Label-Free Electrochemical Immunosensor Made with Tree-like Gold Dendrites for Monitoring 25-Hydroxyvitamin D3 Metabolite

Abstract

Flexible, fully printed immunosensors can meet the requirements of precision nutrition, but this demands optimized molecular architectures to reach the necessary sensitivity. Herein, we report on flexible and label-free immunosensor chips made with tree-like gold dendrites (AuDdrites) electrochemically formed by selective desorption of l-cysteine (L-cys) on (111) gold planes. Electrodeposition was used because it is scalable and cost-effective for a rapid, direct growth of Au hyperbranched dendritic structures. The 25-hydroxyvitamin D3 (25­(OH)­D3) metabolite was detected within 15 min with a limit of detection (LOD) of 0.03 ng mL–1. This high performance was possible due to the careful optimization of the electroactive layer and working conditions for square wave voltammetry (SWV). Electrocrystallization was manipulated by controlling the deposition potential and the molar ratio between HAuCl4 and L-cys. Metabolite detection was performed on human serum and saliva samples with adequate recovery between 97% and 100%. The immunosensors were stable and reproducible, unresponsive to interference from other molecules in human serum and saliva. They can be extended for use as wearable sensors with their mechanical flexibility and possible customization.

Electrochemical Paper-Based Nanobiosensor for Rapid and Sensitive Detection of Monkeypox Virus

“…Meanwhile, CV for the AuNS electrode shown in Figure 2D (red line) exhibited a typical behavior of gold material, allowing us to note the presence of an anodic peak related to gold oxidation (∼0.97 V) and a reduction peak (∼0.65 V), which can be attributed to the reduction of gold oxide to metallic gold (Au 0 ). 49,50 The structural characterizations of LSG and LSG/AuNS were investigated by XRD measurements, and the results can be found in Figure 2E. The LSG electrode presented a peak at 2Θ value of approximately 25.9°, which is related to the diffraction (002) plane of the graphene-derived nanomaterial.…”

Rational Design of Trident Aptamer Scaffold for Rapid and Accurate Monitoring of 25-Hydroxyvitamin D3 Metabolism in Living Cells

“…On the other hand, excessive vitamin D can cause kidney stone formation and renal impairment . Various analytical methods have been developed to detect 25­(OH)­VD3, − but many of these methods are still labor-intensive, time-consuming, and expensive, making them unsuitable for widespread use in clinical settings. Therefore, there is still an urgent need for more strategies that can be used for rapid and accurate diagnosis of 25­(OH)­VD3 abnormality.…”

“…Aptamers, obtained through the systematic evolution of ligands by exponential enrichment (SELEX) screening, are single-stranded DNA or RNA molecules that can bind tightly and specifically to target molecules. − Aptamer-based biosensors, which exhibit high sensitivity and simplicity, have been extensively developed to detect disease markers, including electrochemical, − localized surface plasmon resonance, and fluorescence sensors. , In 2017, Gu’s group developed the 25­(OH)­VD3 aptamers by SELEX, and the dissociation constants ( K d ) of the aptamer VDBA14 were determined to be 11 nM . Inspired by these encouraging developments, researchers are now focusing on developing more sensitive and reliable detection methods that allow the monitoring of 25­(OH)­VD3 biotransformation in cells. , However, using aptamer-based assays for detecting 25­(OH)­VD3 in living cells has limitations, including uneven distribution and inconsistent spatial orientation during immobilization, as well as impaired binding epitopes due to steric hindrance and random orientation. − Increasing immobilized aptamer numbers can help, but high density can lead to hindrance. Therefore, new methods are still needed for monitoring 25­(OH)­VD3 metabolism in living cells with improved sensitivity and accuracy.…”

“…21 Inspired by these encouraging developments, researchers are now focusing on developing more sensitive and reliable detection methods that allow the monitoring of 25(OH)VD3 biotransformation in cells. 8,9 However, using aptamer-based assays for detecting 25(OH)-VD3 in living cells has limitations, including uneven distribution and inconsistent spatial orientation during immobilization, as well as impaired binding epitopes due to steric hindrance and random orientation. 22−25 Increasing immobilized aptamer numbers can help, but high density can lead to hindrance.…”

Ultrasensitive Determination of Glial-Fibrillary-Acidic-Protein (GFAP) in Human Serum-Matrix with a Label-Free Impedimetric Immunosensor

“…As a result of their excellent electron transfer kinetics, gold NPs with modified electrodes in various shapes and sizes have been widely used as a backing material for electrochemical analysis. The combination of L-cys and Au NPs is likely to exhibit appealing qualities due to the synergistic impact of L-cys and Au NPs, such as high effective surface area and stability compared with those without Au NPs [ 16 ]; however, to produce a biosensor with improved features, such as stability and selectivity, the sensing molecule’s attachment and interaction with the solid surface are critical [ 17 , 18 ]. Self-assembled monolayers (SAMs) enable the attachment of biomolecules to the surface of an electrode, and electrochemical detection techniques result in cheap costs, quick reaction times, enhanced sensitivity, and enhanced mobility [ 18 , 19 , 20 ].…”