Abstract There is considerable interest in
developing diagnostic nanotools for early detection and delivery of
various therapeutic agents for treatment of neurodegenerative diseases.
However, a key challenge remains in the selection of suitable surfaces
to overcome the nano–bio interface issue, namely that many
nanoparticle surfaces demonstrate instability when administered into
biological environments and show substantial cytotoxicity to the
central nervous system. In this study, we fabricated an evaluation
platform for bio–nano surface selection based on the combination of
upconversion nanoparticles (UCNPs), cultured neural cells and zebra
fish, and systemically demonstrated how it can evaluate the suitability
of nanoparticle surfaces for applications in the central nervous
system. Firstly, we fabricated highly lanthanidedoped UCNPs, which
generate the strongest tissue penetrable emission at 800 nm. We then
functionalized these UCNPs with four popular surfaces for evaluation.
Next, we systematically evaluated the spectral emission properties,
biophysical stability, cytotoxicity and cell uptake capability of these
surface-functionalized UCNPs in biological solutions or with cultured
NSC-34 cells. Through these studies, PEG-COOH proved to be the superior
surface modification. Accordingly, we further confirmed the
bioavailability of unmodified and surface modified UCNPs in the spinal
cord of living zebrafish. As predicted, PEG-UCNPs displayed excellent
dispersal and uptake into spinal motor neurons in living zebrafish.
Collectively, this study developed a versatile upconversion platform
for systematic evaluation of nanoparticle surfaces, which can provide
valuable information via systemic surface evaluation in vitro and in
vivo for future construction of multifunctional nanosystems for
theranostic applications in neurodegenerative diseases. A.pdf
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