Ultrathin Nanosheet-Supported Ag@Ag ₂O Core–Shell Nanoparticles with Vastly Enhanced Photothermal Conversion Efficiency for NIR-II-Triggered Photothermal Therapy

The development, perspectives, and challenges of photothermal therapy (PTT) and photoacoustic imaging (PAI) via nanotheranostics for combating cancer. The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.

Conventionally, ceramics-based materials, fabricated by high-temperature solid-phase reaction and sintering, are preferred as bone scaffolds in hard-tissue engineering because of their tunable biocompatibility and mechanical properties. However, their possible biomedical applications have rarely been considered, especially the cancer phototherapeutic applications in both the first and second near-infrared light (NIR-I and NIR-II) biowindows. In this work, we explore, for the first time as far as we know, a novel kind of 2D niobium carbide (Nb2C), MXene, with highly efficient in vivo photothermal ablation of mouse tumor xenografts in both NIR-I and NIR-II windows. The 2D Nb2C nanosheets (NSs) were fabricated by a facile and scalable two-step liquid exfoliation method combining stepwise delamination and intercalation procedures. The ultrathin, lateral-nanosized Nb2C NSs exhibited extraordinarily high photothermal conversion efficiency (36.4% at NIR-I and 45.65% at NIR-II), as well as high photothermal stability. The Nb2C NSs intrinsically feature unique enzyme-responsive biodegradability to human myeloperoxidase, low phototoxicity, and high biocompatibility. Especially, these surface-engineered Nb2C NSs present highly efficient in vivo photothermal ablation and eradication of tumor in both NIR-I and NIR-II biowindows. This work significantly broadens the application prospects of 2D MXenes by rationally designing their compositions and exploring related physiochemical properties, especially on phototherapy of cancer.

Gold nanorods have been receiving extensive attention owing to their extremely attractive applications in biomedical technologies, plasmon-enhanced spectroscopies, and optical and optoelectronic devices. The growth methods and plasmonic properties of Au nanorods have therefore been intensively studied. In this review, we present a comprehensive overview of the flourishing field of Au nanorods in the past five years. We will focus mainly on the approaches for the growth, shape and size tuning, functionalization, and assembly of Au nanorods, as well as the methods for the preparation of their hybrid structures. The plasmonic properties and the associated applications of Au nanorods will also be discussed in detail.