A cost effective strategy for dual channel optical sensing of adrenaline based on 'in situ' formation of copper nanoparticles

Assessment of adrenaline (ADR) levels in biological fluids and pharmaceutical formulations is of prime importance due to its association with many disease conditions. Here a novel, cost effective, dual channel sensing strategy is developed for ADR based on in situ formation of copper nanoparticles. The proposed sensor works via both fluorimetry and colorimetry. Visual detection was also enabled by color change of solution from pale blue to reddish brown. Here CuCl₂ solution is used as probe to simplify method and was function as excellent fluorimetric as well as colorimetric ADR sensor. Fabricated sensor is very simple, selective and reproducible in nature. Proposed sensor works fluorimetrically in linear range of 3.00 × 10^-5 to 5.00 × 10^-7 M and colorimetrically in linear range of 5.00 × 10^-4 to 2.00 × 10^-5 M. Artificial urine and commercial pharmaceutical formulations were successfully analyzed as samples for estimation of ADR by developed dual channel sensor.

Multi-coloration of Calixarene-coated Silver Nanoparticles for the Visual Discrimination of Metal Elements

Upon mixing with metal ions such as Cd^II, Tb^III, Cu^II, Ni^II, Pb^II, Zn^II, and Co^II at pH 10.0, solutions of silver nanoparticles (AgNPs) coated with calix[4]arene-p-tetrasulfonate (CAS-AgNP) exhibited multi-coloration from yellow to orange, violet, and green, depending on the metal elements present, which allowed for visual discrimination of the ions. This is contrary to the AgNP sensors exhibiting a uniform color change from yellow to red upon binding of a receptor molecules at the surface of AgNPs to an analyte. The TEM images of the samples obtained from the resultant solution showed two regions. First, a region where CAS-AgNPs assembled on the surface of the metal hydroxides. The size of the hydroxide crystals varied from 50 to 200 nm with the type of metal element present, and roughly correlated with the extinction band of the aggregated AgNPs. Second, the amorphous region in which CAS-AgNPs dispersed randomly. The difference in the amount of the crystal region and the area seemed to lead to the multi-coloration.