Students undertaking courses in the field of sciences and engineering need to learn practical skills and conceptual knowledge, and the experimental classes are the best moment for this. In this paper, we propose a practical experiment to aid nanotechnology learning by synthesizing gold nanoparticles (AuNPs) and their application as a colorimetric sensor of sulfathiazole. AuNPs were prepared using sodium citrate as a reducing and capping agent. The existence of the synthesized AuNPs was detected using the Tyndall effect while their optical properties were investigated by molecular absorption spectrophotometry. The gold nanoparticles exhibit spherical-like shape morphology and an average size of 13.6 nm, determined by transmission electron microscopy. The AuNPs were applied as a colorimetric sensor for the detection of sulfathiazole in mixed water/ethanol solution by simple visual inspection and using molecular absorption spectrophotometry. Due to the simplicity of the experimental steps, this activity is well-suited for a hands-on introduction of nanoparticles synthesis and its application as a molecular sensor. In addition, the experiment encompasses knowledge from different fields being suitable for interdisciplinary classes.

The growing predominance of nanoscience and nanotechnology makes it increasingly important that these topics become an integral part of all scientific education. For this reason, in the present work, an interdisciplinary experiment of nanotechnology is introduced. As silver nanoparticles (AgNPs) are the most applied nanomaterial in consumer products, the current understanding of their stability is needed. Silver nanoparticles were synthesized using chitosan as a capping agent and a size distribution of 9.7 nm was determined by transmission electron microscopy. After preparation, the AgNPs colloid was divided into two parts. One part was stored in dark at 4.0 ± 1.0 ºC and it was removed out from the fridge only to be analyzed by UV-vis. The second part was used to study the colloid stability in the presence of Hg2+, and also in the combination of mercury with the ions Cu2+, Fe2+, Ni2+, Sn2+, and Zn2+. The UV-vis analysis indicated that the AgNPs were oxidized in the presence of these ions, but in different intensities, which can be explained by using the electrochemistry approach. This work may be relevant for graduate-level or upper-level undergraduate experimental course preparation as the procedure is simple and easily reproducible in a typical chemistry laboratory.