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   https://doi.org/10.3791/62176  

   Marrs, Jonathan; Ghomian, Taher; Domulevicz, Lucas; McCold, Cliff; Hihath, Joshua (January 2021, Journal of Visualized Experiments)

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2. Diminishing Interfacial Effects with Decreasing Nanoparticle Size in Polymer-Nanoparticle Composites

   https://doi.org/10.1103/PhysRevLett.121.207801  

   Emamy, Hamed; Kumar, Sanat K.; Starr, Francis W. (November 2018, Physical Review Letters)
3. Actuating superparamagnetic nanoparticle monolayers

   https://doi.org/10.1073/pnas.2424073122  

   Esposito, Edward_P; Lopez_Rios, Hector_Manuel; Olvera_de_la_Cruz, Monica; Jaeger, Heinrich_M (March 2025, Proceedings of the National Academy of Sciences)

   Magnetically responsive, mechanically flexible microstructures are desirable for applications ranging from smart sensors to remote-controlled actuation for surgery or robotics. Embedding magnetic nanoparticles into a thin matrix of elastic material enables high flexibility while exploiting the magnetic response of the individual particles. However, in the ultrathin limit of such nanocomposite materials, the particles become too small to sustain a permanent dipole moment. This implies that now large magnetic field gradients are required for actuation, which are difficult to achieve with externally applied fields. Here, we demonstrate through experiment and simulation that monolayer sheets of close-packed paramagnetic nanoparticles in a uniform applied field can generate large local field gradients through particle interactions. As a result, a strong collective magnetization is obtained that leads to large deflections of freestanding sheets already in moderate applied fields. Exploiting the vector nature of the applied field, we furthermore find that it is possible to induce more complex curvature and twist the sheets. Finally, we show that paramagnetic nanoparticle monolayers applied as coatings can generate sufficient force to deflect strips of nonmagnetic material that is several orders of magnitude thicker. 

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4. Crystallization‐driven Nanoparticle Crystalsomes

   https://doi.org/10.1002/anie.202217267  

   Gao, Lingfeng; Mei, Shan; Qian, Qian; Yu, Shichen; Zhao, Bin; Tu, Yingfeng; Li, Christopher Y. (February 2023, Angewandte Chemie International Edition)

   Abstract Nanoparticle (NP) assembly has been extensively studied, and a library of NP superstructures has been synthesized. These intricate structures show unique collective optical, electronic, and magnetic properties. In this work, we report a bottom‐up approach for fabricating spherical gold nanoparticle (AuNP) assemblies that mimic colloidosomes. Co‐crystallization of lipoic acid‐end‐functionalized poly(ethylene oxide) (PEO) and AuNPs in solution via a self‐seeding method led to the formation of hollow spherical NP assemblies named nanoparticle crystalsomes (NPCs). Due to the spherical shape, the translational symmetry of PEO crystals is broken in NPCs, which can be attributed to the competition between NP close packing and polymer crystallization. This was confirmed by tuning the NPC morphology via varying the self‐seeding temperature, crystallization temperature, and PEO molecular weight. We envisage that this strategy paves the way to attaining exquisite morphological control of NP assemblies with broken translational symmetry. 

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5. Nanoparticle tracking analysis and statistical mixture distribution analysis to quantify nanoparticle–vesicle binding

   https://doi.org/10.1016/j.jcis.2022.01.141  

   Foreman-Ortiz, Isabel U.; Fung Ma, Ting; Hoover, Brandon M.; Wu, Meng; Murphy, Catherine J.; Murphy, Regina M.; Pedersen, Joel A. (June 2022, Journal of Colloid and Interface Science)