Visible and NIR Upconverting Er³⁺–Yb³⁺ Luminescent Nanorattles and Other Hybrid PMO‐Inorganic Structures for In Vivo Nanothermometry

Abstract

Lanthanide-doped luminescent nanoparticles are an appealing system for nanothermometry with biomedical applications due to their sensitivity, reliability and minimally invasive thermal sensing properties. Here, we propose four unique hybrid organic-inorganic materials prepared by combining β-NaGdF4 and PMOs (Periodic Mesoporous Organosilica) or mSiO2 (mesoporous silica). PMO/mSiO2 materials are excellent candidates for biological/biomedical applications as they show high biocompatibility with the human body. On the other hand, the β-NaGdF4 matrix is an excellent host for doping lanthanide ions, even at very low concentrations with yet very efficient luminescence properties. We propose a new type of Er 3+ -Yb 3+ upconversion luminescence nanothermometers operating both in the visible and near infrared regime. Both spectral ranges permit promising thermometry performance even in aqueous environment. It is additionally confirmed that these hybrid materials are non-toxic to cells, which makes them very promising candidates for real biomedical thermometry applications. In several of these materials the presence of additional voids leaves space for future theranostic or combined thermometry and drug delivery applications in the hybrid nanostructures.

Luminescent Yb3+,Er3+-Doped α-La(IO3)3 Nanocrystals for Neuronal Network Bio-Imaging and Nanothermometry

“…From the ratiometric approach on the micro-PL setup, we measured a relative thermal sensitive S r of Yb 3+ ,Er 3+ -doped α-La(IO 3 ) 3 nanocrystals of 1.2% K −1 in neuronal cells, higher than previously reported values for other inorganic materials, including Green Fluorescent Proteins (GFP) [ 55 ], Nd 3+ -doped nanocrystals (0.1% K) [ 18 ], or quantum dots [ 56 ] ( Table 1 ). This value is comparable to that of other Er 3+ -doped materials [ 57 , 58 ] or hybrid materials [ 59 ], as a consequence of the energy gap between the two emitting levels of Er 3+ ( 4 S 3/2 and 2 H 11/2 ) whose splitting does not differ much with the host matrix. More complex systems, such as the association of rare-earth doped nanocrystals with chromophores presenting a triplet-triplet annihilation mechanism, can provide higher sensitivity (7% K −1 ) and high thermal resolution (0.1 K) [ 60 ].…”

Recent Advances in 2D Rare Earth Materials

“…[26,27,137] For example, Er 3+ is usually applied as an optical activator in RE and can be used for producing UC and DC emissions. [138][139][140] As shown in Figure 5a,b, Hao et al first achieved both UC and DC luminescence located in NIR spectral range in Er 3+ -doped MoS 2 excited by 980 nm laser. [70] For the UC process, the NIR emission at about 800 nm comes from the of 4I 9/2 -4I 15/2 energy transition of Er 3+ when excited at 980 nm.…”

“…[ 26,27,137 ] For example, Er 3+ is usually applied as an optical activator in RE and can be used for producing UC and DC emissions. [ 138–140 ] As shown in Figure a,b, Hao et al. first achieved both UC and DC luminescence located in NIR spectral range in Er 3+ ‐doped MoS 2 excited by 980 nm laser.…”

Rational Design of Ratiometric Luminescence Thermometry Based on Thermally Coupled Levels for Bioapplications

“…Under the unchanged acquisition setups, larger thermal sensitivity implies better temperature resolution and thermometric ability of optical sensors, thus most of works in are mainly focused on the thermal sensitivity. [ 34,48 ]…”