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Title:	New electrochemical biosensors and optical sensors for carrageenan analysis
Authors:	Riyadh Abdulmalek Ali Hassan (P51332)
Supervisor:	Lee Yook Heng, Prof.
Keywords:	Electrochemical biosensors Optical sensors Carrageenan Food prepareation Detectors
Issue Date:	6-Oct-2016
Description:	Carrageenan is used in food preparation and its safe daily intake for adults is 75 mg/kg of body mass per day and it is not allowed in infant food formulations. Although carrageenan is presumed to be safe in foods, the use of carrageenan still has health risks. Thus, many approaches for the detection of carrageenan have appeared lately in order to determine its concentration in foods. The analysis of carrageenan using sensing evices is still relatively unexplored and can provide a simpler way of determination when compared with current methods available. Thus, in this thesis, sensors and biosensors were develped based on electrochemical (voltammetry and potentiometry) and optical (fiber optic sensors with reflectance and florescence) methods. For the optical sensors based on reflectance and florescence, modified acrylic polymer microspheres were successfully synthesized for increased sensor performance via emulsion photopolymerization. The material was blended with methylcellulose (MC) to design a film containing methylene blue (MB) as an indicator. The polymer microspheres were prepared from photopolymerisation of a emulsion containing the monomers n-butyl acrylate (nBA) and 1,6- hexanadiodiacrylate (HDDA). The size of the acrylic microspheres ranged from 0.2-5 uM. FT-IR analysis of the microspheres showed that they were successfully modified with MC to produce a film for the immobilizationof MB. The reflection or emission intensity change was found to be proportional to the carrageenan concentration in the linear range of 100-1000 and 1-20 ppm (R 2=0.9923) with lower of detection limit 80 and 0.4 ppm respectively. The two new biosensors for carrageenan were based on DNA was immobilised onto the carbon screen-printed electrodes (C-SPE) without any potential applied followed by MB accumulation. The biosensor response was generated by the MB labels during competitive interaction with carrageenan and was measured via differential pulsed voltammetry (DPV). This biosensor yielded a linear response range of 1-10 ppm (R 1=0.982) of carrageenan with a limit of detection of 0.008 ppm. A new potentiometric biosensor ofr carrageenan was constructed based on the hydrolysis of x-carrageenan by Pseudomonas carrageenovora, which was monitored via immobilizing these marine bacteria cells on a Ag/AgCl screen-printed electrodes (AgC1-SPE) containing an scrylic membrane with a H 1 selective ionophore acting as a proton transducer for pH change during the hydrolysis reaction. The k-carrageenan from 0.2-100 ppm in 20 mM buffer at pH 7.5 and sensitivity was 58.78=0.87 mV/decade (R 2 =0.995) with a lower limit of detection of 0.05 ppm. This biosensor shoed excellent selectivity towards k-carrageenan compared with other carrageenans that were tested (e.g. 1-carrageenan and x-carrageenan). In conclusion, new carrageenan sensors and biosensors have been successfully designed and found to be suitable to be used in the analysis of real sample containing carrageenan.,Certification of Master's/Doctoral Thesis" is not available
Pages:	186
Call Number:	TK7871.674.H337 2016 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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