Binding indocyanine green to human serum albumin potentially enhances the detection of sentinel lymph nodes. An initial step for facilitating the detection of first-station nodes in penile and other urological cancers.

Introduction: Surgical oncology strives to remove the primary cancer tumor together with its local lymphatic tissue. One of the techniques improving the staging of lymph nodes is sentinel node biopsy. The most common agent used in SNB is indocyanine green (ICG). Indocyanine green is characterized by its high affinity for human serum albumin (HSA). In practice, the visualization of the sentinel node is enhanced by attaching a relatively large carrier to the ICG molecule. The aim of this study was to investigate whether the covalent linking of ICG to a nanocolloid would extend the time of detection of the dye as it binds to HSA, assessed by fluorescence measurements in vitro. Material and methods: The influence of the molar concentration of ICG on its ability to form a complex with HSA was investigated. The dye luminescence was measured, with an increasing amount of dye in the presence of a constant concentration of HSA. The stability of the ICG:HSA complex was also investigated. Results: The binding of ICG and human protein in a solution ratio of 3 : 1 made it possible to detect the ICG luminescence with better and prolonged visibility. In the case of the two lowest ratios, complex formation was not observed. The use of ICG bound to a nanocolloid based on human serum albumin increases the luminescence of the HSA : ICG complex up to 98%. Conclusions: Properly selected proportions of human albumin protein and ICH allowed higher and longer luminescence to be achieved. Nevertheless, further studies are necessary to establish the optimal concentration ratio.