- The ancient inorganic pigment Egyptian Blue is a fluorophore with outstanding near-infrared (NIR) performance and is thus considered as an emerging optical material that meets the current demand for cheap, efficient, and nontoxic NIR nanofluorophores. Herein, we present a protocol for the quick mass production of Egyptian Blue (CaCuSi4O10) nanosheets (EBNSs) with lateral size down to ∼100 nm by applying state-of-the-art ball-milling techniques. A systematic decay of the NIR photoluminescence behavior with decreasing size of the EBNSs was found, which challenges the desired application of EBNSs as bioimaging markers and other nanoapplications. To pave the way to surface modifications of EBNSs, we deposited a thin layer of silica on the surface of the EBNSs. Taking advantage of this modification, we subsequently performed surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization in order to grow both hydrophilic and hydrophobic polymer brushes from EBNSs, which enhanced dispersibility of the nanosheets andThe ancient inorganic pigment Egyptian Blue is a fluorophore with outstanding near-infrared (NIR) performance and is thus considered as an emerging optical material that meets the current demand for cheap, efficient, and nontoxic NIR nanofluorophores. Herein, we present a protocol for the quick mass production of Egyptian Blue (CaCuSi4O10) nanosheets (EBNSs) with lateral size down to ∼100 nm by applying state-of-the-art ball-milling techniques. A systematic decay of the NIR photoluminescence behavior with decreasing size of the EBNSs was found, which challenges the desired application of EBNSs as bioimaging markers and other nanoapplications. To pave the way to surface modifications of EBNSs, we deposited a thin layer of silica on the surface of the EBNSs. Taking advantage of this modification, we subsequently performed surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization in order to grow both hydrophilic and hydrophobic polymer brushes from EBNSs, which enhanced dispersibility of the nanosheets and even delivered function. By matching the refractive index of the EBNS with its polymer shell, the quality of the NIR photoluminescence of the EBNS could significantly be improved, since disturbing light scattering at the interface could effectively be suppressed. Our results provide a clear picture of the advantages and limitations of EBNSs as optical nanomaterials for NIR fluorescence applications.…

