Selective cell destruction and precise neurite transection in neuroblastoma cultures with pulsed ultraviolet laser microbeam irradiation: An analysis of mechanisms and transection reliability with light and scanning electron microscopy

Abstract

Ultraviolet (UV) laser pulses at 337 nm and 12 nsec were used as an effective surgical tool for the elimination of cells and the transection of cellular processes in culture. Analyses of lased neuroblastoma cells with light and scanning electron microscopy show that precise, immediate lesions of 0.5 μm to 2 μm can be produced using either of two techniques: (1) direct laser transections at energy densities above 12 μJ/μm 2; and (2) indirect transections by involving the substrate in the surgery process at energy densities ranging from 1 to 12 μJ/μm 2. The first technique uses cytoplasmic cavitations in the laser focus; the second depends on shock waves created by vaporizing substrate. Damage thresholds have been established for commonly used tissue culture materials and for unpigmented cytoplasm. Thresholds for all plastics tested lie below that of unpigmented cytoplasm making the direct transection technique inapplicable because of the formation of large, destructive shock waves. A reduction of energy densities to the damage thresholds of specific substrate materials allows the production of minute shock waves that create the highly localized damage required for reliable, precise and non-lethal cell surgery in culture.