Visible and angular interrogation of Kretschmann-based SPR using hybrid Au-ZnO optical sensor for hyperuricemia detection

Uric acid is a waste product of the human body where high levels of it or hyperuricemia can lead to gout, kidney disease and other health issues. In this paper, Finite Difference Time Doman (FDTD) simulation method was used to develop a plasmonic optical sensor to detect uric acid with molarity ranging from 0 to 3.0 mM. A hybrid layer of gold-zinc oxide (Au-ZnO) was used in this Kretschmann-based Surface Plasmon Resonance (K-SPR) technique with angular interrogation at 670 nm and 785 nm visible optical wavelengths. The purpose of this study is to observe the ability of the hybrid material as a sensing performance enhancer for differentiating between healthy and unhealthy uric acid levels based on the refractive index values from previous study. Upon exposure to 670 nm wavelength, the average sensitivity of this sensor was found to be 0.028°/mM with a linearity of 98.67 % and Q-factor value of 0.0053 mM - 1 . While at 785 nm, the average sensitivity is equal to 0.0193°/mM with slightly lower linearity at 94.46 % and Q-factor value of 0.0076 mM - 1 . The results have proven the ability of hybrid material Au-ZnO as a sensing performance enhancer for detecting uric acid when compared with bare Au and can be further explored in experimental work.

SPR sensor for detection of heavy metal ions: Manipulating the EM waves polarization modes

Water contamination by heavy metals is a common issue encountered in many countries due to industrial and urban wastes in water resources which give health and socio-economic impacts. This work is carried out to investigate the effect of EM wave polarization modes on the sensing properties of surface plasmon resonance (SPR) sensor in detecting heavy metal ions namely mercury (Hg) and plumbum (Pb). Three types of polarization modes such as p-polarized, s-polarized and circular-polarized light were introduced. Gold and silver thin films with thicknesses of 50nm were deposited on top of SPR layer system to excite surface plasmon polaritons (SPPs). The SPR curves were analyzed by studying the FWHM, Q-factor and angle shifting characteristics. We manage to prove theoretically that the SPR phenomena able to be created by using not only the p-polarized light, yet by employing a circular-polarized light. The sensor shows positive respond for both polarization modes, where the troughs were red-shifted about 23.78% as Pb was introduced on the top of the gold-coated SPR sensor.  The SPR angles were shifted about 24.45% as the sensor was exposed with Hg metal ions. Different response due to the presence of different analytes exhibits an excellent criteria of high selectivity sensor.  In conclusion, the combination of p-polarized light or circular-polarized light and gold thin film able to accentuate the significant role of SPR sensor in detecting heavy metal ions.

Increasing Muslim contribution to medical research; reviving a lost legacy

DOI: 10.3329/bjms.v9i2.5653Bangladesh Journal of Medical Science Vol.09 No.2 Apr 2010 pp64-67

The cardiovascular epidemic with particular emphasis on the Muslim world

DOI: http://dx.doi.org/10.3329/bjms.v10i2.7800 Bangladesh Journal of Medical Science Vol.10 No.2 Apr’11 pp.65-71