# PEG/Folic Acid Coloaded Er:Y2O3 Upconversion Nanoparticles: Enhanced Internalization and Potential for High-Contrast Bioimaging in HCT-116 Cells

## TL;DR

Researchers developed Er:Y2O3 nanoparticles with PEG and folic acid to target cancer cells and improve imaging contrast.

## Contribution

The study introduces PEG/folic acid coloaded Er:Y2O3 nanoparticles with enhanced internalization and bioimaging potential.

## Key findings

- PEG-FA nanoparticles showed low cytotoxicity in HCT-116 cells at concentrations up to 1 μg/mL.
- Folic acid enhanced nanoparticle internalization compared to PEG-only nanoparticles.
- NIR excitation at 980 nm reduced cellular autofluorescence, improving imaging contrast.

## Abstract

Erbium-doped yttrium oxide nanoparticles (Er:Y2O3 NPs) with a log-normal size distribution peaking at
43 nm
were synthesized and coloaded with PEG and folic acid (FA) to achieve
tumor cell targeting while maintaining good water dispersibility.
Structural and optical analyses (TEM, FTIR, PL, upconversion) confirmed
successful functionalization without significant alterations in the
fluorescence signal. In colorectal cancer cells (HCT-116), MTT assays
showed >80% viability for concentrations of NPs between 0.1 and
1
μg/mL, indicating low cytotoxicity. Confocal microscopy revealed
fluorescence signals consistent with potential nanoparticle internalization,
although contrast was limited by cellular autofluorescence. ICP-OES
quantification supported greater internalization of PEG-FA nanoparticles
compared to PEG nanoparticles, confirming the role of FA in enhancing
internalization. Moreover, NIR excitation (980 nm) suppressed cellular
autofluorescence, suggesting the potential of these nanoparticles
for high-contrast bioimaging applications.