Fig. 1. Synthesis of AuNCs by using (a) polymers^[15], (b) DNA^[16], (c) thiol molecules^[17] and (d) proteins^[18] as templates

Fig. 2. Methods to improve the quantum yield of AuNCs: (a) Alloy doping in Au core^[23]; (b) Surface ligand engineering^[26]; (c), (d) Aggregation-induced emission and AuNCs-based self-assemblies^[28-29]

Fig. 3. (a) Investigating the endocytosis of AuNCs by fluorescence imaging^[33]; (b) Scheme of modification of folic acid on the surface of AuNCs^[38]; (c) Differences in cellular uptake of unmodified AuNCs (SG) and folic acid-modified AuNCs (FA) in cells with different receptor expression levels by flow cytometry^[38]

Fig. 4. AuNCs as fluorescence probes for (a) cellular imaging of mitochondria and (b) investigating temperature of mitochondria in different regions within a cell through fluorescence lifetime imaging^[43]

Fig. 5. Fluorescent AuNCs for (a) fluorescence lifetime imaging^[44], (b) multi-photon fluorescence imaging^[47], (c) STED imaging^[48] and (d) super-resolution radial fluctuations imaging^[49]

Fig. 6. AuNCs with NIR-II emission for fluorescence imaging of (a) gastrointestinal^[53], (b) bone^[54], (c) renal metabolism^[55] and (d) blood vessel in vivo^[56]

Fig. 7. (a) In vivo ratiometric fluorescence sensing of hydrogen sulfide by using NIR-II fluorescent AuNCs combined with Ln nanoparticles^[57]; (b) NIR-II fluorescent AuNCs doped with Gd for MRI and NIR-II dual mode imaging^[58]