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In this study, spherical Ag+-poor Ag2S nanoparticles (∼15.8 nm) with uniform distribution (∼2.1 nm) were successfully synthesized using a one-step aqueous phase method. They exhibited good optical absorption properties and pH stability. First-principles calculations show that Ag deficiency leads to the decreased contribution originating from the transition from Ag 4d orbitals to S 3p orbitals and the reduced absorbance at 635 nm. Then, sesame ball-like Zn2Ga2.92Hf0.045Ge0.75O8:Cr0.02–Ag2S (ZGGO:Cr,Hf–Ag2S) composite nanoplatforms with fluorescence-background-free temperature sensing were constructed by electrostatic adsorption of Ag+-poor Ag2S nanoparticles onto the surfaces of near-spherical ZGGO:Cr,Hf nanoparticles. It is found that their photothermal conversion efficiency is about 46% upon 635 nm excitation. In addition, they showed good photothermal stability and biocompatibility and enhanced photothermal conversion ability in response to acidic pH environments. As the tissue thickness reaches 5 mm, the bactericidal rates of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) can reach about 72% and 64%, respectively. Meanwhile, the sesame ball-like ZGGO:Cr,Hf–Ag2S composite nanoplatforms with broad-spectrum bactericidal performance can be used as afterglow ratio nanothermometers to realize real-time temperature monitoring during therapy processes. The temperature sensitivity is found to increase from 0.052 to 0.054 K−1 with increasing temperature from 307 to 320 K. The temperature difference between the noncontact and direct measurements is about 0.78 °C, suggesting that the constructed sesame ball-like composite nanoplatforms can realize noncontact temperature sensing and deep tissue sterilization using a 635 nm laser excitation at the same time. [ABSTRACT FROM AUTHOR]

In this study, Zn2(1−x)Ni2xGa3Ge0.75O8 (x = 0.0002, 0.001, 0.002, 0.010, 0.020, and 0.030) nanoparticles with broadband NIR‐II emissions were synthesized by a hydrothermal synthesis combined with a vacuum annealing. For the Ni2+‐doped ZGGO samples (x = 0–0.03), with increasing concentration, the particle shape gradually becomes spherical and the average particle size decreases from 124.4 to 74.2 nm. Meanwhile, for the ZGGO:Ni2+0.01 nanoparticles, the asymmetrically broad emission peak around 1290 nm, which is the superposition of the two peaks locating at 1280 and 1450 nm, can be observed and the afterglow time exceeds 30 min. Based on the spectral data, luminescence decay curves, first‐principles calculations, and Tanabe–Sugano theory, it is found that Ni2+ ions can occupy not only tetrahedral but also octahedral Zn2+ sites (locating in anti‐site defects pair) in the spinel ZGGO host, and they have the contributions to the 1450 and 1280 nm emission peaks, respectively. Furthermore, the surface‐modified ZGGO:Ni2+ nanoparticles exhibited good stability in the H2O and HSA (5% human serum albumin, pH = 7.4) solutions and the occurred agglomeration sinking in the SLS (simulate lysosomal solution, pH = 4.7) solution. Compared to the narrow‐band NIR‐II emitting persistent luminescence nanoparticles (ZGGO:Cr3+,Er3+ and ZGGO:Cr3+,Nd3+), broadband NIR‐II emitting persistent luminescence nanoparticles (ZGGO:Ni2+ NIR‐II) possess stronger persistent luminescence intensity and can effectively avoid the water absorption of biological tissues. Our results suggest that ZGGO:Ni2+ persistent luminescence nanoparticles have a potential to become optical probes for deep‐tissue autofluorescence‐free bioimaging in the biomedical field. [ABSTRACT FROM AUTHOR]

Poly(sodium 4-styrenesulfonate) (PSS) molecule modified PLNP-Bi2S3 composite nanoplatforms were constructed by using polyvinylpyrrolidone (PVP) modified Bi2S3 nanoparticles (∼4.6 nm) as a photothermal agent and hexadecyl trimethyl ammonium bromide (CTAB) coated Zn2Ga2.98Ge0.75O8:Cr0.023+ (ZGGO:Cr3+@CTAB) persistent luminescence nanoparticles (PLNPs) through electrostatic adsorption. It is found that the above composite nanoplatforms have excellent laser-irradiation thermal stability and good photothermal conversion performance. The measured photothermal conversion efficiency is ∼44%, which is higher than that (∼37%) of the PLNP-GNR (gold nanorod) composite nanoplatforms. Meanwhile, PSS modified PLNP-Bi2S3 composite nanoplatforms exhibited good solution dispersibility in blood and normal tissue environments. While reaching tumor sites, the above composite nanoplatforms can be rapidly accumulated in cancer cells with acidic environments. This pH-responsive acid-induced aggregation can be ascribed to the chemical reaction induced by the protonation of PSS modified PLNP-Bi2S3 composite nanoplatforms with a negatively charged surface in the acidic environments. Our results suggest that PSS modified PLNP-Bi2S3 composite nanoplatforms might be applied to precision diagnosis and therapy of deep-tissue tumors. [ABSTRACT FROM AUTHOR]