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. Author manuscript; available in PMC: 2021 Apr 26.
Published in final edited form as: ACS Appl Bio Mater. 2019 Jul 4;2(8):3203–3211. doi: 10.1021/acsabm.9b00133

Figure 2.

Figure 2.

In vitro degradation of CuS-PEG nanoparticles. TEM images show CuS-PEG nanoparticles before incubation (a) and after 7-day incubation in water (pH 5) at 4 ºC (b) and 37 ºC (c). Thermosensitive degradation profiles were compared over 7-day incubation at pH 3 (d), pH 5 (e), and pH 7.4 (f) or at 4 ºC (g) and 37 ºC (h) (n = 3). (i) Thermosensitive degradation was confirmed by ICP-OES, which showed significantly different Cu concentrations in the retained CuS-PEG nanoparticles between the 4 ºC and 37 ºC groups, after ultracentrifugation with 30,000 kDa filter (n = 3). The degradation mechanism was validated by XPS of CuS-PEG nanoparticles after 7-day incubation in water (pH 5) at 4 ºC (j) and 37 ºC (k).