Aptamer-Based Impedimetric Assay of Arsenite in Water: Interfacial Properties and Performance

Abstract

In this work, we explore the use of electrochemical methods (i.e., impedance) along with the arsenic-specific aptamer (ArsSApt) to fabricate and study the interfacial properties of an arsenic (As(III)) sensor. The ArsSApt layer was self-assembled on a gold substrate, and upon binding of As(III), a detectable change in the impedimetric signal was recorded because of conformational changes at the interfacial layer. These interfacial changes are linearly correlated with the concentration of arsenic present in the system. This target-induced signal was utilized for the selective detection of As(III) with a linear dynamic range of 0.05–10 ppm and minimum detectable concentrations of ca. 0.8 μM. The proposed system proved to be successful mainly because of the combination of a highly sensitive electrochemical platform and the recognized specificity of the ArsSApt toward its target molecule. Also, the interaction between the ArsSApt and the target molecule (i.e., arsenic) was explored in depth. The obtained results in this work are aimed at proving the development of a simple and environmentally benign sensor for the detection of As(III) as well as in elucidating the possible interactions between the ArsSApt and arsenic molecules.

Preliminary Data on a SERS-Responsive Sensor Based on Metallic Nanostructures Functionalized by Aptamers Specific for Arsenic

“…In all cases the CD spectra of all the tested ONs remained unchanged upon As titration (data not shown): thus, even if the binding with arsenite and arsenate occurred, this did not affect the conformation of the ONs, including the parent aptamer Ars3. This result was in net disagreement with various works reporting that marked CD changes occurred after arsenic addition to Ars3 [9], [11], [15], [16].…”

“…From this first work, Ars3 has been explored also in subsequent researches on arsenic sensors. In all cases, the aptamer was used as such, that is containing the random part plus the two flanking constant regions (which were generally removed) required for the PCR (polymerase chain reaction) step of the SELEX, and no attempt to optimize it, in terms of size and sensor-efficiency, or to elucidate its binding mechanism with arsenic has been ever described [9][10][11][12][13][14][15][16][17]. Furthermore, even if the detection limit for As sensors previously reported exploiting Ars3 was generally low, the assembly of the probe and the detection methodologies were very complex and not suitable for the development of portable in situ devices.…”

Simultaneous characterization of physical, chemical, and thermal properties of polymeric multilayers using infrared spectroscopic ellipsometry

“…The range of thicknesses that might be obtained through IRVASE is large. Thicknesses as small as ~1 nm may be obtained [30]. The thickness of thick LbL films (more than 500 μm) may be evaluated using IRVASE if the sample is homogenous and with minimal roughness.…”

“…The versatility of this technique is also demonstrated with the possibility of coupling other accessories to the equipment, such as a temperature stage, which allows the study of changes in film chemistry and thickness with respect to temperature [25]. Today, literature has reported the use of IRVASE to measure the dielectric function of substrates [26][27], determining the optical constants for lubricants [28] and polymers [23], to measure concentration profiles of doped silicon wafers [29], to evaluate physical-chemical properties of thin spin cast films [24], in studies of thermal stability of protein monolayers and multilayers deposited by drops over silicon substrates [25] and in the detection of inorganic compounds in nanolayers between 1 – 5 nm of thickness, like it was reported in our most recent work [30]. Only one recent report is available in the literature using IRVASE as a complementary technique to characterize LbL films composed of poly (ethylenimine) and poly (acrylic acid) [31].…”

Construction of Time-Resolved Luminescence Nanoprobe and Its Application in As(III) Detection

“…Unlike traditional solid-phase calcination, ZGO:Mn nanorods prepared using hydrothermal synthesis disperse better in aqueous solutions, which is more suitable for the fabrication of As(III) probes [21]. Recently, with the development of the theory, more and more optical sensors for As(III) detection based on various principles have been designed [22], including fluorescent [23][24][25][26], colorimetric [27,28], resonance Rayleigh scattering (RRS)-based [29], chemiluminescence-based [30,31] and electrochemical [31] methods. However, there are few reports of the development of As(III) time-resolved luminescence probes based on aptamer-modified PLNPs.In this study, we constructed a time-resolved luminescence probe for As(III) using green florescent PLNPs as signal emitters, based on the specific binding mechanism of the aptamer for As(III).…”