More Like this

1. Direct observation of the formation and stabilization of metallic nanoparticles on carbon supports

   https://doi.org/10.1038/s41467-020-20084-5  

   Huang, Zhennan; Yao, Yonggang; Pang, Zhenqian; Yuan, Yifei; Li, Tangyuan; He, Kun; Hu, Xiaobing; Cheng, Jian; Yao, Wentao; Liu, Yuzi; et al (December 2020, Nature Communications)

   null (Ed.)

   Abstract Direct formation of ultra-small nanoparticles on carbon supports by rapid high temperature synthesis method offers new opportunities for scalable nanomanufacturing and the synthesis of stable multi-elemental nanoparticles. However, the underlying mechanisms affecting the dispersion and stability of nanoparticles on the supports during high temperature processing remain enigmatic. In this work, we report the observation of metallic nanoparticles formation and stabilization on carbon supports through in situ Joule heating method. We find that the formation of metallic nanoparticles is associated with the simultaneous phase transition of amorphous carbon to a highly defective turbostratic graphite (T-graphite). Molecular dynamic (MD) simulations suggest that the defective T-graphite provide numerous nucleation sites for the nanoparticles to form. Furthermore, the nanoparticles partially intercalate and take root on edge planes, leading to high binding energy on support. This interaction between nanoparticles and T-graphite substrate strengthens the anchoring and provides excellent thermal stability to the nanoparticles. These findings provide mechanistic understanding of rapid high temperature synthesis of metal nanoparticles on carbon supports and the origin of their stability. 

   more » « less
2. The influence of the polyol solvents on the continuous growth of water-dispersible iron oxide nanoparticles

   https://doi.org/10.1557/s43578-023-01236-x  

   Qu, Jing; Cheah, Pohlee; Adams, Daniel; Collen, Charles; Zhao, Yongfeng (December 2023, Journal of Materials Research)

   Abstract Magnetic nanoparticles have continued to gain significant attention due to their unique magnetic properties and potential applications. However, it is still challenging to directly synthesize water-dispersible magnetic nanoparticles with controlled size for biomedical applications. This study investigates the influence of solvents on the continuous growth of magnetic nanoparticles, aiming to achieve controlled size and excellent water dispersibility via thermal decomposition in polyol solvents. The size of the nanoparticles gradually increases with longer polyol chain solvents. The increase in nanoparticles size is more significant under a higher reaction temperature (220 °C) compared to a lower temperature (190 °C). These monodispersed nanoparticles exhibit strong superparamagnetic properties, improving with longer solvent chain lengths at the same size. Magnetic resonance imaging (MRI) studies reveal higher relaxivities for magnetic nanoparticles synthesized in longer-chain polyols. This research offers valuable insights for synthesizing magnetic nanoparticles with precise sizes, magnetic properties, and biomedical applications. Graphical abstract 

   more » « less
3. Effective repulsive interaction between Janus polymer-grafted nanoparticles adhering to lipid vesicles

   https://doi.org/10.1063/5.0249522  

   Darling, Jordan F; Sharma, Abash; Zhu, Yu; Spangler, Eric J; Laradji, Mohamed (January 2025, The Journal of Chemical Physics)

   The adhesion of nanoparticles to lipid vesicles causes curvature deformations to the membrane to an extent determined by the competition between the adhesive interaction and the membrane’s elasticity. These deformations can extend over length scales larger than the size of a nanoparticle, leading to an effective membrane-curvature-mediated interaction between nanoparticles. Nanoparticles with uniform surfaces tend to aggregate into unidimensionally close-packed clusters at moderate adhesion strengths and endocytose at high adhesion strengths. Here, we show that the suppression of close-packed clustering and endocytosis can be achieved by the surface modification of the nanoparticles into Janus particles where a moiety of their surface is grafted with polymers under a good solvent condition. The osmotic pressure of the polymer brushes prevents membrane wrapping of the nanoparticles’ moieties that are grafted with polymers, thus suppressing their endocytosis. Furthermore, a repulsion between polymer brushes belonging to two nearby nanoparticles destabilizes the dimerization of the nanoparticles over a wide range of values of the polymers’ molecular weight and grafting density. This surface modification of nanoparticles should allow for reliable, non-close-packed, and tunable self-assemblies of nanoparticles. 

   more » « less
4. Synthesis of Biomimetic Melanin-Like Multifunctional Nanoparticles for pH Responsive Magnetic Resonance Imaging and Photothermal Therapy

   https://doi.org/10.3390/nano11082107  

   Qu, Jing; Guillory, Devin; Cheah, Pohlee; Tian, Bin; Zheng, Jie; Liu, Yongjian; Cates, Courtney; Janorkar, Amol V.; Zhao, Yongfeng (August 2021, Nanomaterials)

   The design and development of multifunctional nanoparticles have attracted great interest in biomedical research. This study aims to prepare pH-responsive melanin-like nanoparticles for T1-weighted magnetic resonance imaging (MRI) and photothermal therapy. The new multifunctional nanoparticles (amino-Fe-PDANPs) are synthesized by copolymerization of dopamine and its derivative amino-N-[2-(diethylamino) ethyl]-3,4-dihydroxy-benzenepropanamide (N-Dopa) at room temperature. The size of nanoparticles can be controlled by NaOH concentration. The incorporation of N-Dopa is characterized by NMR and FT-IR. From transmission electron microscopy (TEM), the nanoparticles exhibit excellent dispersion stability in water and are spherical in shape. The MRI measurement has demonstrated that amino-Fe-PDANPs have a significant signal enhancement in responding to the acidic solution. Confirmed by the photothermal study, the nanoparticles exhibit a high photothermal conversion efficiency. The melanin-like multifunctional nanoparticles integrate both diagnosis and therapeutic functionalities, indicating the potential for theranostic application. 

   more » « less
5. MnO, Co and Ni Nanoparticle Synthesis by Oleylamie and Oleic Acid

   https://doi.org/10.2174/2666001601666211110093947  

   He, Wencai; Qi, Yifang; Erugu, Uppalaiah; Moore, Jaiden; Zhu, Xianchun; Han, Fengxiang; Tang, Jinke; Dai, Qilin (May 2022, Current Chinese Chemistry)

   Background: Magnetic nanoparticles are attracting much attention toward easyoperation and size controllable synthesis methods. We develop a method to synthesize MnO, Co,CoO, and Ni nanoparticles by thermal decomposition of metal 2,4-pentanedionates in the presenceof oleylamine (OLA), oleic acid (OA), and 1-octadecene (ODE). Methods: Similar experimental conditions are used to prepare nanoparticles except for the metalstarting materials (manganese 2,4-pentanedionate, nickel 2,4-pentanedionate, and cobalt 2,4-pentanedionate), leading to different products. For the manganese 2,4-pentanedionate startingmaterial, MnO nanoparticles are always obtained as the reaction is controlled with differenttemperatures, precursor concentrations, ligand ratios, and reaction time. For the cobalt 2,4-pentanedionate starting material, only three experimental conditions can produce pure phase CoOand Co nanoparticles. For the nickel 2,4-pentanedionate starting material, only three experimentalconditions lead to the production of pure phase Ni nanoparticles. Results: The nanoparticle sizes increase with the increase of reaction temperatures. It is observedthat the reaction time affects nanoparticle growth. The nanoparticles are studied by XRD, TEM,and magnetic measurements. Conclusion: This work presents a facile method to prepare nanoparticles with different sizes,which provides a fundamental understanding of nanoparticle growth in solution. 

   more » « less