Synthesis of NaGdF₄:Er³⁺/Yb³⁺ Upconversion Particles as Exogenous Contrast Agent for Swept-Source Optical Coherence Tomography: In Vitro Animal Tissue Imaging

Abstract

Swept-source optical coherence tomography (SSOCT) is a noncontact, noninvasive bioimaging tool that uses various probes to obtain high contrast images. Rare-earth based upconversion particles (UCPs) provide a unique platform to enhance the capabilities of bioimaging techniques. The UCPs can act as contrast enhancers for the SSOCT with additional optical functionality, and hence in this work upconversion emission optimized polyvinylpyrrolidone (PVP)/NaGdF4:Er3+/Yb3+ UCPs were synthesized and then injected into chicken breast tissues to enhance the SSOCT images. As-synthesized samples have shown good biocompatibility toward HEK293, HeLa cell lines and showed apparent enhancement in contrast to SSOCT images. Additionally, compared to the bare NaGdF4:Er3+/Yb3+ UCPs the polyvinylpyrrolidone-stabilized UCPs have shown 3-fold enhancement in the frequency of upconverted green and red light intensity under 976 nm diode laser excitation (26 W/cm2).

Synthesis, Neutron Diffraction, and DFT Studies of NaLa(WO4)2: Yb3+/Er3+; NIR Induced Green Fluorescent Bifunctional Probes for In Vitro Cell Imaging and Solid State Lighting

“…It has been reported that “n” deviates as the competition between linear decay and the UC process increases [10a] hence for the two‐photon process n=/∼2 and “n” becomes equal to or <1 for the single‐photon process. As shown in Figure S13a,b, the number of photons involved in the green and red emissions of the UCB and UCN are found to be 1.42, 0.85, and 1.32, 0.83 respectively which are in agreement with the literature [1e,10a,24] . Yet, the negligible variation of “n” among both the materials indicates a similar chemical environment of Er 3+ , Yb 3+, and their statistical distribution in the lattice.…”

Synthesis of NaYF4:Ho3+/Yb3+ colloidal upconversion phosphor and its application for OCT-based imaging, temperature sensing, fingerprinting and security ink

“…The bands present at 733 cm À1 , 2856 cm À1 , and 2928 cm À1 can be assigned to the rocking vibration and the symmetric and asymmetric stretching of the CH 2 molecule of oleic acid, respectively. 25,29 This confirms the coating of oleic acid on the surface of the UCNPs. The band present at 1119 cm À1 is due to the C-O stretching of an alcohol group like ethanol.…”

“…23 Mohan et al synthesized NaYF 4 :Ho 3+ /Yb 3+ phosphors and reported contrast enhancement in OCT-based imaging, but since the particle size was larger and agglomerated due to the synthesis method adopted, the particles were not able to diffuse efficiently into the cell; hence the contrast and depth resolution were limited. 24 In our previous reports, UCNPs were studied as a contrast enhancer for OCT. 25,26 Maurya et al 25 for the first time showed that an NaGdF 4 :Er 3+ /Yb 3+ upconversion phosphor has the capacity to enhance OCT image contrast through enhanced scattering of OCT scanning radiation by excited phosphor particles. The upconversion sample they prepared was not well dispersible in liquid media due to the synthesis methodology adopted.…”

“…There are several benefits of using a fluoride-based material over their oxide and phosphate counterparts for upconversion and they have been explored by various researchers. 21,25 In the present study NaYF 4 :Ho 3+ /Yb 3+ colloidal UCNPs are synthesized by a thermal decomposition route using oleic acid and octadecane as the reaction medium. The OCT and PTOCT measurements were performed on chicken breast tissue.…”

Cyanine dye-assembled composite upconversion nanoparticles for the sensing and cell imaging of nitrite based on a single particle imaging method

“…15 Notably, lanthanide-doped UCNPs have certain significant advantages, including high chemical stability, good photostability, zero autofluorescence background and low toxicity. [16][17][18] Based on this, UCNPs have become an efficient candidate in the analysis of biological and environmental samples, especially for luminescence imaging. [19][20][21] Total internal reflection (TIR) imaging technology could use an evanescent wave to excite fluorescent molecules in the range of hundreds of nanometers on the sample surface, 22,23 and is emerging as an extremely powerful tool used in single particle imaging.…”