奈米粒子之尺寸介於數奈米至數百奈米之間，致使其量子侷限效應已成為不可忽視的因素，其理、化特性亦與一般塊材有著截然不同的改變。這些特性的改變使得奈米粒子之應用性大為增加。經結合物理、化學、生物及光電工程等科技，開啟了奈米粒子在生物醫學上分子層級的偵測、診斷及治療之應用。本文將簡介奈米粒子在生醫檢測、基因與藥物載體和光動力療法的應用原理，及現今常用之奈米粒子特性。最後討論各種奈米粒子所遇到之瓶頸及未來的發展。

The diameter of nanoparticles varies from few nanometer to hundred nanometers. Within this scale, the quantum confinement effects are dominant and they can not be ignored. Therefore, their physical and chemical properties are different from the block material. These intrinsic properties change of nanoparticles make them fit in many applications. By integrating the techniques of physics, chemistry, biology and electro-photonic technology with nanotechnology, these nanoparticles can be used in bio-medical monitoring, diagnosis and therapy in molecular level. In this article we introduce the principles of biomedical detection, gene/drug carrier and chemical/physical photo dynamic therapy (PDT) briefly. Meanwhile, the characteristics of nanoparticles are introduced. Finally, the limitation of these particles and their possible application in the near further are discussed.