Inorganic Chemistry
Communication
DPBF solution containing MTA-PPT NPs decreased sharply
showed bright red fluorescence when incubated with MTA-PPT
NPs, indicating MTA-PPT NPs can be swallowed efficiently.
Furthermore, the merged image red MTA-PPT NPs and blue
DAPI clearly showed that MTA-PPT NPs located in cytoplasm
around nucleus.
HeLa cells were selected to study the PDT effect of MTA-
PPT NPs in vitro. Their viability after a range of treatments was
measured by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-di-
phenyltetrazolium bromide (MTT) assays. First, HeLa cells
were administrated with PEG-PPT NPs, 1-PPT NPs, or MTA-
−
1
−2
PPT NPs (0−100 μg mL ) and then irradiated with 1 W cm
Figure 3. Time-dependent UV−vis spectra of DPBF (a) with and (b)
without MTA-PPT NPs in aqueous solution upon irradiation with 660
−
2
nm light (1 mW cm ) for various times (0−180 s). (c) Comparison of
A/A rate of DPBF solution with (red) and without (blue) MTA-PPT
0
NPs under irradiation. A is the initial absorbance, and A is the
0
immediate absorbance at 477 nm in (a) (DPBF + MTA-PPT NPs) and
1
(
b) (DPBF). (d)−(f) CLSM images of O formation in HeLa cells
2
after various incubation with DCFH-DA as the indicator.
oxygen. For comparison, the absorbance at 447 nm almost
remained unchanged when the DPBF solution had no MTA-
PPT NPs (Figure 3b). More obviously, the photodynamic
activity of MTA-PPT NPs upon laser irradiation was
demonstrated by the changes of the maximum absorption
peak (Figure 3c). The quantum yield of the generation of singlet
oxygen is about 0.50 with MB as the standard compound. Then,
Figure 5. (a) Viabilities of HeLa cells incubated with PEG-PPT NPs, 1-
PPT NPs, and MTA-PPT NPs without or with 660 nm laser. (b)−(g)
FL images of HeLa cells costained with Calcein AM (live cells, green)
and PI (dead cells, red) after various treatments. Scale bar: 20 μm. [c] =
the confocal laser scanning microscopy (CLSM) was employed
1
to study the intracellular O generation of MTA-PPT NPs in
2
10 μg/mL.
HeLa cells under 660 nm irradiation with DCFH-DA as the
1
1
probe. Here, the nonfluorescent DCFH-DA can be oxidized
1
into green fluorescent 2′,7′-dichloroflorescein (DCF) by O .
cytotoxicity was found for cells in PEG-PPT NPs and 1-PPT
NPs groups. Specific to MTA-PPT NPs and Pt-PPT NPs,
however, it exhibited moderate cytotoxicity due to the release of
the Pt drug under the low-pH cancer cell microenvironment.
However, the viabilities of the cells decreased sharply when the
concentrations of MTA-PPT NPs increased under irradiation,
while ligand 1-PPT nanoparticles with only PDT exhibited
lower cytotoxicity (Figure 5a). In order to visualize the PDT
effect of MTA-PPT NPs, we employed calcein−acetoxymethyl
(Calcein-AM) and propidium iodide (PI) staining to differ-
entiate dead (red) and live (green) cells (Figure 5b−g). HeLa
cells administrated with PEG-PPT NPs, 1-PPT NPs, or only
660 nm laser irradiation (laser) exhibited the bright green
fluorescence. Nevertheless, MTA-PPT NPs and 1-PPT NPs
with irradiation exhibited the both green and red fluorescence.
However, when incubated with MTA-PPT NPs and laser
irradiation (MTA-PPT NPs + laser), nearly all the cells showed
red fluorescence. All these results showed that MTA-PPT NPs
exhibited good efficiency for cancer therapies under the
irradiation with 660 nm laser.
2
Figure 3d clearly revealed that when HeLa cells administrated
with both MTA-PPT NPs and 660 nm laser irradiation (MTA-
PPT NPs + laser), bright green fluorescence was observed due
1
to the formation of O . On the other hand, no obvious
2
fluorescence was found in the cells administrated with MTA-
PPT NPs or 660 nm laser irradiation only (MTA-PPT NPs or
laser). All these results showed that MTA-PPT NPs can be used
as an ideal platform for photodynamic therapy.
In order to check whether MTA-PPT NPs possess effective
therapeutic effects, cellular uptake was employed. Here, we used
confocal laser scanning microscopy (CLSM) to study the
cellular uptake of MTA-PPT NPs by HeLa cells. First, cells were
administrated with MTA-PPT NPs for 2 h, then DAPI with blue
fluorescence was applied to stain the predetermined cells’
In conclusion, a porphyrin-based discrete organoplatinum(II)
metallatriangle (MTA) was fabricated by complying with the
reported strategy termed as “coordination driven self-assembly”.
3
1
1
P NMR, H NMR, HR-MS, and theoretical calculations were
used to characterize MTA fully. Furthermore, MTA could be
coassembled with a biocompatible polypeptide (PEG-PPT) to
fabricate nanoparticles (MTA-PPT NPs) that could generate
Figure 4. CLSM of HeLa cells incubated with MTA-PPT NPs and
DAPI Blue (0.005 mm) for 2 h. Scale bar: 20 μm.
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Inorg. Chem. 2021, 60, 7627−7631