In vivo fluorescence imaging of the transport of charged chlorine6 conjugates in a rat orthotopic prostate tumour

Polymeric drug conjugates are used in cancer therapy and, varying their molecular size and charge, will affect their in vivo transport and extravasation in tumours. Partitioning between tumour vasculature and tumour tissue will be of particular significance in the case of photosensitizer conjugates used in photodynamic therapy, where this partitioning can lead to different therapeutic effects. Poly-l-lysine chlorine6 conjugates (derived from polymers of averageMr 5000 and 25 000) were prepared both in a cationic state and by poly-succinylation in an anionic state. A fluorescence scanning laser microscope was used to follow the pharmacokinetics of these conjugates in vivo in an orthotopic rat prostate cancer model obtained with MatLyLu cells. Fluorescence was excited with the 454–528 nm group of lines of an argon laser and a 570 nm long pass filter used to isolate the emission. Results showed that the conjugates initially bound to the walls of the vasculature, before extravasating into the tissue, and eventually increasing in fluorescence. The anionic conjugates produced tissue fluorescence faster than the cationic ones, and surprisingly, the largerMr conjugates produced tissue fluorescence faster than the smaller ones with the same charge. These results are consistent with differences in aggregation state between conjugates. © 1999 Cancer Research Campaig

Nonlinear Optics

This chapter provides a brief introduction into the basic nonlinear-optical phenomena and discusses some of the most significant recent advances and breakthroughs in nonlinear optics, as well as novel applications of nonlinear-optical processes and devices. Nonlinear optics is the area of optics that studies the interaction of light with matter in the regime where the response of the material system to the applied electromagnetic field is nonlinear in the amplitude of this field. At low light intensities, typical of non-laser sources, the properties of materials remain independent of the intensity of illumination. The superposition principle holds true in this regime, and light waves can pass through materials or be reflected from boundaries and interfaces without interacting with each other. Laser sources, on the other hand, can provide sufficiently high light intensities to modify the optical properties of materials. Light waves can then interact with each other, exchanging momentum and energy, and the superposition principle is no longer valid. This interaction of light waves can result in the generation of optical fields at new frequencies, including optical harmonics of incident radiation or sum- or difference-frequency signals