Influence of Saline Buffers over the Stability of High-Annealed Gold Nanoparticles Formed on Coverslips for Biological and Chemosensing Applications

Herein, coverslips were used as solid supports for the synthesis of gold nanoparticles (AuNPs) in three steps: (i) detergent cleaning, (ii) evaporation of 4 nm gold film and (iii) exposure at high annealing temperature (550 °C) for 3 h. Such active gold nanostructured supports were investigated for their stability performances in aqueous saline buffers for new assessments of chemical sensing. Two model buffers, namely saline-sodium phosphate-EDTA buffer (SSPE) and phosphate buffer saline (PBS), that are often used in the construction of (bio)sensors, are selected for the optical and microscopic investigations of their influence over the stability of annealed AuNPs on coverslips when using a dropping procedure under dry and wet media working conditions. A study over five weeks monitoring the evolution of the localized surface plasmon resonance (LSPR) chemosensing of 1,2-bis-(4-pyridyl)-ethene (BPE) is discussed. It is concluded that the optimal sensing configuration is based on annealed AuNPs exposed to saline buffers under wet media conditions (overnight at 4 °C) and functionalized with BPE concentrations (10(−3)–10(−11) M) with the highest LSPR spectra after two weeks.