Laser ablation and the production of polymer films.

The formation of high-quality thin films of polytetrafluoroethylene (PTFE) is important in many applications ranging from material reinforcement to molecular electronics. Laser ablation, a technique widely used to deposit a variety of inorganic materials, can also be used as a simple and highly versatile method for forming thin polymer films. The data presented show that PTFE films can be produced on various supports by the evaporation of a solid PTFE target with a pulsed ultraviolet laser. The composition of the ablation plume suggests that PTFE ablation and subsequent film formation occur by way of a laser-induced pyrolitic decomposition with subsequent repolymerization. The polymer films produced by this method are composed of amorphous and highly crystalline regions, the latter being predominantly in a chain-folded configuration with the molecular axis aligned parallel to the substrate surface.

Laser micromanipulation in the mouse embryo: a novel approach to zona drilling.

OBJECTIVE: To introduce the use of excimer lasers for penetration of the zona pellucida for micromanipulation purposes. DESIGN: Cryopreserved two-cell mouse embryos were thawed and exposed to the 248-nm line of a krypton fluoride excimer laser (Lambda Physik EMG 202, Goettingen, Germany) creating a 2 to 4-micron opening in the zona pellucida. SETTING: The Laser Ablation Laboratory at DuPont and the in Vitro Fertilization Laboratory at The Medical Center. INTERVENTIONS: The embryos were exposed in either phosphate-buffered solution (PBS) or modified human tubal fluid (HTF) with the laser power varying from 1 to 2 J/cm2 and cultured in Ham's F-10 medium (GIBCO, Grand Island, NY) with 0.4% bovine serum albumin. MAIN OUTCOME MEASURES: The outcome of each experiment was measured by blastocyst formation of laser-exposed embryos as compared with a set of unexposed control embryos handled in a similar fashion. RESULTS: Successful laser penetration of the zona pellucida was achieved using the 248-nm line of a krypton fluoride excimer laser. A higher blastocyst formation was found for embryos exposed in PBS. The higher optical absorption of the modified HTF partially inhibited embryo development. The blastocyst statistics increased 2.5-fold times by reducing the exposure of the embryos to ablation by-products. CONCLUSIONS: The use of a krypton fluoride excimer laser was introduced as a new method to open the zona pellucida of two-cell mouse embryos without interrupting blastocyst formation.