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Trivalent Nd and Yb co-doped rod shaped hexagonal phase fluorapatite (FAP) nanoparticles of length and width about 32 and 13 nm, respectively were prepared by hydrothermal method and investigated the ability for 980 nm emission via Nd 3+ → Yb 3+ energy transfer with the objective of utilizing them in biomedical imaging. Nd 3+ → Yb 3+ energy transfer in FAP was studied as a function of both Nd 3+ and Yb 3+ concentrations and found that when Yb 3+ concentration was 10 mol% the FAP phase has partially turned in to YbPO 4 phase. The Yb 3+ emission intensity at 980 nm significantly increased up to 5 mol% Yb 3+ doping and then reduced drastically for further increase in its concentration. Nd 3+ →Yb 3+ energy transfer rates were evaluated from the decay curves and found that a transfer rate of 71% for 2 mol% Nd 3+ co-doped with 5 mol% Yb 3+ . The cytocompatibility test with fibroblast like cells using MTT assay revealed that the nanoparticles are compatible with the cells. [ABSTRACT FROM AUTHOR]

In the present work, surface modification of iron oxide (Fe 3 O 4 ) nanoparticles with biocompatible fluorapatite (FAP) coating achieved by a simple method and their characterizations using XRD, TEM, FT-IR, DSC and VSM are reported. TEM images revealed the spherical morphology of Fe 3 O 4 nanoparticle and rod-like FAP coated Fe 3 O 4 nanoparticles with size of about 12 and 30 nm, respectively. Magnetic measurements (M-H) of both the samples exhibited superparamagnetic behavior at 300 K. FAP coated Fe 3 O 4 nanoparticles enhance the cell viability and colloidal stability when compared to Fe 3 O 4 nanoparticles. These results demonstrate that FAP coated Fe 3 O 4 nanoparticles could be a suitable candidate for biomedical applications. [ABSTRACT FROM AUTHOR]

Trivalent Yb and Er doped fluoroapatite nanoparticles were prepared by a microwave assisted wet precipitation method using calcium nitrate tetrahydrate, diammonium hydrogen phosphate, ammonium fluoride and Yb, Er nitrate tetrahydrate as precursors. Well crystallized nanoparticles of rod like morphology with length and width of about 26 ± 3 and 9 ± 2 nm was obtained. Under 980 nm excitation the nanoparticles exhibit strong near infrared emission at 1532 nm with a maximum measured internal quantum yield of 74% in 3 mol% Er and 9 mol% Yb doped sample which is 26% less than the 100% radiative quantum yield predicted by Judd-Ofelt procedure. The measured quantum yield shows a linear dependence of quantum yield on Yb concentration. [ABSTRACT FROM AUTHOR]