We describe and demonstrate a general strategy for engineering binary and ternary hybrid nanoparticles based on spontaneous epitaxial nucleation and growth of a second and third component onto seed nanoparticles in high-temperature organic solutions. Multifunctional hybrid nanoparticles that combine magnetic, plasmonic, and semiconducting properties and that are tunable in size and morphology can be realized, as demonstrated for combinations of Au, Fe3O4 and PbS or PbSe. The properties of each component within the hybrids can be modulated strongly by the conjugating component(s) aided by the coherent interfaces between them.

Articular cartilage repair remains a great challenge for clinicians and researchers. Recently, there emerges a promising way to achieve one-step cartilage repair in situ by combining endogenic bone marrow stem cells (BMSCs) with suitable biomaterials using a tissue engineering technique. To meet the increasing demand for cartilage tissue engineering, a structurally and functionally optimized scaffold is designed, by integrating silk fibroin with gelatin in combination with BMSC-specific-affinity peptide using 3D printing (3DP) technology. The combination ratio of silk fibroin and gelatin greatly balances the mechanical properties and degradation rate to match the newly formed cartilage. This dually optimized scaffold has shown superior performance for cartilage repair in a knee joint because it not only retains adequate BMSCs, due to efficient recruiting ability, and acts as a physical barrier for blood clots, but also provides a mechanical protection before neocartilage formation and a suitable 3D microenvironment for BMSC proliferation, differentiation, and extracellular matrix production. It appears to be a promising biomaterial for knee cartilage repair and is worthy of further investigation in large animal studies and preclinical applications. Beyond knee cartilage, this dually optimized scaffold may also serve as an ideal biomaterial for the regeneration of other joint cartilages.

A method is presented for synthesizing core-shell structures consisting of monodisperse polystyrene latex nanospheres as cores and gold nanoparticles as shells. Use of polystyrene spheres as the core in these structures is advantageous because they are readily available commercially in a wide range of sizes, and with dyes or other molecules doped into them. Gold nanoparticles, ranging in size from 1 to 20 nm, are prepared by reduction of a gold precursor with sodium citrate or tetrakis(hydroxymethyl)phosphonium chloride (THPC). Carboxylate-terminated polystyrene spheres are functionalized with 2-aminoethanethiol hydrochloride (AET), which forms a peptide bond with carboxylic acid groups on their surface, resulting in a thiol-terminated surface. Gold nanoparticles then bind to the thiol groups to provide up to about 50% coverage of the surface. These nanoparticles serve as seeds for growth of a continuous gold shell by reduction of additional gold precursor. The shell thickness and roughness can be controlled by the size of the nanoparticle seeds as well as by the process of their growth into a continuous shell. By variation of the relative sizes of the latex core and the thickness of the gold overlayer, the plasmon resonance of the nanoshell can be tuned to specific wavelengths across the visible and infrared range of the electromagnetic spectrum, for applications ranging from the construction of photonic crystals to biophotonics. The position and width of the plasmon resonance extinction peak are well-predicted by extended Mie scattering theory.

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