Co‐doping of iron and copper ions in nanosized bioactive glass by reactive laser fragmentation in liquids

Abstract

Bioactive glass (BG) is a frequently used biomaterial applicable in bone tissue engineering and known to be particularly effective when applied in nanoscopic dimensions. In this work, we employed the scalable reactive laser fragmentation in liquids method to produce nanosized 45S5 BG in the presence of light-absorbing Fe and Cu ions. Here, the function of the ions was twofold: (i) increasing the light absorption and thus causing a significant increase in laser fragmentation efficiency by a factor of 100 and (ii) doping the BG with bioactive metal ions up to 4 wt%. Our findings reveal an effective downsizing of the BG from micrometer-sized educts into nanoparticles having average diameters of <50 nm. This goes along with successful elementspecific incorporation of the metal ions into the BG, inducing co-doping of Fe and Cu ions as verified by energy-dispersive X-ray spectroscopy (EDX). In this context, the overall amorphous structure is retained, as evidenced by X-ray powder diffraction (XRD). We further demonstrate that the level of doping for both elements can be adjusted by changing the BG/ion concentration ratio during laser fragmentation.Consecutive ion release experiments using inductively-coupled plasma mass spectrometry (ICP-MS) were conducted to assess the potential bioactivity of the doped nanoscopic BG samples, and cell culture experiments using MG-63 osteoblast-like cells demonstrated their cytocompatibility. The elegant method of in situ co-doping of Fe and Cu ions during BG nanosizing may provide functionality-advanced biomaterials for future studies on angiogenesis or bone regeneration, particularly as the level of doping may be adjusted by ion concentrations and ion type in solution.bioactive ion doped bioglass, biocompatibility, biomaterials, bone tissue, engineering, laser doping | INTRODUCTION45S5 bioactive glass (BG) initially synthesized by Hench et al, 1 has advantages of controllable biodegradability, osteoconductivity and bioactivity. [2][3][4] BG can bind to bone tissue and stimulate bone regeneration by releasing Si 4+ , Ca 2+ , and PO 4 3À ions, 5 making it a successful bone graft. 6 To further enhance the dissolution, bioactivity, and protein-related bone therapeutics of BG, nanosized BG particle variants significantly increased in vitro

Laser-based ion doping is a suitable alternative to dope biologically active ions into colloidal bioglass nanoparticles

“…This is in contrast to our previous work using micrometer-sized BG particles, 18 where size reduction was observed. Thus, the laser-based ion doping technique allows us to evaluate doping effects independently from particle size effects.…”

“…Hence, nanosecond-pulsed UV laser excitation of nanoparticles in the low fluence regime applied here is most likely linked to a particle-surface-heating process, causing pulsed-laser-induced diffusion enhancement. 17 Furthermore, ion uptake specificity (higher affinity of Fe than Cu as found in 18 ) seems to be less pronounced (not dominant) at lower doping levels or in case no size reduction occurs. Upon co-doping with Sr, the Fe doping levels drastically increased by a factor of 9, so the presence of Sr seemed to promote Fe doping.…”

“…In previous work, laser doping of BG was only observed together with a laser fragmentation induced size reduction effect. 18 This size reduction increased the total surface area of the BG colloids as the mass remained constant. This, however, makes it impossible to differentiate a doping effect by the laser and stronger adsorption of the metal ions due to a larger available surface area.…”

“…Fe and Cu could be incorporated into the BG network, however, simultaneous reduction of particle size was observed. 18…”

“…Fe and Cu could be incorporated into the BG network, however, simultaneous reduction of particle size was observed. 18 Major advantages of the pulsed laser doping method include the facile control of doping levels by ion concentrations as well as the possibility for homogeneous ion incorporation. In previous work, laser doping of BG was only observed together with a laser fragmentation induced size reduction effect.…”