High spatial resolution label-free detection of antigen–antibody binding on patterned surface by imaging ellipsometry

An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers

The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(ω-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R_q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified.

Micropattern of antibodies imaged by shear force microscopy: comparison between classical and jumping modes

Quartz tuning fork devices are increasingly being used as nanosensors in Scanning Probe Microscopy. They offer some benefits with respect to standard microfabricated cantilevers in certain experimental setups including the study of biomolecules under physiological conditions. In this work, we compare three different working modes for imaging micropatterned antibodies with quartz tuning fork sensors: apart from the classical amplitude and frequency modulation strategies, for first time the jumping mode is implemented using tuning forks. Our results show that the molecules suffer less degradation when working in the jumping mode, due to the reduction of the interaction forces.

Planar protein arrays in microtiter plates: development of a new format towards accurate, automation-friendly and affordable (A(3)) diagnostics

A technology for protein microarrays in 96 well microplates has been developed as a widely adoptable platform for multiplexed protein based diagnostics. Procedures for protein microarray manufacturing, immobilization, assay optimization and optical detection methods were developed. Using a clever combination of state of the art technologies, a versatile platform that works with peptides, proteins and antibodies as capture agents in a scalable format for planar arrays is described.