Lighting Nanoscale Insulator by Steric Restriction Induced Emissions

Luminescence detection is a sensitive approach for high-resolution visualization of nano-/macro-sized objects in complex media, but it’s challenging to light the invisible insulators owing to their inert surfaces. Herein, we discovered a steric restriction induced emission (SRIE) effect on nanoscale insulators to light them by fluorogenic probes. The SRIE effect enabled to specifically differentiate a representative nanoscale insulator, boron nitride (BN) nanosheet from 18 tested nanomaterials with 420-fold increments of photoluminescence intensity and display three-order of magnitude linearity for quantitative analysis as well as single-particle-level detections. Molecular dynamics simulations indicated that the hydrophobic and electron-resistant surface of BN nanosheets restricted the intramolecular motions of fluorogenic molecules for blockage of the nonradiative path of excited electrons and activation of the radiative electron transition. Moreover, the lighted BN nanosheets could be successfully visualized in complex cellular and tissue bio-contexts. Overall, the SRIE effect will inspire more detection techniques for inert materials.