Binding behavior of CRP and anti-CRP antibody analyzed with SPR and AFM measurement

Kinetic analysis of antibody binding to integral membrane proteins stabilized in SMALPs

The fundamental importance of membrane protein (MP) targets in central biological and cellular events has driven a marked increase in the use of membrane mimetics for exploring these proteins as therapeutic targets. The main challenge associated with biophysical analysis of membrane protein is the need for detergent extraction from the bilayer environment, which in many cases causes the proteins to become insoluble, unstable or display altered structure or activity. Recent technological advances have tried to limit the exposure of purified membrane protein to detergents. One such method involves the amphipathic co-polymer of styrene and maleic acid (SMA), which can release lipids and integral membrane proteins into water soluble native particles (or vesicles) termed SMALPs (Styrene Maleic Acid Lipid Particles). In this study, assay conditions that leverage SMA for membrane protein stabilization were developed to perform kinetic analysis of antibody binding to integral membrane protein and complexes in SMALPs in both purified and complex mixture settings using multiple biosensor platforms. To develop a robust and flexible platform using SMALPs technology, we optimized various SPR assay formats to analyze SMALPs produced with cell membrane pellets as well as whole cell lysates from the cell lines overexpressing membrane protein of interest. Here we emphasize the extraction of model membrane proteins of diverse architecture and function from native environments to encapsulate with SMALPs. Given the importance of selected membrane targets in central biological events and therapeutic relevance, MP-specific or tag-specific antibodies were used as a proof-of-principal to validate the SMALPs platform for ligand binding studies to support drug discovery or tool generation processes. MP-SMALPs that retain specific binding capability in multiple assay formats and biosensors, such as waveguide interferometry and surface plasmon resonance, would be a versatile platform for a wide range of downstream applications.

Application of paper-supported printed gold electrodes for impedimetric immunosensor development

In this article, we report on the formation and mode-of-operation of an affinity biosensor, where alternate layers of biotin/streptavidin/biotinylated-CRP-antigen/anti-CRP antibody are grown on printed gold electrodes on disposable paper-substrates. We have successfully demonstrated and detected the formation of consecutive layers of supra-molecular protein assembly using an electrical (impedimetric) technique. The formation process is also supplemented and verified using conventional surface plasmon resonance (SPR) measurements and surface sensitive characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The article provides a possible biosensor development scheme, where-(1) fabrication of paper substrate (2) synthesis of gold nanoparticle inks (3) inkjet printing of gold electrodes on paper (4) formation of the biorecognition layers on the gold electrodes and (5) electrical (impedimetric) analysis of growth-all are coupled together to form a test-structure for a recyclable and inexpensive point-of-care diagnostic platform.

MOSFET-BJT hybrid mode of the gated lateral bipolar junction transistor for C-reactive protein detection

In this study, we propose a novel biosensor based on a gated lateral bipolar junction transistor (BJT) for biomaterial detection. The gated lateral BJT can function as both a BJT and a metal-oxide-semiconductor field-effect transistor (MOSFET) with both the emitter and source, and the collector and drain, coupled. C-reactive protein (CRP), which is an important disease marker in clinical examinations, can be detected using the proposed device. In the MOSFET-BJT hybrid mode, the sensitivity, selectivity, and reproducibility of the gated lateral BJT for biosensors were evaluated in this study. According to the results, in the MOSFET-BJT hybrid mode, the gated lateral BJT shows good selectivity and reproducibility. Changes in the emitter (source) current of the device for CRP antigen detection were approximately 0.65, 0.72, and 0.80 μA/decade at base currents of -50, -30, and -10 μA, respectively. The proposed device has significant application in the detection of certain biomaterials that require a dilution process using a common biosensor, such as a MOSFET-based biosensor.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.