Nanocomposite of Au and black phosphorus quantum dots as versatile probes for amphibious SERS spectroscopy, 3D photoacoustic imaging and cancer therapy

To expand the bioimaging applications of Au and black phosphorus, black phosphorus quantum dot-Au hybrids (Au-BPQD nanohybrids) are fabricated for multiple theranostic applications in this study. By simply varying the ratios of BPQDs and Au3+, the BPQDs assisted Au3+ reduction outputs two kinds of nanohybrids with different functions. The less BPQDs lead to small size Au-BPQD nanohybrids (S-ABPs) with a core-shell structure. S-ABPs exhibit superior near-infrared (NIR) surface-enhanced Raman scattering (SERS) activity for the fingerprint analysis of biomolecules. It's also very promising for interference-free bioimaging due to the distinctive Raman band at around 2190 cm−1 in the biologically Raman-silent region, which cannot be achieved by Au or BP-based nanomaterials. Meanwhile, further addition of BPQDs would lead to large size Au-BPQD nanohybrids (L-ABPs) with strong NIR optical absorption, which facilitates the in vivo 3D photoacoustic imaging as well as the photothermal therapy against tumor. This work reports versatile nanotheranostic platforms for amphibious SERS spectroscopy, 3D photoacoustic imaging and cancer therapy, which opens a new door for the biomedical applications of BP and Au based nanomaterials.