To develop a novel type of nanoparticle for cancer therapy, gold nanorods (GNRs) are coated with chitosan (CS) derivatives to combine chemical and photothermal effects. Thiol-modified chitosan derivatives chemically conjugated to doxorubicin (DOX) are successfully synthesized and their in vitro effect is evaluated. Functional nanocarriers (DOX-CS-GNR) with good biocompatibility and optical properties are prepared by conjugating chitosan derivatives to GNRs. Two types of structures with different molar ratios of chitosan derivatives and GNRs are successfully obtained. In in vitro studies, GNR-loaded nanoparticles show low cytotoxicity and high potential for anti-cancer effects. Under conditions of short exposure time and low light intensity, DOX-CS-GNR nanocarriers with a side-by-side structure exhibit cytoxicity against tumor cells based on a combination of chemical and photothermal therapeutic effects.
Biocompatible,
near-infrared luminescent gold nanoclusters were
synthesized in situ using as-prepared chitosan grafted with N-acetyl-l-cysteine (NAC-CS). The fluorescent gold nanoclusters coated
with chitosan-N-acetyl-l-cysteine (AuNCs@NAC-CS) were aggregated
by multiple ultrasmall gold nanoclusters closing with each other,
with strong fluorescence emission at 680 nm upon excitation at 360
nm. AuNCs@NAC-CS did not display any appreciable cytotoxicity on cells
even at a concentration of 1.0 mg mL–1. AuNCs@NAC-CS
were more insensitive to H2O2 and trypsin compared
with fluorescent gold nanoclusters coated with Albumin Bovine V (AuNCs@BSA),
which make them have long time imaging in HeLa cells. Furthermore,
the obvious fluorescence signal of AuNCs@NAC-CS appeared in the liver
and kidney of the normal mice after 6 h injection. And the fluorescence
intensity decreased after that because of the highly efficient clearance
characteristics of ultrasmall nanoparticles. These findings demonstrated
that AuNCs@NAC-CS possessed good fluorescence, low cytotoxicity, and
low sensitivity to some content of cells, allowing imaging of the
living cells.
Poly(l-lactide-co-caprolactone) (PLCL,
50:50) has been used in cartilage tissue engineering because of its
high elasticity. However, its mechanical properties, including its
rigidity and viscoelasticity, must be improved for compatibility with
native cartilage. In this study, a set of PLCL/poly(l-lactic
acid) (PLLA) blends was prepared by blending with different mass ratios
of PLLA that range from 10 to 50%, using thermoplastic techniques.
After testing the properties of these PLCL/PLLA blends, they were
used to fabricate scaffolds by the 3D printing technology. The structures
and viscoelastic behavior of the PLCL/PLLA scaffolds were determined,
and then, the potential application of the scaffolds in cartilage
tissue engineering was evaluated by chondrocytes culture. All blends
demonstrate good thermal stability for the 3D printing technology.
All blends show good toughness, while the rigidity of PLCL is increased
through PLLA blending, and Young’s modulus of blends with 10–20%
PLLA is similar to that of native cartilage. Furthermore, blending
with PLLA improves the processability of PLCL for 3D printing, and
the compression modulus and viscoelasticity of 3D-printed PLCL/PLLA
scaffolds are different from that of PLCL. Additionally, the stress
relaxation time (t
1/2) of the PLCL/PLLA
scaffolds, which is important for chondrogenesis, is dramatically
shortened compared with the pure PLCL scaffold at the same 3D-printing
filling rate. Consistently, the PLCL90PLLA10 scaffold at a 70% filling
rate with much shorter t
1/2 is more conducive
to the proliferation and chondrogenesis of in vitro seeded chondrocytes accompanied by upregulated expression of SOX9
than the PLCL scaffold. Taken together, these results demonstrate
that blending with PLLA improves the printability of PLCL and enhances
its potential application, particularly PLCL/PLLA scaffolds with a
low ratio of PLLA, in cartilage tissue engineering.
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