Selectivity and Efficiency of Conductive Molecularly Imprinted Polymer (c-MIP) Based on 5-Phenyl-Dipyrromethane and 5-Phenol-Dipyrromethane for Quorum Sensing Precursors Detection

Abstract

Functional polymers that selectively recognize target compounds are developed by imprinting polymerization. In the present paper, two different dipyrromethanes, 5-phenoldipyrromethane (5-pOH-DP) and 5-phenyl-dipyrromethane (5-ph-DP), are synthetized and investigated to develop conductive molecularly imprinted polymer (cMIP) sensors. As target molecules, two homoserine lactone derivatives were templated by an electrochemically driven polymerization process. Acyl-homoserine lactones (AHLs), also called homoserine lactones (HS), are a class of signaling molecules involved in bacterial quorum sensing (QS), which is a strategy of coordination among bacteria mediated by population density. The preparation of cMIP from 5-pOH-DP and 5-ph-DP in the presence of acetyl-homoserine lactone (Acetyl-HS) or carboxybenzyl-homoserine lactone (Cbz-HS) was performed by cyclic voltammetry (CV). The cMIP selectivity and sensitivity were assessed by microgravimetry (QCM). Both series of measurements were performed with the aid of an Electrochemical Quartz Crystal Microbalance (EQCM/QCM). The experimental evidences are discussed with respect to NMR measurements that were conducted to gain insight into the interactions established between monomers and templates. The NMR data interpretation offers preliminary information about the most probable positions involved in interaction development for both molecules and highlights the role of the hydration shell. The QCM-cMIP sensor was able to detect the analyte in the linear range from 10 −8 mol·L −1 to 10 −6 mol·L −1 and a limit of detection (LOD) of 22.3 ng (3σ of the blank signal) were evaluated. QCM rebinding tests demonstrated that cMIP selectivity was driven by the pendant group of dipyrromethane, which was also confirmed by the NMR data.

Imprinting Pentaphyrin on Conductive Electropolymerized Dipyrromethane Films: A New Strategy towards the Synthesis of Photokilling Materials

“…When 1 was added to a solution of 2 or 3 , the potential of the anodic peak (E pa ) of DP's radical cation formation shifted (about +20 mV) in anodic direction, evidencing the interaction between molecules. The homopolymer poly‐DP is expected to grow in characteristic voltage ranges (+0.2–+0.7 V), and this behavior was also observed in the presence of 1 (Figure A).…”

“…Taking this circumstance into account, we then reasoned that dipyrromethanes (DPs), being the synthetic precursors of porphyrogenic photosensitizers, as well as electrochemically polymerizable, would have been promising candidates to establish cooperative interactions with the photoactive molecules, promoting their entrapment in dipyrromethane polymers. DP's electropolymerization proceeds at the pyrrole units, being the pendant group in C5 (Figure , compounds 2 and 3 ) not involved in this process, so remaining available for the entrapment of the photosensitizer through non‐covalent interactions. Depending on the chemical structure of the photosensitizer, the dipyrromethanes could be suitably selected: in fact, the modular synthesis of dipyrromethanes allows the introduction in position 5 of a substituent bearing the most convenient functionality.…”

Direct detection of small molecules using a nano-molecular imprinted polymer receptor and a quartz crystal resonator driven at a fixed frequency and amplitude

“…In addition, there are limitations with cost of production of monoclonal antibodies and specificity, which affects reliability of detection. Electrochemical techniques, including differential pulse voltammetry (DPV) (Jiang et al, 2016) and cyclic voltammetry (CV) (Susmel and Comuzzi, 2017), have been explored for AHL detection using magnetic and electrochemically conductive MIPs respectively. Although the MIPs allow improvement in specificity, cost of production, robustness and long-term stability over antibodies, the need for electroactive biomolecular probe (Selvolini and Marrazza, 2017) and complexity in the set-up makes operation of miniaturised electrochemical biosensing techniques challenging (Mansouri, 2018).…”

Current Advances in the Synthesis of Valuable Dipyrromethane Scaffolds: Classic and New Methods

“…Interestingly, the acidic NH protons of dipyrromethanes can be used as anion sensors with good binding activity and selectivity [25,26,27,28]. Furthermore, polymers based on dipyrromethanes were developed for the molecular recognition of two homoserine lactone derivatives involved in bacterial quorum sensing [29].…”