Papers by mohamed mohyeldin
International Journal of Pharmaceutics, Mar 1, 2023
Applied Biochemistry and Biotechnology. Part A. Enzyme Engineering and Biotechnology, 2011
International Journal of Biological Macromolecules, Jun 1, 2023
The Scientific World Journal, 2014
Galactosidase (-gal) was immobilized by covalent binding on novel-carrageenan gel beads activated... more Galactosidase (-gal) was immobilized by covalent binding on novel-carrageenan gel beads activated by two-step method; the gel beads were soaked in polyethyleneimine followed by glutaraldehyde. 2 2 full-factorial central composite experiment designs were employed to optimize the conditions for the maximum enzyme loading efficiency. 11.443 U of enzyme/g gel beads was achieved by soaking 40 units of enzyme with the gel beads for eight hours. Immobilization process increased the pH from 4.5 to 5.5 and operational temperature from 50 to 55 ∘ C compared to the free enzyme. The apparent after immobilization was 61.6 mM compared to 22.9 mM for free enzyme. Maximum velocity max was 131.2 mol⋅min −1 while it was 177.1 mol⋅min −1 for free enzyme. The full conversion experiment showed that the immobilized enzyme form is active as that of the free enzyme as both of them reached their maximum 100% relative hydrolysis at 4 h. The reusability test proved the durability of the-carrageenan beads loaded with-galactosidase for 20 cycles with retention of 60% of the immobilized enzyme activity to be more convenient for industrial uses.
Biomass Conversion and Biorefinery, Feb 1, 2022
Green-based materials represent a new promising class of ecofriendly and economic adsorbents. Her... more Green-based materials represent a new promising class of ecofriendly and economic adsorbents. Herein, nano zero-valent iron supported-lemon derived biochar (NZVI-LBC) was prepared for the first time and examined in the adsorptive removal of methylene blue as a model pollutant. Different characterization tools were used to ensure the successful fabrication of the NZVI-LBC composite including FTIR, XRD, TEM, XPS, VSM, BET, and zeta potential analysis. It was found that the fabricated NZVI-supported biochar composite attained the propitious adsorbent criteria since it provided a supreme efficient adsorption process at short time. The reckoned maximum adsorption capacity of MB onto NZVI-LBC reached 1959.94 mg/g within merely 5 min. The obtained data clarified that the adsorption process of MB onto NZVI-LBC fitted pseudo 2 nd order kinetic model and Freundlich isotherm model. Besides, the adsorption process of MB onto NZVI-LBC was found to be endothermic in nature. In addition, NZVI-LBC composite revealed an excellent adsorption behavior even after seven cycles. The concrete results reflect the potentiality of NZVI-LBC composite to be a superb candidate to remove cationic pollutants from their aqueous solutions.
Journal of Applied Polymer Science, Feb 25, 2012
The covalent immobilization of penicillin G acylase (PGA) onto the surface of NH 2-poly(vinyl chl... more The covalent immobilization of penicillin G acylase (PGA) onto the surface of NH 2-poly(vinyl chloride) (PVC) membranes was studied. PGA was chosen because it plays a relevant role in the pharmaceutical industry, catalyzing the production of an important intermediate for the industrial production of semisynthetic penicillin and cephalosporine. Because PVC has no functional groups in its structure, in this work, we focused on the functionalization of PVC with primary amine functional groups for the covalent immobilization of PGA. This goal was achieved through an aminoalkylation process of the surface of the PVC membranes with ethylene diamine followed by activation with glutaraldehyde to finally immobilize the enzyme. Different factors affecting the modification and activation processes were studied, and their impacts on the catalytic activity of the immobilized PGA were followed. The functionalized membranes were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy to verify the modification process. In addition, the changes resulting from the modification in physical characteristics, such as surface roughness, water uptake, and mechanical properties, were monitored. V C 2011
International Journal of Biological Macromolecules, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
DESALINATION AND WATER TREATMENT, 2021
In the original version of the article "Development of newspaper/polystyrene composite adsorbent ... more In the original version of the article "Development of newspaper/polystyrene composite adsorbent for oil spills removal" published in vol. 229, July 2021, pp. 167-183 the affiliation of T.M. Tamer and A.M. Omer was incorrect. The corrected version has subsequently been published.
Processes, Jan 22, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Biological Macromolecules, Jun 1, 2022
DESALINATION AND WATER TREATMENT, 2019
Scientific Reports, Aug 16, 2021
An efficient composite was constructed based on aminated chitosan (NH 2 Cs), attapulgite (ATP) cl... more An efficient composite was constructed based on aminated chitosan (NH 2 Cs), attapulgite (ATP) clay and magnetic Fe 3 O 4 for adsorptive removal of Cr(VI) ions. The as-fabricated ATP@Fe 3 O 4-NH 2 Cs composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), Zeta potential (ZP), Vibrating Sample Magnetometer (VSM), Brunauer-Emmett-Teller method (BET) and X-ray photoelectron spectroscope (XPS). A significant improve in the adsorption profile was established at pH 2 in the order of ATP@Fe 3 O 4-NH 2 Cs(1:3) > ATP@Fe 3 O 4-NH 2 Cs(1:1) > ATP@Fe 3 O 4-NH 2 Cs(3:1) > Fe 3 O 4-NH 2 Cs > ATP. The maximum removal (%) of Cr(VI) exceeded 94% within a short equilibrium time of 60 min. The adsorption process obeyed the pseudo 2nd order and followed the Langmuir isotherm model with a maximum monolayer adsorption capacity of 294.12 mg/g. In addition, thermodynamics studies elucidated that the adsorption process was spontaneous, randomness and endothermic process. Interestingly, the developed adsorbent retained respectable adsorption properties with acceptable removal efficiency exceeded 58% after ten sequential cycles of reuse. Besides, the results hypothesize that the adsorption process occurs via electrostatic interactions, reduction of Cr(VI) to Cr(III) and ionexchanging. These findings substantiate that the ATP@Fe 3 O 4-NH 2 Cs composite could be effectively applied as a reusable adsorbent for removing of Cr(VI) ions from aqueous solutions. Indeed, the recent prosperity of industries has obvious positive impacts on economic growth; however, disposal of the industrial effluents into the water bodies without reasonable treatment can undoubtedly eradicate mankind 1,2. One of the most toxic pollutants that pose jeopardy to human health as well as the entire environment is hexavalent chromium (Cr(VI)). Therefore, Cr(VI) has been deemed to be carcinogenic, mutagenic and displayed higher toxicity due to its enormously mobile in the surroundings 3,4. Subsequently, the World Health Organization has authorized that the maximum limit of Cr(VI) in potable water should not exceed 0.05 mgL −15,6. Despite these mentioned risks, there are number of significant industries mainly based on Cr(VI) including steel, textile, dyeing, cement, electroplating and leather tanneries 7,8. Therefore, several researches have been focused on the removal of Cr(VI) ions from their aqueous solutions via diverse techniques including coagulation 9 , chemical precipitation 10 , adsorption 11,12 , membrane separation 13 , catalysis 14 , ion exchange 15 and electrodialysis 16. Principally, there are strict criteria to select the appropriate removal technique such as low energy consumption, process simplicity, renewability and the low operational cost 17. Accordingly, adsorption can be considered as the most preferred technique to remove Cr (VI) from aqueous solution 18,19. Consequently, a plethora of the adsorbents such as activated carbon, clay materials, polymers, natural products, and metal/mixed oxide nanoparticles have been used for the removal of Cr(VI) from wastewater 20,21. Chitosan (Cs) is a cationic polysaccharide polymer that is easily obtained via N-deacetylation of chitin, the essential component of the exoskeleton of crustaceans like shrimp, fungi, crab and insects 22,23. Owing to its unparalleled merits such as biocompatibility, polyelectrolyte properties, recyclability, hydrophilicity, biodegradability and adhesion properties, chitosan has a significant deal of interest as an efficient cationic adsorbent for
Arabian Journal of Chemistry, Jul 1, 2014
Poly(vinyl alcohol), PVA is a polymer of great importance because of its many appealing character... more Poly(vinyl alcohol), PVA is a polymer of great importance because of its many appealing characteristics specifically for various pharmaceutical and biomedical applications. Physically crosslinked hydrogel membranes composed of different amounts of hydroxyethyl starch (HES) in (PVA) and ampicillin were prepared by applying freeze-thawing method. This freezing-thawing cycle was repeated for three consecutive cycles. Physicochemical properties of PVA-HES membrane gel such as gel fraction, swelling, morphology, elongation, tensile strength, and protein adsorption were investigated. Introducing HES into freeze-thawed PVA structure affected crystal size distribution of PVA; and hence physicochemical properties and morphological structure have been affected. Increased HES concentration decreased the gel fraction %, maximum strength and break elongation. Indeed it resulted into a significant incrementing of the swelling ability, amount of protein adsorption, broader pore size, and pore distribution of membrane morphological structure. Furthermore, an increase in HES concentration resulted in better and still lower thermal stability compared to virgin PVA and freeze-thawed PVA. The maximum weight loss of PVA-HES hydrogel membranes ranged between 18% and 60% according to HES content, after two days of degradation in phosphate buffer saline (PBS), which indicates they are biodegradable. Thus, PVA-HES hydrogel membranes containing ampicillin could be a novel approach for biomedical application e.g. wound dressing purposes.
Research Square (Research Square), Jun 13, 2022
Carrageenan is one of the most common carbohydrates utilised in the entrapment industry to immobi... more Carrageenan is one of the most common carbohydrates utilised in the entrapment industry to immobilise cells and enzymes. However, it lacks functionality. Carrageenan has been grafted to produce fructose by covalently immobilising glucose isomerase (GI). Fructose is one of the most widely used sweeteners in beverages, food production, and the pharmaceutical business. Up to 91.1 U g-1 gel beads are immobilised by the grafted beads. Immobilized GI has a V max of 13.8 times that of the free enzyme. The immovability and tolerance of the gel beads immobilised with GI over 15 consecutive cycles were demonstrated in a reusability test, with 88 percent of the enzyme's original activity retained, compared to 60 percent by other authors. These ndings are encouraging for high-fructose corn syrup producers.
International Journal of Pharmacy, 2016
PVC polymer has been taken the attention of the scientists in early decay as blood containers ins... more PVC polymer has been taken the attention of the scientists in early decay as blood containers instead of glass containers. To increase the stability and flexibility of the PVC, several compounds such as Di-ethylhexyl phthalate (DEHP) and ethylene oxide were applied. Some recent reports recorded the risks of these compounds toward public health. In the present study, Antimicrobial PVC films containing different amounts of eugenol as a plasticizer were prepared using traditional casting method. The physical and mechanical properties of PVC membranes e.g. surface wettability were investigated. The increase of eugenol content demonstrated an increase in surface hydrophilicity and elongation to break the film. Thermal analysis exhibited a decrease of polymer thermal stability by increasing eugenol concentration. However, the antibacterial activities against six different bacterial strains; three Gram positive: Staphylococcus aureus, Streptococcus pyogenes and Bacillus cereus as well as, three Gram negative: Pseudomonas aeruginosa, Salmonella sp. and Escherichia coli were promoted by addition of eugenol. Although the natural source of eugenol, the bio-evaluation of plasticized membranes showed an increase in hemolysis percent (%) and thrombus weight. It can be concluded that the addition of eugenol to PVC needs to further studies for applying in blood bags.
Journal of Applied Polymer Science, Nov 29, 2011
The covalent immobilization of penicillin G acylase (PGA) onto the surface of NH 2-poly(vinyl chl... more The covalent immobilization of penicillin G acylase (PGA) onto the surface of NH 2-poly(vinyl chloride) (PVC) membranes was studied. PGA was chosen because it plays a relevant role in the pharmaceutical industry, catalyzing the production of an important intermediate for the industrial production of semisynthetic penicillin and cephalosporine. Because PVC has no functional groups in its structure, in this work, we focused on the functionalization of PVC with primary amine functional groups for the covalent immobilization of PGA. This goal was achieved through an aminoalkylation process of the surface of the PVC membranes with ethylene diamine followed by activation with glutaraldehyde to finally immobilize the enzyme. Different factors affecting the modification and activation processes were studied, and their impacts on the catalytic activity of the immobilized PGA were followed. The functionalized membranes were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy to verify the modification process. In addition, the changes resulting from the modification in physical characteristics, such as surface roughness, water uptake, and mechanical properties, were monitored. V C 2011
Desalination and Water Treatment, Feb 1, 2012
This study deals with the development of a clean and safe process for water pollution remediation... more This study deals with the development of a clean and safe process for water pollution remediation. We studied the potential use of Imino Diacetic Acid (IDA) activated calcium alginate beads for removal of cationic dyes from colored effluents in dynamic batch mode. Methylene blue (MB) has been chosen as a dye model for the study. The parameters that affect the
journal of applied pharmaceutical science, 2015
In this study, the thermo-sensitive copolymers were synthesized by graft copolymerization of poly... more In this study, the thermo-sensitive copolymers were synthesized by graft copolymerization of poly N isopropyl acrylamide (PNIPAm) onto chitosan (Ch) and aminated chitosan (AmCh) derivative. Free radical polymerization using potassium persulphate (KPS) as initiator was used for performing the grafting process. FTIR, TGA and DSC analysis were used to verify the structure of the resulting graft copolymers. The thermal sensitivity of the prepared copolymers was determined by monitoring the phase transition temperature at 550nm using a UV-VIS spectrophotometer. The results show that the transition of the PNIPAm-g-Ch is sharper than that of the PNIPAmg-AmCh and the transition , in both cases, became sharper as increase the PNIPAm grating percentage.
Scientific Reports, Feb 9, 2021
Hemorrhage is the major hindrance over the wound healing, which triggers microbial infections and... more Hemorrhage is the major hindrance over the wound healing, which triggers microbial infections and might provoke traumatic death. Herein, new hemostatic and antibacterial PVA/Kaolin composite sponges were crosslinked using a freeze-thawing approach and boosted by penicillinstreptomycin (Pen-Strep). Physicochemical characteristics of developed membranes were analyzed adopting Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), a thermal gravimetric analyzer (TGA), and differential scanning calorimetry (DSC). Furthermore, the impacts of kaolin concentrations on porosity, swelling behavior, gel fraction, and degradation of the membranes were investigated. SEM analyses revealed a spongy-like structure of hydrogels associated with high dispersion of kaolin inside PVA matrix. The thermal characteristics of PVA/Kaolin were significantly ameliorated compared to the prime PVA. Moreover, the results exhibited significant variations of swelling performance, surface roughness and pore capacity due to the alterations of kaolin contents. Besides, the adhesive strength ability was manifestly enhanced for PVA-K0.1 sponge. Biomedical evaluations including antibacterial activity, blood clotting index and thrombogenicity of the membranes were studied. The contact of PVA/Kaolin to blood revealed notable augmentation in blood clotting. Furthermore, the incorporation of kaolin into PVA presented mild diminution in antibacterial activities. Moreover, PVA/Kaolin composites illustrated no cellular toxicity towards fibroblast cells. These remarkable features substantiate that the PVA-K0.1 sponge could be applied as a multifunctional wound dressing. The leading challenge of injuries treatment is the excessive hemorrhage, which might result in approximately 40% of death, particularly in injuries caused either on the combat zone or accidents 1. Extreme bleeding could trigger serious and uncontrollable complications; for instance, hypovolemic shock, microbial infections, traumatic death 2. Hence, prompt management of such bleeding necessitates effective treatments utilizing biocompatible and hemostatic materials. Previous studies put forward that systemic hemostatic and injectable compounds including fibrin, thrombin and growth factors have been implemented to tackle the blood flow in severe patients 3 ; however, dangerous consequences have been explored, such as internal clotting and pulmonary embolism 4. For these reasons, topical clotting materials possess intrinsic hemostatic properties, including as collagen 5 , zeolite 6 and chitosan 7 have been drawing great interest. Blood coagulation mechanism accomplishes in three progressive stages: (1) initiation that includes thrombin development, (2) amplification, in which aggregation and activation of platelets could be perceived, (3) proliferation, which is identified by fibrin construction and steadiness of the platelet clot. The effect of used hemostatic
Carbohydrate Polymers, Nov 1, 2021
The tremendous development in the industrial sector leads to discharging of the several types of ... more The tremendous development in the industrial sector leads to discharging of the several types of effluents containing detrimental contaminants into water sources. Lately, the proliferation of toxic anions particularly phosphates and nitrates onto aquatic systems certainly depreciates the ecological system and causes a deadly serious problem. Chitosan (Cs) is one of the most auspicious biopolymer adsorbents that are being daily developed for removing of various contaminants from polluted water. This is due to its unparalleled benefits involving biocompatibility, non-toxicity, facile modifications and low-cost production. Nevertheless, chitosan displays considerable drawbacks including low adsorption capacity, low surface area and lack of reusability. Therefore, few findings have been established regarding the aptitude of modified chitosan-based adsorbents towards phosphate and nitrate anions. This review elaborates an overview for the current advances of modified chitosan based-adsorbent for phosphate and nitrate removal, in specific multivalent metals-modified chitosan, clays and zeolite-modified chitosan, magnetic chitosan and carbon materials-modified chitosan. The efforts that have been executed for enriching their adsorption characteristics as well as their possible adsorption mechanisms and reusability were well addressed. Besides, the research conclusions for the optimum adsorption conditions were also discussed, along with emphasizing the foremost research gaps and future potential trends that could motivate further research and innovation to find best solutions for water treatment problems facing the world.
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Papers by mohamed mohyeldin