Knowledge on the behavior of an individual cell is of critical importance because even genetically identical cells showed large variation. It has become an essential project to design and develop single-cell in-situ analysis techniques with high sensitivity, high selectivity, and high spatiotemporal resolution in the field of analytical chemistry. Aiming at urgent challenges in the field of single-cell analysis, such as the low sensitivity and background interference, we proposed many new mechanisms for electrochemical analysis and constructed a lot of high-sensitive optoelectronic micro-nano interfaces. With these new optoelectronic micro-nano interfaces, the applicant developed a series of single-cell imaging techniques to solve scientific problems. For example, the applicant proposed Fermi level-charge theory that straightly decreases the detection limit of faraday current to attoampere level, six orders smaller than current methods, which allows for the observation of single-molecular level electron transfer events. we elucidate the intracellular factors that determine this output limit by monitoring the respiratory-driven shrinking kinetics of a single magnetite nanoprobe immobilized on a single Shewanella oneidensis MR-1 cell with plasmonic imaging. We proposed label-free structural color microscopy and demonstrated that Shewanella oneidensis MR-1 cells show unique structural color scattering, changing with the redox state of cytochrome complexes in the outer membrane. it provides a potential platform for further exploring the electron transfer mechanism of subcellular structure.

Chronic kidney disease (CKD) has emerged as a significant contributor to morbidity and mortality in the 21st century. A bioengineered paper device has been created for the purpose of quantifying albumin in physiological samples. The paper surface was activated, and antibodies that are specific to the targeted biomarker were immobilized on the modified paper surface. Following the change, each subsequent step was characterized using FTIR, XPS, SPM, and optical analysis. Additionally, the device model was created via CAD files, and a three-dimensional cascade device was manufactured with an integrated continuous light source in order to establish a suitable and regulated environment for picture processing. Following the introduction of the sample onto the bioengineered paper, the subsequent occurrence involves the antigen–antibody reaction. The study of the image involved the utilization of an optical method, which entailed the identification of the image's area and the intensity of its color. The developed immunosensor's linear dynamic range has been reported to be 1–60 mg/mL, with a detection limit of 0.049(±0.002) mg/mL, spanning both the clinical and normal range of albumin in physiological samples. Furthermore, an assessment was conducted to determine the specificity of the immunosensor toward various compounds present in serum. The outcomes of this evaluation demonstrated a low level of cross-reactivity and a high level of performance. The device exhibited high precision and accuracy in determining the levels of albumin in the serum sample with the recovery % being between 88.14 and 97.70. The developed device has the potential to be employed in primary health care centers.

The issue of controlling antibiotic residues poses a severe threat that the society urgently needs to address. An effective way to enhance antibiotic control would be implementing a rapid, sensitive, and cost-effective detection method [1]. In this work, we report the development of a novel system based on integrating localized surface plasmon resonance (LSPR) and quartz crystal microbalance (QCM) methods in a fluidic chamber. We performed penicillin (PEN) detection utilizing DNA thiolated aptamers as receptors chemisorbed on gold nanoparticles (AuNPs, diameter 80 nm) immobilized on quartz crystal (Fig. 1A). The sensing area was incubated with PEN in a 1-100 µM concentration range. This resulted in a decrease in the resonant frequency of QCM, as well as changes in the LSPR signal observed as a shift of the extension peak (Fig. 1B). Subsequently, the sensor specificity was determined using oxytetracycline, kanamycin, and ampicillin. The results demonstrate that the sensor specifically binds PEN. Although we have not reached high detection limits in the nM range, this work shows the preliminary results of a correlative, and real-time detection system for biosensing. Furthermore, the advantage of a simultaneous measurement is that when a detection is made, it can be confirmed by double measurement. The sensitivity of the two techniques can also be compared. With LSPR, the wavelength shift was proportional to the penicillin concentration in the range 0.01-0.03 nm, with a noise of 0.01 nm, while with QCM, the resonance shift was 6-21 Hz, considering a noise of 1-2 Hz.

References

[1] Laich, F.; Fierro, F.; Martín, J.F. Applied and Environmental Microbiology. 2002, 68, 1211-9. doi: 10.1128/AEM.68.3.1211-1219.2002.

Acknowledgments

This work was funded under the European Union’s Horizon 2020 research and innovation program through the Marie Skłodowska-Curie grant agreement No. 101007299 (T.H.), the Science Agency VEGA, project No. 1/0445/23 (T.H.) and by DAAD PPP project (T.H. and W.F.).

The rapid detection and identification of harmful bacteria for food quality control, environmental pollution, medical diagnostics, and chemical and biological crises constitutes a crucial issue. Here, we demonstrate a strategy for sensing bacteria based on the surface-enhanced Raman scattering method. The procedure involves the synthesis of gold nanoparticles (AuNPs) via a simple chemical reduction method and subsequent studies on bacteria. The concentrated AuNPs, coupled with aluminum foil, form a SERS-active substrate and then the bacterial sample is placed on this substrate to identify the strain of bacteria present. After an interaction time of approx. 5 min, the substrate is put on the sample stage of a Raman spectroscope and a laser source of 785 nm is incident on it. The cell walls and intracellular components of the bacteria have consistent and distinctive characteristic bands which aid in the identification of the bacterial strains present in the sample. This substrate offers advantages such as a rapid acquisition time at an extremely low power, great sensitivity, and a simple operating technique that does not require any complex procedures or protocols to collect bacteria. The substrate shows an enhancement factor tothe order of 10⁷ and a limit of detection of 10^-7 M for Rhodamine 6G. The developed SERS-active substrate, with its low cost, reproducibility, and outstanding detection capability, has a wide range of applications, including food safety and tracking the environment.

Conventional disease detection methods in agriculture are constrained by the presence of personal opinions and the amount of work required, which hinder broad-scale disease monitoring. This study aims to overcome these difficulties by introducing a biosensor-assisted deep learning system that improves disease identification in precision agriculture. Biosensors, such as hyperspectral or electrochemical sensors, offer an initial means of collecting objective data, which complements subsequent analysis using deep learning techniques. The performance of popular deep learning models (VGG16, MobileNetV2, ResNet50) in classifying diseases across 15 categories is assessed via evaluation on the PlantVillage dataset. In addition, a new Convolutional Neural Network (CNN) structure, which achieves a higher accuracy (99.05%) compared to pre-existing models, is shown. Biosensor data serve as a first screening process, which has the ability to decrease the number of photos that need to undergo deep learning analysis. By utilising this integrated method, the precision and effectiveness of disease identification are enhanced. This framework allows for the early and accurate detection of diseases, which in turn allows for specific therapies and encourages the use of sustainable farming methods. The exceptional precision (99.05%) creates opportunities for practical implementation, perhaps reducing production losses and optimising resource allocation.

There is a growing interest in utilising diamond-related electrodes for biomedical applications, like cellular stimulation and tissue engineering, due to their exceptional biostability and long–term durability when implanted into living tissue. Here, we investigate the electrochemical performance and stability of laser-graphitised polycrystalline diamond (PCD) as an electrode and evaluate its biocompatibility with human mesenchymal stem cells (hMSCs). The PCD surface was graphitised using an ultraviolet (UV) nanosecond-pulsed laser under ambient atmosphere and temperature conditions. Microstructural changes were analysed before and after laser writing using scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrochemical performance and stability were evaluated through Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and multi-potential and multi-current steps over an extended period of time. To study the electrode’s biocompatibility, bone marrow hMSCs were cultured on the surface of the electrode and tissue culture plastic (TCP) as controls, followed by a resazurin assay at 24, 48, and 72 hours. The laser-graphitised electrode exhibited a high specific double-layer capacitance of 195 µF/cm² and a specific electrochemical impedance of 129 Ω·cm² at 1 kHz. The hMSCs cultured on the electrode showed over 80% viability relative to TCP, indicating the non-cytotoxicity and growth-promoting effect of hMSCs. Notably, the hMSCs cultured on the electrode were elongated after 3 days, aligning with the topography of the laser-graphitised PCD surface. The graphitisation of PCD through nanosecond laser writing presents promising electrochemical properties, indicating its suitability as both a recording electrode for biosensing and a stimulating electrode for cellular modulation. Furthermore, the laser-graphitised PCD demonstrated notable biocompatibility with hMSCs. These findings suggest its potential for various biomedical applications, including biosensing and stem cell therapeutics, through promoting the proliferation and guiding the differentiation of stem cells into specialised cell types.

Atenolol is a medication belonging to the class of drugs known as beta blockers, used to treat high blood pressure (hypertension) and irregular heartbeats (arrhythmia). Its presence in the environment has serious impact for human, animals and water ecosystem. In this context, the aim of this study was to develop a simple voltammetric method for the determination of atenolol (ATN) using a carbon-paste electrode modified with nanomaterials TiO₂ and GO/TiO_2. The analytical performance of the modified sensor was evaluated using square wave voltammetry and cyclic voltammetry in 0.1 mol L ⁻¹ acid sulfuric solution (H₂SO₄), pH 2. The nanocomposite electrode CPE/GO/TiO₂ exhibits excellent electrocatalytic activity towards ATN oxidations at 0.1 mol L ⁻¹ H₂SO₄ compared with unmodified carbon-paste electrodes CPE and electrodes modified with titanium oxide CPE/TiO₂. Different experimental and conditional parameters were optimized such as supporting electrolyte, pH, amplitude, frequency, etc. Under optimal conditions, linear calibration curves were obtained ranging from 1.7 to 23.2 µmol L ⁻¹ for ATN with detection limits of 0.05 μmol L ⁻¹, respectively. The modified nanocomposite CPE/ GO/ TiO₂ sensor showed good sensitivity and good repeatability (RSD ≤ 0.61%) for ATN determination. The proposed sensor is mechanically robust and presented reproducible results and a long-term useful life. In order to verify the usefulness of the developed method, the nanocomposite sensor CPE/GO/TiO_2, was applied to the detection of atenolol in a real sample (pharmaceutical tablets without any pre-treatment). Excipients present in the tablets did not interfere with the assay. Recoveries ranging from 97.7% to 106 % were obtained. The results proved that the CPE/ GO/ TiO₂ voltammetric sensor might be successfully applied in the routine quality control of ATN in complex matrices.

Laser-induced graphene (LIG) sensors are becoming popular in various agricultural applications due to their ease of fabrication and superior characteristics. These LIG sensors can be used for real-time nutrient monitoring. By using a one-step laser engraving process, it is possible to create flexible graphene electronics on polyimide substrates. A CO2 laser was used for engraving purpose as it changes sp3-hybridized carbon which is present in substrates like polyimide into sp2-hybridized carbon. Selective patterns of polyimide film (Kapton tape) can be converted into sp2-hybridized carbon using laser beam. A 30W CO2 laser was used to engrave the LIG sensor on polyamide sheet with optimized settings i.e. 11% power and 1.2 % speed. Distinct ionophores specific to NH4+ (nonactin) or NO3− (tridodecylmethylammonium nitrate) were functionalized within poly (vinyl chloride)-based membranes to create distinct solid contact ion-selective electrodes (SC-ISEs) for NH4 + and NO3− ion sensing cocktails by drop casting on working electrode, respectively. An Ag/AgCl electrode printed with Ag/AgCl ink operated as the reference electrode, while the LIG electrode worked as the working and counter electrode. The electrochemical ion-selective detection of plant accessible nitrogen (i.e., including ammonium and nitrate ions: NH4 + and NO3-) in soil samples was conducted using these LIG sensors. Using a three-electrode setup, Cyclic Voltammetry (CV) scans were performed to determine the various concentrations of ammonium and nitrate in soil samples.

The ability to control and understand the temperature at the nanoscale is fundamental for manipulating physical, chemical, and biological processes.

Nanothermometry is a crucial aspect of scientific and technological applications ranging from electronics to biological systems. The development of well-defined protocols for precise temperature determination is essential for advancing research and applications in nanotechnology. Accurate nanoscale temperature measurements involve the integration of various strategies, including the design and fabrication of new materials, the implementation of detection techniques, and the testing of prototypes for real-world applications.

The utilization of optical techniques, such as fluorescence and Raman spectroscopy, enables the efficient characterization of different materials. The ability to synthesize and test materials using these techniques allows researchers to identify the most suitable and sensitive nanothermometry materials. This is particularly important when prototype devices are developed for biomedical applications, where biocompatibility and non-invasiveness are essential.

This presentation will focus on Raman and luminescent nanostructures. The Raman active material is TiO₂, anatase, while lanthanides, such as Yb³⁺ and Er³⁺, are used as luminescent materials; they are both characterized by a signal strongly dependent on the local temperature.

Anatase nanoparticles are synthetized by MW-assisted (MW) and solvothermal procedures, while core@shell nanoparticles are realized by MW-assisted co-precipitation of CaCl3, YbCl3, and ErCl3 and sol–gel methods. Fluorescence and Raman measurements were conducted on sample powders in the visible and n-IR ranges. The sample, maintained at a defined temperature via a temperature controller, underwent laser beam focalization through a microscope. The signals were then collected through a triple monochromator and a liquidnitrogen-cooled CCD camera. Preliminary findings indicate the feasibility of obtaining reliable temperatures for characterizing the local temperature using fluorescence and Raman techniques.

The preliminary results indicate a reliable and accurate temperature characterization, paving the way for further advances in nanothermometry and its applications in diverse fields, including biomedicine.

Introduction: We describe the first DNA biosensors for the identification of the cultural variety of olive oil, which is an important agricultural product. Because the varietal origin affects the quality characteristics, monovarietal olive oils with protected designation of origin are the focus of consumers and producers. Contrary to other tedious and costly methods, such as real-time PCR with fluorometric detection and capillary electrophoresis, the proposed biosensors enable visual detection by the naked eye without sophisticated instrumentation. Also, the proposed method is based on unique DNA markers rather than small metabolites and is therefore not affected by environmental/climatic changes, geographic origin, soil composition, harvesting period and storage conditions.

Methods: We performed simultaneous genotyping of four single-nucleotide polymorphisms corresponding to eight alleles. The steps are DNA extraction, quadruplex PCR of cycloartenol synthase and lupeol synthase, octaplex genotyping by DNA polymerase (20 min) and application to the biosensor without prior purification. The biosensor is immersed in developing buffer and the detection requires 20 min.

Results: A red spot appears when an allele is present. The combination of red spots from eight alleles provides the genetic identity. The biosensors were applied, accurately and reproducibly, to the identification of seven olive varieties using DNA isolated from leaves and olive oil. The results were in full concordance with sequencing data. As low as 5 ng of extracted olive oil DNA can be used for PCR. The CVs were in the range of 0.5–9%.

Conclusions: Because of their simplicity and practicality, we anticipate that the proposed biosensors will find wide applicability in determining the authentication and traceability of olive oil.

Acknowledgements: This research has been co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program ‘Competitiveness, Entrepreneurship and Innovation’, under the call ‘RESEARCH – CREATE – INNOVATE (project code: T2EDK-02637)’.