Study on the properties of gold nanoparticles as plasmonic sensing material for chlorothalonil detection

Chlorothalonil-based fungicide has been employed extensively to prevent various fungal diseases in plants to increase yield of crops. Conversely, over-usage of chlorothalonil can have adverse effects to human health and environment. An optical sensor implemented Localized Surface Plasmon Resonance (LSPR) phenomenon offers direct and simple detection method has been developed for chlorothalonil detection. In this study, a simple technique of seed-mediated growth method (SMGM) has been successfully performed to grow gold nanoparticles (GNPs) onto solid substrates. The process parameters; seeding time, growth time and effect of capping agent’s molecular weight were investigated to monitor the effect on nanoparticles formation. It was found that increasing the seeding time affect the surface density of GNPs. Furthermore, the investigation on growth time shows significant impact to the shape and size of nanoparticles with 2 hours growth time formed small particles whiles 5 hours and more produces bigger particles. Moreover, in this work, molecular weight (MW) of polyvinylpyrrolidone (PVP) as shape controlling agent was also investigated to observe the uniformity of nanoparticles. PVP 55,000 produced more uniform shape and size of gold nanoparticles compared to PVP 40,000. The prepared sample with 3 hours seeding time, 8 hours growth time and 55k MW of PVP produced highest surface density of GNPs which is 53.66 ± 1.23 %. This sample was further used as a sensing material in detection of chlorothalonil. The sensitivity of the sensor system is determined by measuring the change of peak position and intensity on t-SPR and l�SPR band of GNPs in three mediums; air, deionized water and chlorothalonil solution. Chlorothalonil with 30 mM concentration (without GNPs) exhibits no significant peak and thus proven that GNPs is more suitable to be used as sensing material. Besides, GNPs shows good stability response in 600 seconds with fast response and recovery time during five cycles change of medium. As a conclusion, the GNPs was successfully synthesised and used as sensing material for chlorothalonil detection from 1mM to 40 mM

Formation of Monolayer Polystyrene Array Template for Gold Nanomesh Structure

In this study, the preparation of monolayer array template was performed using 0.2 µm polystyrene (PS) nanospheres monodisperse micro particle deposited onto Indium Tin Oxide (ITO) coated glass substrate. The template was used to arrange the gold (Au) in nanomesh structure thus, enhance its homogeneity for having better sensitivity and repeatability in the plasmonic sensor application. PS nanosphere template was prepared by diluting 0.2 µm PS liquid with ethanol in the ratio of 1:3 and stirred with 400 rpm for 1 hours at 40 °C. Next, the PS solution was spin coated on ITO substrate at different speed variation starting from 200 rpm to 800 rpm in 3 minutes at room temperature. The template structure was then inspected with Field Emission-Scanning Electron Microscopy (FESEM). It was found that, the PS nanosphere template with 600 rpm speed shows the most orderly arrangement of PS array. Subsequently, the PS array template was used as a mask to deposit gold (Au) and performed via direct current (DC) sputtering method. Finally, the Au nanomesh structure was obtained using the lift ‒ off process of PS nanosphere template

Synthesis of Gold Nanorices on ITO Substrate Using Silver Seed-Mediated Growth Method

Herein, we propose a seed-mediated growth method for synthesis of gold nanorices directly grown on the substrate using silver seed. The as prepared sample was characterized using UV-Vis spectrometer, field emission scanning electron microscopy (FESEM), and X-Ray diffraction (XRD). The UV-Vis spectrum of the sample shows transversal surface plasmon resonance (t-SPR) peak at wavelength 541 nm and longitudinal surface plasmon resonance (l-SPR) peak at wavelength 730 nm. The FESEM image confirmed the morphology of gold nanostructures are rice-like shape. Typically, the nanorices have long axis (a) 55.54±3.30 nm, short axis (b) 28.71±2.30 nm, and aspect ratio (a/b) 1.98±0.09. The XRD pattern of the sample at diffraction angle (2θ) in the range of 10º-70º reveals three peaks at 38.18º, 44.48º, and 64.67º which corresponding to (111), (200), and (220) Bragg’s reflection of face centers cubic lattice Gold (ICSD file No. 98-005-3763). The strong peak intensity at 38.18º represents the nanorices growth in the (111) direction. The gold nanostructures with rice-like shape which exhibit two localized surface plasmon resonance (LSPR) thus it has very potential for application in plasmonic sensin

Mini Review of Glucose Detection Using Plasmonic Sensor

Glucose is a crucial compound in human life. Glucose has important roles in energy source production and overall brain health. In addition, it can be converted into other compounds essential for the growth, repair, and maintaining tissues throughout the body. Also, glucose becomes an indicator of diabetes, i.e., ill when the body can not produce insulin hormone properly. The poor management of diabetes can affect long-term complications that can significantly impact a person's quality of life and may lead to disability or even premature death if not properly addressed. Thus, it is important to do glucose detection to stay within a healthy range. The common methods patients use are glucose meters and urine testing on the laboratory scale. This method has several areas for improvement, such as being invasive, needing experts, and requiring a long-time detection. Thus, researchers come into various alternative glucose detection such as chromatography, mass spectrometry, electrochemical, and plasmonic sensor. Chromatography for glucose detection is rarely used in recent years because of its complexity. Then, for mass spectrometry, it is also complicated for the result and maintenance. As for electrochemical methods, the disadvantage is that other electroactive components on the sample can be interfered with. Plasmonic sensors that utilize the Localized Surface Plasmon Resonance (LSPR) phenomenon are considered due to their advantage, i.e., non-invasive, real-time monitoring, and highly sensitive to surrounding medium change. Plasmonic sensors usually use components of light absorption, luminescence, fluorescence, Raman scattering, reflectance, and refractive index based on the nanoparticles used as sensing materials. Still, transmission and reflection are popular and widely applied. Furthermore, plasmonic sensors generally consist of instruments such as a light source, fiber optic, chamber to place substrate/analyte, spectrometer/detector, and computer. Besides, plasmonic sensors can produce different analytical characteristics suitable for different cases and tuned for the need because of the various sensing materials used. Hence, plasmonic sensors become a promising alternative method for glucose detection

A study on the rights of children born out of wedlock to inherit property from their 'parents'/ Aaina Liyana Abd Manaf…[et al.]

This thesis deals with the law of inheritance in Malaysia. It concerns the rights of illegitimate children to inherit property from their 'parents'. The main objective of this research is to make a fair comparison between the two different laws, i.e. Islamic law and also civil law and to lay down the rights of inheritance of the illegitimate children. Basically, the general rule in both laws is that only legitimate persons are entitled to inherit. Our first impression regarding the title of our research was that illegitimate children are generally prohibited to get inheritance. However, after studying the laws critically and carefully, we found out that illegitimate children do indeed have rights to inheritance. Legitimacy is the key to inheritance. Therefore, we believe that we ought to discuss into detail of the law of legitimacy and how one's status can be illegitimate. For Muslims, the law that governs them is the divine words of Allah in the Holy Quran. Islam has set out strict rules regarding the rules of inheritance. With such rigidity, it is impossible to alter the position of illegitimate children under inheritance. However, an illegitimate child is considered as the child of his mother and thus, his rights to inheritance lie with the mother. For non-Muslims, the laws available are the Distribution Act 1958, Inheritance Act 1971 and Wills Act 1959. There is no provision under the civil law specifically stating that an illegitimate child cannot inherit from his or her 'parents' but the law provides an alternative for these illegitimate children to inherit and that is, by way of legitimization. The process of legitimization makes the illegitimate child to be legitimate and therefore, makes the child as the lawful child of his 'parents' or adopted parents

Video Attributes in Teaching and Learning: A Systematic Review

This study was conducted to establish guidelines for video attributes for electrical subjects. Based on previous research, researchers have found several elements that must be present in the process of preparing video attributes. Data analysis conducted by the researchers found a total of 12 related papers from 32 sources of search. The results of the observations carried out by the researchers found that the elements that need to be in the preparation of the video are text, animation, movement, segmentation, and some related ones, as stated in the finding section

Development of Auto Roll Prayer Mat for Musolla

During Friday or ‘Hari Raya’ festival, mosques will be flooded with Muslims who wish to perform prayers. Normally, mosques or ‘musolla’ require a large prayer space and certainly committees of the mosques would like to provide a comfortable space to perform prayer. However, the problem comes when the area provided is small and therefore the mosque’s person in charge which is known as ‘tok siak’ needs to prepare additional prayer mat for them. In this study, Auto Roll Prayer Mat (ARPM) is a new innovation idea system that was designed to ease the burden and at the same time to make the task more efficient. ARPM can perform in two conditions, which are it can stretched out prayer mat automatically and the other is that the prayer mat also can roll back to its actual condition. The overall system was supported with a main component of the system which was a power window motor accompanied with pulse width modulation (PWM) motor controller circuit. Moreover, ARPM was also equipped with secondary function of an automatic cleaning process where the ARPM system was able to clean the prayer mat by using a servo motor and Arduino UNO microcontroller, while simultaneously stretching out the prayer mat

Laser Technology Applications in Critical Sectors: Military and Medical

This study aims to observe laser technology applications in two critical sectors which are military and medical. These two crucial sectors required a technology that compatible with the nature of the field; safe, precise and fast (time –saving). A laser is defined as a device that emits a focused beam of light by stimulating the emission of electromagnetic radiation. The characteristics of lasers; coherence, directionality, monochromatic and high intensity are very suitable to be used in the critical sectors. In the military sector, the implementation of laser is commonly used in various types of weapons manufacturing. In this paper, three different military weapon systems namely weapon simulator, laser anti-missile system and navy ship laser weapon system were studied. Meanwhile, in the medical sector, the laser is widely implementing in medical equipment especially in dentistry, surgery and skin treatment. The capability of laser technology to be adapted in the critical sectors can be further investigated and enhanced for future discovery

Effects of growth solutions ageing time to the formation of gold nanorods via two-step approach for plasmonic applications

We demonstrate the structural reorganization of gold nanorods (GNRs) that could fine-tune localized surface plasmon resonance (LSPR) by using modified wet chemical synthesis on the solid substrate. Controlling the growth solution ageing time using the modifiable GNRs is an approach to overcome the limitations of rods formation due to inhomogeneous and uncontrollable size and aspect ratio. In this study, the suitable ageing time of GNRs was determined to produce optimum GNRs in terms of surface density and aspect ratio. As the ageing time was increased from 30 min to 24 h, the colour of the growth solution was changed from light to dark purple. The change is associated with the density of the nanorods formation. The optical spectral peaks of GNRs occur in a range between 500 nm and 800 nm in the visible and near-infrared region spectrum for transverse surface resonance (t-SPR) and longitudinal surface resonance (l-SPR), respectively. From the morphological analysis, it was found that 20 h ageing time resulting in high density and homogeneous GNRs with 74.81% surface density with 4.23 ± 0.04 aspect ratio. Hence, the growth ageing time of GNRs can be manipulated to control their shape evolution and dimension in terms of size and aspect ratio. The controllable aspect ratio and size GNRs can be potentially used as sensing material in plasmonic applications