Displaying publications 1 - 20 of 37 in total

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  1. A review of gas chromatographic techniques for identification of aqueous amine degradation products in carbonated environments
    Saeed IM, Mazari SA, Alaba P, Ali BS, Jan BM, Basirun WJ, et al.
    Environ Sci Pollut Res Int, 2021 Feb;28(6):6324-6348.
    PMID: 33398750 DOI: 10.1007/s11356-020-11753-5
    Degradation of amines is a significant issue allied to amine-based carbon dioxide (CO2) absorption in post-combustion CO2 capture. It becomes essential to have a detailed understanding of degradation products for advanced post-combustion CO2 capture technology. Identification and quantification of degradation products of amines help in practicability and environmental assessment of amine-based technology. Gas, liquid, and ion chromatographic techniques are the benchmark tools for qualitative and quantitative analyses of the amines and their derivatives. Among others, gas chromatography has been more in use for this specific application, especially for the identification of degradation products of amines. This review focuses on the critical elucidation of gas chromatographic analysis and development of methods to determine the amine degradation products, highlighting preparation methods for samples and selecting columns and detectors. The choice of detector, column, sample preparation, and method development are reviewed in this manuscript, keeping in view the industry and research applications. Furthermore, obtained results on the quantitative and qualitative analyses using gas chromatography are summarized with future perspectives.
  2. Advancements in electrochemical DNA sensor for detection of human papilloma virus - A review
    Rasouli E, Shahnavaz Z, Basirun WJ, Rezayi M, Avan A, Ghayour-Mobarhan M, et al.
    Anal Biochem, 2018 09 01;556:136-144.
    PMID: 29981317 DOI: 10.1016/j.ab.2018.07.002
    Human papillomavirus (HPV) is one of the most common sexually transmitted disease, transmitted through intimate skin contact or mucosal membrane. The HPV virus consists of a double-stranded circular DNA and the role of HPV virus in cervical cancer has been studied extensively. Thus it is critical to develop rapid identification method for early detection of the virus. A portable biosensing device could give rapid and reliable results for the identification and quantitative determination of the virus. The fabrication of electrochemical biosensors is one of the current techniques utilized to achieve this aim. In such electrochemical biosensors, a single-strand DNA is immobilized onto an electrically conducting surface and the changes in electrical parameters due to the hybridization on the electrode surface are measured. This review covers the recent developments in electrochemical DNA biosensors for the detection of HPV virus. Due to the several advantages of electrochemical DNA biosensors, their applications have witnessed an increased interest and research focus nowadays.
  3. Bioglass® 45S5-based composites for bone tissue engineering and functional applications
    Rizwan M, Hamdi M, Basirun WJ
    J Biomed Mater Res A, 2017 Nov;105(11):3197-3223.
    PMID: 28686004 DOI: 10.1002/jbm.a.36156
    Bioglass® 45S5 (BG) has an outstanding ability to bond with bones and soft tissues, but its application as a load-bearing scaffold material is restricted due to its inherent brittleness. BG-based composites combine the amazing biological and bioactive characteristics of BG with structural and functional features of other materials. This article reviews the composites of Bioglass® in combination with metals, ceramics and polymers for a wide range of potential applications from bone scaffolds to nerve regeneration. Bioglass® also possesses angiogenic and antibacterial properties in addition to its very high bioactivity; hence, composite materials developed for these applications are also discussed. BG-based composites with polymer matrices have been developed for a wide variety of soft tissue engineering. This review focuses on the research that suggests the suitability of BG-based composites as a scaffold material for hard and soft tissues engineering. Composite production techniques have a direct influence on the bioactivity and mechanical behavior of scaffolds. A detailed discussion of the bioactivity, in vitro and in vivo biocompatibility and biodegradation is presented as a function of materials and its processing techniques. Finally, an outlook for future research is also proposed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3197-3223, 2017.
  4. Fulltext Catalytic activity of ethylbenzene with product selectivity by gold nanoparticles supported on zinc oxide
    Anwar A, Ma'amor A, Mahmud HNME, Basirun WJ, Abdullah I
    Turk J Chem, 2022;46(3):730-746.
    PMID: 37720623 DOI: 10.55730/1300-0527.3363
    The oxidation of ethylbenzene (EB) using tert-butyl hydroperoxide as the oxidizing agent was carried out in presence of gold nanoparticles (3 nm) supported on zinc oxide in acetonitrile solution. A higher selectivity towards acetophenone (ACP) as the major product, and a moderate selectivity towards other products such as 1-phenylethanol (PE), benzaldehyde (BZL), and benzoic acid (BzA) were observed using the prepared Au/ZnO nanocatalysts at 100 °C for 24 h. It is suggested the reaction produces an intermediate product, which is dimethylethyl-1-phenylethyl peroxide through a radical mechanism. A small amount of benzaldehyde was observed because benzaldehyde went autoxidation to form benzoic acid with the presence of oxidation agent of TBHP during reaction. The factors affecting the catalytic activity such as gold loading, calcination treatment at 300°C, type of solvent, reaction time, reaction temperature, oxidant to substrate molar ratio, catalyst weight, and solvent volume were studied. The gold nanoparticle catalyst synthesized by deposition precipitation method using urea was characterized by XRD, HRTEM, ATR-IR, XRF, and BET and offers a very selective reaction pathway for the oxidation of ethylbenzene.
  5. Characterization of nickel-doped biphasic calcium phosphate/graphene nanoplatelet composites for biomedical application
    Baradaran S, Moghaddam E, Nasiri-Tabrizi B, Basirun WJ, Mehrali M, Sookhakian M, et al.
    Mater Sci Eng C Mater Biol Appl, 2015 Apr;49:656-668.
    PMID: 25686995 DOI: 10.1016/j.msec.2015.01.050
    The effect of the addition of an ionic dopant to calcium phosphates for biomedical applications requires specific research due to the essential roles played in such processes. In the present study, the mechanical and biological properties of Ni-doped hydroxyapatite (HA) and Ni-doped HA mixed with graphene nanoplatelets (GNPs) were evaluated. Ni (3wt.% and 6wt.%)-doped HA was synthesized using a continuous precipitation method and calcined at 900°C for 1h. The GNP (0.5-2wt.%)-reinforced 6% Ni-doped HA (Ni6) composite was prepared using rotary ball milling for 15h. The sintering process was performed using hot isostatic pressing at processing conditions of 1150°C and 160MPa with a 1-h holding time. The results indicated that the phase compositions and structural features of the products were noticeably affected by the Ni and GNPs. The mechanical properties of Ni6 and 1.5Ni6 were increased by 55% and 75% in hardness, 59% and 163% in fracture toughness and 120% and 85% in elastic modulus compared with monolithic HA, respectively. The in-vitro biological behavior was investigated using h-FOB osteoblast cells in 1, 3 and 5days of culture. Based on the osteoblast results, the cytotoxicity of the products was indeed affected by the Ni doping. In addition, the effect of GNPs on the growth and proliferation of osteoblast cells was investigated in Ni6 composites containing different ratios of GNPs, where 1.5wt.% was the optimum value.
  6. Fulltext Corrosion inhibition properties of pyrazolylindolenine compounds on copper surface in acidic media
    Ebadi M, Basirun WJ, Khaledi H, Ali HM
    Chem Cent J, 2012 Dec 31;6(1):163.
    PMID: 23276247 DOI: 10.1186/1752-153X-6-163
    BACKGROUND: The corrosion inhibition performance of pyrazolylindolenine compounds, namely 4-(3,3-dimethyl-3H-indol-2-yl)-pyrazole-1-carbothioamide (InPzTAm), 4-(3,3-dimethyl-3H-indol-2-yl)-1H-pyrazole-1-carbothiohydrazide (InPzTH) and 3,3-dimethyl-2-(1-phenyl-1H-pyrazol-4-yl)-3H-indole (InPzPh),) on copper in 1M HCl solution is investigated by electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and linear scan voltammetry (LSV) techniques.

    RESULTS: The results show that the corrosion rate of copper is diminished by the compounds with the inhibition strength in the order of: InPzTAm> InPzTH > InPzPh. The corrosion inhibition efficiencies for the three inhibitors are 94.0, 91.4 and 79.3, for InPzTAm, InPzTH and InPzPh respectively with the same inhibitor concentration (2 mM).

    CONCLUSION: From the EIS, OCP and LSV results it was concluded that pyrazolylindolenine compounds with S-atom (with an amine group) have illustrated better corrosion inhibition performance compared to hydrazine and phenyl group.

  7. DNA/Nano based advanced genetic detection tools for authentication of species: Strategies, prospects and limitations
    Khalil I, Hashem A, Nath AR, Muhd Julkapli N, Yehye WA, Basirun WJ
    Mol Cell Probes, 2021 10;59:101758.
    PMID: 34252563 DOI: 10.1016/j.mcp.2021.101758
    Authentication, detection and quantification of ingredients, and adulterants in food, meat, and meat products are of high importance these days. The conventional techniques for the detection of meat species based on lipid, protein and DNA biomarkers are facing challenges due to the poor selectivity, sensitivity and unsuitability for processed food products or complex food matrices. On the other hand, DNA based molecular techniques and nanoparticle based DNA biosensing strategies are gathering huge attention from the scientific communities, researchers and are considered as one of the best alternatives to the conventional strategies. Though nucleic acid based molecular techniques such as PCR and DNA sequencing are getting greater successes in species detection, they are still facing problems from its point-of-care applications. In this context, nanoparticle based DNA biosensors have gathered successes in some extent but not to a satisfactory stage to mark with. In recent years, many articles have been published in the area of progressive nucleic acid-based technologies, however there are very few review articles on DNA nanobiosensors in food science and technology. In this review, we present the fundamentals of DNA based molecular techniques such as PCR, DNA sequencing and their applications in food science. Moreover, the in-depth discussions of different DNA biosensing strategies or more specifically electrochemical and optical DNA nanobiosensors are presented. In addition, the significance of DNA nanobiosensors over other advanced detection technologies is discussed, focusing on the deficiencies, advantages as well as current challenges to ameliorate with the direction for future development.
  8. Discovery of indoleninyl-pyrazolo[3,4-b]pyridines as potent chemotherapeutic agents against colorectal cancer cells
    Basir NH, Ramle AQ, Ng MP, Tan CH, Tiekink ERT, Sim KS, et al.
    Bioorg Chem, 2024 May;146:107256.
    PMID: 38460334 DOI: 10.1016/j.bioorg.2024.107256
    A new series of indolenines decorated with pyrazolo[3,4-b]pyridines were designed and synthesized in up to 96% yield from the acid-catalyzed cyclocondensation of 1,3-dialdehydes with 3-aminopyrazoles. X-ray crystallography on a representative derivative, 5n, revealed two close to planar conformations whereby the N-atom of the pyridyl residue was syn or anti to the pyrrole-N atom in the two independent molecules of the asymmetric unit. The computational and DNA binding data suggest that 5n is a strong DNA intercalator with the results in agreement with its potent cytotoxicity against two colorectal cancer cell lines (HCT 116 and HT-29). In contrast to doxorubicin, compounds 5k-o have higher druggability (compliance to more criteria stated in Lipinski's rule of five and Veber's rule), higher bioavailability, and better medicinal chemistry properties, indicative of their potential application as chemotherapeutical agents.
  9. Dual platform based sandwich assay surface-enhanced Raman scattering DNA biosensor for the sensitive detection of food adulteration
    Khalil I, Yehye WA, Muhd Julkapli N, Sina AA, Rahmati S, Basirun WJ, et al.
    Analyst, 2020 Feb 17;145(4):1414-1426.
    PMID: 31845928 DOI: 10.1039/c9an02106j
    Surface enhanced Raman scattering (SERS) DNA biosensing is an ultrasensitive, selective, and rapid detection technique with the ability to produce molecule-specific distinct fingerprint spectra. It supersedes the long amplicon based PCR assays, the fluorescence and spectroscopic techniques with their quenching and narrow spectral bandwidth, and the electrochemical detection techniques using multiplexing. However, the performance of the SERS DNA biosensor relies on the DNA probe length, platform composition, both the presence and position of Raman tags and the chosen sensing strategy. In this context, we herein report a SERS biosensor based on dual nanoplatforms with a uniquely designed Raman tag (ATTO Rho6G) intercalated short-length DNA probe for the sensitive detection of the pig species Sus scrofa. In the design of the signal probe (SP), a Raman tag was incorporated adjacent to the spacer arm, followed by a terminal thiol modifier, which consequently had a strong influence on the SERS signal enhancement. The detection strategy involves the probe-target DNA hybridization mediated coupling of the two platforms, i.e., the graphene oxide-gold nanorod (GO-AuNR) functionalized capture probe (CP) and SP-conjugated gold nanoparticles (AuNPs), consequently enhancing the SERS intensity by both the electromagnetic hot spots generated at the junctions or interstices of the two platforms and the chemical enhancement between the AuNPs and the adsorbed intercalated Raman tag. This dual platform based SERS DNA biosensor exhibited outstanding sensitivity in detecting pork DNA with a limit of detection (LOD) of 100 aM validated with DNA extracted from a pork sample (LOD 1 fM). Moreover, the fabricated SERS biosensor showed outstanding selectivity and specificity for differentiating the DNA sequences of six closely related non-target species from the target DNA sequences with single and three nucleotide base-mismatches. Therefore, the developed short-length DNA linked dual platform based SERS biosensor could replace the less sensitive traditional methods of pork DNA detection and be adopted as a universal detection approach for the qualitative and quantitative detection of DNA from any source.
  10. Electrochemical assisted enhanced nanozymatic activity of functionalized borophene for H2O2 and tetracycline detection
    Ahmed SR, Sherazee M, Das P, Shalauddin M, Akhter S, Basirun WJ, et al.
    Biosens Bioelectron, 2024 Feb 15;246:115857.
    PMID: 38029708 DOI: 10.1016/j.bios.2023.115857
    This study unveils the electrochemically-enhanced nanozymatic activity exhibited by borophene during the reaction of 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2. Herein, the surface of the pristine borophene was first modified with the addition of thiocyanate groups to improve hydroxyl radical (•OH) scavenging activity. Then, the oxidation reaction of TMB was accelerated under applied electrochemical potential. Both factors significantly improved the detection limit and drastically decreased the detection time. DPPH testing revealed that the radical scavenging nature of borophene was more than 70%, boosting its catalytic activity. In the presence of H2O2, borophene catalyzed the oxidation of TMB and produced a blue-colored solution that was linearly correlated with the concentration of H2O2 and allowed for the detection of H2O2 up to 38 nM. The present finding was further extended to nanozymatic detection of tetracyclines (TCs) using a target-specific aptamer, and the results were colorimetrically quantifiable up to 1 μM with a LOD value of 150 nM. Moreover, transferring the principles of the discussed detection method to form a portable and disposable paper-based system enabled the quantification of TCs up to 0.2 μM. All the sensing experiments in this study indicate that the nanozymatic activity of borophene has significantly improved under electrochemical potential compared to conventional nanozyme-based colorimetric detection. Hence, the present discovery of electrochemically-enhanced nanozymatic activity would be promising for various sensitive and time-dependent colorimetric sensor development initiatives in the future.
  11. Electrochemical investigation on the corrosion inhibition of mild steel by Quinazoline Schiff base compounds in hydrochloric acid solution
    Khan G, Basirun WJ, Kazi SN, Ahmed P, Magaji L, Ahmed SM, et al.
    J Colloid Interface Sci, 2017 Sep 15;502:134-145.
    PMID: 28478220 DOI: 10.1016/j.jcis.2017.04.061
    The inhibitory effect of two Schiff bases 3-(5-methoxy-2-hydroxybenzylideneamino)-2-(-5-methoxy-2-hydroxyphenyl)-2,3-dihydroquinazoline-4(1H)-one (MMDQ), and 3-(5-nitro-2-hydroxybenzylideneamino)-2(5-nitro-2-hydroxyphenyl)-2,3-dihydroquinazoline-4(1H)-one (NNDQ) on the corrosion of mild steel in 1M hydrochloric acid were studied using mass loss, potentiodynamic polarization technique and electrochemical impedance spectroscopy measurements at ambient temperature. The investigation results indicate that the Schiff Bases compounds with an average efficiency of 92% at 1.0mM of additive concentration have fairly effective inhibiting properties for mild steel in hydrochloric acid, and acts as mixed type inhibitor character. The inhibition efficiencies measured by all measurements show that the inhibition efficiencies increase with increase in inhibitor concentration. This reveals that the inhibitive mechanism of inhibitors were primarily due to adsorption on mild steel surface, and follow Langmuir adsorption isotherm. The temperature effect on the inhibition process in 1MHCl with the addition of investigated Schiff bases was studied at a temperature range of 30-60°C, and the activation parameters (Ea, ΔH and ΔS) were calculated to elaborate the corrosion mechanism. The differences in efficiency for two investigated inhibitors are associated with their chemical structures.
  12. Fulltext Electrodeposition of quaternary alloys in the presence of magnetic field
    Ebadi M, Basirun WJ, Alias Y, Mahmoudian M
    Chem Cent J, 2010;4:14.
    PMID: 20604934 DOI: 10.1186/1752-153X-4-14
    Electrodeposition of Ni-Co-Fe-Zn alloys was done in a chloride ion solution with the presence and absence of a Permanent Parallel Magnetic Field (PPMF). The PPMF was applied parallel to the cathode surface. The deposition profile was monitored chronoamperometrically. It was found that the electrodeposition current was enhanced in the presence of PPMF (9 T) compared to without PPMF. The percentage of current enhancement (Gamma%) was increased in the presence of PPMF, with results of Gamma% = 11.9%, 16.7% and 18.5% at -1.1, -1.2 and -1.3 V respectively for a 2400 sec duration. In chronoamperometry, the Composition Reference Line (CRL) for Ni was around 57%, although the nobler metals (i.e. Ni, Co) showed anomalous behaviour in the presence of Zn and Fe. The anomalous behaviour of the Ni-Co-Fe-Zn electrodeposition was shown by the Energy Dispersive X-Ray (EDX) results. From Atomic Force Microscopy (AFM) measurements, it was found that the surface roughness of the Ni-Co-Fe-Zn alloy films decreased in the presence of a PPMF.
  13. Enhanced amperometric detection of paracetamol by immobilized cobalt ion on functionalized MWCNTs - Chitosan thin film
    Akhter S, Basirun WJ, Alias Y, Johan MR, Bagheri S, Shalauddin M, et al.
    Anal Biochem, 2018 06 15;551:29-36.
    PMID: 29753720 DOI: 10.1016/j.ab.2018.05.004
    In the present study, a nanocomposite of f-MWCNTs-chitosan-Co was prepared by the immobilization of Co(II) on f-MWCNTs-chitosan by a self-assembly method and used for the quantitative determination of paracetamol (PR). The composite was characterized by field emission scanning electron microscopy (FESEM) and energy dispersive x-ray analysis (EDX). The electroactivity of cobalt immobilized on f-MWCNTs-chitosan was assessed during the electro-oxidation of paracetamol. The prepared GCE modified f-MWCNTs/CTS-Co showed strong electrocatalytic activity towards the oxidation of PR. The electrochemical performances were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under favorable experimental conditions, differential pulse voltammetry showed a linear dynamic range between 0.1 and 400 μmol L-1 with a detection limit of 0.01 μmol L-1 for the PR solution. The fabricated sensor exhibited significant selectivity towards PR detection. The fabricated sensor was successfully applied for the determination of PR in commercial tablets and human serum sample.
  14. Fabrication and Characterization of SnO-Cu₂O Mixed Metal Oxide Thin Films for Photoelectrochemical Applications
    Ahmed S, Shahid MM, Bakar SA, Arshed N, Basirun WJ, Fouad H
    J Nanosci Nanotechnol, 2020 12 01;20(12):7705-7709.
    PMID: 32711646 DOI: 10.1166/jnn.2020.18570
    Herein, we report the synthesis of SnO, Cu₂O and SnO-Cu₂O mixed oxide thin films on fluorinedoped tin oxide (FTO) substrate by Aerosol-Assisted Chemical Vapour Deposition (AACVD) process using [Cu (dmae)₂(H₂O)] and [Sn (dmae) (OAc)]₂ as molecular precursors for SnO and Cu₂O, respectively at 400 °C. The X-ray diffraction (XRD) pattern can be ascribed to the tetragonal phase of SnO crystals with space group P4 and cubic phase of Cu₂O crystals with space group Pn- 3m/nmm, respectively. The surface morphology characteristics of SnO, Cu₂O and SnO-Cu₂Omixed oxide have been investigated using Field Emission Scanning Electron Microscope (FESEM) which revealed that the SnO was grown homogeneously in cubical shape while Cu₂O possess nano balls shaped morphologies. The UV band gap values of SnO-Cu₂O mixed oxide thin film was found to be 2.6 eV appropriate for photoelectrochemical (PEC) applications. The synthesized material was proposed for PEC applications and has shown enhanced catalytic performance in the presence of light.
  15. Fabrication and deformation behaviour of multilayer Al2O3/Ti/TiO2 nanotube arrays
    Baradaran S, Basirun WJ, Zalnezhad E, Hamdi M, Sarhan AA, Alias Y
    J Mech Behav Biomed Mater, 2013 Apr;20:272-82.
    PMID: 23453827 DOI: 10.1016/j.jmbbm.2013.01.020
    In this study, titanium thin films were deposited on alumina substrates by radio frequency (RF) magnetron sputtering. The mechanical properties of the Ti coatings were evaluated in terms of adhesion strength at various RF powers, temperatures, and substrate bias voltages. The coating conditions of 400W of RF power, 250°C, and a 75V substrate bias voltage produced the strongest coating adhesion, as obtained by the Taguchi optimisation method. TiO2 nanotube arrays were grown as a second layer on the Ti substrates using electrochemical anodisation at a constant potential of 20V and anodisation times of 15min, 45min, and 75min in a NH4F electrolyte solution (75 ethylene glycol: 25 water). The anodised titanium was annealed at 450°C and 650°C in a N2 gas furnace to obtain different phases of titania, anatase and rutile, respectively. The mechanical properties of the anodised layer were investigated by nanoindentation. The results indicate that Young's modulus and hardness increased with annealing temperature to 650°C.
  16. Facile and greener hydrothermal honey-based synthesis of Fe3 O 4 /Au core/shell nanoparticles for drug delivery applications
    Rasouli E, Basirun WJ, Johan MR, Rezayi M, Darroudi M, Shameli K, et al.
    J Cell Biochem, 2019 04;120(4):6624-6631.
    PMID: 30368873 DOI: 10.1002/jcb.27958
    In the present research, we report a greener, faster, and low-cost synthesis of gold-coated iron oxide nanoparticles (Fe3 O4 /Au-NPs) by different ratios (1:1, 2:1, and 3:1 molar ratio) of iron oxide and gold with natural honey (0.5% w/v) under hydrothermal conditions for 20 minutes. Honey was used as the reducing and stabilizing agent, respectively. The nanoparticles were characterized by X-ray diffraction (XRD), UV-visible spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), vibrating sample magnetometer (VSM), and fourier transformed infrared spectroscopy (FT-IR). The XRD analysis indicated the presence of Fe3 O4 /Au-NPs, while the TEM images showed the formation of Fe3 O4 /Au-NPs with diameter range between 3.49 nm and 4.11 nm. The VSM study demonstrated that the magnetic properties were decreased in the Fe3 O4 /Au-NPs compared with the Fe3 O4 -NPs. The cytotoxicity threshold of Fe3 O4 /Au-NPs in the WEHI164 cells was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It was demonstrated no significant toxicity in higher concentration up to 140.0 ppm which can become the main candidates for biological and biomedical applications, such as drug delivery.
  17. Graphene oxide and gold nanoparticle based dual platform with short DNA probe for the PCR free DNA biosensing using surface-enhanced Raman scattering
    Khalil I, Yehye WA, Julkapli NM, Rahmati S, Sina AA, Basirun WJ, et al.
    Biosens Bioelectron, 2019 Apr 15;131:214-223.
    PMID: 30844598 DOI: 10.1016/j.bios.2019.02.028
    Surface-enhanced Raman scattering (SERS) based DNA biosensors have considered as excellent, fast and ultrasensitive sensing technique which relies on the fingerprinting ability to produce molecule specific distinct spectra. Unlike conventional fluorescence based strategies SERS provides narrow spectral bandwidths, fluorescence quenching and multiplexing ability, and fitting attribute with short length probe DNA sequences. Herein, we report a novel and PCR free SERS based DNA detection strategy involving dual platforms and short DNA probes for the detection of endangered species, Malayan box turtle (MBT) (Cuora amboinensis). In this biosensing feature, the detection is based on the covalent linking of the two platforms involving graphene oxide-gold nanoparticles (GO-AuNPs) functionalized with capture probe 1 and gold nanoparticles (AuNPs) modified with capture probe 2 and Raman dye (Cy3) via hybridization with the corresponding target sequences. Coupling of the two platforms generates locally enhanced electromagnetic field 'hot spot', formed at the junctions and interstitial crevices of the nanostructures and consequently provide significant amplification of the SERS signal. Therefore, employing the two SERS active substrates and short-length probe DNA sequences, we have managed to improve the sensitivity of the biosensors to achieve a lowest limit of detection (LOD) as low as 10 fM. Furthermore, the fabricated biosensor exhibited sensitivity even for single nucleotide base-mismatch in the target DNA as well as showed excellent performance to discriminate closely related six non-target DNA sequences. Although the developed SERS biosensor would be an attractive platform for the authentication of MBT from diverse samples including forensic and/or archaeological specimens, it could have universal application for detecting gene specific biomarkers for many diseases including cancer.
  18. Fulltext Graphene oxide electrocatalyst on MnO₂ air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution
    Basirun WJ, Sookhakian M, Baradaran S, Endut Z, Mahmoudian MR, Ebadi M, et al.
    Sci Rep, 2015;5:9108.
    PMID: 25765731 DOI: 10.1038/srep09108
    Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6 M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13 mW cm(-2), in contrast to MnO2, which produced a maximum power density of 9.2 mW cm(-2). The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms.
  19. Fulltext Graphene-Gold Nanoparticles Hybrid-Synthesis, Functionalization, and Application in a Electrochemical and Surface-Enhanced Raman Scattering Biosensor
    Khalil I, Julkapli NM, Yehye WA, Basirun WJ, Bhargava SK
    Materials (Basel), 2016 May 24;9(6).
    PMID: 28773528 DOI: 10.3390/ma9060406
    Graphene is a single-atom-thick two-dimensional carbon nanosheet with outstanding chemical, electrical, material, optical, and physical properties due to its large surface area, high electron mobility, thermal conductivity, and stability. These extraordinary features of graphene make it a key component for different applications in the biosensing and imaging arena. However, the use of graphene alone is correlated with certain limitations, such as irreversible self-agglomerations, less colloidal stability, poor reliability/repeatability, and non-specificity. The addition of gold nanostructures (AuNS) with graphene produces the graphene-AuNS hybrid nanocomposite which minimizes the limitations as well as providing additional synergistic properties, that is, higher effective surface area, catalytic activity, electrical conductivity, water solubility, and biocompatibility. This review focuses on the fundamental features of graphene, the multidimensional synthesis, and multipurpose applications of graphene-Au nanocomposites. The paper highlights the graphene-gold nanoparticle (AuNP) as the platform substrate for the fabrication of electrochemical and surface-enhanced Raman scattering (SERS)-based biosensors in diverse applications as well as SERS-directed bio-imaging, which is considered as an emerging sector for monitoring stem cell differentiation, and detection and treatment of cancer.
  20. Fulltext In-situ study of electrochemical migration of tin in the presence of bromide ion
    Lee EL, Haseeb ASMA, Basirun WJ, Wong YH, Sabri MFM, Low BY
    Sci Rep, 2021 Aug 03;11(1):15768.
    PMID: 34344974 DOI: 10.1038/s41598-021-95276-0
    The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br-) in the range of 10-6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br- concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br- concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br- are also suggested.
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