The in vivo activation of persistent nanophosphors for optical imaging of vascularization, tumours and grafted cells

Abstract

Optical imaging for biological applications requires more sensitive tools. Near-infrared persistent luminescence nanoparticles enable highly sensitive in vivo optical detection and complete avoidance of tissue autofluorescence. However, the actual generation of persistent luminescence nanoparticles necessitates ex vivo activation before systemic administration, which prevents long-term imaging in living animals. Here, we introduce a new generation of optical nanoprobes, based on chromium-doped zinc gallate, whose persistent luminescence can be activated in vivo through living tissues using highly penetrating low-energy red photons. Surface functionalization of this photonic probe can be adjusted to favour multiple biomedical applications such as tumour targeting. Notably, we show that cells can endocytose these nanoparticles in vitro and that, after intravenous injection, we can track labelled cells in vivo and follow their biodistribution by a simple whole animal optical detection, opening new perspectives for cell therapy research and for a variety of diagnosis applications.

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

“…[20] Among these bands, the absorbance at 600–650 nm is responsible for the in vivo recharging by using deeper-tissue-penetrating red light. [12] The PL spectrum (Figure 1C) of the mZGC, which is around 696 nm (inside the NIR imaging window, which ranges from 650 to 900 nm), is also consistent with the results found in the traditional solid-state reaction. [20–22] The PL of ZGC can be detected even after more than 5 h followed by an excitation for 5 min with an UV light source (254 nm; Figure 1D).…”

“…[3,11] Very recently, the PL phosphor, ZnGa 2 O 4 :Cr 3+ (ZGC), was found to be activatable by using tissue-penetrable red light, which means that energy can be recharged and NIR PL imaging is no longer limited by the luminescence-decay life-time of the phosphor. [12] Thus ZGC is arguably the optimal rechargeable NIR persistent emitting phosphor reported to date. Despite such inspiring progress, the production of uniformly structured NIR PL ZGC phosphors remains challenging.…”

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)

“…Also, this distinctive property of d-ZGO to show LLP with laser excitation renders the possibility for re-excitation of the ZGO nanoparticles inside the animal body by visible light illumination, making it a favourable candidate for the application of in vivo imaging. 4,5 Comparison of emission spectra recorded for d-ZGO and d-ZAO compounds during the excitation and during LLP emission (after the end of excitation) are shown in Figure 3. Emission spectra measured during X-ray excitation (Figure 3 (a)) show intense R-line for both the compounds, and corresponds to the 2 E → 4 A 2 ZPL of Cr 3+ .…”

Tailored Near‐Infrared Photoemission in Fluoride Perovskites through Activator Aggregation and Super‐Exchange between Divalent Manganese Ions

“…Besides, luminescent materials that emit in the NIR (700–1100 nm) themselves are attractive for a variety of applications. Recently, the most vibrant field of interest in this context has been in the area of biomedical imaging, where cells and tissue exhibit weak autofluorescence and low transmission loss for optical signals just within the NIR 22, 23. It has hence been crucial to design (nano) materials that exhibit both emission and excitation of luminescence in the NIR region for in vitro and in vivo imaging applications 24, 25.…”