Stimuli-Responsive Templated Polymer as a Target Receptor for a Conformation-Based Electrochemical Sensing Platform

Abstract

The use of highly cross-linked molecularly imprinted polymers as a synthetic target receptor has the limitations of restricted accessibility to the binding sites, resulting in a slow response time. Moreover, such artificial receptors often require additional transduction mechanisms to translate target binding events into measurable signals. Here, we propose the development of a single-chain stimuli-responsive templated polymer, without using any covalent interchain cross-linkers, as a target recognition element. The synthesized polymer chain exhibits preferential binding with the target molecule with which the polymer is templated. Moreover, upon specific target recognition, the polymer undergoes conformation change induced by its particular stimuli responsiveness, namely, the target binding event. Such templated single-chain polymers can be attached to the electrode surface to implement a label-free electrochemical sensing platform. A target analyte, 4-nitrophenol (4-NP), was used as a template to synthesize a poly(N-isopropylacrylamide) (PNIPAM)based copolymer chain which was anchored to the electrode to be used as a selective receptor for 4-NP. The electrode surface chemistry analysis and the electrochemical impedance study reveal that the polymer concentration, the interchain interactions, and the Hofmeister effect play a major role in influencing the rate of polymer grafting as well as the morphology of the polymers grafted to the electrode. We also show that the specific binding between 4-NP and the copolymer results in a substantial change in the charge transfer kinetics at the electrode signifying the polymer conformation change.

Controlling Graphene Wrinkles through the Phase Transition of a Polymer with a Low Critical Solution Temperature

“…When the temperature is increased, LCST polymer becomes more hydrophobic and the aggregation number of LCST polymer increased. [59][60][61] Therefore, the extent of wrinkles on the PDbS-rGO surface could be controlled by the aggregation number of PDbS on the rGO surface depending on temperature. AuNPs were used to prove the mechanism of wrinkles on PDbS-rGO.…”

A Pencil-Lead Immunosensor for the Rapid Electrochemical Measurement of Anti-Diphtheria Toxin Antibodies

“…The parameters employed in the equation were: the number of electrons ( n = 1), Faraday constant (F = 96,485 C mol L −1 ), the concentration of [Fe(CN) 6 ] 4− = 5 × 10 −6 mol cm −3 , and the average diffusion coefficient value of the [Fe(CN) 6 ] 4− in 0.1 mol L −1 KCl = 5.38 × 10 −6 cm 2 s −1 [ 41 ]. The one-way ANOVA test was performed ( n = 3) with significance defined as p < 0.05 to check whether the device-to-device surface variation during the optimization of fabrication or analytical parameters—e.g., type of PLE, biEP and sec-IgG concentrations, serum dilution ratio, and time of exposition—was significant, as done in studies found in the literature [ 42 , 43 ]. Then, a two-tailed Students t -test with a confidence level of 95% was performed for pairwise comparisons.…”

“…Then, a two-tailed Students t -test with a confidence level of 95% was performed for pairwise comparisons. [ 42 , 43 ].…”

Rapid Detection of Anti-SARS-CoV-2 Antibodies With a Screen-Printed Electrode Modified With a Spike Glycoprotein Epitope

“…The intention was to develop an immunosensor utilizing a drop-casting approach with glutaraldehyde (GA) to sensitize the electrode surface. GA has been widely used to modify electrode surfaces due to its introduction of aldehyde functional groups that allow the covalent bonding of compounds containing terminal amino moieties such as EPs [19]. Next, production of the SPE was optimized.…”