To integrate real-time monitoring and therapeutic functions into a single nanoagent, we have designed and synthesized a drug-delivery platform based on a polydopamine(PDA)/human serum albumin (HSA)/doxorubicin (DOX) coated bismuth selenide (Bi2Se3) nanoparticle (NP). The resultant product exhibits high stability and biocompatibility both in vitro and in vivo. In addition to the excellent capability for both X-ray computed tomography (CT) and infrared thermal imaging, the NPs possess strong near-infrared (NIR) absorbance, and high capability and stability of photothermal conversion for efficient photothermal therapy (PTT) applications. Furthermore, a bimodal on-demand pH/photothermal-sensitive drug release has been achieved, resulting in a significant chemotherapeutic effect. Most importantly, the tumor-growth inhibition ratio achieved from thermo-chemotherapy of the Bi2Se3@PDA/DOX/HSA NPs was 92.6%, in comparison to the chemotherapy (27.8%) or PTT (73.6%) alone, showing a superior synergistic therapeutic effect. In addition, there is no noticeable toxicity induced by the NPs in vivo. This multifunctional platform is, therefore, promising for effective, safe and precise antitumor treatment and may stimulate interest in further exploration of drug loading on Bi2Se3 and other competent PTT agents combined with in situ imaging for biomedical applications.

Theranostic agents for magnetic resonance imaging (MRI) guided photothermal therapy have attracted intensive interest in cancer diagnosis and treatment. However, the development of biocompatible theranostic agents with high photothermal conversion efficiency and good MRI contrast effect remains a challenge. Herein, PEGylated Mn2+-chelated polydopamine (PMPDA) nanoparticles were successfully developed as novel theranostic agents for simultaneous MRI signal enhancement and photothermal ablation of cancer cells, based on intrinsic manganese-chelating properties and strong near-infrared absorption of polydopamine nanomaterials. The obtained PMPDA nanoparticles showed significant MRI signal enhancement for both in vitro and in vivo imaging. Highly effective photothermal ablation of HeLa cells exposed to PMPDA nanoparticles was then achieved upon laser irradiation for 10 min. Furthermore, the excellent biocompatibility of PMPDA nanoparticles, because of the use of Mn2+ ions as diagnostic agents and biocompatible polydopamine as photothermal agents, was confirmed by a standard MTT assay. Therefore, the developed PMPDA nanoparticles could be used as a promising theranostic agent for MRI-guided photothermal therapy of cancer cells.

Development of stimuli-responsive theranostics is of great importance for precise cancer diagnosis and treatment. Herein, bovine serum albumin (BSA) modified bismuth nanoraspberries (Bi-BSA NRs) are developed as cancer theranostic agents for multimodal imaging and chemo-photothermal combination therapy. The Bi-BSA NRs are synthesized in aqueous phase via a facile reduction method using Bi 2 O 3 nanospheres as the sacrificial template. The morphology, biocompatibility, photothermal effect, drug loading/releasing abilities, chemotherapy effect, synergistic chemo-photothermal therapy efficacy, and multimodal imaging capacities of Bi-BSA NRs have been investigated. The results show that the NRs possess multiple unique features including (i) raspberry-like morphology with high specific surface area (∼52.24 m 2 •g −1 ) and large cavity (total pore volume ∼0.30 cm 3 •g −1 ), promising high drug loading capacity (∼69 wt %); (ii) dual-stimuli responsive drug release, triggered by acidic pH and NIR laser irradiation; (iii) infrared thermal (IRT), photoacoustic (PA) and X-ray computed tomography (CT) trimodality imaging with the CT contrast enhanced efficiency as high as ∼66.7 HU•mL•mg −1 ; (iv) 100% tumor elimination through the combination chemo-photothermal therapy. Our work highlights the great potentials of Bi-BSA NRs as a versatile theranostics for multimodal imaging and combination therapy.

Antibacterial efficiency can be effectively improved by applying targeting antibacterial materials and strategies. Herein, the successful synthesis of uniform pH-responsive Ag nanoparticle clusters (AgNCs) is demonstrated, which can collapse and reassemble into nonuniform Ag NPs upon exposure to the acidic microenvironment of bacterial infections. This pH triggered reassembly contributes greatly to the improved antibacterial activities of AgNCs against both methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The minimum inhibitory concentration and minimum bactericidal concentration against MRSA are as low as 4 and 32 µg mL −1 (which are 8 and 32 µg mL −1 for E. coli), respectively. In vivo skin wound healing experiments confirm AgNCs can serve as an effective wound dressing to accelerate the healing of MRSA infection. The development of responsive AgNCs offers new materials and strategies in targeting antibacterial applications.

Colitis-associated colorectal cancer (CAC), in which chronic inflammation is a well-recognized carcinogen, requires concurrent anti-inflammation and antitumor treatments in the clinic. Herein, we report polyethylene glycol (PEG)-coated (PEGylated) ultrasmall rhodium nanodots (Rh-PEG NDs) can serve as a metallic nanozyme with reactive oxygen and nitrogen species (RONS) scavenging properties as well as photothermal activities for anti-inflammation and antitumor theranostics in colon diseases. Benefiting from multienzyme activities against RONS, Rh-PEG NDs can decrease the levels of pro-inflammatory cytokines (TNF-α, IL-6), resulting in good anti-inflammatory effect on dextran sulfate sodium-induced colitis. By virtue of high photothermal conversion efficiency (48.9%), Rh-PEG NDs demonstrate complete ablation of CT-26 colon tumor without any recurrence. Most importantly, Rh-PEG NDs exhibit good biocompatibility both at the cellular and animal levels. Our findings provide a paradigm to utilize metallic nanozymes for the potential management of colon diseases.