MAENOSONO Laboratory
<Major Research Areas>Colloid Chemistry, Functional Materials Chemistry, Solid State Property, Chemical Engineering

Nanoparticle Technology:
From synthesis to practical applications

Research activity

　　Green chemistry methodology is used to reduce raw material consumption, waste, and hazardous substances through designing environmentally-friendly chemical reactions, and/or by controlling the higher-order structures of nanomaterials.
　　Our group fabricates new functional materials based on this perspective, with a focus on nanoparticles. Our two main research projects are as follows.

1Development of functional properties of colloidal semiconductor nanoparticles via higher-order structuring

　　Colloidal semiconductor nanoparticles (quantum dots: QDs) exhibit a strong quantum confinement effect and, thus, can be considered as “artificial atoms”. Therefore, the function of a QD ensemble is determined not only by the physicochemical properties of a single QD, but also by the inter-dot interactions that vary with their higher-order structure.
　　We synthesize QDs and their higher-order structures via a colloid chemical route, and investigate structure-property relations. Specifically, we aim to clarify inter-dot interactions in the higherorder structures of II-VI, III-V, and IV-VI semiconductor QDs. In addition, we hope to create QD solids capable of new functions based on inter-dot interactions, which are not observed in a single QD. At the same time, we aspire to develop the practical applications of QDs, such as LED, solar cell, and photodetector.

2Application of magnetic nanoparticles to biotechnology and environmental technology

　　In general, ferromagnetic materials only have ferromagnetic properties over a certain critical size. This is due to the disordering of magnetic moments becoming prominent, which is caused by thermal disturbance (superparamagnetism).
　　The area density of magnetic storage media increases with each passing year, and researchers have aimed at the realization of the density of Tbit･in-2. Magnetic nanoparticles (MNPs) have attracted attention and have been intensively investigated for this purpose. In magnetic storage media, one of the most important challenges is the fight against superparamagnetism.
　　However, the superparamagnetic nanoparticles are very important for medical applications, such as MRI contrast agents, magnetic immunodiagnostics, magnetic separation, and magnetic hyperthermia. Our research group concentrates on these applications of superparamagnetic nanoparticles. We synthesize MNPs, functionalize their surfaces, and develop basic techniques for medical and environmental applications.

Equipment

TEM, SEM, AFM, Fluorescence Spectrophotometer, UV-vis, FTIR, XRD, SQUID, CHN elemental analyzer.

The main research achievements in the past five years

1. I. Robinson, Le D. Tung, S. Maenosono, C. Wälti, and Nguyen T. K. Thanh, Gold coated magnetic nanoparticles: Interaction with thiolated DNA, Nanoscale, 2, 2624-2630 (2010)
2. D. Mott, Nguyen T. B. Thuy, Y. Aoki, and S. Maenosono, Aqueous synthesis and characterization of Ag and Ag@Au nanoparticles: Addressing challenges in size, monodispersity, and structure, Phil. Trans. R. Soc. A, 368, 4275-4292 (2010)
3. J. D. Lee and S. Maenosono, Field-induced control of universal fluorescence intermittency of a quantum dot light emitter, J. Chem. Phys., 133, 074703 (2010)
4. S. Nishimura, A. Takagaki, S. Maenosono, and K. Ebitani, In situ time-resolved XAFS study on the formation mechanism of Cu nanoparticles using poly(N-vinyl-2-pyrrolidone) as a capping agent, Langmuir, 26, 4473-4479 (2010)
5. Tran V. Thu and S. Maenosono, Synthesis of high-quality Al-doped ZnO nanoink, J. Appl. Phys., 107, 014308 (2010)