Oligolayer-coated nanoparticles: impact of surface topography at the nanobio interface.

Layer-by-layer coating of nanoparticles with a layer number in the single-digit range has gained increasing attention in the field of nanomedicinal research. However, the impact of using various polyelectrolytes on oligolayer formation and, more importantly, their influence on the interaction with the biological system has not often been considered in the past. Hence, we investigated the polyelectrolyte deposition profiles and resulting surface topographies of up to three polyelectrolyte layers on a flat gold sensor surface using three different polycations, namely, poly(ethylene imine) (PEI), poly(allylamine hydrochloride) (PAH), and poly(diallylammonium chloride) (PD), each in combination with poly(styrenesulfonate) (PSS).

Label-free monitoring of cell-based assays: combining impedance analysis with SPR for multiparametric cell profiling.

Label-free approaches to monitor cell-based assays provide an unprecedented, time-resolved and non-invasive view on the response of mammalian cells to chemical, biological or physical stimuli. The most widespread techniques are impedance analysis and optical sensing using evanescent waves like SPR. This study describes the combination of both in one experimental setup so that a given cell population can be monitored simultaneously for electrical and optical changes.

Real-time label-free monitoring of the cellular response to osmotic stress using conventional and long-range surface plasmons.

Cell volume and its regulation are key factors for cellular integrity and also serve as indicators of various cell pathologies. SPR sensors represent an efficient tool for real-time and label-free observations of changes in cell volume and shape. Here, we extend this concept by employing the use of long-range surface plasmons (LRSP).

Studying cell-surface interactions in vitro: a survey of experimental approaches and techniques.

A better understanding of the interactions of animal (or human) cells with in vitro surfaces is the key to the successful development, improvement and optimization of biomaterials for biomedical or biotechnological purposes. State-of-the-art experimental approaches and techniques are a prerequisite for further and deeper insights into the mechanisms and processes involved in cell-surface adhesion. This chapter provides a brief but not complete survey of optical, mechanical, electrochemical and acoustic devices that are currently used to study the structural and functional properties of the cell-surface junction.

Label-free and time-resolved measurements of cell volume changes by surface plasmon resonance (SPR) spectroscopy.

Cell volume and its regulation is one of the key players for cellular integrity and a strong indicator for several cell pathologies. But time-resolved volume measurements of adherently grown mammalian cells using established methods, such as extracellular impedance analysis or light microscopy, are complex and time-consuming. In this study, we demonstrate that surface plasmon resonance spectroscopy (SPR) is a powerful transducer device capable of reporting volume changes of cells that are directly grown on the SPR sensor surface.

Imaging of G protein-coupled receptors in solid-supported planar lipid membranes.

This contribution summarizes first some of our efforts in imaging G-protein-coupled receptor (GPCR) functional inserted into planar tethered lipid bilayer membranes (tBLMs) as a novel platform for biophysical studies. The authors introduced recently a novel approach for the functional incorporation of membrane proteins, i.e.

Surface plasmon resonance spectroscopy and quartz crystal microbalance study of streptavidin film structure effects on biotinylated DNA assembly and target DNA hybridization.

Surface plasmon resonance (SPR) spectroscopy is employed for the study of biotinylated DNA assembly on streptavidin modified gold surfaces for target DNA hybridization. Two immobilization strategies are involved for constructing streptavidin films, namely, (1) physical adsorption on biotin-containing thiol treated surfaces through biotin-streptavidin links and (2) covalent attachment to 11-mercaptoundecanoic acid (MUA) treated surfaces through amine coupling. To understand the structural properties of the streptavidin films, a quartz crystal microbalance with energy dissipation monitoring (QCM-D) is used to monitor the streptavidin immobilization procedures.

Surface plasmon resonance spectroscopy and quartz crystal microbalance study of MutS binding with single thymine-guanine mismatched DNA.

MutS is a DNA mismatch binding protein that recognizes heteroduplex DNA containing mispaired or unpaired bases. In this study, we employ a quartz crystal microbalance (QCM) and a surface plasmon resonance (SPR) device for the study of MutS binding with DNA containing a single Thymine-Guanine (T-G) mismatch at different sites. Multi-step surface binding reactions are involved in the study, including probe DNA immobilization on the sensor surface through biotin-streptavidin-biotin bridge chemistry, target DNA hybridization to form T-G heteroduplexes, and MutS recognition of the mutation sites.

Multiplexed hybridization detection of quantum dot-conjugated DNA sequences using surface plasmon enhanced fluorescence microscopy and spectrometry.

In this study, the general suitability of quantum dot (QD)-DNA conjugates for the surface plasmon enhanced fluorescence spectroscopy technique is demonstrated. Furthermore, the QD-DNA system is transferred to the platform of surface plasmon enhanced fluorescence microscopy. Using this technique together with a microarray format, in which the sensor-bound single-stranded catcher probes are organized in individual surface spots, results in a simultaneous qualitative analysis of QD-conjugated analyte DNA strands as multicolor images.

Crystal structures of the antitermination factor NusB from Thermotoga maritima and implications for RNA binding.

NusB is a prokaryotic transcription factor involved in antitermination processes, during which it interacts with the boxA portion of the mRNA nut site. Previous studies have shown that NusB exhibits an all-helical fold, and that the protein from Escherichia coli forms monomers, while Mycobacterium tuberculosis NusB is a dimer. The functional significance of NusB dimerization is unknown.

Detection of point mutation and insertion mutations in DNA using a quartz crystal microbalance and MutS, a mismatch binding protein.

MutS protein is a mismatch binding protein that recognizes mispaired and unpaired base(s) in DNA. In this study, we incorporate the MutS protein-based mutation recognition into quartz crystal microbalance (QCM) measurements for DNA single-base substitution mutation and 1-4 base(s) insertion (or deletion) mutation detection. The method involves the immobilization of single-stranded probe DNA on a QCM surface, the hybridization of target DNA to form homoduplex or heteroduplex DNA, and finally the application of MutS protein for the mutation recognition.

RNA DNA discrimination by the antitermination protein NusB.

The regulation of ribosomal RNA biosynthesis in Escherichia coli by antitermination requires binding of NusB protein to a dodecamer sequence designated boxA on the nascent RNA. The affinity of NusB protein for boxA RNA exceeds that for the homologous DNA segment by more than three orders of magnitude as shown by surface plasmon resonance measurements. DNA RNA discrimination by NusB protein was shown to involve methyl groups (i.

Transcriptional regulation by antitermination. Interaction of RNA with NusB protein and NusB/NusE protein complex of Escherichia coli.

A recombinant heterodimeric NusB/NusE protein complex of Escherichia coli was expressed under the control of a synthetic mini operon. Surface plasmon resonance measurements showed that the heterodimer complex has substantially higher affinity for the boxA RNA sequence motif of the ribosomal RNA (rrn) operons of E.coli as compared to monomeric NusB protein.