Advancements in Hydrogel-Functionalized Immunosensing Platforms

Abstract

Explicit antigen–antibody binding has accelerated the development of immunosensors for the detection of various analytes in biomedical and environmental domains. Being a subclass of biosensors, immunosensors have been a significant area of research in attaining high sensitivity and an ultralow sensing limit to detect biological analytes present in trace levels. The highly porous structure, large surface area, and excellent biocompatibility of hydrogels enabling the retainability of the activity and innate framework of the attached biomolecules make them a suitable candidate for immunosensor fabrication. Hydrogels based on polycarboxylate, cellulose, polyaniline, polypyrrole, sodium alginate, chitosan, and agarose are exploited in conjunction with other nanomaterials such as AuNPs, GO, and MWCNTs to augment the electron transfer during the immunosensing mechanism. Surface plasmon resonance, electrochemiluminescence, colorimetric, and electrochemical assays are different strategies utilized for the signal transduction in hydrogel-based immunosensors during the formation of the antigen–antibody complex. These hydrogel-based immunosensors exhibit rapid response, excellent stability, reproducibility, high selectivity and high sensitivity, a broad range of detection, an ultralow limit of detection, and display results similar to those for the ELISA test. This review propounds different hydrogel-functionalized immunosensing platforms classified on the basis of their signal transduction for the detection of disparate cancer biomarkers (tumor necrosis factor, α-fetoprotein, prostate-specific antigen, carbohydrate antigen 24-2, carcinoembryonic antigen, neuron-specific enolase, and cytokeratin antigen 21-1), hormones (cortisol, cortisone, and human chorionic gonadotropin), human IgG, and ractopamine in animal feeds.

Stimuli responsive dynamic transformations in supramolecular gels

“…Chemical analyte responsive gels have huge potential as molecular sensors, aggregation probes, antibacterial agents, conducting materials and water purifying agents. 212,299,[318][319][320][321][322] The presence of chemical analytes can dramatically alter the gel properties. [323][324][325] A specific example is the Tb 3+ metallogel investigated by Ma et al 326 The hydrogel of 2-(2-butyl-1Hbenzimidazol-1-yl)acethydrazide exhibited weak fluorescence at 480 nm which was significantly increased (B4-fold increase) and red shifted to 498 nm in the presence of 0.3 equivalent of terbium nitrate.…”

Hydrogels and Their Role in Biosensing Applications

“…must be immobilized on a substrate (solid surface, e.g., glass, metal, microbeads, hydrogels, etc.). [29][30][31][32][33] The interaction of the target and the probe are registered physico-chemically and then transduced into a detectable signal. [34] Depending on the detection method, the signal can be amplified, but finally it is processed and displayed.…”

Nanostructure-Based Electrochemical Immunosensors as Diagnostic Tools

“…This immunosensor exhibits a linear range of 0.001-10,000 U/mL with a LOD of 1.54 × 10 −3 U/mL and it could be used in early diagnosis. An alternative is the use of a hydrogel-based immunosensor, a three-dimensional porous material composed by interpenetrating polymer networks (IPNs), characterized by large surface area, excellent hydrophilicity and biocompatibility [109]. Tang et al have coated a GC electrode with a sodium alginate-Pb 2+ -GO (SA-Pb 2+ -GO) hydrogel to detect CA242 [110].…”