Antifouling Aptasensor Based on Self-Assembled Loop-Closed Peptides with Enhanced Stability for CA125 Assay in Complex Biofluids

As a class of oligosaccharide chain-containing proteins, glycoproteins are of great value in screening and early diagnosis of malignant tumors and other major diseases. Herein, we report a universal boronate affinity-based electrochemical aptasensor for point-of-care glycoprotein detection. Aptasensing of glycoproteins involves the specific recognition and capture of target glycoproteins by end-tethered nucleic acid aptamers and the site-specific labeling of ferrocene tags via the phenylboronic acid (PBA)-based boronate affinity interactions because the cis-diol sites of oligosaccharide chains on glycoproteins can selectively react with the PBA receptor groups to form cyclic phenylborates in aqueous basic media. Due to the presence of hundreds to thousands of cis-diol sites on a glycoprotein, a large number of ferrocene tags can be recruited for the signal-on aptasensing of glycoproteins at a low-abundance level, eliminating the need for extra amplification strategies. As a result, the boronate affinity-based electrochemical aptasensor is highly sensitive and selective for glycoprotein detection and tolerant to the false-positive results. The detection limit for α-fetoprotein (AFP) is 0.037 ng/mL, with a linear response ranging from 0.1 to 100 ng/mL. In addition to the merits of simple operation, short assay time, and low detection cost, the aptasensor is applicable to the detection of glycoproteins in serum samples and the point-of-care detection using disposable flexible electrodes. Overall, this work provides a universal and promising platform for the point-of-care detection of glycoproteins, holding great potential in screening and early diagnosis of glycoprotein-related malignant tumors and other major diseases.

mentioning

confidence: 99%

Boronate Affinity-Based Electrochemical Aptasensor for Point-of-Care Glycoprotein Detection

et al. 2022

“…Using antibodies as the specific bioaffinity elements, various immunoassays have been established for the detection of glycoprotein tumor biomarkers, such as electrochemical, − photoelectrochemical, − chemiluminescent, , colorimetric, , surface-enhanced Raman scattering, − fluorescent, , and electrochemiluminescent immunosensors. − These immunoassays are highly selective; however, the use of antibodies as the bioaffinity elements suffers from the drawbacks of poor stability and high assay cost. With this in mind, great effort has nowadays been focused on the aptasensing of glycoprotein tumor biomarkers, − in view of the high stability, low production cost, minimal interbatch variability, and high specificity of aptamers. − For example, a wide variety of electrochemical aptasensors have been constructed for the highly sensitive and selective detection of tumor biomarkers, − on the basis of the signal amplification by catalytic reactions (using enzymes or nanoparticle electrocatalysts) and nanoparticle carriers. Nevertheless, these amplification strategies intrinsically suffer from the disadvantages of high cost, poor stability, and the need for tedious and sophisticated operation …”

mentioning

confidence: 99%

Electrochemically Controlled Atom Transfer Radical Polymerization for Electrochemical Aptasensing of Tumor Biomarkers

Cao

et al. 2022

Tumor biomarkers are of great value in the liquid biopsy of malignant tumors. In this work, a simple and cost-friendly electrochemical aptasensor was presented for the highly sensitive and selective detection of glycoprotein tumor biomarkers. The DNA aptamer-modified electrode was used as the sensing interface to specifically capture the target glycoprotein tumor biomarkers, to which the alkyl halide initiators for atom transfer radical polymerization (ATRP) were then attached via the esterification crosslinking between the boronic acid group and the cis-dihydroxyl sites of the conjugated oligosaccharide chains on glycoprotein tumor biomarkers followed by the growth of long-chain polymers through electrochemically controlled ATRP (eATRP) to efficiently recruit the ferrocene detection tags. As there are tens to hundreds of cis-dihydroxyl sites on a glycoprotein tumor biomarker for attaching ATRP initiators while each long-chain polymer can recruit hundreds to thousands of ferrocene detection tags, a significantly high current signal can be generated even in the presence of ultralow-abundance targets. Hence, the eATRP-based electrochemical aptasensor is capable of sensitively and selectively detecting glycoprotein tumor biomarkers. Using alpha-fetoprotein as the model target, the limit of detection was demonstrated to be 0.32 pg/mL. Moreover, the aptasensor has been successfully applied to detect glycoprotein tumor biomarkers in human serum samples. In view of its high sensitivity and selectivity, simple operation, and cost-friendliness, the eATRP-based electrochemical aptasensor shows great promise in the glycoprotein-based liquid biopsy of malignant tumors, even at the early stage of development.

“…More importantly, not only is a linear range between the maximum ECL intensity (the mean value for three parallel measurements) and the logarithm of the CA125 concentration from 0.5 mU/mL to 1 U/mL ( R 2 = 0.99) achieved, but also the limit of detection (LOD) is obtained at 0.1 mU/mL with a signal-to-noise ratio (S/N) of 3 (inset of Figure B). The performance of the MUA-AuNCs-based ECL immunosensor is superior to the previously reported CA125 immunosensors. − …”

Section: Resultsmentioning

confidence: 81%

Surface Defect-Involved and Single-Color Electrochemiluminescence of Gold Nanoclusters for Immunoassay

Gao

Wang

et al. 2022

Single-color electrochemiluminescence (ECL) of nanoparticles is normally achieved in a bandgap engineered route via passivating the nanoparticle surface. Herein, when linear mercaptoalkanoic acids are employed as the thiolcapping agent of unary Au nanoclusters (NCs), a single-stabilizer-capped strategy is proposed to achieve surface defect-involved and single-color ECL from the AuNCs with hydrazine (N 2 H 4 ) as the coreactant. The carbon skeleton of the linear mercaptoalkanoic acids exhibits important effects on the ECL of the AuNCs, and efficient oxidative−reductive ECL is achieved with 8-mercaptooctanoic acid (MOA), 11-mercaptoundecanoic acid (MUA), and 12-mercaptododecanoic acid (MDA) capped AuNCs, respectively. The ECL of these AuNCs not only exhibits similar ECL intensity−potential profiles with the same maximum emission potential of ∼1.20 V (vs Ag/AgCl), but also demonstrates almost identical spectral ECL profiles of the same maximum emission wavelength around 713 nm as well as the same fwhm of 64 nm. The ECL of AuNCs/N 2 H 4 is obviously red-shifted to the photoluminescence of AuNCs, which not only provides unambiguous evidence that bandgap-engineered ECL of these AuNCs is quenched but also manifests that the capping agent of linear mercaptoalkanoic acid is promising for the achievement of surface defect-involved and single-color ECL from AuNCs. The MUA capped AuNCs can be utilized as an ECL tag for a sensitive and selective immunoassay, which exhibits a broad linear range from 0.5 mU/mL to 1 U/mL with a low limit of detection of 0.1 mU/mL (S/N = 3) with CA125 as the model analyte. This work provides a promising alternative to the traditional surface-passivating strategy for the achievement of single-color ECL from nanoparticle luminophores.