Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays.

Christoph Rehbock,Stephan Barcikowski,Selina Van Der Meer,Lisa Gamrad,Detlef Rath,Ulrike Taylor,Wilfried Kues,Jurij Jakobi,Daniela Tiedemann

doi:10.3762/bjnano.5.165

Christoph Rehbock, Stephan Barcikowski + Show 7 more

Open Access

https://doi.org/10.3762/bjnano.5.165

Copy DOI

Abstract

Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4–400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag+ ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered.

Highlights

The widespread use of medical implants consisting of metals and alloys (e.g., NiTi, CoCr, stainless steel) [2,3,4] makes an adequate assessment of their toxicity a major issue, as implants are designed to remain in contact with biological systems for years
As pulsed laser fragmentation in liquid (PLFL) primarily yields smaller nanoparticles, a second postirradiation strategy, suitable for the synthesis of larger particles is pulsed laser melting in liquid (PLML), which requires aggregated starting material [71] to be post-irradiated at moderate laser fluence
In this paragraph we reviewed that size control of ligand-free gold nanoparticles may be basically performed by four different strategies including 1) pulsed laser melting in liquid, 2) delayed bioconjugation in liquid-flow, 3) addition of low salinity electrolytes and 4) pulsed laser fragmentation in liquid

Summary

Introduction

The widespread use of medical implants consisting of metals (e.g., gold coatings [1]) and alloys (e.g., NiTi, CoCr, stainless steel) [2,3,4] makes an adequate assessment of their toxicity a major issue, as implants are designed to remain in contact with biological systems for years. Even though many groups used organic stabilizers such as citrate [59,66] or sodium dodecyl sulfate (SDS) [67], Amendola and Meneghetti [68] could show that size reduction might as well be exercised in totally ligand-free environments, where the application of nanosecond pulses at λ = 532 nm enables control of the particle diameters in a range from 4–30 nm for a variation of the laser fluence from 12–442 mJ/cm2 (Figure 2B).

Results

Conclusion