E. coli O157:H7, one of the major foodborne pathogens, can cause a significant threat to the safety of foods. The aim of this research is to develop an activated biochar-based immunosensor that can rapidly detect E. coli O157:H7 cells without incubation in pure culture. Biochar was developed from corn stalks using proprietary reactors and then activated using steam-activation treatment. The developed activated biochar presented an enhanced surface area of 830.78 m²/g. To develop the biosensor, the gold electrode of the sensor was first coated with activated biochar and then functionalized with streptavidin as a linker and further immobilized with biotin-labeled anti-E. coli polyclonal antibodies (pAbs). The optimum concentration of activated biochar for sensor development was determined to be 20 mg/mL. Binding of anti-E. coli pAbs with E. coli O157:H7 resulted in a significant increase in impedance amplitude from 3.5 to 8.5 kΩ when compared to an only activated biochar-coated electrode. The developed immunosensor was able to detect E. coli O157:H7 cells with a limit of detection of 4 log CFU/mL without incubation. Successful binding of E. coli O157:H7 onto an activated biochar-based immunosensor was observed on the microelectrode surface in scanning electron microscopy (SEM) images.

Bio-based epoxy resin materials have obtained significant attention in the packaging industry due to concerns about the environmental and economic impacts of traditional petroleum-based plastics. The aim of this research is to improve bio-based resins’ properties by investigating varying formic acid contents in the presence of a green catalyst and characterizing their physical, chemical, and mechanical properties for further scaled-up bio-based resin production for industrial packaging applications. The crude soybean oil was epoxidized with formic acid as an oxidizing agent at varying equivalent weights of 10:1 to 10:10 of soybean oil: formic acid in the presence of hydrogen peroxide and choline chloride-oxalic acid as a bi-functional green catalyst. The effect of increasing the amount of formic acid used to epoxidize crude soybean oil was evaluated with infrared (IR) spectroscopy, rheological, and epoxy yield measurements. The results demonstrated that formic acid significantly influenced the epoxidation of soybean oil, leading to a higher conversion of carbon-carbon double bonds, with a selectivity of 98% when the ratio of soybean oil to formic acid was between 10:5 and 10:10. The bio-resin film was formulated using the improved epoxidized soybean oils—from ESO (10:2.5) to ESO (10:10)—and equal amounts of acrylic acid. The results showed that resin films led to an improvement in tensile strength (ca. 180 MPa) and thermal stability at 360 °C. Although further research is necessary, this study provides valuable insights for designing an effective epoxidation process for renewable sources and developing bio-resin materials for future packaging applications.

The evolution of high-performance electrode materials has significantly impacted the development of real-time monitoring biosensors, emphasizing the need for compatibility with biomaterials and robust electrochemical properties. This work focuses on creating electrode materials utilizing single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), specifically examining their dispersion behavior and electrochemical characteristics. By using ultrasonic waves, we analyzed the dispersion of CNTs in various solvents, including N, N-dimethylformamide (DMF), deionized water (DW), ethanol, and acetone. The findings revealed that SWCNTs achieved optimal dispersion without precipitation in DMF. Additionally, we observed that the electrical resistance decreased as the concentration of SWCNTs increased from 0.025 to 0.4 g/L, with significant conductivity enhancements noted between 0.2 g/L and 0.4 g/L in DMF. In constructing the biosensor platform, we employed 1-pyrenebutanoic acid succinimidyl ester (PBSE) as a linker molecule, while glucose oxidase (Gox) served as the binding substrate. The interaction between Gox and glucose led to a notable decrease in the biosensor’s resistance values as glucose concentrations ranged from 0.001 to 0.1 M. These results provide foundational insights into the development of SWCNT-based electrode materials and suggest a promising pathway toward the next generation of efficient and reliable biosensors.

The development of eco-friendly, mechanically stable, and biocompatible materials for medical packaging has gained significant attention in recent years. Halloysite nanotubes (HNTs) have emerged as a promising nanomaterial due to their unique tubular structure, high aspect ratio, and biocompatibility. We aim to develop a novel soybean oil-based thermoset bio-resin incorporating HNTs and to characterize its physical and functional properties for medical packaging. Soybean oil was epoxidized using an eco-friendly method and used as a precursor for preparing the thermoset resin (ESOR). Different amounts of HNTs (0.25, 0.50, and 1.0 wt.%) were used to prepare the ESOR/HNTs blends. Various characteristics such as transparency, tensile strength, thermal resistance, and water absorption were investigated. While incorporating HNTs improved the tensile strength and thermal properties of the ESOR, it noticeably reduced its transparency at the 1.0 wt.% level. Therefore, HNTs were modified using sodium hydroxide and (3-Aminopropyl) triethoxysilane (APTES) and ESOR/HNTs blends were made using 1.0 wt.% of modified HNTs. It was shown that modifying HNTs using NaOH improved the transparency and mechanical properties of prepared blends compared to those with the same amount of unmodified HNTs. However, modifying using (3-Aminopropyl) triethoxysilane (APTES) decreased the transparency but improved the water absorption of prepared resins. This study provides valuable insights into the design of HNT-based ESOR blends as a sustainable material for medical packaging, contributing to the advancement of eco-friendly packaging solutions in the healthcare industry.