Synthesis and conjugation of Sr2MgSi2O7:Eu2+, Dy3+ water soluble afterglow nanoparticles for photodynamic activation.

The applications of afterglow particles for photodynamic activation and biological imaging have become a topical research area. For these applications, it is critical to have water soluble nanoparticles. However, the synthesis of water soluble afterglow nanoparticles like Sr2MgSi2O7:Eu2+, Dy3+ is a challenging issue because most afterglow materials are very complicated in composition that cannot be synthesized by simple chemical routes. Here, for the first time, Sr2MgSi2O7:Eu2+, Dy3+ water soluble and stable nanoparticles are synthesize using a modified Sol-Gel method followed by the grinding and coating with APTES. The surface coating of the afterglow with APTES and the conjugation with PpIX and folic acid not only improve their water solubility but also enhance the PpIX luminescence by 10 times. More importantly, these strategies make it possible to produce singlet oxygen under X-ray irradiation, which is a very important result for deep cancer treatment. In addition, the surface coating and conjugation largely increase the cell uptake and greatly reduce their dark cytotoxicity. All these results indicate the methods reported here for afterglow nanoparticle synthesis, coating and conjugation are successful, and consequently, the prepared Sr2MgSi2O7:Eu2+, Dy3+/PPIX/Folic acid nano-conjugates are promising for X-ray induced photodynamic therapy on cancer treatment.

Luminescence- and nanoparticle-mediated increase of light absorption by photoreceptor cells: Converting UV light to visible light.

We developed new optic devices - singly-doped luminescence glasses and nanoparticle-coated lenses that convert UV light to visible light - for improvement of visual system functions. Tb(3+) or Eu(3+) singly-doped borate glasses or CdS-quantum dot (CdS-QD) coated lenses efficiently convert UV light to 542 nm or 613 nm wavelength narrow-band green or red light, or wide-spectrum white light, and thereby provide extra visible light to the eye. In zebrafish (wild-type larvae and adult control animals, retinal degeneration mutants, and light-induced photoreceptor cell degeneration models), the use of Tb(3+) or Eu(3+) doped luminescence glass or CdS-QD coated glass lenses provide additional visible light to the rod and cone photoreceptor cells, and thereby improve the visual system functions. The data provide proof-of-concept for the future development of optic devices for improvement of visual system functions in patients who suffer from photoreceptor cell degeneration or related retinal diseases.