The development of a thermoplastic film for laser capture microdissection system with near field tips

Laser capture microdissection (LCM) is a microscopy technique by the thermoplastic transfer film of ethylene vinyl acetate (EVA) for targeting and extraction of specific cell from tissue sections. Near-field optical tips were used to focus laser beam for replacing microscope objective of traditional LCM and successfully reduced the capture size to 500 nm. In this study, a method of producing a thinner thermoplastic film which adheres on a new mount with a hole is developed. Different thickness of the thermoplastic transfer film were made to find the relationship of the thermoplastic transfer film among the pulsing time of laser, the minimum capture size, and the droopy depth of melted spots. A copolymer of ethylene vinyl acetate (USI, UE653-04) was used as the major material of thermoplastic film. The results are mainly evaluated by the thickness gauge (Elcometer, 456) and atomic force microscopy (AFM). After comparing the films of different thickness, it was observed that when the films are in 100 μm thicknesses and under 100 ms pulsing time, the melted diameter of spot size is about 500 nm. The droopy depth of melted spots is about 140 nm. If it is thinner than 100 μm, which is used in traditional LCM system, the pulsing time may be shorter to reach the same droopy depth. In brief, the study successfully completed the processing of making the transparent thermoplastic films on the designed cannular mount. In this way, further development of the new LCM system in nano-captures is provided.