Molecular engineering of NLO-phores for new NLO microscopies

Novel microscopies based on nonlinear optical (NLO) phenomena such as two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) have gained overwhelming popularity in the biology community owing to the many advantages they provide in biological imaging. Examples of molecular engineering approaches toward NLO-probes specifically designed for SHG and/or TPEF imaging of lipid membranes and biological cells are given here, providing an illustration of their intriguing potential in the area of real-time, non-damaging imaging of biological structures. Optimized NLO-markers open new routes for improved monitoring and better understanding of fundamental dynamic processes.