Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Metal Ion-Based Supramolecular Self-Assembly for Cancer Theranostics

Metal-ion-based self-assembly supramolecular theranostics exhibit excellent performance in biomedical applications owing to their potential superiorities for simultaneous precise diagnosis, targeted drug delivery, and monitoring the response to therapy in real-time. Specially, the rational designed systems could achieve specific in vivo self-assembly through complexation or ionic interaction to improve tissue-specific accumulation, penetration, and cell internalization, thereby reducing toxicities of drugs in diagnostics and therapy. Furthermore, such imaging traceable nanosystems could provide real-timely information of drug accumulation and therapeutic effects in a non-invasive and safe manner. Herein, the article highlights the recent prominent applications based on the metal ions self-assembly in cancer treatment. This strategy may open up new research directions to develop novel drug delivery systems for cancer theranostics.

Tumor Receptor-Mediated In Vivo Modulation of the Morphology, Phototherapeutic Properties, and Pharmacokinetics of Smart Nanomaterials

To be clinically efficacious, nanotherapeutic drugs need to reach disease tissues reliably and cause limited side effects to normal organs and tissues. Here, we report a proof-of-concept study on the development of a smart peptidic nanophototherapeutic agent in line with clinical requirements, which can transform its morphology from nanoparticles to nanofibrils at the tumor sites. This in vivo receptor-mediated transformation process resulted in the formation and prolonged tumor-retention of highly ordered (J-aggregate type of photosensitizer) photosensitive peptide nanofibrillar network with greatly enhanced photothermal and photodynamic properties. This strategy of "multiple daily low-intensity laser radiation after each intravenous injection of significantly low-dose of nanomaterials" demonstrated effective elimination of 4T1 orthotopic syngeneic breast cancer in mice. The technology for nanomaterial modulation based on living cell surface receptors, in this case tumor-associated α₃β₁ integrin, has great potential for clinical translation and is expected to improve the therapeutic efficacy against many cancers.

Acid-Induced In Vivo Assembly of Gold Nanoparticles for Enhanced Photoacoustic Imaging-Guided Photothermal Therapy of Tumors

The complexity of biological systems poses a great challenge in the development of nanotheranostic agents with enhanced therapeutic efficacies. To systematically overcome a series of barriers during in vivo administration and achieve optimal antitumor activity, nanotheranostic agents that can self-adaptively change their properties in response to certain tumor-associated signals are highly preferable. Herein, gold nanoparticles with a mixed-charge zwitterionic surface (Au-MUA-TMA) is fabricated, which can undergo pH-triggered self-assembly for promoting tumor targeting and improving photoacoustic imaging (PAI)-guided photothermal tumor ablation. In blood and normal tissues, relatively small-sized Au-MUA-TMA can circulate stably, and upon arriving at the tumor sites, they quickly assemble into larger aggregates in an acidic tumor environment to ensure higher tumor accumulation and retention. Furthermore, the absorption band of Au-MUA-TMA can be remarkably shifted to the near-infrared (NIR) region, which effectively activates the photoacoustic (PA) signals of tumors and enhances photothermal therapy (PTT) with minimal side effects. This in vivo self-assembly strategy enables the nanotheranostic agents to better fulfill multiple requirements for in vivo application, thereby attaining advanced performances in cancer diagnosis and treatment.