Exfoliated near infrared fluorescent silicate nanosheets for (bio)photonics

Abstract

Imaging of complex (biological) samples in the near-infrared (NIR) is beneficial due to reduced light scattering, absorption, phototoxicity, and autofluorescence. However, there are few NIR fluorescent materials known and suitable for biomedical applications. Here we exfoliate the layered pigment CaCuSi 4 O 10 (Egyptian Blue, EB) via ball milling and facile tip sonication into NIR fluorescent nanosheets (EB-NS). The size of EB-NS can be tailored to diameters <20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the fluorescence intensity correlates with the number of Cu 2+ ions. Furthermore, EB-NS display no bleaching and high brightness compared with other NIR fluorophores. The versatility of EB-NS is demonstrated by in-vivo single-particle tracking and microrheology measurements in Drosophila melanogaster embryos. EB-NS can be uptaken by plants and remotely detected in a low-cost stand-off detection setup. In summary, EB-NS have the potential for a wide range of bioimaging applications.

Remote near infrared identification of pathogens with multiplexed nanosensors

“…Therefore, we hypothesized that characteristic fluorescence changes even if not directly related to one target molecule could increase the discrimination power of the sensor array and decrease the impact of background signals. Last, we added a reference hydrogel with incorporated nanosheets of the calcium copper silicate Egyptian Blue (EB-NS, CaCuSi 4 O 10 ) as a highly stable reference NIR fluorophore at the lower end of the NIR emission capabilities of SWCNTs (emission at λ ≈ 920 nm) 63 . All 9 sensor hydrogels were then assembled into a stable 3 × 3 HG array, suitable for further integration into microbiological agar (Supplementary Figs.…”

Photophysical properties and fluorescence lifetime imaging of exfoliated near-infrared fluorescent silicate nanosheets

“…[14][15][16] A novel class of 2D materials are (phyllo)silicates such as Egyptian Blue (CaCuSi 4 O 10 , EB), which is as (exfoliated) nanosheet a promising uorophore for photonics. 17,18 This calcium copper tetrasilicate is regarded as the most ancient articial pigment made by mankind and dates back to Ancient Egypt (z 2500 BC), where it was employed in artwork. 19 EB's tetragonal crystal structure (space group P4/ncc) consists of parallel layers of silicate tetrahedra weakly held together by the presence of interlayer calcium ions in an eight-fold coordination geometry.…”

Exfoliation and Optical Properties of Near-Infrared Fluorescent Silicate Nanosheets

“…A novel class of 2D materials are (phyllo)silicates such as Egyptian Blue (CaCuSi4O10, EB), which is as (exfoliated) nanosheet a novel fluorophore for photonics [17,18] . This calcium copper tetrasilicate is regarded as the most ancient artificial pigment made by mankind and dates back to Ancient Egypt (≈ 2500 BC), where it was employed in artwork [19] .…”

“…Nevertheless, applications have been proposed as ink, fingerprint dusting powder, scaffold for selective enrichment of phosphopeptides or luminescent solar concentrators [27,[35][36][37][38][39] . Recently, it was shown that EB nanosheets (EB-NS) keep their NIR fluorescence properties and can serve as NIR fluorophore [17] .…”