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An atomic force microscopic method to study the incubation states of UV laser irradiated polymer samples is presented. Targets were illuminated by different number of pulses at 5.8 and 8.9 mJ/cm2 fluences. The induced adhesive and morphological changes were investigated simultaneously by an atomic force microscope equipped with a pulsed force mode extension. Importantly, below 100 pulses morphological changes were not observable while significant changes in the adhesion were found as a result of the incubation at 8.9 mJ/cm2 fluence. This method allows the imaging and detection of the whole laser modified area with nanometer resolution. [ABSTRACT FROM AUTHOR]

We present an investigation on absorbing film assisted laser induced forward transfer (AFA-LIFT) of fungus (Trichoderma) conidia. A KrF excimer laser beam [λ=248 nm,FWHM=30 ns (FWHM, full width at half maximum)] was directed through a quartz plate and focused onto its silver coated surface where conidia of the Trichoderma strain were uniformly spread. The laser fluence was varied in the range of 0–2600 mJ/cm2 and each laser pulse transferred a pixel of target material. The average irradiated area was 8×10-2 mm2. After the transfer procedure, the yeast extract medium covered glass slide and the transferred conidia patterns were incubated for 20 h and then observed using an optical microscope. The transferred conidia pixels were germinated and the areas of the culture medium surfaces covered by the pixels were evaluated as a function of laser fluence. As the laser fluence was increased from 0 to 355 mJ/cm2 the transferred and germinated pixel area increased from 0 to 0.25 mm2. Further increase in fluence resulted in a drastic decrease down to an approximately constant value of 0.06 mm2. The yield of successful transfer by AFA-LIFT and germination was as much as 75% at 355 mJ/cm2. The results prove that AFA-LIFT can successfully be applied for the controlled transfer of biological objects. [ABSTRACT FROM AUTHOR]

The survival, proliferation, and differentiation of freshly isolated and cultured cells were studied after absorbing film-assisted laser-induced forward transfer. Rat Schwann and astroglial cells and pig lens epithelial cells were used for transfer and the cells were cultured for 2 weeks after laser-pulsed transfer. All three cell types survived, proliferated, and differentiated under cell culture conditions and regained their original phenotype a few days after cell transfer. Time resolution studies have shown that the time required to accelerate the jets and droplets containing the cells was less than 1 micros and that the estimated minimum average acceleration of those ejected cells that reached a constant velocity was approximately 10(7) x g. This suggests that the majority of studied cells tolerated the extremely high acceleration at the beginning of the ejection and the deceleration during impact on the acceptor plate without significant damage to the original phenotype. These results suggest that the absorbing film-assisted laser-induced forward transfer technique appears to be suitable for several potential applications in tissue engineering and the biomedical tissue repair technologies.