Activatable NIR‐II Plasmonic Nanotheranostics for Efficient Photoacoustic Imaging and Photothermal Cancer Therapy

Abstract

Precise manipulation of optical properties through the structure‐evolution of plasmonic nanoparticles is of great interest in biomedical fields including bioimaging and phototherapy. However, previous success has been limited to fixed assembled structures or visible–NIR‐I absorption. Here, an activatable NIR‐II plasmonic theranostics system based on silica‐encapsulated self‐assembled gold nanochains (AuNCs@SiO2) for accurate tumor diagnosis and effective treatment is reported. This transformable chain structure breaks through the traditional molecular imaging window, whose absorption can be redshifted from the visible to the NIR‐II region owing to the fusion between adjacent gold nanoparticles in the restricted local space of AuNCs@SiO2 triggered by the high H2O2 level in the tumor microenvironment (TME), leading to the generation of a new string‐like structure with strong NIR‐II absorption, which is further confirmed by finite‐difference‐time‐domain (FDTD) simulation. With the TME‐activated characteristics, AuNCs@SiO2 exhibits excellent properties for photoacoustic imaging and a high photothermal conversion efficiency of 82.2% at 1064 nm leading to severe cell death and remarkable tumor growth inhibition in vivo. These prominent intelligent TME‐responsive features of AuNCs@SiO2 may open up a new avenue to explore optical regulated nano‐platform for intelligent, accurate, and noninvasive theranostics in NIR‐II window.

Recent advances in selective photothermal therapy of tumor

“…However, the excitation window of existing PTT is mainly located in the visible or NIR region, with insufficient penetration depth and relatively low interaction with tissues, limiting its thermal sensitivity effect. Therefore, Professor Zhang Dong et al [ 69 ] developed an activatable NIR-II plasmonic theranostics system based on silica-encapsulated, self-assembled, gold nanochains (AuNCs@SiO 2 ). In this study, the optical properties were precisely controlled by the structural changes of plasmonic nanoparticles in response to the tumor microenvironment, leading to accurate diagnosis and effective treatment of tumors.…”

Recent Advances in Functional Carbon Quantum Dots for Antitumour

“…In recent years, photothermal therapy (PTT) has attracted extensive research, which aims to use a photothermal conversion agent to absorb near-infrared light (650~900 nm) and convert the absorbed light energy into heat energy to further achieve the deep penetration of tissues and the minimum heating of nontarget tissues. [204][205][206] Therefore, the choice of photothermal agent is the key factor in determining the success of photothermal therapy. First, to obtain effective treatment results, near-infrared photothermal agent-mediated tumour treatment usually requires a near-infrared laser irradiation power density significantly less than the maximum allowable skin exposure.…”

Near-Infrared Inorganic Nanomaterials for Precise Diagnosis and Therapy

“…Meanwhile, binary or ternary metal nanomaterials can greatly expand the properties of metals. Researchers in material science have discovered that some metal nanomaterials not only demonstrate outstanding catalytic properties, but also have excellent optical properties (Wang S. et al, 2020;Li H. et al, 2020;Shu et al, 2020;Sun et al, 2021;Zhou et al, 2021). Different from traditional noble metal nanocrystals with unique optical properties dominated by surface plasmon resonance, the metal nanoclusters have strong quantum confinement effect with discrete energy band.…”