Laser-ablative Synthesis of Colloidal Nanomaterials for Biological Applications

Inorganic nanoparticles (plasmonic nanoparticles, semiconductor-based quantum dots etc) are known to offer novel promising properties for biological sensing and imaging, as well as for therapeutics. However, these applications are often complicated by potential toxicity issues, arising as a result of inadequate purification procedures of nanoparticles obtained via synthetic pathways using toxic or non-biocompatible substances. As an example, despite natural biocompatibility and biodegradability, Si nanoparticles cannot be chemically produced in pure state, as all chemical synthesis routes inevitably lead to their contamination by toxic by-products (HF derivatives etc). Pulsed laser ablation in liquids has recently emerged as a novel “green” tool for synthesis of colloidal nanomaterials, which offers a breakthrough in the solution of the toxicity problem. In this method, laser radiation is used to ablate a solid target in liquid ambience to form nanoclusters, which are then released into the liquid forming a colloidal nanoparticle solution. A huge advantage of this “physical” synthesis route consists in its independence on colloidal chemistry that enables one to avoid the employment of toxic substances or by-products. Indeed, nanomaterials are directly created from the bulk state, while the fabrication procedure can be carried out in clean environment (deionized water or aqueous biocompatible solutions).