Green synthesis of selenium nanoparticles (SeNPs) is produced by mixing Curcuma longa leaves extract and sodium hydrogen selenite (NaHSeO₃) solution. Curcuma longa leaves extract act as reducing, stabilizing and capping agent. Selenium nanoparticles formation was assisted by using microwave-assisted method. This work focusing on determining the electrochemical properties of the selenium nanoparticles (SeNPs) through characterization and application. Formation of SeNPs confirmed using UV-Vis spectrophotometer, morphological and size of the SeNPs through Field Emission Scanning Electron Microscopy (FESEM) presence of functional groups using Fourier-Transform Infrared Spectrophotometer (FTIR), amorphic nature of the SeNPs through X-Ray Diffraction (XRD) where spherical and average size of 251nm were observed. For its electrochemical properties, the 20µL SeNPs was used for modification in electrocatalytic of bare glassy carbon electrode (GCE). The electrooxidation by SeNPs/GCE of nitrite was examined via cyclic voltammetry where increase of oxidation current can be observed approximately at 0.8V.

Intelligent pH indicators have been gain interested in food industry as its acts as intelligent packaging where can be monitored and providing information and warning customer on the food condition in real time pH indicator. Calorimetric pH indicator used as indicator system in the packaging as in the most cases, pH changes can be detected when food deterioration occurs. However, the current pH indicator has lower colour changes and lower stability. In this research, new pH indicator was produced and have pronounced colour changes in wide range of pH that have higher stability to temperature and light from natural colorant sources. Two method of extract’s preparation was conducted to evaluate the effect of anthocyanin contents which is with or without steaming. The characterization was done by observing the physical appearance, total anthocyanin contents, UV-Vis analysis and colour response of anthocyanin to various PH solution. As the results, steaming of sweet potatoes preparation method was found able to produce dark purple colour with high value of total anthocyanin contents. Anthocyanin colour produced using steaming process results more intents colour at pH 1 to pH 13 compared to without steaming. These finding was supported with UV-Vis peak that showing different wavelength which corresponding to the various colour produced. The results obtained show the anthocyanin extracts is a promising component to be used as pH indicator since its stimuli responsive with the pH of the environments.

Plastic packaging is widely used in food industry to protect and maintain food freshness. However, plastic packaging also contributes to solid waste problem and can become the contamination area of microbial activities which in turn affecting the shelf-life of the food product and may causing food-borne illness towards consumer. Thus, the demands on biodegradable polymer as plastic packaging has grown widely especially among the food industry. The employment of silver nanoparticles (AgNPs) can improve physical properties of biopolymer as well as promoting antimicrobial properties on the plastic packaging. The aim of this study is to synthesize of AgNPs by utilising acetylated starch (AS) as reducing agent with different parameters via microwave irradiation method. The effect of different ratio of acetylated starch and microwave time-varying exposure is evaluated. The synthesized silver nanoparticles were characterized via UV-VIS spectroscopy (UV-VIS), X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. The absorbance peak emerges at 420nm on UV-VIS shows that silver nanoparticles is successfully produced. 15 minutes microwave time exposure and 1:1 ratio is identified as the optimum condition to produce silver nanoparticles. The peak emerges on FTIR spectra shows the involvement of starch in reduction process in synthesizing AgNPs. The XRD results shows the amorphous structure of starch and crystalline peak of silver appear in 2Θ regions 37.4°, 43.4°, 63.1° and 75.7°. In conclusion, the significant outcome from the study is the AgNPs were successfully synthesized via microwave irradiation method and be a function of time varying exposure and acetylated starch ratio.

Polyurethane (PU) membranes was prepared using electrospinning followed by modification with 2-hydroxyethyl methacrylate (HEMA) by radiation-induced grafting (RIG) copolymerization method via electron beam. The lack of knowledge of polymer properties of PU-based membrane prepared using RIG method need for dedicated study. Thus, the effect of thermal stability, in vitro degradation, water uptake analysis, and surface morphology after 84 days’ incubation times toward grafted PU-g-poly(HEMA) membrane was evaluated for the first time using thermal gravimetric analysis (TGA), analysis of mass, percentage of water uptake and Scanning Electron Microscope (SEM), respectively. Based on the DTGA curves, the electrospun PU exhibits two-stage of deposition. After grafted with HEMA, the first stage of decomposition was shifted to the lower temperature, and the second stage of decomposition was shifted to a higher temperature. At 500 °C, PU grafted with HEMA leaves residue about 3.526% more elevated in value than original material of PU, which is 1.151%. Degradation test showed that a higher percentage degree of grafting was lowering the percentage of weight loss. SEM images supported the morphology observation shows no noticeable changes such as cracked or eroded has occurred. In conclusion, electrospun PU grafted with HEMA was improved its thermal stability, stable in swelling properties and was found competent to degrade slowly in phosphate buffer saline (PBS). The results show that PU-g-poly(HEMA) exhibits better thermal stability than pure poly(HEMA) and the amorphous regions give the polymer toughness and could be up-and coming candidates for tissue engineering including artificial blood contracting medical devices.

Green synthesis was found to be an environmentally friendly and sustainable approach for producing selenium nanoparticles with good antibacterial properties. Curcuma longa L. commonly known as turmeric is a plentiful plant resource however only the rhizome is in demand by the markets leaving the leaves as waste. Therefore, in this study, Curcuma longa L. leaves extract was used in selenium nanoparticles synthesis from sodium hydrogen selenite, NaHSeO3. The synthesizing process was assisted by microwave heating for 20 minutes at 500 W power. The formation of SeNPs was initially observed from the colour changes of the solution from brownish plant extract to deep orange colour. The surface plasmon resonance of SeNPs was also tested by UV spectra with absorbance at wavelength 265 nm to further confirm the formation of SeNPs. FESEM imaging was also performed to analyse the morphology and the size of the SeNPs with average sizes of 129 and 167 nm. The chemical composition of the SeNPs was also investigated using FTIR to study the functional group responsible for biosynthesized SeNPs. The shifting of O-H at and C=O at shows that these functional groups were involved in SeNPs production. Then the SeNPs were exposed to two different gram pathogens, Staphylococcus aureus and Escherichia coli. The inhibition The SeNPs mediated from C. longa L. extract was found to successfully inhibit the S. Aureus bacteria at 11.01mm. These SeNPs has the potential for applications to combat infection causes by S. aureus.

Dynamic light scattering (DLS) or photon cross-correlation spectroscopy (PCCS) is a very potent means for analyzing the diffusion behaviour of supramolecules in their solution form. The diffusion coefficient, probed from the scattered light by supramolecules underexposure to incident light, allows the hydrodynamic radii to be calculated. However, the scattering values were recently misled by an unexpected interaction between the incident light and thermo-sensitive nanogels. Hence, in turn, it resulted in a miscalculation of the size of the nanogels by more than 100% of their expected values. The study fulfills a vital knowledge gap by investigating the effects of laser intensity on the size of thermo-sensitive Poly(N-Isopropyl Acrylamide-Vinyl Pyrrolidone-Polyethylene Glycol Diacrylate-(2-(Dimethyl Amino)Ethyl Methacrylate)), Poly(NIPAAM-PVP-PEGDA-DMAEMA) nanogels and subsequent count rates in DLS measurements. The Lower Critical Solution Temperature, LCST phase transition of Poly(NIPAAM-PVP-PEGDA-DMAEMA) nanogel can be observed using the DLS technique. The higher laser intensity was advantageous for measuring at high dilution more vigorously with varying laser intensities. Thus, a sufficient laser intensity should be chosen based on the light scattering characteristics of typical samples.