A fluorescent molecularly imprinted device for the on-line analysis of AFP in human serum

Dual-mode electrochemiluminescence and electrochemical sensor for alpha-fetoprotein detection in human serum based on vertically ordered mesoporous silica films

In this study, we demonstrated the highly sensitive detection of alpha-fetoprotein (AFP) by electrochemiluminescence (ECL) and electrochemistry (EC) based on the gated transport of the bifunctional probe (tris(1,10-phenanthroline) ruthenium (II) chloride, Ru (phen)₃Cl₂) into the nanochannels of vertically ordered mesoporous silica films (VMSFs). Due to the negatively charged surface and ultrasmall pore size, VMSF displays a signal amplification effect on Ru (phen)₃Cl₂ and is suitable for the construction of sensors with excellent sensitivity. With the linkage of (3-glycidyloxypropyl) trimethoxysilane, the anti-AFP antibody could covalently bind to the external surface of VMSF, generating a highly specific recognized sensing interface toward AFP. When AFP is presented, the formed immunocomplex hinders the diffusion of Ru (phen)₃Cl₂ to the underlying electrode surface, resulting in a decreased ECL or EC response. The dual-mode detection of AFP is achieved with a relatively low limit of detection (0.56 fg/ml for ECL and 4.5 pg/ml for EC) and a wide linear range (10 fg/ml∼1 μg/ml for ECL and 10 pg/ml∼1 μg/ml for EC). Moreover, owing to the inherent anti-fouling property of VMSF, satisfactory results in the analysis of human serum were obtained, showing the great potential of the designed strategy in clinical diagnosis.

In situ growth of WO3/BiVO4 nanoflowers onto cellulose fibers to construct photoelectrochemical/colorimetric lab-on-paper devices for the ultrasensitive detection of AFP

In this work, novel dual-mode lab-on-paper devices based on in situ grown WO₃/BiVO₄ heterojunctions onto cellulose fibers, as signal amplification probes, were successfully fabricated by the integration of photoelectrochemical (PEC)/colorimetric analysis technologies into a paper sensing platform for the ultrasensitive detection of alpha-fetoprotein (AFP). Specifically, to achieve an impressive PEC performance of the lab-on-paper device, the WO₃/BiVO₄ heterojunction was in situ grown onto the surface of cellulose fibers assisted with Au nanoparticle (Au NP) functionalization for enhancing the conductivity of the working zone of the device. With the target concentration increased, more immune conjugates could be captured by the proposed paper photoelectrode, which could lead to a quantitative decrease in the photocurrent intensity, eventually realizing the accurate PEC signal readout. To meet the requirement of end-user application, a colorimetric signal readout system was designed for the lab-on-paper device based on the color reaction of 3,3'5,5'-tetramethylbenzidine (TMB) oxidized by WO₃/BiVO₄ nanoflowers in the presence of H₂O₂. Noticeably, it is the first time that the WO₃/BiVO₄ heterojunction is in situ grown onto cellulose fibers, which enhances the sensitivity in view of both their PEC activity and catalytic ability. By controlling the conversion process of hydrophobicity and hydrophilicity on the lab-on-paper device combined with diverse origami methods, the dual-mode PEC/colorimetric signal output for the ultrasensitive AFP detection was realized. Under optimal conditions, the proposed dual-mode lab-on-paper device could enable the sensitive PEC/colorimetric diagnosis of AFP in the linear range of 0.09-100 ng mL^-1 and 5-100 ng mL^-1 with the limit of detection of 0.03 and 1.47 ng mL^-1, respectively.

Colorimetric detection of human alpha-2-macroglobulin by janus imprinted nanoparticles constructed dual molecular imprinting immunosandwich strategy

Simple and rapid detection of disease-related bio-markers are significant for early clinical diagnosis and can potentially improve the survival rate. However, establishing a high-specificity colorimetric detection method for bio-markers are still challenges due to their inevitable natural antibody used or enzymatic labeling. Herein, a cost-efficient and easy-to-use approach, which called dual molecular imprinting immunosandwich colorimetric strategy (DMI-ICS) was constructed for detection alpha-2-macroglobulin (α2MG) by janus imprinted nanoparticles. The unique detection principle was contained with two mimic antibody parts, the first part was α2MG glass slides molecularly imprinted material (GS-MIP) as a "Separation antibody", which can specifically rapid separate the protein in the complex sample; Another part was asymmetrically modified janus molecularly imprinted gold nanoparticles nanozyme (J-GNPs-MIP) as a "Detection antibody", which has the properties of specific recognition and catalytic substrate color performance at the same time. The concentration of α2MG can be determined by the substrate color changes and observed with naked eyes. Under the optimized conditions, the DMI-ICS had a great performance and offering lower relative standard deviation (RSD, 7.69%), good linear range (0.297-130 μg/mL, R² = 0.994), high imprinting factor (IF: 3.74) with lower detection limit (0.089 μg/mL). This strategy provides an easy operation and low cost signal readout method for direct detection and separation of α2MG in human serum samples, which is a versatile tool for point-of-care diagnosis, while also offering a new perspective on antibody simulation technology, multifunctional antibody preparation and contribute to detection of disease-related bio-marker in nonspecialized laboratory infrastructure.