Surface plasmon resonance (SPR) sensors are known to be able to detect very low surface concentrations of (bio)molecules on macroscopic areas. To explore the potential of SPR biosensors to achieve single-molecule detection, researchers have been investigating various methods to enhance the sensitivity of these sensors. One approach is to use nanoparticles functionalized with specific biological recognition molecules to amplify the sensor response. This method has shown promising results in detecting low concentrations of biomolecules. However, there are still challenges to overcome before achieving single-molecule detection with SPR sensors. Further research is needed to improve the sensitivity and specificity of these sensors, as well as to develop new methods for detecting single molecules.