Morphologically Flex Sm-MOF Based Electrochemical Immunosensor for Ultrasensitive Detection of a Colon Cancer Biomarker

Abstract

Despite having the potential to synthesize stable metal−organic frameworks (MOFs), rare earth metal-based MOFs have not been exploited extensively. Owing to the high coordination numbers, the MOFs can generate a suitable coordination environment for various applications. Herein, samarium (Sm)-based MOFs were synthesized with three different organic linkers, namely, trimesic acid (TMA), meso-tetra(4carboxyphenyl)porphine (TCPP), and 1,3,6,8-tetra(4-carboxylphenyl) pyrene(TBPy) by the solvothermal approach. The morphologies of Sm-TMA MOF, Sm-TCPP MOF, Sm-TBPy MOF were rod-shaped, cubic consisting of stacked 2D layers, and spherical made of small cubic structures, respectively. After the electrochemical properties of the synthesized MOFs were investigated, the MOFs were used to fabricate immunosensors for detection of carcinoembryonic antigen using a label-free signaling strategy. The immunosensors exhibited a wide linear detection range and a lower detection limit. The exhibited reproducibility and selectivity of the immunosensors were within the tolerable limits. The established label-free immunosensor has been successfully applied for detection of carcinoembryonic antigen in human serum samples, demonstrating that the rare earth metal-based MOFs are promising for construction of biosensors for medical diagnosis.

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

“…To date, numerous methods have been proposed for glycoprotein detection. , Relative to dynamic light scattering (DLS), fluorescence, , surface-enhanced Raman scattering (SERS), colorimetry, mass spectrometry (MS), surface plasmon resonance (SPR), electrochemiluminescence (ECL), − and photoelectrochemistry (PEC), − electrochemical biosensors have received much more attention due to their simplicity, cost-effectiveness, portability, and high sensitivity and selectivity. − For the specific capture of target glycoproteins, molecularly imprinted polymers (MIPs), antibodies, , and nucleic acid aptamers − are typically used as recognition elements. Among them, nucleic acid aptamers have attracted great interest because they can be chemically synthesized and hold the merits of easy modification, high selectivity and affinity, low cost, and high stability. , For example, Zhao et al reported an electrochemical aptasensor for the signal-on detection of carbohydrate antigen 15-3 (CA15-3) and vascular endothelial growth factor 165 (VEGF 165 ), and the detection limit was 66 ng/mL for CA15-3.…”

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

“…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.…”

Novel electrochemical PMI marker biosensor based on quantum dot dissolution using a double-label strategy

“…However, we did not try to optimize the pH and incubation time in this study because our aim was to use this immunosensor at a physiological pH condition (pH=7.0 ~ 7.4). Regarding incubation time of antibody-antigen interaction, previous results on antibody-antigen binding showed 30 min − 2 h time incubations appropriate for maximum responses 25 – 27 . .…”

“…The carboxylic acid groups on QDs were activated with 10 mM EDC/NHS solution 23 , and the Au/Cys-GO-modified surface was covalently bonded with the activated QDs for 10 h (Au/Cys-GO/QD) 24 . After washing, the Au/Cys-GO/QD electrode was incubated in a 0.1 M PBS solution (pH 7.0) containing 1 µ g/mL anti-GAPDH for 4 h 25 – 27 . The GAPDH antibody (Ab) was immobilized on the QDs via the amide bonds between the carboxyl group of the QD and the amine group of anti-GAPDH (Au/Cys-GO/QD/anti-GAPDH).…”