Yizhen Wan

Inspired by the efficient mass transfer properties of biological vascular systems, tubular structures have garnered significant attention in sensing due to their outstanding hydrodynamic performance. Transforming these passive conduits into active sensing platforms requires the in-situ integration of high-performance signal transduction platforms. This work reports an optical interferometry platform based on a tubular SiO2−TiO2 hybrid inverse opal (IO) structure for label-free, real-time biosensing. By employing a sol−gel co-growth, the hybrid IO films are synthesized directly on tube inner walls, combining silica’s robustness with titania’s high refractive index to ensure stable, high-fidelity Fabry−Pérot signals. Through the experiment of refractive index corresponding to salt concentration gradient demonstrates that the high porosity (74%) of the IO structure effectively eliminates steric hindrance for macromolecular diffusion, achieving a six-fold increase in optical sensitivity compared to traditional silica colloidal crystal structures. At the hydrodynamic level, the macroscopic tubular configuration promotes convective transport, ensuring rapid response kinetics even under high flow rates. Furthermore, by functionalizing the luminal wall, the platform enables the specific quantitative detection of IgG in diluted whole blood. This optical interferometry platform, which integrates periodic porous structures with biomimetic fluidic interfaces, offers a pathway for developing next-generation biosensing.

Assessment of the global fibrinolytic capacity of whole blood is of great clinical value for the diagnosis of bleeding and thrombotic disorders, the guidance of therapeutic decision-making, and prognosis monitoring. However, due to the complexity of the fibrinolytic system, existing fibrinolysis assays fail to meet clinical diagnostic requirements, and it remains challenging to design a “gold standard” analytical method that can reflect the global fibrinolysis level of blood. Here, we constructed a fibrin clot exhibiting optical interference effects as a fibrinolysis model, and introduced an ordered porous layer interferometry (OPLI) technique for real-time, in situ monitoring of the global fibrinolytic capacity of whole blood. We equated the global fibrinolytic capacity to plasmin activity while effectively suppressing non-specific adsorption under dynamic blood-flow conditions, thereby enabling accurate quantitative evaluation. The developed method was applied to monitor the dose-dependent downregulating effects of the endogenous fibrinolytic inhibitors PAI-1 and α2-AP on whole blood global fibrinolytic activity. Furthermore, this method successfully differentiated and quantified the ranges of global fibrinolytic capacity among hypofibrinolysis, normal fibrinolysis, and hyperfibrinolysis phenotypes. The analytical results showed a strong correlation with corresponding clinical bleeding and thrombosis risk scores. A parallel comparison with the thromboelastography method further validated the clinical applicability of this method.

The fibrinolytic system serves as the core mechanism for maintaining vascular patency and cardiovascular homeostasis, and precise, rapid fibrinolysis analysis is crucial for the clinical prediction of thrombosis or bleeding. In this study, the fibrin-loaded fibrinolytic responsive interference layer was constructed using tubular SiO2–TiO2 hybrid inverse opal (IO) as the scaffold and was combined with ordered porous layer interferometry (OPLI) technology for real-time and rapid fibrinolysis analysis. The tubular IO prepared by the sol–gel co-growth method can load more fibrin and endow them with optical interference effects. The fibrinolysis triggered by the model enzyme nattokinase leads to the migration of the interference fringes of the interference layer, which could be reflected by optical thickness changes (ΔOT) tracked in real-time by the OPLI system. Compared with the silica colloidal crystal film with opal structure, the tubular SiO2–TiO2 hybrid IO exhibited higher sensitivity and shorter detection times in fibrinolysis analysis. Furthermore, the introduction of lysine into the fibrinolytic responsive interference layer can further shorten the detection time of fibrinolytic activity of nattokinase to 10 min. Importantly, both the fibrinolytic interference sensing models with and without lysine adsorption demonstrated high reliability in fibrinolysis analysis of nattokinase-spiked whole blood samples. A parallel comparison with the thromboelastography method further validated the accuracy of this method.

Real-time monitoring of interfacial lipolysis is critical for understanding lipid metabolism and food digestion but remains challenging for traditional analytical techniques due to the complexity of heterogeneous lipid-aqueous interfaces. Here, a label-free optical interferometric method based on three-dimensional ordered polystyrene inverse opal (PS-IO) films for the dynamic analysis of lipolysis was reported. The PS-IO films, featuring higher porosity and hydrophobicity, serve as a high-specific-surface-area host for triglyceride immobilization, forming a sensitive optical layer for interferometric biosensing. As lipase enters the layer and hydrolyzes lipids, the mass fluctuation induces a shift in Fabry-Pérot fringes, which was captured and converted to a change in optical thickness by self-developed ordered porous layer interferometry (OPLI). Using an optimized lipolysis model, the analytical system exhibited a linear response to lipase concentrations ranging from 1 to 200 U/L. Furthermore, the high temporal resolution of the system enabled the derivation of Michaelis-Menten kinetic parameters. The optical interferometry platform was successfully applied to discriminate the digestion of triglycerides with varying degrees of unsaturation and commercial edible oils, revealing that unsaturation correlates with lipolysis rates due to the steric structure of lipid molecules at the interface. This methodology provides an effective and quantitative tool for probing the lipolysis of triglycerides with different unsaturation and evaluating the digestion behavior of edible oil in the food industry and physiological systems.

The assessment of lactoferrin (LF) bioactivity is pivotal for determining the nutritional quality and processing history of dairy products; however, current detection methods cannot effectively distinguish between active and thermally denatured forms. Herein, a competitive lateral flow assay (LFA) based on specific electrostatic binding was developed using fondaparinux, a synthetic heparin-like pentasaccharide, as a nonantibody recognition element. To address immobilization challenges, a "BSA-bridging" strategy was employed to construct stable AuNPs-BSA-fondaparinux nanoprobes. Under optimized conditions, the LFA achieved quantitative LF detection within 15 min (LOD 0.94 μg/mL; linear range: 1-200 μg/mL; R² = 0.973) with high specificity. Comparisons with high-performance liquid chromatography confirmed the good accuracy of the proposed method. Furthermore, the assay selectively detected the loss of bioactive LF due to thermal denaturation in pasteurized milk. Overall, this work establishes a rapid platform utilizing a synthetic receptor for monitoring lactoferrin bioactivity changes during thermal processing in the dairy industry.

The cell surface glycocalyx is a complex and dynamic network of glycoproteins and proteoglycans that plays a pivotal role in life activities. Its three-dimensional architecture is composed of various glycosaminoglycans (GAGs) mediating various biological functions. Exploring the structure of GAGs and its interaction with proteins or the GAGs code is of great significance for revealing the molecular mechanisms of biological processes. However, the structural complexity of the glycocalyx at both cellular and tissue scales poses challenges for accurate representation, while conventional planar sensors inadequately capture its multiscale spatial characteristics, thereby limiting precise analysis of dynamic GAG-protein interactions. In this study, a three-dimensional ordered interference substrate with surface-modified heparin was constructed to simulate the fine topological structure of the glycocalyx. On this ordered porous layer interferometry (OPLI) platform, combined with experimental and computer simulation methods, the effects of heparin density, spatial distribution, and chain length on the binding behavior of SARS-CoV-2 spike protein were systematically investigated. The experimental results show that a medium heparin density can maximize the binding strength of the spike protein. The affinity of heparin for spike protein can be enhanced by increasing the density of the three-dimensional spatial distribution. Molecular docking and thermodynamic experiments suggest that hydrogen bonds rather than electrostatic interactions play a crucial role in the binding strength. This study recreates the glycocalyx microenvironment, providing a highly biomimetic platform that not only deepens the molecular understanding of viral infection but also lays a methodological foundation for GAG code analysis and drug development.

In this work, we fabricated uniformly ordered SiO₂-TiO₂ hybrid inverse opal Fabry-Pérot layers based on sol-gel cogrowth strategy and utilized their unique Fabry-Pérot fringes for real-time and dynamic monitoring of lipid degradation processes. By optimizing the concentrations of polystyrene nanospheres, we achieved precise modulation of film thickness, ranging from nanometers to micrometers. The homogeneous SiO₂-TiO₂ hybrid system is formed through the combination of titanium(IV) bis (ammonium lactato) dihydroxide solution and tetraethyl orthosilicate precursors, allowing refractive index (RI) tailoring via SiO₂-TiO₂ ratio regulation. Evaluation using ordered porous layer interferometry (OPLI) platform confirms the optimized films exhibit both high optical interference contrast and RI sensitivity. Building upon this foundation, a lipid interferometric layer is constructed within the inverse opal film and integrated with OPLI system to create a biosensing platform. This system enables real-time monitoring of lipid and lipase digestion processes, with changes in effective optical thickness are calculated from Fabry-Pérot fringe pattern shifts induced by RI variations during digestion. The biosensor demonstrates excellent sensitivity and a wide linear range (5-2000 U/L) for real-time process monitoring, offering new possibilities for studying liquid-phase biomolecular interactions. This integrated platform shows significant potential for applications in clinical diagnostics and pharmaceutical research.

Accurate in vitro lumen models are critical for simulating physiological microenvironments, as numerous biological processes are intrinsically linked to lumen structure. However, current models are difficult to simulate the curvature-dependent biomechanics and dynamic flow conditions of luminal systems, limiting their utility in complex biological matrices. In this study, tubular colloidal crystal films are prepared by combining biomimetic microstructures with photonic crystal technology and utilized its unique interference effect to achieve dynamic monitoring of biomolecular interactions. The interference effects are observed in highly ordered and structurally uniform tubular films prepared based on solvent evaporation-induced self-assembly. By adjusting the inner diameter of the glass tube and the concentration of the colloidal suspension and simultaneously measuring the optical thickness and refractive index response of the film to ethanol gradients, the curvature tunability, structural stability, and functional feasibility of the tubular films were evaluated. Furthermore, Staphylococcus aureus protein A (SPA)-functionalized tubular films combined with an ordered porous layer interferometry system enable in situ real-time monitoring of human immunoglobulin G binding and release from SPA-modified materials, validating the platform's feasibility. This strategy of integrating curvature bionic design with photonic crystal technology provides a dynamic biomimicry, real-time response, and visualization analysis platform for studying physiological microenvironments.

Lactoferrin (LF) is a bioactive molecule that plays a pivotal role in innate immunity and is widely present in dairy products. It has been demonstrated to restrict viral infections by blocking binding sites on heparan sulfate (HS). However, existing analytical methods primarily focus on the LF content rather than its bioactivity, highlighting the need for a dedicated approach to antiviral LF analysis. Developing an appropriate tool for antiviral LF analysis in dairy products is crucial for consumer welfare and product quality control, as the daily intake of LF-rich products offers significant health benefits. However, in one of the primary LF-rich dietary sources, bovine milk, the main limitation of current analysis methods is the lack of an efficient receptor for characterizing antiviral LF. In this study, we developed fondaparinux as a promising receptor for antiviral LF analysis and introduced ordered porous layer interferometry (OPLI) for real-time, in situ monitoring of antiviral LF. Furthermore, we compared the proposed method with the enzyme-linked immunosorbent assay (ELISA) and evaluated antiviral LF content across different milk samples.

The protein carrier and encapsulation system based on polyelectrolytes plays crucial roles in drug research and development. Traditional methods such as isothermal titration calorimetry and molecular dynamics simulation have illuminated parts of this complex relationship. However, they fall short of capturing the full picture of the interaction during the carrier's fabrication and protein loading dynamics. We propose a strategy in this article that combines ordered porous layer interferometry (OPLI) with electrophoretic light scattering (ELS) to study this interaction, effectively investigating the mechanism of polyelectrolyte-protein interaction and verifying it through charge measurement. The layer-by-layer assembly method was used to fabricate the polyelectrolyte complex (PEC) layer on both silica colloidal crystal (SCC) films and silica nanospheres. OPLI with the SCC film as the substrate was employed to investigate real-time interaction between PEC and proteins, while ELS determined the ζ-potential of the PEC layer and proteins to illustrate the interaction mechanism further. It was found that surface charge affects electrostatic adsorption at different pH values and numbers of polyelectrolyte layers. As the ζ-potential difference increased, protein adsorption on the PEC layer also increased significantly. Adjusting the pH value during protein loading can maximize the loading efficiency. In our strategy, we can transfer the in situ interface study of OPLI into a dispersed nanosphere system directly because the silica nanosphere can be the building block of the OPLI substrate while being the solid supporter for polyelectrolyte carriers. By combining OPLI and ELS, this work provides an efficient strategy for developing protein drug carriers based on polyelectrolytes.