Fig. 5

Assessment of the thermal stability of HIDPPDNE-entrapped ICG and freely dissolved ICG in PBS. I a–d show the UV–Vis spectra of HIDPPDNEs (a, b) and freely dissolved ICG (c, d) in PBS under 4 (a, c) or 37 °C (b, d) incubation without light illumination for 0, 2, 4, 24, and 48 h. The absorbance at λ = 780 nm in each spectrum denotes the level of ICG remaining in the sample after the treatment. II The variation curves of ICG remaining in the HIDPPDNEs or in the PBS under 4 and 37 °C incubation for 48 h. Values are mean ± s.d. (n = 3)