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Surface plasmon resonance (SPR) detectors monitor molecular interactions without labels and in real time. SPR imaging (SPRi) has the additional advantage of increased throughput since it monitors binding to arrays of molecules. Indeed, the coupling of quantitative, label-free, mass-sensitive SPR technology with array capabilities has been used successfully in many diverse applications such as characterizing antibody–antigen interactions, proteins binding to aptamers, transcription factors binding to DNAs, and profiling cell surface receptors on ligand arrays. 

This tutorial describes a novel SPRi-based assay for measuring drug absorption to natural membrane arrays. This general protocol can be used in drug evaluation since it can investigate absorption of a drug to cell membranes from multiple tissue sources arrayed on a single chip.

Current Methodology

The bioavailability of a drug is influenced by its ability to cross cell membranes, so a drug’s absorption profile is a crucial factor affecting drug efficacy. A number of approaches to evaluate drug absorption and lipid permeability are in use including tissue diffusion assays, cell-based permeability assays, noncell-based assays such as liposome chromatography and parallel artificial membrane permeability assays. These applications, however, are not readily amenable to multiplexing; rely on downstream analytical procedures such as UV spectroscopy or mass spectrometry; and often require synthesis of radio- or fluorescently labeled marker compounds.