An enzyme-amplified diffraction-based immunoassay

Development of a Qualitative Sequential Immunoassay for Characterizing the Intrinsic Properties of Circulating Cardiac Troponin I

“…8I-7 as the capture antibody recognizing epitope in the constant region allowed us to elucidate the degraded forms of cTnI, although it is possible that there are uncharacterized circulating forms of cTnI not captured by 8I-7. Third, amplifying detection of the analyte, by use of an HRP-linked detector antibody and a precipitating form of TMB substrate (22 ), is a unique feature of the dotLab System that expands the dynamic range of the assay and increases the sensitivity of the real-time assay to the ng/L-g/L (23 ) range; it was previously limited to traditional end-point ELISA (28,29 ). Use of precipitable TMB is possible because the instrument allows flow rate to be modified, even to 0, on the basis of experimental needs, and the internal size of the flow tubing is wide enough for the precipitates to pass through.…”

“…The subsequent capture of the analyte (purified analyte or serum) alone or bound to a detector antibody increases the average height of the surface pattern and causes an increase in the diffraction intensity (DI) signal that is recorded in real time. The DI signal is directly related to the size and quantity of the bound complex (22,23 ).…”

“…The protocol uses diffractive optics technology, bringing together the techniques of grating-based light diffraction and immobilized capture surfaces to allow sequential analysis of the captured antigen (22,23 ). This method can directly measure circulating cTnI to determine if it is phosphorylated or degraded at either the N-or C-terminus.…”

Surface-relief-gratings based on molecularly imprinted polymer for 2,4-dichlorophenoxyacetic acid detection

“…Recently, optical sensors based on diffraction gratings have been developed as a new sensing platform [1][2][3][4][5][6][7][8][9][10][11][12][13]. In this sensing protocol, sensitive substrates or materials are patterned into period arrays by soft lithography or other methods.…”

“…Compared with sensors transducing the recognitions through electricity, acoustics and other optical methods, which have been widely studied for scientific explorations and applications, this kind of grating-based sensor is simple, inexpensive and high efficiency. Owing to these advantages, diffraction grating sensors have been applied for chemical and biological detection and diagnosis of various substances, such as volatile compound [1], DNA [2], protein [7], antigen and antibody [5,6,8,10], and glucose [11,12]. More generally speaking, the diffraction grating sensors can be considered as a new branch of sensing based on diffraction effects [14,15].…”