MAPLE Assembled Acetylcholinesterase–Polyethylenimine Hybrid and Multilayered Interfaces for Toxic Gases Detection

Abstract

Developing a controlled method for obtaining hybrid enzymatic-based interfaces for sensing application require the use of a multiuse, reusable sensor. By controlling the interface characteristics in terms of the surface chemistry, thickness, and roughness, a tailored response toward various toxic compounds can be obtained, regarding both materials used as active surfaces and fabrication methods. Herein, we report a preliminary study on using a laser-based method (i.e., matrix-assisted pulsed laser evaporation, or MAPLE) for obtaining active polymeric–enzymatic interfaces as hybrid or layered coatings for detecting toxic vapors. The MAPLE fabrication consisted of the simultaneous alternating evaporation of layers of polyethylenimine (PEI) and acetylcholinesterase (AchE) in order to obtain active surfaces as both hybrid PEI-AchE and a PEI/AchE layered coating, respectively. The deposition processes of the polymer and enzyme were carried out using a double-target system and a Nd:YAG pulsed laser, operating at 0.45 J/cm2 fluences with a wavelength of 266 nm and a repetition rate of 10 Hz. Fourier transform infrared spectroscopy revealed no significant changes in the functional groups of both hybrid and layered coatings compared with the initial material. The thickness and roughness, as well as the morphologies of the coatings revealed by atomic force microscopy and scanning electron microscopy showed coatings thicker than two μm that had smooth surfaces and average roughness values below six nm. The sensors were tested with simulants for nerve gases and pesticides containing phosphonate ester groups, namely dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP), and a different sensitivity was shown to the selected chemical agents for each of the sensors. The best sensitivities for DMMP and DIMP obtained by using a PEI-AchE coated sensor are 65 kHz and 200 kHz, respectively, whereas the best sensitivity when using multilayered interfaces is 30 kHz and 10 KHz for DIMP and DMMP, respectively.

Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor

“…This type of sensors has attracted attention through their features as small size, low cost, ease of fabrication, fast response, remarkable sensitivity, satisfactory stability, wireless operation [15,16]. SAW sensors have been developed for the detection of hydrogen [15,17] volatile organic compounds [18], ammonia [16], hydrogen sulfide [1], explosives [19], toxic gases [20], etc.…”

Macrophage in vitro Response on Hybrid Coatings Obtained by Matrix Assisted Pulsed Laser Evaporation

“…There are various deposition methods which can be used for coating a surface, from click chemistry to physical simple methods, such as spin-coating, or more complex procedures, such as laser deposition [55][56][57][58][59][60][61][62][63][64][65]. The main disadvantages for most of the techniques are the poor control over thickness and roughness, lack of possibility to include proteins or growth factors within a wide range of synthetic polymeric matrices, or the fact that the methods imply toxic precursors, causing the destruction of the bio-compounds.…”

“…During the deposition process, the laser beam is scanned on the target surface, the laser beam energy being absorbed by the frozen solvent, therefore vaporizing it and transferring the target molecules toward and onto the substrate placed parallel and at a distance of few cm from the target. Depending on the number of pulses and target composition, there is a deposition/growth of a thin film on the surface of the substrate, while the solvent molecules are pumped away [57][58][59][60][61][62][63][64]. Moreover, MAPLE was shown to be an appropriate approach for obtaining hybrid coatings by embedding, in a controlled way, ceramic material, graphene, nanoparticles within a natural or synthetic polymer layer [57][58][59][60][61][62][63][64].…”

ZnO Metal Oxide Semiconductor in Surface Acoustic Wave Sensors: A Review

“…A considerable advantage of this type of sensor is that it is versatile, which allows for adaptation to different applications [ 21 ]. SAW sensors are used for the detection of gases [ 22 , 23 , 24 ], as well as for the detection of liquids or other changes in the environment, such as pressure [ 25 ], humidity [ 26 ], the presence of UV radiation [ 27 ], and for chemical and biological applications [ 28 , 29 ]. In this work, we focused on the study of SAW sensors for gas detection.…”