Microplasma-Assisted Synthesis of Colloidal Gold Nanoparticles and Their Use in the Detection of Cardiac Troponin I (cTn-I)

We used an atmospheric-pressure non-thermal microplasma for the synthesis of aqueous gold nanoparticles (AuNPs). The microplasma-induced liquid chemistry was analyzed by monitoring the pH value and the conductivity of the liquid. Morphology and optical properties of the synthesized AuNPs were characterized by transmission electron microscopy (TEM) and ultraviolet-visible (UV-VIS) spectroscopy. We found that the size distribution of AuNPs can be tailored by altering the process parameters (stirringmode, discharge power, and concentration of sodium citrate in the liquid). The synthesized AuNPs were used to detect cardiac troponin I (cTn-I) based on lateral flow immune-chromatography assays (LFIA). Test strips prepared by microplasma-generated AuNPs showed an increased sensitivity compared to strips prepared by AuNPs produced by conventional chemical reduction. This might be attributed to an increased negative charge density on the surfaces of the microplasma-generatedAuNPs.