Figure 2. Stability evaluation under ambient conditions.

(a) Photographs and (b,c) Absorption spectra of the BPQDs and BPQDs/PLGA NSs with the same amount of BPQDs (20 p.p.m.) after storing in water for different periods of time. Insets in (b,c): tyndall effect and variation of the absorption ratios (A/A₀) at 808 nm. (d,e) Raman scattering spectra acquired from the BPQDs and BPQDs/PLGA NSs, respectively, after storing in water for 0 and 8 days. (f,g) Photothermal heating curves of the BPQDs and BPQDs/PLGA NSs, respectively, after storing in water for different periods of time and being irradiated with the 808 nm laser (1 W cm⁻²) for 10 min.