Alaa Adawy | University of Groningen (original) (raw)

Papers by Alaa Adawy

Journal of Applied Polymer Science

Slight modification of the molten salt synthesis of poly(triazine imide) (PTI) with introduction ... more Slight modification of the molten salt synthesis of poly(triazine imide) (PTI) with introduction of copper (I) chloride yielded a novel copper modified material. Energy‐dispersive x‐ray spectroscopy together with electron microscopy confirmed homogenous distribution of the copper within PTI lattice. X‐ray photoelectron spectroscopy suggests the copper to coordinate randomly at bridging nitrogen atoms. Thus obtained material exhibited excellent sensitivity to nitrite anions together with low limits of detection. Under previously optimized experimental conditions and pH 4 of supporting electrolyte, differential pulse voltammetric detection method showed linear response in wide range from 5 to 2200 μM with detection limit of 1.3 μM. Practical applicability for the developed method was scrutinized in wastewater and pipe water samples. Developed method of metal ion intercalation open doors to widespread introduction of metal ions in the PTI structure for practical utilization.

Journal of Solid State Chemistry

Chemical Engineering Journal

The Open Medical Devices Journal, 2009

Symmetry, 2022

Many structures in nature look symmetric, but this is not completely accurate, because absolute s... more Many structures in nature look symmetric, but this is not completely accurate, because absolute symmetry is close to death. Chirality (handedness) is one form of living asymmetry. Chirality has been extensively investigated at different levels. Many rules were coined in attempts made for many decades to have control over the selection of handedness that seems to easily occur in nature. It is certain that if good control is realized on chirality, the roads will be ultimately open towards numerous developments in pharmaceutical, technological, and industrial applications. This tutorial review presents a report on chirality from single molecules to supramolecular assemblies. The realized functions are still in their infancy and have been scarcely converted into actual applications. This review provides an overview for starters in the chirality field of research on concepts, common methodologies, and outstanding accomplishments. It starts with an introductory section on the definitions and classifications of chirality at the different levels of molecular complexity, followed by highlighting the importance of chirality in biological systems and the different means of realizing chirality and its inversion in solid and solution-based systems at molecular and supramolecular levels. Chirality-relevant important findings and (bio-)technological applications are also reported accordingly.

Journal of Materials Chemistry C

A novel two-step procedure based on the carbonization of Ni-based MOF allows the formation of Ni@... more A novel two-step procedure based on the carbonization of Ni-based MOF allows the formation of Ni@C nanoparticles protected against oxidation. Different crystalline structures are formed, but only Ni-FCC is ferromagnetic.

Calcium phosphate phases are among the most widely accepted compounds for biomaterial application... more Calcium phosphate phases are among the most widely accepted compounds for biomaterial applications, of which the resorbable phases have gained particular attention in recent years. Brushite and its anhydrous form monetite are among the most interesting resorbable calcium phosphate phases that can be applied as cements and for in situ fabrication of three-dimensional (3D) implants. Of these two dicalcium phosphate compounds, monetite is more stable and undergoes slower degradation than brushite. The purpose of the current study is to synthesize and dope monetite with the antimicrobial elements silver and zinc and the osteoinductive element strontium and investigate the possible structural variations as well as their biocompatibility and antimicrobial effectiveness. For this, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and cryo-transmission electron microscopy (cryo-TEM) were used to thoroughly study the synthesized structures. Moreover, the ASTM E-2149-01 protocol and a cell proliferation assay were used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) and the cytocompatibility of the different phases with the Soas-2 cell line, respectively. The results confirm the successful synthesis and doping procedures, such that zinc was the most incorporated element into the monetite phase and strontium was the least incorporated element. The microbiological studies revealed that silver is a very effective antimicrobial agent at low concentrations but unsuitable at high concentrations because its cytotoxicity would prevail. On the other hand, doping the compounds with zinc led to a reasonable antimicrobial activity without compromising the biocompatibility to obviously high concentrations. The study also highlights that strontium, widely known for its osteoinductivity, bears an antimicrobial effect at high concentrations. The generated doped compounds could be beneficial for prospective studies as bone cements or for scaffold biomaterial applications.

Acta Crystallographica Section A Foundations and Advances

Synthesizing pharmaceuticals and biomaterials that have antimicrobial biofunctionality has gained... more Synthesizing pharmaceuticals and biomaterials that have antimicrobial biofunctionality has gained an increasing interest. In this respective, silver nanoparticles (AgNPs) possess outstanding antimicrobial activity. Nevertheless, their uncontrolled release in biological media can induce cytotoxic effects. In order to improve their bio-functionality, a number of metal phosphates, based on titanium and zirconium as the metallic sources, belonging to two distinct morphologies: nanolayered and nanofibrous structures were used as reservoirs for AgNPs (Fig.1). Nanolayered α-phases of titanium-and zirconium (IV) phosphates were supplemented with AgNPs. The structural assessment confirmed the stability of the structures and their sizes that laid in the nanoscale at least in one dimension. The cytocompatibility assays confirmed the biocompatibility of the pristine phases and the antimicrobial assays confirmed that both silver-enriched nanolayered structures maintain an antibacterial effect at reasonably low concentrations. The silver release in these layered structures is largely controlled owing to their intercalation [1]. On the other hand, the nanofibrous metal phosphates were utilized through synthesizing two phases of nanostructured titanium phosphate (π and ρ polymorphs). To assess the feasibility of using these nanofibrous π and ρ titanium (IV) phosphate phases for antimicrobial applications, they were enriched with AgNPs. The antimicrobial assays confirmed their functionality as antimicrobial materials. Moreover, the silver release could be controlled through enriching these nanofibrous Ag-enriched structures with strontium that increased their cytocompatibility, as was confirmed using the cytocompatibility and ion-release assessments. As a direct application of these phases for biomaterials applications, Ag-Sr-enriched nanostructured π-titanium phosphate was induced to grow on a commercially available titanium alloy (Ti-6Al-4V), widely used in orthopedic and dental implants. The structural and microscopic observations confirmed the resultant phases and their enrichment with strontium and AgNPs. Analysis of the surface roughness revealed that its values lay at the interface between the nanosized and micro sized topologies [2]. The results altogether demonstrate the feasibility of using the studied (Sr-) Ag-enriched layered and fibrous metal phosphates as bio-functional bone cement/filling or coatings for metallic implants for biomedical applications. Figure 1. SEM images for (a) nanofibrous π-titanium phosphate, (b) nanolayered α-titanium phosphate & (c) α-zirconium phosphate.

Materials Science and Engineering: C, 2021

Biomaterials and their surfaces regulate the biological response and ultimately the quality of he... more Biomaterials and their surfaces regulate the biological response and ultimately the quality of healing at a possible site of implantation. The physical, chemical and topographical properties of implants' surfaces play a decisive role in the biological integration process for their immediate loading and long-term success. Since at this level of biological interaction nano-dimensionality is basically entailed, bio-functional nanostructured composites either as filling/cement or coating to metallic implants are required. This study shows the possibility of synthesizing two phases of nanostructured titanium phosphate (π and ρ polymorphs) and enriching them with silver nanoparticles and strontium. More importantly, Ag-Sr-enriched nanostructured π‑titanium phosphate is induced to grow on a commercially available titanium alloy (Ti-6Al-4V), widely used in orthopedic and dental implants, under highly controlled conditions. Structural and microscopic studies, using XRD, HRTEM and SEM altogether confirm the resultant phases and their enrichment with strontium and silver nanoparticles with an average particle size around 6 nm. Using confocal laser scanning microscopy, the surface roughness was measured and is found to lay at the interface between the nanosized and microsized topologies. Ion release assessments showed that the presence of strontium controlled the release rate of silver ions and this could be beneficial in terms of decreasing the accompanied cytotoxicity that is usually encountered at high concentrations of silver release. Antimicrobial and cell proliferation assays have proved that enriching titanium phosphate with strontium and silver nanoparticles has improved their antimicrobial properties, while the cytotoxicity could be controlled.

Dalton Transactions, 2021

The structure of π-Ti2O(PO4)2·2H2O was determined by the SR-PXRD method. The proton conductivity ... more The structure of π-Ti2O(PO4)2·2H2O was determined by the SR-PXRD method. The proton conductivity of chitosan/π-TiP membranes reached 4.5 × 10−3 S cm−1 at 95%-RH.

Eng, 2022

Metal phosphates represent an important group of materials with established industrial applicatio... more Metal phosphates represent an important group of materials with established industrial applications that are still attracting special scientific interest, owing to their outstanding physical and chemical properties. In this review, we account on the different synthetic routes and applications of zirconium and titanium phosphates, with a special focus on their application in the medicinal field. While zirconium phosphate has been extensively studied and explored with several reported industrial and medicinal applications, especially for drug delivery applications, titanium phosphates have not yet attracted the deserved attention regarding their established applications. However, titanium phosphates have been the focus of several structural studies with their different polymorphic forms, varied chemical structures, and morphologies. These variations introduce titanium phosphates as a strong candidate for technological and, particularly, biomedical applications.

Biosensors and Bioelectronics, 2021

In this work, an unprecedented study exploring the role that slight changes into the Pd/Au propor... more In this work, an unprecedented study exploring the role that slight changes into the Pd/Au proportion have in the electrocatalytic activity of bimetallic Pd-AuNPs toward the oxygen reduction reaction (ORR) is conducted. In particular, a careful control of the amount of Au atoms introduced in the cluster and the evaluation of the optimum Pd:Au ratio for getting the maximum catalytic activity is performed for the first time. First, PdNPs are synthesized by alcohol reduction in the presence of polyvinylpyrrolidone, and gold atoms are selectively introduced on vertex or corner positions of the cluster in different amounts following a galvanic substitution procedure. Average elemental analysis done relying on EDX spectroscopy allows to evaluate the Pd:Au ratio in the Pd-AuNPs obtained. Lineal sweep voltammetry and chronoamperometry are used for the evaluation of the Pd-AuNPs electrocatalytic activity toward ORR at a neutral pH compared to PdNPs and AuNPs alone. Our results indicate that, the synergy between both metals is strongly enhanced when the amount of gold is controlled and occupies the more reactive positions of the cluster, reaching a maximum activity for the NPs containing a 30% of gold, while an excess of this metal leads to a decrease in such activity, as a shelter of the PdNPs is achieved. Chronoamperometric analysis allows the quantification of the optimal Pd-AuNPs at over 6 × 109 NPs/mL levels. Such optimal Pd-AuNPs were used as tags, taking advantage of the bio-functionalities of gold present in the cluster, in a proof-of-concept electrochemical immunosensor for the detection of hyaluronidase wound infection biomarker, using magnetic beads as platforms. Hyaluronidase was detected at levels as low as 50 ng/mL (0.02 U/mL; 437 U/mg) with good reproducibility (RSD below 8%) and selectivity (evaluated against bovine serum albumin, immunoglobulin G and lysozyme). The low matrix effects inherent to the use of magnetic bead platforms allowed us to discriminate between wound exudates with both sterile and infected ulcers without sample pre-treatment. This novel electrocatalytic immunoassay has the advantage, over common methods for NP tags electrochemical detection, of the signal generation in the same neutral medium where the immunoassay takes place (10 mM PBS pH 7.4), avoiding the use of additional and hazardous reagents, bringing it closer to their use as point-of-care devices. Overall, our findings may be of great interest not only for biosensing, but also for applications such as energy converting on fuel cells, in which the ORR has a pivotal role.

Materials, 2021

There is an increasing demand on synthesizing pharmaceuticals and biomaterials that possess antim... more There is an increasing demand on synthesizing pharmaceuticals and biomaterials that possess antimicrobial and/or antiviral activities. In this respective silver nanoparticles are known for their excellent antimicrobial activity. Nevertheless, their uncontrolled release in a biological medium can induce a cytotoxic effect. For this, we explored the use of nanolayered metal phosphates based on titanium and zirconium as materials that can be enriched with silver nanoparticles. Employing the hydrothermal route, crystalline α-phases of zirconium and titanium phosphates (α-ZrP, α-TiP) were synthesized and there after surface-enriched with silver nanoparticles. The structural assessment confirmed the stability of the structures and their sizes are in the nanoscale at least in one dimension. The cytocompatibility assays confirmed the biocompatibility of the pristine phases and the antimicrobial assay confirmed that both silver-enriched nanolayered structures maintain an antibacterial effect...

Minerals, 2020

The aim of this study was to investigate the efficiency of removing Cr6+ from aqueous solutions u... more The aim of this study was to investigate the efficiency of removing Cr6+ from aqueous solutions using two exfoliated vermiculite: (1) heated abruptly at 1000 °C and (2) irradiated with microwave radiation. The effects investigated were contact time, adsorbate concentration and initial Cr6+ concentration. The adsorption with both exfoliated vermiculites was well described by the DKR isotherm, indicative of a cooperative process and with the pseudo second order kinetic model. The Kd value for the two exfoliated vermiculites was similar, 0.2 ·1010 μg/Kg. The maximum adsorption capacity of Cr6+ with thermo-exfoliated vermiculite, 2.81 mol/g, was much higher than with microwave irradiated vermiculite, 0.001 mol/g; both values were obtained with 0.5 g of vermiculite in contact with distilled water enriched with 1 ppm of Cr6+ for 24 h. Factors such as ion chemistry, the solution pH and ionic strength, influence the values of capacity, adsorption energy and initial adsorption rate values of...

Journal of Applied Polymer Science

Journal of Solid State Chemistry

Chemical Engineering Journal

The Open Medical Devices Journal, 2009

Symmetry, 2022

Journal of Materials Chemistry C

Acta Crystallographica Section A Foundations and Advances

Materials Science and Engineering: C, 2021

Dalton Transactions, 2021

Eng, 2022

Biosensors and Bioelectronics, 2021

Materials, 2021

Minerals, 2020

Macromolecular crystallography is the most direct and accurate approach to determine the three-di... more Macromolecular crystallography is the most direct and accurate approach to determine the three-dimensional structure of biological macromolecules. The growth of high quality single crystals, yielding diffraction to the highest X-ray resolution, remains a bottleneck in this methodology. Many methods have been developed to achieve convection-free crystal growth. Unfortunately, they are either very expensive or methodologically demanding. Recently, we showed that diffusion-limited crystal growth can be effectuated in a rather cheap, simple and easily applicable method. Using this “ceiling crystallization method”, an entirely convection-free crystallization environment is achieved, which enhances the purity and crystallinity of protein crystals. The effectiveness of the ceiling method was validated by visual inspection of the morphology of the ceiling crystals as well as by diffraction experiments. We achieved record X-ray resolution for a number of proteins. In addition, the convection...

The growth of high quality single protein crystals, yielding the highest X-ray resolution, remain... more The growth of high quality single protein crystals, yielding the highest X-ray resolution, remains a bottleneck in the macromolecular crystallography. Here we show an entirely convection-free crystallization environment, which enhances the purity and crystallinity of protein crystals. This is accomplished by using an upside-down geometry, where crystals grow at the “ceiling” of a growth-cell completely filled with the crystallization solution. The “ceiling crystals” experience the same diffusion-limited conditions as in space microgravity experiments. The new method was tested on a number of proteins and, the ceiling crystals diffracted X-rays to resolution limits beyond their current world records, even while commercial preparations of sub-optimal purity were used. This also demonstrates the intrinsic purification effect of the ceiling crystallization method.

Macromolecular crystallography is the most direct and accurate approach to determine the three-di... more Macromolecular crystallography is the most direct and accurate approach to determine the three-dimensional functional structure of biological macromolecules. The growth of high quality single crystals, yielding the highest X-ray resolution, remains a bottleneck in this methodology. Gravity-driven convection is hold responsible for interfering with the growth of perfect crystals in all terrestrial methods, while space microgravity provides diffusive mass transport which can improve the quality of protein crystals. Here we show that through an efficient modification of the batch crystallization method, an entirely convection-free crystallization environment is achieved, which enhances the purity and crystallinity of protein crystals. In this novel method, dubbed “Ceiling Crystallization Method”, we exploit gravity to achieve diffusion-limited crystal growth in a terrestrial setting instead of eliminating it. Protein crystals grow at the “ceiling” of a growth-cell experience the same e...

Acta Crystallographica Section A Foundations of Crystallography, 2012

The merits of nanotechnology are reviewed in terms of their medical applications. The essential p... more The merits of nanotechnology are reviewed in terms of their medical applications. The essential physical and medical concepts related to biomaterials are stated. The therapeutic and diagnostic applications of biomaterials at the nanoscale are reviewed as well as some of the very recent novel contributions. Special attention is given to the functionalized biomimetic coating of metallic implants and the novel use of noble nanoparticles in these applications. Exploiting molecular modelling for these applications is also enclosed with examples.