Near Infrared Surface Plasmon Resonance Phase Imaging and Nanoparticle-Enhanced Surface Plasmon Resonance Phase Imaging for Ultrasensitive Protein and DNA Biosensing with Oligonucleotide and Aptamer M

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• 作者：Wen-Juan Zhou ; Aaron R. Halpern ; Ting H. Seefeld ; Robert M. Corn
• 刊名：Analytical Chemistry
• 出版年：2012
• 出版时间：January 3, 2012
• 年：2012
• 卷：84
• 期：1
• 页码：440-445
• 全文大小：321K
• 年卷期：v.84,no.1(January 3, 2012)
• ISSN：1520-6882

文摘

The techniques of surface plasmon resonance-phase imaging (SPR-PI) and nanoparticle-enhanced SPR-PI have been implemented for the multiplexed bioaffinity detection of proteins and nucleic acids. The SPR-PI experiments utilized a near-infrared 860 nm light emitting diode (LED) light source and a wedge depolarizer to create a phase grating on a four-element single-stranded DNA (ssDNA) microarray; bioaffinity adsorption onto the various microarray elements was detected via multiplexed real time phase shift measurements. In a first set of demonstration experiments, an ssDNA aptamer microarray was used to directly detect thrombin at concentrations down to 100 pM with SPR-PI. Two different ssDNA aptamers were used in these experiments with two different Langmuir adsorption coefficients, K_A1 = 4.4 脳 10⁸ M^鈥? and K_A2 = 1.2 脳 10⁸ M^鈥?. At concentrations below 1 nM, the equilibrium phase shifts observed upon thrombin adsorption vary linearly with concentration with a slope that is proportional to the appropriate Langmuir adsorption coefficient. The observed detection limit of 100 pM is approximately 20 times more sensitive than that observed previously with SPRI. In a second set of experiments, two short ssDNA oligonucleotides (38mers) were simultaneously detected at concentrations down to 25 fM using a three-sequence hybridization format that employed 120 nm DNA-modified silica nanoparticles to enhance the SPR-PI signal. In this first demonstration of nanoparticle-enhanced SPR-PI, the adsorbed silica nanoparticles provided a greatly enhanced phase shift upon bioaffinity adsorption due to a large increase in the real component of the interfacial refractive index from the adsorbed nanoparticle. As in the case of SPR-PI, the detection limit of 25 fM for nanoparticle-enhanced SPR-PI is approximately 20 times more sensitive than that observed previously with nanoparticle-enhanced SPRI.