Melamine Acoustic Chemosensor Based on Molecularly Imprinted Polymer Film

Green Synthesis of a Molecularly Imprinted Polymer Based on a Novel Thiophene-Derivative for Electrochemical Sensing

An environmentally friendly and sustainable approach was adopted to produce a molecularly imprinted polymer (MIP) via electropolymerization, with remarkable electrochemical sensing properties, tested in tyrosine (tyr) detection. The 2,2'-bis(2,2'-bithiophene-5-yl)-3,3'-bithianaphtene (BT2-T4) was chosen as functional monomer and MIP electrosynthesis was carried out via cyclic voltammetry on low-volume (20 μL) screen-printed carbon electrodes (C-SPE) in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((BMIM) TFSI). An easy and rapid washing treatment allowed us to obtain the resulting MIP film, directly used for tyr electrochemical detection, carried out amperometrically. The sensor showed a linear response in the concentration range of 15-200 μM, with LOD of 1.04 µM, LOQ of 3.17 μM and good performance in selectivity, stability, and reproducibility. Tyrosine amperometric detection was also carried out in human plasma, resulting in a satisfactory recovery estimation. The work represents the first use of BT2-T4 as a functional monomer for the production of a molecularly imprinted polymer, with a green approach afforded by using a few microliters of a room temperature ionic liquid as an alternative to common organic solvents on screen-printed carbon electrodes, resulting in a valuable system that meets the green chemistry guidelines, which is today an essential criterion in both research and application field.

A rational approach for 3D recognition and removal of L-asparagine via molecularly imprinted membranes

In this study, a L-asparagine (L-Asn) imprinted membranes (L-Asn-MIPs) were synthesized via molecular imprinting for selective and efficient removal of L-Asn. The L-Asn-MIP membrane was prepared by using acrylamide (AAm) and hydroxyethyl methacrylate (HEMA) as a functional monomer and a comonomer, respectively. The membrane was characterized by scanning electron microscopy (SEM) and Fourier Transform infrared spectroscopy (FTIR). The L-Asn adsorption capacity of the membrane was investigated in detail. The maximum L-Asn adsorption capacity was determined as 408.2 mg/g at pH: 7.2, 24 °C. Determination of L-Asn binding behaviors of L-Asn-MIPs also shown with Scatchard analyses. The effect of pH on L-Asn adsorption onto the membrane and also the selectivity and reusability of the L-Asn-MIPs for L-Asn adsorption were determined through L-asparaginase (L-ASNase) enzyme activity measurements. The selectivity of the membrane was investigated by using two different ternary mixtures; L-glycine (L-Gly)/L-histidine (L-His)/L-Asn and L-tyrosin (L-Tyr)/L-cystein(L-Cys)/L-Asn. The obtained results showed that the L-Asn-MIP membranes have a high selectivity towards L-Asn.

Adenine imprinted beads as a novel selective extracellular DNA extraction method reveals underestimated prevalence of extracellular antibiotic resistance genes in various environments

Despite severe threats of extracellular antibiotic resistance genes (eARGs) towards public health in various environments, advanced studies have been hindered mainly by ineffective extracellular DNA (exDNA) extraction methods, which is challenged by trace levels of exDNA and inference from abundant coexisting compounds. This study developed a highly selective exDNA extraction method based on molecular imprinting technology (MIT) by using adenine as the template for the first time. Results suggested that adenine imprinted beads were rough spheres at an average size of 0.39 ± 0.07 μm. They effectively adsorbed DNA in the absence of chaotropic agents, with superior capacity (796.2 mg/g), rate (0.0066/s) and regarding DNA of variable lengths, even the ultra-short DNA (<100 bp). They were also highly selective towards DNA, circumventing the interference of competitive compounds' interference. These properties contribute to efficient exDNA extraction (71 %-119 %) from various environmental samples. Specifically, adenine imprinted beads enabled significantly higher extraction rates of eARGs from river, air and vegetable samples (69 %-95 %) compared to that by commercial DNA extraction products (16 %-62 %). The adenine imprinted beads-based method reveals underestimated eARG levels in the environment and the corresponding risks, and thus will thus be a powerful tool for advanced exDNA research.

An advantageous application of molecularly imprinted polymers in food processing and quality control

In the global market era, food product control is very challenging. It is impossible to track and control all production and delivery chains not only for regular customers but also for the State Sanitary Inspections. Certified laboratories currently use accurate food safety and quality inspection methods. However, these methods are very laborious and costly. The present review highlights the need to develop fast, robust, and cost-effective analytical assays to determine food contamination. Application of the molecularly imprinted polymers (MIPs) as selective recognition units for chemosensors' fabrication was herein explored. MIPs enable fast and inexpensive electrochemical and optical transduction, significantly improving detectability, sensitivity, and selectivity. MIPs compromise durability of synthetic materials with a high affinity to target analytes and selectivity of molecular recognition. Imprinted molecular cavities, present in MIPs structure, are complementary to the target analyte molecules in terms of size, shape, and location of recognizing sites. They perfectly mimic natural molecular recognition. The present review article critically covers MIPs' applications in selective assays for a wide range of food products. Moreover, numerous potential applications of MIPs in the food industry, including sample pretreatment before analysis, removal of contaminants, or extraction of high-value ingredients, are discussed.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

An Update on Molecularly Imprinted Polymer Design through a Computational Approach to Produce Molecular Recognition Material with Enhanced Analytical Performance

Molecularly imprinted polymer (MIP) computational design is expected to become a routine technique prior to synthesis to produce polymers with high affinity and selectivity towards target molecules. Furthermore, using these simulations reduces the cost of optimizing polymerization composition. There are several computational methods used in MIP fabrication and each requires a comprehensive study in order to select a process with results that are most similar to properties exhibited by polymers synthesized through laboratory experiments. Until now, no review has linked computational strategies with experimental results, which are needed to determine the method that is most appropriate for use in designing MIP with high molecular recognition. This review will present an update of the computational approaches started from 2016 until now on quantum mechanics, molecular mechanics and molecular dynamics that have been widely used. It will also discuss the linear correlation between computational results and the polymer performance tests through laboratory experiments to examine to what extent these methods can be relied upon to obtain polymers with high molecular recognition. Based on the literature search, density functional theory (DFT) with various hybrid functions and basis sets is most often used as a theoretical method to provide a shorter MIP manufacturing process as well as good analytical performance as recognition material.

A spot test for direct quantification of acid green 16 adsorbed on a molecularly imprinted polymer through diffuse reflectance measurements

This work describes a novel technique for the direct quantification of Acid Green 16 (AG16) adsorbed on a molecularly imprinted polymer (MIP) through the application of diffuse reflectance spectrophotometry (DRS) directly in a solid material. The MIP was synthesized by a bulk method using 1-vinylimidazole as the functional monomer. To conduct DRS analysis, adsorption assays were performed through the application of the MIP in a solution containing different concentrations of AG16 for 120 minutes; subsequently, the MIP was left to dry and a certain quantity of the polymer was analyzed. Under optimized conditions, a linear concentration range of 1.0 μmol L^-1 to 10.0 μmol L^-1 and limits of detection and quantification of 0.3 μmol L^-1 and 1.0 μmol L^-1, respectively, were obtained. The repeatability and reproducibility of the method were evaluated and RSD values lower than 4% were obtained. Selectivity studies allowed finding imprinting factor values of 1.9, 2.6, 1.1, and 1.1 for AG16, Direct yellow 50, Acid Blue 1, and Brilliant Green, respectively. The proposed method was applied toward the analysis of river water and textile industry effluents. The advantage and novelty of the technique lie in the fact that the amount of the analyte adsorbed on the selective polymer is directly measured on the solid material for AG16 and not indirectly via the remaining solution as it has always been carried out in previous studies reported in the literature. The findings show that the proposed technique is relatively simple, novel and highly versatile for the quantification of analytes adsorbed on MIPs, as well as for the analysis of the material of interest and quantification of diverse analytes in different matrices.

Ramamurthy P. Development of Molecularly Imprinted Conducting Polymer Composite Film-Based Electrochemical Sensor for Melamine Detection in Infant Formula

Simple, fast, and sensitive molecularly imprinted composite thin-film-based electrochemical sensor developed by using in situ co-electropolymerization of aniline and acrylic acid in the presence of melamine as a template is described here. The prepolymerization complex formation was studied by using Fourier transform infrared (FTIR) spectrophotometry, while the film formation was performed and characterized by cyclic voltammetry, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The optimization of important parameters and removal of melamine generated the binding sites in the polymer matrix, which can recognize melamine specifically. Electrochemical measurements were performed to achieve the linear range, the limit of quantification, and limit of detection of 0.1-180, 0.0573, and 0.0172 nM, respectively. The sensitivity of the sensor was attributed to the synergistic effects of amine from aniline and the carboxylic group from acrylic acid to form multiple noncovalent interactions with the template. Melamine-spiked infant formula and raw milk were analyzed by the developed sensor, and the recovery range of 95.87-105.63% with a relative standard deviation of 1.11-2.23% was obtained. The results showed that the developed sensor using the new composite polymer receptor is promising for the online monitoring of melamine in the food industries in the future.

Promoting bioanalytical concepts in genetics: A TATA box molecularly imprinted polymer as a small isolated fragment of the DNA damage repairing system

We demonstrate that a new, stable, artificial TATA (T - thymine, A - adenine) box is recognized by amino acids recognizing the natural TATA box. Here, the former mimicked, as a minimal motif, oligodeoxyribonucleotide interactions with amino acids of proteins involved in repairing of damaged dsDNA. By electropolymerization, we molecularly imprinted non-labeled 5'-TATAAA-3' via Watson-Crick nucleobase pairing, thus synthesizing, in a one-step procedure, the hexakis[bis(2,2'-bithien-5-yl)] TTTATA and simultaneously hybridizing it with the 5'-TATAAA-3' template. That is, a stable dsDNA analog having a controlled sequence of nucleobases was formed in the molecularly imprinted polymer (MIP). The 5'-TATAAA-3' was by the X-ray photoelectron spectroscopy (XPS) depth profiling found to be homogeneously distributed both in the bulk of the MIP film and on its surface. The 5'-TATAAA-3' concentration in the 2.8(±0.2)-nm relative surface area, ~140-nm thick MIP film was 2.1 mM. The MIP served as a matrix of an artificial TATA box with the TATAAA-promoter sequence. We comprehensively characterized this artificial DNA hybrid by the polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Further, we examined interactions of DNA repairing TATA binding protein (TBP) amino acids with the artificial TATA box prepared. That is, molecules of l-phenylalanine aromatic amino acid were presumably engaged in stacking interactions with nucleobase steps of this artificial TATA box. The nitrogen-to‑phosphorus atomic % ratio on the surface of the MIP-(5'-TATAAA-3') film increased by ~1.6 times after film immersing in the l-glutamic acid solution, as determined using the XPS depth profiling. Furthermore, l-lysine and l-serine preferentially interacted with the phosphate moiety of 5'-TATAAA-3'. We monitored amino acids interactions with the artificial TATA box using real-time piezoelectric microgravimetry at a quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy under flow injection analysis (FIA) conditions.

A Surface Plasmon Resonance-Based Optical Fiber Probe Fabricated with Electropolymerized Molecular Imprinting Film for Melamine Detection

Molecularly imprinted polymer (MIP) films prepared by bulk polymerization suffer from numerous deficiencies, including poor mass transfer ability and difficulty in controlling reaction rate and film thickness, which usually result in poor repeatability. However, polymer film synthesized by electropolymerization methods benefit from high reproducibility, simplicity and rapidity of preparation. In the present study, an Au film served as the refractive index-sensitive metal film to couple with the light leaked out from optical fiber core and the electrode for electropolymerizing MIP film simultaneously. The manufactured probe exhibited satisfactory sensitivity and specificity. Furthermore, the surface morphology and functional groups of the synthesized MIP film were characterized by Atomic Force Microscopy (AFM) and Fourier transform infrared microspectroscopy (FTIR) for further insights into the adsorption and desorption processes. Given the low cost, label-free test, simple preparation process and fast response, this method has a potential application to monitor substances in complicated real samples for out-of-lab test in the future.

Cd-doped Sb2O4 nanostructures modified glassy carbon electrode for efficient detection of melamine by electrochemical approach

Cadmium doped antimony oxide (Cd-doped Sb₂O₄) nanostructures (CAO-NSs) were synthesized by a facile hydrothermal method in alkaline phase at low temperature to detect the melamine from aqueous solution. The calcined CAO-NSs were characterized systematically by FE-SEM, EDS, UV/Vis., FTIR spectroscopy, powder XRD, and XPS techniques. The glassy carbon electrode (GCE) was modified with the CAO-NSs and sensing performance towards the selective melamine was explored by the electrochemical approach in phosphate buffer solution. The melamine undergoes a reduction reaction in the presence of CAO-NSs/GCE in PBS. The CAO-NSs/GCE attained the higher sensitivity (3.153μAμM^-1cm^-2) for a wide ranges of concentration (LDR: 0.05nM-0.5mM), an ultra-low limit of detection (LOD: 14.0 ± 0.05p.M.; S/N = 3), long-term stability, excellent repeatability, and reproducibility. This method might represent an efficient way of sensitive sensor development for the toxic melamine and their derivatives for the safety of biomedical and health care fields in broad scales.

Programmed Transfer of Sequence Information into a Molecularly Imprinted Polymer for Hexakis(2,2'-bithien-5-yl) DNA Analogue Formation toward Single-Nucleotide-Polymorphism Detection

A new strategy of simple, inexpensive, rapid, and label-free single-nucleotide-polymorphism (SNP) detection using robust chemosensors with piezomicrogravimetric, surface plasmon resonance, or capacitive impedimetry (CI) signal transduction is reported. Using these chemosensors, selective detection of a genetically relevant oligonucleotide under FIA conditions within 2 min is accomplished. An invulnerable-to-nonspecific interaction molecularly imprinted polymer (MIP) with electrochemically synthesized probes of hexameric 2,2'-bithien-5-yl DNA analogues discriminating single purine-nucleobase mismatch at room temperature was used. With density functional theory modeling, the synthetic procedures developed, and isothermal titration calorimetry quantification, adenine (A)- or thymine (T)-substituted 2,2'-bithien-5-yl functional monomers capable of Watson-Crick nucleobase pairing with the TATAAA oligodeoxyribonucleotide template or its peptide nucleic acid (PNA) analogue were designed. Characterized by spectroscopic techniques, molecular cavities exposed the ordered nucleobases on the 2,2'-bithien-5-yl polymeric backbone of the TTTATA hexamer probe designed to hybridize the complementary TATAAA template. In that way, an artificial TATAAA-promoter sequence was formed in the MIP. The purine nucleobases of this sequence are known to be recognized by RNA polymerase to initiate the transcription in eukaryotes. The hexamer strongly hybridized TATAAA with the complex stability constant K_s^{TTTATA-TATAAA} = k_a/k_d ≈ 10⁶ M^-1, as high as that characteristic for longer-chain DNA-PNA hybrids. The CI chemosensor revealed a 5 nM limit of detection, quite appreciable as for the hexadeoxyribonucleotide. Molecular imprinting increased the chemosensor sensitivity to the TATAAA analyte by over 4 times compared to that of the nonimprinted polymer. The herein-devised detection platform enabled the generation of a library of hexamer probes for typing the majority of SNP probes as well as studying a molecular mechanism of the complex transcription machinery, physics of single polymer molecules, and stable genetic nanomaterials.

Surface enhancement of a molecularly imprinted polymer film using sacrificial silica beads for increasingl-arabitol chemosensor sensitivity and detectability

Sacrificial silica beads, used for increasing the specific surface area of a molecularly imprinted polymer film, improve the performance of the chemosensor.

Study on Dicyandiamide-Imprinted Polymers with Computer-Aided Design

With the aid of theoretical calculations, a series of molecularly imprinted polymers (MIPs) were designed and prepared for the recognition of dicyandiamide (DCD) via precipitation polymerization using acetonitrile as the solvent at 333 K. On the basis of the long-range correction method of M062X/6-31G(d,p), we simulated the bonding sites, bonding situations, binding energies, imprinted molar ratios, and the mechanisms of interaction between DCD and the functional monomers. Among acrylamide (AM), N,N’-methylenebisacrylamide (MBA), itaconic acid (IA), and methacrylic acid (MAA), MAA was confirmed as the best functional monomer, because the strongest interaction (the maximum number of hydrogen bonds and the lowest binding energy) occurs between DCD and MAA, when the optimal molar ratios for DCD to the functional monomers were used, respectively. Additionally, pentaerythritol triacrylate (PETA) was confirmed to be the best cross-linker among divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), trimethylolpropane trimethylacrylate (TRIM), and PETA. This is due to the facts that the weakest interaction (the highest binding energy) occurs between PETA and DCD, and the strongest interaction (the lowest binding energy) occurs between PETA and MAA. Depending on the results of theoretical calculations, a series of MIPs were prepared. Among them, the ones prepared using DCD, MAA, and PETA as the template, the functional monomer, and the cross-linker, respectively, exhibited the highest adsorption capacity for DCD. The apparent maximum absorption quantity of DCD on the MIP was 17.45 mg/g.

An electropolymerized molecularly imprinted polymer for selective carnosine sensing with impedimetric capacity

Functional monomers are designed for the development of a polymer with molecular cavities selective for the carnosine dipeptide recognition and quantification.

Determination of malachite green and leucomalachite green based on electrochemiluminescence of Ru(bpy)32+ at graphene oxide modified glassy carbon electrodes

An electrochemiluminescence (ECL) method for the determination of malachite green (MG) and leucomalachite green (LMG) has been established based on ECL of Ru(bpy)₃²⁺ at the GO-modified GCE.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Inherently chiral macrocyclic oligothiophenes: easily accessible electrosensitive cavities with outstanding enantioselection performances

Linear conjugated oligothiophenes of variable length and different substitution pattern are ubiquitous in technologically advanced optoelectronic devices, though limitations in application derive from insolubility, scarce processability and chain-end effects. This study describes an easy access to chiral cyclic oligothiophenes constituted by 12 and 18 fully conjugated thiophene units. Chemical oxidation of an “inherently chiral” sexithiophene monomer, synthesized in two steps from commercially available materials, induces the formation of an elliptical dimer and a triangular trimer endowed with electrosensitive cavities of different tunable sizes. Combination of chirality with electroactivity makes these molecules unique in the current oligothiophenes literature. These macrocycles, which are stable and soluble in most organic solvents, show outstanding chiroptical properties, high circularly polarized luminescence effects and an exceptional enantiorecognition ability.

Bio-mimetic sensors based on molecularly imprinted membranes

An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported.

Hierarchical Thin Film Architectures for Enhanced Sensor Performance: Liquid Crystal-Mediated Electrochemical Synthesis of Nanostructured Imprinted Polymer Films for the Selective Recognition of Bupivacaine

Nanostructured bupivacaine-selective molecularly imprinted 3-aminophenylboronic acid-p-phenylenediamine co-polymer (MIP) films have been prepared on gold-coated quartz (Au/quartz) resonators by electrochemical synthesis under cyclic voltammetric conditions in a liquid crystalline (LC) medium (triton X-100/water). Films prepared in water and in the absence of template were used for control studies. Infrared spectroscopic studies demonstrated comparable chemical compositions for LC and control polymer films. SEM studies revealed that the topologies of the molecularly imprinted polymer films prepared in the LC medium (LC-MIP) exhibit discernible 40 nm thick nano-fiber structures, quite unlike the polymers prepared in the absence of the LC-phase. The sensitivity of the LC-MIP in a quartz crystal microbalance (QCM) sensor platform was 67.6 ± 4.9 Hz/mM under flow injection analysis (FIA) conditions, which was ≈250% higher than for the sensor prepared using the aqueous medium. Detection was possible at 100 nM (30 ng/mL), and discrimination of bupivacaine from closely related structural analogs was readily achieved as reflected in the corresponding stability constants of the MIP-analyte complexes. The facile fabrication and significant enhancement in sensor sensitivity together highlight the potential of this LC-based imprinting strategy for fabrication of polymeric materials with hierarchical architectures, in particular for use in surface-dependent application areas, e.g., biomaterials or sensing.

Biotin selective polymer nano-films

Background

The interaction between biotin and avidin is utilized in a wide range of assay and diagnostic systems. A robust material capable of binding biotin should offer scope in the development of reusable assay materials and biosensor recognition elements.

Results

Biotin-selective thin (3–5 nm) films have been fabricated on hexadecanethiol self assembled monolayer (SAM) coated Au/quartz resonators. The films were prepared based upon a molecular imprinting strategy where N,N'-methylenebisacrylamide and 2-acrylamido-2-methylpropanesulfonic acid were copolymerized and grafted to the SAM-coated surface in the presence of biotin methyl ester using photoinitiation with physisorbed benzophenone. The biotinyl moiety selectivity of the resonators efficiently differentiated biotinylated peptidic or carbohydrate structures from their native counterparts.

Conclusions

Molecularly imprinted ultra thin films can be used for the selective recognition of biotinylated structures in a quartz crystal microbalance sensing platform. These films are stable for periods of at least a month. This strategy should prove of interest for use in other sensing and assay systems.

Potential-driven chirality manifestations and impressive enantioselectivity by inherently chiral electroactive organic films

The typical design of chiral electroactive materials involves attaching chiral pendants to an electroactive polyconjugated backbone and generally results in modest chirality manifestations. Discussed herein are electroactive chiral poly-heterocycles, where chirality is not external to the electroactive backbone but inherent to it, and results from a torsion generated by the periodic presence of atropisomeric, conjugatively active biheteroaromatic scaffolds, (3,3'-bithianaphthene). As the stereogenic element coincides with the electroactive one, films of impressive chiroptical activity and outstanding enantiodiscrimination properties are obtained. Moreover, chirality manifestations can be finely and reversibly tuned by the electric potential, as progressive injection of holes forces the two thianaphthene rings to co-planarize to favor delocalization. Such deformations, revealed by CD spectroelectrochemistry, are elastic and reversible, thus suggesting a breathing system.

Piezomicrogravimetric and impedimetric oligonucleotide biosensors using conducting polymers of biotinylated bis(2,2'-bithien-5-yl)methane as recognition units

A new conducting polymer of biotinylated bis(2,2'-bithien-5-yl)methane was prepared and applied as the recognition unit of two different biosensors for selective oligonucleotide determination using either electrochemical impedance spectroscopy (EIS) or piezoelectric microgravimetry (PM) for label-free analytical signal transduction. For preparation of this unit, first, a biotinylated bis(2,2'-bithien-5-yl)methane functional monomer was designed and synthesized. Then, this monomer was potentiodynamically polymerized to form films on the surface of a glassy carbon electrode (GCE) and a Au electrode of a quartz crystal resonator (QCR) for the EIS and PM transduction, respectively. On top of these films, neutravidin was irreversibly immobilized by complexing the biotin moieties of the polymer. Finally, recognizing biotinylated oligonucleotide was attached by complexing the surface-immobilized neutravidin. This layer-by-layer assembling of the poly(thiophene-biotin)-neutravidin-(biotin-oligonucleotide) recognition film served to determine the target oligonucleotide via complementary nucleobase pairing. Under optimized determination conditions, the target oligonucleotide limit of detection (LOD) was 0.5 pM and 50 nM for the EIS and PM transduction, respectively. The sensor response to the target oligonucleotide was linear with respect to logarithm of the target oligonucleotide concentration in a wide range of 0.5 pM to 30 μM and with respect to its concentration in the range of 50 to 600 nM for the EIS and PM transduction, respectively. The biosensors were appreciably selective with respect to the nucleobase mismatched oligonucleotides.