Photoacoustic Imaging and Photothermal Therapy of Semiconducting Polymer Nanoparticles: Signal Amplification and Second Near‐Infrared Construction

Abstract

Photoacoustic (PA) imaging and photothermal therapy (PTT) have attracted extensive attention in disease diagnosis and treatment. Although many exogenous contrast agents have been developed for PA imaging and PTT, the design guidelines to amplify their imaging and therapy performances remain challenging and are highly demanded. Semiconducting polymer nanoparticles (SPNs) composed of polymers with π‐electron delocalized backbones can be designed to amplify their PA imaging and PTT performance, because of their clear structure–property relation and versatility in modifying their molecular structures to tune their photophysical properties. This review summarizes the recent advances in the photoacoustic imaging and photothermal therapy applications of semiconducting polymer nanoparticles with a focus on signal amplification and second near‐infrared (NIR‐II, 1000–1700 nm) construction. The strategies such as structure–property screening, fluorescence quenching, accelerated heat dissipation, and size‐dependent heat dissipation are first discussed to amplify the PA brightness of SPNs for in vivo PA. The molecular approaches to shifting the absorption of SPNs for NIR‐II PA imaging and PTT are then introduced so as to improve the tissue penetration depth for diagnosis and therapy. At last, current challenges and perspectives of SPNs in the field of imaging and therapy are discussed.

Co-delivery of nanoparticle and molecular drug by hollow mesoporous organosilica for tumor-activated and photothermal-augmented chemotherapy of breast cancer

“…Drug delivery nanosystems have been employed for efficient cancer diagnosis and treatment, particularly since the significant development of nanobiotechnology applications [ 1 – 8 ]. These organic and inorganic nanoplatforms are multifunctional, have excellent biocompatibility, have relatively high stability in bodily fluids, and have the capacity for the controlled release of therapeutic agents from the nanocarriers in the desired sites, particularly toward tumor cells [ 9 – 18 ]. In particular, biocompatible organic–inorganic hybrid hollow mesoporous organosilica nanoparticles (HMONs) have shown high performance in molecular imaging and drug delivery as compared with other inorganic nanosystems [ 19 – 24 ].…”

Multimodal Contrast Agents for Optoacoustic Brain Imaging in Small Animals

“…The NPs utilized for OA imaging are mainly carbon-based NPs, for example, single-walled carbon nanotubes; metal-based NPs, for example, gold NPs; bismuth-based NPs; polymer-encapsulated organic NPs; semiconducting polymer NPs (SPNs); conjugated polymer; and novel DNA-based nanocarriers. ( Pu et al, 2014 ; Li and Chen, 2015 ; Weber et al, 2016 ; Yang et al, 2018 ; Yu et al, 2019 ; Zhan et al, 2019 ; Xu et al, 2020 ; Cheng et al, 2021 ; Fan et al, 2021 ; Joseph et al, 2021 ; Qi et al, 2021a ; Tuo et al, 2021 ; Wang et al, 2021a ; Wang et al, 2021b ; Zhen et al, 2021 ). NPs have the advantage of versatile multimodal imaging capacity, a favorable signal/noise ratio, high photothermal conversion, deep penetration depth with near-infrared (NIR) II probes, and diverse structure and types (activable, turnable, and metabolizable).…”

“…Different types of exogenous contrast agents have been developed, including synthetic (chemical dyes or nanoparticles (NPs)), semi-genetic, and genetic contrast agents (e.g., genetically encoded calcium indicators and reversibly switchable OA proteins (Roberts et al, 2018;Qian et al, 2019;Mishra et al, 2020;Farhadi et al, 2021;Qu et al, 2021;Shemetov et al, 2021)). The criteria for contrast agent applied in OA brain imaging include a suitable absorbance spectrum (>600 nm wavelength) to allow unmixing with endogenous signals (e.g., Hb/HbO and melanin) and sufficient brain penetration depth, high affinity and specific binding to the target, sufficient blood-brain barrier entrance, photostability, solubility, low toxicity, high thermodynamics for MRI probes, and optimal pharmacokinetics (Weber et al, 2016 (Pu et al, 2014;Li and Chen, 2015;Weber et al, 2016;Yang et al, 2018;Yu et al, 2019;Zhan et al, 2019;Xu et al, 2020;Cheng et al, 2021;Fan et al, 2021;Joseph et al, 2021;Qi et al, 2021a;Tuo et al, 2021;Wang et al, 2021a;Wang et al, 2021b;Zhen et al, 2021). NPs have the advantage of versatile multimodal imaging capacity, a favorable signal/noise ratio, high photothermal conversion, deep penetration depth with nearinfrared (NIR) II probes, and diverse structure and types (activable, turnable, and metabolizable).…”

Emerging Designs of Aggregation-Induced Emission Agents for Enhanced Phototherapy Applications

“…Phototherapy that utilizes photoirradiation to generate cytotoxic reactive oxygen species (ROS) for photodynamic therapy (PDT) or hyperthermia for photothermal therapy (PTT) is a promising approach for disease therapy because of its non-invasiveness, negligible drug resistance, high therapeutic selectivity and efficacy, and minimized off-target side effects. [1][2][3][4][5][6][7] Organic contrast agents have attracted much attention in the phototherapy field due to their excellent optical properties and tunable molecular structures. [8][9][10][11] However, the traditional small molecular organic contrast agents used for phototherapy such as rose bengal analogs, methylene blue, and cyanine derivatives, suffer from poor photostability and aggregation-caused quenching (ACQ) in the aggregate state after they are transformed into water-soluble nanoparticles, leading to a relatively low therapeutic efficacy.…”