ORCID Profile
0000-0002-6674-4542
Current Organisations
University of Queensland
,
King Fahd University of Petroleum and Minerals
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Publisher: Elsevier BV
Date: 07-2019
Publisher: American Chemical Society (ACS)
Date: 21-04-2007
DOI: 10.1021/LA700378Q
Abstract: We present the first study of the directed disassembly of a protein network at the air-water interface by the synergistic action of a surfactant and an enzyme. We seek to understand the fundamentals of protein network disassembly by using rubisco adsorbed at the air-water interface as a model. We propose that rubisco adsorption at the air-water interface results in the formation of a fishnet-like network of interconnected protein molecules, capable of transmitting lateral force. The mechanical properties of the rubisco network during assembly and disassembly at the air-water interface were characterized by direct measurement of laterally transmitted force through the protein network using the Cambridge interfacial tensiometer. We have shown that, when used in idually, either 2 ppm of the surfactant, sodium dodecyl benzyl sulfonate (SDOBS), or 2 ppm of the enzyme, subtilisin A (SA), were insufficient to completely disassemble the rubisco network within 1 h of treatment. However, a combination of 2 ppm SDOBS and 2 ppm SA led to almost complete disassembly within 1 h. Increasing the concentration of SA in the mixture from 2 to 10 ppm, while keeping the SDOBS concentration constant, significantly decreased the time required to completely disassemble the rubisco network. Furthermore, the initial rate of network disassembly using formulations containing SDOBS was surprisingly insensitive to this increase in SA concentration. This study gives insight into the role of lateral interactions between protein molecules at interfaces in stabilizing interfacial protein networks and shows that surfactant and enzyme working in combination proves more effective at disrupting and mobilizing the interfacial protein network than the action of either agent alone.
Publisher: Springer Science and Business Media LLC
Date: 12-2014
Publisher: Elsevier BV
Date: 09-2015
Publisher: Springer Science and Business Media LLC
Date: 05-02-2019
Publisher: Bentham Science Publishers Ltd.
Date: 02-2018
DOI: 10.2174/1573413713666171201150215
Abstract: Nano-Co3O4 has been used in various technological areas and applications such as electrochemical sensors and electrochemical water splitting. Even though many efforts have been expended to prepare nano-Co3O4, the development of novel methods to prepare Co3O4 using simple processes and at low cost remain a topic of interest. Besides, it could be economic and useful if the synthesized nanoparticle could be applied as efficient electrocatalyst upon its immobilization on a cheap base electrode material by very simple method for various practical applications including renewable energy. We prepared nano-Co3O4 by a direct thermal decomposition of an inexpensive, simple and widely available cobalt inorganic precursor, such as Co(NO3)2·6H2O without any type of prereaction or processing. The nano-Co3O4 was immobilized on filter-paper-derived carbon electrode by drop-drying method for applying as electrode materials toward water electrooxidation. The X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy analysis confirmed the formation of short nanorods of single-phase Co3O4 upon thermal decomposition of Co(NO3)2·6H2O at 520°C. The electrocatalytic properties of the nano- Co3O4 were evaluated after immobilizing it on a cheap carbon electrode derived from normal filter paper. The modified electrode showed good electrocatalytic properties toward water oxidation in an alkaline solution. In conclusion, we developed a very simple, straight-forward and economic method for preparation of nano-Co3O4 and immobilized it on very cheap carbon electrode for evaluating its electrocatalytic properties. Due to the high electrocatalytic properties, the prepared nano-Co3O4 could potentially play an important role in various practical fields.
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.JCIS.2010.07.030
Abstract: The enzymatic cleaning of a rubisco protein stain bound onto Surface Plasmon Resonance (SPR) biosensor chips having a dye-bound upper layer is investigated. This novel method allowed, for the first time, a detailed kinetic study of rubisco cleanability (defined as fraction of adsorbed protein removed from a surface) from dyed surfaces (mimicking fabrics) at different enzyme concentrations. Analysis of kinetic data using an established mathematical model able to decouple enzyme transfer and reaction processes [Onaizi, He, Middelberg, Chem. Eng. Sci. 64 (2008) 3868] revealed a striking effect of dyeing on enzymatic cleaning performance. Specifically, the absolute rate constants for enzyme transfer to and from a dye-bound rubisco stain were significantly higher than reported previously for un-dyed surfaces. These increased transfer rates resulted in higher surface cleanability. Higher enzyme mobility (i.e., higher enzyme adsorption and desorption rates) at the liquid-dye interface was observed, consistent with previous suggestions that enzyme surface mobility is likely correlated with overall enzyme cleaning performance. Our results show that reaction engineering models of enzymatic action at surfaces may provide insight able to guide the design of better stain-resistant surfaces, and may also guide efforts to improve cleaning formulations.
Publisher: Hindawi Limited
Date: 28-08-2022
DOI: 10.1155/2022/9098101
Abstract: Effective in situ scavenging of hydrogen sulfide (H2S) while drilling a sour formation is critical for limiting the prevalent related impacts and safety hazards. Thus, it is necessary to develop a specialized additive that can selectively react with H2S and remove it without generating harmful byproducts or impairing drilling fluid performance. Additionally, waste management and utilization will transfer the waste from being an environmental and economic burden to a valuable commodity. Accordingly, we report herein the management of steelmaking waste through its utilization as a novel H2S scavenger for water-based drilling fluids, as well as the evaluation of the effects of the steelmaking waste dosage (1, 2, and 3 g) on the mud H2S scavenging capability and key properties. The H2S scavenging capacity of the waste-containing mud was investigated and compared to that of the base mud and fluids containing the commercial scavengers (triazine- and iron gluconate-based materials). In addition, the mud rheology, alkalinity, and filtering performance were studied in the presence and absence of the waste, and the findings were compared to those of commercial scavengers. This study showed that adding 1, 2, and 3 g of the steelmaking waste to the base drilling fluid significantly improved the H2S scavenging capacity by 105, 399, and 503%, respectively, while the triazine- and iron gluconate-based materials increased the capacity by 179 and 131%. Similarly, when the proportion of the steelmaking waste increased, the rheological parameters, comprising apparent viscosity, plastic viscosity, and yield point, slightly increased. The inclusion of the steelmaking waste reduced mud pH to 10.4, 9.8, and 8.5 with a content of 1, 2, and 3 g, respectively, compared to 11.0 for the base mud, 11.1 for triazine-based material, and 7.9 for iron gluconate-based scavenger. When 1 and 2 g of the steelmaking waste were added, the obtained filtrated liquid volume was preferably lower than the base mud and even the commercial scavengers-contained muds. As a result, 2 g of steelmaking waste could be added for enhanced mud performance. Nevertheless, higher amounts of the steelmaking waste could be used instead to achieve maximal H2S scavenging capability, with an extra alkalinity controller added to ensure attaining the practical recommended properties.
Publisher: Springer Science and Business Media LLC
Date: 05-03-2019
Publisher: Springer Science and Business Media LLC
Date: 27-03-2017
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 08-2020
Publisher: SPE
Date: 23-04-2018
DOI: 10.2118/192450-MS
Abstract: Asphaltene aggregation is one of the biggest problems in the oil and gas industry for both upstream and downstream processes. It called the cholesterol of crude oil since it can deposit on the reservoirs pores and block it. It can also plug the production tubes and pipelines which could cost millions of dollars. One of the solutions is adding different chemicals such as asphaltene dispersants (ADs) or asphaltene inhibitors (AIs). ADs reduce asphaltene particle size which will keep them in the crude while AIs prevent the asphaltene aggregation by shifting the onset pressure of asphaltene. In this paper, three different asphaltene inhibitors were tested and investigated thoroughly with different concentrations for heavy Arabian crude oil. Several tests were performed: asphaltene inhibitors efficiency was tested using laser scanner analysis and asphaltene stability was investigated by using spot test method and asphaltene solubility class index. The results showed that the Arabian crude oil has a high asphaltene content and it reasonably stable. Two of the inhibitors (SF-1742 and AI-410) have showed better efficiency than the third inhibitor (AI- 108) in the inhibitors efficiency test with low optimum concentration.
Publisher: American Chemical Society (ACS)
Date: 18-11-2020
Publisher: Elsevier BV
Date: 09-2009
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Publisher: Springer Science and Business Media LLC
Date: 03-2018
DOI: 10.1007/S00249-018-1289-Z
Abstract: The dynamic adsorption of the anionic biosurfactant, surfactin, at the air-water interface has been investigated in this work and compared to those of two synthetic surfactants: the anionic sodium dodecylbenzenesulfonate (SDBS) and the nonionic octaethylene glycol monotetradecyl ether (C
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 11-2021
Publisher: Springer Science and Business Media LLC
Date: 29-04-2014
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Chemical Society (ACS)
Date: 07-08-2022
Publisher: American Chemical Society (ACS)
Date: 15-09-2021
Publisher: Springer Science and Business Media LLC
Date: 05-04-2014
Publisher: Elsevier BV
Date: 09-0011
Publisher: Springer Science and Business Media LLC
Date: 11-07-2015
Publisher: Springer Science and Business Media LLC
Date: 09-12-2016
DOI: 10.1007/S00249-015-1099-5
Abstract: Surfactin, a sustainable and environmentally friendly surface active agent, is used as a model to study the adsorption of biosurfactants at hydrophobic and hydrophilic solid-liquid interfaces as well as the air-liquid interface. Surfactin adsorption was monitored as a function of time and concentration using surface plasmon resonance (SPR) technique in the case of the solid-liquid interfaces or the drop shape analysis (DSA) technique in the case of the air-liquid interface. The results obtained in this study showed that surfactin adsorption at the "hard" hydrophobic (functionalized with octadecanethiol) solid-liquid and the "soft" air-liquid interface were 1.12 ± 0.01 mg m(-2) (area per molecule of 157 ± 2 Å(2)) and 1.11 ± 0.05 mg m(-2) (area per molecule of 159 ± 7 Å(2)), respectively, demonstrating the negligible effect of the interface "hardness" on surfactin adsorption. The adsorption of surfactin at the hydrophilic (functionalized with β-mercaptoethanol) solid-liquid interface was about threefold lower than its adsorption at the hydrophobic-liquid interfaces, revealing the importance of hydrophobic interaction in surfactin adsorption process. The affinity constant of surfactin for the investigated interfaces follows the following order: air > octadecanethiol > β-mercaptoethanol. Biosurfactants, such as surfactin, are expected to replace the conventional fossil-based surfactants in several applications, and therefore the current study is a contribution towards the fundamental understanding of biosurfactant behavior, on a molecular level, at hydrophobic and hydrophilic solid-liquid interfaces in addition to the air-liquid interface. Such understanding might aid further optimization of the utilization of surfactin in a number of industrial applications such as enhanced oil recovery, bioremediation, and detergency.
Publisher: American Chemical Society (ACS)
Date: 13-01-2009
DOI: 10.1021/LA802825C
Abstract: Rationally designed peptide biosurfactant AM1 was mixed with sodium dodecyl benzene sulfonate (SDOBS) to self-assemble a mixed surfactant-biosurfactant layer at the air-water interface. Under optimal conditions in the presence of Zn2+, the interfacial elasticity of the mixed layer was approximately 5-fold higher than for biosurfactant alone. Two head positional isomers, SDOBS-2 and SDOBS-6, were compared for their ability to enhance interfacial film strength. SDOBS-6 forms a stronger layer with AM1 than does SDOBS-2. The highest interfacial elasticity of the AM1/SDOBS-6 layer was 640 mN m(-1) whereas the maximum value for the AM1/SDOBS-2 layer was 440 mN m(-1). Neutron reflection was used to investigate the structure of AM1/SDOBS films at varied bulk SDOBS concentrations. Both deuterated and nondeuterated SDOBS-2 and SDOBS-6 were used to provide contrast variation. It was shown that there is cooperative interaction between AM1 and SDOBS at low SDOBS concentration in the presence of 100 microM Zn2+, promoting AM1 adsorption atthe interface to form a two-layered structure of AM1 resulting in a mechanically strong interfacial film. In the presence of EDTA, only a single AM1 layer was formed at the same SDOBS concentration, and the film did not show lateral force transmission capability. Further increasing the SDOBS concentration to a molar excess of > 10x decreased the peptide population at the interface and resulted in a mechanically weak layer. Compared to SDOBS-6, SDOBS-2 depletes AM1 at a lower bulk concentration. These results demonstrate that the film strength of a self-assembled surfactant-biosurfactant mixed layer can be fine tuned by changing the isomer type and concentration of surfactant and by adding or removing metal ions.
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 15-10-2015
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.COLSURFB.2009.03.015
Abstract: Surface Plasmon Resonance (SPR) and rubisco protein stain were used as tools to screen the effectiveness of detergent formulations in cleaning a protein stain from solid surfaces. Surfactant and biosurfactant-based formulations, with and without added protease, were screened for cleaning performance. Enzyme-free detergent formulations at 1500 ppm total surfactant were insufficient to cause complete surface cleaning, despite the high concentration of surfactant. The cleaning performance of a "home-made" formulation containing 2 ppm subtilisin A (SA) and 2 ppm sodium dodecyl benzyl sulphonate (SDOBS) was as efficient as the best amongst the three enzyme-free 1500 ppm formulations. The cleaning performance of 2 ppm SA in the absence of SDOBS was less effective than the combined formulation, even though 2 ppm SDOBS alone did not cause any protein removal. The observed synergistic performance was attributed to the cooperative mechanisms (chemical and physical attack) by which these two agents act on a rubisco stain. Replacing SDOBS in the enzyme-surfactant formulation with the same amount of surfactin biosurfactant (2 ppm) gave the best rubisco removal of all formulations examined in this study, irrespective of the surface chemistry underlying the protein film. It was found that 75% and 80% of immobilised rubisco stain could be removed from hydrophobic and hydrophilic surfaces, respectively, by the biosurfactant-SA formulation (compared with 60% and 65%, respectively, using the SDOBS-SA formulation). Our results suggest that it may be possible to generate fully renewable biochemical-based cleaning formulations that have superior cleaning performance to existing technologies. In developing optimised formulations, there is a pressing need for chip-based tools similar to that developed in this research.
Publisher: American Chemical Society (ACS)
Date: 07-09-2021
Publisher: Springer Science and Business Media LLC
Date: 30-03-2014
DOI: 10.1007/S00249-014-0955-Z
Abstract: Tethered bilayer lipid membranes (tBLMs) are important tools for studying protein-lipid interactions. The widely used methodology for the preparation of these membranes is the fusion of phospholipid vesicles from an aqueous medium onto an anchored phospholipid layer. The preparation of phospholipid vesicles is a long and tedious procedure. There is another simple method, rapid solvent exchange, for preparing lipid membranes. However, there is a lack of information on the effects of the preparation method of tBLMs on their interactions with proteins. Therefore, we present in this paper a comparative study on the binding of lysozyme onto tBLMs prepared by the abovementioned methods. The prepared tBLMs have either zwitterionic or anionic characteristics. The results show that lysozyme binding onto the prepared tBLMs is unaffected by the preparation method of the tBLMs, suggesting that the tedious fusion method might be replaced by the simple rapid solvent exchange method without altering the level of protein-lipid interactions.
Publisher: Wiley
Date: 27-02-2016
Publisher: Elsevier BV
Date: 12-2012
Publisher: Springer Science and Business Media LLC
Date: 26-02-2019
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.JCIS.2011.04.060
Abstract: Protein-surfactant interaction, which is a function of the protein and surfactant characteristics, is a common phenomenon in a wide range of industrial applications. In this work, we used rubisco, the most abundant protein in nature, as a model protein and sodium dodecylbenzenesulfonate (SDOBS), one of the most widely used commercial surfactants, with two positional isomers (SDOBS-2 and SDOBS-6), as a model surfactant. We first examined the surface tension and the mechanical properties of interfacial mixed rubisco-SDOBS films adsorbed at the air-water interface. The concentration of rubisco in solution was fixed at 0.1 mg mL(-1) while the SDOBS concentration varied from 0 to 150 μM. Both the surface tension and the mechanical strength of the interfacial film decreased with increasing SDOBS concentration. Overall, the surface tension of a rubisco-SDOBS-6 mixture is lower than that of rubisco-SDOBS-2, while the mechanical strength of both systems is similar. Neutron reflection data suggest that rubisco protein is likely denatured at the interface. The populations of rubisco and SDOBS of the mixed systems at the interface were determined by combining non-deuterated and deuterated SDOBS to provide contrast variation. At a low surfactant concentration, SDOBS-6 has a stronger ability to displace rubisco from the air-water interface than SDOBS-2. However, when surfactant concentration reaches 50 μM, SDOBS-2 has a higher population than SDOBS-6, with more rubisco displaced from the interface. The results presented in this work suggest that the extent of protein displacement from the air-water interface, and hence the nature of the protein-surfactant interactions at the interface, are strongly affected by the position of surfactant isomerisation, which might allow the design of formulations for efficient removal of protein stains.
Publisher: Wiley
Date: 09-01-2018
Publisher: Springer Science and Business Media LLC
Date: 09-07-2018
DOI: 10.1007/S00249-018-1320-4
Abstract: Protein fouling is a serious problem in many food, pharmaceutical and household industries. In this work, the removal of rubisco protein fouling from cellulosic surfaces using a protease (subtilisin A) has been investigated experimentally and mathematically. The cellulosic surfaces were prepared using self-assembled monolayers (SAMs) on a surface plasmon resonance biosensor (chip) surface after conjugating cellulose to α-lipoic acid. Rubisco adsorption on the prepared cellulosic SAMs was found to be irreversible, leading to the creation of a tough protein fouling. The heterogeneous enzymatic cleansing of such tough fouling involves enzyme transfer to the surface and the subsequent removal of the rubisco via protease activity. In this work, these two processes were decoupled, allowing enzyme transfer and enzymatic surface reaction to be parameterized separately. Mathematical modeling of the enzymatic cleaning of protein fouling from cellulosic SAMs revealed that enzymatic mobility at the interface is an important factor. The approach presented in this work might be useful in designing better protein fouling-resistant surfaces. It could also be used to guide efforts to screen and gauge the cleaning performance of detergent-enzyme formulations.
Publisher: Elsevier BV
Date: 2011
DOI: 10.1016/J.BIOTECHADV.2010.08.012
Abstract: Antimicrobial peptides (AMPs) are next generation antibiotics which will make excellent coating agents for a myriad of devices because they are far less susceptible to the development of pathogen resistance compared to conventional antibiotics, exhibit rapid and broad-spectrum killing profiles, and are effective at low concentrations. These advantages, however, are compromised upon AMP tethering to solid supports. The effects of peptide-tethering strategies in governing AMP orientation, surface density, flexibility, and activity are reviewed. Understanding AMP structure-function relationship in the tethered conformation will enable rational improvements of immobilisation parameters. Foreseeable challenges in the development of AMP-coated devices such as microbial accumulation on implant surface and the lack of direct biomolecular structure and orientation data of peptides on surfaces are also discussed, and solutions to address these roadblocks are also proposed.
Location: Saudi Arabia
No related grants have been discovered for Sagheer Onaizi.