Photocatalytic antibacterial approach shows great potential in treating multidrug-resistant bacterial infections. However, the bactericidal efficiency heavily depends on the photocatalytic activity of semiconductor materials, which is limited by the fast recombination of photogenerated electron–hole pairs. Janus nano-heterostructures with spatial control growth of TiO₂ nanoparticles (NPs) at one end of gold nanorods (Au NRs) are designed via surface ligand regulation for photocatalytic sterilization and infected wound healing. The asymmetric nanostructure of Janus gold nanorod-titanium dioxide nanoparticles (Janus AuNR-TiO₂ NPs) promotes the directional migration of charge carriers and is more conducive to the spatial separation of electron–hole pairs. Moreover, the injection of hot electrons and enhancement of plasmon near-fields from the surface plasmon resonance (SPR) effect further improve the photocatalytic efficiency of Janus AuNR-TiO₂ NPs. Under simulated sunlight irradiation, large amounts of reactive oxygen species (ROS) are generated for photocatalytic antibacterial activity. Enhanced bactericidal efficiency up to 99.99% against methicillin-resistant Staphylococcus aureus (MRSA) is achieved in vitro. Furthermore, Janus AuNR-TiO₂ NPs exhibit superior biocompatibility, structural stability, and also remarkably accelerate MRSA-infected wound healing. Taking the above all into consideration, Janus AuNR-TiO₂ NPs, as an efficient antibacterial photocatalyst, offers a promising strategy for MRSA infectious therapy.

Radiotherapy (RT) based on X-ray irradiation is a widely applied cancer treatment strategy in the clinic. However, treating cancer based on RT alone usually results in insufficient radiation energy deposition, which inevitably has serious side effects on healthy parts of the body. Interestingly, high atomic number (high-Z) metal nanocrystals as X-ray sensitizers can reduce the radiation dose effectively due to their high X-ray absorption, which has attracted increased attention in recent years. High-Z metal nanocrystals produce Auger and photoelectrons electrons under X-ray irradiation, which could generate large amounts of reactive oxygen species, and induce cellular damages. The sensitization effect of high-Z metal nanocrystals is closely related with their composition, morphologies, and size, which would strongly impact their performances in the application of cancer imaging and therapy. In this review, we summarize diverse types of X-ray sensitizers such as bismuth, hafnium, gold, and gadolinium for cancer RT and imaging applications. In addition, current challenges and the outlook of RT based on high-Z metal nanocrystals are also discussed.

Multimodal imaging in the second near-infrared window (NIR-II) guided cancer therapy is a highly precise and efficient cancer theranostic strategy. However, it is still a challenge to develop activated NIR-II optical imaging and therapy agents. In this study, we develop a pH-responsive hybrid plasmonic-fluorescent vesicle by self-assembly of amphiphilic plasmonic nanogapped gold nanorod (AuNNR) and fluorescent down-conversion nanoparticles (DCNP) (AuNNR-DCNP Ve), showing remarkable and activated NIR-II fluorescence (FL)/NIR-II photoacoustic (PA) imaging performances. The hybrid vesicle also exhibited superior loading capacity of doxorubicin as a superior drug carrier and efficient radiosensitizer for X-ray-induced radiotherapy. Interestingly, the accumulated hybrid AuNNR-DCNP Ve in the tumor resulted in a recovery of NIR-II FL imaging signal and a variation in NIR-II PA imaging signal. Dual activated NIR-II PA and FL imaging of the hybrid vesicle could trace drug release and precisely guided cancer radiotherapy to ultimately reduce the side effects to healthy tissue.