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Fulltext Recent Advances in Graphene-Based Nanocomposites for Ammonia Detection

M Hizam SM, Al-Dhahebi AM, Mohamed Saheed MS

Polymers (Basel), 2022 Nov 24;14(23).
PMID: 36501520 DOI: 10.3390/polym14235125

The increasing demand to mitigate the alarming effects of the emission of ammonia (NH3) on human health and the environment has highlighted the growing attention to the design of reliable and effective sensing technologies using novel materials and unique nanocomposites with tunable functionalities. Among the state-of-the-art ammonia detection materials, graphene-based polymeric nanocomposites have gained significant attention. Despite the ever-increasing number of publications on graphene-based polymeric nanocomposites for ammonia detection, various understandings and information regarding the process, mechanisms, and new material components have not been fully explored. Therefore, this review summarises the recent progress of graphene-based polymeric nanocomposites for ammonia detection. A comprehensive discussion is provided on the various gas sensor designs, including chemiresistive, Quartz Crystal Microbalance (QCM), and Field-Effect Transistor (FET), as well as gas sensors utilising the graphene-based polymer nanocomposites, in addition to highlighting the pros and cons of graphene to enhance the performance of gas sensors. Moreover, the various techniques used to fabricate graphene-based nanocomposites and the numerous polymer electrolytes (e.g., conductive polymeric electrolytes), the ion transport models, and the fabrication and detection mechanisms of ammonia are critically addressed. Finally, a brief outlook on the significant progress, future opportunities, and challenges of graphene-based polymer nanocomposites for the application of ammonia detection are presented.
Core-Shell Vanadium Modified Titania@β-In2S3 Hybrid Nanorod Arrays for Superior Interface Stability and Photochemical Activity

Mumtaz A, Mohamed NM, Mazhar M, Ehsan MA, Mohamed Saheed MS

ACS Appl Mater Interfaces, 2016 Apr 13;8(14):9037-49.
PMID: 26852779 DOI: 10.1021/acsami.5b10147

Core-shell rutile TiO2@β-In2S3 and modified V-TiO2@β-In2S3 were synthesized to develop bilayer systems to uphold charge transport via an effective and stable interface. Morphological studies revealed that β-In2S3 was deposited homogeneously on V-TiO2 as compared to unmodified TiO2 nanorod arrays. X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrometry studies verified the presence of various oxidation states of vanadium in rutile TiO2 and the vanadium surface was utilized for broadening the charge collection centers in host substrate layer and hole quencher window. Subsequently, X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectra confirmed the rutile phases of TiO2 and modified V-TiO2 along with the phases of crystalline β-In2S3. XPS valence band study explored the interaction of valence band quazi Fermi levels of β-In2S3 with the conduction band quazi Fermi levels of modified V-TiO2 for enhanced charge collection at the interface. Photoelectrochemical studies show that the photocurrent density of V-TiO2@β-In2S3 is 1.42 mA/cm(2) (1.5AM illumination). Also, the frequency window for TiO2 was broadened by the vanadium modification in rutile TiO2 nanorod arrays, and the lifetime of the charge carrier and stability of the interface in V-TiO2@β-In2S3 were enhanced compared to the unmodified TiO2@β-In2S3. These findings highlight the significance of modifications in host substrates and interfaces, which have profound implications on interphase stability, photocatalysis and solar-fuel-based devices.
Fulltext MXene Surface on Multiple Junction Triangles for Determining Osteosarcoma Cancer Biomarker by Dielectrode Microgap Sensor

Zhou D, Gopinath SCB, Mohamed Saheed MS, Siva Sangu S, Lakshmipriya T

Int J Nanomedicine, 2020;15:10171-10181.
PMID: 33363373 DOI: 10.2147/IJN.S284752

Background: In recent years, nanomaterials have justified their dissemination for biosensor application towards the sensitive and selective detections of clinical biomarkers at the lower levels. MXene is a two-dimensional layered transition metal, attractive for biosensing due to its chemical, physical and electrical properties along with the biocompatibility.
Materials and Methods: This work was focused on diagnosing osteosarcoma (OS), a common bone cancer, on MXene-modified multiple junction triangles by dielectrode sensing. Survivin protein gene is highly correlated with OS, identified on this sensing surface. Capture DNA was immobilized on MXene by using 3-glycidoxypropyltrimethoxysilane as an amine linker and duplexed by the target DNA sequence.
Results: The limitation and sensitivity of detection were found as 1 fM with the acceptable regression co-efficient value (y=1.0037⨰ + 0.525; R2=0.978) and the current enhancement was noted when increasing the target DNA concentrations. Moreover, the control sequences of single- and triple-mismatched and noncomplementary to the target DNA sequences failed to hybridize on the capture DNA, confirming the specificity. In addition, different batches were prepared with capture probe immobilized sensing surfaces and proved the efficient reproducibility.
Conclusion: This microgap device with Mxene-modified multiple junction triangles dielectrode surface is beneficial to quantify the survivin gene at its lower level and diagnosing OS complication levels.
Nanoscaled Surface Modification of Poly(dimethylsiloxane) Using Carbon Nanotubes for Enhanced Oil and Organic Solvent Absorption

Ong CC, Sundera Murthe S, Mohamed NM, Perumal V, Mohamed Saheed MS

ACS Omega, 2018 Nov 30;3(11):15907-15915.
PMID: 31458235 DOI: 10.1021/acsomega.8b01566

This article demonstrates a novel nanoscale surface modification method to enhance the selectivity of porous poly(dimethylsiloxane) (PDMS) in removing oil from water. The surface modification method is simple and low cost by using sugar as a sacrificial template for temporal adhering of carbon nanotubes (CNT) before addition of PDMS prepolymer to encapsulate the CNT on its surface once polymerized. The PDMS-CNT demonstrated a tremendous increase in absorption capacity up to 3-fold compared to previously reported absorbents composed solely of PDMS. Besides showcasing excellent absorption capacity, the PDMS-CNT also shows a faster absorption rate (25 s) as compared to that of pure PDMS (40 s). The enhanced absorption rate is due to the incorporation of CNT, which roughens the surface of the polymer at the nanoscale and lowers the surface energy of porous PDMS while at the same time increasing the absorbent hydrophobicity and oleophilicity. This property makes the absorbent unique in absorbing only oil but repelling water at the same time. The PDMS-CNT is an excellent absorbent material with outstanding recyclability and selectivity for removing oil from water.
Fulltext Magnetically recoverable magnetite-reduced graphene oxide as a demulsifier for surfactant stabilized crude oil-in-water emulsion

Yau XH, Khe CS, Mohamed Saheed MS, Lai CW, You KY, Tan WK

PLoS One, 2020;15(4):e0232490.
PMID: 32353051 DOI: 10.1371/journal.pone.0232490

Oily wastewater, especially water-oil emulsion has become serious environmental issue and received global attention. Chemical demulsifiers are widely used to treat oil-water emulsion, but the toxicity, non-recyclable and non-environmental friendly characteristic of chemical demulsifiers had limited their practical application in oil-water separation. Therefore, it is imperative to develop an efficient, simple, eco-friendly and recyclable demulsifiers for breaking up the emulsions from the oily wastewater. In this study, a magnetic demulsifier, magnetite-reduced graphene oxide (M-rGO) nanocomposites were proposed as a recyclable demulsifier to break up the surfactant stabilized crude oil-in-water (O/W) emulsion. M-rGO nanocomposites were prepared via in situ chemical synthesis by using only one type Fe salt and GO solid as precursor at room temperature. The prepared composites were fully characterized by various techniques. The effect of demulsifier dosage and pH of emulsion on demulsification efficiency (ED) has been studied in detailed. The demulsification mechanism was also proposed in this study. Results showed that M-rGO nanocomposites were able to demulsify crude O/W emulsion. The ED reaches 99.48% when 0.050 wt.% of M-rGO nanocomposites were added to crude O/W emulsion (pH = 4). Besides, M-rGO nanocomposites can be recycled up to 7 cycles without showing a significant change in terms of ED. Thus, M-rGO nanocomposite is a promising demulsifier for surfactant stabilized crude O/W emulsion.
Fulltext Mechanical Performance and Corrosion Behaviour of Diffusion-Bonded A5083 Aluminium and A36 Mild Steel with Gallium Interlayer

Ismail A, Othman NH, Mustapha M, Mohamed Saheed MS, Abdullah Z, Muhammed M, et al.

Materials (Basel), 2022 Sep 13;15(18).
PMID: 36143643 DOI: 10.3390/ma15186331

This article investigated the mechanical performance and corrosion behaviour of a diffusion-bonded A5083 aluminium/A36 mild steel dissimilar joint with a Gallium (Ga) interlayer. The bonding parameters were the bonding temperature (525 and 550 °C), holding time (60 and 120 min) and surface roughness (800 and 1200 grit). Property characterisation was achieved using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis, Vickers microhardness tester, Izod impact tester and potentiodynamic polarisation testing. The results revealed that the significance of the bonding parameters was in the order bonding temperature > surface roughness > holding time. Increasing the bonding temperature resulted in an increase in the impact strength and a corresponding reduction in the corrosion rate and microhardness. However, increasing the grit size decreased the microhardness and a corresponding increase in the impact strength and corrosion rate. The impact strength and corrosion rate decreased with the increasing holding time while the microhardness followed a reverse trend. It was also discovered that incorporating the Ga interlayer resulted in a 67.9% improvement in the degradation rate.
Interconnected CoNi-Se Hollow Flakes through Reduced Graphene Oxide Sheets as a Cathode Material for Hybrid Supercapacitors

Aboelazm E, Khe CS, Chong KF, Mohamed Saheed MS, Hegazy MBZ

ACS Appl Mater Interfaces, 2024 Mar 27;16(12):15011-15022.
PMID: 38471069 DOI: 10.1021/acsami.3c17615

Achieving a high energy density and long-cycle stability in energy storage devices demands competent electrochemical performance, often contingent on the innovative structural design of materials under investigation. This study explores the potential of transition metal selenide (TMSe), known for its remarkable activity, electronic conductivity, and stability in energy storage and conversion applications. The innovation lies in constructing hollow structures of binary metal selenide (CoNi-Se) at the surface of reduced graphene oxide (rGO) arranged in a three-dimensional (3D) morphology (CoNi-Se/rGO). The 3D interconnected rGO architecture works as a microcurrent collector, while porous CoNi-Se sheets originate the active redox centers. Electrochemical analysis of CoNi-Se/rGO based-electrode reveals a distinct faradic behavior, thereby resulting in a specific capacitance of 2957 F g-1 (1478.5 C g-1), surpassing the bare CoNi-Se with a value of 2149 F g-1 (1074.5 C g-1) at a current density of 1 A g-1. Both materials exhibit exceptional high-rate capabilities, retaining 83% of capacitance at 10 A g-1 compared to 1 A g-1. In a two-electrode coin cell system, the device achieves a high energy density of 73 Wh kg-1 at a power density of 1500 W kg-1, stating an impressive 90.4% capacitance retention even after enduring 20,000 cycles. This study underscores the CoNi-Se/rGO composite's promise as a superior electrode material for high-performance energy storage applications.
Conventional and emerging technologies for removal of antibiotics from wastewater

Phoon BL, Ong CC, Mohamed Saheed MS, Show PL, Chang JS, Ling TC, et al.

J Hazard Mater, 2020 12 05;400:122961.
PMID: 32947727 DOI: 10.1016/j.jhazmat.2020.122961

Antibiotics and pharmaceuticals related products are used to enhance public health and quality of life. The wastewater that is produced from pharmaceutical industries still contains noticeable amount of antibiotics, and this has remained one of the major environmental problems facing public health. The conventional wastewater remediation approach employed by the pharmaceutical industries for the antibiotics wastewater removal is unable to remove the antibiotics completely. Besides, municipal and livestock wastewater also contain unmetabolized antibiotics released by human and animal, respectively. The antibiotic found in wastewater leads to antibiotic resistance challenges, also emergence of superbugs. Currently, numerous technological approaches have been developed to remove antibiotics from the wastewater. Therefore, it was imperative to critically review the weakness and strength of these current advanced technological approaches in use. Besides, the conventional methods for removal of antibiotics such as Klavaroti et al., Homem and Santos also discussed. Although, membrane treatment is discovered as the ultimate choice of approach, to completely remove the antibiotics, while the filtered antibiotics are still retained on the membrane. This study found, hybrid processes to be the best solution antibiotics removal from wastewater. Nevertheless, real-time monitoring system is also recommended to ascertain that, wastewater is cleared of antibiotics.
Gold-Nanohybrid Biosensors for Analyzing Blood Circulating Clinical Biomacromolecules: Current Trend toward Future Remote Digital Monitoring

Letchumanan I, Gopinath SCB, Md Arshad MK, Mohamed Saheed MS, Perumal V, Voon CH, et al.

Crit Rev Anal Chem, 2020 Sep 08.
PMID: 32897761 DOI: 10.1080/10408347.2020.1812373

Mortality level is worsening the situation worldwide thru blood diseases and greatly jeopardizes the human health with poor diagnostics. Due to the lack of successful generation of early diagnosis, the survival rate is currently lower. To overcome the present hurdle, new diagnostic methods have been choreographed for blood disease biomarkers analyses with the conjunction of ultra-small ideal gold nanohybrids. Gold-hybrids hold varieties of unique features, such as high biocompatibility, increased surface-to-volume ratio, less-toxicity, ease in electron transfer and have a greater localized surface plasmon resonance. Gold-nanocomposites can be physically hybrid on the sensor surface and functionalize with the biomolecules using appropriate chemical conjugations. Revolutionizing biosensor platform can be prominently linked for the nanocomposite applications in the current research on medical diagnosis. This review encloses the new developments in diagnosing blood biomarkers by utilizing the gold-nanohybrids. Further, the current state-of-the-art and the future envision with digital monitoring for facile telediagnosis were narrated.