Figure 3. Biodegradation performance.

(a) Absorbance spectra of the BPQDs/PLGA NSs (internal BPQDs concentration is 10 p.p.m.) dispersed in PBS for 0 h, 24 h and 8 weeks with the inset showing the corresponding photographs. (b) Photothermal heating curves of the BPQDs/PLGA NSs dispersed in PBS for 0 h, 24 h and 8 weeks and irradiated with the 808 nm laser (1 W cm⁻²) for 10 min. (c) Residual weight of the BPQDs/PLGA NSs after degradation in PBS as a function of time (n=5; ^*P<0.05, ^**P<0.01, ^***P<0.001; ANOVA). (d) SEM images (scale bars, 500 nm) of the BPQDs/PLGA NSs after degradation in PBS for 1, 4 and 8 weeks together with the corresponding TEM image (scale bar, 200 nm) of the NSs after degradation for 8 weeks. (e) Schematic representation of the degradation process of the BPQDs/PLGA NSs in the physiological environment.