Serafina Cotrone

Electrolyte‐Gated Organic Field‐Effect Transistor Sensors Based on Supported Biotinylated Phospholipid Bilayer

Anchored, biotinylated phospholipids forming the capturing layers in an electrolyte-gated organic field-effect transistor (EGOFET) allow label-free electronic specific detection at a concentration level of 10 nM in a high ionic strength solution. The sensing mechanism is based on a clear capacitive effect across the PL layers involving the charges of the target molecules.

Carbon based materials for electronic bio-sensing

Bio-sensing represents one of the most attractive applications of carbon material based electronic devices; nevertheless, the complete integration of bioactive transducing elements still represents a major challenge, particularly in terms of preserving biological function and specificity while maintaining the sensors electronic performance. This review highlights recent advances in the realization of field-effect transistor (FET) based sensors that comprise a bio-receptor within the FET channel. A birds-eye view will be provided of the most promising classes of active layers as well as different device architectures and methods of fabrication. Finally, strategies for interfacing bio-components with organic or carbon nano-structured electronic active layers are reported.

Interfacial electronic effects in functional biolayers integrated into organic field-effect transistors

Biosystems integration into an organic field-effect transistor (OFET) structure is achieved by spin coating phospholipid or protein layers between the gate dielectric and the organic semiconductor. An architecture directly interfacing supported biological layers to the OFET channel is proposed and, strikingly, both the electronic properties and the biointerlayer functionality are fully retained. The platform bench tests involved OFETs integrating phospholipids and bacteriorhodopsin exposed to 1–5% anesthetic doses that reveal drug-induced changes in the lipid membrane. This result challenges the current anesthetic action model relying on the so far provided evidence that doses much higher than clinically relevant ones (2.4%) do not alter lipid bilayers’ structure significantly. Furthermore, a streptavidin embedding OFET shows label-free biotin electronic detection at 10 parts-per-trillion concentration level, reaching state-of-the-art fluorescent assay performances. These examples show how the proposed bioelectronic platform, besides resulting in extremely performing biosensors, can open insights into biologically relevant phenomena involving membrane weak interfacial modifications.

Volatile general anesthetic sensing with organic field-effect transistors integrating phospholipid membranes

The detailed action mechanism of volatile general anesthetics is still unknown despite their effect has been clinically exploited for more than a century. Long ago it was also assessed that the potency of an anesthetic molecule well correlates with its lipophilicity and phospholipids were eventually identified as mediators. As yet, the direct effect of volatile anesthetics at physiological relevant concentrations on membranes is still under scrutiny. Organic field-effect transistors (OFETs) integrating a phospholipid (PL) functional bio inter-layer (FBI) are here proposed for the electronic detection of archetypal volatile anesthetic molecules such as diethyl ether and halothane. This technology allows to directly interface a PL layer to an electronic transistor channel, and directly probe subtle changes occurring in the bio-layer. Repeatable responses of PL FBI-OFET to anesthetics are produced in a concentration range that reaches few percent, namely the clinically relevant regime. The PL FBI-OFET is also shown to deliver a comparably weaker response to a non-anesthetic volatile molecule such as acetone.

Microcantilevers and organic transistors: two promising classes of label-free biosensing devices which can be integrated in electronic circuits

AbstractMost of the success of electronic devices fabricated to actively interact with a biological environment relies on the proper choice of materials and efficient engineering of surfaces and interfaces. Organic materials have proved to be among the best candidates for this aim owing to many properties, such as the synthesis tunability, processing, softness and self-assembling ability, which allow them to form surfaces that are compatible with biological tissues. This review reports some research results obtained in the development of devices which exploit organic materials’ properties in order to detect biologically significant molecules as well as to trigger/capture signals from the biological environment. Among the many investigated sensing devices, organic field-effect transistors (OFETs), organic electrochemical transistors (OECTs) and microcantilevers (MCLs) have been chosen. The main factors motivating this choice are their label-free detection approach, which is particularly important when addressing complex biological processes, as well as the possibility to integrate them in an electronic circuit. Particular attention is paid to the design and realization of biocompatible surfaces which can be employed in the recognition of pertinent molecules as well as to the research of new materials, both natural and inspired by nature, as a first approach to environmentally friendly electronics. FigureRepresentative scheme of biorecognition in Organic Transistor and Microcantilever devices

Solution processed ter-anthrylene-ethynylenes for annealing-activated organic field-effect transistors: a structure–performance correlation study

OFETs based on new solution-processed ester functionalized 9,10-ter-anthrylene-ethynylenes show a mobility increase of four orders of magnitude, leading to mobilities as high as 4.9 × 10−2 cm2 V−1s−1 if the deposited film is annealed before contact deposition. The behavior is ascribed to an increase in film order at the dielectric/semiconductor interface as revealed by X-ray studies.

Spectrochemical Characterization of Thin Layers of Lipoprotein Self-Assembled Films on Solid Supports Under Oxidation Process

Low density lipoprotein self-assembled layers on gold support, proposed as model for oxidation studies, were subjected to oxidation processes using different oxidative agents: 2,2′-Azobis(2methylpropionamidine)dihydrochloride, atmospheric oxygen, and metal-induced oxidation. The freshly prepared and the oxidized layers were characterized by X ray photoelectron spectroscopy (XPS), Fourier-Transformed infrared spectroscopy, and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry to discriminate the effects of oxidative reagents. Data obtained from FTIR and MALDI spectra proved the lipoperoxide formation subsequent to reactive oxygen species attack and the opportunity to use the model to discriminate between oxidation toxicity.

Field Effect Transistor Sensing Devices Employing Lipid Layers

Field-Effect Transistors comprising layers of lipids have been developed and characterized from the electrical point of view. Lipid layers-OTFT are proposed as novel devices for perspective application in the detection of analytes from aqueous samples.

Innovative electronic biosensors based on organic thin film transistors

To satisfy the demand for fast and smart analytical systems a great interest has been focused on the study and development of novel bio-sensing devices. Electronic transduction can open new perspectives for point-of-care diagnosis actuated by fast, sensitive, selective and reliable biosensors. Recently our group demonstrated the feasibility of the coupling of a biological recognition element to an organic field-effect device [3, 4]. As a further step, investigations on different deposition techniques have been developed, to improve the adhesion and the homogeneity of the biological element onto the organic semiconductor.

Use of lipid bilayers as support for biomolecules integration in OTFT biosensors

Organic thin film transistor (OTFT) technology can be implemented to develop cost-effective and label-free bio-affinity sensor chips, having a field-effect transport directly coupled to a bio-sensing process, useful to high-throughput testing and point-of-care applications. Biological recognition elements such as antibodies or other proteins can be integrated in OTFT devices to confer specificity. In this study the use of lipid bilayers as support for biomolecules immobilization is investigated. Preliminary results in terms of electrical resistance and capacitance of the lipid bilayers are presented.