes to alkenes by a mild oxidant such as carbon dioxide is an active area of research. A series of MCM41-supported bimetallic oxide catalysts containing chromium oxide in addition to metal oxides (Ce, Co, Zn, V, Nb, and Mo) has been prepared. The binary catalysts have Cr metal oxide incorporated into MCM41 structure while the other oxides are either incorporated with Cr or impregnated on the MCM41 surface. The synthesized catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 sorption, scanning electron microscopy (SEM), hydrogen temperature programmed reduction (H2-TPR), and Diffuse reflectance UV–vis spectroscopy (DRS). The catalytic activity of Cr(4)-M(4)/MCM-41 catalysts in the dehydrogenation of ethane with CO2 was investigated. The textural properties of the synthesized samples showed that the addition of the bimetallic oxides did not disturb the mesoporous structure of MCM41 and the prepared catalysts exhibited a high BET surface area; however, the lowest surface area was recorded for Cr(4)-Mo(4)/MCM41 catalyst at 701 m2/g. Among the prepared catalysts, H2-TPR profile of Cr(4)-Ce(4)/MCM41 revealed the increase in the concentration of Cr6+ species which interacted with the framework of siliceous support. On the other hand, H2-TPR profiles of Cr(4)-Co(4)/MCM41 showed wide reduction peaks centered at 400 °C which is ascribed to reduction of Cr6+ to Cr3+ species and Co3O4 to metallic Co. At the same time, Cr(4)-Mo(4)/MCM41 and Cr(4)-V(4)/MCM41 exhibited higher temperature reduction peaks, indicating these two catalysts require higher activation temperatures. The synergy between the Cr with Zn or Nb metals reduced the concentration of Cr6+ species which is reflected in their catalytic performance. Cr(4)-Ce(4)/MCM41 recorded the highest catalytic activity toward ethylene production where the ethane conversion and ethylene yield were 37.9% and 35.1%, respectively.

ACS Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Mansour Alhoshan; Aslam Khan; Muhammad Ali Shar; Ahmed E. Abasaeed; Saeed M. Al-Zahrani. Synergetic Impact of Secondary Metal Oxides of Cr-M/MCM41 Catalyst Nanoparticles for Ethane Oxidative Dehydrogenation Using Carbon Dioxide. Crystals 2019, 10, 7 .

AMA Style

Abdulrhman S. Al-Awadi, Ahmed Mohamed El-Toni, Mansour Alhoshan, Aslam Khan, Muhammad Ali Shar, Ahmed E. Abasaeed, Saeed M. Al-Zahrani. Synergetic Impact of Secondary Metal Oxides of Cr-M/MCM41 Catalyst Nanoparticles for Ethane Oxidative Dehydrogenation Using Carbon Dioxide. Crystals. 2019; 10 (1):7.

Chicago/Turabian Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Mansour Alhoshan; Aslam Khan; Muhammad Ali Shar; Ahmed E. Abasaeed; Saeed M. Al-Zahrani. 2019. "Synergetic Impact of Secondary Metal Oxides of Cr-M/MCM41 Catalyst Nanoparticles for Ethane Oxidative Dehydrogenation Using Carbon Dioxide." Crystals 10, no. 1: 7.

Journal article
Published: 10 May 2019 in Applied Sciences
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Ni, Co, and Co–Ni bimetallic catalysts supported over SBA-15 and over SBA-15 doped with Zn or Ce oxides were prepared and tested in a methane dry reforming reaction. The loading of the metals in the catalyst was 5 wt % for either mono or bimetallic catalysts. The prepared catalysts were tested in a continuous-flow fixed-bed reactor at 800 °C under atmospheric pressure. XRD, TPR, TPD, and SEM characterization techniques were employed to investigate the catalytic properties of fresh catalysts. SEM and TGA were used to study the catalytic properties of spent catalysts. A remarkable effect on the reduction properties and catalytic performance of catalysts was observed after adding Zn and Ce. Over an 8 h test, Ni/SBA-15 showed the best activity and stability. The conversion was 90% for CH4 and CO2. Co–Ni/SBA-15 and Co–Ni/Ce–SBA-15 have shown a reasonable activity and stability. Selectivity of the Ni/SBA-15 catalyst was higher than all other catalysts as indicated by the H2/CO ratio. Co/SBA-15 and Co–Ni/Zn–SBA-15 showed a low activity and selectivity. TPD–NH3 profiles indicated that doping SBA-15 with Ce and/or Zn increased the catalyst acidic sites. Ni/SBA-15 is an excellent potential catalyst for commercial methane dry reforming processes.

ACS Style

Ahmed A. Ibrahim; Ashraf Amin; Ahmed S. Al-Fatesh; Nadavala Siva Kumar; Samsudeen Olajide Kasim; Abdulrhman S. Al-Awadi; Ahmed M. El-Toni; Ahmed Elhag Abasaeed; Anis H. Fakeeha. Nanosized Ni/SBA-15 Catalysts for CO2 Reforming of CH4. Applied Sciences 2019, 9, 1926 .

AMA Style

Ahmed A. Ibrahim, Ashraf Amin, Ahmed S. Al-Fatesh, Nadavala Siva Kumar, Samsudeen Olajide Kasim, Abdulrhman S. Al-Awadi, Ahmed M. El-Toni, Ahmed Elhag Abasaeed, Anis H. Fakeeha. Nanosized Ni/SBA-15 Catalysts for CO2 Reforming of CH4. Applied Sciences. 2019; 9 (9):1926.

Chicago/Turabian Style

Ahmed A. Ibrahim; Ashraf Amin; Ahmed S. Al-Fatesh; Nadavala Siva Kumar; Samsudeen Olajide Kasim; Abdulrhman S. Al-Awadi; Ahmed M. El-Toni; Ahmed Elhag Abasaeed; Anis H. Fakeeha. 2019. "Nanosized Ni/SBA-15 Catalysts for CO2 Reforming of CH4." Applied Sciences 9, no. 9: 1926.

Article
Published: 19 December 2018 in Journal of the American Ceramic Society
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In this study, pulsed laser ablation technique, also known as pulsed laser deposition (PLD), is used to design and grow ZnO nanostructures (nanoworms, nanowalls, and nanorods) by template/seeding approach for gas‐sensing applications. Conventionally, ZnO nanostructures used for gas sensing have been usually prepared via chemical route, where the 3D/2D nanostructures are chemically synthesized and subsequently plated on an appropriate substrate. However, using pulsed laser ablation technique, the ZnO nanostructures are structurally designed and grown directly on a substrate using a two‐step temperature‐pressure seeding approach. This approach has been optimized to design various ZnO nanostructures by understanding the effect of substrate temperature in the 300 ‐ 750°C range under O2 gas pressure from 10‐milli to 10 Torr. Using a thin ZnO seed layer as template that is deposited first at substrate temperature of ~300°C at background oxygen pressure of 10 mTorr on Si(100), ZnO nanostructures, such as nanoworms, nanowalls, and nanorods (with secondary flower‐like growth) were grown at substrate temperatures and oxygen background pressures of (550°C and 2 Torr), (550°C and 0.5 Torr) and (650°C and 2 Torr), respectively. The morphology and the optical properties of ZnO nanostructures were examined by Scanning Electron Microscope (SEM‐EDX), X‐ray Diffraction (XRD), and Photoluminescence (PL). The PLD‐grown ZnO nanostructures are single‐crystals and are highly‐oriented in the c‐axis. The vapor‐solid (VS) model is proposed to be responsible for the growth of ZnO nanostructures by PLD process. Further, the ZnO nanowall structure is a very promising nanostructure due to its very high surface‐to‐volume ratio. Although ZnO nanowalls have been grown by other methods for sensor application, to this date, only a very few ZnO nanowalls have been grown by PLD for this purpose. In this regard, ZnO nanowall structures are deposited by PLD on an Al2O3 test sensor and assessed for their responses to CO and ethanol gases at 50 ppm, where good responses were observed respectively at 350 and 400 °C. The PLD‐grown ZnO nanostructures are very excellent materials for potential applications such as in dye‐sensitized solar cells, perovskite solar cells and biological and gas sensors. This article is protected by copyright. All rights reserved.

ACS Style

Joselito P. Labis; Anwar Q. Al‐Anazi; Hamad A. Al‐Brithen; Mahmoud Hezam; Mohammad AbdulAziz Alduraibi; Ahmad Al‐Garni; Abdulaziz A. Al‐Harbi; Abdulrhman S. Al‐Awadi; Aslam Khan; Ahmed Mohamed El‐Toni. Designing zinc oxide nanostructures (nanoworms, nanoflowers, nanowalls, and nanorods) by pulsed laser ablation technique for gas‐sensing application. Journal of the American Ceramic Society 2018, 102, 4367 -4375.

AMA Style

Joselito P. Labis, Anwar Q. Al‐Anazi, Hamad A. Al‐Brithen, Mahmoud Hezam, Mohammad AbdulAziz Alduraibi, Ahmad Al‐Garni, Abdulaziz A. Al‐Harbi, Abdulrhman S. Al‐Awadi, Aslam Khan, Ahmed Mohamed El‐Toni. Designing zinc oxide nanostructures (nanoworms, nanoflowers, nanowalls, and nanorods) by pulsed laser ablation technique for gas‐sensing application. Journal of the American Ceramic Society. 2018; 102 (7):4367-4375.

Chicago/Turabian Style

Joselito P. Labis; Anwar Q. Al‐Anazi; Hamad A. Al‐Brithen; Mahmoud Hezam; Mohammad AbdulAziz Alduraibi; Ahmad Al‐Garni; Abdulaziz A. Al‐Harbi; Abdulrhman S. Al‐Awadi; Aslam Khan; Ahmed Mohamed El‐Toni. 2018. "Designing zinc oxide nanostructures (nanoworms, nanoflowers, nanowalls, and nanorods) by pulsed laser ablation technique for gas‐sensing application." Journal of the American Ceramic Society 102, no. 7: 4367-4375.

Journal article
Published: 03 October 2018 in Ceramics International
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In this work, the effect of sequence addition of silica and chromium precursors of one-pot synthesis of Cr/MCM-41catalysts on their structural properties and catalytic performance for oxidative dehydrogenation of ethane (ODH) to ethylene using CO2 was investigated. The developed catalysts have been characterized by several techniques such as N2 sorption analyzer, XRD, TEM, SEM, UV-Vis, FTIR, TPD, and XPS. Results showed that the pore and surface characteristics of the developed catalysts strongly depend on the employed sequence. Catalyst prepared by sequence of addition of tetraethyl orthosilicate (TEOS) then Cr, exhibited similar catalytic property to the one prepared using conventional impregnation method. On the other hand, prepared catalyst with sequence of Cr then TEOS, exhibited the highest catalytic ethylene conversion and yield ~ 58 and 53%, respectively at 700 oC. The enhanced performance arose from the small sizes of mesoporous silica nanoparticles that promoted the high degree of dispersion for CrOx species into meso-channels and surface of porous silica support. Moreover, those small sizes of mesoporous silica nanoparticles have enhanced the interaction of reactants with CrOx species, thus facilitating a faster reduction-oxidation cycle. Various chromium species including Cr6+, Cr3+ and crystalline Cr2O3 were found in all prepared samples; however the highest Cr6+/Cr3+ ratio, that reportedly to be highly active one, was recorded for 8 wt%Cr/MCM-41-Cr-TEOS catalyst. Furthermore, the impact of different Cr loading contents based on Cr-TEOS sequence of addition on the conversion of ethane, yield and selectivity to ethylene has been investigated as well.

ACS Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Mansour Alhoshan; Aslam Khan; Joselito P. Labis; Ahmed Alfatesh; Ahmed E. Abasaeed; Saeed M. Al-Zahrani. Impact of precursor sequence of addition for one-pot synthesis of Cr-MCM-41 catalyst nanoparticles to enhance ethane oxidative dehydrogenation with carbon dioxide. Ceramics International 2018, 45, 1125 -1134.

AMA Style

Abdulrhman S. Al-Awadi, Ahmed Mohamed El-Toni, Mansour Alhoshan, Aslam Khan, Joselito P. Labis, Ahmed Alfatesh, Ahmed E. Abasaeed, Saeed M. Al-Zahrani. Impact of precursor sequence of addition for one-pot synthesis of Cr-MCM-41 catalyst nanoparticles to enhance ethane oxidative dehydrogenation with carbon dioxide. Ceramics International. 2018; 45 (1):1125-1134.

Chicago/Turabian Style

Abdulrhman S. Al-Awadi; Ahmed Mohamed El-Toni; Mansour Alhoshan; Aslam Khan; Joselito P. Labis; Ahmed Alfatesh; Ahmed E. Abasaeed; Saeed M. Al-Zahrani. 2018. "Impact of precursor sequence of addition for one-pot synthesis of Cr-MCM-41 catalyst nanoparticles to enhance ethane oxidative dehydrogenation with carbon dioxide." Ceramics International 45, no. 1: 1125-1134.

Journal article
Published: 01 June 2018 in Catalysts
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The stability and catalytic activity of mesoporous Ni/MCM-41 promoted with a Ga loading of (0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 wt %) as an innovative catalyst was examined for syngas production via CO2 reforming of CH4. The objective of present work was to develop a potential catalyst for CO2 reforming of methane. For this purpose different loadings of gallium were used to promote 5% nickel catalyst supported on MCM-41. An incipient wetness impregnation method was used for preparing the catalysts and investigated at 800 °C. Physicochemical characterization techniques—including BET, XRD, TPD, TPR, TEM, and TGA—were used to characterize the catalysts. The addition of small amounts of Ga resulted in higher surface areas with a maximum surface area of 1036 m2/g for 2.5% Ga. The incorporation of Ga to the catalyst decreased the medium and strong basic sites and reduced the amount of carbon deposited. There was no weight loss for 3%Ga+5%Ni/MCM-41. The 2% Ga loading showed the highest CH4 conversion of 88.2% and optimum stability, with an activity loss of only 1.58%. The Ga promoter raised the H2/CO ratio from 0.9 to unity.

ACS Style

Ahmed S. Al-Fatesh; Ahmed A. Ibrahim; Jehad K. Abu-Dahrieh; Abdulrahman S. Al-Awadi; Ahmed Mohamed El-Toni; Anis H. Fakeeha; Ahmed E. Abasaeed. Gallium-Promoted Ni Catalyst Supported on MCM-41 for Dry Reforming of Methane. Catalysts 2018, 8, 229 .

AMA Style

Ahmed S. Al-Fatesh, Ahmed A. Ibrahim, Jehad K. Abu-Dahrieh, Abdulrahman S. Al-Awadi, Ahmed Mohamed El-Toni, Anis H. Fakeeha, Ahmed E. Abasaeed. Gallium-Promoted Ni Catalyst Supported on MCM-41 for Dry Reforming of Methane. Catalysts. 2018; 8 (6):229.

Chicago/Turabian Style

Ahmed S. Al-Fatesh; Ahmed A. Ibrahim; Jehad K. Abu-Dahrieh; Abdulrahman S. Al-Awadi; Ahmed Mohamed El-Toni; Anis H. Fakeeha; Ahmed E. Abasaeed. 2018. "Gallium-Promoted Ni Catalyst Supported on MCM-41 for Dry Reforming of Methane." Catalysts 8, no. 6: 229.

Journal article
Published: 27 November 2017 in Molecules
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Magnetic nanoparticles are used in adsorptive removal of heavy metals from polluted wastewater. However, their poor stability in an acidic medium necessitates their protection with a coating layer. Coating magnetic nanoparticles with carbon showed proper protection but the heavy metal removal efficiency was slightly weak. However, to boost the removal efficiencies of surface functionalization, polyacrylamide was applied to carbon-coated Fe3O4 nanoparticles. In this paper, to facilitate the synthesis process, one-step carbon coating and polyacrylamide functionalization were conducted using the hydrothermal technique with the aim of enhancing the adsorptive removal capacity of Fe3O4 nanoparticles towards some heavy metals such as Cu(II), Ni(II), Co(II), and Cd(II). The results showed that the one-step process succeeded in developing a carbon coating layer and polyacrylamide functionality on Fe3O4 nanoparticles. The stability of the magnetic Fe3O4 nanoparticles as an adsorbent in an acidic medium was improved due to its resistance to the dissolution that was gained during carbon coating and surface functionalization with polyacrylamide. The adsorptive removal process was investigated in relation to various parameters such as pH, time of contact, metal ion concentrations, adsorbent dose, and temperature. The polyacrylamide functionalized Fe3O4 showed an improvement in the adsorption capacity as compared with the unfunctionalized one. The conditions for superior adsorption were obtained at pH 6; time of contact, 90 min; metal solution concentration, 200 mg/L; adsorbent dose, 0.3 g/L. The modeling of the adsorption data was found to be consistent with the pseudo-second-order kinetic model, which suggests a fast adsorption process. However, the equilibrium data modeling was consistent with both the Langmuir and Freundlich isotherms. Furthermore, the thermodynamic parameters of the adsorptive removal process, including ΔG°, ΔH°, and ΔS°, indicated a spontaneous and endothermic sorption process. The developed adsorbent can be utilized further for industrial-based applications.

ACS Style

Mohamed A. Habila; Zeid A. Alothman; Ahmed Mohamed El-Toni; Joselito Puzon Labis; Aslam Khan; Adel Al-Marghany; Hussein Elsayed Elafifi. One-Step Carbon Coating and Polyacrylamide Functionalization of Fe3O4 Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals. Molecules 2017, 22, 2074 .

AMA Style

Mohamed A. Habila, Zeid A. Alothman, Ahmed Mohamed El-Toni, Joselito Puzon Labis, Aslam Khan, Adel Al-Marghany, Hussein Elsayed Elafifi. One-Step Carbon Coating and Polyacrylamide Functionalization of Fe3O4 Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals. Molecules. 2017; 22 (12):2074.

Chicago/Turabian Style

Mohamed A. Habila; Zeid A. Alothman; Ahmed Mohamed El-Toni; Joselito Puzon Labis; Aslam Khan; Adel Al-Marghany; Hussein Elsayed Elafifi. 2017. "One-Step Carbon Coating and Polyacrylamide Functionalization of Fe3O4 Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals." Molecules 22, no. 12: 2074.

Journal article
Published: 29 January 2016 in International Journal of Molecular Sciences
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The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS) nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS–NH2 nanospheres showed highest immobilization yield (75.6%) and loading capacity (88.1 μg protein/mg carrier) and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher Vmax, kcat and kcat/Km, than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.

ACS Style

Abdelnasser Salah Shebl Ibrahim; Ali A. Al-Salamah; Ahmed M. El-Toni; Khalid S. Almaary; Mohamed A. El-Tayeb; Yahya B. Elbadawi; Garabed Antranikian. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres. International Journal of Molecular Sciences 2016, 17, 184 .

AMA Style

Abdelnasser Salah Shebl Ibrahim, Ali A. Al-Salamah, Ahmed M. El-Toni, Khalid S. Almaary, Mohamed A. El-Tayeb, Yahya B. Elbadawi, Garabed Antranikian. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres. International Journal of Molecular Sciences. 2016; 17 (2):184.

Chicago/Turabian Style

Abdelnasser Salah Shebl Ibrahim; Ali A. Al-Salamah; Ahmed M. El-Toni; Khalid S. Almaary; Mohamed A. El-Tayeb; Yahya B. Elbadawi; Garabed Antranikian. 2016. "Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres." International Journal of Molecular Sciences 17, no. 2: 184.

Journal article
Published: 30 May 2013 in International Journal of Molecular Sciences
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In this work, [email protected] nanoparticles were coated with mesoporous silica shell by S−N+I− pathway by using anionic surfactant (S−) and co-structure directing agent (N+). The role of co-structure directing agent (CSDA) is to assist the electrostatic interaction between negatively charged silica layers and the negatively charged surfactant molecules. Prior to the mesoporous shell formation step, magnetic cores were coated with a dense silica layer to prevent iron oxide cores from leaching into the mother system under any acidic circumstances. However, it was found that both dense and mesoporous coating parameters affect the textural properties of the produced mesoporous silica shell (i.e., surface area, pore volume and shell thickness). The synthesized [email protected]@m-SiO2 (MCMSS) nanoparticles have been characterized by low-angle X-ray diffraction, transmission electron microscopy (TEM), and N2 adsorption-desorption analysis, and magnetic properties. The synthesized particles had dense and mesoporous silica shells of 8–37 nm and 26–50 nm, respectively. Furthermore, MCMSS possessed surface area of ca. 259–621 m2·g−1, and pore volume of ca. 0.216–0.443 cc·g−1. MCMSS showed docetaxcel cancer drug storage capacity of 25–33 w/w% and possessed control release from their mesochannels which suggest them as proper nanocarriers for docetaxcel molecules.

ACS Style

Ahmed Mohamed El-Toni; Mohamed Abbas Ibrahim; Joselito Puzon Labis; Aslam Khan; Mansour Alhoshan. Optimization of Synthesis Parameters for Mesoporous Shell Formation on Magnetic Nanocores and Their Application as Nanocarriers for Docetaxel Cancer Drug. International Journal of Molecular Sciences 2013, 14, 11496 -11509.

AMA Style

Ahmed Mohamed El-Toni, Mohamed Abbas Ibrahim, Joselito Puzon Labis, Aslam Khan, Mansour Alhoshan. Optimization of Synthesis Parameters for Mesoporous Shell Formation on Magnetic Nanocores and Their Application as Nanocarriers for Docetaxel Cancer Drug. International Journal of Molecular Sciences. 2013; 14 (6):11496-11509.

Chicago/Turabian Style

Ahmed Mohamed El-Toni; Mohamed Abbas Ibrahim; Joselito Puzon Labis; Aslam Khan; Mansour Alhoshan. 2013. "Optimization of Synthesis Parameters for Mesoporous Shell Formation on Magnetic Nanocores and Their Application as Nanocarriers for Docetaxel Cancer Drug." International Journal of Molecular Sciences 14, no. 6: 11496-11509.

Journal article
Published: 06 November 2012 in Molecules
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In this work, mesoporous shells were constructed on solid silica cores by employing anionic surfactante. A co-structure directing agent (CSDA) has assisted the electrostatic interaction between negatively charged silica particles and the negatively charged surfactant molecules. Synthetic parameters such as reaction time and temperature had a significant impact on the formation of mesoporous silica shelld and their textural properties such as surface area and pore volume. Core-mesoporous shell silica spheres were characterized by small angle X-ray scattering, transmission electron microscopy, and N2 adsorption–desorption analysis. The synthesized particles have a uniformly mesoporous shell of 34–65 nm and possess a surface area of ca. 7–324 m2/g, and pore volume of ca. 0.008–0.261 cc/g. The core-mesoporous shell silica spheres were loaded with ketoprofen drug molecules. The in vitro drug release study suggested that core-mesoporous shell silica spheres are a suitable nanocarrier for drug molecules offering the possibility of having control over their release rate.

ACS Style

Ahmed Mohamed El-Toni; Aslam Khan; Mohamed Abbas Ibrahim; Mansour Al-Hoshan; Joselito Puzon Labis. Fabrication of Mesoporous Silica Shells on Solid Silica Spheres Using Anionic Surfactants and Their Potential Application in Controlling Drug Release. Molecules 2012, 17, 13199 -13210.

AMA Style

Ahmed Mohamed El-Toni, Aslam Khan, Mohamed Abbas Ibrahim, Mansour Al-Hoshan, Joselito Puzon Labis. Fabrication of Mesoporous Silica Shells on Solid Silica Spheres Using Anionic Surfactants and Their Potential Application in Controlling Drug Release. Molecules. 2012; 17 (11):13199-13210.

Chicago/Turabian Style

Ahmed Mohamed El-Toni; Aslam Khan; Mohamed Abbas Ibrahim; Mansour Al-Hoshan; Joselito Puzon Labis. 2012. "Fabrication of Mesoporous Silica Shells on Solid Silica Spheres Using Anionic Surfactants and Their Potential Application in Controlling Drug Release." Molecules 17, no. 11: 13199-13210.

Journal article
Published: 17 April 2012 in Journal of Colloid and Interface Science
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In this work, we demonstrate a simple two-pot approach to double mesoporous core–shell silica spheres (DMCSSs) with uniform size of 245–790 nm, shell thickness of 41–80 nm and surface area and total pore volume of 141–618 m2 g−1 and 0.14–0.585 cc g−1, respectively. First, solid silica spherical particles were synthesized by the Stöber method and used as a core. Second, a mesoporous shell could be formed around the silica cores by using an anionic surfactant and a co-structure directing agent. It was found that mesopores can be anchored within dense silica cores during mesoporous silica shell formation, synchronously the base group with surfactant assistant can etch the dense silica cores to re-organize new mesostructure, so that double mesoporous core–shell silica sphere (DMCSS) structure can be obtained by a single surfactant-templating step. The spherical size and porosity of the silica cores of DMCSS together with shell thickness can be tuned by controlling Stöber parameters, including the concentrations of ammonia, solvent and tetraethoxysilane and the reaction time. DMCSS were loaded with ketoprofen and thymoquinone, which are an anti-inflammatory and a potential novel anti-cancer drug, respectively. Both drugs showed controlled release behavior from the pores of DMCSS. Drug uptakes within DMCSS were ∼27 and 81 wt.% for ketoprofen and thymoquinone, respectively. Furthermore, DMCSS loaded with thymoquinone was more effective in inducing cancer cell apoptosis than uncontained thymoquinone, because of the slow release of the drug from the mesoporous structure.

ACS Style

Ahmed Mohamed El-Toni; Aslam Khan; Mohamed Abbas Ibrahim; Joselito Puzon Labis; Gamal Badr; Mansour Al-Hoshan; Shu Yin; Tsugio Sato. Synthesis of double mesoporous core–shell silica spheres with tunable core porosity and their drug release and cancer cell apoptosis properties. Journal of Colloid and Interface Science 2012, 378, 83 -92.

AMA Style

Ahmed Mohamed El-Toni, Aslam Khan, Mohamed Abbas Ibrahim, Joselito Puzon Labis, Gamal Badr, Mansour Al-Hoshan, Shu Yin, Tsugio Sato. Synthesis of double mesoporous core–shell silica spheres with tunable core porosity and their drug release and cancer cell apoptosis properties. Journal of Colloid and Interface Science. 2012; 378 (1):83-92.

Chicago/Turabian Style

Ahmed Mohamed El-Toni; Aslam Khan; Mohamed Abbas Ibrahim; Joselito Puzon Labis; Gamal Badr; Mansour Al-Hoshan; Shu Yin; Tsugio Sato. 2012. "Synthesis of double mesoporous core–shell silica spheres with tunable core porosity and their drug release and cancer cell apoptosis properties." Journal of Colloid and Interface Science 378, no. 1: 83-92.

Correspondence
Published: 15 October 2010 in Journal of Alloys and Compounds
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Due to its excellent UV-rays shielding properties, titanium dioxide can be used in many sunscreen products. However, concerns have been raised about the possible photocatalytic decomposition of cosmetic formulation by titanium dioxide. Therefore, titania nanoparticles were encapsulated in silica shell by using solvothermal process. Both temperature and time parameters of the solvothermal process were optimized to produce silica shell with highest density (loss of micropores) and maximum shell thickness. The coated particles were characterized by X-ray diffraction (XRD), TEM, FTIR, XPS, zeta-potential, and porosity measurements. The photocatalytic activity of the coated samples was suppressed effectively by conducting solvothermal silica coating at 200 °C for 15 h where TEM observations revealed the gradual growth of silica shell around TiO2 nanoparticles. On the other hand, UV-shielding properties were slightly reduced after silica coating which can be attributed to the loss of titania content.

ACS Style

Ahmed Mohamed El-Toni; Shu Yin; Tsugio Sato; Talal Ghannam; Mansour Al-Hoshan; Mohamed Al-Salhi. Investigation of photocatalytic activity and UV-shielding properties for silica coated titania nanoparticles by solvothermal coating. Journal of Alloys and Compounds 2010, 508, L1 -L4.

AMA Style

Ahmed Mohamed El-Toni, Shu Yin, Tsugio Sato, Talal Ghannam, Mansour Al-Hoshan, Mohamed Al-Salhi. Investigation of photocatalytic activity and UV-shielding properties for silica coated titania nanoparticles by solvothermal coating. Journal of Alloys and Compounds. 2010; 508 (1):L1-L4.

Chicago/Turabian Style

Ahmed Mohamed El-Toni; Shu Yin; Tsugio Sato; Talal Ghannam; Mansour Al-Hoshan; Mohamed Al-Salhi. 2010. "Investigation of photocatalytic activity and UV-shielding properties for silica coated titania nanoparticles by solvothermal coating." Journal of Alloys and Compounds 508, no. 1: L1-L4.