Nanoprobes with near-infrared persistent luminescence for in vivo imaging

Abstract

Fluorescence is increasingly used for in vivo imaging and has provided remarkable results. Yet this technique presents several limitations, especially due to tissue autofluorescence under external illumination and weak tissue penetration of low wavelength excitation light. We have developed an alternative optical imaging technique by using persistent luminescent nanoparticles suitable for small animal imaging. These nanoparticles can be excited before injection, and their in vivo distribution can be followed in real-time for more than 1 h without the need for any external illumination source. Chemical modification of the nanoparticles' surface led to lung or liver targeting or to long-lasting blood circulation. Tumor mass could also be identified on a mouse model. biodistribution ͉ in vivo optical imaging ͉ nanoparticles ͉ phosphorescent nanoparticles

In Vivo Repeatedly Charging Near‐Infrared‐Emitting Mesoporous SiO2/ZnGa2O4:Cr3+ Persistent Luminescence Nanocomposites

“…[1,4,7] The PL excitation band from 600 to 650 nm is in the transmission window of biological tissue (600–1100 nm) [12] and thus gives us the opportunity to recharge the energy-exhausted mZGC in deep tissue in situ. Since there is no standard method to accurately evaluate the deep-tissue-imaging ability of PL phosphors, we propose a meat-covering method for comparison according to our previous report on up-conversion imaging (Figure 3A).…”

“…[1–3] The temporal separation of excitation and afterglow properties of these persistent phosphors makes them ideal as in vivo optical imaging contrast reagents. [4–6] Until now, persistent luminescence has relied on short-wavelength excitation (e.g., ultraviolet light) which has rather limited tissue-penetration depth. [7–10] To address this problem, a NIR-light-stimulated PL mechanism was proposed in LiGa 5 O 8 :Cr 3+ , to release energy trapped in deeper energy levels of the phosphor, but in this case, the energy must be precharged by UV-light and the photostimulated emission continues to weaken after each cycle of photostimulation and will finally become extinguished.…”

Progress on lanthanide-based organic–inorganic hybrid phosphors

“…There has been growing interest also in the use of NIR light, this being one of the best strategies for acquiring high-resolution pictures of deep tissues, as NIR light diffracts much less than visible light. 47 A promising idea investigated by Masne-de-Chermont et al 48 is the use of long-lasting luminescent NPs for in vivo imaging. The phosphors are based on poly(ethylene glycol)-decorated MgSiO 3 : Eu,Dy,Mn NPs (divalent europium and manganese ions), in order to ensure biocompatibility and targeting action (lung, liver or blood circulation).…”

The importance of inversion disorder in the visible light induced persistent luminescence in Cr3+doped AB2O4(A = Zn or Mg and B = Ga or Al)

“…1 These materials known as persistent phosphors, were demonstrated to be used as probes for in vivo small animal optical imaging in 2007, when emitting in the red or near infrared (NIR) range. 2 This technique is advantageous over conventional fluorescence techniques as it avoids autofluorescence of body tissues under continuous illumination and thus improves the signal to noise ratio. The technique of in vivo imaging was first demonstrated using silicate nanoparticles with composition Ca 0.2 Zn 0.9 Mg 0.9 Si 2 O 6 :Eu 2+ , Dy 3+ , Mn 2+ (CZMSO), with 2.5 mol% of Mn 2+ luminescent ion doping.…”