Cation Exchange Protocols to Radiolabel Aqueous Stabilized ZnS, ZnSe, and CuFeS2 Nanocrystals with 64Cu for Dual Radio- and Photo-Thermal Therapy

Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

In recent years, low-dimensional transition metal chalcogenide (TMC) materials have garnered growing research attention due to their superior electronic, optical, and catalytic properties compared to their bulk counterparts. The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications. In this context, the atomic substitution method has emerged as a favorable approach. It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely, crystal structures, and inherent properties of the resulting materials. In this review, we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional, one-dimensional and two-dimensional TMC materials. The effects of substituting elements, substitution ratios, and substitution positions on the structures and morphologies of resulting material are discussed. The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided, emphasizing the role of atomic substitution in achieving these advancements. Finally, challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

Neodymium and manganese ions co-doped whitlockite for temperature monitoring, photothermal therapy, and bone tissue repair in osteosarcoma

Osteosarcoma is one of the most dangerous forms of tumors, leading to death in >90% of patients. The surgical treatment of osteosarcoma results in significant bone defects and risks of tumor recurrence. Using neodymium (Nd) and manganese (Mn) ions co-doped with whitlockite nanoparticle (Nd10%Mn10%WH NPs) and sodium alginate (SA), we designed and synthesized an organic-inorganic composite hydrogel (Nd10%Mn10%WH-SA) that displayed the excellent fluorescence and photothermal properties. Furthermore, the maximum fluorescence emission intensity of Nd10%Mn10%WH-SA at 1062 nm was linear with temperature. The optimal temperature for the treatment of tumors was determined by considering the changes in fluorescence intensity that led to a reduction in tissue damage around the tumors. Nd10%Mn10%WH NPs demonstrated a significant function in promoting human bone marrow mesenchymal stem cells (hBMSCs) proliferation. Furthermore, Nd10%Mn10%WH-SA could almost kill tumors when the photothermal temperature was raised to 50 °C, with a minimal leftover scar after photothermal therapy (PTT). Nd10%Mn10%WH-SA had a better promotion effect on the growth of the new bone. These results suggested that Nd10%Mn10%WH-SA offers a new PTT method for the "integrated treatment and repair" of osteosarcoma.

Remarkable Electrical Conductivity Increase and Pure Metallic Properties from Semiconducting Colloidal Nanocrystals by Cation Exchange for Solution-Processable Optoelectronic Applications

The authors report a strategic approach to achieve metallic properties from semiconducting CuFeS colloidal nanocrystal (NC) solids through cation exchange method. An unprecedentedly high electrical conductivity is realized by the efficient generation of charge carriers onto a semiconducting CuS NC template via minimal Fe exchange. An electrical conductivity exceeding 10 500 S cm^-1 (13 400 S cm^-1 at 2 K) and a sheet resistance of 17 Ω/sq at room temperature, which are among the highest values for solution-processable semiconducting NCs, are achieved successfully from bornite-phase CuFeS NC films possessing 10% Fe atom. The temperature dependence of the corresponding films exhibits pure metallic characteristics. Highly conducting NCs are demonstrated for a thermoelectric layer exhibiting a high power factor over 1.2 mW m^-1 K^-2 at room temperature, electrical wires for switching on light emitting diods (LEDs), and source-drain electrodes for p- and n-type organic field-effect transistors. Ambient stability, eco-friendly composition, and solution-processability further validate their sustainable and practical applicability. The present study provides a simple but very effective method for significantly increasing charge carrier concentrations in semiconducting colloidal NCs to achieve metallic properties, which is applicable to various optoelectronic devices.

Fe3 O4 @Au@Cu2-x S Heterostructures Designed for Tri-Modal Therapy: Photo- Magnetic Hyperthermia and 64 Cu Radio-Insertion

Here, the synthesis and proof of exploitation of three-material inorganic heterostructures made of iron oxide-gold-copper sulfide (Fe₃ O₄ @Au@Cu_2-x S) are reported. Starting with Fe₃ O₄ -Au dumbbell heterostructure as seeds, a third Cu_2-x S domain is selectively grown on the Au domain. The as-synthesized trimers are transferred to water by a two-step ligand exchange procedure exploiting thiol-polyethylene glycol to coordinate Au and Cu_2-x S surfaces and polycatechol-polyethylene glycol to bind the Fe₃ O₄ surface. The saline stable trimers possess multi-functional properties: the Fe₃ O₄ domain, of appropriate size and crystallinity, guarantees optimal heating losses in magnetic hyperthermia (MHT) under magnetic field conditions of clinical use. These trimers have indeed record values of specific adsorption rate among the inorganic-heterostructures so far reported. The presence of Au and Cu_2-x S domains ensures a large adsorption which falls in the first near-infrared (NIR) biological window and is here exploited, under laser excitation at 808 nm, to produce photo-thermal heat alone or in combination with MHT obtained from the Fe₃ O₄ domain. Finally, an intercalation protocol with radioactive ⁶⁴ Cu ions is developed on the Cu_2-x S domain, reaching high radiochemical yield and specific activity making the Fe₃ O₄ @Au@Cu_2-x S trimers suitable as carriers for ⁶⁴ Cu in internal radiotherapy (iRT) and traceable by positron emission tomography (PET).

Phase-Controlled Synthesis and Quasi-Static Dielectric Resonances in Silver Iron Sulfide (AgFeS2 ) Nanocrystals

Ternary metal-chalcogenide semiconductor nanocrystals are an attractive class of materials due to their tunable optoelectronic properties that result from a wide range of compositional flexibility and structural diversity. Here, the phase-controlled synthesis of colloidal silver iron sulfide (AgFeS₂ ) nanocrystals is reported and their resonant light-matter interactions are investigated. The product composition can be shifted selectively from tetragonal to orthorhombic by simply adjusting the coordinating ligand concentration, while keeping the other reaction parameters unchanged. The results show that excess ligands impact precursor reactivity, and consequently the nanocrystal growth rate, thus deterministically dictating the resulting crystal structure. Moreover, it is demonstrated that the strong ultraviolet-visible extinction peak exhibited by AgFeS₂ nanocrystals is a consequence of a quasi-static dielectric resonance (DR), analogous to the optical response observed in CuFeS₂ nanocrystals. Spectroscopic studies and computational calculations confirm that a negative permittivity at ultraviolet/visible frequencies arises due to the electronic structure of these intermediate-band (IB) semiconductor nanocrystals, resulting in a DR consisting of resonant valence-band-to-intermediate-band excitations, as opposed to the well-known localized surface plasmon resonance response typically observed in metallic nanostructures. Overall, these results expand the current library of an underexplored class of IB semiconductors with unique optical properties, and also enrich the understanding of DRs in ternary metal-iron-sulfide nanomaterials.

Synthesis of one-for-all type Cu5FeS4 nanocrystals with improved near infrared photothermal and Fenton effects for simultaneous imaging and therapy of tumor

CuS materials exhibit excellent near infrared (NIR) photoabsorption and photothermal effect, but they are lack of magnetic resonance imaging (MRI) ability. Fe-based nanomaterials possess MRI capacity, but they usually exhibit poor NIR photoabsorption. In order to solve the above problems, we synthesize three kinds of Cu_xFe_yS_z samples, including FeS₂, CuFeS₂ and Cu₅FeS₄ nanomaterials. With the Cu/Fe ratios increase from 0/1.0 to 1.0/1.0 and 5.0/1.0, the localized surface plasmon resonances (LSPRs) characteristic peaks shift to longer wavelength, and the photothermal transduction efficiencies go up from 24.4% to 36.6% and 45.9%. Thus, Cu₅FeS₄ is found to be the most excellent sample. Especially, Cu₅FeS₄ exhibits photothermal-enhanced Fenton effect, which can produce hydroxyl radical (·OH) under a wide pH range (e.g., pH = 5.4-7.4) to realize the chemodynamic effect. In addition, Cu₅FeS₄ can be employed as an efficient MRI contrast agent. When Cu₅FeS₄ dispersion is intravenously injected into the mouse, the tumor can be detected by MRI as well as thermal imaging, and eliminated through photothermal-enhanced chemodynamic effect. Therefore, Cu₅FeS₄ can be used as an efficient "one-for-all" type agent for MRI-guided photothermal-enhanced chemodynamic therapy of tumor.