Tuesday, 31 May 2022: 08:00
West Meeting Room 205 (Vancouver Convention Center)
Imaging in the near infrared (NIR) range of the spectrum is beneficial due to reduced light scattering, absorption, toxicity and autofluorescence. However, there are only few near infrared fluorescent materials known and suitable for biomedical applications. Here, we exfoliate the near infrared fluorescent layered pigment CaCuSi4O10 (known as Egyptian Blue, EB) via different mechanical and chemical approaches into nanosheets (EB-NS) of high monodispersity. Dimensions of the nanosheets decrease with sonication time < 10 nm down to single EB layers (around 1 nm). The near infrared fluorescence of EB at 910 nm is retained in EB-NS and the total fluorescence intensity scales with size. Furthermore, we demonstrate that EB-NS display ultra-high photostability (no bleaching), are extremely bright compared to other NIR fluorophores and can be used for lifetime encoded imaging. We also show that the fluorescence lifetimes in the µs range depend on particle size and can be used to enhance contrast in imaging. In summary, we introduce exfoliated 2D CaCuSi4O10 nanosheets as versatile NIR material for biophotonics.