Dongguan University of Technology

Biosensing performance is often compromised by antibody activity loss caused by random immobilization, which remains a critical challenge in immunoassay development. Conventional trial-and-error strategies for interface design lack mechanistic insight, limiting the optimization of antibody orientation and function. Here, we address this gap by establishing a molecular simulation-driven rational design paradigm to construct optimal antibody-oriented interfaces for enhanced biosensing performance.

Molecular dynamics simulations revealed that the HWRGWVC heptapeptide mediates directional antibody immobilization via synergistic electrostatic pre-orientation (Arg/His residues) and hydrophobic interactions (Trp), with a binding energy of -41.17 kcal/mol. Guided by this mechanism, we developed an icELISA for zearalenone detection. Compared to random immobilization, the oriented approach increased antibody coupling efficiency to 84.3%, Fab exposure rate to 60.9 %, and affinity to 3.86 × 10⁸ M^-1, while reducing antibody consumption by 50 %. The assay achieved a detection limit of 0.006 μg/kg in grains (100-fold more sensitive than conventional ELISA), with recoveries of 91.1-101.9 %, CVs of 3.7-9.2 %, and stability over 150 days. Results from 10 natural samples correlated strongly with LC-MS/MS (R² > 0.95).

This work delivers a highly sensitive, simulation-informed platform for mycotoxin detection in grains, while establishing a generalizable framework for rational design of next-generation immunoassays. By overcoming antibody activity loss via oriented immobilization, the strategy enhances assay performance and reduces reagent consumption, offering broad utility in biosensing and food safety applications.

In recent years, sodium caseinate-stabilized solid lipid particles (NaCas-SLPs) have shown potential in stabilizing Pickering emulsions, yet the impact of salts on their freeze-thaw stability remains debated. This study elucidates how NaCl modulates the interfacial assembly and crystallization behavior of NaCas-SLPs, and consequently reshapes the freeze-thaw stability and rheological performance of the resulting Pickering emulsions. The results demonstrated that NaCl regulated particle size, ζ-potential, and contact angle, thereby affecting interfacial protein adsorption and fat crystallization behaviors. These changes enabled SLP rearrangement at the oil-water interface and the formation of a more compact and stable interfacial structure. In addition, closely packed droplets and inter-droplet crystal bridging contributed to a dual stabilization mechanism. DSC and XRD analyses confirmed that NaCl effectively restricted lipid molecular migration and rearrangement during freeze-thaw cycling, facilitating the transformation toward more thermodynamically stable β crystals. Meanwhile, the strengthened interfacial layer and crystal network enhanced viscoelasticity and improved resistance to droplet aggregation and coalescence. These findings provide fundamental insight into ion-mediated stabilization mechanisms and highlight the potential of NaCas-SLPs for developing freeze-thaw resistant food emulsions.

Developing cost-effective proton exchange membrane fuel cells (PEMFCs) is imperative yet challenging with respect to the performance of Pt-based membrane electrode assembly (MEA) when using an ultralow Pt loading. Here, we report a hybrid fuel cell catalyst comprising a Pt-skin Pt₃Mn intermetallic on a manganese-nitrogen-carbon (Mn-N-C) support. The successful synthesis of this hybrid catalyst relies on the rational use of metal phthalocyanine molecules that serve as a chemical source for the synthesis of Pt₃Mn and the construction of Mn-N-C. Pt₃Mn/Mn-N-C demonstrates high mass activity (1.22 A mg_Pt^-1) with an ultralow Pt loading of 0.025 mg_Pt cm^-2 and retains 76.3% of its mass activity after 30000-cycle accelerated stress tests (ASTs). Mechanistic investigations and theoretical calculations imply that the synergistic contribution of Mn-N-C networks and structurally stable Pt-skin Pt₃Mn hybrid catalysts with enhanced Mn specific anchoring is responsible for achieving high activity and durability in fuel cells.