Edward Ogabiela - Academia.edu (original) (raw)

Papers by Edward Ogabiela

The determination of phosphate is of environmental and clinical importance because it is one of t... more The determination of phosphate is of environmental and clinical importance because it is one of the factors associated with eutrophication, which disrupts aquatic life cycles. However, phosphate is also an essential component of all living organisms. Various analytical methods, such as chromatography, colorimetry, optical fluorescent spectroscopy and electrochemical methods have been used for the determination of phosphate. However, these methods require skilled operators, expensive instrumentation, and, in some cases, involve usage of potentially carcinogenic chemicals. In recent years, the use of biosensors has attracted a lot of interest as a simple and rapid alternative to the traditional methods because of their enormous advantages, such as high selectivity, simplicity of use and the possibility for miniaturization. In this thesis, various configurations of phosphate nanobiosensors are reported. The thesis is structured into eight chapters, with Chapter 1 comprising of the gene...

Total hydrocarbon and physicochemical parameters of water quality were investigated in the Calaba... more Total hydrocarbon and physicochemical parameters of water quality were investigated in the Calabar river estuary from January to June. Total hydrocarbon (THC) in surface water was observed to be below detectable limit (0.00mg/l) throughout the study. THC in sediment varied between 15.8mg/g and 130mg/g with a highest mean value of 127.9±3.2mg/g during dry season and between 9.8mg/g and 122.2mg/g with 45.3±66.6 as the highest mean during wet season, indicating a significant increase during the dry season (ANOVA, P < 0.05). THC values also increased significantly downstream from a mean concentration of 26.4 ±92mg/g in station 1 to 127.9± 2.3mg/g in station 4 in the dry season (P<0.05). Dissolved Oxygen (DO) ranged from 1.0mg/l to 7.1mg/l. DO showed significant (P<0.05) spatial variation during dry season. pH ranged between 5.94 and 7.34. Dry season values were significantly higher than wet season measurements (P<0.05). There were significant (P<0.05) spatial variations i...

Trace metal determination in human blood have become important to obtain information regarding th... more Trace metal determination in human blood have become important to obtain information regarding the health status of individuals since blood is a good indicator of current body burden of metals. In this study the levels of Nickel, Manganese, Cobalt and Chromium were determined in whole blood of people of different age groups ranging from 1-40 years residing in Derata, Anka, Nigeria. Thirty-three blood samples were collected from the subjects and analyzed using Atomic Absorption Spectrophotometer after wet digestion. The trace metal levels in mg/l were 0.166±141, 0.935±0.491, 0.318±141 and 1.321±0.376 for Cr, Ni, Mn and Co respectively. The result obtained indicated no significant difference in metal levels between the age groups except for cobalt. Apart from Manganese, the concentrations were found to be above the maximum allowable limits for these metals in human blood. The health implications of these research findings were also discussed.

Zamfara State, Nigeria has a lot of untapped mineral resources. The natives tap these minerals cr... more Zamfara State, Nigeria has a lot of untapped mineral resources. The natives tap these minerals crudely with so many mining sites scattered all over the state. Dareta village is one of such mining fields. Recently, many deaths are being recorded in Anka, Bukkuyum and Maru LGAs of the state. These deaths are attributed to lead poisoning which necessitated immediate remediation by the Nigerian authorities with technical assistance from a coalition of international organizations. Levels of lead, cadmium and copper in soil were investigated in Dareta village, Anka LGA, after the remediation exercise. Lead ranged between 81.65 and 684.27 mg/kg dry weight, Cadmium between 0.02 and 1.88 mg/kg dry weight and Copper between 4.42 and 146.49 mg/kg dry weight. Although the contamination situation was less severe compared to the levels before the remediation exercise, findings from this study shows that Lead, Cadmium and Copper levels in soil are worrying. The need for further attention is obviou...

Many tanneries are located at Sharada Industrial Estate in Kano. these tanneries discharge their ... more Many tanneries are located at Sharada Industrial Estate in Kano. these tanneries discharge their effluents into canals that eventually flow into the Challawa River. Tannery effluents were collected from the effluent confluence point at Sharada Industrial Estate and some physiochemical parameters of the waste water such as total solids, total suspended solids and total dissolved solids, conductivity, alkalinity, chloride, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), sulphide and chromium were determined using the Standard Methods. The concentrations of these parameters were higher than the limits set by the Federal Ministry of Environment (FEMEnv) for discharge of effluents by the Tannery Sector. The tannery effluents from Sharada Industrial Estate pollute the Challawa River in Kano.

The evaluation of metals levels in cow blood is important for assessing the potential effects of ... more The evaluation of metals levels in cow blood is important for assessing the potential effects of pollutants on grazing cattle and for quantifying contaminant intakes by humans. Hence Atomic Absorption Spectrophotometer (AAS) was used to determine trace and heavy metals of toxicological implications in cow blood. Six trace metals (Fe, Zn, Cu, Mn, Ni, Al) were found in a range between 0.18±0.10 to 36.62±7.71ppm and 0.20±0.06 to 35.11±14.78ppm in sample area A and B respectively. Three heavy metals (Cd, Pb, Cr) of toxicological implications were also found to range between 0.12±0.04 to 2.12±1.54 in area A and 0.17±0.14 to 2.81±0.90ppm in study area B. No statistically significant difference was observed between the two study areas for all the elements determined at 95%confidence levels. Except for Cu and Mn the values obtained were higher than the allowable limit for trace elements in blood.

Milk is a very important component of human diet. The presence of toxic element in milk may creat... more Milk is a very important component of human diet. The presence of toxic element in milk may create significant health problems. In this study, metal levels of fresh cow milk were determined. Fresh milk samples were collected from 17 cows grazed around challawa industrial estate, Kano and 9 cows grazed on open fields in Zaria, Kaduna state. Metal levels were determined using Atomic Absorption Spectrophotometer after wet digestion. The result shows the mean concentration of Al, Mn, Ni, Cu, Cd, Pb, Cr, Fe, and Zn in samples from Kano to be 10. respectively. The concentrations were very high as the metal levels of both Kano and Zaria samples exceeded the WHO permissible limits. Except for Pb, Zn and Mn, metal levels of cow milk from Kano were higher than those obtained from Zaria, though the result indicated no statistically significant difference between them. The implication of the results obtained to public health was discussed.

Microchimica Acta, 2015

ABSTRACT The article describes a method for rapid and visual determination of Hg(II) ion using un... more ABSTRACT The article describes a method for rapid and visual determination of Hg(II) ion using unmodified gold nanoparticles (Au-NPs). It involves the addition of Au-NPs to a solution containing Hg(II) ions which, however, does not induce a color change. Next, a solution of lysine is added which induces the aggregation of the Au-NPs and causes the color of the solution to change from wine-red to purple. The whole on-site detection process can be executed in less than 15 min. Other amines (ethylenediamine, arginine, and melamine) were also investigated with respect to their capability to induce aggregation. Notably, only amines containing more than one amino group were found to be effective, but a 0.4 μM and pH 8 solution of lysine was found to give the best results. The detection limits for Hg (II) are 8.4 pM (for instrumental read-out) and 10 pM (for visual read-out). To the best of our knowledge, this LOD is better than those reported for any other existing rapid screening methods. The assay is not interfered by the presence of other common metal ions even if present in 1000-fold excess over Hg(II) concentration. It was successfully applied to the determination of Hg(II) in spiked tap water samples. We perceive that this method provides an excellent tool for rapid and ultrasensitive on-site determination of Hg(II) ions at low cost, with relative ease and minimal operation.

Biosensors & bioelectronics, Jan 14, 2015

A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidas... more A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidase (PyOx) and its cofactors, thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), with a highly ordered gold nanowires array (AuNWA) has been developed. The successful integration of PyOx and the co-factors, via crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLA), onto the AuNWA was confirmed by cyclic voltammetry and amperometry. The resulting nanobiosensor achieved a detection limit of 0.1µM, a linear concentration range of 12.5-1000µM, and a sensitivity of 140.3µAmM(-1)cm(-2). Notably, the incorporation of the AuNWA reduced the required PyOx concentration by 70-120 fold and the presence of common interferants, such as chloride, sulfate, fluoride, nitrite and nitrate ions did not interfere with phosphate detection. Furthermore, the nanobiosensor demonstrated a very high stability with repeated use over two weeks and was successfully used for the determin...

Journal of The Electrochemical Society, 2014

ABSTRACT Well aligned Pt/Au alloy nanowire arrays are successfully synthesized and used as the su... more ABSTRACT Well aligned Pt/Au alloy nanowire arrays are successfully synthesized and used as the substrate for the construction of phosphate biosensors. Pyruvate oxidase is immobilized onto the nanowire surface together with co-factors via cross linking approach. Morphology, composition, structure and chemical state of the nanowires are characterized by SEM, TEM, EDS and XPS, and the electrochemical behaviors of the as-prepared phosphate biosensors are investigated by cyclic voltammogramic and chronoamperometric techniques. Especially, the influence of the composition and aspect ratio of Pt/Au alloy nanowire arrays on the response of phosphate biosensors are studied as well. The present phosphate biosensor shows a high sensitivity of 50.5 μA· cm−2 ·mM−1 and a wide linear range between 248 and 1456 μM toward the detection of phosphate. In addition, the biosensor also exhibits good selectivity and stability, which promises great potential in phosphate detection applications.

Journal of the Electrochemical Society, 2014

ABSTRACT B291 0013-4651/2014/161(14)/B291/6/$31.00 © The Electrochemical Society A hybrid flow in... more ABSTRACT B291 0013-4651/2014/161(14)/B291/6/$31.00 © The Electrochemical Society A hybrid flow injection-nanobiosensor system for the detection of glucose at low potential is presented in this paper. For the fabrication of the biosensor, highly ordered gold nanowire arrays (AuNWAs) are synthesized by direct electrodeposition in combination with tem-plate approach. Glucose oxidase and horseradish peroxidase are immobilized on the surface of the resultant AuNWAs by cross-linking with glutaraldehyde (GLA) and bovine serum albumin (BSA). In combination with a flow injection system, the biosensor demon-strate high performance in glucose detection with a sensitivity of 25.34 μA · cm −2 · mM −1 , a linear range between 5 and 1000 μM, a detection limit of 1 μM, and a sample throughput of 45 h −1 . High selectivity against uric acid, nitrate and chloride ions is also achieved. In addition, it shows good reproducibility, repeatability and stability, which are beneficial for the practical applications in glucose detection. Finally, the developed nanobiosensor is applied to the detection of glucose in river water and the biosensor presents good performance with a relative standard deviation of 1.33% and a recovery rate of 100.4∼102.9%. © 2014 The Electrochemical Society. [DOI: 10.1149/2.0061414jes] All rights reserved.

Journal of Plant Studies, 2012

The composition of fatty acids (FA) and vitamin E in seed oils of Albezia lebbeck (AL), Citrus si... more The composition of fatty acids (FA) and vitamin E in seed oils of Albezia lebbeck (AL), Citrus sinensis (CS), Terminalia catapa (TC), Tamarindus indica (TI) and Citrullus vulgaris (CV) was investigated. The oil yields were obtained by solvent extraction and analysed for fatty acids by Gas Chromatography Mass Spectroscopy (GC-MS). The oil yields of the seeds were found to be 8.

Global Journal of Pure and Applied Sciences, 2006

Global Journal of Pure and Applied Sciences, 2009

The heavy metal composition of some commercial fertilizers and soil supplements used in Zaria wer... more The heavy metal composition of some commercial fertilizers and soil supplements used in Zaria were analysed. The fertilizers analysed include Liquid Organic fertilizer, Palette Organic fertilizer, Urea, Super phosphate, NPK, some of the soil supplements analysed are cow dung and chicken droppings. Using Atomic Absorption Spectrophotometer (AAS) the following range of heavy metal concentrations were obtained: Cu 3.92-38.14mg/l, Mn 0.057-199.17mg/l, Cr 0.19-2.207mg/l, Zn 1.35-83.12mg/l, Fe 5.00-514.18mg/l, Ni 0.063-149mg/l, Pb 9.86-15.52mg/l, Co 0.26-2.87mg/l.. Super phosphate had the highest abundance of Iron (514.18mg/l). These values were compared to standards for heavy metals in fertilizers and supplements for other countries and were found to be below the limits. Like other countries, it will be important for Nigeria to have set standards for heavy metals levels for fertilizers used in the country.

Global Journal of Pure and Applied Sciences, 2010

The human body uses oils and fats in the diet as an energy source, as a structural component and ... more The human body uses oils and fats in the diet as an energy source, as a structural component and to make powerful biological regulators. The significance of trace metals and toxicological effects of heavy metals on human health and nutrition have been increasingly studied in recent years. Micronutrients play a role in cellular defences, acting both as 'sinks' for free radicals or by being involved in the activity of the enzymes required to deal with the oxidative products e.g. zinc and copper in superoxide dismutase. Presence of metals in edible oil could be from soil or during the manufacturing process. In this present study, the levels of some metals were determined in vegetable oils sold in Zaria, Nigeria. The concentration ranged from 19.

Global Journal of Pure and Applied Sciences, 2010

Electrochimica Acta, 2013

DNA capture surfaces represent a powerful approach to developing highly sensitive sensors for ide... more DNA capture surfaces represent a powerful approach to developing highly sensitive sensors for identifying the cause of infection. Electrochemically deposited polypyrrole, PPy, films have been functionalized with electrodeposited gold nanoparticles to give a nanocomposite material, PPy-AuNP. Thiolated capture strand DNA, that is complementary to the sequence from the pathogen Staphylococcus aureus that causes mammary gland inflammation, was then immobilized onto the gold nanoparticles and any of the underlying gold electrode that is exposed. A probe strand, labelled with horse radish peroxidase, HRP, was then hybridized to the target. The concentration of the target was determined by measuring the current generated by reducing benzoquinone produced by the HRP label. Semi-log plots of the pathogen DNA concentration vs. faradaic current are linear from 150 pM to 1 M and pM concentrations can be detected without the need for molecular, e.g., PCR or NASBA, amplification. The nanocomposite also exhibits excellent selectivity and single base mismatches in a 30 mer sequence can be detected.

Chemistry of Natural Compounds, 2013

The genus Helianthemum Miller belongs to the Cistaceae family [1, 2]. It includes approximately 2... more The genus Helianthemum Miller belongs to the Cistaceae family [1, 2]. It includes approximately 24 species most of which are distributed in the Mediterranean Basin. However, some of them have a more eccentric distribution, some toward Central Asia (H. songoricum schrank), and others toward the north of Europe (H. nummularium (L.) Mill.) H. oelandicum (L.) DC. Mexican traditional folk medicine uses Helianthemum glomeratum as a remedy against gastrointestinal disorders such as diarrhea and dysentery [3]. However, to the best of our knowledge, very few chemical studies of the genus Helianthemum are reported in the literature, and only the essential oil of Helianthemum kahiricum (Del.) has been described [4]. The first results of our chemical investigation on the butanol-liposoluble extract of the aerial parts of the Algerian specimens Helianthemum kahiricum led to the isolation of two natural compounds exhibiting a flavone glycosyl skeleton, kaempferol-3-D-(6-O-trans-p-coumaroyl) glucopyranoside (1) and kaempferol-3-O-(3 ,6 -di-O-trans-p-coumaroyl) glucopyranoside (2), representing new kaempferol derivatives in the family Cistaceae L. These two compounds were fully characterized by spectral methods, mainly NMR techniques. A survey of the literature on kaempferol glycoside showed that 1 is structurally related to the known buddlenoid from Beddeleia coriacea (Loganiacea) [5] and identical to those isolated from Muntingia calabura (Muntingiaceae), Pinus contorta (Pinaceae), Fragaria ananassa, Potentilla chinesis (Rosaceae), and Stenochlaena palustris (Polypodiaceae) [6–10]. Our assignment for compound 2 was in agreement with those reported in the literature for the same compound isolated from Stenochlaena palustris (Polypodiaceae) [9]. Evaluation of the Antimicrobial Activity. The antimicrobial activity of Helianthemum kahiricum was determinated by the diffusion technique on solid media. Strains of human pathogen microorganisms used in this study were as follows: E. coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Enterobacter ESBL, and multidrug-resistant Staphylococcus and Pseudomonas CAZR. The antimicrobial activity is determined by measuring the diameter of the inhibition zone of microbial growth produced around the disks after incubation at 35 C for 24 hours (Table 1). The inhibitory effect on bacterial growth was determined using the agar-disc diffusion assay [11, 12]. According to the results given in Table 1, the butanol crude extract exhibited very strong antimicrobial activity against all tested strains. Moreover, activity was more effective against gram positive than gram negative bacteria, with diameters between 15 and 16 mm for gram-positive bacteria and between 9 and 15 for gram-negative bacteria. The first dilution of the same extract showed activity against Staphylococcus aureus (ATCC) and Staphylococcus aureus (MRSA) (11 mm and 10 mm, respectively). The chloroform extract of Helianthemum kahiricum displayed moderate activities against all the tested bacterial strains, while the petroleum ether extract showed inactivity.

Analytical Methods, 2014

A polypyrrole based potentiometric phosphate biosensor has been fabricated by entrapment of pyruv... more A polypyrrole based potentiometric phosphate biosensor has been fabricated by entrapment of pyruvate oxidase in a polypyrrole film.

The protection of our environment from pollution by various industrial wastes is an extremely imp... more The protection of our environment from pollution by various industrial wastes is an extremely important problem of modern times. Ideally each Industry should treat its effluent by the installation of pollution abatement equipment. A uniform effluent limit has been drawn up for all category of Industrial effluent in Nigeria. Additional effluent limit have been provided for individual industries. Industries have to meet set limits for their effluent and enforcement is by compliance monitoring. An assessment of the performance of primary effluent treatment plant (PETP) of major tanneries in Kano, Nigeria was carried out between January and September 2011using physicochemical and biochemical parameters of water quality. Influent and effluent samples were collected and analyzed according to standard methods. The percentage reduction in pollution load was as follows: 44%, 36%, 39%, 32%, 17%, 34%, 40%, 44%, 53%, 76%, 61%, and 86% for chloride, total dissolved solids, total solids, total su...

The determination of phosphate is of environmental and clinical importance because it is one of t... more The determination of phosphate is of environmental and clinical importance because it is one of the factors associated with eutrophication, which disrupts aquatic life cycles. However, phosphate is also an essential component of all living organisms. Various analytical methods, such as chromatography, colorimetry, optical fluorescent spectroscopy and electrochemical methods have been used for the determination of phosphate. However, these methods require skilled operators, expensive instrumentation, and, in some cases, involve usage of potentially carcinogenic chemicals. In recent years, the use of biosensors has attracted a lot of interest as a simple and rapid alternative to the traditional methods because of their enormous advantages, such as high selectivity, simplicity of use and the possibility for miniaturization. In this thesis, various configurations of phosphate nanobiosensors are reported. The thesis is structured into eight chapters, with Chapter 1 comprising of the gene...

Total hydrocarbon and physicochemical parameters of water quality were investigated in the Calaba... more Total hydrocarbon and physicochemical parameters of water quality were investigated in the Calabar river estuary from January to June. Total hydrocarbon (THC) in surface water was observed to be below detectable limit (0.00mg/l) throughout the study. THC in sediment varied between 15.8mg/g and 130mg/g with a highest mean value of 127.9±3.2mg/g during dry season and between 9.8mg/g and 122.2mg/g with 45.3±66.6 as the highest mean during wet season, indicating a significant increase during the dry season (ANOVA, P < 0.05). THC values also increased significantly downstream from a mean concentration of 26.4 ±92mg/g in station 1 to 127.9± 2.3mg/g in station 4 in the dry season (P<0.05). Dissolved Oxygen (DO) ranged from 1.0mg/l to 7.1mg/l. DO showed significant (P<0.05) spatial variation during dry season. pH ranged between 5.94 and 7.34. Dry season values were significantly higher than wet season measurements (P<0.05). There were significant (P<0.05) spatial variations i...

Trace metal determination in human blood have become important to obtain information regarding th... more Trace metal determination in human blood have become important to obtain information regarding the health status of individuals since blood is a good indicator of current body burden of metals. In this study the levels of Nickel, Manganese, Cobalt and Chromium were determined in whole blood of people of different age groups ranging from 1-40 years residing in Derata, Anka, Nigeria. Thirty-three blood samples were collected from the subjects and analyzed using Atomic Absorption Spectrophotometer after wet digestion. The trace metal levels in mg/l were 0.166±141, 0.935±0.491, 0.318±141 and 1.321±0.376 for Cr, Ni, Mn and Co respectively. The result obtained indicated no significant difference in metal levels between the age groups except for cobalt. Apart from Manganese, the concentrations were found to be above the maximum allowable limits for these metals in human blood. The health implications of these research findings were also discussed.

Zamfara State, Nigeria has a lot of untapped mineral resources. The natives tap these minerals cr... more Zamfara State, Nigeria has a lot of untapped mineral resources. The natives tap these minerals crudely with so many mining sites scattered all over the state. Dareta village is one of such mining fields. Recently, many deaths are being recorded in Anka, Bukkuyum and Maru LGAs of the state. These deaths are attributed to lead poisoning which necessitated immediate remediation by the Nigerian authorities with technical assistance from a coalition of international organizations. Levels of lead, cadmium and copper in soil were investigated in Dareta village, Anka LGA, after the remediation exercise. Lead ranged between 81.65 and 684.27 mg/kg dry weight, Cadmium between 0.02 and 1.88 mg/kg dry weight and Copper between 4.42 and 146.49 mg/kg dry weight. Although the contamination situation was less severe compared to the levels before the remediation exercise, findings from this study shows that Lead, Cadmium and Copper levels in soil are worrying. The need for further attention is obviou...

Many tanneries are located at Sharada Industrial Estate in Kano. these tanneries discharge their ... more Many tanneries are located at Sharada Industrial Estate in Kano. these tanneries discharge their effluents into canals that eventually flow into the Challawa River. Tannery effluents were collected from the effluent confluence point at Sharada Industrial Estate and some physiochemical parameters of the waste water such as total solids, total suspended solids and total dissolved solids, conductivity, alkalinity, chloride, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), sulphide and chromium were determined using the Standard Methods. The concentrations of these parameters were higher than the limits set by the Federal Ministry of Environment (FEMEnv) for discharge of effluents by the Tannery Sector. The tannery effluents from Sharada Industrial Estate pollute the Challawa River in Kano.

The evaluation of metals levels in cow blood is important for assessing the potential effects of ... more The evaluation of metals levels in cow blood is important for assessing the potential effects of pollutants on grazing cattle and for quantifying contaminant intakes by humans. Hence Atomic Absorption Spectrophotometer (AAS) was used to determine trace and heavy metals of toxicological implications in cow blood. Six trace metals (Fe, Zn, Cu, Mn, Ni, Al) were found in a range between 0.18±0.10 to 36.62±7.71ppm and 0.20±0.06 to 35.11±14.78ppm in sample area A and B respectively. Three heavy metals (Cd, Pb, Cr) of toxicological implications were also found to range between 0.12±0.04 to 2.12±1.54 in area A and 0.17±0.14 to 2.81±0.90ppm in study area B. No statistically significant difference was observed between the two study areas for all the elements determined at 95%confidence levels. Except for Cu and Mn the values obtained were higher than the allowable limit for trace elements in blood.

Milk is a very important component of human diet. The presence of toxic element in milk may creat... more Milk is a very important component of human diet. The presence of toxic element in milk may create significant health problems. In this study, metal levels of fresh cow milk were determined. Fresh milk samples were collected from 17 cows grazed around challawa industrial estate, Kano and 9 cows grazed on open fields in Zaria, Kaduna state. Metal levels were determined using Atomic Absorption Spectrophotometer after wet digestion. The result shows the mean concentration of Al, Mn, Ni, Cu, Cd, Pb, Cr, Fe, and Zn in samples from Kano to be 10. respectively. The concentrations were very high as the metal levels of both Kano and Zaria samples exceeded the WHO permissible limits. Except for Pb, Zn and Mn, metal levels of cow milk from Kano were higher than those obtained from Zaria, though the result indicated no statistically significant difference between them. The implication of the results obtained to public health was discussed.

Microchimica Acta, 2015

ABSTRACT The article describes a method for rapid and visual determination of Hg(II) ion using un... more ABSTRACT The article describes a method for rapid and visual determination of Hg(II) ion using unmodified gold nanoparticles (Au-NPs). It involves the addition of Au-NPs to a solution containing Hg(II) ions which, however, does not induce a color change. Next, a solution of lysine is added which induces the aggregation of the Au-NPs and causes the color of the solution to change from wine-red to purple. The whole on-site detection process can be executed in less than 15 min. Other amines (ethylenediamine, arginine, and melamine) were also investigated with respect to their capability to induce aggregation. Notably, only amines containing more than one amino group were found to be effective, but a 0.4 μM and pH 8 solution of lysine was found to give the best results. The detection limits for Hg (II) are 8.4 pM (for instrumental read-out) and 10 pM (for visual read-out). To the best of our knowledge, this LOD is better than those reported for any other existing rapid screening methods. The assay is not interfered by the presence of other common metal ions even if present in 1000-fold excess over Hg(II) concentration. It was successfully applied to the determination of Hg(II) in spiked tap water samples. We perceive that this method provides an excellent tool for rapid and ultrasensitive on-site determination of Hg(II) ions at low cost, with relative ease and minimal operation.

Biosensors & bioelectronics, Jan 14, 2015

A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidas... more A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidase (PyOx) and its cofactors, thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), with a highly ordered gold nanowires array (AuNWA) has been developed. The successful integration of PyOx and the co-factors, via crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLA), onto the AuNWA was confirmed by cyclic voltammetry and amperometry. The resulting nanobiosensor achieved a detection limit of 0.1µM, a linear concentration range of 12.5-1000µM, and a sensitivity of 140.3µAmM(-1)cm(-2). Notably, the incorporation of the AuNWA reduced the required PyOx concentration by 70-120 fold and the presence of common interferants, such as chloride, sulfate, fluoride, nitrite and nitrate ions did not interfere with phosphate detection. Furthermore, the nanobiosensor demonstrated a very high stability with repeated use over two weeks and was successfully used for the determin...

Journal of The Electrochemical Society, 2014

ABSTRACT Well aligned Pt/Au alloy nanowire arrays are successfully synthesized and used as the su... more ABSTRACT Well aligned Pt/Au alloy nanowire arrays are successfully synthesized and used as the substrate for the construction of phosphate biosensors. Pyruvate oxidase is immobilized onto the nanowire surface together with co-factors via cross linking approach. Morphology, composition, structure and chemical state of the nanowires are characterized by SEM, TEM, EDS and XPS, and the electrochemical behaviors of the as-prepared phosphate biosensors are investigated by cyclic voltammogramic and chronoamperometric techniques. Especially, the influence of the composition and aspect ratio of Pt/Au alloy nanowire arrays on the response of phosphate biosensors are studied as well. The present phosphate biosensor shows a high sensitivity of 50.5 μA· cm−2 ·mM−1 and a wide linear range between 248 and 1456 μM toward the detection of phosphate. In addition, the biosensor also exhibits good selectivity and stability, which promises great potential in phosphate detection applications.

Journal of the Electrochemical Society, 2014

ABSTRACT B291 0013-4651/2014/161(14)/B291/6/$31.00 © The Electrochemical Society A hybrid flow in... more ABSTRACT B291 0013-4651/2014/161(14)/B291/6/$31.00 © The Electrochemical Society A hybrid flow injection-nanobiosensor system for the detection of glucose at low potential is presented in this paper. For the fabrication of the biosensor, highly ordered gold nanowire arrays (AuNWAs) are synthesized by direct electrodeposition in combination with tem-plate approach. Glucose oxidase and horseradish peroxidase are immobilized on the surface of the resultant AuNWAs by cross-linking with glutaraldehyde (GLA) and bovine serum albumin (BSA). In combination with a flow injection system, the biosensor demon-strate high performance in glucose detection with a sensitivity of 25.34 μA · cm −2 · mM −1 , a linear range between 5 and 1000 μM, a detection limit of 1 μM, and a sample throughput of 45 h −1 . High selectivity against uric acid, nitrate and chloride ions is also achieved. In addition, it shows good reproducibility, repeatability and stability, which are beneficial for the practical applications in glucose detection. Finally, the developed nanobiosensor is applied to the detection of glucose in river water and the biosensor presents good performance with a relative standard deviation of 1.33% and a recovery rate of 100.4∼102.9%. © 2014 The Electrochemical Society. [DOI: 10.1149/2.0061414jes] All rights reserved.

Journal of Plant Studies, 2012

The composition of fatty acids (FA) and vitamin E in seed oils of Albezia lebbeck (AL), Citrus si... more The composition of fatty acids (FA) and vitamin E in seed oils of Albezia lebbeck (AL), Citrus sinensis (CS), Terminalia catapa (TC), Tamarindus indica (TI) and Citrullus vulgaris (CV) was investigated. The oil yields were obtained by solvent extraction and analysed for fatty acids by Gas Chromatography Mass Spectroscopy (GC-MS). The oil yields of the seeds were found to be 8.

Global Journal of Pure and Applied Sciences, 2006

Global Journal of Pure and Applied Sciences, 2009

The heavy metal composition of some commercial fertilizers and soil supplements used in Zaria wer... more The heavy metal composition of some commercial fertilizers and soil supplements used in Zaria were analysed. The fertilizers analysed include Liquid Organic fertilizer, Palette Organic fertilizer, Urea, Super phosphate, NPK, some of the soil supplements analysed are cow dung and chicken droppings. Using Atomic Absorption Spectrophotometer (AAS) the following range of heavy metal concentrations were obtained: Cu 3.92-38.14mg/l, Mn 0.057-199.17mg/l, Cr 0.19-2.207mg/l, Zn 1.35-83.12mg/l, Fe 5.00-514.18mg/l, Ni 0.063-149mg/l, Pb 9.86-15.52mg/l, Co 0.26-2.87mg/l.. Super phosphate had the highest abundance of Iron (514.18mg/l). These values were compared to standards for heavy metals in fertilizers and supplements for other countries and were found to be below the limits. Like other countries, it will be important for Nigeria to have set standards for heavy metals levels for fertilizers used in the country.

Global Journal of Pure and Applied Sciences, 2010

The human body uses oils and fats in the diet as an energy source, as a structural component and ... more The human body uses oils and fats in the diet as an energy source, as a structural component and to make powerful biological regulators. The significance of trace metals and toxicological effects of heavy metals on human health and nutrition have been increasingly studied in recent years. Micronutrients play a role in cellular defences, acting both as 'sinks' for free radicals or by being involved in the activity of the enzymes required to deal with the oxidative products e.g. zinc and copper in superoxide dismutase. Presence of metals in edible oil could be from soil or during the manufacturing process. In this present study, the levels of some metals were determined in vegetable oils sold in Zaria, Nigeria. The concentration ranged from 19.

Global Journal of Pure and Applied Sciences, 2010

Electrochimica Acta, 2013

DNA capture surfaces represent a powerful approach to developing highly sensitive sensors for ide... more DNA capture surfaces represent a powerful approach to developing highly sensitive sensors for identifying the cause of infection. Electrochemically deposited polypyrrole, PPy, films have been functionalized with electrodeposited gold nanoparticles to give a nanocomposite material, PPy-AuNP. Thiolated capture strand DNA, that is complementary to the sequence from the pathogen Staphylococcus aureus that causes mammary gland inflammation, was then immobilized onto the gold nanoparticles and any of the underlying gold electrode that is exposed. A probe strand, labelled with horse radish peroxidase, HRP, was then hybridized to the target. The concentration of the target was determined by measuring the current generated by reducing benzoquinone produced by the HRP label. Semi-log plots of the pathogen DNA concentration vs. faradaic current are linear from 150 pM to 1 M and pM concentrations can be detected without the need for molecular, e.g., PCR or NASBA, amplification. The nanocomposite also exhibits excellent selectivity and single base mismatches in a 30 mer sequence can be detected.

Chemistry of Natural Compounds, 2013

The genus Helianthemum Miller belongs to the Cistaceae family [1, 2]. It includes approximately 2... more The genus Helianthemum Miller belongs to the Cistaceae family [1, 2]. It includes approximately 24 species most of which are distributed in the Mediterranean Basin. However, some of them have a more eccentric distribution, some toward Central Asia (H. songoricum schrank), and others toward the north of Europe (H. nummularium (L.) Mill.) H. oelandicum (L.) DC. Mexican traditional folk medicine uses Helianthemum glomeratum as a remedy against gastrointestinal disorders such as diarrhea and dysentery [3]. However, to the best of our knowledge, very few chemical studies of the genus Helianthemum are reported in the literature, and only the essential oil of Helianthemum kahiricum (Del.) has been described [4]. The first results of our chemical investigation on the butanol-liposoluble extract of the aerial parts of the Algerian specimens Helianthemum kahiricum led to the isolation of two natural compounds exhibiting a flavone glycosyl skeleton, kaempferol-3-D-(6-O-trans-p-coumaroyl) glucopyranoside (1) and kaempferol-3-O-(3 ,6 -di-O-trans-p-coumaroyl) glucopyranoside (2), representing new kaempferol derivatives in the family Cistaceae L. These two compounds were fully characterized by spectral methods, mainly NMR techniques. A survey of the literature on kaempferol glycoside showed that 1 is structurally related to the known buddlenoid from Beddeleia coriacea (Loganiacea) [5] and identical to those isolated from Muntingia calabura (Muntingiaceae), Pinus contorta (Pinaceae), Fragaria ananassa, Potentilla chinesis (Rosaceae), and Stenochlaena palustris (Polypodiaceae) [6–10]. Our assignment for compound 2 was in agreement with those reported in the literature for the same compound isolated from Stenochlaena palustris (Polypodiaceae) [9]. Evaluation of the Antimicrobial Activity. The antimicrobial activity of Helianthemum kahiricum was determinated by the diffusion technique on solid media. Strains of human pathogen microorganisms used in this study were as follows: E. coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Enterobacter ESBL, and multidrug-resistant Staphylococcus and Pseudomonas CAZR. The antimicrobial activity is determined by measuring the diameter of the inhibition zone of microbial growth produced around the disks after incubation at 35 C for 24 hours (Table 1). The inhibitory effect on bacterial growth was determined using the agar-disc diffusion assay [11, 12]. According to the results given in Table 1, the butanol crude extract exhibited very strong antimicrobial activity against all tested strains. Moreover, activity was more effective against gram positive than gram negative bacteria, with diameters between 15 and 16 mm for gram-positive bacteria and between 9 and 15 for gram-negative bacteria. The first dilution of the same extract showed activity against Staphylococcus aureus (ATCC) and Staphylococcus aureus (MRSA) (11 mm and 10 mm, respectively). The chloroform extract of Helianthemum kahiricum displayed moderate activities against all the tested bacterial strains, while the petroleum ether extract showed inactivity.

Analytical Methods, 2014

A polypyrrole based potentiometric phosphate biosensor has been fabricated by entrapment of pyruv... more A polypyrrole based potentiometric phosphate biosensor has been fabricated by entrapment of pyruvate oxidase in a polypyrrole film.

The protection of our environment from pollution by various industrial wastes is an extremely imp... more The protection of our environment from pollution by various industrial wastes is an extremely important problem of modern times. Ideally each Industry should treat its effluent by the installation of pollution abatement equipment. A uniform effluent limit has been drawn up for all category of Industrial effluent in Nigeria. Additional effluent limit have been provided for individual industries. Industries have to meet set limits for their effluent and enforcement is by compliance monitoring. An assessment of the performance of primary effluent treatment plant (PETP) of major tanneries in Kano, Nigeria was carried out between January and September 2011using physicochemical and biochemical parameters of water quality. Influent and effluent samples were collected and analyzed according to standard methods. The percentage reduction in pollution load was as follows: 44%, 36%, 39%, 32%, 17%, 34%, 40%, 44%, 53%, 76%, 61%, and 86% for chloride, total dissolved solids, total solids, total su...