Size-dependent Interactions between Au Nanoparticles and DNA in Electrochemical Oxidation and Fluorescence Quenching

Abstract

DNA서열에서 Guanine 염기를 포함하는 Single-stranded oligonucleotides는 DNA 염기의 hydrophobic interaction에 의해서 gold nanoparticle (AuNPs) 위에 흡착된다. DNA-AuNPs complex 존재 하에서 Ru(bpy)3 2+의 Cyclic voltammetry는 DNA 염기인 guanine의 산화 때문에 anodic current가 증가한다. 이 current enhancement는 single-stranded DNA (ssDNA)에만 해당하는 current보다 훨씬 작게 나타난다. 감소된 current는 AuNPs 위에 고정된 DNA의 Guanines에서 용매의 접근이 덜 되기 때문이라고 해석할 수 있다. 이렇게 점진적으로 감소되는 current는 single-stranded DNA에 AuNPs의 titration을 통해 AuNPs 위에 ssDNA가 binding되어 saturation point가 나타남에 따라 알 수 있다. 본 Chapter I 에서는 ssDNA와 AuNP 사이에 존재하는 interaction이 AuNPs의 size에 따라 어떻게 의존되는지, (상보적인 가닥과의 배양에 의한 AuNPs에서 ssDNA의 detachment) 해당되는 상보적인 가닥과의 배양에서 DNA-AuNP complex에서의 ssDNA 분리에 기초하여 연구하였다. Oligonucleotides는 5nm AuNPs보다 13nm와 30nm AuNPs에서 더 강하게 결합되었다. The pyridine nucleotides (NAD(P)H), Nicotinamide Adenine Dinucleotide (NAD)는 살아있는 유기체 내에서 biological electron transporters로 작용하는 흔한 물질이다. Nicotinamide coenzymes인 NADH의 재생은 Alcohols뿐만 아니라 aldehydes, acids, amines, phenols의 dehydrogenase-catalyzed oxidation에서 합성적으로 흥미롭고 중요한 역할을 한다. Ruthenium(II) complexes는 간단한 합성과정과 가시광선 영역의 빛을 강하게 흡수하는 특이한 광·물리적 성질, 유리한 산화환원 성질, 중요한 luminescence quantum yield, 적당한 excited state lifetime, 그리고 무엇보다도 특히 photostability 때문에 photosensitizers로 널리 쓰여져 왔다. Ru(II)-Rh(III) complex complex는 NADH 재생에 photocatalyst로 작용하는데, 감도가 좋고 효율이 높다. PDA-Ru(II) complex는 PDA의 화학적 감도특성과 Ru(II) complex의 광·물리적 성질을 같이 가지는 장점이 있다. PDA colorimetric으로 인해 반응조건을 쉽게 컨트롤 할 수 있다. NADH 재생 반응에서, PDARu(II) complex는 unmodified Ru(II) complex에 비해 매우 높은 효율을 보인다.;Single-stranded oligonucleotides containing guanine bases in their sequences were adsorbed onto gold nanoparticles (AuNPs) by a hydrophobic interaction of the bases of DNA with AuNPs. The cyclic voltammetry of Ru(bpy)3 2+(bpy =2,2’-bipyridine) in the presence of the DNA-AuNP complex afforded an anodic current enhancement due to the oxidation of the guanine bases of DNA. The current enhancement appeared much smaller than that obtained only with the corresponding single-stranded DNA (ssDNA). This current reduction is interpreted due to the less solvent accessibility of the guanines in DNA immobilized on AuNPs. The progressive current reduction was obtained in the titration of AuNPs to single-stranded DNA, affording a saturation point of the binding of ssDNA on AuNPs. The size dependence of AuNPs on the interaction between ssDNA and AuNP was studied based on the separation of ssDNA from the DNA-AuNP complex in incubation with the corresponding complementary strand. Oligonucleotides bound to 13 and 30 nm AuNPs had stronger binding strength than 5nm AuNPs. The pyridine nucleotides(NAD(P)H), Nicotinamide Adenine Dinucleotide (NAD+) is ubiquitous in all living systems serving as biological electron transporters. Regeneration of the nicotinamide coenzymes NADH, plays an important role for the synthetically interesting dehydrogenase-catalyzed oxidation of alcohols, aldehydes, acids, as well as amines and even phenols. Ruthenium(II) complexes have been widely used as photosensitizers because of their simple synthetic procedure and unique photophysical properties such as strong absorption in the visible region, favorable redox properties, significant luminescence quantum yield, moderate excited state lifetime and above all their photostability. Ru(II)-Rh(III) complex complex functions as a photocatalyst for generation NADH is sensitive and efficient. The pyridine nucleotides(NAD(P)H), Nicotinamide Adenine Dinucleotide (NAD+) is ubiquitous in all living systems serving as biological electron transporters. Regeneration of the nicotinamide coenzymes NADH, plays an important role for the synthetically interesting dehydrogenase-catalyzed oxidation of alcohols, aldehydes, acids, as well as amines and even phenols. Ruthenium(II) complexes have been widely used as photosensitizers because of their simple synthetic procedure and unique photophysical properties such as strong absorption in the visible region, favorable redox properties, significant luminescence quantum yield, moderate excited state lifetime and above all their photostability. Ru(II)-Rh(III) complex complex functions as a photocatalyst for generation NADH is sensitive and efficient.