Femtosecond Laser Prints Biomolecules

Daniel S. Burgess

Dense, high-resolution patterns of various biological molecules have been fabricated using direct laser printing with a source of 500-fs ultraviolet pulses. Demonstrated at the Foundation for Research and Technology — Hellas’ Institute of Electronic Structure and Laser and the Institute of Molecular Biology and Biotechnology, both in Heraklion, Greece, the printing technique has potential applications in the preparation of biosensors and microarray chips.

Femtosecond pulses of ultraviolet laser radiation free biological molecules from a substrate and transfer them to a target. The direct laser printing process, which has a resolution of 50 μm, does not damage the biomaterials, as this active enzyme staining reaction of deposited horseradish peroxidase demonstrates. Courtesy of Ioanna Zergioti.

Current methods for the high-resolution deposition of biomaterials, the researchers note, display variability in the size of the samples, are uneconomical for use with valuable samples and/or require expensive processing equipment. Direct laser printing, they suggest, is versatile and suitable for use even with relatively unstable molecules.

In this technique, a film of the biomaterial is exposed to 10-mJ pulses of 248-nm radiation from a distributed feedback dye/KrF laser, freeing the material from the silica substrate and transferring it to a target positioned approximately 10 μm away. Employing femtosecond pulses reduces the energy required for transfer as well as the thermal effects, minimizing potential damage to the molecules.

To demonstrate, the investigators printed glass slides with patterns of 50 × 50-μm spots of lambda bacteriophage DNA, bovine serum albumin and glutathione S-transferase protein. Subsequent hybridization reactions and binding experiments with tagged antibodies confirmed that the biomaterials were not altered in the transfer process.

Further research is ongoing in collaboration with the National Technical University of Athens, Greece.

Applied Physics Letters, April 18, 2005, 163902.