Fast growing used of QCM biosensor has been reported. It is well known that the QCM sensor responses both to mass or viscosity changes. In its operation as mass sensitive sensor, a QCM responses to the mass change per surface area. In the use of QCM biosensor, immobilization of the bio sensitive layer on top of the sensor surface is one of the importance factors. The immobilization of the biomolecule can be done directly on top of the sensor electrode or by using a coating material as supporting matrix. This experiment shows that the use of thick polystyrene coating with a rough surface resulted from air brush technique resulted in a significant improvement on the biomolecule immobilization compare to the polystyrene coating using spin coating method. As there is no chemical or physical modification on the polystyrene coating, the increasing numbers of the immobilized biomolecule merely a result of the surface geometry. The increasing number of immobilized biomolecule is caused by improving total surface area per perpendicular surface area of the sensor by introducing surface roughness. However, an appropriate care must be taken during the coating process to avoid over rough surface which in turn can heavily damp the QCM sensor.
This research aimed to prove the existing natural transition of Metal Coordination Anthocyanin complex (MAC) from the freeze-dried of Java plum (Syzygium cumini) fruit and its role as free radical scavenging. The Liquid Chromatography-Mass Spectrometry (LCMS) analysis showed the presence of anthocyanin in the fruit, while transition metals of Fe, Cu, and Ni were also found as detected by X-Ray Fluorescence (XRF). The Fourier Transform Infrared Spectroscopy (FTIR) spectra revealed the interaction of organic functional groups with transition metals. These facts were supported by X-Ray Powder Diffraction (XRD) and polarizing microscope images which displayed both amorphous and crystallite microstructures related to organic and bioinorganic content in the fruit. The analysis of complex compound indicated the transition metal as coordinator atom and a cyanidin acts as a chelator among anthocyanins existing in the fruit. The paramagnetic property of MAC in the fruit as a free radical scavenger was demonstrated by the reduction of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical intensity in the Electron Spin Resonance (ESR) spectrum. These findings suggested that S.cumini fruit contains naturally existing MAC.
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