A Comparison of EIS and QCM NanoMIP-Based Sensors for Morphine.

Roberta D'Aurelio,Elisabetta Mazzotta,Maria Salbini,Ibtisam E Tothill,Francesca Calò,Cosimino Malitesta,Iva Chianella

doi:10.3390/nano11123360

Roberta D'Aurelio, Elisabetta Mazzotta + Show 5 more

Open Access

https://doi.org/10.3390/nano11123360

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Journal: Nanomaterials	Publication Date: Dec 11, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: Cranfield University, University of Salento

Abstract

In this work we have compared two different sensing platforms for the detection of morphine as an example of a low molecular weight target analyte. For this, molecularly imprinted polymer nanoparticles (NanoMIP), synthesized with an affinity towards morphine, were attached to an electrochemical impedance spectroscopy (EIS) and a quartz crystal microbalance (QCM) sensor. Assay design, sensors fabrication, analyte sensitivity and specificity were performed using similar methods. The results showed that the EIS sensor achieved a limit of detection (LOD) of 0.11 ng·mL−1, which is three orders of magnitude lower than the 0.19 µg·mL−1 achieved using the QCM sensor. Both the EIS and the QCM sensors were found to be able to specifically detect morphine in a direct assay format. However, the QCM method required conjugation of gold nanoparticles (AuNPs) to the small analyte (morphine) to amplify the signal and achieve a LOD in the µg·mL−1 range. Conversely, the EIS sensor method was labor-intensive and required extensive data handling and processing, resulting in longer analysis times (~30–40 min). In addition, whereas the QCM enables visualization of the binding events between the target molecule and the sensor in real-time, the EIS method does not allow such a feature and measurements are taken post-binding. The work also highlighted the advantages of using QCM as an automated, rapid and multiplex sensor compared to the much simpler EIS platform used in this work, though, the QCM method will require sample preparation, especially when a sensitive (ng·mL−1) detection of a small analyte is needed.

Highlights

The development of sensors for the detection of small molecules is a challenge for researchers
The results showed that morphine nanoMIP sensor was proportionally responsive to the increasing concentration of the morphine analyte’s conjugation to the gold nanoparticles (AuNPs), while no apparent response was detectable on cocaine nanoMIP sensor
The limit of detection (LOD) of morphine nanoMIP electrochemical impedance spectroscopy (EIS) sensor developed onto screen-printed electrodes (SPE) (0.11 ng·mL−1 ) was equal to the LOD achieved when the same sensor was fabricated on interdigitated electrodes (IDE) (0.11 ng·mL−1 )

Summary

Introduction

The development of sensors for the detection of small molecules is a challenge for researchers. Most small molecules, such as drugs, toxins and environmental pollutants, require an affinity-based platform for their detection. Sensors are analytical devices developed to detect a single or multiple molecules and can be utilized in several diagnostic settings, such as medicine, food, security and environmental science. (1) a molecular receptor ( known as the sensing receptor), able to bind or recognize the analyte of interest; (2) a transducer, able to convert the binding event into a signal; (3) a processor, able to handle the signal such that it can be visualized and analyzed through a dedicated software.

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Conclusion