Research and application discussion on new technology for detecting cadmium ions based on a near-red light carbon dot fluorescence quenching method

Cadmium ions are considered one of the most dangerous heavy metal pollutants. The human body does not require cadmium for growth and development, yet continuous intake of cadmium ions due to environmental pollution can lead to their accumulation in the body. This accumulation can result in damage to the urinary system and, in severe cases, pose life-threatening risks. The current conventional methods for analyzing heavy metals in the environment primarily include inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS), and inductively coupled plasma atomic emission spectrometry (ICP-AES). These methods are known for their drawbacks such as complex testing procedures, as well as expensive instrumentation and equipment. In this study, a novel technique for detecting cadmium ions using the near-red light carbon spot fluorescence burst method was developed. The near-infrared carbon dots (NIR-CDs) exhibited vibrant deep red fluorescence ranging from 625 to 710 nm, with a prominent peak at 685 nm. At a pH of 7 and a concentration of 0.1805 g L^-1, the linear detection range for Cd²⁺ was determined to be 0.15-0.75 μM. The CDs demonstrated selectivity for Cd²⁺ detection, boasting an impressive detection limit of 0.397 nM. Mechanistic studies indicated that the interaction between red carbon dots and cadmium ions involved dynamic bursting of the ions. The practical application of the near-red light carbon spot fluorescence burst method for detecting cadmium ions could be further explored through the establishment of a Cd²⁺ recovery detection system.