Title: Prospects of Advanced Nonlinear Optical Materials for Biological Applications
We focus our research on novel materials, especially nanomaterials, exhibiting interesting nonlinear optical (NLO) properties that can lead to various practical applications. In particular, bio-related applications such as those in diagnostics and therapy are always very much in demand. Among the NLO phenomena that occur at high light intensities, nowadays readily obtainable from short-pulse lasers, such as frequency conversion, nonlinear refraction and nonlinear absorption, the most researched are those of two-photon absorption and various types of photon energy upconversion. Such effects can be exploited e.g. in photodynamic therapy carried out at relatively longer wavelengths than those at which typical photosensitizers operate .
From the materials engineering point of view, recent years have brought reports on a number of various “emerging” materials and nanomaterials that show promising NLO properties . While not all of these reports are entirely reliable, certain patterns appear that may indicate attractive directions of the future research. We are especially interested in effects that appear to be due to aggregation of chromophores, even in the case of relatively short wavelength transitions such as those in proteins without aromatic residues. Indeed, aggregated proteins such as amyloids, appear to show much enhanced NLO properties leading, among others, to efficient two-photon induced autofluorescence . Similar aggregation effects can lead to enhanced two- and multi-photon absorption in structures like metal-organic frameworks (MOFs) or cross-linked conjugated polymers .
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