A label‐free and signal‐amplifiable assay method for colorimetric detection of carcinoembryonic antigen

Abstract

In this work, an innovative colorimetric assay method for the determination of carcinoembryonic antigen is developed with aptamer probes utilized as recognition element. DNA hybridization chain reaction is used as signal amplification technique, and peroxidase-mimicking hemin/G-quadruplex-assisted catalytic oxidation of 2,2'azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) is deployed as signal reporting mechanism. The detection principle was firstly verified by using gel electrophoresis analysis and absorbance measurements. After condition optimization, a detection limit was theoretically determined as 24.8 ng/ml. Furthermore, the method exhibited good selectivity and satisfactory recovery rates (92.2%-108.6%) in serum samples. Moreover, the sensing scheme is easily extended for the detection of other analytes via similar target-aptamer recognition principle. To sum up, this is an enzyme-and label-free, cost-effective yet signal-amplifiable assay scheme for the determination of tumor markers with promising simplicity and selectivity, practical utility, and potential universality.

Recent Advances in Nanomaterial‐based Optical Biosensors as Potential Point‐of‐Care Testing (PoCT) Probes in Carcinoembryonic Antigen Detection

“…The colourless TMB is converted into blue colour after it is oxidized by the hydroxyl radicals generated from the peroxidase catalytic reaction [77,80a, 82] . Besides, the 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) and 4‐aminoantipyrine are typical colour developing reagents that are also responsive to hydroxyl radicals but result in green and red coloured solutions respectively [78d,80c] . Otherwise, there is a collection of studies that take the advantage of nanoscale noble metals such as special optical properties due to quantum effect [83] or plasmonic effect [78c] .…”

“…The selectivity of the sensing probe can be achieved by having the antigen‐antibody immunoassay [73a,77–78,80a–c,82a,83–86] or aptamer‐labelled biosensor [78d,79,80d,81] . Nevertheless, the labelled free system [78d,85] is suggested to overcome the shortcoming of labelled one as aptasensor that utilises the single‐stranded oligonucleotides chain as biorecognition site with an improved affinity towards analyte. The modifications of both the labelled and non‐labelled sensing probes are illustrated as follows.…”

“…The more blocker gets detached from the HRC complexes as the more CEA is added into the system. Thus, the higher the amplification of the signal corresponds to the more intense absorbance peak [78d] …”

Bio-inspired aptamers decorated gold nanoparticles enable visualized detection of malathion

“…To circumvent the potential problems mentioned above, aptamer can provide an ideal solution. Aptamer is single-strand oligonucleotide probe achieved by in vitro selection process called systematic evolution of ligands by exponential enrichment (SELEX) (Meng et al, 2015), which targets to a wide range of analytes, such as small molecules (Lou et al, 2019;Luo et al, 2019), metal ions (Raducanu et al, 2020), proteins (Lo et al, 2021), tumor markers (Li et al, 2022), and even the whole cells (Lv et al, 2021). Aptamer possesses many advantages, such as ease of synthesis and modification, small size, high affinity, low cost, high thermal stability, wide types of targets, and compatible for many signal reporting techniques.…”