Tijjani Adam

Highly sensitive silicon nanowire biosensor with novel liquid gate control for detection of specific single-stranded DNA molecules

The study demonstrates the development of a liquid-based gate-control silicon nanowire biosensor for detection of specific single-stranded DNA (ssDNA) molecules. The sensor was fabricated using conventional photolithography coupled with an inductively coupled plasma dry etching process. Prior to the application of DNA to the device, its linear response to pH was confirmed by serial dilution from pH 2 to pH 14. Then, the sensor surface was silanized and directly aminated with (3-aminopropyl) triethoxysilane to create a molecular binding chemistry for biofunctionalization. The resulting Si‒O‒Si‒ components were functionalized with receptor ssDNA, which interacted with the targeted ssDNA to create a field across the silicon nanowire and increase the current. The sensor shows selectivity for the target ssDNA in a linear range from target ssDNA concentrations of 100 pM to 25 nM. With its excellent detection capabilities, this sensor platform is promising for detection of specific biomarkers and other targeted proteins.

Nanobiosensor for the detection and quantification of pork adulteration in meatball formulation

A 27-nucleotide AluI fragment of swine cytochrome b (cytb) gene was integrated to 3-nm diameter citrate–tannate-coated gold nanoparticles to fabricate a species-specific nanobiosensor. The biosensor was applied to authenticate pork adulteration in meatball formulation, which is a favourite food in many Asian and European countries. The sensor was found to be sensitive enough to detect 1% pork in raw and cooked meatballs, prepared from the previously mixed pork and beef in specific ratios (% w/w). The hybridisation kinetics of the hybrid biosensor was studied with synthetic targets from moderate to extreme target concentrations and a hyperbolic relationship was found. However, linearity was observed with probe/target ratios 4:1 to 1:2. This part of the curve quantified target DNA in ready-to-eat mixed meatball preparations with more than 90% accuracy. The biosensor probe was hybridised with a target DNA that was several-fold shorter than a typical PCR-template. This offered the detection and quantitation of potential targets in highly processed meat products or extensively degraded samples where PCR-based identification technique might not work due to the fragmentation of comparatively longer DNA. We believe that the assay can be used as an alternative to qPCR for determining shorter size DNA sequences in degraded samples to address a range of biological problems, such as food analysis, bio-diagnostics, environmental monitoring, genetic screening and forensic investigations.

Fabrication and Characterization of IDE Based Sensor through Conventional Lithography Method

This paper mainly illustrate regarding the fabrication process of IDE based sensor for bio-molecular detection process. Material that is utilized in this process is zinc oxide due to bio-compability and elevated electrical characteristic. IDE mask is designed by using auto-cad software which tailors for detection of bio substance which is extremely small scale in size. Zinc Oxide material is also used due to presented of nanostructure that can be synthesized through hydrothermal route. Zinc oxide solution is prepared by series of sol-gel process and is coated on the SiO substrate which acts as insulator layer during the lithography process. IDE mask is patterned transfer on sample by using conventional lithography process which the parameters are critically adjusted to ensure that the pattern transfer process occur with minimal defects. The fabricated sensor will be further validated through electrical and morphological characteristic. Capacitance test and impedance test is taken with various pH solution to observe the response of the sensor with different pH values. Keywords: IDE sensor, bio-compability, Zinc Oxide, auto-cad software, sol-gel, SiO substrate, hydrothermal route

Fabrication of Nanowire Using Ash Trimming Technique

The paper present a report on fabrication of Nanowire using plasma oxidation, we monitor changes by studying the morphology and Δw / Δh, the study also revealed that the proposed fabrication method could potentially be used to fabricate specific nanometer-scale structure and space structure with uniform surface morphology without any damage to the photoresist. Yet with reduced ashing time and without popping of the photoresist ashing process when the a fabricated is being carried out and subsequently trimmed to nanosize by plasma oxidation, the study also revealed the dramatic increase in aspect ratio as the structure reduces in lateral dimension.

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.

Studying Effect Dimensions of Design and Simulation Silicon Nanowire Filed Effect Biosensor

We investigated into report a study biosensor based on silicon into an effect on the dimensions of conductance design and simulation nanowire surface with molecular DNA for sensitivity. In the design nanowire of A biosensor with 3 layers starting with polyisilicon nanowire of radius 8 NM surrounded by a 50-nm electrode layer, and the substrate by a 300nm. COMSOL Multiphysics software used to provide interaction with molecules such as DNA and the distribution of the electrostatic potential in the narrower due to the dimensions, surface nanowire charge was computed using Poisson equation with Boltzmann statistics. In the result of the effect geometry was also studied and the different dimension yield different space charge and the surface charge at interactive site were also investigated and the study demonstrate steps wise identification of all critical parameters for (DNA) attachment with surface nanowires.

Reviewed Immunosensor Format Using Nanomaterial for Tungro Virus Detection

Recently, nanomaterial based biosensor application has drawn a lot attention among researchers because of specialty to enhance the sensor signal for increasing the sensitivity for detecting and identification of pathogen, viruses and toxic compound in controlling plant disease outbreak effectively. Rice tungro disease (RTD) causes a major problem in rice production and also will effect in the economic loss in the country. Therefore, early detection system is needed to monitor the disease at the early stage of the infection for preventing the disease outbreak in planting area. Lastly, this paper will discuss the current findings in rapid diagnostics using immunosensors technologies with nanomaterial application in enhancing the sensor signal for increasing the detection sensitivity

Plant Diseases Detection Using Nanowire as Biosensor Transducer

The plant disease such as Cucumber Mosaic Virus (CMV) and Papaya Ring Spot Virus (PRSV) is a most dangerous disease that can decrease productivity and quality of the vegetable and fruit. Besides that, its also can destroy and kill those plant in long term when infected and to tackle this problem at early stages, the nanowire based biosensor application is a most reliable sensor nowadays because of advantages towards detecting biological molecule especially plant diseases.In order to dealing with tiny form of molecules such as virus is very difficult and due to the nanostructure uniqueness such as nanowire, it can be done by undergo formation of nanowire process.Result will be elaborated about how nanowire working environment in order to detecting those virus.

Nitric acid treated multi-walled carbon nanotubes optimized by Taguchi method

Electron transfer rate (ETR) of CNTs can be enhanced by increasing the amounts of COOH groups to their wall and opened tips. With the aim to achieve the highest production amount of COOH, Taguchi robust design has been used for the first time to optimize the surface modification of MWCNTs by nitric acid oxidation. Three main oxidation parameters which are concentration of acid, treatment temperature and treatment time have been selected as the control factors that will be optimized. The amounts of COOH produced are measured by using FTIR spectroscopy through the absorbance intensity. From the analysis, we found that acid concentration and treatment time had the most important influence on the production of COOH. Meanwhile, the treatment temperature will only give intermediate effect. The optimum amount of COOH can be achieved with the treatment by 8.0 M concentration of nitric acid at 120 °C for 2 hour.

Fabrication of Silicon Nanowires by Electron Beam Lithography and Thermal Oxidation Size Reduction Method

A simple method for the fabrication of silicon nanowires using Electron Beam Lithography (EBL) combined with thermal oxidation size reduction method is presented. EBL is used to define the initial silicon nanowires of dimensions approximately 100 nm. Size-reduction method is employed for reaching true nanoscale of dimensions approximately 20 nm. Dry oxidation of silicon is well investigated process for self-limited size-reduction of silicon nanowires. In this paper, successful size reduction of silicon nanowires is presented and surface topography characterizations using Atomic Force Microscopy (AFM) are reported.