Mediated Electron Transfer at Vertically Aligned Single-Walled Carbon Nanotube Electrodes During Detection of DNA Hybridization.
Mediated Electron Transfer at Vertically Aligned Single-Walled Carbon Nanotube Electrodes During Detection of DNA Hybridization.
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DOI：
10.1186/s11671-015-0978-0
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发表时间：
2015-12
影响因子：
--
通讯作者：
Bandyopadhyay K
中科院分区：
文献类型：
--
作者：
Wallen R;Gokarn N;Bercea P;Grzincic E;Bandyopadhyay K
在半胱胺和2-巯基乙醇（2-ME）官能化的金表面上，通过在酸缩短的单壁碳纳米管（SWCNT）末端产生的羧基与存在于金表面上的胺基之间形成酰胺键，产生垂直排列的单壁碳纳米管（VASWCNT）组装体。原子力显微镜（AFM）成像证实了垂直对齐模式的单壁碳纳米管附件通过显着的变化相比，裸露的金表面和缺乏任何水平对齐的单壁碳纳米管存在的表面粗糙度。这些单壁碳纳米管组件进一步修改与胺封端的单链探针DNA。随后，在溶液中存在互补链的情况下，使用Fe（CN）63−/4−作为溶液中的氧化还原探针的情况下的阻抗测量来跟踪表面结合的探针-DNA的杂交，其显示了由于杂交引起的界面电化学性质的变化，特别是电荷转移电阻。此外，探针-DNA的杂交也进行了比较，当它直接连接到金表面没有任何中间单壁碳纳米管。与我们的预期相反，阻抗测量显示电荷转移电阻随着时间的推移而降低，这是由于与300 nM互补DNA在溶液中的杂交，其中探针-DNA连接到单壁碳纳米管。相反，当探针DNA直接附着在金表面时，在杂交过程中观察到电荷转移电阻随时间的增加。在VASWCNT的存在下，在杂交过程中的电荷转移电阻的降低表明在VASWCNT修饰电极的氧化还原探针的电子转移过程中的增强。结果表明，VASWCNTs作为电子转移的介质，这有利于在电极-溶液界面的氧化还原探针的电荷转移。
Vertically aligned single-walled carbon nanotube (VASWCNT) assemblies are generated on cysteamine and 2-mercaptoethanol (2-ME)-functionalized gold surfaces through amide bond formation between carboxylic groups generated at the end of acid-shortened single-walled carbon nanotubes (SWCNTs) and amine groups present on the gold surfaces. Atomic force microscopy (AFM) imaging confirms the vertical alignment mode of SWCNT attachment through significant changes in surface roughness compared to bare gold surfaces and the lack of any horizontally aligned SWCNTs present. These SWCNT assemblies are further modified with an amine-terminated single-stranded probe-DNA. Subsequent hybridization of the surface-bound probe-DNA in the presence of complementary strands in solution is followed using impedance measurements in the presence of Fe(CN)63−/4− as the redox probe in solution, which show changes in the interfacial electrochemical properties, specifically the charge-transfer resistance, due to hybridization. In addition, hybridization of the probe-DNA is also compared when it is attached directly to the gold surfaces without any intermediary SWCNTs. Contrary to our expectations, impedance measurements show a decrease in charge-transfer resistance with time due to hybridization with 300 nM complementary DNA in solution with the probe-DNA attached to SWCNTs. In contrast, an increase in charge-transfer resistance is observed with time during hybridization when the probe-DNA is attached directly to the gold surfaces. The decrease in charge-transfer resistance during hybridization in the presence of VASWCNTs indicates an enhancement in the electron transfer process of the redox probe at the VASWCNT-modified electrode. The results suggest that VASWCNTs are acting as mediators of electron transfer, which facilitate the charge transfer of the redox probe at the electrode–solution interface.
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