Molecular Electronics Laboratory, Department of Bioelectronics and Biosensors, Science Campus, Alagappa University, Karaikudi 630003, India; Department of Industrial Chemistry, Alagappa University, Karaikudi 630003, India.
Centre for Nanoscience and Nanotechnology, Department of Chemistry, The Gandhigram Rural Institute, Gandhigram 624302, Tamil Nadu, India.
Biosens Bioelectron. 2019 May 15;133:48-54. doi: 10.1016/j.bios.2019.03.027. Epub 2019 Mar 15.
Carbon dots have been extensively used for the development of fluorescent based molecular affinity sensors. However, label free DNA sensing by electrochemical method is not reported so far. Herein, we report carbon dots stabilized silver nanoparticles (CD-AgNPs) lipid nano hybrids as a sensitive and selective platform for label free electrochemical DNA sensing. The CD-AgNPs were synthesized by wet chemical method and then characterized by UV-visible, Fourier-transform Infra-red (FT-IR), dynamic light scattering (DLS) and high resolution transmission electron microscopy (HR-TEM) techniques. These CD-AgNPs were used for decorating the binary lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) surface (named as lipid) and tethered on self-assembled monolayer of 3-mercaptopropionic acid (MPA) (MPA-lipid-CD-AgNPs). The formation of array of MPA-lipid-CD-AgNPs on Au electrode was confirmed by atomic force microscopy (AFM). Electrochemical behavior of MPA- lipid-CD-AgNPs was monitored in the presence of 1 mM potassium ferri/ferrocyanide (K/K [Fe(CN)]). The formation of layer-by-layer MPA-lipid-CD-AgNPs is indicated by increased anodic and cathodic peak (ΔE) separation with decreased redox peak current of K/K [Fe(CN)]. Short chain DNA (30 mer oligonucleotide, representing the lung cancer) was used as a model system for label free DNA sensing. Un-hybridized (single stranded DNA), hybridized (complementary hybridized), single, double and triple base mismatched target DNA hybridized surfaces were efficiently discriminated at 1 µM target DNA concentration at the Au/MPA-lipid-CD-AgNPs electrode by change in the charge transfer resistance from impedance technique. Further, the modified electrode was successfully used to determine target DNA in a wide linear range from 10 to 10 M. The present work open doors for the utilization of CDs in molecular affinity based electrochemical sensor design and development.
碳点已被广泛用于荧光分子亲和传感器的开发。然而，迄今为止，尚未有通过电化学方法进行无标记 DNA 传感的报道。在此，我们报告了碳点稳定的银纳米粒子（CD-AgNPs）脂质纳米杂化体作为一种灵敏和选择性的无标记电化学 DNA 传感平台。CD-AgNPs 通过湿化学法合成，然后通过紫外-可见分光光度法、傅里叶变换红外光谱（FT-IR）、动态光散射（DLS）和高分辨率透射电子显微镜（HR-TEM）技术进行表征。这些 CD-AgNPs 用于修饰二元脂质 1,2-二油酰基-sn-甘油-3-磷酸乙醇胺（DOPE）和 N-[1-(2,3-二油酰氧基)丙基]-N,N,N-三甲基氯化铵（DOTAP）表面（命名为脂质）并连接到自组装的巯基丙酸（MPA）单层上（MPA-脂质-CD-AgNPs）。原子力显微镜（AFM）证实了金电极上 MPA-脂质-CD-AgNPs 阵列的形成。在存在 1 mM 铁氰化钾/亚铁氰化钾（K/K [Fe(CN)]）的情况下监测 MPA-脂质-CD-AgNPs 的电化学行为。层状 MPA-脂质-CD-AgNPs 的形成表现为增加的阳极和阴极峰（ΔE）分离，同时减少 K/K [Fe(CN)]的氧化还原峰电流。短链 DNA（30 个核苷酸，代表肺癌）被用作无标记 DNA 传感的模型系统。在 Au/MPA-脂质-CD-AgNPs 电极上，在 1 µM 靶 DNA 浓度下，未杂交（单链 DNA）、杂交（互补杂交）、单、双和三碱基错配靶 DNA 杂交表面通过阻抗技术的电荷转移电阻变化得到有效区分。此外，该修饰电极还成功地用于在 10 至 10 M 的宽线性范围内测定靶 DNA。本工作为基于碳点的分子亲和力电化学传感器设计和开发开辟了道路。
