Book excerpt: This book provides a comprehensive overview of the use of noble metal nanoparticles for bioimaging and biosensing. It starts with a review on the synthesis, characterization, optical properties, and bioconjugation of noble metal nanoparticles, followed by introduction of various biodetection techniques based on noble metal nanoparticles. In between these topics, microfabrication of biosensing chips and the use of microfluidics to enhance biosensing performance are discussed.