No abstract

The imbalance between oxidants and antioxidants in cancer cells would evoke oxidative stress-induced cell death, which has been demonstrated to be highly effective in treating malignant tumors. Sonodynamic therapy (SDT) adopts ultrasound (US) as the excitation source to induce the production of reactive oxygen species (ROS), which emerges as a noninvasive therapeutic strategy with deep tissue penetration depth and high clinical safety. Herein, we construct novel sonoactivated oxidative stress amplification nanoplatforms by coating MnO 2 on Au nanoparticle-anchored black phosphorus nanosheets and decorating soybean phospholipid subsequently (Au/BP@MS). The Au/BP@MS exhibit increased ROS generation efficiency under US irradiation in tumor tissues due to Au/BP nanosensitizer-induced improvement of electron-hole separation as well as MnO 2 -mediated O 2 generation and GSH depletion, thus leading to notable inhibition effect on tumor growth. Moreover, tumor microenvironment-responsive biodegradability of Au/BP@MS endows them with enhanced magnetic resonance imaging guidance and clinical potential for cancer theranostics.

Until now, enormous smart materials have been engineered with endogenous stimulators such as pH, reactive oxygen species, glutathione, hypoxia and enzyme, or exogenous stimulators such as temperature, light, ultrasound, radiation, and magnetic field in drug delivery. As footstone of stimuli‐responsive nanocarriers, endogenous/exogenous responsive smart materials possess many properties, such as responding ability to specific triggers, controlled drug release, long blood circulation, increased tumor accumulation, “ON‐OFF” switch activities, enhanced diagnostic accuracy, and therapeutic efficacy. Smart materials have attracted considerable attention because they provide likelihood strategy for individualized and comprehensive therapy. In this review, significant research achievements of smart materials responsive to different triggers including their synthesis and formulation mechanism, responsive mechanism, applications, multiple functions are summarized and discussed separately. We primarily focus on the studies in the past few years (2017‐2020). The current situation and remaining challenges of stimuli‐sensitive materials‐based nanocarriers for clinical translation are discussed rationally at the end. It is hope that this timely and overall review would provide some helpful information for researchers in this field.

The critical issue that hinders the translation of nanomaterials from basic research to clinical trials is their potential toxicity caused by long‐term body retention. It is still a huge challenge to integrate renal‐clearable and theranostic properties into one nanomedicine, especially exploring the nanomaterials with optical absorption in the second near‐infrared light (NIR II) biowindow with deep penetration and less tissue scattering. Here, ultrasmall polypyrrole (PPy, ≈2 nm)‐based theranostic agents via a facile and green one‐step method, which exhibit fluorescence (FL)/photoacoustic (PA)/NIR II multimodal imaging, superior photostability, as well as high photothermal conversion efficiency of 33.35% at 808 nm and 41.97% at 1064 nm is developed. Importantly, these ultrasmall PPy‐PEG nanoparticles (NPs) reveal abundant tumor accumulation and efficient renal clearance. Both in vitro and in vivo studies indicate that ultrasmall PPy‐PEG NPs have excellent photothermal effect under NIR II laser irradiation that can effectively eliminate the tumors with extremely low systemic toxicity.

The immune system is involved in the initiation and progression of cancer. Research on cancer and immunity has contributed to the development of several clinically successful immunotherapies. These immunotherapies often act on a single step of the cancer–immunity cycle. In recent years, the discovery of new nanomaterials has dramatically expanded the functions and potential applications of nanomaterials. In addition to acting as drug-delivery platforms, some nanomaterials can induce the immunogenic cell death (ICD) of cancer cells or regulate the profile and strength of the immune response as immunomodulators. Based on their versatility, nanomaterials may serve as an integrated platform for multiple drugs or therapeutic strategies, simultaneously targeting several steps of the cancer–immunity cycle to enhance the outcome of anticancer immune response. To illustrate the critical roles of nanomaterials in cancer immunotherapies based on cancer–immunity cycle, this review will comprehensively describe the crosstalk between the immune system and cancer, and the current applications of nanomaterials, including drug carriers, ICD inducers, and immunomodulators. Moreover, this review will provide a detailed discussion of the knowledge regarding developing combinational cancer immunotherapies based on the cancer–immunity cycle, hoping to maximize the efficacy of these treatments assisted by nanomaterials.