Crosslinked albumin–manganese nanoaggregates with sensitized T ₁ relaxivity and indocyanine green loading for multimodal imaging and cancer phototherapy

Abstract

An aggregation and crosslinking strategy is proposed for constructing high-relaxivity C-BM. The further increased r ₁, stabler FL, stronger PA and better PT effect are achieved in C-BM/I, which can be used for MR, NIR-II FL and PA imaging and PTT-PDT.

Abstract

Albumin–manganese-based nanocomposites (AMNs) characterized by simple preparation and good biocompatibility have been widely used for in vivo T ₁-weighted magnetic resonance imaging (MRI) and cancer theranostics. Herein, an aggregation and crosslinking assembly strategy was proposed to achieve the sensitization to T ₁ relaxivity of the albumin–manganese nanocomposite. At a relatively low Mn content (0.35%), the aggregation and crosslinking of bovine serum albumin–MnO ₂ (BM) resulted in a dramatic increase of T ₁ relaxivity from 5.49 to 67.2 mM ⁻¹ s ⁻¹. Upon the loading of indocyanine green (ICG) into the crosslinked BM nanoaggregates (C-BM), the T ₁ relaxivity of the C-BM/ICG nanocomposite (C-BM/I) was further increased to 97.3 mM ⁻¹ s ⁻¹, which was much higher than those reported previously even at high Mn contents. Moreover, the presence of C-BM greatly enhanced the photoacoustic (PA) and photothermal effects of ICG at 830 and 808 nm, respectively, and the second near infrared fluorescence (NIR-II FL) of ICG also showed better stability. Therefore, the synthesized C-BM/ICG nanocomposite exhibited remarkable performance in in vivo multimodal imaging of tumors, such as T ₁-weighted MRI, NIR-II FL imaging and PA imaging, and cancer phototherapy with little side effects. This work provided a highly efficient and promising multifunctional nanoprobe for breaking through the limits of cancer theranostics, and opened a new avenue for the development of high-relaxivity AMNs and multimodal imaging methodology.