Gold has been a part of people’s lives for ages and is used as money, goods and jewellery. In recent years, gold has played a key role in chemistry, medicine and biology. Since the 1970s, gold has been extensively used as a catalyst in several chemical transformations. Due to its high biocompatibility, functionalized gold nanoparticles have been extensively employed as drug and gene delivery systems, biosensors and bio-imaging materials. However, gold complexes can become toxic to the human body by interacting with biomolecules such as DNA and enzymes. Therefore, detection of trace amounts of gold species is an important issue and can be achieved via spectroscopic methods such as atomic absorption spectroscopy, atomic emission spectroscopy and inductively coupled plasma spectrometry. However, these analytical methods require complicated sample preparation steps and sophisticated instrumentation. In contrast to these extremely expensive and time-consuming methods, fluorogenic or chromogenic methods, which provide high analyte sensitivity and selectivity, can serve as good alternatives for detecting gold species. To develop new probes for the detection of Au3+ ions, we focused on the design of new fluorescein-based probes that are soluble in aqueous media. We aimed to investigate the in vivo activity of these fluorescent probes. In the proposed detection system, gold ions are expected to mediate a chemical reaction through coordination to an alkyne moiety that results in a ring opening reaction to yield a highly fluorescent derivative.