Imaging ellipsometry is presented as a technique for quantification and visualization of the lateral thickness distribution of thin ͑0-30 nm͒ transparent layers on solid substrates. The main advantage of imaging ellipsometry is that every point on a surface is measured at the same time with a high lateral resolution. The method is based on the use of combined null and off-null ellipsometry at an incident angle close to the pseudo-Brewster angle of a high index substrate such as silicon. In the present experimental setup, a xenon lamp, a collimator, and a wavelength-selective filter provide an expanded collimated probe beam with a diameter of 25 mm. Other major components in the system are a polarizer, a compensator, and an analyzer. In this way, a 15ϫ30 mm 2 image of a sample surface can be focused onto a charge-coupled-device video camera and transferred to a computer for further evaluation by image processing. Thickness measurements are performed for calibration purposes with ordinary null ellipsometry. The imaging ellipsometer has an accuracy of better than 0.5 nm at a lateral resolution of 5 m in the present configuration, but improvements of at least a factor of 5 can be foreseen. Several aspects of the ellipsometric imaging system are illustrated in selected applications including continuous protein thickness distributions, stepped silicon dioxide thickness distributions, and visualization of protein patterning of surfaces. The latter can be used in a biosensor system as illustrated here by antigen-antibody binding studies.

An immune antibody phage-display library was constructed from B cells of SARS convalescent patients. More than 80 clones were selected from the library by using the whole inactivated SARS-CoV virions as target. One human scFv, B1, was characterized extensively. The B1 recognized SARS pseudovirus in vivo and competed with SARS sera for binding to SARS-CoV with high affinity (equilibrium dissociation constant, K(d) = 105 nM). The B1 also has potent neutralizing activities against infection by pseudovirus expressing SARS-CoV S protein in vitro. Finally, we found that the B1 recognized an epitope on S2 protein, especially within amino acids 1023-1189 of S2 protein. This study not only first made a human neutralizing antibody, which recognized an epitope on S2 protein like natural antibody in sera, but also may help us to better understand the immunological characteristics of SARS protein and SARS vaccine design.

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Surface initiated polymerization (SIP) has become an attractive method for tailoring physical and chemical properties of surfaces for a broad range of applications. Most of those applications relied on the merit of high density coating. In this study, we explored a long overlooked field of SIP: SIP from substrates of low initiator density. We combined ellipsometry with AFM to investigate the effect of initiator density and polymerization time on the morphology of polymer coatings. In addition, we carefully adjusted the nanoscale separation of polymer chains to achieve a balance between nonfouling and immobilization capacities. We further tested the performance of those coatings on various biosensors, such as quartz crystal microbalance, surface plasmon resonance, and protein microarrays. The optimized matrices enhanced the performance of those biosensors. This report shall encourage researchers to explore new frontiers in SIP that go beyond polymer brushes.KEYWORDS: surface initiated polymerization • biosensor matrix • quartz crystal microbalance • surface plasmon resonance • protein microarray S urface initiated polymerization (SIP) was initially designed to overcome the concentration barrier problem commonly suffered in the "grafting to" strategy, so that higher grafting density (>0.06 chain nm -2 ) (1) could be achieved. As a "grafting from" strategy, SIP grew polymers from the surface tethered initiators, which could be immobilized to surfaces with high density via well-established techniques such as that of self-assembled monolayer (SAM) (2, 3). SIP has been used to tailor physical and chemical properties of surfaces for a broad range of substrates and applications. Substrates include inorganic (4-9), polymer (10-13), metal (14-17), semiconductor (18), ceramic (19), and biological materials (20)(21)(22). Applications include nonfouling (23-27), wettability (28-31), responsive surfaces (32-35), corrorison resistance (36), lithographic coating (37), colloid stability (5), and stealth effect (22, 38). Most of those applications relied on the merit of higher density coating achieved by SIP. However, we found that only SIP from a low, not high, initiator density could produce superhydrophobic surfaces (39). This finding reminded us that SIP not only produced high density brushes but also allowed us to precisely control many aspects of the resulting polymers, such as film thickness and density, composition (i.e., block copolymers), and functionality. Inspired by this finding, we decided to explore a long overlooked field of SIP: SIP from substrates of low initiator density. Specificially, we applied SIP from substrates of low initiator density to prepare biosensor matrices.The design and preparation of biosensor matrices have attracted a great deal of interest because the performance of biosensors is greatly affected by the characteristics of matrices, such as their chemical composition, three-dimensional (3D) structures, mechanical properties, and biocompatibility. For example, Liedberg et al. developed...