Luminescence Enhanced Eu³⁺/Gd³⁺ Co-Doped Hydroxyapatite Nanocrystals as Imaging Agents In Vitro and In Vivo

Abstract

Biocompatible, biodegradable, and luminescent nano material can be used as an alternative bioimaging agent for early cancer diagnosis, which is crucial to achieve successful treatment. Hydroxyapatite (HAP) nanocyrstals have good biocompatibility and biodegradability, and can be used as an excellent host for luminescent rare earth elements. In this study, based on the energy transfer from Gd(3+) to Eu(3+), the luminescence enhanced imaging agent of Eu/Gd codoping HAP (HAP:Eu/Gd) nanocrystals are obtained via coprecipitation with plate-like shape and no change in crystal phase composition. The luminescence can be much elevated (up to about 120%) with a nonlinear increase versus Gd doping content, which is due to the energy transfer ((6)PJ of Gd(3+) → (5)HJ of Eu(3+)) under 273 nm and the possible combination effect of the cooperative upconversion and the successive energy transfer under 394 nm, respectively. Results demonstrate that the biocompatible HAP:Eu/Gd nanocrystals can successfully perform cell labeling and in vivo imaging. The intracellular HAP:Eu/Gd nanocrystals display good biodegradability with a cumulative degradation of about 65% after 72 h. This biocompatible, biodegradable, and luminescence enhanced HAP:Eu/Gd nanocrystal has the potential to act as a fluorescent imaging agent in vitro and in vivo.

Calcium Phosphate as a Key Material for Socially Responsible Tissue Engineering

“…Although the last ionic additives incorporable into CAP will soon be off the list in terms of being integrated into CAP and limitedly characterized for their properties, it will be a while before even the tip of the iceberg of possibilities achievable through the synergy amongst different ionic dopants is revealed. Some of such simultaneous incorporations of two or more types of ions into CAP, such as silver and lanthanides [ 75 ], zinc and magnesium [ 76 ], selenite and manganese [ 77 ], europium and gadolinium [ 78 ], have already been tested for their multifunctional properties.…”

Effect of the Fluorine Substitution for –OH Group on the Luminescence Property of Eu3+ Doped Hydroxyapatite

“…Recently, more attention has been put by the researchers toward the luminescence performance of RE ions in natural as well as synthesized apatites. The main focus for the study of RE ions doped with HAp has been the enhancement of luminescence with previous results showing the possibility of improving luminescence performance of RE elements doped HAp by increasing the RE content [11], calcination [3], and co-doping of RE ions [12][13][14]. However, they are accompanied by certain issues like quenching effect, oversize, severe aggregation, and toxicity.…”

Nano-hydroxyapatite polymeric hydrogels for dye removal

“…10 , 11 Due to its biocompatibility, osteoconductivity, biodegradability and synthetic nanostructures (calcium and phosphorus combined hydroxide) as well as an affinity for polymers. 12 – 14 Therefore, hydroxyapatite has been used in the preparation of polymeric composite materials with various polymers, such as chitosan, alginate, cellulose, collagen, poly(lactic acid), poly(ε-caprolactone) for engineering applications. 15 Hydroxyapatite can be synthesized from the waste of fish bones, egg shells, oyster shells, coral, algae and other biogenic sources for respective applications.…”