Design of Pyrrole-Based Gate-Controlled Molecular Junctions Optimized for Single-Molecule Aflatoxin B1 Detection

Abstract

Food contamination by aflatoxins is an urgent global issue due to its high level of toxicity and the difficulties in limiting the diffusion. Unfortunately, current detection techniques, which mainly use biosensing, prevent the pervasive monitoring of aflatoxins throughout the agri-food chain. In this work, we investigate, through ab initio atomistic calculations, a pyrrole-based Molecular Field Effect Transistor (MolFET) as a single-molecule sensor for the amperometric detection of aflatoxins. In particular, we theoretically explain the gate-tuned current modulation from a chemical–physical perspective, and we support our insights through simulations. In addition, this work demonstrates that, for the case under consideration, the use of a suitable gate voltage permits a considerable enhancement in the sensor performance. The gating effect raises the current modulation due to aflatoxin from 100% to more than 103÷104%. In particular, the current is diminished by two orders of magnitude from the μA range to the nA range due to the presence of aflatoxin B1. Our work motivates future research efforts in miniaturized FET electrical detection for future pervasive electrical measurement of aflatoxins.

Effect of Adsorption Mechanism on Conduction in Single-Molecule Pyrrole-Based Sensor for AFB1

“…Table I reports the calculated adsorption energies E ads , as defined in equation (1). For completeness, we report the E ads calculated in our previous works [13], [21] in Table SI2. Comparing the results of Table I and Table SI2, we identify the four most stable adsorption configurations: AC1 with X=0 • , Y=45 I.…”

“…We obtained high AFB1 sensitivity in terms of current modulation at the level of a single AFB1 molecule. In addition, in [21], we have theoretically proven an impressive increase of the Au-8PyDT sensitivity through a strongly coupled gate terminal.…”

“…1(f). Compared to our previous works [13], [21], in this work, we consider additional adsorption configurations, which cover all possible AFB1-8PyDT relative orientations. In particular, y rotations with 45 • step, and z rotations with 180 • step are considered.…”

“…The latter operation corresponds to flipping the AFB1 molecule over the 8PyDT. We do not consider intermediate rotation steps in z, since we have already verified that the 8PyDT and AFB1 interaction is more stable when AFB1 is in a π-stack fashion configuration [21] (maximum steric overlap). Moreover, we do not consider additional x rotations, since, considering the 8PyDT bending, it would result in unrealistic atom overlapping between AFB1 and 8PyDT with Pauli and nuclei repulsion.…”

Advanced Field-Effect Sensors

“…Among other contaminants, aflatoxins A1 to G1 have a high level of toxicity, yet the current biosensing detection techniques prevent their pervasive monitoring throughout the agri-food chain. To fill this gap, Mo and coworkers propose a pyrrole-based molecular field-effect transistor (MolFET) as a single-molecule sensor for the amperometric detection of aflatoxins [11]. The device utilizes a single polymeric chain composed of a sequence of eight pyrrole monomers as the channel and detection element, and Au is used as the source and drain.…”