Division of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore.
Nanotechnology. 2011 Sep 30;22(39):395101. doi: 10.1088/0957-4484/22/39/395101. Epub 2011 Sep 2.
Upconversion nanoparticles (UCNs) are nanoparticles that are excited in the near infrared (NIR) region with emission in the visible or NIR regions. This makes these particles attractive for use in biological imaging as the NIR light can penetrate the tissue better with minimal absorption/scattering. This paper discusses the study of the depth to which cells can be imaged using these nanoparticles. UCNs with NaYF(4) nanocrystals doped with Yb(3+), Er(3+) (visible emission)/Yb(3+), Tm(3+) (NIR emission) were synthesized and modified with silica enabling their dispersion in water and conjugation of biomolecules to their surface. The size of the sample was characterized using transmission electron microscopy and the fluorescence measured using a fluorescence spectrometer at an excitation of 980 nm. Tissue phantoms were prepared by reported methods to mimic skin/muscle tissue and it was observed that the cells could be imaged up to a depth of 3 mm using the NIR emitting UCNs. Further, the depth of detection was evaluated for UCNs targeted to gap junctions formed between cardiac cells.
上转换纳米粒子（UCNs）是在近红外（NIR）区域被激发、在可见或近红外区域发射的纳米粒子。这使得这些粒子在生物成像中很有吸引力，因为近红外光可以更好地穿透组织，吸收/散射最小。本文讨论了使用这些纳米粒子对细胞进行成像的深度研究。合成了掺杂 Yb(3+)、Er(3+)（可见发射）/Yb(3+)、Tm(3+)（近红外发射）的 NaYF(4)纳米晶体的 UCNs，并进行了硅烷化修饰，使其在水中分散，并将生物分子共轭到其表面。使用透射电子显微镜对样品的尺寸进行了表征，并在 980nm 的激发下使用荧光光谱仪测量了荧光。通过报道的方法制备了组织仿体来模拟皮肤/肌肉组织，观察到可以使用发射近红外光的 UCNs 对深度达 3mm 的细胞进行成像。此外，还评估了针对心脏细胞之间形成的间隙连接的 UCNs 的检测深度。
