AMADEus Seminars - Prof. Koen Clays - Friday 8 march 2019 - 2:00 pm - ISM (Salle de conférence) & Wednesday 13 march 2019 - 10:00 am - CRPP (Amphi)08/03 : 14h
Molecular Imaging and Photonics
2019.03.08# Development of molecular probes for cellular imaging combining second-harmonic generation, two-photon fluorescence and membrane potential measurment
2019.03.13# Ultrafast revealing of invisible patterns encrypted in colloidal photonic crystals
Friday 8 March 2019 – 2:00 pm - ISM (conference room)
"Development of molecular probes for cellular imaging combining second-harmonic generation, two-photon fluorescence and membrane potential measurment"
We review the development of molecular, exogenic probes for the application of nonlinear optical imaging and membrane potential measurement. The emphasis necessarily is on requirements for second-harmonic imaging, because of the more stringent non-centrosymmetry requirements imposed at both the molecular and the structural level. We focus on the application in cellular imaging, where the challenge is the specificity. Because of the serendipitous use of charges on the probes for the optimization of both the amphiphilic and the optical properties, we recall how hyper-Rayleigh scattering has been instrumental in this development. This also holds true for the fluorescent proteins and examples of fluorescent and chromoproteins for nonlinear imaging will be presented. Recent results on membrane potential measurements will be discussed.
Wednesday 13 March 2019 - 10:00 am - CRPP (amphi)
"Ultrafast revealing of invisible patterns encrypted in colloidal photonic crystals"
After an introduction to colloidal photonic crystals and an overview of our earlier work in this field, we describe the necessary steps towards the realization of ultrafast revealing of invisible patterns encrypted in colloidal photonic crystals. These include the development of hollow air-core – dense-silica-shell core-shell monodisperse and spherical nanoparticles; introducing of a pattern of hydrophilic regions in a hydrophobic surrounding; and the combination of these two approaches by selective oxygen plasma etching of hollow core-shell nanospheres. The pattern imprinted by the difference in only surface property remains invisible in normal conditions of static environmental humidity. The hydrophilic regions in the patterns are reversible and immediately unveiled by dynamic humid flow. The specific properties of a human breath in terms of relative humidity and vapor flow are ideal for optimal revealing in terms of the spectral shift of the photonic bandgap of the colloidal crystal. The revealing of the pattern is determined by the surface tension of the vapor, while the color of the imprinted pattern is independently determined by its refractive index.