Assessing inter lanthanide photophysical interactions in co-doped titanium dioxide nanoparticles for multiplex assays

Abstract

This work assesses inter lanthanide photophysical interactions in titanium dioxide nanoparticles towards the development of multiplex assays.

Optimizing the Key Variables to Generate Host Sensitized Lanthanide Doped Semiconductor Nanoparticle Luminophores

“…Given the success in using semiconductor NPs to sensitize Ln 3+ * and the fact that the exciton pumping rate is not rate limiting, the possibility of incorporating more than one distinct Ln 3+ in an NP becomes a promising possibility. Indeed, experiments have demonstrated this phenomenon with the Ti­(NdSm)­O 2 NPs (average particle diameter = 2.6 ± 0.5 nm) and shown that the codoped NPs can produce nonoverlapping sharp emission bands at seven wavelengths spanning the orange-red to near-infrared spectral region, using a single excitation wavelength of 350 nm . A comparison of emission performance with their singly doped analogues indicates a decrease of Nd 3+ intensity by ∼6 times and of Sm 3+ intensity by ∼4.5 times (see Figure a).…”

“…This hypothesis was validated by performing control experiments with the Ti­(NdEr)­O 2 . In this system, the Nd 3+ near-infrared and Er 3+ visible emission decreases with respect to that in the corresponding singly doped NPs, however the Er 3+ near-infrared emission increases by ∼3 times in the codoped NPs (see Figure b, d) . Thus, “cross-talk” among Ln dopants will become an important new design constraint.…”

“… a ⟨τ⟩ = a 1 τ 1 + a 2 τ 2 with τ 1 and τ 2 being the two lifetime components having relative amplitudes of a 1 and a 2 , respectively. b Values are from ref . c Values are from ref . d Values are from ref . e Values are from ref . f Values are from ref . g Values are from ref . h Values are from ref . …”

“…Comparison of relative emissions in (a, b) synthetically codoped C­(LnLn′)­A NPs, (Reproduced from ref . with permission from Royal Society of Chemistry) (c, d) physically mixed C­(Ln)­A-C­(Ln′)­A NPs (where Ln, Ln′ = Nd, Sm or Nd, Er) and their corresponding singly and synthetically codoped counterparts is shown.…”

“…The Ln 3+ incorporation (in both synthetic and postsynthetic cases) has been demonstrated through observation of energy dispersive X-ray spectroscopic signatures for Ln 3+ in purified NPs, − and the increase in Ln 3+ photoluminescence in the NPs as compared to that found for free salts in bulk solvent. For postsynthetically modified II–VI NPs energy dispersive X-ray spectroscopy (EDS) showed (a) incorporation of Ln in the NPs, (b) significant changes in anion content of the NPs, and (c) an absence of complete cation exchange which is consistent with thermodynamic expectations .…”