[show abstract][hide abstract] ABSTRACT: The application of Silicon nanowire (SiNW) as sensing nanomaterial for detection of biological and chemical species has gained attention due to its unique properties. In this review, a short description is also demonstrated on the synthesis techniques of SiNWs and recent progress on sensor development based on electrochemical methods, fluorescence field-effect transistors (FET) and Surface-enhanced Raman scattering (SERS) spectroscopy. We also discussed on the challenges of SiNWs based sensors
in the future.
Journal of Nanomaterials 11/2013; · 1.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: Poly(ethyl hydrazide)-grafted oil palm empty fruit bunch fibre (peh-g-opefb) was successfully prepared by heating poly(methyl acrylate)-grafted opefb (pma-g-opefb) at 60 °C for 4 h with a solution of hydrazine hydrate (15% v/v) in ethanol. The Fourier transform infrared spectrum of the product shows a secondary amine peak at 3267 cm-1, with amide carbonyl peaks at 1729 cm-1 and 1643 cm-1. The chelating ability of peh-g-opefb was tested with copper ion in aqueous solution. A batch adsorption study revealed that maximum adsorption of copper ion was achieved at pH 5. An isotherm study showed the adsorption follows a Langmuir model, with a maximum adsorption capacity of 43.48 mg g-1 at 25 °C. A kinetic study showed that the adsorption of copper ion rapidly reaches equilibrium and follows a pseudo-second-order kinetic model, with a constant rate of 7.02 × 10-4 g mg-1 min-1 at 25 °C. The Gibbs free energy, ∆G⁰, value is negative, indicating a spontaneous sorption process. Entropy, ∆S⁰, gives a positive value, indicating that the system is becoming increasingly disordered after the adsorption of copper ion. A positive enthalpy value, ∆H⁰, shows that the endothermic process takes place during the adsorption and is more favourable at high temperatures.
[show abstract][hide abstract] ABSTRACT: Molecularly imprinted polymers (MIPs) were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA) and polystyrene (PS) after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP) and the PS membrane with MIP (PS-MIP) was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo-second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol.
International Journal of Molecular Sciences 01/2013; 14(2):3993-4004. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: The oil palm, an economically important tree, has been one of the world's major sources of edible oil and a significant precursor of biodiesel fuel. Unfortunately, it now faces the threat of a devastating disease. Many researchers have identified Ganoderma boninense as the major pathogen that affects the oil palm tree and eventually kills it. But identification of the pathogen is just the first step. No single method has yet been able to halt the continuing spread of the disease. This paper discusses the modes of infection and transmission of Ganoderma boninense and suggests techniques for its early detection. Additionally, the paper proposes some possible ways of controlling the disease. Such measures, if implemented, could contribute significantly to the sustainability of the palm oil industry in South East Asia.
[show abstract][hide abstract] ABSTRACT: Purpose – The purpose of this paper is to describe a capacitive biosensor device consisting of an enzyme electrode and a simple detector which has been developed for histamine measurement. Design/methodology/approach – In this analysis, degradation of histamine through enzymatic reaction produces signal that is monitored using a simple detector equipped with “astable” multivibrator operation circuit (in capacitor-resistor circuit). Findings – Different frequency (f) readings have been obtained for glucose, alcohol and histamine in different concentration levels, showing the ability of this simple device system to measure their dielectric constant (k) as formulated by the equation f=(1.44d)/ [kA (R1+2R2)]. The analysis using smaller electrode gap (d) produces higher value of f, indicating that d, is directly proportional to f. For histamine, by using immobilized enzyme electrode, the results show that the change of dielectric properties during the 300-second reaction period could also be monitored. A linear relationship is obtained between concentration and frequency from 50 to 200?ppm. Practical implications – Based on this result, an enzyme electrode and “astable” operation circuits have the potential to be used in the development of a simple capacitive biosensor device. Originality/value – The paper is an outcome of experimental work carried out to observe capacitive sensing behavior using an immobilized enzyme, to measure biological samples, especially histamine.
[show abstract][hide abstract] ABSTRACT: The effective removal of o-cresol is currently both an environmental and economic challenge. ZnO is not only an efficient photocatalyst but is also cost effective, as its photoabsorption can extend from the ultraviolet (UV) to the visible range thereby allowing the use of inexpensive visible light sources, such as sunlight. The principal objective of the present work is to investigate the visible light-driven removal of o-cresol from aqueous solution in the presence of 1.0 wt% Mn-doped ZnO. To measure the efficiency ofphotodegradation, the variables studied included the amount ofphotocatalyst, concentration of o-cresol, pH and irradiation time. The concentration ofo-cresol and residual organic carbon was monitored using a UV-visible spectrophotometer, ultra high-pressure liquid chromatography and a total organic carbon analyser. The optimum conditions under which the photodegradation of o-cresol was most favourable corresponded to 1.5 g/l ZnO, 35 ppm o-cresol and pH 9. The ZnO-1 wt% Mn photoprocess has demonstrated reusability for more than three times, which warrants its scale-up from laboratory- to in industrial-scale application.
[show abstract][hide abstract] ABSTRACT: This work reports the synthesis and characterization of a hybrid molecularly imprinted polymer (MIP) membrane for removal of methylene blue (MB) in an aqueous environment. MB-MIP powders were hybridized into a polymer membrane (cellulose acetate (CA) and polysulfone (PSf)) after it was ground and sieved (using 90 µm sieve). MB-MIP membranes were prepared using a phase inversion process. The MB-MIP membranes were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Parameters investigated for the removal of MB by using membrane MB-MIP include pH, effect of time, concentration of MB, and selectivity studies. Maximum sorption of MB by PSf-MB-MIP membranes and CA-MB-MIP membranes occurred at pH 10 and pH 12, respectively. The kinetic study showed that the sorption of MB by MB-MIP membranes (PSf-MB-MIP and CA-MB-MIP) followed a pseudo-second-order-model and the MB sorption isotherm can be described by a Freundlich isotherm model.
[show abstract][hide abstract] ABSTRACT: Electrochemical DNA biosensor was successfully
developed by depositing the ionic liquid (e.g., 1-ethyl-3-
methylimidazolium trifluoromethanesulfonate ([EMIM]
[Otf])), ZnO nanoparticles, and chitosan (CHIT) nanocomposite
membrane on a modified gold electrode (AuE). The
electrochemical properties of the [EMIM][Otf]/ZnO/CHIT/
AuE for detection of DNA hybridization were studied. Under
optimal conditions using cyclic voltammetry, the target DNA
sequences could be detected in the concentration range of
1.0×10−18 to 1.82×10−4 mol L−1, and with the detection limit of 1.0×10−19 mol L−1. This DNA biosensor detection
approaches provide a quick, sensitive, and convenient method
to be used in the identification of Trichoderma harzianum
Journal of Solid State Electrochemistry 01/2012; 16(1-2.234):273-282. · 2.28 Impact Factor
[show abstract][hide abstract] ABSTRACT: Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6-9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.
International Journal of Molecular Sciences 01/2012; 13(1):302-15. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: The effect of composition on nickel cobaltites prepared by co-precipitation was investigated. Various compositions were
synthesised under different heat treatment conditions. The formation mechanism, lattice parameter and crystallite size were
determined by various techniques. X-ray dffraction (XRD) analysis revealed that the optimum condition for the formation
of single phase nickel-cobalt oxide (NiCo2O4) can be obtained from solution containing Ni: Co ratio of 33.3 mol%: 66.7
mol% with heat treatment at 400°C. The presence of pure phase NiCo2O4 with the particle size of approximately 34.10
nm was also observed in field emission scanning electron microscopy (FESEM). The crystallinity of the synthesized oxides
was improved with the increment of Ni content.
[show abstract][hide abstract] ABSTRACT: Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450 degrees C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90-130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the,predictive and the experimental results.
Journal of Environmental Sciences 01/2012; 24(9):1694-701. · 1.77 Impact Factor
[show abstract][hide abstract] ABSTRACT: Liquid-liquid iron(III) extraction was investigated using benzyl fatty hydroxamic acids (BFHAs) and methyl fatty hydroxamic acids (MFHAs) as chelating agents through the formation of iron(III) methyl fatty hydroxamate (Fe-MFHs) or iron(III) benzyl fatty hydroxamate (Fe-BFHs) in the organic phase. The results obtained under optimized conditions, showed that the chelating agents in hexane extract iron(III) at pH 1.9 were realized effectively with a high percentage of extraction (97.2% and 98.1% for MFHAs and BFHAs, respectively). The presence of a large amount of Mg(II), Ni(II), Al(III), Mn(II) and Co(II) ions did affect the iron(III) extraction. Finally stripping studies for recovering iron(III) from organic phase (Fe-MFHs or Fe-BFHs dissolved in hexane) were carried out at various concentrations of HCl, HNO(3) and H(2)SO(4). The results showed that the desired acid for recovery of iron(III) was 5 M HCl and quantitative recovery of iron(III) was achieved from Fe(III)-MFHs and Fe(III)-BFHs solutions in hexane containing 5 mg/L of Fe(III).
International Journal of Molecular Sciences 01/2012; 13(2):2148-59. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: Fatty hydroxamic acids derivatives based on palm kernel oil which are phenyl fatty hydroxamic acids (PFHAs), methyl fatty hydroxamic acids (MFHAs), isopropyl fatty hydroxamic acids (IPFHAs) and benzyl fatty hydroxamic acids (BFHAs) were applied as chelating agent for copper liquid-liquid extraction. The extraction of copper from aqueous solution by MFHAs, PFHAs, BFHAs or IPFHAs were carried out in hexane as an organic phase through the formation of copper methyl fatty hydroxamate (Cu-MFHs), copper phenyl fatty hydroxamate (Cu-PFHs), copper benzyl fatty hydroxamate (Cu-BFHs) and copper isopropyl fatty hydroxamate (Cu-IPFHs). The results showed that the fatty hydroxamic acid derivatives could extract copper at pH 6.2 effectively with high percentage of extraction (the percentages of copper extraction by MFHAs, PFHAs, IPFHs and BFHAs were found to be 99.3, 87.5, 82.3 and 90.2%, respectively). The extracted copper could be quantitatively stripped back into sulphuric acid (3M) aqueous solution. The obtained results showed that the copper recovery percentages from Cu-MFHs, Cu-PFHs, Cu-BFHs and Cu-IPFHs are 99.1, 99.4, 99.6 and 99.9 respectively. The copper extraction was not affected by the presence of a large amount of Mg (II), Ni (II), Al (III), Mn (II) and Co (II) ions in the aqueous solution.
Journal of oleo science 01/2012; 61(4):189-95. · 1.24 Impact Factor
[show abstract][hide abstract] ABSTRACT: Electrochemical DNA biosensor was fabricated using the ZnO nanoparticles/chitosan (CHIT) nanocomposite
membrane on modified gold electrode (AuE) as the working electrode. The ZnO/CHIT was used as a modified-AuE for
the immobilization of the single-stranded DNA probe. This particular DNA biosensor provided some advantages such as
the biocompatibility of the ZnO nanoparticles, good film forming ability of CHIT, and the high conductivity of AuE.
Methylene blue was used as the electrochemical indicator for monitoring the hybridization reaction following the
hybridization of the target DNA sequence. Differential pulse voltammetry was used for recording the electrochemical
response of MB. The specific target DNA sequence could be detected in the concentration range of 1.0 x 10-14 to 1.82 x
10-4 mol L-1, with the detection limit at 1.0 x 10-15 mol L-1. This novel approach of constructing an electrochemical
biosensor allowed the hybridization of synthetic target DNA. In addition, it also facilitated hybridization with template—
DNA taken from real samples. The results proved that the ZnO/CHIT/AuE electrode has the potential for the sensitive
detection of specific sequence related to a Trichoderma harzianum gene.
Current Analytical Chemistry 07/2011; 7(2.134):296- 305. · 1.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: A conductance study of the interaction between titanium (III) cation and tris(2-pyridyl) methylamine (tpm), in water-acetonitrile mixtures was carried out at various temperatures. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data. The stability constants of 1:1 (M:L) complexes of tpm with titanium (III) cation, the Gibbs standard free energies ( c G ), the standard enthalpy changes ( c H ) and the standard entropy changes ( c S ) for the formation of these complexes in acetonitrile–water (AN–H 2 O) binary mixtures have been determined conductometrically. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program, GENPLOT.
Int. J. Electrochem. Sci. International Journal. 01/2011; 6:4378-4387.
[show abstract][hide abstract] ABSTRACT: Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment.
[show abstract][hide abstract] ABSTRACT: Boric acid was examined for antifungal activity against several species of fungi. The growth and production of β-glucosidase in several strains of fungi were tested in the media containing various concentrations of boric acid. The results indicated that the growth of Trichoderma strains was reduced with increasing amount of boric acid up to 0.3% (w/v). However, Paecilomyces variotii was able to tolerate boric acid above 0.3% (w/v) by increasing its growth. Trichoderma also showed low production of β-glucosidase as compared to P. variotii. Present study revealed that boric acid works as effective fungicide by inhibiting the production of β-glucosidase and the growth of fungi. This suggests that boric acid might be useful for the treatment of fungal infection caused by P. variotii or Trichoderma strains.
African journal of microbiology research 01/2011; 5:2451-2454. · 0.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: Abstract An electrochemical DNA biosensor was developed
that is based on a gold electrode modified with a nanocomposite
membrane made from an ionic liquid, ZnO
nanoparticles and chitosan. A single-stranded DNA probe
was immobilized on this electrode. Acridine orange was used
as the hybridization probe for monitoring the hybridization of
the target DNA. The biosensor was capable of detecting target
DNA in the concentration range from 1.0×10–14 to 1.8×10–
4 mol L-1, with a detection limit of 1.0×10–15 mol L-1. The
approach towards constructing a DNA biosensor allows
studies on the hybridization even with crude DNA fragments
and also to analyze sample obtained from real samples. The
results show that the DNA biosensor has the potential for
sensitive detection of a specific sequence of the Trichoderma
harzianum gene and provides a quick, sensitive and
convenient method for the study of microorganisms.