Antibodies arrays coated with

The use of sensor arrays should also play an important role in the future. They could be used to simultaneously give an accurate account of many different analytes and an overall result at once. For example, an array of Pz sensors coated with specific antibodies against different freshwater cyanobacterial toxins could be used to give an overall toxicity indication and also a specific result on the concentration and type of each toxin present. Incorporation of miniaturised flow cells and crystals, such as the excellent system developed by Michalzik et al. [152,153], could allow real-time monitoring directly in solution. 

Dai et al. reported a strategy for analyzing proteins by selective binding to antibodies in such a way that nonspecific adsorption and protein de-naturation could be prevented. To this end, poly(acrylic acid)/protonated poly(allylamine) multilayers that are well known to resist nonspecific adsorption of proteins and to allow for covalent immobilization of arrays of active antibodies were coated on the walls of AAO hard templates with... 

Adhesion-based strategies make use of the protein markers expressed by cells in order to immobilize them to specific points within microfluidic devices. This has been identified as a robust and reliable method for POC applications. Typically an antibody with (specific) affinity for the protein marker of interest (e.g., CD4 in HIV diagnostics or EpCAM in CTC testing) is immobilized on the surface of a microfluidic device (Fig. 1). The capture area can be defined in various shapes, patterns, and locations, e.g., to optimize binding and/or detection. This approach was used by Nagrath et al. [3] to isolate CTCs using a microfluidic chip which consisted of an array of 78,000 microposts which were coated with anti-EpCAM antibodies. The posts increased the inner surface area of the chip and thus enhanced the efficiency of CTC capture. Up to 5.1 ml of whole blood, acquired from 116 patients with... 

The wetted fiber types listed in Table 3 have been based on multimode fibers or fiber array bundles. In Fig. 4, the large diameter (1,000 pm) multimode cores are acid etched or stretched to create a sharp probe tip. In either case, the fiber surface is treated for binding proteins or other molecular probes. Walt et al. [7] (Table 3,5th row) developed a chip using a wetted fiber-optic array of thousands of individual fibers in a coherent bundle. By etching the core at the fiber bundle s tip, an array of micro wells was created and loaded with microspheres. The microspheres are coated with various sensing materials such as antibodies. Resulting changes in fluorescence intensity correspond to analyte concentration. 

Figure 16.5 Immunostained peptide arrays after various treatments of fixation, protein cross-linking, and antigen retrieval, as indicated at the top. Each row has a different peptide that is immunoreactive for the antibody denoted to the left. Column A represents the baseline condition, without any treatment whatsoever. Column B shows immunoreactivity of each peptide after overnight formalin fixation. Column C shows the immunoreactivity after first coating the array with an irrelevant protein (casein) followed by overnight formalin fixation. Column D illustrates the immunoreactivity of the peptides after the treatment of column C, and then antigen retrieval. Reproduced with permission from Reference 15, 2006 American Society for Clinical Pathology.

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