Copper Indium Sulfide Quantum Dots as Nanomanometers: Influence of Size and Composition

Mechanical forces control the function of organisms and mediate theinteraction between biological systems and their environments. Knowledge ofthese forces will increase the understanding of biological processes and cansupport the development of novel diagnostic and therapeutic procedures.Although techniques like atomic force microscopy and droplet insertionmethod allow measuring forces over a broad range of values, they are invasiveand lack versatility. A promising way to overcome these hurdles isluminescent nanomanometry. Quantum dots (QDs) specifically have opticalproperties that depend on their size because of the quantum confinement,which makes them responsive to applied forces. Yet, a fine understanding ofhow fundamental parameters affect the response to applied stress is requiredbefore a QD family can be credibly proposed as luminescentnanomanometers. Here, a thorough study is conducted on how size andstoichiometry affect the nanomanometry performance of CuInS2QDs. Thestudied QDs feature pressure-dependent photoluminescence in thered/near-infrared range, which can enable the measurement of mechanicalforces in the range of physiological relevance in a remote and minimallyinvasive way. It is shown that tuning size and stoichiometry cansimultaneously enhance the CuInS2QDs’ brightness and response to appliedpressure, thus providing guidelines for better luminescent nanomanometers.