ACS Nanoscience Au最新文献

Metalorganic chemical vapor deposition (MOCVD) has become a pivotal technique for developing wafer-scale transition metal dichalcogenide (TMD) 2D materials. This study investigates the impact of MOCVD growth conditions on achieving uniform and selective polymorph phase control of MoTe₂ over large wafers. We demonstrated the controlled and uniform growth of few-layer MoTe₂ in pure 2H, 1T', and mixed phases at various temperatures on up to 4 in. C-plane sapphire wafers with hexagonal boron nitride templates. At 600 °C, high-quality 2H-MoTe₂ was obtained within a narrow temperature window, verified with absorption and TEM analysis. In addition, we observed strong exciton-phonon coupling effects in multiwavelength Raman spectroscopy when the excitation wavelength was in resonance with the C-exciton. Our findings indicate that temperature-induced Te vacancies play a crucial role in determining the MoTe₂ phase. This study highlights the importance of precise control over the MOCVD growth temperature to engineer the MoTe₂ phase of interest for device applications.

Metalorganic chemical vapor deposition (MOCVD) has become a pivotal technique for developing wafer-scale transition metal dichalcogenide (TMD) 2D materials. This study investigates the impact of MOCVD growth conditions on achieving uniform and selective polymorph phase control of MoTe₂ over large wafers. We demonstrated the controlled and uniform growth of few-layer MoTe₂ in pure 2H, 1T′, and mixed phases at various temperatures on up to 4 in. C-plane sapphire wafers with hexagonal boron nitride templates. At 600 °C, high-quality 2H-MoTe₂ was obtained within a narrow temperature window, verified with absorption and TEM analysis. In addition, we observed strong exciton–phonon coupling effects in multiwavelength Raman spectroscopy when the excitation wavelength was in resonance with the C-exciton. Our findings indicate that temperature-induced Te vacancies play a crucial role in determining the MoTe₂ phase. This study highlights the importance of precise control over the MOCVD growth temperature to engineer the MoTe₂ phase of interest for device applications.

Heavy water (D₂O) has found extensive application as a moderator in nuclear reactors. Additionally, it serves as a substitute for regular water (H₂O) in biological or spectroscopic experiments, providing a deuterium source and addressing challenges related to solvent opacity or contrast. This is particularly relevant in experiments involving neutron scattering, infrared absorption, or nuclear magnetic resonance. However, replacing H₂O with D₂O is not always a straightforward or harmless substitution and can instead have unintended chemical consequences. In this study, we highlight the significant impact of solvent deuteration on two common gold nanoparticle syntheses─borohydride reduction and ascorbic acid reduction─by comparing reactions in D₂O and H₂O and mixtures thereof. The resulting colloids exhibit differences in size and spectral characteristics, and their effectiveness as nanocatalysts in the widely used 4-nitrophenol reduction benchmark reaction is adversely affected by the presence of D₂O during both particle synthesis and as the catalytic medium. Ultimately, these results underscore a critical awareness often overlooked by scientists and engineers: despite its widespread and sometimes indispensable use in analytical spectroscopy, cellular imaging, biophysics, and organic chemistry, D₂O cannot truly replace H₂O without significantly altering the chemical environment of a reaction.

Heavy water (D₂O) has found extensive application as a moderator in nuclear reactors. Additionally, it serves as a substitute for regular water (H₂O) in biological or spectroscopic experiments, providing a deuterium source and addressing challenges related to solvent opacity or contrast. This is particularly relevant in experiments involving neutron scattering, infrared absorption, or nuclear magnetic resonance. However, replacing H₂O with D₂O is not always a straightforward or harmless substitution and can instead have unintended chemical consequences. In this study, we highlight the significant impact of solvent deuteration on two common gold nanoparticle syntheses-borohydride reduction and ascorbic acid reduction-by comparing reactions in D₂O and H₂O and mixtures thereof. The resulting colloids exhibit differences in size and spectral characteristics, and their effectiveness as nanocatalysts in the widely used 4-nitrophenol reduction benchmark reaction is adversely affected by the presence of D₂O during both particle synthesis and as the catalytic medium. Ultimately, these results underscore a critical awareness often overlooked by scientists and engineers: despite its widespread and sometimes indispensable use in analytical spectroscopy, cellular imaging, biophysics, and organic chemistry, D₂O cannot truly replace H₂O without significantly altering the chemical environment of a reaction.

Betamethasone dipropionate (BD) is a potent anti-inflammatory drug for atopic dermatitis (AD); however, it leads to serious adverse effects during prolonged use. We aimed to improve the biochemical properties and lower the risk of toxicity by preparing nanoemulsions containing Boesenbergia rotunda rhizome hexane extract (Hex) and essential oils (EO). Physicochemical characterization and 3-month long-term stability testing were conducted. Gas chromatography-mass spectrometry analysis was used to compare the volatile composition after nanoemulsion formulation. Further, various assays related to AD management, including antioxidant potentials, anti-inflammatory activities through inhibition of 5-lipoxygenase and cyclooxygenase-2, and nitric oxide release suppression in lipopolysaccharides-induced RAW 264.7 macrophages, were investigated. In addition, antibacterial activity against Staphylococcus aureus and cytotoxicity to RAW 264.7 macrophages and HaCaT human keratinocyte cells were also evaluated. Monodispersed nanoemulsions (<20 nm) were successfully generated by an ultrasound-assisted method. BD was successfully encapsulated into B. rotunda-based nanoemulsions with more than 95% encapsulation efficiency (EE). The major phytochemicals present in EO and Hex remained after nanoemulsion formulation. The nanoemulsions were compatible with skin pH (5.2-5.8) and exhibited stability with respect to particle size, polydispersity index, transmittance, pH, and EE when stored for 3 months at -20 °C. The BD nanoemulsions loaded with B. rotunda exhibited antioxidant activities and significantly increased the 5-lipoxygenase inhibitory activity. Furthermore, the suppression of nitric oxide release was remarkably enhanced, whereas lower cytotoxicity was observed. The BD nanoemulsions improved the level of involucrin and filaggrin in HaCaT cells, implying their valuable property for skin barrier repair. The formulation of BD into nanoemulsions also enhanced S. aureus inhibition. Either B. rotunda nanoemulsions loaded with or without BD show promise for the topical treatment and prevention of AD.

Betamethasone dipropionate (BD) is a potent anti-inflammatory drug for atopic dermatitis (AD); however, it leads to serious adverse effects during prolonged use. We aimed to improve the biochemical properties and lower the risk of toxicity by preparing nanoemulsions containing Boesenbergia rotunda rhizome hexane extract (Hex) and essential oils (EO). Physicochemical characterization and 3-month long-term stability testing were conducted. Gas chromatography–mass spectrometry analysis was used to compare the volatile composition after nanoemulsion formulation. Further, various assays related to AD management, including antioxidant potentials, anti-inflammatory activities through inhibition of 5-lipoxygenase and cyclooxygenase-2, and nitric oxide release suppression in lipopolysaccharides-induced RAW 264.7 macrophages, were investigated. In addition, antibacterial activity against Staphylococcus aureus and cytotoxicity to RAW 264.7 macrophages and HaCaT human keratinocyte cells were also evaluated. Monodispersed nanoemulsions (<20 nm) were successfully generated by an ultrasound-assisted method. BD was successfully encapsulated into B. rotunda-based nanoemulsions with more than 95% encapsulation efficiency (EE). The major phytochemicals present in EO and Hex remained after nanoemulsion formulation. The nanoemulsions were compatible with skin pH (5.2–5.8) and exhibited stability with respect to particle size, polydispersity index, transmittance, pH, and EE when stored for 3 months at −20 °C. The BD nanoemulsions loaded with B. rotunda exhibited antioxidant activities and significantly increased the 5-lipoxygenase inhibitory activity. Furthermore, the suppression of nitric oxide release was remarkably enhanced, whereas lower cytotoxicity was observed. The BD nanoemulsions improved the level of involucrin and filaggrin in HaCaT cells, implying their valuable property for skin barrier repair. The formulation of BD into nanoemulsions also enhanced S. aureus inhibition. Either B. rotunda nanoemulsions loaded with or without BD show promise for the topical treatment and prevention of AD.

RNA-based agents (siRNA, miRNA, and mRNA) can selectively manipulate gene expression/proteins and are set to revolutionize a variety of disease treatments. Nanoparticle (NP) platforms have been developed to deliver functional mRNA or siRNA inside cells to overcome their inherent limitations. Recent studies have focused on siRNA to knock down proteins causing drug resistance or mRNA technology to introduce tumor suppressors. However, cancer needs multitargeted approaches to selectively manipulate multiple gene expressions/proteins. In this proof-of-concept study, we developed NPs containing Luc-mRNA and siRNA-GFP as model agents ((M+S)-NPs) and showed that NPs can simultaneously deliver functional mRNA and siRNA and impact the expression of two genes/proteins in vitro. Additionally, after in vivo administration, (M+S)-NPs successfully knocked down GFP while introducing luciferase into a TNBC mouse model, indicating that our NPs have the potential to develop RNA-based anticancer therapeutics. These studies pave the way to develop RNA-based, multitargeted approaches for complex diseases like cancer.

RNA-based agents (siRNA, miRNA, and mRNA) can selectively manipulate gene expression/proteins and are set to revolutionize a variety of disease treatments. Nanoparticle (NP) platforms have been developed to deliver functional mRNA or siRNA inside cells to overcome their inherent limitations. Recent studies have focused on siRNA to knock down proteins causing drug resistance or mRNA technology to introduce tumor suppressors. However, cancer needs multitargeted approaches to selectively manipulate multiple gene expressions/proteins. In this proof-of-concept study, we developed NPs containing Luc-mRNA and siRNA-GFP as model agents ((M+S)-NPs) and showed that NPs can simultaneously deliver functional mRNA and siRNA and impact the expression of two genes/proteins in vitro. Additionally, after in vivo administration, (M+S)-NPs successfully knocked down GFP while introducing luciferase into a TNBC mouse model, indicating that our NPs have the potential to develop RNA-based anticancer therapeutics. These studies pave the way to develop RNA-based, multitargeted approaches for complex diseases like cancer.

Cation exchange (CE) has emerged as a premier postsynthetic method to carefully tune the chemical composition and properties of nanocrystals with excellent morphology retention. However, reaction conditions are typically dictated by the ubiquitous ligands bound to their surface, limiting their solubility and influencing the thermodynamics/kinetics of the reaction. To bypass these challenges, we report on CE reactions with Cu⁺, Ag⁺, Cu²⁺, Cd²⁺, Zn²⁺, and Mn²⁺ utilizing ligand-free CdS and Cu _x Se _y thin films as host templates. The exchange reactions could be performed sequentially or simultaneously (i.e., two guest cations) to access compositionally diverse products. The incorporation of cations on the host films was confirmed using SEM-EDS, XPS, and ICP-MS analyses, as well as tracking wavelength shifts in the UV-vis absorption spectra. The flexibility of this approach was demonstrated as reactions were carried out using an array of different guest precursor salts and solvents with a range of polarities. Moreover, the reactions were generalizable among selenide and sulfide films and proceeded under milder conditions in comparison with reported nanocrystal reactions. A ligand-free environment with flexible reaction conditions, as the work herein, could aid in deconvoluting the different factors involved in CE reactions and further expand its use for fundamental research and applications like photovoltaics, optoelectronics, and catalysis.

Two-dimensional (2D) metal-halide perovskites have promising characteristics for optoelectronic applications. By incorporating Mn²⁺ ions into the perovskite structure, improved photoluminescence quantum yield can be achieved. This has been attributed to the formation of defect states that act as efficient recombination centers. Here, we make use of transient photoluminescence microscopy to characterize important material parameters of Mn²⁺-doped 2D perovskites with different doping levels. From these measurements, we visualize the importance of exciton transport as an intermediate step in the excitation of Mn²⁺. We model the spatiotemporal dynamics of the excited states to extract the diffusion constant and the transfer rate of the excitations to the Mn dopant sites. Interestingly, from these models, we find that the average distance an exciton needs to travel before transferring to a Mn site is significantly larger than expected from the Mn concentration obtained from elemental analysis. These insights are critical from a device design perspective.