The requirement to prevent foodborne illnesses underscores the need for reliable detection tools, stimulating biosensor technology with practical solutions for in-field applications. This study introduces a low-cost immunosensor based on a single-walled carbon nanotube (SWCNT)-modified gold leaf electrode (GLE) for the sensitive detection of Escherichia coli. The immunosensor is realized with a layer-by-layer (LbL) assembly technique, creating an electrostatic bond between positively charged polyethylenimine (PEI) and negatively charged carboxyl-functionalized SWCNTs on the GLE. The structural and functional characterization of the PEI-SWCNT film was performed with Raman spectroscopy, high-resolution scanning electron microscopy (HRSEM), and electrical measurements. The PEI-SWCNT film was used as a substrate for antibody immobilization, and the electrochemical sensing potential was validated using electrochemical impedance spectroscopy (EIS). The results showed a wide dynamic range of E. coli detection, 10¹-10⁸ cfu/mL, with a limit of detection (LOD) of 1.6 cfu/mL in buffer and 15 cfu/mL in the aqueous solution used for cleansing fresh lettuce leaves, affirming its efficiency as a practical and affordable tool in enhancing food safety.

Single-walled carbon nanotubes (SWCNTs) are well-known for their excellent electrical conductivity. One promising application for SWCNT-based thin films is as transparent electrodes for uncooled mid-IR detectors (MIR). In this paper, a combination of computational and experimental studies were performed to understand the chemistry behind the stability of carboxylic SWCNTs (SWCNTs-COOH) dispersions in different solvents. A computational study based on the density functional tight-binding (DFTB) method was applied to understand the interactions of COOH-functionalized carbon nanotubes with selected solvents. Attention was focused on understanding how the protonation of COOH groups influences the binding energies between SWCNTs and different solvents. Thin film electrodes were prepared by alternately depositing PEI and SWCNT-COOH on soda lime glass substrates. To prepare a stable SWCNT dispersion, different solvents were tested, such as deionized (DI) water, ethanol and acetone. The SWCNT-COOH dispersion stability was tested in different solvents. Samples were prepared to study the relationship between the number of depositions, transparency in the MIR range (2.5–5 µm) and conductivity, looking for the optimal thickness that would satisfy the application. The MIR transparency of the electrode was reduced by 20% for the thickest SWCNT layers, whereas sheet resistance values were reduced to 150–200 kΩ/sq.

Epitaxial La1-xSrxMnO3 (LSMO, where x = 0, 0.1, 0.3 and 0.5) films on single crystal SrTiO3 (001) substrate were obtained by water-based chemical solution deposition method, so-called polymer assisted deposition (PAD). The as-prepared films (heated at 750?C for 1 h) have thicknesses of ?30 nm, high uniformity, clear and well-defined interface and crack-free surfaces. In addition, they are characterized by the formation of an imperfect crystal structure with some disoriented areas, small amount of non-stoichiometric phase and defects created just to support the epitaxial film growth. During multiple annealing at different temperatures up to 900?C epitaxial nature was preserved in all LSMO films. The structure rearrangement through elimination of defects and formation of unit cell closer to the corresponding bulk stoichiometric phase were observed. The magnetic properties of the LSMO thin films were measured using SQUID magnetometer in the temperature range of 5-400K with the field applied parallel (in-plane) and perpendicular (out-of-plane) to the film surface. The angle dependence of the magnetic moment in the LSMO thin films at the room temperature was also measured by a vibrating sample magnetometer.