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Publication

Gold nanoparticle sensor for the visual detection of pork adulteration in meatball formulation

( 2011-06-30)

Ali, Mohamad Eaqub

;

Uda Hashim

;

S. Mustafa

;

Y. B. Che Man

;

Kh. N. Islam

We visually identify pork adulteration in beef and chicken meatball preparations using 20 nm gold nanoparticles (GNPs) as colorimetric sensors. Meatball is a popular food in certain Asian and European countries. Verification of pork adulteration in meatball is necessary to meet the Halal and Kosher food standards. Twenty nm GNPs change color from pinkish-red to gray-purple, and their absorption peak at 525 nm is red-shifted by 30–50 nm in 3 mM phosphate buffer saline (PBS). Adsorption of single-stranded DNA protects the particles against salt-induced aggregation. Mixing and annealing of a 25-nucleotide (nt) single-stranded (ss) DNA probe with denatured DNA of different meatballs differentiated well between perfectly matched and mismatch hybridization at a critical annealing temperature. The probes become available in nonpork DNA containing vials due to mismatches and interact with GNPs to protect them from salt-induced aggregation. Whereas, all the pork containing vials, either in pure and mixed forms, consumed the probes totally by perfect hybridization and turned into grey, indicating aggregation. This is clearly reflected by a well-defined red-shift of the absorption peak and significantly increased absorbance in 550–800 nm regimes. This label-free low-cost assay should find applications in food analysis, genetic screening, and homology studies.

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Publication

Modular architecture of a non-contact pinch actuation micropump

( 2012)

Pei Song Chee

;

Rashidah Arsat

;

Tijjani Adam

;

Uda Hashim

;

Ruzairi Abdul Rahim

;

Pei Ling Leow

This paper demonstrates a modular architecture of a non-contact actuation micropump setup. Rapid hot embossing prototyping was employed in micropump fabrication by using printed circuit board (PCB) as a mold material in polymer casting. Actuator-membrane gap separation was studied, with experimental investigation of three separation distances: 2.0 mm, 2.5 mm and 3.5 mm. To enhance the micropump performance, interaction surface area between plunger and membrane was modeled via finite element analysis (FEA). The micropump was evaluated against two frequency ranges, which comprised a low driving frequency range (0–5 Hz, with 0.5 Hz step increments) and a nominal frequency range (0–80 Hz, with 10 Hz per step increments). The low range frequency features a linear relationship of flow rate with the operating frequency function, while two magnitude peaks were captured in the flow rate and back pressure characteristic in the nominal frequency range. Repeatability and reliability tests conducted suggest the pump performed at a maximum flow rate of 5.78 mL/min at 65 Hz and a backpressure of 1.35 kPa at 60 Hz.

Publication

A potentiometric indirect uric acid sensor based on ZnO nanoflakes and immobilized uricase

( 2012)

Syed M. Usman Ali

;

Zafar Hussain Ibupoto

;

Muhammad Kashif

;

Uda Hashim

;

Magnus Willander

In the present work zinc oxide nanoflakes (ZnO-NF) structures with a wall thickness around 50 to 100 nm were synthesized on a gold coated glass substrate using a low temperature hydrothermal method. The enzyme uricase was electrostatically immobilized in conjunction with Nafion membrane on the surface of well oriented ZnO-NFs, resulting in a sensitive, selective, stable and reproducible uric acid sensor. The electrochemical response of the ZnO-NF-based sensor vs. a Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (500 nM to 1.5 mM). In addition, the ZnO-NF structures demonstrate vast surface area that allow high enzyme loading which results provided a higher sensitivity. The proposed ZnO-NF array-based sensor exhibited a high sensitivity of ~66 mV/ decade in test electrolyte solutions of uric acid, with fast response time. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea

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Publication

Food assimilated by two sympatric populations of the brown planthopper Nilaparvata lugens (Delphacidae) feeding on different host plants contaminates insect DNA detected by RAPD-PCR analysis

( 2012)

M.A. Latif

;

M.Y. Omar

;

S.G. Tan

;

S.S. Siraj

;

Ali, Mohamad Eaqub

;

M.Y. Rafii

Contamination of insect DNA for RAPD-PCR analysis can be a problem because many primers are non-specific and DNA from parasites or gut contents may be simultaneously extracted along with that of the insect. We measured the quantity of food ingested and assimilated by two sympatric populations of brown planthopper (BPH), Nilaparvata lugens, one from rice and the other from Leersia hexandra (Poaceae), a wetland forage grass, and we also investigated whether host plant DNA contaminates that of herbivore insects in extractions of whole insects. Ingestion and assimilation of food were reduced significantly when individuals derived from one host plant were caged on the other species. The bands, OPA3 (1.25), OPD3 (1.10), OPD3 (0.80), OPD3 (0.60), pUC/M13F (0.35), pUC/M13F (0.20), BOXAIR (0.50), peh#3 (0.50), and peh#3 (0.17) were found in both rice-infesting populations of brown planthopper and its host plant (rice). Similarly, the bands, OPA4 (1.00), OPB10 (0.70), OPD3 (0.90), OPD3 (0.80), OPD3 (0.60), pUC/ M13F (0.35), pUC/M13F (0.20), and BOXAIR (0.50) were found in both Leersia-infesting populations of brown planthopper and the host plant. So, it is clear that the DNA bands amplified in the host plants were also found in the extracts from the insects feeding on them.

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Publication

Effect of manganese content on the fabrication of porous anodic alumina

( 2012)

Voon Chun Hong

;

M. N. Derman

;

Uda Hashim

The influence of manganese content on the formation of well-ordered porous anodic alumina was studied. Porous anodic alumina has been produced on aluminium substrate of different manganese content by single-step anodizing at 50 V in 0.3 M oxalic acid at 15°C for 60 minutes. The well-ordered pore and cell structure was revealed by subjecting the porous anodic alumina to oxide dissolution treatment in a mixture of chromic acid and phosphoric acid. It was found that the manganese content above 1 wt% impaired the regularity of the cell and pore structure significantly, which can be attributed to the presence of secondary phases in the starting material with manganese content above 1 wt%. The pore diameter and interpore distance decreased with the addition of manganese into the substrates. The time variation of current density and the thickness of porous anodic alumina also decreased as a function of the manganese content in the substrates.

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Publication

Nanobioprobe for the determination of pork adulteration in burger formulations

( 2012-02-14)

Mohamad Eaqub Ali

;

S. Mustafa

;

Uda Hashim

;

Y. B. Che Man

;

K. L. Foo

We report the development of a swine-specific hybrid nanobioprobe through a covalent integration of a fluorophore-labeled 27-nucleotideAluI-fragment of swine cytochrome b gene to a 3 nm gold nanoparticle for the determination of pork adulteration in processed meat products. We tested the probe to estimate adulterated pork in ready-to-eat pork-spiked beef burgers. The probe quantitatively detected 1–100% spiked pork in burger formulations with ≥90% accuracy. A plot of observed fluorescence against the known concentration ofAluI-digested pork DNA targets generated a concave curve, demonstrating a power relationship (y=2.956x0.509) with a regression coefficient (R2) of 0.986. No cross-species detection was found in a standard set of pork, beef, chicken, mutton, and chevon burgers. The method is suitable for the determination of very short-length nucleic acid targets which cannot be estimated by conventional and real-time PCR but are essential for the determination of microRNA in biodiagnostics and degraded DNA in forensic testing and food analysis.

Publication

Fabrication of silicon nitride ion sensitive field-effect transistor for pH measurement and DNA Immobilization/Hybridization

( 2013)

Uda Hashim

;

Soon Weng Chong

;

Liu Wei Wen

The fabrication of ion sensitive field-effect transistor (ISFET) using silicon nitride (Si3N4) as the sensing membrane for pH measurement and DNA is reported. For the pH measurement, the Ag/AgCl electrode was used as the reference electrode, and different pH values of buffer solution were used in the ISFET analysis. The ISFET device was tested with pH buffer solutions of pH2, pH3, pH7, pH8, and pH9. The results show that the IV characteristic of ISFET devices is directly proportional and the device’s sensitivity was 43.13 mV/pH. The ISFET is modified chemically to allow the integration with biological element to form a biologically active field-effect transistor (BIOFET). It was found that the DNA immobilization activities which occurred on the sensing membrane caused the drain current to drop due to the negatively charged backbones of the DNA probes repelled electrons from accumulating at the conducting channel. The drain current was further decreased when the DNA hybridization took place.

Publication

Comparative reliability studies and analysis of Au, Pd-Coated Cu and Pd-Doped Cu Wire in microelectronics packaging

( 2013)

Gan Chong Leong

;

Uda Hashim

;

Vipul Bansal

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (D o ) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, b of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

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Publication

Precise alignment of individual single-walled carbon nanotube using dielectrophoresis method for development and fabrication of pH sensor

( 2013)

Uda Hashim

;

Foo Wah Low

;

Liu Wei Wen

Development and fabrication of single-walled carbon nanotube (SWNT) based pH sensor were reported. The precise alignment of individual SWNT using dielectrophoresis method between the two microgap electrodes was conducted, and the effects of precise alignment of individual SWNT on impedance, long term stability, and capacitance of the sensor were studied. The pH sensor was fabricated using conventional photolithography and wet etching process. The impedance values were found to decrease in the order of distilled water > pH 10 > pH 5 > pH 3 > air. Without the alignment of SWNT, the capacitances values decreased with increasing of pH values at low frequency. All the impedance and capacitance results were highly repeatable.

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Publication

Morphological, structural, and electrical characterization of sol-gel-synthesized ZnO nanorods

( 2013-02-03)

M. Kashif

;

Uda Hashim

;

M. E. Ali

;

Foo Kai Loong

;

Syed M. Usman Ali

ZnO nanorods were grown on thermally oxidized p-type silicon substrate using sol-gel method. The SEM image revealed high-density, well-aligned, and perpendicular ZnO nanorods on the oxidized silicon substrate. The XRD profile confirmed thec-axis orientation of the nanorods. PL measurements showed the synthesized ZnO nanorods have strong ultraviolet (UV) emission. The electrical characterization was performed using interdigitated silver electrodes to investigate the stability in the current flow of the fabricated device under different ultraviolet (UV) exposure times. It was notified that a stable current flow was observed after 60 min of UV exposure. The determination of stable current flow after UV exposure is necessary for UV-based gas sensing and optoelectronic devices.

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Publication

Impact of hydrogen concentrations on the impedance spectroscopic behavior of Pd-sensitized ZnO nanorods

( 2013-02-11)

Muhammad Kashif

;

Md Eaqub Ali

;

Syed M Usman Ali

;

Uda Hashim

;

Sharifah Bee Abd Hamid

ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance (Rgb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra.

Publication

Effect of temperature of oxalic acid on the fabrication of porous anodic alumina from A1-Mn alloys

( 2013-04-12)

Voon Chun Hong

;

Mohd Nazree Derman

;

Uda Hashim

;

K. R. Ahmad

;

Foo Kai Loong

The influence of temperature of oxalic acid on the formation of well-ordered porous anodic alumina on Al-0.5 wt% Mn alloys was studied. Porous anodic alumina has been produced on Al-0.5 wt% Mn substrate by single-step anodising at 50 V in 0.5 M oxalic acid at temperature ranged from 5°C to 25°C for 60 minutes. The steady-state current density increased accordingly with the temperature of oxalic acid. Hexagonal pore arrangement was formed on porous anodic alumina that was formed in oxalic acid of 5, 10 and 15°C while disordered porous anodic alumina was formed in oxalic acid of 20 and 25°C. The temperature of oxalic acid did not affect the pore diameter and interpore distance of porous anodic alumina. Both rate of increase of thickness and oxide mass increased steadily with increasing temperature of oxalic acid, but the current efficiency decreased as the temperature of oxalic acid increased due to enhanced oxide dissolution from pore wall.

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Publication

Reliability assessment and activation energy study of au and pd-coated cu wires post high temperature aging in nanoscale semiconductor packaging

( 2013-06)

C. L. Gan

;

Uda Hashim

Wearout reliability and high temperature storage life (HTSL) activation energy of Au and Pd-coated Cu (PdCu) ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the influence of wire type on the wearout reliability performance of Au and PdCu wire used in fine pitch BGA package after HTSL stress at various aging temperatures. Failure analysis has been conducted to identify the failure mechanism after HTSL wearout conditions for Au and PdCu ball bonds. Apparent activation energies (Eaa) of both wire types are investigated after HTSL test at 150 °C, 175 °C and 200 °C aging temperatures. Arrhenius plot has been plotted for each ball bond types and the calculated Eaa of PdCu ball bond is 0.85 eV and 1.10 eV for Au ball bond in 110 nm semiconductor device. Obviously Au ball bond is identified with faster IMC formation rate with IMC Kirkendall voiding while PdCu wire exhibits equivalent wearout and or better wearout reliability margin compare to conventional Au wirebond. Lognormal plots have been established and its mean to failure (t50) have been discussed in this paper.

Publication

Synthesis of single-walled carbon nanotubes: effects of active metals, catalyst supports, and metal loading percentage

( 2013-06-27)

Liu Wei Wen

;

Siang-Piao Chai

;

Abdul Rahman Mohamed

;

Uda Hashim

;

Azizan Aziz

The effects of active metals, catalyst supports, and metal loading percentage on the formation of single-walled carbon nanotubes (SWNTs) were studied. In particular, iron, cobalt, and nickel were investigated for SWNTs synthesis. Iron was found to grow better-quality SWNTs compared to cobalt and nickel. To study the effect of catalyst supports, magnesium oxide, silicon oxide, and aluminium oxide were chosen for iron. Among the studied supports, MgO was identified to be a suitable support for iron as it produced SWNTs with better graphitisation determined by Raman analysis. Increasing the iron loading decreased the quality of SWNTs due to extensive agglomeration of the iron particles. Thus, lower metal loading percentage is preferred to grow better-quality SWNTs with uniform diameters.

1 13

Publication

Structural, optical, electrical, and photoresponse properties of postannealed Sn-Doped ZnO nanorods

( 2013-11-28)

Q. Humayun

;

M. Kashif

;

Uda Hashim

Tin (Sn) doped ZnO nanorods were synthesized on glass substrate using a sol-gel method. The synthesized nanorods were postannealed at 150, 350, and 500°C. The surface morphologies of Sn-doped ZnO nanorods at different postannealing temperatures were studied using scanning electron microscope (SEM). XRD results show that as the postannealing temperature increased from 150°C to 500°C, thec-axis orientation becomes stronger. Refractive indices and dielectric constants were calculated on the basis of different relationships by utilizing bandgap values. These bandgap values were obtained in terms of optical absorption by using a UV-Visible spectrophotometer. The enhancing effects of annealing temperatures on electrical properties were observed in terms of current-to-voltage measurements. Resistivity decreases as postannealing temperature increases from 150°C to 500°C. Annealed samples were evaluated for UV-sensing application. The samples exhibit a responsivity of 1.7 A/W

Publication

Titanium dioxide nanoparticle-based interdigitated electrodes: A novel current to voltage DNA biosensor recognizes E. coli O157:H7

( 2015)

Sh. Nadzirah

;

N. Azizah

;

Uda Hashim

;

Subash Chandra Bose Gopinath

;

Mohd Kashif

Nanoparticle-mediated bio-sensing promoted the development of novel sensors in the front of medical diagnosis. In the present study, we have generated and examined the potential of titanium dioxide (TiO 2) crystalline nanoparticles with aluminium interdigitated electrode biosensor to specifically detect single-stranded E.coli O157:H7 DNA. The performance of this novel DNA biosensor was measured the electrical current response using a picoam-meter. The sensor surface was chemically functionalized with (3-aminopropyl) triethoxysi-lane (APTES) to provide contact between the organic and inorganic surfaces of a single-stranded DNA probe and TiO 2 nanoparticles while maintaining the sensing system’s physi-cal characteristics. The complement of the target DNA of E. coli O157:H7 to the carboxyl-ate-probe DNA could be translated into electrical signals and confirmed by the increased conductivity in the current-to-voltage curves. The specificity experiments indicate that the biosensor can discriminate between the complementary sequences from the base-mis-matched and the non-complementary sequences. After duplex formation, the complemen-tary target sequence can be quantified over a wide range with a detection limit of 1.0 x 10 -13 M. With target DNA from the lysed E. coli O157:H7, we could attain similar sensitivity. Sta-bility of DNA immobilized surface was calculated with the relative standard deviation (4.6%), displayed the retaining with 99% of its original response current until 6 months. This high-performance interdigitated DNA biosensor with high sensitivity, stability and non-foul-ing on a novel sensing platform is suitable for a wide range of biomolecular interactive analyses.

Publication

Revealing glycoproteins in the secretome of MCF-7 human breast cancer cells

( 2015)

Aik-Aun Tan

;

Wai-Mei Phang

;

Subash Chandra Bose Gopinath

;

Onn H. Hashim

;

Lik Voon Kiew

;

Yeng Chen

Breast cancer is one of the major issues in the field of oncology, reported with a higher prevalence rate in women worldwide. In attempt to reveal the potential biomarkers for breast cancer, the findings of differentially glycosylated haptoglobin and osteonectin in previous study have drawn our attention towards glycoproteins of secretome from the MCF-7 cancer cell line. In the present study, further analyses were performed on the medium of MCF-7 cells by subjecting it to two-dimensional analyses followed by image analysis in contrast to the medium of human mammary epithelial cells (HMEpC) as a negative control. Carboxypeptidase A4 (CPA4), alpha-1-antitrypsin (AAT), haptoglobin (HP), and HSC70 were detected in the medium of MCF-7, while only CPA4 and osteonectin (ON) were detected in HMEpC medium. In addition, CPA4 was detected as upregulated in the MCF-7 medium. Further analysis by lectin showed that CPA4, AAT, HP, and HSC70 were secreted as N-glycan in the medium of MCF-7, with HP also showing differentially N-glycosylated isoforms. For the HMEpC, only CPA4 was detected as N-glycan. No O-glycan was detected in the medium of HMEpC but MCF-7 expressed O-glycosylated CPA4 and HSC70. All these revealed that glycoproteins could be used as glycan-based biomarkers for the prognosis of breast cancer

Publication

A novel disposable biosensor based on SiNWs/AuNPs modified-screen printed electrode for dengue virus DNA oligomer detection

( 2015)

Jahwarhar Izuan Abd Rashid

;

Nor Azah Yusof

;

Jaafar Abdullah

;

Uda Hashim

;

Reza Hajian

In this paper, a disposable screen-printed gold electrode (SPGE) utilized of silicon nanowires (SiNWs) and gold nanoparticles as sensing material was fabricated for detection of DNA oligomers related to dengue virus. First, SiNWs/AuNPs-SPGE was developed by the dispersion of SiNWs in 3-aminopropyltriethoxysilane (0.5%) onto bare SPGE. Second, the AuNPs decoration on SiNWs-SPGE surface was functionalized using dithiopropionic acid through a self-assembly monolayer technique. The electrochemical response of methylene blue (MB) as a redox indicator toward synthetic DNA oligomer after hybridization on SiNWs/AuNPs-SPGE was recorded by cyclic voltammetry and differential pulse voltammetry techniques. The results demonstrated that the reduction peak current of MB was significantly decreased after DNA hybridization process. In addition, the developed biosensor showed a good storage stability and could achieve a linear range of 1 × 10−11 − 1 × 10−7 M (R = 0.98) with the detection limit of 1.63 × 10−12 M.

3 9

Publication

Surface modifications to boost sensitivities of electrochemical biosensors using gold nanoparticles/silicon nanowires and response surface methodology approach

( 2015)

Jahwarhar Izuan Abdul Rashid

;

Nor Azah Yusof

;

Jaafar Abdullah

;

Uda Hashim

;

Reza Hajian

3 5

Publication

Momordica charantia fruit mediated green synthesis of silver nanoparticles

( 2015)

Mst Kamrun Nahar

;

Zarina Zakaria

;

Uda Hashim

;

Md Fazlul Bari

The synthesis of nanoparticles (NP) is in the spotlight of modern nanotechnology. In recent years, the development of competent green chemistry methods for the synthesis of metal NPs has become the main focus of research. The biological synthesis of NPs using plant extract is currently under exploitation. For the first time, in this paper, we report the green synthesis of silver nan-oparticles (AgNPs) by reduction of silver nitrate, using fruit extracts of Momordica charantia Linn (bitter melon), a commonly found plant in southeast Asia. The reaction process for the synthesis of AgNPs is simple, cost-effective, novel, rapid and an eco-friendly route using the fruit extracts of M. charantia plant, which acts simultaneously as a reducing and tabilizing agent at room temperature. The formation of the AgNPs was confirmed by surface Plasmon spectra using UV-Vis spectrophotometer and an absorbance peak at 440 nm. To optimize the biosynthesis of AgNPs, the effect of the process variables such as contact time, silver ion concentration and fruit extract quantity were also investigated. The prepared NPs properties were characterized by UV-Vis spectrophotometer, Fourier trans-formed infrared (FTIR) spectroscopy, and TEM analysis.

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