• Investigation, design and development of a fluorescence correlation spectroscopy system (FCS) with an inverted microscope configuration using high numerical aperture microscope objective; excitation: CW laser pumped by diode laser or picosecond diode laser.

• Measurement of the following targets using the home-made FCS system:

- FCS curves for single fluorescent dye molecule, characteristic parameters of the system and dynamics parameters for dye molecule such as diffusion time from the FCS curves.
- Characterizing intermolecular interaction of single biological molecules (DNA).

Theoretical results
Applied results

• 01 complete FCS system with low-cost excitation laser and microscope objective and a home-made detector satisfying the requirement of detecting signals from single molecule. Besides, some important optic components have been designed and made such as high precision micrometer stage.
• A complete layout for FCS system.
• FCS data for the following:

- Single dye molecule Rhodamine B and Rhodamine 6G, characteristic parameters for the FCS system (dimensions, volume of the observation volume) and diffusion time of the dye molecules obtained from FCS curves.
- Intermolecular interactions between DNA oligonucleotides.
Besides, we also applied the home-made FCS system to measure FCS for the following:
- Rhodamine B doped silica nanoparticles.
- Rhodamine B dye in the solutions of different viscosity.

• Premilinary measurement data for CdTe/CdS quantum dot (in collaboration with Institute of Materials Science, Vietnam Academy of Science and Technology).

• This is the first FCS system developed in Vietnam.
• The project presents for the first time the measurement data for single molecule/single nanoparticle in Vietnam.

Scientific papers in referred journals (list)

1. Nguyen T. Thanh Bao, Dinh Van Trung, Nguyen Thanh Binh, Nguyen Dinh Hoang, Phung Viet Tiep, Dao Duy Thang and Vu Thi Bich (2011). Building a fluorescence correlation spectroscopy system for single fluorescent nanoparticle. Advances in Optics Photonics Spectroscopy and Applications VI, Publishing House for Science and Technology, Phillippe Brechignac et al (eds). ISSN 1859-4271, p. 431.
2. Nguyen Thi Thanh Bao, Dinh Van Trung, Nguyen Thanh Binh (2012). Measuring single molecule diffusion time using fluorescence correlation spectroscopy. The 7^th National Conference on Optics and Spectroscopy, Ho Chi Minh city, Vietnam 26-29/11/2012.

Technological products (describe in details: technical characteristics, place)

• One FCS system at Room 35, 2H building, Center for Quantum Electronics, Institute of Physics, VAST.
• FCS system layout presented in the final project report.
• FCS data presented in the final project report for the following targets: fluorescent nanoparticles, dye molecules in water, characteristic parameters of FCS system, dye molecules in solutions of different viscosity, quantum dots.
• Contribution to master program with 01 master of science graduated.

The project can be continued to upgrade the home-made FCS system and to support domestic scientific community for having high-level reaseach and scientific papers of international standards.