Luminescent Labels—More than Just an Alternative to Radioisotopes?

Abstract

Chemical, chromatographic, or spectrometric methods are generally unsuitable for the detection of molecules in the nano and subnanogram region because of their low sensitivity. The radioimmunoassay (RIA) developed by Yalow and Berson in 1959 combined the high sensitivity of radioactively labeled substances with the high specificity of immunological reactions for the first time. In this way it was possible to detect quantitatively the tiniest traces of substances in the presence of an excess of other, in some cases, similar foreign substances without prior enrichment. Immunoassays have certainly developed to become the most valuable analytical tool of in vitro diagnostics and are today routinely employed for the detection of endogenous and exogenous substances (e.g. hormones, tumor‐associated proteins, bacteria, viruses, toxins, drugs, etc). The many disadvantages of radioactivity such as the required handling licenses, disposal costs, precautions necessary to prevent risks to health, short shelf‐life, and limited sensitivity soon led to the search for other nonradioactive labeling methods. Encouraged by the development of light measuring techniques and the commercial availability of highly sensitive apparatus, radioactive isotopes as labels are today being replaced increasingly by enzymes, fluorophores, or luminophores. Some of the new luminescent labels have, however, not only facilitated replacement of radioisotopes, but also a breakthrough into what has until now been unattainable levels of sensitivity. The following article reviews the methods of luminescent labeling and their applications mainly in the area of immunoassays.

Multiple scanning electrochemical microscopy mapping of tyrosinase in micro-contact printed fruit samples on polyvinylidene fluoride membrane

“…Indeed, proteins are usually visualized by optical techniques based on protein staining such as silver staining [31], fluorescent dyes [15] or organic substances [32]. Although those traditional methods are powerful, they are time consuming and require the use of expensive dyes.…”

“…Among the different employed membranes for protein blotting and detection, polyvinylidene fluoride (PVDF) is widely used since it is a highly hydrophobic and porous support with a superior protein binding capacity and a remarkable mechanical and chemical stability. Moreover, PVDF maintains the enzymatic activity of adsorbed proteins and is compatible with different protein labeling protocols including the ones based on Coomassie Blue, silver or gold staining and fluorescent or chemiluminescent dyes [10][11][12][13][14][15][16]. Recently, proteins immobilized on PVDF membranes have also been detected and employed for the visualization of human finger prints by scanning electrochemical microscopy (SECM) [17].…”

Lewis acid free high speed synthesis of nimesulide-based novel N-substituted cyclic imides

“…[1][2][3][4][5][6][7][8][9][10][11] On the other hand N-(4-nitro-2-phenoxy phenyl) methanesulfonamide or nimesulide B (see Figure 1), a preferential cyclooxygenase-2 (COX-2) inhibitor is one of the well known non-steroidal anti-inflammatory drugs (NSAIDs) that has been utilized to treat pain and other inflammatory diseases. Because of their common antiinflammatory properties and our interest in nimesulide derivatives 12 as potential anti-inflammatory agents we decided to prepare compound C having structural features of both A and B.…”

N-(4-Methylsulfonamido-3-phenoxyphenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximide

“…Cyclic imides A (Scheme 1) represent an important class of bioactive molecules that shows a wide range of pharmacological activities such as androgen receptor antagonistic, anti-inflammatory, anxiolytic, antiviral, antibacterial, antitumor, antispasmodic, antinociceptive and antineoplastic properties [1][2][3][4][5][6][7][8][9][10][11][12][13].…”