Near infrared quantum dots for biosensing and bioimaging

Quantum dots (QDs) possess unique optoelectronic properties, which make them very attractive to be used as optical probes in biosensing and bioimaging applications. The strong absorbance and light scattering of biological compounds like tissue and blood in the visible range pose a problem. However, if optical probes emitting in the near-infrared (NIR) range are used, scattering, absorption, and autofluorescence of biological components are strongly reduced. This allows for an increased light penetration depth and higher spatial and temporal resolution for the investigation of biological processes. The synthesis and application of NIR emitting QDs is a fast-growing research field and the benefits of using QDs were demonstrated for a variety of applications, such as photoelectrochemical biosensor, in vivo vascular imaging, and fluorescence-guided surgery. This article reviews the state-of-the-art developments in the preparation of NIR/IR QDs and highlights the latest research about their utilization in biosensing and bioimaging applications. • Summary of recent NIR QD preparation methods their applications in biosensing and bioimaging. • New synthesis strategies for NIR QDs result in high PL quantum yields and tuneable PL emission bands in the entire NIR range. • NIR QDs as photoelectrochemical biosensors showing high sensitivities towards target biomolecules. • NIR range highly beneficial for in vivo imaging applications, due to much lower scattering and autofluorescence of biological tissue. • Silver chalcogenides enable high spatial resolution images of vascular structures.