Walaa Alharbi

Dr. Walaa Alharbi


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 January 2022 in Polymers
Verified
Journal Article
Open access
ABAli Bashal
Ali Bashal
SRSayed Riyadh
Sayed Riyadh
WAWalaa Alharbi
Walaa Alharbi
KAKhadijah Alharbi
Khadijah Alharbi
TFThoraya Farghaly
Thoraya Farghaly
Khaled D. KhalilKhaled D. Khalil
Khaled D. Khalil
In recent years, nanotechnology has become a considerable research interest in the area of preparation of nanocatalysts based on naturally occurring polysaccharides. Chitosan (CS), as a naturally occurring biodegradable and biocompatible polysaccharide, is successfully utilized as an ideal template for the immobilization of metal oxide nanoparticles. In this study, zinc oxide nanoparticles have been doped within a chitosan matrix at dissimilar weight percentages (5, 10, 15, 20, and 25 wt.% CS/ZnO) and have been fabricated by using a simple solution casting method. The prepared solutions of the nanocomposites were cast in a Petri-dish and were subsequently shaped as a thin film. After that, the structural features of the nanocomposite film have been studied by measuring the FTIR, SEM, and XRD analytical tools. FTIR spectra showed the presence of some changes in the major characteristic peaks of chitosan due to interaction with ZnO nanoparticles. In addition, SEM graphs exhibited dramatic morphology changes on the chitosan surface, which is attributed to the surface adsorption of ZnO molecules. Based on the results of the investigated organic catalytic reactions, the prepared CS/ZnO nanocomposite film (20 wt.%) could be a viable an effective, recyclable, and heterogeneous base catalyst in the synthesis of thiazoles. The results showed that the nanocomposite film is chemically stable and can be collected and reused in the investigated catalytic reactions more than three times without loss of its catalytic activity.

30 May 2022 in Gels
Verified
Journal Article
Open access
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NANaheed Akhtar
Naheed Akhtar
NANaveed Akhtar
Naveed Akhtar
Farid MenaaFarid Menaa
Farid Menaa
WAWalaa Alharbi
Walaa Alharbi
FAFatima S. Alaryani
Fatima S. Alaryani
FAFaizan Ahmad
Faizan Ahmad
Background: Tocopherol acetate (TA) is known as a skin moisturizing and photoprotective agent. One major drawback with tocopherol and its derivatives remains its limited stability. Aim: To develop highly stable TA-containing ethosomal gel (TAEG) as an advanced dosage form. Methods: A cold method technique was used to produce the ethosomes. An in vitro evaluation of viscosity, conductivity, and pH stability was carried out for three months. An in vitro physical characterization of the nanoparticles (NPs) that included particle size (PS), zeta potential (ZP), transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy analysis was then performed. Organoleptic evaluation, thermostability at 8 °C, 25 °C, 40 °C and 40 °C ± 75% RH, pH, conductivity, viscosity, and spreadability measurements were also performed in vitro for three months. An ex vivo permeation study was performed in phosphate-buffered solution (1× PBS; pH 5.5 or pH 7.4) at 37 ± 0.2 °C by using rat abdominal skin and the Franz diffusion cell method. The data of three independent experiments were expressed as mean ± SD. A two-way ANOVA was applied to compare data on TAEG versus TA control gel (TACG). Results: PS of the ethosomes was in the range of 144–289 nm. A total of nine formulations were developed. Optimized TAEG formulation (TA-5) was selected based on the highest entrapment efficiency (EE) of 99.71%, while the stability, the PS, and the uniformity-based polydispersity index (PDI) were also among the best. TA-5 exhibited smooth spherical ethosomal NPs with PS of 200.6 nm, ZP value of −18.6 V, and PDI of 0.465. Stability data obtained for TA-5 in terms of rheology, conductivity, and pH presented no significant change (p > 0.05) during the entire study duration. Rheological studies indicated that TA-5 followed a non-Newtonian behavior of shear thinning system. The ex vivo drug permeation was 44.55 ± 0.01% in TA-5 and the drug retention in skin was 51.20%, which was significantly higher than TACG as observed after 24 h permeation study (p < 0.05). Conclusions: The newly developed TAEG formulation appears promising to enhance the effectivity of TA and its topical application.

12 July 2022 in Polymers
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Journal Article
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Khaled D. KhalilKhaled D. Khalil
Khaled D. Khalil
SRSayed Riyadh
Sayed Riyadh
NANazeeha suliman alkayal
Nazeeha suliman alkayal
ABAli Bashal
Ali Bashal
KAKhadijah Alharbi
Khadijah Alharbi
WAWalaa Alharbi
Walaa Alharbi
Recently, Strontium oxide (SrO) nanoparticles (NPs) and hybrids outperformed older commercial catalysts in terms of catalytic performance. Herein, we present a microwave-assisted easy in situ solution casting approach for the manufacture of strontium oxide nanoparticles doped within a naturally occurring polymer, chitosan (CS), at varying weight percentages (2.5, 5, 10, 15, and 20 wt.% SrO/chitosan). To construct the new hybrid material as a thin film, the produced nanocomposite solutions were cast in petri dishes. The aim of the research was to synthesize these hybrid nanocomposites, characterize them, and evaluate their catalytic potential in a variety of organic processes. The strontium oxide-chitosan nanocomposites were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. All the results confirmed the formation of chitosan–strontium oxide nanocomposite. FTIR spectrum of nanocomposite showed the presence of a characteristic peak of Sr-O bond. Furthermore, XRD revealed that SrO treatment increased the crystallinity of chitosan. The particle size was calculated using the Debye–Scherrer formula, and it was determined to be around 36 nm. The CS-SrO nanocomposite has been proven to be a highly efficient base promoter for the synthesis of 2-hydrazono [1,3,4]thiadiazole derivatives. To optimize the catalytic method, the reaction factors were investigated. The approach has various advantages, including higher reaction yields, shorter reaction durations, and milder reaction conditions, as well as the catalyst’s reusability for several applications.

28 February 2023 in Polymers
Verified
Journal Article
Open access
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KAKhadijah Alharbi
Khadijah Alharbi
WAWalaa Alharbi
Walaa Alharbi
MEMohamed Abdou El-Morsy
Mohamed Abdou El-Morsy
MFMohammed Farea
Mohammed Farea
AMAbdelrhman Menazea
Abdelrhman Menazea
The polymeric material polyvinyl pyrrolidine/carboxymethyl cellulose (PVP/CMC) was mixed with different quantities of tungsten-trioxide nanoparticles (WO3 NPs). The samples were created using the casting method and Pulsed Laser Ablation (PLA). The manufactured samples were analyzed by utilizing various methods. The halo peak of the PVP/CMC was located at 19.65°, confirming its semi-crystalline nature, as shown in the XRD analysis. FT-IR spectra of pure PVP/CMC composite and PVP/CMC composite incorporated with various contents of WO3 obtained a shift in band locations and change in intensity. Optical band gap was calculated via UV–Vis spectra, which decreased when increasing the laser-ablation time. Thermogravimetric analyses (TGA) curves showed that samples’ thermal stability had improved. The frequency-dependent composite films were used to determine AC conductivity of the generated films. When increasing the content of tungsten-trioxide nanoparticles, both (ε′) and (ε′′) increased. The incorporation of tungsten trioxide enhanced the ionic conductivity of PVP/CMC/WO3 nano-composite to a maximum of 10−8 S/c. It is expected that these studies will have a significant impact on several utilizations, such as energy storage, polymer organic semiconductors, and polymer solar cells.

15 June 2023 in Molecules
Verified
Journal Article
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LRLaila Abdel Rahman
Laila Abdel Rahman
MBMaram Basha
Maram Basha
BABadriah Saad Al-Farhan
Badriah Saad Al-Farhan
WAWalaa Alharbi
Walaa Alharbi
MSMohamed Refaat Shehata
Mohamed Refaat Shehata
DEDoaa Mahmoud Abou El-ezz
Doaa Mahmoud Abou El-ezz
A new chlorobenzylidene imine ligand, (E)-1-((5-chloro-2-hydroxybenzylidene)amino) naphthalen-2-ol (HL), and its [Zn(L)(NO3)(H2O)3], [La(L)(NO3)2(H2O)2], [VO(L)(OC2H5)(H2O)2], [Cu(L)(NO3)(H2O)3], and [Cr(L)(NO3)2(H2O)2], complexes were synthesized and characterized. The characterization involved elemental analysis, FT-IR, UV/Vis, NMR, mass spectra, molar conductance, and magnetic susceptibility measurements. The obtained data confirmed the octahedral geometrical structures of all metal complexes, while the [VO(L)(OC2H5)(H2O)2] complex exhibited a distorted square pyramidal structure. The complexes were found to be thermally stable based on their kinetic parameters determined using the Coats–Redfern method. The DFT/B3LYP technique was employed to calculate the optimized structures, energy gaps, and other important theoretical descriptors of the complexes. In vitro antibacterial assays were conducted to evaluate the complexes’ potential against pathogenic bacteria and fungi, comparing them to the free ligand. The compounds exhibited excellent fungicidal activity against Candida albicans ATCC: 10231 (C. albicans) and Aspergillus negar ATCC: 16404 (A. negar), with inhibition zones of HL, [Zn(L)(NO3)(H2O)3], and [La(L)(NO3)2(H2O)2] three times higher than that of the Nystatin antibiotic. The DNA binding affinity of the metal complexes and their ligand was investigated using UV-visible, viscosity, and gel electrophoresis methods, suggesting an intercalative binding mode. The absorption studies yielded Kb values ranging from 4.40 × 105 to 7.30 × 105 M−1, indicating high binding strength to DNA comparable to ethidium bromide (value 107 M−1). Additionally, the antioxidant activity of all complexes was measured and compared to vitamin C. The anti-inflammatory efficacy of the ligand and its metal complexes was evaluated, revealing that [Cu(L)(NO3)(H2O)3] exhibited the most effective activity compared to ibuprofen. Molecular docking studies were conducted to explore the binding nature and affinity of the synthesized compounds with the receptor of Candida albicans oxidoreductase/oxidoreductase INHIBITOR (PDB ID: 5V5Z). Overall, the combined findings of this work demonstrate the potential of these new compounds as efficient fungicidal and anti-inflammatory agents. Furthermore, the photocatalytic effect of the Cu(II) Schiff base complex/GO was examined.

28 March 2022 in Materials
Verified
Journal Article
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MHMai S. A. Hussien
Mai S. A. Hussien
ABAbdelfatteh Bouzidi
Abdelfatteh Bouzidi
HAHisham Abd-Rabboh
Hisham Abd-Rabboh
IYIbrahim Yahia
Ibrahim Yahia
HZHeba Zahran
Heba Zahran
MIMedhat Ibrahim
Medhat Ibrahim
The incorporation of tungsten trioxide (WO3) by various concentrations of graphitic carbon nitride (g-C3N4) was successfully studied. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and Diffused Reflectance UV-Vis techniques were applied to investigate morphological and microstructure analysis, diffused reflectance optical properties, and photocatalysis measurements of WO3/g-C3N4 photocatalyst composite organic compounds. The photocatalytic activity of incorporating WO3 into g-C3N4 composite organic compounds was evaluated by the photodegradation of both Methylene Blue (MB) dye and phenol under visible-light irradiation. Due to the high purity of the studied heterojunction composite series, no observed diffraction peaks appeared when incorporating WO3 into g-C3N4 composite organic compounds. The particle size of the prepared composite organic compound photocatalysts revealed no evident influence through the increase in WO3 atoms from the SEM characteristic. The direct and indirect bandgap were recorded for different mole ratios of WO3/g-C3N4, and indicated no apparent impact on bandgap energy with increasing WO3 content in the composite photocatalyst. The composite photocatalysts’ properties better understand their photocatalytic activity degradations. The pseudo-first-order reaction constants (K) can be calculated by examining the kinetic photocatalytic activity.