Browsing by Author "Mohsen, Reham"

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Characterization of thermo and pH responsive NIPAM based microgels and their membrane blocking potential
(Elsevier, 2013) Mohsen, Reham; J. Vine, George; Majcen, Natasa; D. Alexander, Bruce; J Snowden, Martin
This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pHresponsive p(NIPAM)/acrylic acid (AA) microgels. Three microgels were synthesized using surfactant free emulsion polymerization technique, these are p(NIPAM), p(NIPAM)-co-AA 95:5% (w/w) and p(NIPAM)- co-AA 90:10% (w/w). Dynamic light scattering was used to study the behavior of diluted microgel dispersions (0.5%, w/w p(NIPAM)), while rheology was used to study the viscosity of 2% (w/w) p(NIPAM) dispersions. The characterization data indicate the swelling/deswelling and flocculation/deflocculation behavior of the microgels. The conditions required for flocculation were used to test the ability of the microgel dispersions to block a membrane of pore size 5 m. In 3 h, p(NIPAM), p(NIPAM) 5% AA (w/w) and p(NIPAM)10% AA (w/w) blocked the membrane (decrease the flow rate) by 96.16, 59.44 and 59.8% respectively. Thus,the controlled flocculation of microgels may be used in applications where pore blocking is important such as the treatment of dentinal hypersensitivity, given that the VPTT of p(NIPAM) is ≈34 ◦C, which is very close to the human body temperature.
Cleaner and Sustainable Synthesis of High Quality Monoglycerides by use of Enzyme Technologies: Techno-economic and Environmental study for Monolaurin
(2022-09) Mustafa, Ahmad; Fathy, Sara; Kutlu, Ozben; Niikura, Fumiya; Inayat, Abrar; Mustafa, Muhammad; Abdellatie, Tamer M.M.; Bokhari, Awais; Samuel, David; Pastore, Carlo; Bitonto, Luigi; Mohsen, Reham
Currently, monoglycerides (MG) are produced using a complicated energy intensive technology that contributes negatively toward greenhouse gas mitigation. This work suggests a cleaner and simpler one-step enzymatic production of α-monolaurin in an inert membrane reactor, where the reaction and enzyme separation are conducted simultaneously in one unit. Candida antarctica lipase (Lipozyme 435) was used to catalyze the esterification reaction between lauric acid and glycerin in a solvent-free system under mild temperatures. Response surface methodology was used to optimize the reaction conditions. The optimal conditions were a molecular sieve of 14.85% w/w, a temperature of 56.95°C, an enzyme amount of 5.38% w/w, and a molar ratio of 4.75% w/w. The gas chromatography (GC) analysis showed that the α-monolaurin percentage was 49.5% when the enzymatic process (ENZ) was used. The conventional chemical (CHEM) and autocatalytic (AUT) esterification methods were also performed to study their proportional MG yields. The GC results showed the MG percentages of 43.9% and 41.7% for CHEM and AUT, respectively. Economic analysis was also conducted for the suggested enzymatic technique, and the findings were compared with those of the CHEM and AUT technologies. Using a plant capacity of 4950 t/year and 11% interest for the proposed ENZ process, the total capital investment of α-monolaurin production was preferably four times less than that of the CHEM process and three times less than that of the AUT method, presenting investment possibilities. However, the ENZ process showed the least profitability (net profit per day) among the three processes. Nevertheless, the return on investment and net present value for the ENZ process were preferably higher than those of CHEM and AUT because of its interestingly lower inside battery limit plant cost and less energy consumption. The AUT/CHEM processes generated a total carbon dioxide (CO2 ) exhaust of t CO2 678.7 eq./year. In contrast, the ENZ process exhausted a total CO2 of only 50 t CO2 eq./year. The present integrated techno-economic and environmental study of α-monolaurin production emphasizes the green and cost benefits of the proposed ENZ technology.
Deposition of fluorescent NIPAM-based nanoparticles on solid surfaces: quantitative analysis and the factors affecting it
(Elsevier, 2014) Mohsen, Reham; B Thorne, Joanna; D. Alexander, Bruce; J. Snowden, Martin
Recently, responsive surfaces have attracted attention due to their potential applications. Reported research have studied the deposition of environmentally responsive particles on different surfaces, qualitatively tested their response to environmental conditions and studied their possible applications. In this work, novel fluorescent temperature-sensitive nanoparticles were synthesized using a surfactant free emulsion polymerization technique: poly(N-isopropylacrylamide-co-5% vinyl cinnamate) (p(NIPAM)5%VC). The new particles were characterized using dynamic light scattering and fluorescence spectroscopy. A novel sensitive method for the quantitative analysis of p(NIPAM) 5% VC using fluorescence spectroscopy was developed to determine the concentration of nanoparticle dispersions. This was further used to quantitatively determine the mass of nanoparticles deposited per unit area of glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and teflon at 25 °C and 60 °C. Factors affecting the adsorption/desorption of the nanoparticles were studied, including the effect of substrate surface charge, surface roughness (using atomic force microscopy, AFM), hydrophilicity/hydrophobicity and the temperature at which the adsorption/desorption experiments were carried out. The results show that the effect of surface charge is the most significant, followed by that of surface roughness and temperature. Meanwhile, the influence of the hydrophobicity/hydrophilicity of the surface on the adsorption/desorption of nanoparticles appears to be far less significant than the previously mentioned factors.
The development of a novel smart material based on colloidal microgels and cotton
(Elsevier Ltd, 5/23/2018) Majcen, Natasa; Mohsen, Reham; Snowden, Martin J; Mitchell, John C; Voncina, Bojana
Colloidal microgels are often described as “smart” due to their ability to undergo quite dramatic conformational changes in response to a change in their environmental conditions (e.g. temperature, pH). A range of novel smart materials were developed by the incorporation of colloidal microgels into cotton fabric. A series of microgels have been prepared by a surfactant free emulsion polymerisation based on N-isopropylacrylamide (NIPAM) monomer. Poly(NIPAM) is a thermosensitive polymer which undergoes a conformational transition close to the human skin temperature. Poly(NIPAM) was co- polymerized acrylic acid (AA), to prepare pH / temperature-sensitive microgels. Microgel particles were characterized by scanning electron microscopy (SEM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, and dynamic light scattering (DLS). This research aims at coupling microgel particles onto cotton fibers and comparing between different attachment techniques. The coupling reactions between microgels and cotton cellulose are only feasible if they both have appropriate functionalities. For microgels, this was achieved by using different initiators which introduce different functional groups on the particle surface and different surface charges. Cotton samples were successfully modified by carboxymethylation, periodate oxidation, grafting of 1,2,3,4-butanetetracarboxylic acid, and chloroacetylation in order to target possible reactions with the terminal functional groups of the microgel particles. Microgels were attached to the cotton fabrics using different methods and the bonds formed were determined by ATR-FTIR spectroscopy and SEM. The reaction yields were quantified gravimetrically and the maximum weight increase of cotton samples due to the attached microgels was around 24% (w/w).
Effect of two different Materials; Microgel p(NIPAM) and Sodium Fluoride on the Depth and Degree of Occlusion of the Dentinal Tubules at Different Dentin Depths
(Biocore Group, 05/05/2021) Hamada, Salma Basyouni; Hamza, Nermeen; Mohsen, Reham; Kamel, Faten
Objectives: To evaluate the effect of two different desensitizing materials microgel p(NIPAM) and 5% sodium fluoride (NaF) on the degree of occlusion and depth of penetration of the dentinal tubules on superficial and deep dentin after immediate application and thermocycling using environmental scanning electron microscope. Materials and Methods: 20 non- carious, non-restored molars were included. Each tooth was cut in order to obtain four quadrants. Specimens were divided into two groups according to aging. Then they were further sub-divided into two subgroups according to dentin depths. Further subdivision into four divisions according to the desensitizing material. The specimens were evaluated for the depth of penetration and degree of occlusion of each material using environmental scanning electron microscope. One-way ANOVA followed by Tukey post hoc test was used to compare between more than two groups in non-related samples. Independent sample t-test was used to compare between two groups in non- related samples. Results: p(Nipam) showed the highest mean value without statistically significant difference with the varnish group regarding the degree of occlusion, either on immediate evaluation or after thermocycling. Conclusion: Better occlusion of dentinal tubules was shown on immediate testing rather than after thermocycling regardless the dentin type, however, more depth of penetration was shown after thermocycling regardless the dentin type. All the desensitizing materials showed better occlusion and depth of penetration in superficial dentin than in deep dentin. Clinical relevance: p(NIPAM) microgel is a promising material in the treatment of dentin hypersensitivity, however further in-vivo studies are needed.
Enhancement of Vitamin C’s Protective Effect against ThimerosalInduced Neurotoxicity in the Cerebral Cortex of Wistar Albino Rats: An In Vivo and Computational Study
(American Chemical Society, 2024-01) Hassan, Amr; Mohsen, Reham; Rezk, Ahmed; Bangay, Gabrielle; Rijo, Patrícia; Soliman, Mona F. M; Hablas, Mohamed G. A; Swidan, Khalifa AbdulRazik K; Mohammed, Tahseen S; Zoair, Mohammad A; Mohamed, Abir A. Khalil; Abdalrhman, Tamer I; Desoky, Ahmad M. Abdel-aleem; Mohamed, Dalia D; Mohamed, Doaa D; Abd El Maksoud, Ahmed I; Mohamed, Aly F
Vitamin C was examined to ameliorate the neurotoxicity of thimerosal (THIM) in an animal model (Wistar albino rats). In our work, oxidative and antioxidative biomarkers such as SOD, LPO, and GSH were investigated at various doses of THIM with or without concurrent vitamin C administration. Furthermore, the adverse effects of THIM on hepatic tissue and cerebral cortex morphology were examined in the absence or presence of associated vitamin C administration. Also, we studied the effect of vitamin C on the metallothionein isoforms (MT-1, MT-2, and MT-3) in silico and in vivo using the RT-PCR assay. The results showed that the antioxidant biomarker was reduced as the THIM dose was raised and vice versa. THIM-associated vitamin C reduced the adverse effects of the THIM dose. The computation studies demonstrated that vitamin C has a lower ΔG of −4.9 kcal/mol compared to −4.1 kcal/mol for THIM to bind to the MT-2 protein, which demonstrated that vitamin C has a greater ability to bind with MT-2 than THIM. This is due to multiple hydrogen bonds that exist between vitamin C and MT-2 residues Lys31, Gln23, Cys24, and Cys29, and the sodium ion represents key stabilizing interactions. Hydrogen bonds involve electrostatic interactions between hydrogen atom donors (e.g., hydroxyl groups) and acceptors (e.g., carbonyl oxygens). The distances between heavy atoms are typically 2.5−3.5 Å. H-bonds provide directed, highaffinity interactions to anchor the ligand to the binding site. The five H-bonds formed by vitamin C allow it to form a stable complex with MT, while THIM can form two H-bonds with Gln23 and Cys24. This provides less stabilization in the binding pocket, contributing to the lower affinity compared to vitamin C. The histopathological morphologies in hepatic tissue displayed an expansion in the portal tract and the hepatocytes surrounding the portal tract, including apoptosis, binucleation, and karyomegaly. The histopathological morphologies in the brain tissue revealed a significant decrease in the number of Purkinje cells due to THIM toxicity. Interestingly, THIM toxicity was associated with hemorrhage and astrogliosis. Both intracellular and vasogenic edema appeared as the concentrations of THIM rose. Finally, vitamin C ameliorated the adverse effect on the cerebral cortex in Wistar albino rats.
Functionalized Poly(N-isopropylacrylamide)-Based Microgels in Tumor Targeting and Drug Delivery
(MDPI, 08/11/2021) Campora, Simona; Mohsen, Reham; Passaro, Daniel; Samir, Howida; Ashraf, Hesham; Al-Mofty, Saif El-Din; Diab, Ayman A; El-Sherbiny, Ibrahim M; Snowden, Martin J; Ghersi, Giulio
Abstract: Over the past several decades, the development of engineered small particles as targeted and drug delivery systems (TDDS) has received great attention thanks to the possibility to over- come the limitations of classical cancer chemotherapy, including targeting incapability, nonspecific action and, consequently, systemic toxicity. Thus, this research aims at using a novel design of Poly(N-isopropylacrylamide) p(NIPAM)-based microgels to specifically target cancer cells and avoid the healthy ones, which is expected to decrease or eliminate the side effects of chemotherapeutic drugs. Smart NIPAM-based microgels were functionalized with acrylic acid and coupled to folic acid (FA), targeting the folate receptors overexpressed by cancer cells and to the chemotherapeutic drug doxorubicin (Dox). The successful conjugation of FA and Dox was demonstrated by dynamic light scattering (DLS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), UV-VIS analysis, and differential scanning calorimetry (DSC). Furthermore, viability assay performed on cancer and healthy breast cells, suggested the microgels’ biocompatibility and the cytotoxic effect of the conjugated drug. On the other hand, the specific tumor targeting of synthetized microgels was demonstrated by a co-cultured (healthy and cancer cells) assay monitored using confocal microscopy and flow cytometry. Results suggest successful targeting of cancer cells and drug release. These data support the use of pNIPAM-based microgels as good candidates as TDDS.
Selective synthesis of alpha monoglycerides by a clean method: Techno-economic and environmental assessment
(Elsevier, 2022-04-12) Mustafa, Ahmad; Niikura, Fumiya; Pastore, Carlo; Allam, Hoda A; Hassan, Omnia Bassam; Mustafa, Muhamad; Inayat, Abrar; Salah, Sameh A; Abdel Salam, Ahmed; Mohsen, Reham
This work proposes an alternative green and selective biocatalytic route for Glycerin Mono- stearate (α-monostearin) production. The conventional method of production uses an elevated temperature. Apart from the high energy consumption, such high temperatures darken the final product’s color, lead to random reactions, and produce high orders of diglycerides and tri- glycerides instead of monoglycerides. The proposed production process was performed by esterifying stearic acid with glycerin in an organic medium using Candida antarctica lipase (Novozym 435) at a mild temperature. The reaction conditions were optimized using the response surface methodology (RSM): optimum conditions were a temperature of 60 ◦C, glycerin to stearic acid molar ratio of 8:1, and Novozym 435 amount of 6% w/w. The solvent addition remarkably improved the α-monostearin yield to nearly 80% without the need for the energy-intensive distillation step. The conventional autocatalytic esterification (AUT) process was also per- formed to investigate the comparative monoglyceride yield, and it was found to be 22.5%. Proton nuclear magnetic resonance and gas-chromatography confirmed that α-monostearin could be produced with the highest purity using the proposed enzymatic method (ENZ). Economic and environmental analyses were also conducted for the proposed ENZ process, and the results were compared with those of the AUT process. The total capital investment of α-monostearin pro- duction, considering a projected capacity of 4950 t year− 1 and 11% interest for the proposed ENZ process, was favorably 2.5 times lower than that of the AUT process, suggesting a promising investment opportunity. However, the total production costs showed unfavorable negative net present value (NPV) and return on investment (ROI) for the ENZ process and favorable positive NPV and ROI for the AUT process, indicating that the proposed venture is not profitable for α-monostearin production. However, the process can be profitable at improved operational sta- bility of Novozym 435 up to 1 kg per 3-ton product. The carbon footprint was calculated on the basis of the given capacity and conditions of 50 and 656 t CO2 eq./year for the ENZ and AUT processes, respectively. The synthesis of α-monostearin using the proposed route can be consid- ered a building block toward a cleaner large-scale production of α-monoglycerides.