Comparative Study of Two Surface Techniques of Proteins Imprinting in a Polydopamine Matrix. Application to Immunoglobulin Detection
16 Pages Posted: 10 Jun 2022
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Comparative Study of Two Surface Techniques of Proteins Imprinting in a Polydopamine Matrix. Application to Immunoglobulin Detection
Abstract
A comparison between molecularly imprinted polymer strategies based on the same monomer for large protein detection is rarely performed. Here, immunoglobulin (IgG) was chosen as a protein model. The first approach is based on the cyclic voltammetry (CV) electropolymerization of a mixture of dopamine monomer and IgG template, while in the second route the protein is anchored to the transducer’s surface, via a mixed self-assembled monolayer of mercaptohexanol (MHOH) and mercaptoundecanoic acid (MUDA), prior to CV dopamine electropolymerization. To guarantee the efficiency and accuracy of both approaches, several parameters were optimized mainly the CV cycles’ number, the scan rates value, the ratio of dopamine-monomer to IgG-template, and the nature of the extracting agents. Square wave voltammetry (SWV), hydrophobicity and surface energy measurements were investigated to follow up all surfaces modification steps and IgG detection in the concentration range of 10 -15 to 10 -2 mg.ml -1 . Both strategies exhibited the same limit of detection (LOD =10 -15 mg.ml -1 ).Sensitivities of the designed electrochemical sensors were of order of (7.23 ± 0.53) 10 -5 mA -1 . cm 2 /mg.ml -1 and (8.85 ± 0.27) 10 -5 mA -1 . cm 2 /mg.ml -1 for the molecularly imprinted polymers (MIPs) 1 and 2 respectively. The dissociation constants, estimated from a combined power-law-Hill model at (1.65 ± 0,45) 10 -10 M, and (1.77 ± 0.43) 10 -11 M, confirm the strong binding between the designed MIPs and IgG protein. Contrary with what was reported in literature, both MIPs strategies based on the same monomer polydopamine presented similar sensing performances in term of imprinting factor, sensitivity, reproductibility and LOD values.
Keywords: polydopamine, molecularly imprinted polymer, immunoglobulin (IgG) protein, electrochemical sensors
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