Polypeptide-Functionalized NaYF₄:Yb³⁺,Er³⁺ Nanoparticles: Red-Emission Biomarkers for High Quality Bioimaging Using a 915 nm Laser

Abstract

We prepared poly-L-aspartic acid (PASP) functionalized NaYF4:Yb(3+),Er(3+) upconversion nanoparticles (UCNP-PASP). These nanoparticles can give red upconversion emission under excitation at 915 nm, whose wavelength of emission and excitation is located in the optical window of biological tissue. Dynamic laser scatting and zeta potentials of UCNP-PASP were used to study their stabilities in different aqueous solution. To understand the mechanism of the red emission of UCNP-PASP, photoluminescence spectra of samples were recorded before and after modification with PASP, poly acrylic acid (PAA), and poly(ether imide) (PEI) ligands under excitation at 915 and 980 nm, respectively. The cytotoxicity of the UCNP-PASP was also examined on a A549 cell and KB cell by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. Moreover, the PASP-functionalized UCNP was employed as a potential biomarker for in vitro and in vivo experiments of upconversion luminescence imaging.

Nanoscale mapping of ZnO–TiO2 up-conversion phosphor containing Yb3+ and Er3+

“…Up-conversion (UC) phosphor provides visible-light emission at a low excitation energy through a multi-step excitation process [1]. In particular, the UC of near infrared (NIR) light to visible-light emissions is considered appropriate for solar cell [2][3][4][5][6] and biomarker [7][8][9][10][11] applications. In recent years, the materials and technology required for the synthesis of UC phosphors have attracted considerable attention.…”

Efficiency improvement of up-conversion process of plasmonic-enhanced Er-doped-NaYF4 nanoparticles under IR excitation

“…Optical up-conversion process has been studied over the last two decades to convert lowphoton optical signal such as infra red (IR) to higher photon energies such as visible light. This conversion is applied in wide variety of applications such as optical sensors, energy harvesting, medical treatment, and bioimaging [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Rare earth tri-valent lanthanide ions are extensively used as optical up-conversion materials.…”

The Effect of Hydrothermal Treatment on the Morphologies and Optical Properties of Upconversion NaYF4:Ln3+ Crystals

“…There are a wide number of reports that describe syntheses of inorganic crystals via coprecipitation, solvo/hydrothermal, microwave and thermal decomposition routes. [8][9][10][11] NaYF 4 may crystallize as cubic (α) or hexagonal (β) structures. However, a mixture of the α-and β-phases can be produced depending on the synthetic route.…”