As a tribute to a dear colleague, Olivier Poizat, whose humility, exemplary probity and demanding science must serve as an inspiring model for the younger generation of scientists. Highly concentrated dispersions of fluorescent organic nanoparticles (FONs), broadly used for optical tracking, bioimaging and drug delivery monitoring, are obtained using a newly designed micromixer chamber involving high impacting flows. Fine size tuning and narrow size distributions are easily obtained by varying independently the flow rates of the injected fluids and the concentration of the dye stock solution. The flash nanoprecipitation process employed herein is successfully applied to the fabrication of bicomposite FONs designed to allow energy transfer. Considerable enhancement of the emission signal of the energy acceptors is promoted and its origin is found to result from polarity rather than steric effects. Finally, we exploit the high spatial confinement encountered in FONs and their ability to encapsulate hydrophobic photosensitizers to induce photocrosslinking. An increase in the photocrosslinked FON stiffness is evidenced by measuring the elastic modulus at the nanoscale using atomic force microscopy. These results pave the way toward the straightforward fabrication of multifunctional and mechanically photoswitchable FONs, opening novel opportunities in sensing, multimodal imaging, and theranostics.

Development of a nanocarrier using micelles and bimodal imaging to monitor drug delivery and evaluate efficacy. Sonoporation treatment enables safe and effective delivery of micelles to the tumor.

The Front Cover illustrates the fabrication of highly concentrated dispersions of fluorescent organic nanoparticles (FONs) using a microfluidic chamber with high impacting flows, allowing for fine size control (picture courtesy of Jules Bellettre alias PRBLMS). More information can be found in the Article by E. Ishow and co‐workers.