Surface plasmon resonance sensing of nucleic acids: A review

Biosensors based on surface plasmon resonance (SPR) have become a central tool for the investigation and quantification of biomolecules and their interactions. Nucleic acids (NAs) play a vital role in numerous biological processes and therefore have been one of the major groups of biomolecules targeted by the SPR biosensors. This paper discusses the advances of NA SPR biosensor technology and reviews its applications both in the research of molecular interactions involving NAs (NA–NA, NA–protein, NA–small molecule), as well as for the field of bioanalytics in the areas of food safety, medical diagnosis and environmental monitoring.     

Surface plasmon resonance

During last decade there has been significant progress in the development of analytical techniques for evaluation of receptor-ligand iteraction. Surface plasmon resonance (SPR)-based optical biosensors are now being used extensively to defined the kinetics of wide variety of macromolecular interactions and high- and low-affinity small molecule interactions. The experimental design data analysis methods are evolving along with widespread applications in ligand fishing, microbiology, virology, host-pathogen interaction, epitope mapping and protein-, cell-, membrane-, nucleic acid-protein interactions. SPR based biosensors have strong impact on basic and applied research significantly. This brief review describes the SPR technology and few of its applications in relation to receptor-ligand interaction that has brought significant change in the methodology, analysis, interpretation, and application of the SPR technology.     

Selective High‐Resolution Detection of Membrane Protein–Ligand Interaction in Native Membranes Using Trityl–Nitroxide PELDOR

The orchestrated interaction of transmembrane proteins with other molecules mediates several crucial biological processes. Detergent solubilization may significantly alter or even abolish such hetero‐oligomeric interactions, which makes observing them at high resolution in their native environment technically challenging. Dipolar electron paramagnetic resonance (EPR) techniques such as pulsed electro–electron double resonance (PELDOR) can provide very precise distances within biomolecules. To concurrently determine the inter‐subunit interaction and the intra‐subunit conformational changes in hetero‐oligomeric complexes, a combination of different spin labels is required. Orthogonal spin labeling using a triarylmethyl (TAM) label in combination with a nitroxide label is used to detect protein–ligand interactions in native lipid bilayers. This approach provides a higher sensitivity and total selectivity and will greatly facilitate the investigation of multimeric transmembrane complexes employing different spin labels in the native lipid environment.     

Application of surface plasmon resonance for the detection of carbohydrates,glycoconjugates, and measurement of the carbohydrate-specific interactions: A comparison with conventional analytical techniques. A critical review

Carbohydrates (glycans) and their conjugates with proteins and lipids contribute significantly to many biological processes. That makes these compounds important targets to be detected, monitored and identified. The identification of the carbohydrate content in their conjugates with proteins and lipids (glycoforms) is often a challenging task. Most of the conventional instrumental analytical techniques are time-consuming and require tedious sample pretreatment and utilising various labeling agents. Surface plasmon resonance (SPR) has been intensively developed during last two decades and has received the increasing attention for different applications, from the real-time monitoring of affinity bindings to biosensors. SPR does not require any labels and is capable of direct measurement of biospecific interaction occurring on the sensing surface. This review provides a critical comparison of modern analytical instrumental techniques with SPR in terms of their analytical capabilities to detect carbohydrates, their conjugates with proteins and lipids and to study the carbohydrate-specific bindings. A few selected examples of the SPR approaches developed during 2004–2011 for the biosensing of glycoforms and for glycan–protein affinity studies are comprehensively discussed.     

Plasmon resonance methods in GPCR signaling and other membrane events

The existence of surface guided electromagnetic waves has been theoretically predicted from Maxwell's equations and investigated during the first decades of the 20th century. However, it is only since the late 1960's that they have attracted the interest of surface physicists and earned the moniker of "surface plasmon". With the advent of commercially available instruments and well established theories, the technique has been used to study a wide variety of biochemical and biotechnological phenomena. Spectral response of the resonance condition serves as a sensitive indicator of the optical properties of thin films immobilized within a wavelength of the surface. This enhanced surface sensitivity has provided a boon to the surface sciences, and fosters collaboration between surface chemistry, physics and the ongoing biological and biotechnological revolution. Since then, techniques based on surface plasmons such as Surface Plasmon Resonance (SPR), SPR Imaging, Plasmon Waveguide Resonance (PWR) and others, have been increasingly used to determine the affinity and kinetics of a wide variety of real time molecular interactions such as protein-protein, lipid-protein and ligand-protein, without the need for a molecular tag or label. The physical-chemical methodologies used to immobilize membranes at the surface of these optical devices are reviewed, pointing out advantages and limitations of each method. The paper serves to summarize both historical and more recent developments of these technologies for investigating structure-function aspects of these molecular interactions, and regulation of specific events in signal transduction by G-protein coupled receptors (GPCRs).     

Present and future of surface plasmon resonance biosensors

Surface plasmon resonance (SPR) biosensors are optical sensors exploiting special electromagnetic waves—surface plasmon-polaritons—to probe interactions between an analyte in solution and a biomolecular recognition element immobilized on the SPR sensor surface. Major application areas include detection of biological analytes and analysis of biomolecular interactions where SPR biosensors provide benefits of label-free real-time analytical technology. This paper reviews fundamentals of SPR affinity biosensors and discusses recent advances in development and applications of SPR biosensors.     

分子印迹表面等离子共振传感器在食品安全检测中的最新研究进展

分子印迹聚合物具有空间结构选择性高、稳定性好和制备过程简单等特点,结合表面等离子共振传感器,可用于分子间相互作用和结合特性的研究。随着石墨烯、量子点等纳米材料的出现和广泛应用,基于分子印迹技术的表面等离子共振传感器的灵敏度获得了改善,促进了该技术在食品安全检测领域的快速发展。该文基于分子印迹技术简要介绍了表面等离子共振传感器芯片的制备技术、分析体系及其优点,重点分析了国内外将分子印迹-表面等离子共振传感器用于食品安全检测的最新研究成果,阐释了分子印迹-表面等离子共振技术的优势,并展望了该技术在食品安全分析领域的发展趋势。     

Molecular Dynamics Simulation of Small Molecules Interacting with Biological Membranes

Cell membranes protect and compartmentalise cells and their organelles. The semi-permeable nature of these membranes controls the exchange of solutes across their structure. Characterising the interaction of small molecules with biological membranes is critical to understanding of physiological processes, drug action and permeation, and many biotechnological applications. This review provides an overview of how molecular simulations are used to study the interaction of small molecules with biological membranes, with a particular focus on the interactions of water, organic compounds, drugs and short peptides with models of plasma cell membrane and stratum corneum lipid bilayers. This review will not delve on other types of membranes which might have different composition and arrangement, such as thylakoid or mitochondrial membranes. The application of unbiased molecular dynamics simulations and enhanced sampling methods such as umbrella sampling, metadynamics and replica exchange are described using key examples. This review demonstrates how state-of-the-art molecular simulations have been used successfully to describe the mechanism of binding and permeation of small molecules with biological membranes, as well as associated changes to the structure and dynamics of these membranes. The review concludes with an outlook on future directions in this field.     

表面等离子体共振光谱技术与电化学方法联用及其应用

表面等离子体共振（Surface Plasmon Resonance,SPR）技术是利用金属薄膜光学耦合产生的物理光学现象建立的一种非常灵敏的光学分析手段. 近年发展的电化学表面等离子体共振（Electrochemical Surface Plasmon Resonance,EC-SPR）是将时间分辨表面等离子体共振光谱技术与电化学方法联用的一种新技术. 本文介绍了SPR和EC-SPR的基本原理,并重点阐述了时间分辨SPR光谱技术与电化学方法联用及应用,该技术已广泛地应用于反应动态过程研究、生物化学传感器、电极/溶液界面的表征、动力学常数的测定以及生物分子相互作用等领域.     

An optical surface plasmon resonance biosensor for determination of tetanus toxin

Surface plasmon resonance (SPR) has been successfully applied for the simple, rapid, and label-free assay of various biomolecules. This assay evaluates a novel wavelength modulation SPR biosensor for the detection of tetanus toxin. The wavelength modulation SPR biosensor is designed based on fixing the incident angle of light and measuring the reflected intensities in the resonance wavelength range spanning 400-800 nm simultaneously. Tetanus toxin (TeNT), one of the most potent toxins known, is synthesized as a 150 kDa single polypeptide chain. The SPR biosensor has been shown to be capable of directly detecting concentration of tetanus toxin as low as 0.028 Lf ml⁻¹. Under selected experimental conditions, the SPR biosensor has a good reproducibility, sensitivity and reversibility. The results illustrate how wavelength modulation SPR biosensor can be used to detect biomolecular interactions.     

Characterization and Application of Supramolecular Junctions

The convergence of supramolecular chemistry and single-molecule electronics offers a new perspective on supramolecular electronics, and provides a new avenue toward understanding and application of intermolecular charge transport at the molecular level. In this review, we will provide an overview of the advances in the characterization technique for the investigation of intermolecular charge transport, and summarize the experimental investigation of several non-covalent interactions, including π-π stacking interactions, hydrogen bonding, host-guest interactions and σ-σ interactions at the single-molecule level. We will also provide a perspective on supramolecular electronics and discuss the potential applications and future challenges.     

Recent advances in surface plasmon resonance based techniques for bioanalysis

Surface plasmon resonance (SPR) is a powerful and versatile spectroscopic method for biomolecular interaction analysis (BIA) and has been well reviewed in previous years. This updated 2006 review of SPR, SPR spectroscopy, and SPR imaging explores cutting-edge technology with a focus on material, method, and instrument development. A number of recent SPR developments and interesting applications for bioanalysis are provided. Three focus topics are discussed in more detail to exemplify recent progress. They include surface plasmon fluorescence spectroscopy, nanoscale glassification of SPR substrates, and enzymatic amplification in SPR imaging. Through these examples it is clear to us that the development of SPR-based methods continues to grow, while the applications continue to diversify. Major trends appear to be present in the development of combined techniques, use of new materials, and development of new methodologies. Together, these works constitute a major thrust that could eventually make SPR a common tool for surface interaction analysis and biosensing. The future outlook for SPR and SPR-associated BIA studies, in our opinion, is very bright. Surface plasmon resonance (SPR) is a powerful and versatile spectroscopic method for biomolecular interaction analysis (BIA) and has been well reviewed in previous years. This updated 2006 review of SPR, SPR spectroscopy, and SPR imaging explores cutting-edge technology with a focus on material, method, and instrument development. A number of recent SPR developments and interesting applications for bioanalysis are provided. Three focus topics are discussed in more detail to exemplify recent progress. They include surface plasmon fluorescence spectroscopy, nanoscale glassification of SPR substrates, and enzymatic amplification in SPR imaging. Through these examples it is clear to us that the development of SPR-based methods continues to grow, while the applications continue to diversify. Major trends appear to be present in the development of combined techniques, use of new materials, and development of new methodologies. Together, these works constitute a major thrust that could eventually make SPR a common tool for surface interaction analysis and biosensing. The future outlook for SPR and SPR-associated BIA studies, in our opinion, is very bright.      

电化学表面等离子体共振技术

电化学表面等离子体共振(electrochemical surface plasmon resonance,ESPR)技术是近年发展起来的、将表面等离子体共振技术与电化学方法联用的一种新方法。本文在阐明ESPR基本原理及其主要联用方法的基础上,对ESPR技术在金属离子定性/定量分析、纳米薄膜原位动力学研究、电化学聚合反应过程研究、ESPR生物传感等方面的应用进行了详细评述,并提出了提高ESPR检测灵敏度、ESPR与其他技术的联用以及测量装置的微型化、自动化是今后ESPR技术的发展方向。     

金纳米棒——从可控制备与修饰到纳米生物学与生物医学应用

金纳米棒因其独特的光学活性(纵向和横向两个等离子体共振吸收峰,可调范围从可见光区到近红外区)、长径比可调,表面易于修饰,生物相容性良好而使得其在纳米生物学和生物医学等领域具有广泛的应用前景。金纳米棒的合成及表面修饰直接决定着其物理化学性质,进而影响其生物相容性及其在生物医学中的应用。本文综述了金纳米棒的可控制备方法(包括模板法、电化学法、光化学法和晶种法)、表面可控修饰方法及其在纳米生物学和生物医学中的应用新进展,重点总结了金纳米棒的表面可控修饰及其在分子探针、生物传感、生物成像、药物载体、基因载体和光热疗法的最新研究进展。最后针对金纳米棒在生物应用过程中的一些瓶颈问题(如:特异性识别能力需要增强和荧光量子产率尚待提高等)提出了将手性分子或智能聚合物引入到金纳米棒表面进行可控修饰,以期增强其特异性识别能力并提高荧光量子产率,为金纳米棒的发展提供了新的思路。     

表面等离子体共振技术在电化学反应过程研究中的应用

简述了表面等离子体共振(SPR)的基本原理,并综述了表面等离子体共振技术在电化学反应过程中的应用。SPR技术可以无需任何标记原位实时地检测分子间的相互作用,也可用于连续监测吸附/脱附和缔合/解离过程。表面等离子共振光谱(SPRS)与电化学技术结合可用来同时表征和处理电极/溶液的界面,在电化学掺杂/去掺杂过程、吸附/脱附反应的研究、痕量物质的检测、薄膜厚度、介电常数的测定等方面的应用已取得了很大的进展。     

Unveiling the relevance of the redox character of nitroaromatic and nitroheteroaromatic compounds as potential medicines

This review discusses the state of the art, challenges, and perspectives in recent applications of nitroaromatics and nitroheteroaromatics, which are redox-bio-activated drugs or leads, in Medicinal Chemistry. It deals mainly with the electrochemical approach toward the electron transfer-based molecular mechanisms of drug action, drug design, estimation and measurement of redox potentials, correlation of physicochemical and pharmacological data, and electrochemical studies of the main representatives of nitro-containing prodrugs, along with approaches to combat their toxicity issues, aiming at a better therapeutic profile. Electrochemical investigation plays essential roles, being strategic in the design and discovery of potential medicines.     

表面等离子体共振传感技术在高分子研究中的应用

介绍了表面等离子体共振 (SPR)的基本原理和SPR传感器技术的应用现状 ,综述了SPR传感器在高分子科学研究中的应用和发展前景。     

Modeling,docking and dynamics simulations of a non-specific lipid transfer protein from Peganum harmala L.

Non-specific lipid transfer proteins (ns-LTPs), ubiquitously found in various types of plants, have been well-known to transfer amphiphilic lipids and promote the lipid exchange between mitochondria and microbody. In this study, an in silico analysis was proposed to study ns-LTP in Peganum harmala L., which may belong to ns-LTP1 family, aiming at constructing its three-dimensional structure. Moreover, we adopted MEGA to analyze ns-LTPs and other species phylogenetically, which brought out an initial sequence alignment of ns-LTPs. In addition, we used molecular docking and molecular dynamics simulations to further investigate the affinities and stabilities of ns-LTP with several ligands complexes. Taken together, our results about ns-LTPs and their ligand-binding activities can provide a better understanding of the lipid–protein interactions, indicating some future applications of ns-LTP-mediated transport.     

Recent advances in the development of graphene-based surface plasmon resonance (SPR) interfaces

Surface plasmon resonance (SPR) is a powerful technique for measurement of biomolecular interactions in real-time in a label-free environment. One of the most common techniques for plasmon excitation is the Kretschmann configuration, and numerous studies of ligand–analyte interactions have been performed on surfaces functionalized with a variety of biomolecules, for example DNA, RNA, glycans, proteins, and peptides. A significant limitation of SPR is that the substrate must be a thin metal film. Post-coating of the metal thin film with a thin dielectric top layer has been reported to enhance the performance of the SPR sensor, but is highly dependent on the thickness of the upper layer and its dielectric constant. Graphene is a single-atom thin planar sheet of sp2 carbon atoms perfectly arranged in a honeycomb lattice. Graphene and graphene oxide are good supports for biomolecules because of their large surface area and rich π conjugation structure, making them suitable dielectric top layers for SPR sensing. In this paper, we review some of the key issues in the development of graphene-based SPR chips. The actual challenges of using these interfaces for studying biomolecular interactions will be discussed and the first examples of the use of graphene-on-metal SPR interfaces for biological sensing will be presented.     

On-chip bioorthogonal chemistry enables immobilization of in situ modified nanoparticles and small molecules for label-free monitoring of protein binding and reaction kinetics

Efficient methods to immobilize small molecules under continuous-flow microfluidic conditions would greatly improve label-free molecular interaction studies using biosensor technology. At present, small-molecule immobilization chemistries require special conditions and in many cases must be performed outside the detector and microfluidic system where real-time monitoring is not possible. Here, we have developed and optimized a method for on-chip bioorthogonal chemistry that enables rapid, reversible immobilization of small molecules with control over orientation and immobilization density, and apply this technique to surface plasmon resonance (SPR) studies. Immobilized small molecules reverse the orientation of canonical SPR interaction studies, and also enable a variety of new SPR applications including on-chip assembly and interaction studies of multicomponent structures, such as functionalized nanoparticles, and measurement of bioorthogonal reaction rates. We use this approach to demonstrate that on-chip assembled functionalized nanoparticles show a preserved ability to interact with their target protein, and to measure rapid bioorthogonal reaction rates with k(2) > 10(3) M(-1) s(-1). This method offers multiple benefits for microfluidic biological applications, including rapid screening of targeted nanoparticles with vastly decreased nanoparticle synthetic requirements, robust immobilization chemistry in the presence of serum, and a continuous flow technique that mimics biologic contexts better than current methods used to measure bioorthogonal reaction kinetics such as NMR or UV-vis spectroscopy (e.g., stopped flow kinetics). Taken together, this approach constitutes a flexible and powerful technique for evaluating a wide variety of reactions and intermolecular interactions for in vitro or in vivo applications.