Herein, dendrimer-modified montmorillonite (Mt)-decorated poly-Ɛ-caprolactone (PCL) and chitosan (CHIT)-based nanofibers were prepared. Mt was modified with a poly(amidoamine) generation 1 (PAMAM_G1) dendrimer, and the obtained PAMAM_G1–Mt was incorporated into the PCL–CHIT nanofiber’s structure. The PCL–CHIT/PAMAM_G1–Mt nanofibers were conjugated with glutamate oxidase (GluOx) to design a bio-based detection system for monosodium glutamate (MSG). PAMAM_G1–Mt was added to the PCL–CHIT backbone to provide a multipoint binding side to immobilize GluOx via covalent bonds. After the characterization of PCL–CHIT/PAMAM_G1–Mt/GluOx, it was calibrated for MSG. The linear ranges were determined from 0.025 to 0.25 mM MSG using PCL–CHIT/Mt/GluOx and from 0.0025 to 0.175 mM MSG using PCL–CHIT/PAMAMG₁–Mt/GluOx (with a detection limit of 7.019 µM for PCL–CHIT/Mt/GluOx and 1.045 µM for PCL–CHIT/PAMAMG₁–Mt/GluOx). Finally, PCL–CHIT/PAMAMG₁–Mt/GluOx was applied to analyze MSG content in tomato soup without interfering with the sample matrix, giving a recovery percentage of 103.125%. Hence, the nanofiber modification with dendrimer-intercalated Mt and GluOx conjugation onto the formed nanocomposite structures was performed, and the PCL–CHIT/PAMAM_G1–Mt/GluOx system was successfully developed for MSG detection.

We report here the electrochemical co-polymerization of two functional monomers, one containing fluorescent rhodamine dye (RF) and the other monomer having amine groups (RD), onto electroactive Indium Tin Oxide (ITO) glass. After one step preparation of these surfaces, a three peptide called ArginylGlysylAspartic acid (RGD) was immobilized via EDC chemistry by using amine groups (P(RF-co-RD)/RGD) of the co-polymer, for further use in various bio-applications such as cell adhesion and imaging as well as electrochemical cell sensing. The resultant RGD bound and also fluorescent platforms were utilized as targeted adhesion materials towards integrin avb3 receptor positive (U87-MG) cells and the selectivity was checked by using HaCaT cells as a control. Finally, electrochemical measurements were carried out to characterize step by step surface modification and detection of cell attachment. As a result, P(RF-co-RD)/RGD is a promising material for multi-purpose uses, such as fluorescence imaging without the need for an additional dye for cell visualization and as a targeted adhesion and electrochemical cell sensing platform.

Serum amyloid (SAA), one of the acute-phase reactants, plays a significant role in acute and chronic inflammatory diseases. It is widely used in the clinical field as a biomarker of inflammation. Developing rapid and sensitive measurement systems is crucial to precisely detect the presence of SAA, even at very low levels. Therefore, in this study, we developed an electrochemical immunosensor using electrospun nanofibers (ESNFs) based on poly-ε-caprolactone (PCL) and poly-l-Lysine (PLL) as an immobilization matrix. ESNFs covered the surfaces of screen-printed carbon electrodes (SPCEs) for enhanced performance. The PCL/PLL ESNFs were characterized using water contact angle measurements, scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy techniques. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and impedance spectroscopy (EIS) were employed to characterize the electrochemical behavior of the developed electrode surface. In conjunction with the analytical characterizations of the proposed immunosensor, linear range, limit of detection (LOD), interfering effect of some potential chemicals, and real sample applications were carried out. The sensor exhibited a working range and the linear range of 0.1–50 and 0.1–10 ng/mL with a calculated LOD of 0.061 ng/mL for SAA, respectively. Additionally, the sensor demonstrated advanced specificity, showing no response to the interfering species such as urea, glucose, insulin, and C-reactive protein. Validation of the sensor yielded excellent recovery for the artificial serum (100.04%), human real serum (103.32%), and artificial saliva (99.5%) samples containing 1 ng/mL SAA. Therefore, we believe that the sensor, with its high specificity, and sensitivity, can effectively contribute to the detection of SAA at low levels in biological fluids during clinical tests.

Vascular endothelial growth factor (VEGF) is an indispensable element in many physiological processes, while alterations in its level in the circulating system are signs of pathology-associated diseases. Therefore, its precise and selective detection is critical for clinical applications to monitor the progression of the pathology. In this study, an optical immunoassay biosensor was developed as a model study for detecting recombinant VEGF₁₆₅. The VEGF₁₆₅ sample was purified from recombinant Kluyveromyces lactis GG799 yeast cells. Indirect ELISA was used during the detection, wherein iron oxide nanoparticles (FeNPs) were utilized to obtain optical signals. The FeNPs were synthesized in the presence of lactose p-amino benzoic acid (LpAB). VEGF₁₆₅ antibody was conjugated to the LpAB-FeNPs through EDC/NHS chemistry to convert the iron oxide nanoparticles into VEGF₁₆₅ specific probes. The specificity of the prepared system was tested in the presence of potential serum-based interferents (i.e., glucose, urea, insulin, C-reactive protein, and serum amyloid A), and validation studies were performed in a simulated serum sample. The proposed immunoassay showed a wide detection range (0.5 to 100 ng/mL) with a detection limit of 0.29 ng/mL. These results show that the developed assay could offer a sensitive, simple, specific, reliable, and high-throughput detection platform that can be used in the clinical diagnostics of VEGF. Graphical Abstract