# Potentiometric Biosensor Based on Artificial Antibodies for an Alzheimer Biomarker Detection
## 4 Conclusions  
This research describes the development and characterization of potentiometric sensors based on MIP for the determination of the target molecule A\(\beta\)-42.  
In essence, MIP technology allows for the production of synthetic receptors with binding constants comparable to those of natural receptors but capable of withstanding extreme conditions, such as temperature, pressure, pH and organic solvents. In theory, synthetic antibodies are very stable and robust, much cheaper than natural receptors and can be stored for long periods of time. The proper selection of the imprinting method is critical, as is the type of polymer material. Conventional bulk imprinting has proven to be a complicated process. Major difficulties include a reduced mass transfer and entrapment of the analyte in the polymer matrix, compromised integrity of the polymer structure, limited solvent choices and formation of heterogeneous binding sites. These limitations can be overcome by surface polymerizations. In surface imprinting, nanometer-sized molecules are immobilized on the surface of nanostructured materials.  
In this work, the synthesis of a nanostructured molecular imprint polymer immobilized on a SWCNT surface is described. Due to its small size, a high surface-to-volume ratio is achieved, which favors miniaturization. This material showed good affinity and sensitivity for the A\(\beta\)-42 peptide.  
The imprinted material was immobilized on a PVC membrane and evaluated by potentiometry. The potentiometric response was controlled by the properties of the medium in which the membranes were located so that the pH had a major influence. In alkaline, more precisely at pH 8.0, the membranes showed good analytical properties. Overall, these membranes have several advantages: a simple design, low response time, and good  
\begin{table}
\begin{tabular}{c c c} \hline
**[Ag–42], (\(\upmu\)g/mL)** & **Recovery (\%)** & **Error (\%)** \\ \hline
1.31 & 103.5 \(\pm\) 0.083 & 3.54 \(\pm\) 0.08 \\
1.08 & 107.5 \(\pm\) 0.22 & 7.49 \(\pm\) 0.11 \\
0.71 & 102.3 \(\pm\) 0.08 & 2.34 \(\pm\) 0.08 \\ \hline \end{tabular}
\end{table}
Table 2: Analytical application of the sensor in spiked serum samples in serum pH 8.0.  
selectivity. Moreover, this method proved to be simple, cheap, accurate and cost effective in terms of the reagent and equipment consumption. Further developments are needed to reduce the LOD of the imprinted materials.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12073625/s1](https://www.mdpi.com/article/10.3390/app12073625/s1)]([https://www.mdpi.com/article/10.3390/app12073625/s1](https://www.mdpi.com/article/10.3390/app12073625/s1)), Table S1: Log KPT for different interfering species in MOPS pH 8.0; Table S2: Electrochemical biosensors for the detection of AD peptide biomarkers using nanomaterials as electrode modifiers or as labels published over the last ten years. References [31; 32; 39; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81] are cited in the Supplementary Materials.  
Conceptualization, F.T.C.M. and M.G.F.S.; methodology, S.C.R. validation, S.C.R. formal analysis, F.T.C.M. and S.C.R.; investigation, S.C.R.; resources, F.T.C.M. and M.G.F.S.; writing--original draft preparation, F.T.C.M.; writing--review and editing, F.T.C.M., M.G.F.S. and R.F.; supervision, F.T.C.M., R.F. and M.G.F.S.; project administration, F.T.C.M. and M.G.F.S.; funding acquisition, F.T.C.M. All authors have read and agreed to the published version of the manuscript.  
0624_2 IQBIONEURO_6_E, 2 QBioneuro, Impulso de una red de I + i en quimica biologica para diagnostico y tratamiento de enfermedades neurologicas EP-INTERREG V A Espaa Portugal (POCTEP).  
Not applicable.  
The authors declare no conflict of interest.