2 research outputs found
Methacrylated Cellulose Nanocrystals as Fillers for the Development of Photo-Cross-Linkable Cytocompatible Biosourced Formulations Targeting 3D Printing
Cellulose
nanocrystals (CNCs) from cotton were functionalized in
aqueous medium using methacrylic anhydride (MA) to produce methacrylated
cellulose nanocrystals (mCNCs) with a degree of methacrylation (DM)
up to 12.6 ± 0.50%. Dispersible as-prepared CNCs and mCNCs were
then considered as reinforcing fillers for aqueous 3D-printable formulations
based on methacrylated carboxymethylcellulose (mCMC). The rheological
properties of such photo-cross-linkable aqueous formulations containing
nonmodified CNCs or mCNCs at 0.2 or 0.5 wt% in 2 wt% mCMC were fully
investigated. The influence of the presence of nanoparticles on the
UV-curing kinetics and dimensions of the photo-cross-linked hydrogels
was probed and 13C CP-MAS NMR spectroscopy was used to
determine the maximum conversion ratio of methacrylates as well as
the optimized time required for UV postcuring. The viscoelasticity
of cross-linked hydrogels and swollen hydrogels was also studied.
The addition of 0.5 wt% mCNC with a DM of 0.83 ± 0.040% to the
formulation yielded faster cross-linking kinetics, better resolution,
more robust cross-linked hydrogels, and more stable swollen hydrogels
than pure mCMC materials. Additionally, the produced cryogels showed
no cytotoxicity toward L929 fibroblasts. This biobased formulation
could thus be considered for the 3D printing of hydrogels dedicated
to biomedical purposes using vat polymerization techniques, such as
stereolithography or digital light processing
FRET Imaging Approaches for <i>in Vitro</i> and <i>in Vivo</i> Characterization of Synthetic Lipid Nanoparticles
DiI
and DiD, two fluorophores able to interact by FRET (Förster
resonance energy transfer), were coencapsulated in the core of lipid
nanocapsules (LNCs) and nanoemulsions (LNEs), lipophilic reservoirs
for the delivery of drugs. The ability of FRET imaging to provide
information on the kinetics of dissociation of the nanoparticles in
the presence of bovine serum albumin (BSA) or whole serum, or after
incubation with cancer cells, and after systemic administration in
tumor-bearing mice, was studied. Both microscopic and macroscopic
imaging was performed to determine the behavior of the nanostructures
in a biological environment. When 2 mg/mL FRET LNEs or LNCs were dispersed
in buffer, in the presence of unloaded nanoparticles, BSA, or in whole
serum, the presence of serum was the most active in destroying the
particles. This occurred immediately with a diminution of 20% of FRET,
then slowly, ending up with still 30% intact nanoparticles at 24 h.
LNCs were internalized rapidly in cultured cells with the FRET signal
decreasing within the first minutes of incubation, and then a plateau
was reached and LNCs remained intact during 3 h. In contrast, LNEs
were poorly internalized and were rapidly dissociated after internalization.
Following their iv injection, LNCs appeared very stable in subcutaneous
tumors implanted in mice. Intact particles were found using microscopic
FRET determination on tumor sections 24 h after injection, that correlated
well with the 8% calculated noninvasively on live animals. FRET investigations
showed the potential to determine valid and reliable information about <i>in vitro</i> and <i>in vivo</i> behavior of nanoparticles