Colloidal Nanoparticles for Signal Enhancement in Optical Diagnostic Assays

The use of nanotechnologies for the development of highly sensitive and affordable diagnostic assays has significantly improved the ability to detect and characterize multiple types of biomarkers. Semiconductor and metal nanoparticles with unique optical properties have been successfully integrated within biomarker detection schemes for the generation and enhancement of optical signals in label-based and label-free assays. Highly sensitive label-based diagnostics has been realized particularly via using quantum dots (QDs) as labeling probes. Similarly, many label-free techniques that are emerging as potential complements to label-based approaches benefit from signal enhancement strategies using e.g., metal nanoparticles. This review presents a concise overview of recent advances in diagnostic assays that utilize nanoparticles for the generation and enhancement of optical signals in fluorescence- and surface plasmon resonance-based techniques. Advanced diagnostic assays that utilize nanoparticles provide major improvements in detection sensitivity, which can potentially meet the challenging requirements of clinical diagnostics.