bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of Carbon Electrodes with Mxene (Ti3C2Tx) for Vanadium Redox Flow Batteries
Authors: Teenakul Kavin , Alem Sayed Ali Ahmad Ali Ahmad , Thakur Anupma , Anasori Babak , Khataee Amirreza
Published: February 2024

MXenes, a group of two-dimensional materials, have gained considerable attention in the field of electrochemistry due to their outstanding electrical conductivity, high surface area, and hydrophilicity resulting from their rich surface chemistry. In this study, Ti3C2Tx MXene-coated carbon paper electrodes were prepared through drop-casting and tested for vanadium redox flow batteries (VRFBs). The resulting MXene-coated electrodes demonstrated a significant improvement in the electrochemical activity of the negative electrode of VRFBs (V(II)/V(III)) compared to heat-treated and untreated carbon paper.

The electrochemical activity of the V(II)/V(III) reaction on MXene-coated electrodes was characterized using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The cyclic voltammetry results indicated that the MXene-coated electrodes displayed a peak current ratio (ipa/ipc) closer to 1 than heat-treated and untreated carbon paper. Electrochemical impedance spectroscopy shows that ohmic and charge transfer resistance are significantly reduced, rivaling a heat-treated carbon paper electrode. VRFB tests were conducted using MXene-coated electrodes on the negative side at a current density of 130 mA/cm2. Carbon paper anodes with MXene loading of 0.1 mg/cm2 maintained voltage efficiency and coulombic efficiency above 70% and 95% for 50 cycles, respectively, which is comparable to that of heat-treated carbon paper, whereas using untreated carbon paper, the voltage efficiency dropped below 60%.

Untreated carbon paper electrode has maximum discharge capacities of 77.4 mAh with a capacity loss of 36%. MXene-coated electrodes, on the other hand, showed impressive maximum discharge capacities of 178.8 mAh and a capacity loss of 19%.
Laser Perforated Dual-Scale Porous Electrodes Considering the Interdigitated Flow Field for Vanadium Redox Flow Battery
Authors: Wenrui Lv , Zheng Menglian , Luo Yansong
Published: February 2024

The conflict between the specific surface area and hydraulic permeability of carbon-based porous electrodes limits the further improvement of redox flow battery (RFB) system performance. Dual-scale electrode design is a feasible approach to overcome this contradiction. In this study, we prepared dual-scale electrodes by perforating graphite felts using an infrared laser. Based on the symmetry of the interdigitated flow field structure, we proposed three dual-scale structure designs with different combinations of large and small pores and tested their performance on a vanadium redox flow battery (VRFB) single cell. The results showed that the design with perforations under the center of the rib could increase the maximum power density by approximately 2.4 times compared to the original electrode. Furthermore, to investigate the effect of the large pores formed by laser perforation on the local electrolyte velocity, active species concentration, and reaction rate distribution, we proposed a pore-network model and investigated the influence of different combinations of large and small pores and different operating conditions on overall performance through numerical simulation. The results showed that the optimal combination of large and small pores is related to the flow rate and other operating conditions, and that setting large pores under the rib near the outlet channel is expected to provide more performance gains in VRFBs equipped with interdigitated flow fields under typical operating flow rates.
Towards Operando Secondary Ion Mass Spectrometry Imaging of Lithium Redistribution in Solid-State Lithium-Ion Batteries: Correlation of Structural, Chemical and Electrochemical Characteristics
Authors: Eswara Santhana , Cressa Luca , Wirtz Tom
Published: February 2024

Innovations in lithium-ion batteries rely crucially on the availability of advanced characterization techniques. High-resolution chemical imaging of low-Z elements e.g., lithium (Li) is often difficult in many conventional chemical analysis techniques such as Energy-Dispersive X-ray Spectroscopy. High-resolution Secondary Ion Mass Spectrometry (SIMS) imaging is a well-known technique for the analysis of all elements including isotopes. For this reason, SIMS imaging is used in numerous studies related to Li-ion battery research. While direct imaging of Li in post-mortem battery components is helpful to understand parts of the degradation mechanisms, a complete dynamic view of the evolution of the Li distribution at high resolution during operation (‘operando’) of batteries is required to fully understand the local interfacial processes, charge transport characteristics and the degradation mechanisms. A few reports presenting operando Time-of-Flight SIMS imaging of batteries have recently been published [1], but the lateral resolution demonstrated in these reports is not adequate to study local processes that occur at nanoscale.

In order to demonstrate operando SIMS chemical imaging with sub-20 nm lateral resolution, we developed a novel operando methodology suitable for Focused Ion Beam (FIB)-SIMS imaging and analysis (see Fig. 1). An in-house designed magnetic-sector mass spectrometer [2] attached to a ThermoFisher SCIOS Ga+ FIB is used for SIMS chemical imaging. A special operando sample holder was designed to enable electrochemical cycling of batteries within the FIB-SIMS instrument. The micromanipulator inside the FIB (typically used for preparing thin lamellae for Transmission Electron Microscopy) is used to contact one of the battery electrodes through the operando sample holder and complete the electrical circuit. An external potentiostat is then connected to the instrument to drive the charging/discharging of batteries. The proof-of-concept experiments were performed using Li|Li7La3Zr2O12|Li symmetric half-cells. Galvanostatic cycling was performed in-situ inside the FIB-SIMS instrument until the sample failed. SIMS chemical mapping revealed a redistribution of Li during cycling. Lithium rich phases appeared during cycling which likely percolated through grain-boundaries and pores of the solid electrolyte causing a short-circuit failure. These results validate our methodology for operando analysis of Li-ion batteries with the possibility to obtain SIMS chemical images with sub-20 nm lateral resolution [3].

This work was funded by the Luxembourg National Research Fund (FNR) through the grant INTER/MERA/20/13992061 (INTERBATT).

[1] Y. Yamagishi, et al., J. Phys.
Chem. Lett. 2021, 12, 19, 4623–4627

[2] O. De Castro, et al., Analytical Chemistry, 2022, 94, 30, 10754–10763.

[3] L. Cressa, et al., Analytical Chemistry, 2023, under review.

Figure 1
Unexplored Reaction Pathways of Ethylene Carbonate during Solid Electrolyte Interphase Formation
Authors: Melin Tim , Hou Xu , Gogoi Neeha , Lundström Robin , Berg Erik J.
Published: February 2024

The solid electrolyte interphase (SEI) keeps eluding our grasp. Fundamental understanding of Li-ion battery performance will not be complete until the major underlying reaction pathways of SEI formation and growth have been described.1 Although the SEI has been observed to be a complex and highly diverse matrix of in-/organic crystalline and amorphous aggregates, likely only few compounds are functional, i.e. passivate the electrode while at the same time sustaining the Li+ transport. The aim of the presentation is to provide experimental evidence for hitherto largely unexplored reaction pathways of several commonly observed SEI compounds (such as lithium ethyl dicarbonate, abbr. LEDC) and prove how the formation of the same can be altered by the choice of electrolyte additives. For instance, Electrochemical Quartz Crystal Microbalance with Dissipation monitoring complemented by Online Electrochemical Mass Spectrometry is demonstrated to separate electrochemical from chemical reactions in a multistep SEI formation process.2-3 Based on our experimental findings, the role and implication of each compound (be it LiOH, Li2O, LEDC, etc.) in the SEI formation process will be discussed.4
(Digital Presentation) Electrochemical Study of Mxene-Metal Oxide Composites for the Degradation of PVC-Based Microplastics
Authors: Alom Nur , Yeasmin Habiba , Han Tan Kim , Saidur R , Jamal Mamun
Published: February 2024

Microplastics (MPs) are fragments of any type of plastic less than 5mm in length, and it is harmful to our ocean and aquatic life. In recent years, the prevalence of MPs in aquatic environments has grown to be a serious environmental problem that has recently gained lots of attention [1, 2]. However, there is still a lack of studies on electrocatalytic treatment for an effective breakdown of MPs [3]. Here, Mxene-Metaloxide composites modified graphite electrode-based electro-fenton (EF) technology has been proposed to break down polyvinyl chloride (PVC) MPs. Advanced oxidation processes are widely studied and applied for the decomposition of MPs. Hydroxyl radicals (•OH) were generated by the electro-oxidation (EO) and electro-peroxidation (EO- ) process which has exhibited great capability for catalytic degradation of MPs and converted into H2O and CO2.

In this work, electro-oxidation was carried out in a three-electrode system with an oxygen-saturated environment where Mxene-Metaloxide composites modified graphite electrode, graphite electrode, and Ag/AgCl electrode were used as a working electrode, counter electrode, and reference electrode respectively. Different operating parameters such as electrolyte type, electrolyte concentration, temperature, and reaction time were maintained for EO. Cyclic voltammetry was employed to analyze the catalytic performance of the MXene-TiO2/C modified graphite electrode in the context of the Oxygen Reduction Reaction. The obtained results revealed that the EO process can degrade 54.5% of MPs after potentiostatic electrolysis at -0.7V Ag/AgCl at 80 °C for 6 hours. Fig 1 presents the removal efficiency of PVC MPs in 0.05M Na2SO4 solution. The results from scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and Energy dispersive X-ray spectroscopy (EDX) revealed that the MPs degraded directly into CO2 and H2O. The results of this research showed that such a heterogeneous EF-like technology using Mxene-metal oxide composites modified graphite electrode was hoped to give an eco-friendly technique for treating MPs in wastewater.

References:

1. K. Dey, E. Uddin & M. Jamal, Environ. Sci. Pollut. Res., 2021, 28, 16925-16947

2. K. Dey, M. Rasel, T. Roy, E. Uddin, B. K. Pramanik & M. Jamal, Sci.Total Environ., 2023, 867, 161390

3. K. Dey, M. Jamal &E. Uddin, J. Water Process. Eng., 2023, 52, 103554

Fig. 1. Removal efficiency of MPs in 0.05M Na2SO4 solution.

Figure 1
Electrochemical Framework for Dynamic Tracking of Soil Organic Matter (SOM)
Authors: Dhamu Vikram Narayanan , Paul Anirban , Muthukumar Sriram , Prasad Shalini
Published: February 2024

Soil Health parameters serve as excellent surrogate measures towards assessing environmental quality and understanding effects of climate change mitigation via carbon sequestration. Soil health monitoring in the near past has been highly qualitative and speculative with more recent advancements still trying to fill the void of determining a holistic soil profile through phantom based measurements. In fields and crop-circles, testing methods to perform in-situ profiling however from one lab is likely to vary with another and hence results are not universally compatible. Additionally, these normalized techniques ideally involve empirical approaches, extensive sample preparation which adds on to a temporal factor along with equipment for extraction and subsequently-analysis. Even with the upcoming research breakthroughs in non-destructive approaches like spectroscopy and tomography-based models, there is a barrier in-terms of equipment complexity and availability as well as high costs and high logistical overhead.

There are a wide number of redox systems present in soil that exist in reduced state under ideal conditions (submerged). While Carbon monitoring would be highly beneficial in the field, an overall sense of the organic matter nutrients present in soil denoted as soil organic matter understanding would offer a wholistic manner of surveying soil and environmental health. In this work, faradaic and non-faradaic measurements are utilized to determine threshold changes in soil electrochemical activity due to presence of various electroactive substances present in the matrix. First, a galvanostatic approach using the chronopotentiometry modality was applied to a soil slurry system- ‘test’ sample to which different levels (w/v %) of the following amendments were added to see how the effective charge modulation can be visualized. Utilizing this experimental framework as preliminary information- A hypothesized mechanism of interaction between the RTIL (Room Temperature Ionic-Liquid) modified electrode and the OM functional moieties based on hydrogen bonding and pi-pi interactions captured using charge-based (chronocoulometry) and interfacial mapping-based (electrochemical impedance spectroscopy) method is utilized to design and test a first-of-a-kind electrochemical soil organic matter (SOM) sensor.

Figure 1. Chronopotentiometric characterization of soil organic matter using an RTIL modified electrode.

Figure 1
Ultraviolet CMOS Image-Sensor Via Energy Down Shift Mechanism of Blue-Light Emitting Quantum-Dots for Environment Analysis
Authors: Jung Uihyeon , Park Jun-seong , Shim Tae-Hun , Park Jea-Gun
Published: February 2024

The application market of ultraviolet (UV) technology has been growing in various fields such as sanitation, sterilization, medicine, and environment, which lead the increase of the demand for UV sensors. In particular, air pollution management has recently attracted social attention. According to the Ministry of Environment, NO2 accounts for 27.2% of air pollutants. An UV sensor can detect NO2 because NO2 absorbs UV lights. The Si based CMOS image sensor (CIS), which is widely used for light sensing, is not suitable for sensing a UV light because of its low quantum efficiency in UV region. Therefore, conventional UV sensors measure reflected, transmitted, and fluorescent UV by using methods with a high sensitivity to UV lights. However, these UV sensors have a limitation in the location of installation because those are single-cell devices or can measure only a small area of several mm2. Therefore, in our research, we propose the quantum-dot (QD) UV-CIS that overcomes these issues and detects NO2 gas quantitatively by imaging UV lights. In addition, we investigated how to increase quantum efficiency and UV sensitivity in Si-CIS by applying a blue-emitting QD film to conventional CIS, which convert UV to blue light through an energy-down-shift mechanism. The UV-CIS demonstrated much higher sensitivity (maximum 118.9 times) in detecting NO2 gas under UV illumination at 365-nm-wavelength than conventional CIS, as shown in Fig. 1. In addition, the difference in UV sensitivity between the conventional CIS and the UV-CIS increased with decreasing the gas UV intensity, as shown in Fig. 2. In particular, under the UV intensity of 100 μW/cm2, the sensitivity of UV CIS to detect NO2 increased by 118.9 times compared to the conventional CIS. Finally, the difference in the UV sensitivity of conventional CIS and UV-CIS and the sensing mechanism of UV lights in UV-CIS will be presented in detail.

Figure 1
Lithium-Ion Capacitor Characterization Using Optical Fiber Sensors
Authors: Wahl Markus Solberg , Guo Xiaoyang , Lamb Jacob , Boles Steven T , Burheim Odne Stokke
Published: February 2024

With the high power density and long cycle life, lithium-ion capacitors (LICs) are anticipated to fill the performance gap with lithium-ion batteries. As LICs generally has one battery-type electrode with slow kinetics, and one capacitor-type electrode with fast kinetics, the bulk concentration of lithium ions is believed to change significantly. To capture the rapidly changing concentration and analyzing it with regards to the charge and discharge rates will reveal important information about the system.

The lithium-ion concentration is measured with an in-house built fiber-optic sensor setup, see Fig. 1. The fiber is placed between the electrodes (Fig. 1a) and the concentration-dependent reflectivity is measured (Fig. 1b). Calibration of the sensor using known concentrations enables the calculation of the electrolyte concentration with rapid acquisition and high accuracy (Fig. 1c).

Figure 1
Ultrasonic Methods for Characterizing Layered Electrodes of Lithium-Ion Batteries
Authors: Huang Ming , Cegla Frederic , Lan Bo
Published: February 2024

Lithium-ion battery electrodes have a multilayered structure consisting of active porous electrode materials coated on one or both sides of a thin metal current collector. The porosity and tortuosity of the active materials play a vital role in determining the battery's performance metrics, such as energy density and power density. However, existing methods for quantifying these parameters are often limited and cannot be easily applied in a production environment. In this work, we propose two ultrasonic methods based on a newly developed stiffness matrix theory [1] to achieve in-production quantification. The first method establishes a quantitative relationship to link angled ultrasound transmission to the porous parameters of electrodes. This relationship is then used to inversely determine porosity and tortuosity from ultrasonic transmission measurements using a non-contact, air-coupled setup. From the first method, we observe that ultrasound is highly transmissible as guided wave modes are excited in electrodes. Based on this phenomenon, our second method directly excites guided waves in the layers using electromagnetic acoustic transducers (EMATs), enabling us to obtain more accurate measurements with a better signal-to-noise ratio. Both methods have demonstrated good sensitivity to porosity and tortuosity, thus providing accurate quantification using ultrasonic transmission and guided wave results. We anticipate that our methods have the potential to provide real-time online characterization of electrodes during production, which would enable closed-loop control of the manufacturing processes and thus dramatically reduce wastage and improve product quality.

Reference

[1] M. Huang, F. Cegla, and B. Lan, Stiffness matrix method for modelling wave propagation in arbitrary multilayers, http://arxiv.org/abs/2302.12868.
Highly Sensitive Acetylcholine Biosensing Via Chemical Amplification of Enzymatic Processes in Single Track-Etched Nanochannels
Authors: Cayón Vanina M. , Toum Terrones Yamili , Laucirica Gregorio , Fenoy Gonzalo , Cortez M. Lorena , Toimil Molares Maria Eugenia , Trautmann Christina , Marmisolle Waldemar , Azzaroni Omar
Published: February 2024

Neurotransmitters are endogenous chemical messengers that play crucial roles in the transmission, enhancement and conversion of specific signals between neurons and other cells and are considered biomarkers of neurodegenerative diseases.[1] Neurodegenerative diseases cause progressive loss of cognitive and/or motor function and, as life expectancy rises, they imply major challenges for societies with rapidly aging populations.[2] As a result, monitoring neurotransmitters is becoming increasingly relevant in clinical environments. Acetylcholine (Ach) is a neurotransmitter that plays a key role in the communication between neurons in the spinal cord and nerve skeletal junctions in vertebrates. [3] Since an abnormal concentration of Ach has proven to be related to neurodegenerative diseases, novel strategies for highly sensitive and specific Ach (bio)sensing are in great demand.

In this work we present the construction of Ach enzymatic biosensors with remarkable sensitivity by acetylcholinesterase immobilization on polyamine-modified single nanochannels via electrostatic self-assembly. [4] To fabricate bullet-shaped single nanochannels in polyethylene terephthalate (PET), 12 µm thick PET foils are irradiated with a single swift heavy ion. The resulting ion track consists of highly localized damaged material along the ion trajectory and is selectively dissolved in a highly basic aqueous solution under asymmetric conditions to obtain a bullet-shaped channel. The controlled PET hydrolysis exposes carboxylic groups at the channel surface (negative charge at pH < 4), which allows the immobilization of further functional groups to design and construct the biosensor.

Here, we will discuss in detail the sensor design, the applied functionalization strategy, and the performance of the sensor. In short, changes in the surface charge of the nanochannel lead to measurable changes in the transmembrane current in a steady-state configuration. We will show experimental results that evidence that the designed sensor successfully transduces the presence of acetylcholine into measurable ionic signals with a 16 nM low limit of detection.

[1] World Health Organization, Neurological Disorders: Public Health Challenges, World Health Organization Press, Geneva, Switzerland,2007.

[2] L. Gan, M. R. Cookson, L. Petrucelli and A. R. La Spada,Nat. Neurosci., 2018, 21, 1300–1309.

[3] M. Hasanzadeh, N. Shadjou and M. de la Guardia, TrAC, Trends Anal. Chem., 2017, 86, 107–121.

[4] Yamili Toum Terrones, Gregorio Laucirica, Vanina M. Cayón, Gonzalo E. Fenoy, M. Lorena Cortez, María Eugenia Toimil-Molares, Christina Trautmann, Waldemar A. Mamisollé and Omar Azzaroni, Chem. Commun., 2022, 58, 10166
Sensitive Recognition of Acetamiprid with a Unique Electrochromic Molecular Imprinted Polymer Sensor
Authors: Mutlu Esma , Şenocak Ahmet , Demirbaş Erhan , Koca Atif , Akyuz Duygu
Published: February 2024

The development of molecularly imprinted polymers (MIPs) and the applications for them have attracted a great deal of interest during the last two decades. MIPs are generally used in different fields, specially molecularly imprinted electrochemical sensors (MIECS), due to their particular design and specific detection abilities [1]. The advantages of an electrochemical MIP sensor include low cost, easy operation, rapid response time and excellent potential for miniaturization and construction for portable equipment applications [2]. In the scope of this work, we performed that electropolymerization of IrO2 as an electrochromic material on an indium tin oxide (ITO) glass substrate and electrosynthesis on this electrode using pyrrole as a functional monomer in the presence of acetamiprid as template were used to create the electrochromic molecular imprinted polymer sensor (MIP/IrO2/ITO). With the created electrochromic MIP sensor, it is intended to create a selective pesticide sensor by utilizing molecular imprinted polymer (MIP) technology, and to detect with the naked eye by color change depending on the acetamiprid concentration by using electrochromic material. The IrO2/ITO electrochromic film demonstrated magnificent cycle stability (100 cycles), high coloration efficiency (400 cm2 C-1 at 450 nm), and quick coloring/bleaching reaction time (8.60s/7.10s, respectively). By using in-situ spectroelectrochemical measurements, these optical properties of MIP/IrO2/ITO were obtained at various acetamiprid concentrations for quantitative analysis. By using differential pulse voltammetry between -0.2 V and +0.8 V (versus Ag/AgCl in 0.1 M PBS), the sensor performance of MIP/IrO2/ITO was assessed. In an acetamiprid concentration range of 4.29–38.6 nM, the MIP/IrO2/ITO electrode demonstrated linear response with a detection limit of 2.72 nM, sensitivity of 47.2 µA nM-1, and repeatability of 0.87%.

Keywords: Electrochromism; Molecularly imprinted polymer (MIP); Pyrrole; IrO2;Acetamiprid; Electrochemical sensor; Spectroelectrochemistry.

Acknowledgements

This work was supported by The Scientific and Technological Research Council of Türkiye, TUBITAK (Project No:121Z784) as the financial.

References

[1] Cui B., Liub P., Liub X., Liua S., Zhang Z., 2020, Journal of Materials Research and Technology, 9(6):12568–12584.

[2 ]Zaidi S. and Shin J., 2014, Int. J. Electrochem. Sci., Vol. 9.
Novel Amino Acid Based Molecularly Imprinted Polymers as Recognition Elements for Electrochemical Detection of Contaminants of Emerging Concern (CEC)
Authors: Beddok Claire , Calas-Blanchard Carole , Fuks Gad
Published: February 2024

Water pollution is a major issue of this era and the development of new sensors and biosensors for specific detection of contaminants of emerging concern (CEC) is of growing interest. Researchers have taken advantage of different recognition systems such as antibodies or enzymes that can be very specific and sensitive toward their target1. However, those biological molecules tend to be expensive, tedious to obtain in large amount, unstable in changing environments and have a short shelf life. To overcome these issues, synthetic analogues named molecularly imprinted polymers (MIPs) have been used as recognition elements. MIPs are polymers with imprinted nanopores that are able to rebind specifically the chosen target. They have the advantage of being cheaper to prepare in large quantities and display a higher robustness, inertness and resistance than their biological counterpart 2. The library of functional monomers used by researchers to prepare MIPs is quite narrow 3 and their recognition in water can be limited 4. That is why we believe it is interesting to design new functional monomers based on amino acids. Indeed, amino acids are good candidates for recognition agent, as they display a variety of functions that can interact through hydrogen bonds, hydrophobic interaction, Π-Π stacking or cation-Π stacking. As a part of antibodies and enzymes, they are capable of recognition in aqueous environment. We believe that using amino acids could get MIP technology closer to biological selectivity and sensitivity, while keeping it cheap and robust. The preparation of a MIP consists in the polymerization of a functional monomer made from an amino acid and a polymerizable agent in the presence of a template (the target of the recognition system).Integrating the MIP in an electrochemical sensor should provide selective detection of the target.

References:

Valera, E. et al. Application of Bioassays/Biosensors for the Analysis of Pharmaceuticals in Environmental Samples. in Comprehensive Analytical Chemistry vol. 62 195–229 (Elsevier, 2013).

Baggiani, C., Anfossi, L. & Giovannoli, C. MIP-based immunoassays: State of the Art, limitations and Perspectives. Molecular Imprinting
1, 41–54 (2013).

Kadhem, A. J., Gentile, G. J. & Fidalgo de Cortalezzi, M. M. Molecularly Imprinted Polymers (MIPs) in Sensors for Environmental and Biomedical Applications: A Review. Molecules
26, 6233 (2021).

Tse Sum Bui, B., Belmont, A.-S., Witters, H. & Haupt, K. Molecular recognition of endocrine disruptors by synthetic and natural 17β-estradiol receptors: a comparative study. Anal. Bioanal. Chem 2081–2088 (2008).

Figure 1
Controlled Surface Functionalization Using Aryldiazonium Salts for the Development of Aptasensing Platforms
Authors: Florea Ciprian , Onas Andra Mihaela , Pandele Andreea Madalina , Raicopol Matei , Pilan Luisa
Published: February 2024

It is well known that both the aptamer surface density and surface chemistry can have a strong influence on the analytical performance of aptasensors based on target-induced conformational changes1. In this context, we report here an improved protocol for obtaining aptasensing platforms which allows fine-tuning the DNA aptamer surface coverage. First, glassy carbon substrates were functionalized with ethynylphenyl groups through the electrochemical reduction of silyl-protected ethynylphenyl diazonium tetrafluoroborates followed by deprotection with tetrabutylammonium fluoride2. The successful removal of the protecting groups (triisopropylsilyl-, triphenylsilyl- and tris(biphen-4-yl)silyl-) was confirmed by X-ray photoelectron spectroscopy and cyclic voltammetry in the presence of Fe(CN)6
3-/4- as soluble redox probe. Following “click” post-modification with suitable derivatization reagents, the surface coverage with ethynylphenyl groups was assessed using complementary techniques such as XPS, cyclic voltammetry and chronocoulometry. For example, the F/C surface ratio of substrates derivatized with 1-(2,2,2-trifluoroethoxy)-6-azidohexane provided an indication of the functionalization degree, and the integration of Fc/Fc+ voltammetric peaks for substrates modified with N-(6-azidohexyl)ferrocenecarboxamide allowed a quantitative determination of the surface coverage. Both techniques showed a good correlation between the protective group size and the surface coverage with alkyne groups. Likewise, we observed a similar trend for substrates derivatized with azide-modified oligonucleotides, where the surface packing density was determined based on the chronocoulometric response of Ru(NH3)6
3+, a cationic redox probe which binds with the negatively charged phosphate groups from the oligonucleotide backbone. As proof of concept, we further developed an electrochemical molecular beacon aptasensor employing a ferrocene-labeled quinine aptamer. We demonstrate that the aptamer surface density, and ultimately the analytical performance of molecular beacon aptasensors, can be effectively fine-tuned by employing silyl protecting groups of different sizes.

Acknowledgements

This work was supported by a grant from the Romanian Ministry of Education and Research, CNCS-UEFISCDI, project number PN-III-P4-ID-PCE-2020-2474, within PNCDI III.

References

Onaş, A. M., Dascălu, C., Raicopol, M. D. & Pilan, L. Critical Design Factors for Electrochemical Aptasensors Based on Target-Induced Conformational Changes: The Case of Small-Molecule Targets. Biosensors 12, (2022).

Leroux, Y. R., Fei, H., Noël, J.-M. M., Roux, C. & Hapiot, P. Efficient covalent modification of a carbon surface: Use of a silyl protecting group to form an active monolayer. J. Am. Chem. Soc. 132, 14039–14041 (2010).
(Invited) All-3D-Printed Devices for Electrochemical Sensing
Authors: Kokkinos Christos
Published: February 2024

Three-dimensional (3D) printing has gained significant attention in research laboratories, since it provides the end user with the freedom and ability to produce in-house and on-demand specific electrochemical platforms in a fast and affordable way. The most applied 3D-printing technology in the manufacturing of electrochemical sensors is fused deposition modeling (FDM) which is based on the e-printing of the device by thermoplastic filaments. In particular, the use of FDM for the printing of sensors offers noteworthy advantages compared to conventional fabrication technologies, such as desktop-sized equipment, very low capital, operational, and materials costs, easy fabrication process, design transferability (as the respective file format can be transferred through e-mail and printed on every dual extruder 3D printer), and ecofriendliness (since no waste is produced) [1,2].

This presentation will discuss our recent developments of all-3D-printed integrated mini devices and their applications to electrochemical sensing [3-6]. The devices are printed from specific filaments (conductive and non-conductive) at different sizes and shapes, by a dual extruder 3D-printer, in order to fit to the demands of numerous applications. More specifically, all-3D-printed electrochemical microtitration wells for the in-situ and micro-volume quantum dot-based bioassays, as well as a 3D-printed wearable glucose monitoring device in the form of an electrochemical ring will be described. Besides, a 3D-printed wearable device in the form of an electrochemical finger for date rape drugs screening and a 3D-printed microfluidic device modified with metallic film for the trace determination of heavy metals will be presented.

Acknowledgements:I thank the Special Account for Research Grants of National and Kapodistrian University of Athens for the financial support.

References

A. Abdalla and B. A. Patel, Curr. Opin. Electrochem., 20 (2020) 78–81.

E. J. Carrasco-Correa, E. F. Simó-Alfonso, J. M. Herrero-Martínez, M. Miró, TrAC - Trends Anal. Chem., 136 (2021) 116177.

A Baltima, H. Panagopoulou, A. Economou, C. Kokkinos, Anal. Chim. Acta 1159 (2021) 338426.

V. Katseli, M. Angelopoulou, C. Kokkinos, Adv. Funct. Mater., 31 (2021) 2102459.

V. Katseli, A. Economou, C. Kokkinos, Anal. Chem. 93 (2021) 3331−3336.

G. Poulladofonou, C. Freris, A. Economou, C. Kokkinos, Anal. Chem. 94 (2022) 4087−4094.
(Invited) Novel Plasmonic Materials as Fluorescence Enhancers for Biosensing and Bioimaging in Near Infrared Window
Authors: Xie Fang
Published: February 2024

Novel plasmonic nanostructures, which are near-IR active, has been developed in our group as powerful fluorescence enhancers. The technology is highly versatile for ultrasensitive diagnosis and deep tissue imaging-two key areas for future diagnostics. I will present some nanostructures we have designed and developed and then discuss their applications in biosensing and cell imaging in near infrared biological transparency window.
(Invited) Nanoplasmonic Optofluidic Biosensors for Rapid and Precise Immune Functional Analysis in Personalized Immunotherapy
Authors: Chen Pengyu
Published: February 2024

Cytokines, acting as intercellular mediators and modulators, are essential biomolecules that regulate diverse functions within the immune response. The rapid and accurate quantification of cytokine-based immune fingerprints is vital for effectively treating immune-related diseases, particularly in point-of-care settings where immediate treatment decisions depend on precise determinations of an individual patient's immune status. Addressing the pressing need for cytokine immunoassays that offer high sensitivity, throughput, multiplexing capability, and short turnaround times at low system complexity, this presentation will discuss novel plasmonic nanomaterial-based optofluidic cytokine biosensors for immune functional analysis ranging from whole blood to single-cell levels. The multiscale experimental and theoretical research will bridge the gap in fundamental understanding of the immune system, enhancing the applicability, diagnosis, and predictive power for immune diseases. The developed platforms aim to provide biologists and clinicians with the capability to real-time monitor patients' immune statuses, a transformative achievement with immense potential for safe, effective, and personalized immunotherapy.
(Invited) Wearable Intelligent Sensors and Electronic (WISE)- Problem, Progress and Perspective
Authors: Xu Tailin , Zhang Xueji
Published: February 2024

Artificial intelligence (AI) and wearable sensors are crucial in achieving the goal of precision medicine, which is to customize the best treatment for each individual patient. The recent combination of these two fields is improving patient data acquisition and the design of wearable sensors for monitoring health, fitness, and surroundings. Wearable sensors aim to address the limitations of centralized and reactive healthcare by providing individuals with insight into their own physiology. However, the relationship between disease and therapeutic platforms is very complex, making it difficult to analyze their output. Integrating AI can bridge this gap by using pattern analysis and classification algorithms to improve diagnostic and therapeutic accuracy. The future of AI-biosensors (such as AI wearable sweat biosensors, AI ingestible biosensors, AI glass biosensors, AI implantable biosensors, etc.) will mainly focus on AI diagnosis (where the diagnostic algorithm in the microprocessor can verify the sensor output and present diagnostic information), big data processing (using self-contained space for historical data and various necessary parameters of data storage, significantly improving the controller's performance), and self-learning/adaptation (embedded microprocessors with advanced programming functions, allowing the AI-biosensor to reconstruct the structure and parameters according to certain behavioral criteria and have adaptive functions).
(Invited) Metal and Nonmetal Plasmonic Nanostructures for Surface-Enhanced Raman Spectroscopy Detection
Authors: Tang Haibin , Meng Guowen
Published: February 2024

Toxic small molecules such as pesticides, food additives, plasticizers and dyes have been posing increasing threat to human health. Surface-enhanced Raman scattering spectroscopy (SERS) is a powerful sensing strategy for these small molecules with advantages including fast response, high sensitivity and fingerprint identification.

Based on the surface plasmon effect, gold and silver nanostructures are the typical plasmonic sensing materials for rapid detection with SERS. However, the crucial challenges for realizing on-site real detection application is to fabricate reproducible and highly sensitive SERS substrates and portable instrument. We fabricated several long-range ordered sensitive nanostructure arrays based on anodic aluminum oxide templates which could provide reproducible structural patterns. Then, we developed a portable instrument integrated with database of the standard Raman spectra of common contaminants and a software for automatic identification and comparison of the test spectrum with the standard database, which can identify the specific analytes. Combined with the sensitive and reproducible SERS substrates, we realized the on-site and rapid detection of various toxic contaminants.

Recently, as an inexpensive candidate, nonmetal plasmonic materials like oxide semiconductors have attracted increasing interests, which induced by the increase of free charge carriers via introducing oxygen vacancies. We synthesized oxygen-deficient WO3-x and NayWO3-x nanosheets and realized the localized surface plasmon resonance (LSPR) band in visible range (~530 nm) as same as the gold nanoparticles, which is the bluest. Then, SERS detection of dyes has also been realized on nonmetal substrate. Moreover, the plasmonic oxygen-deficient oxides showed wide LSPR tuning window from visible to infrared range and plasmon-driven photocatalysis, which may open potentials for biological applications.
(Invited) Advanced Scanning Probe Microscopy for Studying Biofilm Formation and Single Cell Entities at Electrified Interfaces
Authors: Caniglia Giada , Hellmann Andreas , Daboss Sven , Kranz Christine
Published: February 2024

Advanced scanning probe microscopy techniques such as atomic force – scanning electrochemical microscopy (AFM-SECM) und scanning electrochemical microscopy (SECM) are highly attractive hybrid techniques for studying biomedically relevant samples down to the single entity level. Our group introduced a new type of AFM-SECM probe having a conductive colloid instead of a sharp AFM tip. As this spherical microelectrode, which is located at the end of an electrically insulated AFM cantilever can be easily modified by electrodeposition with e.g., conductive polymers and electrocatalytic layers, single cell force spectroscopy under potential control allows studying adhesion properties [1,2]. Cell adhesion is a crucial parameter not only for developing new materials serving as substrates for neural scaffolds, electrodes, and biomedical devices but also in biofilm formation. Biofilms are well-organized aggregates of bacteria able to attach to and proliferate at almost every type of solid surface resulting in increased resistance to conventional antimicrobial and antibiofouling agents [3].The first attachment of bacterials is a process highly influenced by the nature of the surface, such as hydrophobicity, chemical structure, surface charge, and presence of antimicrobials [4].

In this contribution, we present the potential of various scanning probe microscopy techniques, as suitable tools to locally investigate the early stages of biofilm formation and the effects of various antibiofouling and antimicrobial systems against Escherichia coli and Pseudomonas fluorescens. For example, the properties of polydopamine, a bio-compatible polymer, are studied in respect to early stages of bacterial adhesion in dependence of surface charge density and applied potential [5]. Colloidal conductive AFM probes can also be modified electrocatalytic layers, suitable for detecting signaling molecules and at the same time allow electrochemical force spectroscopy at soft samples like biomedically relevant single entities.

References

[1] P. Knittel, H. Zhang, C. Kranz, G. Wallace and M. Higgins, Nanoscale 8, 4475 (2016).

[2] S. Daboss, J. Lin M. Godejohan, C. Kranz, Anal. Chem. 92, 8404 (2020).

[3] O. Ciofu, C. Moser, P. Østrup Jensen, N. Høiby Nat.
Rev. Microbiol. 20, 621 (2022).

[4] A. Viljoen, et al. J
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Bacteriology, 202, e00125 (2020).

[5] G. Caniglia, A. Teuber, B. Mizaikoff, C. Kranz Anal.
Bioanal. Chem. 415, 2059 (2023).
Strategies for Embedding Electrochemical Sensors and Enzymatic Biofuel Cells into Miniaturized Platforms
Authors: Jeerapan Itthipon
Published: February 2024

Miniaturized bioelectronics have great potential in smart devices and on-body biomedical applications, but their development is hindered by the limited availability of a sustainable energy supply. Enzymatic biofuel cells show promise as a power source, but integrating them into practical platforms presents challenges. To address this, we explore a range of materials and strategies for embedding energy-harvesting devices into flexible platforms. For instance, we present a self-powered bioelectronics mask that includes a biofuel cell, a supercapacitor, and a biosensor for detecting glucose levels, all powered by carbon nanotube-based printed biofuel cells. We have also engineered functional materials and customized inks for flexible, single-enzyme-based energy harvesting and self-powered biosensing devices. Additionally, we introduce a battery-free biosensing system that monitors metabolites through in vivo analysis. A self-powered glucose biofuel cell/biosensor integrated into a small circuit performs energy harvesting, biosensing, and wireless human-body communication, allowing for direct biochemical analysis of metabolic profiles. Furthermore, we developed a lab-in-a-mouth sensing device that analyzes thiocyanate levels directly and noninvasively. Carbon electrodes were screen-printed and integrated with mouthguards, and the resulting sensor demonstrates high sensitivity and selectivity for detecting salivary thiocyanate ions. We also discuss the challenges and opportunities in the fields of biosensors and on-demand sensors to further advance these technologies. It is envisioned that developments in biosensors and bioelectronics have significant potential in modern healthcare, including presymptomatic, preventive, and administrational medicine.
Electrochemical Synthesis of Self-Doped Poly(3,4-ethylenedioxythiophene) and Application to Flexible Biosensors
Authors: Jing Yuxin , Miyai Fumika , Okuzaki Hidenori
Published: February 2024

Wet-processable and highly conductive polymers are promising candidates for key materials in organic electronics. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS), commercially available as a water dispersion of colloidal particles, has potential applications to organic electronics because of its high electrical conductivity, transparency and thermal stability 1). However, the PEDOT:PSS has some technical issues owing to the PSS: The ultra-thin layers thinner than the colloidal particle size is difficult; The PEDOT:PSS colloids aggregate and precipitate when stored for an extended period; The pristine PEDOT:PSS exhibits poor electrical conductivity without secondary dopants such as ethylene glycol and DMSO. Recently, we have developed a novel fully soluble self-doped PEDOT (S-PEDOT) by chemical oxidative polymerization having a high conductivity without secondary dopants 2).

This presentation deals with the first study on synthesis of the S-PEDOT by a facile electrochemical polymerization and characterization by means of cyclic voltammetry (CV), reflection spectroscopy, X-ray diffraction analysis (XRD), and the four-point technique.

The S-PEDOT was electrochemically synthesized at different current densities ranging from 0.5 to 5 mA/cm2. It was found that the electrical conductivity increased with increasing current density and attained as high as 427 S/cm at 5 mA/cm2 which was one order of magnitude higher than those so far reported in the literature. Further investigation has been made to clarify the role and effect of current density on molecular weight, crystallinity, and carrier transport properties in more detail.

For the application to biosensors, flexible organic electronic circuits consisting of working, counter, and reference electrodes were fabricated by line-patterning 3) the S-PEDOT water solution as a conductive ink on a Kapton film as a flexible substrate. The flexible glucose sensor was then fabricated by coating the bioink containing glucose oxidase, ferrocene, and chitosan on the working electrode. It was found that the flexible biosensor successfully worked where the electric current during the CV measurement increased with increasing the glucose concentration.

1) H. Okuzaki ed., PEDOT: Materials Properties and Device Applications, S&T (2012).

2) H. Yano, K. Kudo, K. Marumo, H. Okuzaki, Sci. Adv., 5, eaav9492 (2019).

3) D. Hohnholz, H. Okuzaki, and A. G. MacDiarmid, Adv. Funct. Mater., 15, 51 (2005).
Developing Disintegrable and Biodegradable Sensors Using Nanofiber-Reinforced Water-Borne Polyurethane
Authors: Ghosh Gargi , Bag Atanu , Lee Nae-Eung
Published: February 2024

The development of wearable electronics with stretchable components that can conform seamlessly to human tissues and eventually disappear from the environment when disposed is of increasing interest. The challenge is to create materials that are pliable, tough, stretchable, biocompatible, and disintegrable. Biodegradable materials are promising for this purpose, but most of them are not stretchable or tough enough for use in transient wearable electronics. To address these challenges, we present a novel approach to create biodegradable nanofiber-reinforced water-borne polyurethane (NFR-WPU) with stretchability, toughness, and partial biodegradability. This is achieved by embedding biodegradable composite nanofibers (NFs) of poly(glycerol sebacate):poly(vinyl alcohol) (PGS:PVA) into the WPU matrix, which renders its properties tunable. We optimized the loading amount of NFs into the NFR-WPU and found that it significantly enhanced the toughness by 19 times while maintaining the Young's modulus as low as 3.3 MPa. Moreover, the NFR-WPU substrate has very high fracture toughness and shows excellent biocompatibility. It also has a disintegration rate nine times greater than that of pristine WPU. We fabricated and demonstrated disintegrable and stretchable triboelectric and capacitive touch sensors on the NFR-WPU, which have potential use in transient wearable electronics. In summary, our study offers a promising approach for developing transient wearable electronics with stretchable and biodegradable materials. Our NFR-WPU material has excellent mechanical properties, biocompatibility, and disintegration rate, and our disintegrable and stretchable sensors show great potential for future applications.