All-in-One Device for Synthesis of Surface Imprinted Polymers and Bacteria Detection

Surface imprinted polymers (SIPs) are polymers that present a functionalized surface able to specifically bind a target. SIPs are synthesized in the presence of a template such that after polymerization and removal of the template, cavities or imprints are left on the surface of the polymer. These cavities act as binding sites with a high affinity towards the template used [1,2]. SIPs are being extensively studies thanks to their advantages over other common detection methods such as antibodies. In fact, SIPs are cheap and they have long shelf life thanks to their chemical and physical stability. Application in medical industries or food processing facilities are of big interest. In this work, an all-in-one device (Figure1) is developed: it integrates on one platform both the SIP fabrication process and the following detection step. Electro polymerization [3] is used to create SIPs, imprinted with different bacteria types. The material used for the fabrication of SIPs is pyrrole. A solution of pyrrole monomer (0.1 M), in phosphate buffer (0.2 M, pH 7) is used; electro polymerization is performed with an open source potentiostat (Rodeostat) and the material is deposited on interdigitated titanium electrodes, used to perform impedance spectroscopy measurements, before and after the binding of the target [4]. Titanium interdigitated electrodes are fabricated by lift-off method on a glass substrate (Figure 1). Impedance measurements are performed with a custom-made board based on the AD5933 impedance analyser module. The device is fabricated with a FDM 3D printer and features a base that contains the electronics and controls and an upper lid. The lid is movable and is controlled by four motors: the lid is designed in such a way that a poly-dimethyl-siloxane (PDMS) disposable flow cell can be used to seal the measurement chamber (Figure 1). The PDMS flow-cell fits on the lid on one side and seals the glass slide with the measuring electrodes on the other. The sample analysed is run through the flow-cell and the impedance is monitored. The device is controlled though an Arduino board, integrated as well in the base. The device has been thoroughly tested: is it easy to use and secure thanks to the disposable PDMS cartridge and the leakage proof design. Preliminary data show promising results: SIPs synthesis protocols are being optimised (Figure 1) in order to obtain a highly sensitive superficial poly pyrrole layer. A variation in the polymerization conditions causes different morphologies in the pyrrole layer that can affect the efficiency of the bacteria binding. Results with imprints of different bacteria types will follow. The all-in-one device represent a novel approach to bacteria detection in liquid samples and is valuable especially for its versatility: in principle it can be easily adapted for a multitude of targets such as other common food pollutants or cells in diagnosis applications. [1] O. Hayden, F. L. Dickert – Advanced Materials (2001) 13, 19, 1480-1483 [2]B.van Grinsven et al. – ACS Sensors (2016) 1, 9, 1140-1147 [3] L. Özcan, Y.Sahin – Sensors and Actuators B (2007) 127, 362-369 [4] B. Khadroa et al. - Procedia Engineering (2010), 5, 371-374 Figure 1. Complete device (centre), and details of parts: A) opened base view with components, B) array interdigitated electrode, C) exploded side view of the moving lid and PDMS flow cell, D) detail of PDMS flow cell. E) SEM images of the electro polymerized poly pyrrole layer in PBS solution with cyclic voltammetry and F) with potentiostatic electro polimerization Figure 1