Kinetically and thermodynamically controlled one-pot growth of gold nanoshells with NIR-II absorption for multimodal imaging-guided photothermal therapy.

Since the successful clinical trial of AuroShell for photothermal therapy, there is currently intense interest in developing gold-based core-shell structures with near-infrared (NIR) absorption ranging from NIR-I (650-900 nm) to NIR-II (900-1700 nm). Here, we propose a seed-mediated successive growth approach to produce gold nanoshells on the surface of the nanoscale metal-organic framework (NMOF) of UiO-66-NH2 (UiO = the University of Oslo) in one pot. The key to this strategy is to modulate the proportion of the formaldehyde (reductant) and its regulator / oxidative product of formic acid to harness the particle nucleation and growth rate within the same system. The gold nanoshells propagate through a well-oriented and controllable diffusion growth pattern (points → facets → octahedron), which has not been identified. Most strikingly, the gold nanoshells prepared hereby exhibit an exceedingly broad and strong absorption in NIR-II with a peak beyond 1300 nm and outstanding photothermal conversion efficiency of 74.0%. Owing to such superior performance, these gold nanoshells show promising outcomes in photoacoustic (PA), computed tomography (CT), and photothermal imaging-guided photothermal therapy (PTT) for breast cancer, as demonstrated both in vitro and in vivo.

Beyond the Roles in Biomimetic Chemistry: An Insight into the Intrinsic Catalytic Activity of an Enzyme for Tumor-Selective Phototheranostics.

Protein-assisted biomimetic synthesis has been an emerging offshoot of nanofabrication in recent years owing to its features of green chemistry, facile process, and ease of multi-integration. As a result, many proteins have been used for biomimetic synthesis of varying kinds of nanostructures. Although the efforts on exploring new proteins and investigating their roles in biomimetic chemistry are increasing, the most essential intrinsic properties of proteins are largely neglected. Herein we report a frequently used enzyme (horseradish peroxidase, HRP) to demonstrate the possibility of enzymatic activity retaining after accomplishing the roles in biomimetic synthesis of ultrasmall gadolinium (Gd) nanodots and stowing its substrate 2,2'-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS), denoted as Gd@HRPABTS. It was found that ca. 70% of the enzymatic activity of HRP was preserved. The associated changes of protein structure with chemical treatments were studied by spectroscopic analysis. Leveraging on the highly retained catalytic activity, Gd@HRPABTS exerts strong catalytic oxidation of peroxidase substrate ABTS into photoactive counterparts in the presence of intrinsic H2O2 inside the tumor, therefore enabling tumor-selective catalytic photoacoustic (PA) imaging and photothermal therapy (PTT). In addition, the MR moiety of Gd@HRPABTS provides guidance for PTT and further diagrams that Gd@HRPABTS is clearable from the body via kidneys. Preliminary toxicity studies show no observed adverse effects by administration of them. This study demonstrates beyond the well-known roles in biomimetic chemistry that HRP can also preserve its enzymatic activity for tumor catalytic theranostics.