Th. S. Dhahi

Analysis of pork adulteration in commercial meatballs targeting porcine-specific mitochondrial cytochrome b gene by TaqMan probe real-time polymerase chain reaction

A test for assessing pork adulteration in meatballs, using TaqMan probe real-time polymerase chain reaction, was developed. The assay combined porcine-specific primers and TaqMan probe for the detection of a 109 bp fragment of porcine cytochrome b gene. Specificity test with 10 ng DNA of eleven different species yielded a threshold cycle (Ct) of 15.5 ± 0.20 for the pork and negative results for the others. Analysis of beef meatballs with spiked pork showed the assay can determine 100-0.01% contaminated pork with 102% PCR efficiency, high linear regression (r(2) = 0.994) and ≤ 6% relative errors. Residuals analysis revealed a high precision in all determinations. Random analysis of commercial meatballs from pork, beef, chicken, mutton and goat, yielded a Ct between 15.89 ± 0.16 and 16.37 ± 0.22 from pork meatballs and negative results from the others, showing the suitability of the assay to determine pork in commercial meatballs with a high accuracy and precision.

Nanobiosensor for detection and quantification of DNA sequences in degraded mixed meats

A novel class of nanobiosensor was developed by integrating a 27-nucleotide AluI fragment of swine cytochrome b (cytb) gene to a 3-nm diameter citrate-tannate coated gold nanoparticle (GNP). The biosensor detected 0.5% and 1% pork in raw and 2.5- h autoclaved pork-beef binary admixtures in a single step without any separation or washing. The hybridization kinetics of the hybrid sensor was studied with synthetic and AluI digested real pork targets from moderate to extreme target concentrations and a sigmoidal relationship was found. Using the kinetic curve, a convenient method for quantifying and counting target DNA copy number was developed. The accuracy of the method was over 90% and 80% for raw and autoclaved pork-beef binary admixtures in the range of 5-100% pork adulteration. The biosensor probe identified a target DNA sequence that was several-folds shorter than a typical PCR-template. This offered the detection and quantitation of potential targets in highly processed or degraded samples where PCR amplification was not possible due to template crisis. The assay was a viable alternative approach of qPCR for detecting, quantifying and counting copy number of shorter size DNA sequences to address a wide ranging biological problem in food industry, diagnostic laboratories and forensic medicine.

Fabrication of lateral polysilicon gap of less than 50 nm using conventional lithography

We report a thermal oxidation process for the fabrication of nanogaps of less than 50 nmin dimension. Nanogaps of this dimension are necessary to eliminate contributions from double-layer capacitance in the dielectric detection of protein or nucleic acid. The method combines conventional photolithography and pattern-size reduction techniques. The gaps are fabricated on polysilicon-coated silicon substrate with gold electrodes. The dimensions of the structure are determined by scanning electron microscopy (SEM). An electrical characterization of the structures by dielectric analyzer (DA) shows an improved conductivity as well as enhanced permittivity and capacity with the reduction of gap size, suggesting its potential applications in the detection of biomolecule with very low level of power supply. Two chrome Masks are used to complete the work: the first Mask is for the nanogap pattern and the second one is for the electrodes. An improved resolution of pattern size is obtained by controlling the oxidation time. The method expected to enable fabrication of nanogaps with a wide ranging designs and dimensions on different substrates. It is a simple and cost-effective method and does not require complicated nanolithography process for fabricating desired nanogaps in a reproducible fashion.

pH sensing using in house fabricated polysilicon nanoelectrode based transducer

The biological and medical fields have taken the full advantage of nanotechnology in the development of transducers and biochips which are capable of characterizing bio-molecules. The research about the characterisation of nanoelectrode transducer using biomolecule detection technique has been studied to understand the important relationship between the transducer and the nanostructure which leads to high sensitivity and selectivity. We have applied conventional photolithography technique by using polysilicon on silicon substrate to fabricate a nanoelectrode transducer and employed as an electrochemical microelectrode sensors to measure the bio-molecules electrical characteristics. RIE and LPCVD processes were used during the transducer fabrication. Characterization is made both physically and electrically to check the surface topography and the electrical characteristics such as capacitance and conductance. Purchased pH buffer solutions which varied from pH1 to pH12 is dropped on the nanoelectrode and the effect on it is investigated for the application in pH measurement. This research has proven that increase in pH concentration is proportional with capacitance.

Synthesis of zinc oxide thin films prepared by sol-gel for specific bioactivity

Zinc oxide (ZnO) thin films this device to used for many application like chemical sensor, biosensor, solar energy, etc but my project to use for bioactivity(biosensor). Zinc oxide (ZnO) thin films have been grown using sol-gel technique. Characterization was done using Scanning Electron Microscope (SEM), Energy Dispersive X-ray(EDX) and Electrical Measurement(I-V). ZnO thin film was successfully synthesized using low cost sol-gel spin coating method. The coupling of DNA probe to ZnO thin film supports modified with carboxylic acid (COOH) is certainly the best practical method to make DNA immobilization and it does not require any coupling agent which could be a source of variability during the spotting with an automatic device. So, selected this coupling procedure for further experiments. The sensor was tested with initial trial with low concentrated DNA and able to detect detection of the disease effectively. Silicon-on-insulator (SOI) wafer device with ZnO can detect at different concentration in order to valid the device capabilities for detecting development. The lowest concentration 1 µM HPV DNA probe can detect is 0.1 nM HPV target DNA.Zinc oxide (ZnO) thin films this device to used for many application like chemical sensor, biosensor, solar energy, etc but my project to use for bioactivity(biosensor). Zinc oxide (ZnO) thin films have been grown using sol-gel technique. Characterization was done using Scanning Electron Microscope (SEM), Energy Dispersive X-ray(EDX) and Electrical Measurement(I-V). ZnO thin film was successfully synthesized using low cost sol-gel spin coating method. The coupling of DNA probe to ZnO thin film supports modified with carboxylic acid (COOH) is certainly the best practical method to make DNA immobilization and it does not require any coupling agent which could be a source of variability during the spotting with an automatic device. So, selected this coupling procedure for further experiments. The sensor was tested with initial trial with low concentrated DNA and able to detect detection of the disease effectively. Silicon-on-insulator (SOI) wafer device with ZnO can detect at different concentration in order...

Lab-on-chip components for molecular detection

We successfully fabricated Lab on chip components and integrated for possible use in biomedical application. The sensor was fabricated by using conventional photolithography method integrated with PDMS micro channels for smooth delivery of sample to the sensing domain. The sensor was silanized and aminated with 3-Aminopropyl triethoxysilane (APTES) to functionalize the surface with biomolecules and create molecular binding chemistry. The resulting Si-O-Si- components were functionalized with oligonucleotides probe of HPV, which interacted with the single stranded HPV DNA target to create a field across on the device. The fabrication, immobilization and hybridization processes were characterized with current voltage (I-V) characterization (KEITHLEY, 6487). The sensor show selectivity for the HPV DNA target in a linear range from concentration 0.1 nM to 1 µM. This strategy presented a simple, rapid and sensitive platform for HPV detection and would become a powerful tool for pathogenic microorganisms screening in clinical diagnosis.We successfully fabricated Lab on chip components and integrated for possible use in biomedical application. The sensor was fabricated by using conventional photolithography method integrated with PDMS micro channels for smooth delivery of sample to the sensing domain. The sensor was silanized and aminated with 3-Aminopropyl triethoxysilane (APTES) to functionalize the surface with biomolecules and create molecular binding chemistry. The resulting Si-O-Si- components were functionalized with oligonucleotides probe of HPV, which interacted with the single stranded HPV DNA target to create a field across on the device. The fabrication, immobilization and hybridization processes were characterized with current voltage (I-V) characterization (KEITHLEY, 6487). The sensor show selectivity for the HPV DNA target in a linear range from concentration 0.1 nM to 1 µM. This strategy presented a simple, rapid and sensitive platform for HPV detection and would become a powerful tool for pathogenic microorganisms screen...

Lattices parameter dependent on effective atomic interactive coefficient in nanostructure

The usage of thick silicon substrates is widespread in electronic industries todays, silicon is the most important material in the semiconductor industries due to its excellent electrical, mechanical and chemical properties. Due to it being inert at room temperature and having anisotropic properties (electrical, mechanical chemical), silicon plays an important role in micro-electro-mechanical systems (MEMS) application. However, atomic interaction becoming complicated as the number of electrons increases. Atomic interaction beyond the hydrogen atom is indeed complex but quite possible by Schrodinger equation. Therefore, combination of models to explain atomic interaction via density functional theory, Kohn Sham and generalized gradient approximation is proposed. It its expected that the SiNW will show band gap transition with the decreasing size and the band gap properties under inter atomic stress. With this, it is possible to determine the atomic structure of nanowire fundamental behavior. Thus, Based o...

Optimization and validation of highly selective microfluidic integrated silicon nanowire chemical sensor

The study proposed characterization and optimization of silicon nanosensor for specific detection of heavy metal. The sensor was fabricated in-house and conventional photolithography coupled with size reduction via dry etching process in an oxidation furnace. Prior to heavy metal heavy metal detection, the capability to aqueous sample was determined utilizing serial DI water at various. The sensor surface was surface modified with Organofunctional alkoxysilanes (3-aminopropyl) triethoxysilane (APTES) to create molecular binding chemistry. This has allowed interaction between heavy metals being measured and the sensor component resulting in increasing the current being measured. Due to its, excellent detection capabilities, this sensor was able to identify different group heavy metal species. The device was further integrated with sub-50 µm for chemical delivery.The study proposed characterization and optimization of silicon nanosensor for specific detection of heavy metal. The sensor was fabricated in-house and conventional photolithography coupled with size reduction via dry etching process in an oxidation furnace. Prior to heavy metal heavy metal detection, the capability to aqueous sample was determined utilizing serial DI water at various. The sensor surface was surface modified with Organofunctional alkoxysilanes (3-aminopropyl) triethoxysilane (APTES) to create molecular binding chemistry. This has allowed interaction between heavy metals being measured and the sensor component resulting in increasing the current being measured. Due to its, excellent detection capabilities, this sensor was able to identify different group heavy metal species. The device was further integrated with sub-50 µm for chemical delivery.

Drug carrier in cancer therapy: A simulation study based on magnetic carrier substances

The principle of magnetic carrier is a medium for transferring information by sending the drug to the specific part to kill tumor cells. Generally, there are seven stages of cancer. Most of the patient with cancer can only be detected when reaches stage four. At that stage, the cancer is difficult to destroy or to cure. Comparing to the nearly stage, there are probability to destroy tumor cell completely by sending the drug through magnetic carrier directly to nerve. Another way to destroyed tumor completely is by using Deoxyribonucleic acid (DNA). This project is about the simulation study based on magnetic carrier substances. The COMSOL multiphysic software is used in this project. The simulation model represents a permanent magnet, blood vessel, surrounding tissues and air in 2D. Based on result obtained, the graph shown during sending the magnetic flux is high. However, as its carry information the magnetic flux reducess from the above, the move from 0m until 0.009 m it become the lowers and start increase the flux from this until maximum at 0.018m. This is due the fact that carrier start to increase after because the low information is gradually reduce until 0.018m.The principle of magnetic carrier is a medium for transferring information by sending the drug to the specific part to kill tumor cells. Generally, there are seven stages of cancer. Most of the patient with cancer can only be detected when reaches stage four. At that stage, the cancer is difficult to destroy or to cure. Comparing to the nearly stage, there are probability to destroy tumor cell completely by sending the drug through magnetic carrier directly to nerve. Another way to destroyed tumor completely is by using Deoxyribonucleic acid (DNA). This project is about the simulation study based on magnetic carrier substances. The COMSOL multiphysic software is used in this project. The simulation model represents a permanent magnet, blood vessel, surrounding tissues and air in 2D. Based on result obtained, the graph shown during sending the magnetic flux is high. However, as its carry information the magnetic flux reducess from the above, the move from 0m until 0.009 m it become the lowers and start inc...

Specific and selective target detection of supra-genome 21 Mers Salmonella via silicon nanowires biosensor

The nano structure based on silicon can be surface modified to be used as label-free biosensors that allow real-time measurements. The silicon nanowire surface was functionalized using 3-aminopropyltrimethoxysilane (APTES), which functions as a facilitator to immobilize biomolecules on the silicon nanowire surface. The process is simple, economical; this will pave the way for point-of-care applications. However, the surface modification and subsequent detection mechanism still not clear. Thus, study proposed step by step process of silicon nano surface modification and its possible in specific and selective target detection of Supra-genome 21 Mers Salmonella. The device captured the molecule with precisely; the approach took the advantages of strong binding chemistry created between APTES and biomolecule. The results indicated how modifications of the nanowires provide sensing capability with strong surface chemistries that can lead to specific and selective target detection.