Formaldehyde, one of the simplest reactive carbonyl substances, is involved in many physiological and pathological processes in living organisms. There is a large amount of data showing that abnormal elevation of formaldehyde is associated with a variety of diseases in the body, such as neurodegenerative diseases, Alzheimer\'s disease, cardiovascular diseases and cancer, and is also a representative carcinogen, so monitoring formaldehyde is of great importance for disease diagnosis and treatment. In this review, In this paper, we summarize and classify the last ten years of probes for the detection of formaldehyde according to different reaction mechanisms and discuss the structures and applications of the probes. Finally, we briefly describe the challenges and possible solutions in this field. We believe that more new probes provide powerful tools to study the function of formaldehyde in living systems.

The present study presents a novel near-infrared optical probe for the sentinel lymph node (SLN) detection in breast cancer patients, based on the recording of scattered photons. The aim of this study was to improve the detection of patent blue V (PBV), a dye routinely injected during clinical practice. A combined injection of the dye and radioactive colloid was used in the 24 patients enrolled in the study. The clinical results of the ex vivo detection of 70 dye-marked SLNs are reported, subsequent to the injection of various quantities of PBV (0.25-2 ml). The accuracy and success rate of an isotopic probe for the detection of radioactive colloid tracer, the eye visibility threshold of the surgeon and the use of a new optical probe were examined. The radio-labeled and dye-marked sentinel lymph nodes were all detected by the radio-isotopic probe, as opposed to the 75% detected by the eye visibility threshold of the surgeon. The optical probe detected all of the nodes, regardless of the volume of the dye injected. The relative PBV concentration computed by the probe facing SLNs with infravisible/visually undetectable dye-mark was relatively constant at 5.5±1.4 μmol/l. The optical detection of the sentinel lymph nodes using PBV and the probe presented in this study have the potential to reduce the false negative detection rate. This instrument is likely to provide surgeons with a simple diagnostic tool, without significantly changing their surgical procedures.