Recently, Mn(II)-containing nanoparticles have been explored widely as an attractive alternative to Gd(III)-based T -weighted magnetic resonance imaging (MRI) contrast agents (CAs) for cancer diagnosis. However, as far as it is known, no Mn-based MRI CAs have been reported to sensitively respond to a very weakly acidic environment (pH 6.5-7.0, i.e., the pH range in a tumor microenvironment) with satisfactory imaging performance. Here, recently devised pH-ultrasensitive Mn-based layered double hydroxide (Mn-LDH) nanoparticles with superb longitudinal relaxivity (9.48 mm s at pH 5.0 and 6.82 mm s at pH 7.0 vs 1.16 mm s at pH 7.4) are reported, which may result from the unique microstructure of Mn ions in Mn-LDH, as demonstrated by extended X-ray absorption fine structure. Further in vivo imaging reveals that Mn-LDH nanoparticles show clear MR imaging for tumor tissues in mice for 2 d post intravenous injection. Thus, this novel Mn-doped LDH nanomaterial, together with already demonstrated capacity for drug and gene delivery, is a very potential theranostic agent for cancer diagnosis and treatment.

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A visible-light responsive photocatalyst was fabricated by anchoring NiTi-layered double hydroxide (NiTi-LDH) nanosheets to the surface of reduced graphene oxide sheets (RGO) via an in situ growth method; the resulting NiTi-LDH/RGO composite displays excellent photocatalytic activity toward water splitting into oxygen with a rate of 1.968 mmol g(-1) h(-1) and a quantum efficiency as high as 61.2% at 500 nm, which is among the most effective visible-light photocatalysts. XRD patterns and SEM images indicate that the NiTi-LDH nanosheets (diameter: 100-200 nm) are highly dispersed on the surface of RGO. UV-vis absorption spectroscopy exhibits that the introduction of RGO enhances the visible-light absorption range of photocatalysts, which is further verified by the largely decreased band gap (∼1.78 eV) studied by cyclic voltammetry measurements. Moreover, photoluminescence (PL) measurements indicate a more efficient separation of electron-hole pairs; electron spin resonance (ESR) and Raman scattering spectroscopy confirm the electrons transfer from NiTi-LDH nanosheets to RGO, accounting for the largely enhanced carrier mobility and the resulting photocatalytic activity in comparison with pristine NiTi-LDH material. Therefore, this work demonstrates a facile approach for the fabrication of visible-light responsive NiTi-LDH/RGO composite photocatalysts, which can be used as a promising candidate in solar energy conversion and environmental science.

Visibly clear: A family of visible‐light‐responsive MCr–layered double hydroxides (LDHs; M=Cu, Ni, Zn) were synthesized. These show remarkable photocatalytic activity with visible‐light irradiation. Experimental and computational studies revealed that the visible‐light response of MCrNO3–LDHs originates from a d–d transition in the orderly dispersed CrO6 octahedra in the hydrotalcite layer.

Immunogenic cancer cell death (ICD) is drawing worldwide attention as it allows dying cancer cells to regulate the host's anti-tumor immune system and awaken immunosurveillance. Thus, effectively activating therapy-induced ICD is of great clinical significance to raise systemic anti-tumor immunity and eradicate post-treatment/abscopal cancer tissues. Enhanced cytotoxic reactive oxygen species (ROS) generation in cancer therapy has been positively correlated to ICD induction, which inspires design of a therapy-induced ICD amplifier. The nanohybrid amplifier (FeOOH@STA/Cu-LDH) is devised based on Cu-containing layered double hydroxide (Cu-LDH), incorporating ROS inducer (FeOOH nanodots), ROS generation booster (Cu-LDH for photothermal therapy), and heat shock protein inhibitor (STA). Treating 4T1 tumor cells with this amplifier translocates calreticulins (CRT, one of main ICD signals) on the surface of dying cancer cells, which achieves the maximum at fever-type temperature (40-42 °C). To demonstrate immunotherapeutic efficacy of this nanohybrid, 4T1 tumor-bearing mouse model is established with primary and abscopal tumors. Significantly, only one treatment with the ICD amplifier eradicates the primary tumor and inhibits the abscopal tumor growth upon fever-type heating and induces more cytotoxic T lymphocytes in abscopal tumors and spleens after treatment for 1 week. This research thus provides a new insight into nanomaterial-mediated tumor immunotherapy.

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