A novel method for modifying the surface of magnetic‐resonance‐contrasting layered gadolinium hydroxide (LGdH) is developed providing them with water‐ and bio‐compatibility and acid‐resistance, all of which are essential for medical applications. A stable colloid of exfoliated layers is synthesized by exchanging interlayer anions of LGdH with oleate ions. The delaminated layers are successively coated with phospholipids with poly(ethylene glycol) tail groups, and their effectiveness as a contrast agent for magnetic resonance imaging (MRI) is demonstrated. The adaptability of this surface modification approach for incorporating functional molecules and fabricating a fluorescent colloid of LGdH, which has the potential utility as a multimodal probe, is also demonstrated. This result provides a novel approach for expanding the applications of layered inorganic materials and developing a new class of MRI contrast agents.

Annealing multilayers of gadolinium hydroxide lead to the growth of gadolinium oxychloride crystallites film through a two‐dimensionally confined process. The employment of confined crystallization process create a multilayer film composed of mixed crystallites each doped with different activator ions, such as Eu3+ and Tb3+, which demonstrates a novel method of fabricating robust and semi‐transparent inorganic thin films with multicolor emission capacity and color tunability.

The delaminated gadolinium hydroxide layers doped with Eu(3+) ions were assembled on the surface of silica spheres and annealed at high temperatures, resulting in the formation of fluorescent and MR active GdPO(4) : Eu nanoparticles at the surface.

The synthesis of a new stable colloid of fl uorescent LGdH layers through a newly developed surface modifi cation method is reported by Y.-s. Yoon et al. This new method involves layer exfoliation, anion exchange, and PEG coating. The effi cient MRI contrastenhancement of these LGdH layers, both in vitro and in vivo, demonstrates their potential utility as a multimodal probe combining optical and MR imaging.