Precision laser capture microdissection utilizing short pulse length

Abstract

Laser capture microdissection occurs where the transfer polymer film is placed on a substrate overlying visualized and selected cellular material from a sample for extraction. The transfer polymer film is focally activated (melted) with a pulse brief enough to allow the melted volume to be confined to that polymer directly irradiated. This invention uses brief pulses to reduce the thermal diffusion into surrounding non-irradiated polymer, preventing it from being heated hot enough to melt while providing sufficient heat by direct absorption in the small focal volume directly irradiated by the focused laser beam. This method can be used both in previously disclosed contact LCM, non contact LCM, using either condenser-side (or beam passes through polymer before tissue) or epi-irradiation (or laser passes through tissue before polymer). It can be used in configuration in which laser passes through tissue before polymer with and without an additional rigid substrate. In its preferred configuration it uses the inertial confinement of the surrounding unmelted thermoplastic polymer (and the overlying rigid substrate) to force expansion of the melted polymer into the underlying tissue target. Utilizing the short pulse protocol, the targeted and extracted material can have a diameter equal to or smaller than the exciting beam.