Biomedical Engineering Center, College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, People's Republic of China.
Anal Chem. 2010 Jul 15;82(14):6308-14. doi: 10.1021/ac101018v.
Plasmonic metal nanoparticles (NPs) exhibit size, shape, and composition-dependent optical properties and have been studied extensively in the field of biosensing, but wide applications so far are limited by a lack of both highly sensitive and quantitative yet cost-effective optical detection schemes. We present a single molecule biosensing method based on color differentiation of scattered light between single plasmonic NPs and DNA hybridization-induced NP aggregates. With a seed-mediated NP growth method and a fast DNA modification method, highly stable, spectrally uniform and monodisperse Au NP (40 nm) and Au/Ag/Au composite NP (33 nm) probes were successfully prepared. Through theoretical calculations, single NP spectral measurements, and real time single-NP tracking experiments, we show that binding of a single target molecule between two NP probes can be recognized without separation from the unbound NPs by simply using a darkfield microscope equipped with a conventional light source and a color charge coupled device (CCD) camera. The detection limit of this homogeneous assay reached 0.02 pM. As an initial demonstration of multiplexed sensing at the single NP level, we used Au NPs and Au/Ag/Au composite NPs as different color probes. This scheme could be potentially applied to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.
等离子体金属纳米粒子（NPs）表现出尺寸、形状和组成依赖性的光学特性，在生物传感领域得到了广泛的研究，但迄今为止，由于缺乏高度敏感和定量且具有成本效益的光学检测方案，其广泛应用受到限制。我们提出了一种基于单个等离子体 NPs 之间散射光的颜色差异和 DNA 杂交诱导的 NP 聚集的单分子生物传感方法。通过种子介导的 NP 生长方法和快速的 DNA 修饰方法，成功制备了高度稳定、光谱均匀和单分散的 Au NP（40nm）和 Au/Ag/Au 复合 NP（33nm）探针。通过理论计算、单个 NP 光谱测量和实时单个-NP 跟踪实验，我们表明，通过使用配备常规光源和彩色电荷耦合器件（CCD）相机的暗场显微镜，无需从未结合的 NPs 中分离出来，就可以识别两个 NP 探针之间的单个靶分子的结合。这种均相测定的检测限达到了 0.02 pM。作为在单个 NP 水平上进行多重传感的初步演示，我们使用 Au NPs 和 Au/Ag/Au 复合 NPs 作为不同的颜色探针。该方案可能潜在地应用于其他领域，如多重免疫分析、单细胞分析和实时生物分子相互作用研究。
