Spectroscopic Ellipsometry and Quartz Crystal Microbalance with Dissipation for the Assessment of Polymer Layers and for the Application in the Biosensing
I. Plikusiene, V. Maciulis, A. Ramanavicius, A. Ramanaviciene, Spectroscopic Ellipsometry and Quartz Crystal Microbalance with Dissipation for the Assessment of Polymer Layers and for the Application in Biosensing, Polymers, 14 (2022) 1056. https://doi.org/10.3390/polym14051056
Polymers represent materials that are applied in almost all areas of modern life, therefore, the characterization of polymer layers using different methods is of great importance. In this review, the main attention is dedicated to the non-invasive and label-free optical and acoustic methods, namely spectroscopic ellipsometry (SE) and quartz crystal microbalance with dissipation (QCM-D). The specific advantages of these techniques applied for in situ monitoring of polymer layer formation and characterization, biomolecule immobilization, and registration of specific interactions were summarized and discussed.
Figure 1. Scheme of optical Spectroscopic Ellipsometry and acoustic Quartz Crystal Microbalance with Dissipation signals detection in presence of a thin polymer layer on top of the sensor.
Real-time label-free assessment of T7 DNA polymerase immobilization
J. Dronina, D. Plausinaitis, U. Samukaite-Bubniene, A. Ramanavicius, Real-time label-free assessment of T7 DNA polymerase immobilization, Materials Today Nano, 19 (2022) 100232. https://doi.org/10.1016/j.mtnano.2022.100232
Immobilization of DNA-modifying enzymes on any surface is still a complex and challenging task in biotechnology and biosensorics. Therefore, this task very often is crucial, especially in biosensors dedicated to the continuous monitoring of DNA. The novelty and the importance of this study are related to the development of continuously operating biosensors based on DNA-modifying enzymes. In this research, we focused on the real-time monitoring of T7 DNA polymerase immobilization. Quartz crystal microbalance (QCM) was applied for the monitoring of immobilization of T7 DNA polymerase and assessment of analytical signals generated during the action of this enzyme.
Figure 2. Scheme of the time-resolved simultaneous measurement of changes in frequency, energy dissipation, and surface saturation by T7 DNA polymerase during the immobilization process on the Quartz Crystal Microbalance sensor.
Determination of rSpike Protein by Specific Antibodies with Screen-Printed Carbon Electrode Modified by Electrodeposited Gold Nanostructures
M. Drobysh, V. Liustrovaite, A. Baradoke, R. Viter, C.-F. Chen, A. Ramanavicius, A. Ramanaviciene, Determination of rSpike Protein by Specific Antibodies with Screen-Printed Carbon Electrode Modified by Electrodeposited Gold Nanostructures, Biosensors, 12 (2022) 593. https://doi.org/10.3390/bios12080593
The applicability of electrochemical sensing techniques for detecting specific antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike proteins in the blood serum of patient samples following coronavirus disease 2019 (COVID-19) was assessed. Herein, screen-printed carbon electrodes (SPCE) with electrodeposited gold nanostructures (AuNS) were modified with L-Cysteine for further covalent immobilization of recombinant SARS-CoV-2 spike proteins (rSpike). The affinity interactions of the rSpike protein with specific antibodies against this protein (anti-rSpike) were assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods.
Figure 3. Scheme of experimental stages occurring on the SPCE. (1): The formation of SPCE/AuNS by electrodeposition; (2): SPCE/AuNS/SAM formation; (3): the activation of the SPCE/AuNS/SAM by EDC-NHS mixture following SPCE/AuNS/SAM/rSpike formation; (4): ethanolamine blocking of remaining active functional groups and SPCE/AuNS/SAM/rSpike/anti-rSpike immunocomplex formation via the interaction between immobilized rSpike protein and the anti-rSpike antibodies present in the aliquot.
Towards an Electrochemical Immunosensor for the Detection of Antibodies against SARS-CoV-2 Spike Protein
V. Liustrovaite, M. Drobysh, A. Rucinskiene, A. Baradoke, A. Ramanaviciene, I. Plikusiene, U. Samukaite-Bubniene, R. Viter, C.-F. Chen, A. Ramanavicius, Towards an Electrochemical Immunosensor for the Detection of Antibodies against SARS-CoV-2 Spike Protein, Journal of The Electrochemical Society, 169 (2022) 037523. https://doi.org/10.1149/1945-7111/ac5d91
The electrochemical system for the detection of specific antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in blood serum patient samples after coronavirus disease 2019 (COVID-19). For this purpose, the recombinant SARS-CoV-2 spike protein (SCoV2-rS) was covalently immobilized on the surface of the gold electrode pre-modified with the mixed self-assembled monolayer (SAMmix) consisting of 11-mercaptoundecanoic acid and 6-mercapto-1-hexanol. The affinity interaction of SCoV2-rS with specific antibodies against this protein (anti-rS) was detected using two electrochemical methods: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
Figure 4. Scheme of experimental stages: (1) SAMmix layer formation on Au electrode (Au/SAMmix); (2) SAMmix activation by EDC-NHS mixture (Au/SAMmix/EDC-NHS); (3) SCoV2-rS immobilisation and formation of Au/SAMmix/SCoV2-rS sensing structure; (4) BSA binding of remaining activated carboxyl groups; (5) affinity interaction of anti-rS with immobilised SCoV2-rS (Au/SAMmix/SCoV2-rS/anti-rS).
Molecularly Imprinted Polypyrrole-based Sensor for the Detection of SARS-CoV-2 Spike Glycoprotein
V. Ratautaite, R. Boguzaite, E. Brazys, A. Ramanaviciene, E. Ciplys, M. Juozapaitis, R. Slibinskas, M. Bechelany, A. Ramanavicius, Molecularly Imprinted Polypyrrole based Sensor for the Detection of SARS-CoV-2 Spike Glycoprotein, Electrochimica Acta, 403 (2022) 139581. https://doi.org/10.1016/j.electacta.2021.139581
The application of a polypyrrole-based sensor for the determination of SARS-CoV-2-S spike glycoprotein is described. The electrochemical sensor was designed by molecular imprinting of polypyrrole (Ppy) with SARS-CoV-2-S spike glycoprotein (MIP-Ppy). The electrochemical sensors with MIP-Ppy and with polypyrrole without imprints (NIP-Ppy) layers were electrochemically deposited on a platinum electrode surface by a sequence of potential pulses. The performance of polymer layers was evaluated by pulsed amperometric detection.
Figure 5. Scheme of evaluation by chronoamperometry of Pt electrode modified with non-imprinted polypyrrole (NIP-Ppy) and with molecularly imprinted polypyrrole (MIP-Ppy) with SARS-CoV-2-S glycoprotein imprints. Electrochemical measurements were performed in phosphate-buffered saline (PBS) solution, pH 7.4.
Electrochemical sensors based on L-tryptophan molecularly imprinted polypyrrole and polyaniline
V. Ratautaite, E. Brazys, A. Ramanaviciene, A. Ramanavicius, Electrochemical Sensors based on L-Tryptophan Molecularly Imprinted Polypyrrole and Polyaniline, Journal of Electroanalytical Chemistry, 917 (2022) 116389. https://doi.org/10.1016/j.jelechem.2022.116389
The aim of this work was to compare two different conducting polymers (polypyrrole and polyaniline) in the design of the molecularly imprinted polymer (MIP). An l-tryptophan was selected as a template molecule in such MIP-based layers deposited on the graphite electrodes. Further, the MIPs with l-tryptophan imprints were applied in the design of electrochemical sensors for the detection of l-tryptophan. All polymer layers were electrochemically deposited on the electrode surface by the application of potential cycling. The characteristics of all modified electrodes were evaluated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The results demonstrate that the molecularly imprinted polypyrrole MIPpy layer has a greater affinity toward l-tryptophan molecules in comparison with other layers evaluated in this study.
Figure 6. Scheme of evaluation of graphite electrode modified with non-imprinted polypyrrole (NIP-Ppy) and with molecularly imprinted polypyrrole (MIP-Ppy) with l-tryptophan imprints. Electrochemical measurements were performed by differential pulse voltammetry in 40 mM BR buffer solution with 0.1 M of KCl, pH 2.5.
Evaluation of Electrochromic Properties of Polypyrrole/Poly(Methylene Blue) Layer Doped by Polysaccharides
V. Ratautaite, R. Boguzaite, M.B. Mickeviciute, L. Mikoliunaite, U. Samukaite-Bubniene, A. Ramanavicius, A. Ramanaviciene, Evaluation of Electrochromic Properties of Polypyrrole/Poly(Methylene Blue) Layer Doped by Polysaccharides, Sensors, 22 (2022) 232. https://doi.org/10.3390/s22010232
Polypyrrole (Ppy) and poly(methylene blue) (PMB) heterostructure (Ppy-PMB) was electrochemically formed on the indium tin oxide (ITO) coated glass slides, which served as working electrodes. For electropolymerization, a solution containing pyrrole, methylene blue, and a saccharide (lactose, sucrose, or heparin) that served as a dopant. The aim of this study was to compare the effect of the saccharides (lactose, sucrose, and heparin) on the electrochromic properties of the Ppy-PMB layer. Electrochromic properties were analyzed with respect to the changes in absorbance of the layer at two wavelengths (668 nm and 750 nm) by changing the pH of the surrounding solution and the potential between +0.8 V and −0.8 V.
Comparative study of polydopamine and polypyrrole modified yeast cells applied in biofuel cell design
E. Andriukonis, V. Reinikovaite, A. Ramanavicius, Comparative study of polydopamine and polypyrrole modified yeast cells applied in biofuel cell design, Sustainable Energy & Fuels, 6 (2022) 4209-4217. https://doi.org/10.1039/D2SE00634K
Due to high global energy requirements, the research for green-renewable energy has skyrocketed in the past few years. Yeast-based microbial fuel cells (MFC) could serve as a potential alternative energy source.
Redox-active polymers are currently featured as a promising new class of electron mediators with lower cytotoxicity compared to other conventional electron mediators. In this study, we tested two electroconductive polymers, polypyrrole (Ppy) and polydopamine (PDA), which possess good electrical properties and are biocompatible with microorganisms.
Both PDA and Ppy modifications are deemed successful, which is indicated by an increase in the charge transfer from the yeast cells to the electrodes. Overall, our modifications applied shorter incubation times in the polymerization bulk solution and generated a greater electric current of approximately a 5-fold power increase compared to the regular yeast MFCs.
Figure 7. Scheme of the assessment of polydopamine and polypyrrole-modified yeast cells used in the development of biofuel cells.
Development of biofuel cells based on anode modified by glucose oxidase, Spirulina platensis-based lysate and multi-walled carbon nanotubes
R. Žalnėravičius, V. Klimas, A. Naujokaitis, A. Jagminas, A. Ramanavičius, Development of biofuel cell based on anode modified by glucose oxidase, Spirulina platensis-based lysate and multi-walled carbon nanotubes, Electrochimica Acta, 426 (2022) 140689. https://doi.org/10.1016/j.electacta.2022.140689
Bioanode was successfully designed using the chemical oxidized multi-walled carbon nanotubes (CNT) and Spirulina platensis-based lysates that facilitate the electron transfer and reduce the open circuit potential (OCP) drop along the electron transfer pathway. Composition, morphology and chemical modification efficiency of CNT was examined using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and simultaneous thermal analysis (STA) coupled with mass spectrometric (MS) analysis of evolving gaseous species (TG/DTA–MS). The results of this study indicate that glucose oxidase (GOx) immobilized on CNT functionalized with S. platensis-based lysates possess superior electron transfer and reduce the OCP drop along the electron transfer pathway.
Figure 8. Scheme of the bioanode consisting of glassy carbon with polyethyleneimine, multi-walled carbon nanotubes (CNT) and Spirulina platensis-based lysates and used for the development of biofuel cells.