This work concentrates on the design and implementation of aptamer-based electrochemical biosensors using a layer-by-layer approach for precise tracking of mucin-1 (MUC1), an important biomarker linked to breast cancer. The electrochemical biosensor was created by modifying a screen-printed carbon electrode (SPCE) with V2C MXene booster and gold nanoparticles (Au-NPs), along with Cd2+ integrated aptamer (AP) (SPCE/V2C-MXene/Au NPs/Cd2+-AP). This biosensor demonstrated high specificity and affinity for MUC1, establishing a sensitive quantification mechanism. The MXene nanolayer was produced and analyzed via TEM, XPS, SEM, AFM, BET, and MAP techniques. It served as a supportive material that enhanced electrochemical conductivity and allowed for the integration of the aptamer (AP) as the biological recognition component. The biosensor was constructed by immobilizing MUC1-specific aptamers onto the surfaces of SPCE/V2C-MXene/Au NPs, enabling selective recognition and binding with MUC1. The recorded signal, corresponding to Cd2+ integrated with AP at SPCE/V2C-MXene/Au NPs/Cd2+-AP, enabled quantitative assessment of MUC1 levels. The findings showed a linear concentration span of 1.0–500 pg/mL for detecting MUC1, achieving a detection limit of 3.45 fg/mL utilizing the SPCE/ V2C-MXene/Au NPs/Cd2+-AP biosensor. The SPCE/V2C-MXene/Au NPs/Cd2+-AP biosensor exhibited a good affinity for the detection of MUC1 in the presence of other breast cancer biomarkers, confirming its selectivity.

In the current research, a manganese and cobalt oxides-based nanocatalyst was developed which was used to make an efficient cathode electrode for fuel cells. The nano MnOx/ MnCo2O4 was synthesized through a hydrothermal procedure followed by sintering at 500–600 °C. X-ray diffraction and scanning electron microscopy besides electrochemical techniques were applied for the characterization of the synthesized nanocatalyst. The carbon black type Vulcan (XC-72R) and PTFE were used to prepare the active reaction material of the cathode electrode named carbon paste (CP). Loading of the synthesized nano MnOx/ MnCo2O4 on CP was optimized in a weight ratio of 10–90% for the oxygen reduction process in neutral conditions. The best performance was gained for the 50 W% MnOx/ MnCo2O4 loaded CP, whose active surface area was twice the bare CP. The values of the exchange current density of the ORR obtained by electrode containing 50 W% MnOx/ MnCo2O4 was calculated as 0.12 mA/cm2. The low price, good catalytic efficiency, and cyclic stability of the MnOx/ MnCo2O4 nanocatalyst compared to the commercial platinum-based catalysts confirm its ability to develop fuel cell electrodes.