ACS Applied Nano Materials最新文献

{"title":"Two Methods for the Experimental Determination of the Relaxation Time and SPA of Magnetic Nanoparticles under RF Fields: Implications for Nanowarming and Hyperthermia","authors":"Ignacio J. Bruvera,&nbsp;, ,&nbsp;Giuliano Andrés Basso,&nbsp;, ,&nbsp;Josefina Medina,&nbsp;, ,&nbsp;Daniel Actis,&nbsp;, ,&nbsp;Gustavo Pasquevich,&nbsp;, and ,&nbsp;Pedro Mendoza Zélis*,&nbsp;","doi":"10.1021/acsanm.5c02740","DOIUrl":"https://doi.org/10.1021/acsanm.5c02740","url":null,"abstract":"<p >In applications such as hyperthermia and nanowarming, power dissipation arises when the time-dependent magnetization <i>M</i>(<i>t</i>) of an out-of-equilibrium system of nanoparticles lags behind the applied magnetic field <i>H</i>(<i>t</i>). The key parameter governing this process is the relaxation time τ, which induces a phase shift ϕ_<i>n</i> between <i>H</i>(<i>t</i>) and each <i>n-</i>th harmonic component of <i>M</i>(<i>t</i>). In this work, we present two methods to obtain the effective value of τ from radiofrequency field (RF) magnetization measurements. One method derives the result directly from ϕ_<i>n</i>, while the other fits the <i>M</i>(<i>H</i>) cycle using a time-delayed superparamagnetic response. We compare these methods applied to the variation of τ for magnetic nanoparticles under an RF field in two experiments: the solid-to-liquid transition of an aqueous suspension of particles and the effect of increasing concentration of the suspension.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 42","pages":"20188–20195"},"PeriodicalIF":5.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145339567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MOF-Derived Nanoporous Co3O4 Dodecahedrons for Tunable High-Order Harmonic Soliton Pulsed Fiber Laser","authors":"Baoyuan Liu*,&nbsp;, ,&nbsp;Fang Peng,&nbsp;, ,&nbsp;Yujiao Chen,&nbsp;, ,&nbsp;Wei Wang,&nbsp;, ,&nbsp;Zhiwen Pan,&nbsp;, ,&nbsp;Rui Zhang,&nbsp;, and ,&nbsp;Xiaohui Li*,&nbsp;","doi":"10.1021/acsanm.5c02798","DOIUrl":"https://doi.org/10.1021/acsanm.5c02798","url":null,"abstract":"<p >Metal–organic frameworks (MOFs) are a class of highly porous crystalline materials composed of metal centers and organic ligands, offering remarkable versatility in catalysis and optoelectronic applications due to their unique structural properties and exceptionally high specific surface areas. A nanostructured Co₃O₄-based dodecahedral cone-saturated absorber demonstrates significant nonlinearity at a wavelength of 1550 nm, achieving a modulation depth of 13.1% and a saturation intensity of 10.6 MW/cm². At 1564.6 nm, this material generates soliton pulses with a pulse width of 1.08 ps and a modulation interval of 4 ps. By optimizing the resonator structure, tunable high-harmonic soliton pulses ranging from 4.5 to 333 MHz are realized. The enhanced nanostructured properties of this MOF material play a pivotal role in significantly boosting the performance of fiber lasers, offering enhanced flexibility and adaptability for optical signal transmission. This breakthrough also opens avenues for the development of advanced optoelectronic devices, including ultracompact optical switches, optical memory, and quantum communication technologies, marking a significant step toward the next generation of nanoenabled optoelectronic applications.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 42","pages":"20196–20204"},"PeriodicalIF":5.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145339577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of Antimicrobial Nanocomplexes Using Argon Plasma Chemistry","authors":"Kyle Richards,&nbsp;, ,&nbsp;Jonathan Nunez,&nbsp;, ,&nbsp;Janeen Darwish,&nbsp;, ,&nbsp;Daniel Centeno,&nbsp;, ,&nbsp;Tsengming Chou,&nbsp;, ,&nbsp;Camila Mafla,&nbsp;, ,&nbsp;Thomas Cattabiani,&nbsp;, ,&nbsp;Ashwin Ambi,&nbsp;, and ,&nbsp;Christian Traba*,&nbsp;","doi":"10.1021/acsanm.5c03318","DOIUrl":"https://doi.org/10.1021/acsanm.5c03318","url":null,"abstract":"<p >Plasma chemistry was employed as first the oxidizing and then the reducing agent in separate steps of a surface modification approach. More specifically, argon plasma chemistry coupled with the “grafting-from” approach was used to engineer an innovative and antibiotic-free nanocomplex. Through covalent binding of monomeric acrylic acid to a substrate in a “bottom-up” approach, a negatively charged nanocoating forms upon exposure to solutions of 2 mM silver nitrate. Through electrostatic interactions, the polymer brushes of the nanocoating can specifically bind to Ag⁺, which creates a platform for the <i>in situ</i> reduction of Ag⁺ to Ag⁰ using only argon plasma technology. By controlling grafting-, reduction-, and metal-binding conditions, we can generate antibiotic-free anti-infection nanocomplexes with controllable grafting density, polymer brush length, and silver nanoparticle (AgNP) concentration and size. We have used this technology to engineer nanocomplexes with polymer brush densities of 70 μg/cm² and dry brush polymer lengths of 144 nm. Under appropriate experimental conditions, AgNPs with typical sizes of 50–100 nm are synthesized and bound to polymer brushes in the nanocoating. Using these immobilization platforms, very low amounts of AgNPs (2.46 μg/cm²) can be bound to the nanocoating. The resulting nanocomplexes were found to be extremely effective at eradicating <i>S. epidermidis</i>, <i>E. coli</i>, and <i>S. aureus</i> biofilms <i>in vitro</i>. The anti-infection nanocomplexes combat infections by directly dealing with attached bacteria to eradicate biofilm-associated infections. Results indicate that these biocompatible nanocoatings kill bacteria by interacting with the cell membranes of bacteria to cause cell death through lysis. These stable, biocompatible nanocoatings present a promising antibiotic-free strategy for preventing device-associated infections.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 42","pages":"20277–20285"},"PeriodicalIF":5.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145339613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spinel ZnCo2O4 Nanosheets Supported on Ni Foam as Electrocatalysts for the Oxygen Evolution Reaction","authors":"Jianjun Shi,&nbsp;, ,&nbsp;Di Yu,&nbsp;, ,&nbsp;Xuehua Yu,&nbsp;, ,&nbsp;Bauyrzhan Sarsenbekuly,&nbsp;, ,&nbsp;Zhen Zhao*,&nbsp;, ,&nbsp;Wanli Kang*,&nbsp;, and ,&nbsp;Saule B. Aidarova*,&nbsp;","doi":"10.1021/acsanm.5c03884","DOIUrl":"https://doi.org/10.1021/acsanm.5c03884","url":null,"abstract":"<p >Oxygen evolution reaction (OER) involves the multistep atomic coupling electron transfer process, which serves as the rate-limiting step in electrocatalytic water splitting. Hence, the design of OER catalysts with high performance and stability represents a critical factor in promoting the oxygen evolution reaction. In this study, ZC/NF-m<i>_n</i> catalysts were fabricated by the hydrothermal method, achieving the in situ growth of spinel active phase (ZnCo₂O₄) on the three-dimensional porous skeleton of nickel foam. Among these catalysts, the ZC/NF-m₂ catalyst requires an overpotential of only 222 mV at a current density of 10 mA·cm^–2 in neutral medium. Multiple characterization results demonstrate that the OER performance of the ZC/NF-m₂ catalyst with ZnCo₂O₄ phase is superior to that of the single metal oxides (Co₃O₄ and ZnO) owing to the synergistic effects of the multicomponent system. More importantly, an appropriate growth amount of the spinel active phase not only optimizes the morphology properties but also provides abundant oxygen vacancies and Co²⁺–O_v structures on the catalyst surface, which are crucial for the adsorption of molecular oxygen and electron transfer during the oxygen evolution process. The ZC/NF-m₂ catalyst with excellent stability and efficient electrocatalytic performance presents a design strategy for developing non-precious-metal materials for oxygen evolution reaction.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"20077–20087"},"PeriodicalIF":5.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LaS/CoS2 Heterojunction Nanorods for Enhanced Bifunctional Oxygen Catalysis in Zinc–Air Batteries","authors":"Chenyao Chen,&nbsp;, ,&nbsp;Yuchan Liu,&nbsp;, ,&nbsp;Wenjing Gao,&nbsp;, ,&nbsp;Huihuan Ouyang,&nbsp;, ,&nbsp;Rongkai Ye*,&nbsp;, and ,&nbsp;Jianqiang Hu*,&nbsp;","doi":"10.1021/acsanm.5c03702","DOIUrl":"https://doi.org/10.1021/acsanm.5c03702","url":null,"abstract":"<p >Conventional rechargeable zinc–air batteries (RZABs) are largely hindered by the sluggish reaction kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode. Therefore, the rational design of highly active bifunctional electrocatalysts is crucial for advancing performance of the energy storage system. In this study, we synthesized uniform porous LaS/CoS₂ heterojunction nanorods, in which LaS was introduced into transition metal sulfide to construct abundant sulfur vacancies and well-defined heterointerfaces. This not only effectively regulated the electronic structure of the LaS/CoS₂ heterojunctions but also significantly enhanced their bifunctional catalytic activity, which possessed an ORR/OER voltage gap of as low as 0.72 V. The RZAB assembled with LaS/CoS₂ as an air cathode had a high peak power density of ca. 190 mW cm^–2, stable open-circuit voltage of ca. 1.54 V, and remarkable specific capacity of ca. 801.7 mAh g_Zn^–1. The RZAB device maintained stable charge–discharge cycling over 480 h with negligible performance degradation, surpassing the performance of conventional Pt/C and RuO₂-based counterparts across multiple evaluation metrics. This work elucidated the synergistic effect between sulfur vacancies and heterojunction interfaces and mechanistic insight into their role in promoting electrocatalytic activity. These findings provide a promising strategy for the design of efficient and durable bifunctional catalysts for next-generation metal–air batteries.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"19996–20005"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LED-Activated NIR-II Gold Nanorods for Photothermal Therapy of 3D Melanoma Spheroids","authors":"Alexandru Holca,&nbsp;, ,&nbsp;Raluca Borlan,&nbsp;, ,&nbsp;Andreea Campu,&nbsp;, ,&nbsp;Stefan Dragan,&nbsp;, ,&nbsp;Mara Muntean,&nbsp;, ,&nbsp;Ana-Maria Craciun,&nbsp;, ,&nbsp;Alina Sesarman,&nbsp;, ,&nbsp;Manuela Banciu,&nbsp;, ,&nbsp;Simion Astilean,&nbsp;, ,&nbsp;Marc Lamy de la Chapelle*,&nbsp;, and ,&nbsp;Monica Focsan*,&nbsp;","doi":"10.1021/acsanm.5c03202","DOIUrl":"https://doi.org/10.1021/acsanm.5c03202","url":null,"abstract":"<p >Thermoplasmonics, an emerging field focused on heat generation via localized surface plasmon resonance (LSPR) in metallic nanostructures, presents significant potential for light-to-heat conversion in biomedical contexts. In this study, we report a distinct class of gold nanorods (GNRs) with longitudinal LSPRs spanning from 985 to 1282 nm, precisely tuned within the second near-infrared (NIR-II) biological window, as excellent photothermal candidates. To evaluate their intrinsic performance, colloidal suspensions of these GNRs were irradiated with low-power, low-cost LED sources emitting across a wide spectral range (505–1100 nm), both in and out of resonance with their plasmonic bands. Real-time thermal imaging was used to monitor heating and cooling dynamics, and photothermal conversion efficiency (η) was analytically determined, reaching values as high as 72%. Transmission electron microscopy (TEM) and UV–vis-NIR spectroscopy confirmed the high morphological uniformity and optical tunability of the nanorods, while finite-difference time-domain (FDTD) simulations provided further evidence for their absorption-driven behavior. Furthermore, in vitro experiments on B16.F10 melanoma cells, grown as monolayers (2D culture) or as spheroids (3D culture), demonstrated a dose-dependent toxicity of GNR 1060 over a wide range of studied concentrations. However, PEGylation of the GNR 1060 improved biocompatibility toward the B16.F10 melanoma cells in both monolayers and spheroids. When irradiated with an 1100  nm LED, both free and PEGylated GNR 1060 showed a promising photothermal effect, reducing the viability of melanoma spheroids by up to 40%. The photothermal effect of irradiated GNR 1060 in spheroids was also confirmed by 3D rescan confocal fluorescence imaging, which revealed cytotoxicity consistent with viability assay results. These findings demonstrate the robust thermoplasmonic capabilities of NIR-II GNRs and their potential as efficient, LED-activated nanoheaters for noninvasive cancer therapy.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"19796–19809"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Manganese-Doped Zeolite Imidazolium-Based Nanoplatform for MRI-Guided Sonodynamic and Chemodynamic Cancer Therapy","authors":"Qi Xu*,&nbsp;, ,&nbsp;Qiqi Qi,&nbsp;, ,&nbsp;Zhimin Mo,&nbsp;, ,&nbsp;Han Hu,&nbsp;, ,&nbsp;Yanru Shao,&nbsp;, ,&nbsp;Qianyuan He*,&nbsp;, and ,&nbsp;Zushun Xu*,&nbsp;","doi":"10.1021/acsanm.5c03736","DOIUrl":"https://doi.org/10.1021/acsanm.5c03736","url":null,"abstract":"<p >Multimodal sonodynamic therapy (SDT) is one of the main approaches for future tumor therapy; however, the application of SDT is still hindered by hypoxia and glutathione (GSH) overexpression in the tumor microenvironment (TME). Based on this, we designed manganese-doped zeolitic imidazolate framework-67 (ZIF-67) nanocrystals and encapsulated them with cell membranes to obtain Mn-ZIF-67@CMs (MF@CMs). The ZIF-67 nanocrystals have natural M-N active sites and show potential for application in SDT. Since the TME contains a large amount of H₂O₂, which reacts with Mn²⁺ to release O₂. Meanwhile, Co³⁺ and Mn³⁺ can consume GSH in the TME, which in turn boosts the effectiveness of SDT. Additionally, the reaction that produces Co²⁺ and Mn²⁺ exhibits a Fenton-like mechanism, which further contributes to the therapeutic effects of chemodynamic therapy (CDT). Furthermore, due to the magnetic resonance imaging (MRI) T1 imaging properties of Mn²⁺, these nanoparticles (MF@CMs) also hold potential for integrated diagnosis and treatment. The MF@CMs designed in this study have good biocompatibility, oxygen-producing capacity, and GSH-consuming capacity, indicating the potential for clinical application.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"20029–20041"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic Strain and Electronic Effects in AuCu@CuFePd Core–Shell Nanocatalysts for Acidic Oxygen Reduction Electrocatalysis","authors":"Mengyuan Ma,&nbsp;, ,&nbsp;Zhong Zheng,&nbsp;, ,&nbsp;Hui Liu,&nbsp;, ,&nbsp;Shaonan Tian*,&nbsp;, ,&nbsp;Dong Chen*,&nbsp;, and ,&nbsp;Jun Yang*,&nbsp;","doi":"10.1021/acsanm.5c03515","DOIUrl":"https://doi.org/10.1021/acsanm.5c03515","url":null,"abstract":"<p >Rational design of electrocatalysts that synergize lattice strain and electronic effect is pivotal for enhancing the oxygen reduction reaction (ORR) in acidic media. We, herein, report a core–shell AuCu@CuFePd nanocatalyst synthesized via sequential coreduction and galvanic replacement, where the AuCu alloy core induces interfacial compressive strain on the CuFePd shell, and synergistic interactions between Pd and incorporated transition metals (Cu/Fe) downshift the Pd d-band center, optimizing adsorption energies of oxygen intermediates. The catalyst exhibits a high half-wave potential of 0.85 V vs RHE, a specific activity of 1.33 mA cm^–2, and a mass activity of 1.46 A mg^–1, outperforming commercial Pd/C and most reported Pd-based catalysts in acidic media. This study demonstrates a generalizable strategy for engineering multimetallic nanostructures, offering both high-performance ORR catalysis in acidic environments and a blueprint for synergistic strain–electronic optimization in noble-metal electrocatalysts.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"19919–19928"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoparticles of LaCoO3 Doped with Ce, Sr, Ca, Ba on A-Site as Catalysts for the Alkaline Oxygen Evolution Reaction","authors":"Xiaoying Hou,&nbsp;, ,&nbsp;Junqi Li*,&nbsp;, ,&nbsp;Cang Shi,&nbsp;, ,&nbsp;Zili Zheng,&nbsp;, ,&nbsp;Kun Jiang,&nbsp;, ,&nbsp;Xuying Lei,&nbsp;, and ,&nbsp;Junda Yang,&nbsp;","doi":"10.1021/acsanm.5c03365","DOIUrl":"https://doi.org/10.1021/acsanm.5c03365","url":null,"abstract":"<p >Cobalt-based perovskite oxide catalysts are considered to be a promising catalyst for oxygen evolution reaction (OER) due to their structural tunability and low cost. However, the high free energy of adsorption of reactive intermediates and low conductivity limit further improvement of their OER performance. Here, we show that LaCoO₃ nanoparticles doped with different A-site elements (Ce, Sr, Ca, Ba) all have significantly enhanced catalytic activity. In particular, in 1 M KOH, the 0.1Ce–LaCoO₃ catalyst exhibited superior OER activity to the other catalysts. At a current density of 10 mA cm^–2, the overpotential of the material is as low as 343 mV with a good stability. The comprehensive experimental results show that the introduction of A-site elements into LaCoO₃ can change the geometrical configuration of the CoO₆ octahedron and modulate the electronic states around Co, which, in turn, affects the adsorption of the reaction intermediates on the catalyst surface during the OER process and accelerates the OER reaction process. In this article, we provide a promising strategy for the design and preparation of efficient and low-cost catalysts for the oxygen precipitation reaction by systematically investigating the effects of different A-site element substitutions on the performance of LaCoO₃ OER.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"19901–19909"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Colloidal Synthesis of Ag2MnSnS4 Quantum Dots for Bioimaging Applications","authors":"Chang Jiang,&nbsp;, ,&nbsp;Kazutaka Akiyoshi,&nbsp;, ,&nbsp;Tatsuya Kameyama,&nbsp;, ,&nbsp;Jun Kumagai,&nbsp;, ,&nbsp;Takahisa Yamamoto,&nbsp;, ,&nbsp;Masahiro Yamamoto,&nbsp;, ,&nbsp;Shota Yamada,&nbsp;, ,&nbsp;Naoki Banno,&nbsp;, ,&nbsp;Yutaro Saito,&nbsp;, ,&nbsp;Akira Sumiyoshi,&nbsp;, ,&nbsp;Hiroaki Wake,&nbsp;, ,&nbsp;Hiroshi Yukawa*,&nbsp;, ,&nbsp;Yoshinobu Baba,&nbsp;, and ,&nbsp;Tsukasa Torimoto*,&nbsp;","doi":"10.1021/acsanm.5c03620","DOIUrl":"https://doi.org/10.1021/acsanm.5c03620","url":null,"abstract":"<p >Ag₂MnSnS₄ (AMTS), a member of the multinary I₂–II–IV–VI₄ compound family, exhibits a high absorption coefficient and intrinsic magnetic properties. While bulk AMTS crystals were synthesized via high-temperature solid-state methods, reports of AMTS quantum dots (QDs) remained scarce. Here, we report the first colloidal synthesis of AMTS QDs by optimizing reaction temperature and precursor composition. AMTS QDs obtained at 250 °C were spherical or polygonal with an average size of 5.4 nm or less. Decreasing the Ag fraction in precursors produced Ag-deficient, Mn-rich QDs, exhibiting high tolerance to nonstoichiometry. Their absorption spectra were blue-shifted, and the energy gap increased from 1.95 to 2.36 eV with a decrease in the Ag⁺/metal cation ratio in the precursors from 0.50 to 0.05. Although no photoluminescence (PL) was observed at room temperature, a broad PL peak appeared at 77 K around 740–760 nm. ZnS coating on AMTS QDs enhanced the PL, giving a broad emission at 690 nm. The magnetic properties originated from unpaired 3<i>d</i> electrons of Mn²⁺. For bioimaging applications, ZnS-coated AMTS (AMTS@ZnS) QDs were further modified with 3-mercaptopropionic acid, enabling stable dispersion in water without compromising the optical and magnetic properties. The hydrophilic AMTS@ZnS QDs exhibited high longitudinal relaxivity (<i>r</i>₁), 19 mmol (Mn²⁺)⁻¹ dm³ s^–1, surpassing commercial Mn-based complexes (<i>r</i>₁ &lt; 10 mmol^–1 dm³ s^–1). Although the <i>T</i>₁-weighted MRI intensity was similar at a fixed Mn²⁺ concentration, the QDs prepared with Ag/metal = 0.17 showed 1.7-fold higher relaxivity per QD than those with 0.44. <i>In vivo</i> MRI confirmed a clear signal enhancement at injection sites. The QDs internalized by cells were detectable by MRI in living animals. Given their negligible cytotoxicity compared to Cd-based QDs, AMTS QDs represent a promising next-generation MRI contrast agent, with additional potential for dual-mode bioimaging upon further PL optimization.</p>","PeriodicalId":6,"journal":{"name":"ACS Applied Nano Materials","volume":"8 41","pages":"19952–19967"},"PeriodicalIF":5.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}