Sameh Osman

King Saud University | KKUH · Department of Chemistry

Fuel cell technologies constitute a clean, reliable, highly efficient, and eco‐friendly source of alternative energy generation. However, they still require a reliable and robust catalytic system showing comparative electrochemical activity to precious metal Pt with less cost. In this work, Mn@ZnO NPs were synthesized using a hydrothermal‐assisted...

Maximizing the utilization efficiency of monatomic Fe sites in Fe–N–C catalysts poses a significant challenge for their commercial applications. Herein, a structural and electronic dual-modulation is achieved on a Fe–N–C catalyst to substantially enhance its catalytic performance. We develop a facile multi-component ice-templating co-assembly (MIC)...

Nitrogen doped leather waste-derived carbon materials have been employed as eletrocatalyst for oxygen evo�lution reaction. Low current densities and complex synthesis routes of other carbon-based materials limit their practical applicability. We present herein a simple and cost-competitive design of a metal free nitrogen-doped carbon matrix (NCM)....

The production of vanillin from biomass offers a sustainable route for synthesizing daily-use chemicals. However, achieving sunlight-driven vanillin synthesis through H 2 O activation in an aqueous environment poses challenges due to the high barrier of H 2 O dissociation. In this study, we have successfully developed an efficient approach for gram...

Although hollow carbon structures have been extensively studied in recent years, their interior surfaces are not fully utilized due to the lack of fluent porous channels in the closed shell walls. This study presents a tailored design of open‐mouthed particles hollow cobalt/nitrogen‐doped carbon with mesoporous shells (OMH‐Co/NC), which exhibits su...

Diffusion dialysis (DD) process utilizing anion exchange membranes (AEMs) is an environmentally-friendly and energy-efficient technology. From acidic wastewater, DD is needed for acid recovery. This research reports the development of a series of dense tropinium-functionalized AEMs via solution casting method. Fourier Infrared transform (FTIR) spec...

The exploitation of biomass to reduce the dependency on fossil fuels represents a challenge that needs to be solved as soon as possible. Nowadays, one of the most fashionable processes is γ‐valerolactone (GVL) production from bio‐derived methyl levulinate (ML). Deep understanding of the thermodynamic aspects involved in this process is key for a su...

A TiO2-Fe2O3/C catalyst was synthesized utilizing Metal-Organic-Frameworks (MOFs) as a sacrificial template prepared by the solvothermal method and pyrolyzed in an inert nitrogen (N2) atmosphere. This material was characterized using various techniques, including X-ray diffraction, N2 porosimetry, and X-ray photoelectron spectroscopy; these techniq...

Mesoporous materials Al-SBA-15 have been synthesized and functionalized with different Al/Zr molar ratio and 0.5% Au and Ru, respectively, by a mechanochemical approach. Textural and structural properties of synthesized materials have been analysed by TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy), XPS (X-ray photoelectr...

A potential application of spiky SiO2 nanoparticles (NPs) with tubular and rough surfaces is investigated as superhydrophobic coatings, for their unique transparent, fluorinate‐free, and environmentally friendly properties. This study demonstrates a facile method for the successful fabrication of superhydrophobic coatings and SiO2@polydimethylsilox...

The acetalization of furfural and ethanol was investigated over aluminophosphate (APAl) catalysts using both batch and flow reaction systems to produce furfural diethyl acetal (FDA). APAl catalysts were synthesized with varying P/Al ratios and calcination temperatures to study their effects on Brønsted acid active sites for the reaction. Catalysts...

Microwave (MW) and conventional heating (CH) strategies were compared for the synthesis of fuel additives (alkyl levulinates) obtained from levulinic acid. Phosphomolybdic acid (PMA) and phosphotungstic acid (PTA)-containing graphitic carbon...

The rapid industrialization of the world is disparagingly manipulating our environment and natural ecosystem. The researchers are taking keen interest to invent novel material as photocatalyst for non-degradable organic pollutants. Solar energy-driven practices employing semiconductors are a novel approach towards wastewater remediation. Here in, w...

Conventional chemotherapy poses toxic effects to healthy tissues. A therapeutic system is thus required that can administer, distribute, metabolize, and excrete medicine from human body without damaging healthy cells. This is possible by designing a therapeutic system that can release drug at specific target tissue. In current work, novel chitosan...

The rational fabrication of Pt‐free catalysts for driving the development of practical applications in alkaline water electrolysis and fuel cells is promising but challenging. Herein, a promising approach is outlined for the rational design of multimetallic catalysts comprising multiple active sites including Pd nanoclusters and Ru single atoms anc...

Fatty Acid Ethyl Esters (FAEEs) were obtained via single-step esterification of non-edible raw materials, namely a distillate from the deodorization of palm oil (DDPO), an agro-industrial by-product of high concentration of free fatty acids (FFAs approximately 84%) with Ethanol (EtOH) over a solid acid catalyst MF4W15 prepared from Amazon flint kao...

Nanomaterials mainly nanocomposites possess unique physical and chemical properties which makes them superior and indispensable. Though much research has been focused on the properties and application of nanocomposites, the eco-toxicity assessment is one among top priority, which aims to protect the population of concerned biological component and...

The design of conductive, improved durable and selective anion exchange membranes (AEMs) for desalination application via electrodialysis (ED) process is critical for a more sustainable future. This work reports the design of a series of homogeneous trimethylphosphine (TMP)-functionalized anion exchange membranes (AEMs) for desalination application...

P-type semiconductor SrZr0.1Mn0.4Mo0.4Y0.1O3-δ (SZMMY) is for the first time composited with n-type ZnO to prepare a solid oxide electrolyte used in fuel cell operable at low temperature. Prepared nanocomposite electrolyte material is considered as a novel material owing to the results obtained in terms of improved ionic conductivity, power density...

The use of a mesoporous catalyst, (3)SO3H/AlSiM, synthesized from Amazon flint kaolin (FK), a by-product disposed of in commercial kaolin extraction mining, in the esterification of distillate from the deodorization of palm oil (DDPO), a by-product with a high free fatty acid (FFA) content (84%), from the palm oil refining industry is disclosed her...

A covalent organic framework (COF) was used as the support of the catalyst in this work in order to obtain an environmentally friendly catalyst with high catalytic performance, selectivity and stability for 4-nitrophenol hydrogenation. Pd tiny particles are fixed in the cavity of COF to obtain Pd/COF catalysts, which has a quite narrow particle siz...

The reductive amination reaction of furfural with acetonitrile has been explored employing various catalytic systems based on supported Rh, Ru, Pt and Pd nanoparticles. The synthesis of Rh and Ru nanoparticles supported on titania was accomplished following an environmentally friendly two step-protocol, based on the microwave assisted preparation o...

Highly active, selective and stable titania-based catalytic materials have been designed through a simple and environmentally friendly microwave-assisted approach. Further modification of the prepared titania with metal nanoparticles was carried out by a simple chemical reduction method. The synthesized materials displayed excellent catalytic behav...

Multi-step organic syntheses of various drugs, active pharmaceutical ingredients, other pharmaceutically and agriculturally important compounds have already been reported using flow synthesis. Compared to batch, hazardous and reactive reagents can be handled safely in flow. This review discusses the pros and cons of flow chemistry in today’s scenar...

Glycerol and aminophenol intermolecular condensation has been investigated through a milling and microwave-assisted sequential strategy, towards the synthesis of a benzoxaxine derivative. Mechanochemical activation prior to the microwave-assisted process could improve the probability of contact between the reagents, and greatly favors the higher co...

Co3O4 was synthesized in the presence of 3D porous nanostructured SiO2/carbon composite derived from rice husk via a hydrothermal method to produce Co3O4@SiO2/C nanostructures with good microstructural, morphological and excelling catalytic properties. The morphology and textural properties of the products were tuned by using different amounts of h...

The interest in the removal of emerging contaminants has increased in the last decade. Photocatalytic degradation using p-n heterojunctions could effectively provide the degradation of these type of substances that are persistent in the environment. In this work, the synthesis, characterization, and photocatalytic evaluation of TiO2–F as well as Cu...

The first structural analysis comparing the binding mode to the target carbonic anhydrases (CAs, EC 4.2.1.1) of two opposite classes of modulators is presented here: coumarin derivatives act as prodrug CA inhibitors (CAIs), being hydrolyzed by the enzyme esterase activity to 2-hydroxycinnamic acids that occlude the active site entrance; CA activato...

A series of copolymers based on s-triazine and ethylene diamine moiety were synthesized; the prepared copolymers were characterized by FT-IR, TGA, DSC, and GPC. The thermogravimetric analysis of and the thermal stability of the copolymers were used to investigate their non-isothermal behavior. The comparative kinetic study was done using Kissinger...

We herein report a design and synthesis of new 1,3,5-triazine based pyrazole derivatives (5a-i) for anticancer activity targeting epidermal growth factor (EGFR) tyrosine kinase. The newly synthesized compounds were characterized...

A series of (tartrate-salen)Mn(III) polymer complexes were prepared and immobilized into SBA-15, being subsequently employed as catalysts in the asymmetric epoxidation of alkenes. ¹H NMR, FT-IR, UV–vis, elemental analysis, GPC and ICP-AES demonstrated the successful synthesis of polymer complexes, while powdered XRD, nitrogen physisorption and XPS...

A series of oligomeric (salen)Mn(III) complexes featuring tartrate linkers were prepared and immobilized over layered double hydroxide, and then used as catalysts for asymmetric epoxidation of unfunctionalized olefins. Comprehensive characterizations including 1H NMR, FT-IR, UV-Vis, elemental analysis, GPC, and ICP-AES were used to illustrate struc...

Herein, we described the modification of chitosan with cyanuric chloride as a mediator for preparation of chitosan-s-triazinyl-bis(2-aminomethylpyridine) and chitosan-s-triazinyl-bis(8-oxyquinoline) derivatives to be used as reagents for preparation of silver nanoparticles under ecofriendly conditions. These two reagents are convenient and effectiv...

Human carbonic anhydrase (CA; EC 4.2.1.1) isoforms II and VII are implicated in neuronal excitation, seizures and neuropathic pain (NP). Their selective inhibition over off-target CAs is expected to produce an anti-NP action devoid of side effects due to promiscuous CA modulation. Here a drug-design strategy based on the observation of (dis)similar...

Herein we report on a new series of hydrazidoureidobenzensulfonamides investigated as inhibitors of the cytosolic human (h) hCA I and II isoforms, as well as the transmembrane, tumor-associated enzymes hCA IX and XII. The reported derivatives contain a 4-substituted piperidine fragment in which the hydrazidoureido linker has been involved as spacer...

Purpose Simple methodology for preparation of metal nanoparticles such as AgNPs uses an methanolic aqueous medium at room temperature or a solvent-free procedure under microwave irradiation. The prepared AgNPs showed a significant antimicrobial effect against Gram-positive bacteria, Gram-negative bacteria, and fungi. Methods The modified methoxypo...

Oxygen evolution reaction (OER) plays a key role on the water splitting process and a high energy conversion efficiency is essential for the definitive advance of hydrogen-based technologies. Unfortunately, green and sustainable development of electrocatalysts for water oxidation is nowadays a real challenge. Herein, a successful mechanochemical me...

A new series of pyrimidine derivatives as human carbonic anhydrases (CA, EC 4.2.1.1) inhibitors is here designed by including a 5-fluorouracil (5-FU) moiety, broadly used anticancer medication, in nitrogenous base modulators of the tumor-associated CAs. Most sulfonamide derivatives efficiently inhibit the target CA IX (KIs in the range 0.47-44.7 nM...

Sulphonamides are biologically important compounds with low toxicity, many bioactivities and cost-effectiveness. Eight sulphonamide derivatives were synthesised and characterised by FT-IR, ¹³C NMR, ¹H NMR, LC-MS and elemental analysis. Their inhibitory effect on AChE, and carbonic anhydrase I and II enzyme activities was investigated. Their antioxi...

The inhibition of δ- and η-class carbonic anhydrases (CAs; EC 4.2.1.1) was poorly investigated so far. Only one δ-CA, TweCA from the diatom Thalassiosira weissflogii, and one η-CA, PfCA, from Plasmodium falciparum, have been cloned and characterised to date. To enrich δ- and η-CAs inhibition profiles, a panel of 22 phenols was investigated for TweC...

The sweeteners saccharin (SAC) and acesulfame K (ACE) recently entered the topic of anticancer human carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, as they showed to selectively inhibit the tumor-associated CAs IX/XII over ubiquitous CAs. A drug design strategy is here reported, which took SAC and ACE as leads and produced a series of 2H-benzo[e][...

Benzothiazole (BTA) belongs to the heterocyclic class of bicyclic compounds. BTA derivatives possesses broad spectrum biological activities such as anticancer, antioxidant, anti-inflammatory, anti-tumour, antiviral, antibacterial, anti-proliferative, anti-diabetic, anti-convulsant, analgesic, anti-tubercular, antimalarial, anti-leishmanial, anti-hi...

We report here a thorough structure-activity relationship (SAR) with piperazinylureido sulfamates as inhibitors of human (h) carbonic anhydrase (CA, EC 4.2.1.1). A SAR investigation over the structure of reported anti-cancer zinc-binder CAIs such as SLC-0111 and S4 was carried out by including the urea outer nitrogen atom into a substituted piperaz...

A primary strategy to combat antimicrobial resistance is the identification of novel therapeutic targets and anti-infectives with alternative mechanisms of action. The inhibition of the metalloenzymes carbonic anhydrases (CAs, EC 4.2.1.1) from pathogens (bacteria, fungi, and protozoa) was shown to produce an impairment of the microorganism growth a...

γ-Class carbonic anhydrases (CAs; EC 4.2.1.1) lack of extended inhibition characterization in comparison to α- and β-class isozymes. For this reason, a panel of 22 phenols was investigated here for the inhibition of the γ-CAs from the pathogenic bacteria Burkholderia pseudomallei (BpsCAγ), Porphyromonas gingivalis (PgiCA), Vibrio cholerae (VchCAγ)...

Chagas disease and leishmaniasis are neglected tropical disorders caused by the protozoans Trypanosoma cruzi and Leishmania spp. Carbonic anhydrases (CAs, EC 4.2.1.1) from these protozoans (α-TcCA and β-LdcCA) have been validated as promising targets for chemotherapic interventions. Many anti-protozoan agents, such as nitroimidazoles, nifurtimox, a...

There is an urgent need for new chemotherapic agents to treat human fungal infections due to emerging and spreading globally resistance mechanisms. Among the new targets that have been recently investigated for the development of antifungal drugs there are the metallo-enzymes Carbonic Anhydrases (CAs, EC 4.2.1.1). The inhibition of the β-CAs identi...

A series of 1,2,3-triazole-bearing benzenesulfonamides was assessed for the inhibition of carbonic anhydrases (CA, EC 4.2.1.1) from bacteria Vibrio cholerae (VchCAα and VchCAβ) and Mycobacterium tuberculosis (β-mtCA3). Growing resistance phenomena against existing antimicrobial drugs are globally spreading and highlight a urgent need of agents endo...

The γ-carbonic anhydrases (CAs, EC 4.2.1.1) present in the Antarctic marine bacteria Pseudoalteromonas haloplanktis and Colwellia psychrerythraea, herein referred to as PhaCA and CpsCA, respectively, were investigated for their activation with a panel of 24 amino acids and amines. Both bacteria are considered Antarctic models for the investigation...

The activation of the δ-class carbonic anhydrase (CAs, EC 4.2.1.1) from the diatom Thalassiosira weissflogii (TweCAδ) was investigated using a panel of natural and non-natural amino acids and amines. The most effective activator of TweCAδ was d-Tyr (KA of 51 nM), whereas several other amino acids and amines, such as L-His, L-Trp, d-Trp, dopamine an...

A series of N'-phenyl-N-hydroxyureas has been prepared by reacting hydroxylamine with aromatic isocyanates. These compounds were investigated as inhibitors of human carbonic anhydrases (hCAs, EC 4.2.1.1), considering four physiologically relevant isoforms, the cytosolic isoforms hCA I and II, and tumor associated, transmembrane isoforms hCA IX and...

The activation of a β-class carbonic anhydrase (CAs, EC 4.2.1.1) from Mycobacterium tuberculosis, encoded by the gene Rv3273 (mtCA 3), was investigated using a panel of natural and non-natural amino acids and amines. mtCA 3 was effectively activated by D-DOPA, L-Trp, dopamine and serotonin, with KAs ranging between 8.98 and 12.1 µM. L-His and D-Tyr...

The present work reported the synthesis of four polymers based on 4,6-dichloro-N-(4-methoxyphenyl)-1,3,5-triazin-2-amine (PMA) as a monomer with different diamines (ethylenediamine (EDPMA), 1,4-diaminobutane (BDPMA), piperazine (PZPMA) and p-phenylenediamine (PDPMA)). The prepared porous organic polymers (POPs) were characterized using Fourier tran...

The α- and β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae, VchCAα, and VchCAβ, were investigated for their activation with natural and non-natural amino acids and amines. The most effective VchCAα activators were L-tyrosine, histamine, serotonin, and 4-aminoethyl-morpholine, which had KAs in the range of...

The β-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Burkholderia pseudomallei, BpsCAβ, that is responsible for the tropical disease melioidosis was investigated for its activation with natural and non-natural amino acids and amines. Previously, the γ-CA from this bacterium has been investigated with the same library of 19...

Six s-triazine-based polymers were prepared through the nucleophilic reaction of 2,4-dichloro-6-substituted s-triazine derivatives with 1,4-diaminobutane employing conventional heating and microwave irradiation. The prepared polymers were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differ...

The carbonic anhydrase superfamily (CA, EC 4.2.1.1) of metalloenzymes is present in all three domains of life (Eubacteria, Archaea, and Eukarya), being an interesting example of convergent/divergent evolution, with its seven families (α-, β-, γ-, δ-, ζ-, η-, and θ-CAs) described so far. CAs catalyse the simple, but physiologically crucial reaction...

A series of monothiocarbamates (MTCs) was investigated for the inhibition of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa, MgCA. These MTCs incorporate various scaffolds, among which aliphatic amine with 1–4 carbons atom in their molecule, morpholine, piperazine, as well as phenethylamine and benzylam...

We cloned, expressed, purified, and determined the kinetic constants of the recombinant α-carbonic anhydrase (rec-MgaCA) identified in the mantle tissue of the bivalve Mediterranean mussel, Mytilus galloprovincialis. In metazoans, the α-CA family is largely represented and plays a pivotal role in the deposition of calcium carbonate biominerals. Our...

A β-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Francisella tularensis (FtuβCA) was cloned and purified, and the anion inhibition profile was investigated. Based on the measured kinetic parameters for the enzyme catalyzed CO2 hydration reaction (kcat of 9.8 x 10⁵ s⁻¹ and a kcat/KM of 8.9 x 10⁷ M⁻¹ s⁻¹), FtuβCA is a highl...

A series of new derivatives was prepared by derivatisation of the 7-amino moiety present in 7-amino-3,4-dihydroquinolin-2(1H)-one, a compound investigated earlier as CAI. The derivatisation was achieved by: i) reaction with arylsulfonyl isocyanates/aryl isocyanates; (ii) reaction with fluorescein isothiocyanate; (iii) condensation with substituted...

A new β-class carbonic anhydrase (CA, EC 4.2.1.1) has been cloned, purified and characterized in the genome of the pathogenic bacterium Francisella tularensis responsible of the febrile illness tularemia. This enzyme, FtuβCA, showed a kcat of 9.8 x 10⁵ s⁻¹ and a kcat/KM of 8.9 x 10⁷ M⁻¹ s⁻¹ for the CO2 hydration, physiological reaction, being one o...

Acridine orange (AO) a fluorescent cationic dye used for the management of human musculoskeletal sarcomas, due to its strong tumoricidal action and accumulation in the acidic environment typical of hypoxic tumors, was used for the preparation of a primary sulfonamide derivative. The rationale behind the drug design is the fact that hypoxic, acidic...

A new γ-carbonic anhydrase (CA, EC 4.1.1.1) was cloned and characterized kinetically in the genome of the bacterial pathogen Burkholderia pseudomallei, the etiological agent of melioidosis, an endemic disease of tropical and sub-tropical regions of the world. The catalytic activity of this new enzyme, BpsCAγ, is significant with a kcat of 5.3×10(5)...

A series of dithiocarbamates (DTCs) was investigated for the inhibition of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa, MgCA, a validated anti-dandruff drug target. These DTCs incorporate various scaffold, among which those of N,N-dimethylaminoethylenediamine, the aminoalcohols with 3-5 carbon atoms...