A Highly Effective π–π Stacking Strategy To Modify Black Phosphorus with Aromatic Molecules for Cancer Theranostics

Even though black phosphorus (BP) has exhibited outstanding capabilities in biomedical, physical, and energy fields, the issues of degradation under ambient conditions and unreactive functional interface limit its further application. There are numerous methodologies utilized to prevent BP degradation; however, these methods usually generate further problems and normally do not involve alterations to the chemically inert BP. Herein, for the first time, we propose a simple and efficient strategy to prepare and modify BP nanosheets (p-BPNSs) by employing aromatic 1-pyrenylbutyric acid through a noncovalent π–π stacking interaction. This strategy not only adopts a novel strategy for enhancing the stability of BPNSs but also paves a convenient way to anchor other active biomolecules such as a targeting effect to extend the biomedical applications of BPNSs. The modified p-BPNSs exhibit enhanced physical and chemical stabilities as well as rich carboxyl groups for further modification. In this work, RGD-modified p-BPNSs exhibit targeted photothermal therapy ability against cancer in both in vitro and in vivo studies, owing to anchoring of arginine-glycine-aspartic acid (RGD) tripeptides, which could target nanosheets into the tumor site through systematic circulation. Consequently, this work not only provides a new concept for modifying and protecting the BP but also opens a novel window for extending the biomedical application of BP by surface engineering.