gold ablation in waterToday, nanoparticles are widely implemented as functional elements on surfaces, into volumes and as nanohybrids, resulting for example in bioactive composites and nanobiomarkers. Nowadays, however, only a limited variety of materials that may be integrated into advanced functional materials are available: Nanoparticles synthesized by conventional gas phase processes are often agglomerated to micro powders that are hardly redispersible into functional matrices, and chemical methods often lead to impurities of the nanoparticle colloids caused by additives and precursor reaction products.

In the last decade, laser ablation and nanoparticle generation in liquids has proven to be a unique and efficient technique to generate, excite, fragment, and conjugate elemental, nanoalloy, semiconductor and ceramic nanoparticles. This exciting method bears strong advantages:

  • Laser-generated (metal) nanoparticles are charged and thus have an extremely high colloidal stability
  • In contrary to dry nanopowders, nanoparticle colloids are not inhalable and thus lead to an improved occupational safety
  • Chemical precursors are not required and thus the colloids are 100 percent pure
  • This method can be applied universally with an almost unlimited variety of materials and solvents

It recently has been shown that these advantages are of value in comparison to conventional synthesis, in particular

  • 3-5 times higher number of biomolecules may be conjugated to laser-generated, ligand-free gold nanoparticle surface
  • higher yields of laser-generated gold nanoparticle aptamer conjugates is beneficial especially if costly functional biomolecules are conjugated
  • lower noise during surface enhanced Raman scattering of laser-generated pure nanoparticles
  • ablation in polymer solution allows embeddding into polymer matrices for rapid nanomaterial prototyping

In ANGEL 2010, those topics have been discussed with exciting insights into physics and chemistry, like cavitation bubble dynamics and laser ablation in non-equilibrum liquids as huge variety of materials synthesized by pulsed laser ablation in liquids has been presented, from metals to photo-luminescent or ceramic materials. An emerging field is the laser excitation of particles, e.g. addressing size tuning, fragmentation or plasmon-enhanced laser nanobiosurgery. It was interesting to grab ideas on latest ablation chamber designs adapted to the respective investigations or drastically improved productivity.

Picking up the successful 2010 meeting, aspects of the fundamentals of laser ablation in liquids as well as novel applications were discussed at ANGEL 2012 and 2014.