Quantitative Photophysics of Photoluminescent and Scintillating Nanoparticles

量子点（QDs）是半导体材料（如硒化镉，CdSe）的荧光晶体，直径范围从~ 2到5nm。这还不到一个典型活细胞直径的千分之一。量子点被活性分子覆盖，使它们在水或其他溶液中保持稳定的悬浮状态。量子点的能量和反应性——由材料、封盖剂和大小决定——决定了量子点向溶液中其他分子转移电子或接受电子的能力。这种电子转移对于各种各样的应用和问题是非常重要的。不必要的电子转移会损害或杀死生物组织。由于它发生在纳米尺度上，损伤可能发生在细胞深处，包括细胞核。另一方面，电子转移可以用来杀死不需要的细胞，如癌细胞或细菌。将电子从量子点转移到其他材料也允许量子点用作太阳能电池的材料，尽管目前对该过程的了解还不够充分，无法创造出高效的材料。

Quantum dots (QDs) are fluorescent crystals of semiconductor materials (such as cadmium selenide, CdSe) that range from ~ 2 to 5 nm in diameter. This is less than 1/1000th the diameter of a typical living cell. QDs are capped with active molecules that enable them to remain in a stable suspension in water or other solutions. The energy and reactivity of QDs--determined by the material, capping agent, and size--determine the ability of a QD to transfer electrons to, or accept electrons from, other molecules in the solution. This electron transfer is very important for a large variety of applications and problems. Unwanted electron transfer can damage or kill biological tissue. Since it happens on the nanoscale, damage can occur deep inside cells, including the nucleus. On the other hand, electron transfer can be used to kill unwanted cells, such as cancer cells or bacteria. Transferring of electrons from QDs to other materials also allows QDs to be used as materials for solar cells, although currently the process is not well-enough understood to create high-efficiency materials.