The great scallop (Pecten maximus) reveals details about the uptake of nanoplastics by marine organisms. Microplastics are present in marine environments worldwide. As these particles break down further, they form nanoplastics, which are harder to detect. Nanoplastics also can enter the environment directly from commercial products such as paints and cosmetics. Al-Sid-Cheikh et al. investigate the uptake of such nanoplastics by scallops at predicted environmental concentrations.
X-Ray Imaging Coherent diffraction imaging with x-rays is a powerful characterization technique for nanoparticles. Piecing together the two-dimensional Bragg diffraction patterns through slices of the sample provides a three-dimensional picture of the structure and strain. However, for nanoparticles, the x-ray beam can induce mechanical instabilities in the sample; the rotation, rocking, and rolling that occur tend to limit the resolution of the information obtained. Björling et al. adapted a diffractive volume assembly algorithm that mitigates for the uncontrolled mechanical instabilities and demonstrate that it can be used to reconstruct sharper images of shape-controlled 60-nanometer-sized gold nanoparticles. Phys. Rev. Lett. 125 , 246101 (2020).
Complementary DNA strands can be used to assemble nanoparticles through specific connections, but creating multivalent directional connections is still challenging. Xiong et al. used DNA origami--a two-dimensional open square and a three-dimensional tetrahedron framework--to position DNA linkers on nanoparticles. These molecular stamping, or MOST, frames were "inked" with single-stranded DNA that transferred onto a gold nanoparticle bound inside the frame. On release, the particles could then undergo complementary strand binding with smaller gold nanoparticles to form clusters. By using different inks within the frame, gold particles of different sizes could be assembled onto the central particle.
Nanomaterials that form as heterostructures have applications in catalysis, plasmonics, and electronics. We explored how palladium-tin alloys form mixed-composition phases with metals with known but complex miscibilities. Nanoparticles with up to seven elements were synthesized, and many form triphase heterostructures consisting of either three-interface or two-interface architectures. Density functional theory calculations and experimental work were used to determine the balance between the surface and interfacial energies of the observed phases. From these observations, design rules have been established for making polyelemental systems with specific heterostructures, including tetraphase nanoparticles with as many as six junctions.
Specialized nanoparticles can be used for a variety of cloaking techniques as well as reflective surfaces. The development of these nanoparticles has been used from everything from troop operations to providing light scattering properties that can reduce heat and control design in our world. MIT researchers are now using computer modeling to design particles more thoroughly and improve their light scattering behaviors. Multilayered nanoparticles could be of use in biomedical devices, future displays and cloaking systems within the future. Using neural networks to examine the structure of nanoparticles and then simulate the way that it scatters along different colors of light can cut down on the expensive development and improve efficiency.