and other chemicals were supplied from Sigma Aldrich. HRP conjugated-melamine antibody (HRP-ab) was from Beacon. Pt wire (dia. 0.2 mm) and Ag wire (dia. 0.5 mm) were from Nilaco (Japan). Silicon wafer was from Mitsubishi Metal Corp. and glass-fiber filters were fromMerck. Liquid blocker super pap pen mini and plastic backingwere supplied by Daido Sangyo, Japan. Pure water used was double distilled with maximum conductivity of 18 MΩ obtained from Simply-Lab
water system (DIRECT-Q 3 UV, Millipore).