Single-Step Process for Titanium Surface Micro- and Nano-Structuring and In Situ Silver Nanoparticles Formation by Ultra-Short Laser Patterning

Abstract

Ultra-short laser (USL)-induced surface structuring combined with nanoparticles synthesis by multiphoton photoreduction represents a novel single-step approach for commercially pure titanium (cp-Ti) surface enhancement. Such a combination leads to the formation of distinct topographical features covered by nanoparticles. The USL processing of cp-Ti in an aqueous solution of silver nitrate (AgNO3) induces the formation of micron-sized spikes surmounted by silver nanoparticles (AgNPs). The proposed approach combines the structuring and oxidation of the Ti surface and the synthesis of AgNPs in a one-step process, without the use of additional chemicals or a complex apparatus. Such a process is easy to implement, versatile and sustainable compared to alternative methodologies capable of obtaining comparable results. Antimicrobial surfaces on medical devices (e.g., surgical tools or implants), for which titanium is widely used, can be realized due to the simultaneous presence of AgNPs and micro/nano-structured surface topography. The processed surfaces were examined by means of a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and Raman spectroscopy. The surface morphology and the oxidation, quality and quantity of AgNPs were analyzed in relation to process parameters (laser scanning speed and AgNO3 concentration), as well as the effect of AgNPs on the Raman signal of Titanium oxide.

Surface structuring and in situ synthesis of nanoparticles by ultrashort laser processing on hydroxyapatite

“…The second exposure uses a lower dose of energy (lower laser power and higher scanning speed), not sufficient to further ablate the HA surface. The use of USL to obtain surface structuring and particles deposition has been explored on different materials for various applications [21,22,23], however, there is no example of using such an approach with HA or other bioceramics. The presence of micro features on the material surface can facilitate cell adhesion and proliferation improving the integration between the material and the host tissue.…”

Improvement of Metal-Doped β-TCP Scaffolds for Active Bone Substitutes via Ultra-Short Laser Structuring

“…Thermal effects can be avoided by the application of ultra-short laser pulses. These pulses, due to their short duration, interact with the materials in such a way that energy is delivered only to the electrons and not to the full crystal lattice, leaving the latter unaffected by thermal effects [23][24][25]. This is of major importance when using laser ablation on materials that would otherwise suffer thermal degradation, and it is a key aspect that makes the application of ultra-short pulses for texturing metals, polymers, and ceramics possible [26].…”

“…For example, Götz et al [27] used a femto-second laser to produce a laser-structured titanium alloy (Ti6Al4V) capable of improving osteointegration 12 weeks after implantation in rabbit models. On this same material, Aceti et al developed a process for the deposition of in situ silver nanoparticle formation and nano-and micro-structuring of metal surfaces via ultra-short laser patterning, where particles are produced in aqueous solution via multiphoton photoreduction and deposited in the metal upon laser patterning, providing a green and cost-effective alternative for the functionalization of Ti surfaces and achieving a synergetic effect between the nanostructure and the antibacterial particles [24]. Sotelo et al have also noted the generation of LIPSS on titanium and stainless steel.…”