Controlling Electron Trap Depth To Enhance Optical Properties of Persistent Luminescence Nanoparticles for In Vivo Imaging

Abstract

Focusing on the use of nanophosphors for in vivo imaging and diagnosis applications, we used thermally stimulated luminescence (TSL) measurements to study the influence of trivalent lanthanide Ln(3+) (Ln = Dy, Pr, Ce, Nd) electron traps on the optical properties of Mn(2+)-doped diopside-based persistent luminescence nanoparticles. This work reveals that Pr(3+) is the most suitable Ln(3+) electron trap in the diopside lattice, providing optimal trap depth for room temperature afterglow and resulting in the most intense luminescence decay curve after X-ray irradiation. This luminescence dependency toward the electron trap is maintained through additional doping with Eu(2+), allowing UV-light excitation, critical for bioimaging applications in living animals. We finally identify a novel composition (CaMgSi(2)O(6):Eu(2+),Mn(2+),Pr(3+)) for in vivo imaging, displaying a strong near-infrared afterglow centered on 685 nm, and present evidence that intravenous injection of such persistent luminescence nanoparticles in mice allows not only improved but highly sensitive detection through living tissues.

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

“…For Mn 2+ , normal photo­emission occurs from the state 4 T 1 ( 4 G ) to the ground state 6 A 1 ( 6 S ). This transition depends strongly on the crystal field of the ligands, what is most visible in the characteristic distinction between green luminescence that is typically associated with a tetrahedral coordination environment, IV Mn 2+ (i.e., lower ligand field strength), and orange or red luminescence from octahedral VI Mn 2+ (i.e., stronger ligand field) 6, 7. Between those two species, the overall luminescence properties, in particular, emission color and quantum efficiency, can be tailored by controlling the precipitation of the Mn 2+ activator 8, 9, 10…”

Tailoring of the trap distribution and crystal field in Cr3+-doped non-gallate phosphors with near-infrared long-persistence phosphorescence

“…6 Such biomarkers are expected to enable advanced optical imaging with high-resolution and minimal excitation disturbance to experimentally assess structural and functional processes in cells, tissues and other complexes in in vivo systems. 7 Over the past few years, substantial strides have been made in the research and development of LPPs for NIR wavelengths, [8][9][10][11][12][13][14][15][16][17][18][19][20] with the main focus of the research being Mn 2+ , Mn 4+ and Cr 3+ -activated NIR LPPs. In 2007, Chermont et al proposed a novel bio-imaging method using red-to-NIR persistent nanoparticles, Ca 0.2 Zn 0.9 Mg 0.9 Si 2 O 6 : Eu 2+ , Dy 3+ , Mn 2+ , and opened a new application area for NIR LPPs.…”

“…In addition to ZnGa 2 O 4 : Cr 3+ , La 3 Ga 5 3+ , were investigated because of the excellent ability of Cr 3+ ions to substitute for Ga 3+ ions in distorted octahedral coordination. [9][10][11][12][13][14][15][16][17][18][19][20] The predominance of Cr 3+ -activated gallates might suggest that only gallates can be used as the hosts in Cr 3+ -doped NIR LPPs. Such a dependence would result in the trapping and de-trapping processes being closely associated with the crystalline structure or energy band structure, of gallates because a variety of defects in gallate materials, including antisite defects and Ga vacancies, have been proposed as an electron (or hole) reservoir to improve the afterglow properties.…”

“…Such a dependence would result in the trapping and de-trapping processes being closely associated with the crystalline structure or energy band structure, of gallates because a variety of defects in gallate materials, including antisite defects and Ga vacancies, have been proposed as an electron (or hole) reservoir to improve the afterglow properties. [7][8][9][10] However, it is challenging to identify the nature of defects and it is difficult to predict the actual effectiveness and impact of intrinsic and substituted defects in gallates because comparison with Cr 3+ -doped non-gallate phosphors is missing. To date, there have been no convincing proposals of an effective alternative system that might replace gallates as the preferred host for achieving super-long NIR afterglow emissions.…”

Innovative First Step toward Mechanoluminescent Ubiquitous Light Source for Trillion Sensors

“…(6,19,20) Furthermore, the size of ML nanoparticles, several tens of nanometers, is sufficiently small for injection against bio-body. (21,22) It can be expected that ML particles will act as ubiquitous light sources or ubiquitous energy harvesting systems for the Trillion Sensors Universe, which can be used anytime and anywhere even in the human body and deliver photons to photofunctional materials and trillion sensors existing inside the body for phototherapy, diagnosis, and imaging. (23)(24)(25) …”