Mohamed Khairy

Mesoporous NiO nanoarchitectures for electrochemical energy storage: influence of size, porosity, and morphology

The development of flexible, sustainable, and efficient energy storage has recently attracted considerable attention to satisfy the demand for huge energy and power density and meet future societal and environmental needs. Consequently, numerous studies have focused on the design/development of nanomaterials based on mesoporous architectures to improve energy and power densities. We explored how nanoarchitectures in term of morphology, particle size, surface area, and pore size/distribution define energy and power performance. The large-scale production, low-cost manufacturing, and high-performance of supercapacitors based on the microwave-assisted synthesis of mesoporous nickel oxide nanocrystals (NCs) were presented. Mesoporous NiO in various morphologies including nanoslices (NSs) and nanoplatelets (NPLs), were synthesized. The superior electrochemical performance of mesoporous NiO NPLs is related to their unique morphology, size, and pore size distribution, which enhance the diffusion of hydroxide ions through mesoporous networks, i.e. “superhighways”. These characteristics induce the high capacitance and excellent recyclability of NiO NPLs more than NiO NSs. Moreover, the microwave-assisted synthesis enhanced charge storage and stability compared with those prepared through the hydrothermal approach. This approach demonstrates the potential of free-standing NiO NPL electrodes for developing high-performance pseudocapacitors.

Optical mesosensors for monitoring and removal of ultra-trace concentration of Zn(II) and Cu(II) ions from water

Optical captor design is necessary for the controlled development of a technique for detecting and removing heavy and toxic metals from drinking water with high flexibility and low capital cost. We designed chemical mesocaptors for optical separation/extraction and monitoring/detection of Cu(II) and Zn(II) ions from water even at trace concentration levels without a preconcentration process. The mesoporous aluminosilica carriers with three-dimensional (3D) structures, high aluminum content, natural surfaces, and active acid sites strongly induced H-bonding and dispersive interactions with organic moieties, thereby leading to the formation of stable captors without chromophore leaching during the removal assays of Cu(II) and Zn(II) ions. Using such a tailored mesocaptor design, the direct immobilization of these hydrophobic ligands (4,5-diamino-6-hydroxy-2-mercaptopyrimidine and diphenylthiocarbazone) into ordered pore-based aluminasilica monoliths enabled the easy generation and transduction of optical colour signals as a response to metal-to-ligand binding events, even at ultra-trace concentrations (~10(-9) mol dm(-3)) of Cu(II) and Zn(II) ions in drinking water, without the need for sophisticated instruments. Theoretical models have been developed to provide insights into the effect of active site surfaces on the enhancement of the optical removal process in terms of long-term stability, reversibility, and selectivity, hence allowing us to understand the role of mesoscopic geometry and nanoscale pore orientation of mesocaptors better. Generally, this ion-capture model enables the development of a simple and effective technique for effective wastewater treatment and management.

Optical detection/collection of toxic Cd(II) ions using cubic Ia3d aluminosilica mesocage sensors

Optical sensors for selective removal and detection of extremely toxic ions such as cadmium (Cd(II)) in aquatic samples were successfully fabricated via simple strategy. Aluminosilica-based network platforms are used as selective mesopore shape and size carriers in order to fabricate optical sensors through the direct functionalization of α, β, γ, and δ-tetrakis(1-methylpyridinium-4-yl)porphine ρ-toluenesulfonate (TMPyP) moieties without any prior surface modification using silane or thiol agents. In turn, the key advantage of a heretical three-dimensional (3D) cubic Ia3d mesocage is the facile access of target ions such as ion transports and the high affinity responses of TMPyP receptor-Cd(II) analyte binding events, which result in the easy generation and transduction of optical signals even at the trace level of the Cd(II) ion. The optical sensor design-based aluminosilica cages enable the sensitive detection and selective removal of Cd(II) ions even at ultra-trace concentrations of 10(-10)mol/dm(3) with rapid response time (in minutes). This rational strategy is crucial to the development of optical mesocollectors (i.e., probe surface-mounted naked-eye ion-sensor strips) with highly selective Cd(II) ion removal from aqueous water. These new classes of optical mesocollectors exhibit long-term stability and reusability of deleterious Cd(II) ions, which makes them efficient for various analytical applications.

Hierarchical inorganic–organic multi-shell nanospheres for intervention and treatment of lead-contaminated blood

The highly toxic properties, bioavailability, and adverse effects of Pb(2+) species on the environment and living organisms necessitate periodic monitoring and removal whenever possible of Pb(2+) concentrations in the environment. In this study, we designed a novel optical multi-shell nanosphere sensor that enables selective recognition, unrestrained accessibility, continuous monitoring, and efficient removal (on the order of minutes) of Pb(2+) ions from water and human blood, i.e., red blood cells (RBCs). The consequent decoration of the mesoporous core/double-shell silica nanospheres through a chemically responsive azo-chromophore with a long hydrophobic tail enabled us to create a unique hierarchical multi-shell sensor. We examined the efficiency of the multi-shell sensor in removing lead ions from the blood to ascertain the potential use of the sensor in medical applications. The lead-induced hemolysis of RBCs in the sensing/capture assay was inhibited by the ability of the hierarchical sensor to remove lead ions from blood. The results suggest the higher flux and diffusion of Pb(2+) ions into the mesopores of the core/multi-shell sensor than into the RBC membranes. These findings indicate that the sensor could be used in the prevention of health risks associated with elevated blood lead levels such as anemia.

Encapsulation of proteins into tunable and giant mesocage alumina

Protein bioadsorption has rapidly attracted attention partially because of the promising advances in diagnostic assays, sensors, separations, and gene technology. Tunable and giant mesocage alumina cavities (5 nm to 20 nm) show capability in size-selective encapsulation and diffusivity of large proteins into interior pores.

Bioadsorption of proteins on large mesocage-shaped mesoporous alumina monoliths

With the remarkable progress in the field of gene technology, proteins have gained an important function in the field of disease diagnosis and treatment. Protein bioadsorption has drawn increasing attention partly because of the promising advances for diagnostic assays, sensors, separations, and gene technology. Mesocage alumina has a cage-type structure with high surface area and pore volume, exhibiting superior capabilities for protein adsorption. In this study, we report the size-selective adsorption/removal of virtual proteins having different shapes, sizes, functions, and properties, including insulin, HopPmaL domain, lysozyme, galectin-3, β-lactoglobulin, α-1-antitrypsin, α-amylase, and myosin in aqueous water using mesocage alumina. The mesoporous alumina monoliths have unique morphology and physical properties and enhanced protein adsorption characteristics in terms of sample loading capacity and quantity, thereby ensuring a higher concentration of proteins, interior pore diffusivity, and encapsulation in a short period. Thermodynamic analysis shows that protein adsorption on mesocage alumina monoliths is favorable and spontaneous. Theoretical models have been studied to investigate the major driving forces to achieve the most optimal performance of protein adsorption. The development of ultra- or micrometer-scale morphology composed of mesocage-shaped mesoporous monoliths or alumina network clusters can be effectively used to encapsulate the macromolecules into the interior cage cavities, which can greatly assist in other potentials for biomedical applications. Furthermore, the adsorption of a single protein from mixtures based on size- and shape-selective separation can open up new ways to produce micro-objects that suit a given protein encapsulation design.

Mesoporous nanomagnet supercaptors for selective heme-proteins from human cells

Nanomagnet-selective supercaptors of heme-proteins (iron-porphyrin prosthetic group) based on mesoporous NiO and Fe(3)O(4) NPs were fabricated.

Promising supercapacitor electrodes based immobilization of proteins onto macroporous Ni foam materials

Abstract Immobilizing biocomponents on solid surfaces is a critical step in the development of new devices for future biological, medical, and electronic applications. Therefore, numerous integrated films were recently developed by immobilizing different proteins or enzymes on electrode surfaces. In this work, hemeproteins were safely immobilized onto macroporous nickel-based electrodes while maintaining their functionality. Such modified electrodes showed interesting pseudo-capacitive behavior. Among hemeproteins, hemoglobin (Hb) film has a higher electrochemical performance and greater charge/discharge cycling stability than myoglobin (Mb) and cytochrome C (CytC). The heme group in an alkaline medium could induce the formation of superoxides on the electrode surface. These capacitive features of hemeprotein-Ni electrode were related to strong binding sites between hemeproteins and porous Ni electrode, the accumulation of superoxide or radicals on the Ni surface, and facile electron transfer and electrolyte diffusion through the three-dimensional macroporous network. Thus, these new protein-based supercapacitors have potential use in free-standing platform technology for the development of implantable energy-storage devices.

Optical mesoscopic membrane sensor layouts for water-free and blood-free toxicants

Advances in fabrication of mesoscopic membrane sensors with unique structures and morphologies inside anodic alumina membrane (AAM) nanochannels have led to the development of various methods for detecting, visualizing, adsorbing, filtering, and recovering ultra-trace concentrations of toxic metal ions, such as Hg2+ and Pb2+, in water and blood. These often “one-pot” screening methods offer advantages over conventional methods in that they do not require sophisticated instruments or laborious sample preparation. In the present study, we fabricated two mesoscopic membrane sensors for naked-eye detection, recognition, filtration, and recovery of Hg2+ and Pb2+ in biological and environmental samples. These sensors were characterized by the dense immobilization of organic colorants on the mesopore surfaces of silica nanotubes that were constructed using the nanochannels of an AAM as a scaffold. We confirmed that the nanotubes were oriented along the long axis of the AAM nanochannels, open at both ends, and completely and uniformly filled with organic colorants; also, the dense immobilization of the organic colorants did not affect the speed of ion-to-ligand binding events. We used simple, desk-top, flow-through assays to assess the suitability of the developed membrane sensors for detection, removal, and filtration of Hg2+ and Pb2+ with respect to recyclability and continuous monitoring. Removal of the target ions from biological fluids was assessed by means of flow cytometric analysis. Our results demonstrate the potential of our membrane sensors to be used for preventing the health risks associated with exposure to toxic metal ions in the environment and blood.

Trapping of biological macromolecules in the three-dimensional mesocage pore cavities of monolith adsorbents

Gene technology is experiencing remarkable progress, and proteins are becoming crucial in the field of disease diagnosis and treatment. Adsorption of biomolecules on the surface of inorganic materials is an important technique for diagnostic assays and gene applications. In this study, highly ordered mesocage cubic Pm3n aluminumsilica monoliths were fabricated by the one-pot direct-templating of a microemulsion of the liquid crystalline phases of a Brij 56 surfactant. Mesocage cubic Pm3n aluminosilica monoliths with well-defined mesostructures offer high adsorption and loading capacity of proteins from an aqueous solution. Three-dimensional monoliths characterized by spherical pore cavities can potentially perform efficient adsorption and trapping of insulin, cytochrome C, lysozyme, myoglobin, β-lactoglobin proteins. A wide variety of characterization techniques such as SAXS, SEM, TEM, the Brunauer–Emmett–Teller method for nitrogen adsorption and surface area measurements, and TEM were used. The adsorption of proteins as well as the kinetic and thermodynamic characteristics of adsorption was studied, and adsorption isotherms were described by the Langmuir equation. Our findings indicated that monolayer coverage of proteins formed on mesoporous adsorbent surfaces during immobilization and uptake assays. Adsorption efficiency of proteins was attained after a number of reuse cycles, which indicates the presence of mesoporous adsorbents of biomolecules. Integration of mesoporous adsorbents may be feasible in various scientific fields such as nanobioscience, material science, artificial implantation, protein purification, biosensors, drug delivery systems, and molecular biology/biotechnology.