“Unique Dual-Affinity Strategy for Specific Lipopolysaccharide Clearance in Sepsis Therapy: Peptide-Conjugated Molecularly Imprinted Polymers via Emulsion Interfacial Polymerization”

Today we share important research published in Advanced Materialsby the team of Guangyan Qing from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Addressing the global challenge of specifically clearing blood endotoxin (LPS) in sepsis therapy, this study pioneeringly proposes a dual-affinity strategy. By screening high-affinity targeting peptides via phage display and constructing molecularly imprinted polymers with geometrically matched cavities through emulsion interfacial polymerization, followed by their conjugation, the work successfully creates an LPS adsorbent exhibiting high specificity, high adsorption capacity, and excellent biocompatibility, demonstrating outstanding therapeutic potential in septic animal models.

01 Research Background

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, affecting tens of millions globally each year with high mortality rates, posing a severe worldwide health burden. Lipopolysaccharide (LPS), or endotoxin, a key component of Gram-negative bacterial cell walls, plays a central role in the pathogenesis of sepsis. During sepsis, blood LPS levels can surge thousands-fold, closely correlating with multiple organ failure and mortality risk. Therefore, efficient and specific clearance of LPS from the blood is a crucial therapeutic strategy for curbing early disease progression.

However, achieving specific LPS clearance faces significant challenges: Firstly, the LPS family exhibits complex and diverse structures, with substantial variations in O-antigens and core oligosaccharides among different bacterial species, making broad-spectrum recognition difficult. Secondly, the extremely low concentration of LPS in blood (ng·mL⁻¹ level) severely limits adsorption kinetics. Finally, abundant biomolecules like proteins in blood cause strong interference, compromising the adsorbent's selectivity. Traditional hemoperfusion adsorbents (e.g., activated carbon, polymeric resins) primarily rely on non-specific physical adsorption, removing beneficial blood components (e.g., blood cells, proteins) along with toxins, often leading to serious side effects like coagulation abnormalities and anemia. Although polymyxin B (PMB) immobilization is a common strategy, it carries risks of antibiotic leakage causing nephrotoxicity and neurotoxicity. Thus, developing novel LPS adsorbent materials with high specificity and safety is an urgent need in sepsis treatment.

02 Innovative Highlights

Source Innovation: Discovery of a High-Affinity Peptide Ligand Targeting the LPS "Conserved Core."​ Abandoning the traditional approach targeting variable sugar chains, the team utilized phage display technology with the "Kdo2-lipid A" structure, common to most LPS molecules, as the screening target. This successfully circumvented LPS structural heterogeneity, yielding a novel high-affinity peptide, P-HK (sequence: HHHEISWMTWLK). This peptide demonstrated nanomolar affinity and broad-spectrum neutralizing activity superior to PMB against LPS from various bacterial sources, fundamentally solving the recognition breadth challenge.

Method Innovation: Constructing "Geometrically Matched" Molecularly Imprinted Cavities via Emulsion Interfacial Polymerization.​ Addressing the amphiphilic nature of LPS, this study innovatively employed emulsion interfacial polymerization. This method cleverly exploits LPS's tendency to spontaneously orient at the oil-water interface (hydrophobic lipid A嵌入 oil phase, hydrophilic polysaccharide chain extends into water phase), creating imprinted cavities on the polymer particle surface that are precisely complementary in shape and size to the LPS polysaccharide moiety. This spatial size selectivity adds a second layer of specificity.

Strategy Innovation: Dual-Affinity Synergy Enables Ultra-Specific Capture.​ The study's highlight is the fusion of the above strategies, covalently grafting the P-HK peptide onto the molecularly imprinted polymer (PS@PA+) surface, resulting in the final adsorbent PS@PA-PHK+. This material combines the peptide ligand's high affinity and breadth with the spatial size selectivity of the imprinted cavity. This "dual-verification" mechanism significantly enhances LPS recognition precision, akin to "one key fitting two locks," minimizing non-specific adsorption of other blood components and achieving a paradigm shift from "extensive" adsorption to "precisely targeted" clearance.

Scheme 1. Design strategy for constructing high-specificity LPS adsorbents. A) Origin of LPS and pathogenesis of LPS-induced sepsis, which induces severe organic damage.

03 Results and Discussion

3.1 Validation and Mechanism of the High-Affinity Broad-Spectrum Peptide P-HK

The lead peptide P-HK, selected via phage display, was validated by Bio-Layer Interferometry (BLI) and Isothermal Titration Calorimetry (ITC). Its dissociation constant (KD) for E. coli LPS (E-LPS) reached 4.8 µM, with a binding constant (Ka) of approximately 5.89 × 10⁴ M⁻¹, significantly outperforming PMB. More importantly, P-HK maintained high affinity for LPS from sources like Acinetobacter baumanniiand Salmonella Typhimurium, demonstrating excellent broad-spectrum activity. Alanine scanning mutagenesis combined with molecular docking simulations revealed that key residues (H3, E4, I5, S6, W7) form multiple hydrogen bonds with the LPS glycan moiety, elucidating the molecular recognition mechanism (Figure 1).

Figure 1. Identification of high-affinity LPS-targeting peptides.

3.2 Optimization of Anti-Fouling Polymer Substrate and Molecular Imprinting

Systematic material optimization provided an ideal carrier for the peptide ligand. First, poly(ethylene glycol) methyl ether acrylate (PEGMEA) was screened as the optimal hydrophilic monomer, endowing the material with excellent anti-protein fouling capability (human serum albumin adsorption < 7.8 mg·g⁻¹). Second, by controlling polymerization conditions, polymer microspheres (PS@PA) with a core-shell structure were successfully prepared, whose hydrophilic layer thickness (~16 nm) matched the LPS polysaccharide chain size, and pore size was controlled at ~3 nm, effectively blocking plasma protein entry (Figure 2). Finally, using LPS as a template via emulsion interfacial polymerization, polymer PS@PA+ with precise imprinted cavities was successfully constructed, showing a significantly higher LPS clearance rate (84.6%) compared to the non-imprinted material PS@PA (31.1%), proving the cavity's effectiveness.

Figure 2. Synthesis of P-HK-functionalized polymeric particles and evaluation of their LPS clearance performance.

3.3Excellent Properties of the Dual-Affinity Material PS@PA-PHK+

Grafting P-HK onto the molecularly imprinted polymer yielded the final material PS@PA-PHK+. Performance results were impressive: in PBS buffer, the clearance rate for E-LPS reached 99.2%, with an adsorption capacity of 543 EU·mg⁻¹, far exceeding reported materials. In a more realistic environment (human whole blood), the clearance rate remained high at 95.4%, with minimal plasma protein adsorption, demonstrating exceptional anti-interference ability and specificity. Confocal fluorescence images visually confirmed the specific binding of PS@PA-PHK+ to fluorescently labeled LPS, whereas the non-imprinted material showed almost no binding (Figure 3).

Figure 3. Efficient LPS capture enabled by P-HK-modified imprinted polymers.

3.4 Animal Model Validates Effective Sepsis Treatment

To meet clinical hemoperfusion requirements, PS@PA-PHK+ microspheres were encapsulated within a polyethersulfone (PES) matrix to form a macroscopic composite material (PS@PA-PHK+/PES). This material exhibited excellent hemocompatibility (hemolysis rate < 2%). In an LPS-induced septic rabbit model, a 2-hour hemoperfusion using this material resulted in a 91.4% reduction in circulating LPS levels and a significant decrease in the pro-inflammatory cytokine IL-6 (Figure 4). Histopathological analysis further showed that treatment significantly alleviated sepsis-induced multi-organ damage including acute lung, kidney, and liver injuries. The treatment group achieved a 100% survival rate, compared to only 40% in the control group, strongly demonstrating the adsorbent's in vivo therapeutic efficacy.

Figure 4. In vivo hemoperfusion therapy in a sepsis rabbit model.

04 Conclusion and Future Perspectives

This study successfully integrates biologically oriented high-affinity peptide ligands with materials science-oriented molecular imprinting technology, proposing an innovative "dual-affinity strategy" and subsequently developing the high-performance LPS-specific adsorbent PS@PA-PHK+. This work not only provides a promising new material for blood purification therapy in sepsis but, more importantly, offers a novel solution and methodology for the common challenge of achieving high-specificity capture of low-abundance, highly heterogeneous targets within complex biological systems.

In summary, the strength of this "dual-affinity strategy" lies in its programmability and scalability. Theoretically, by changing the phage display target and the molecular imprinting template, this platform can be widely applied to develop specific adsorbents for other disease-critical factors (e.g., cytokines in hyperinflammation, autoantibodies in autoimmune diseases, specific toxins in uremia). This could propel blood purification technology from the current era of "non-selective broad-spectrum adsorption" (1.0) towards an era of "precisely targeted clearance" (2.0). Although challenges in clinical translation such as large-scale production and long-term biosafety require further evaluation, this study undoubtedly opens a new technical path for the precise treatment of sepsis and other diseases, possessing significant scientific importance and clinical translation potential.

Original Article: 

Wei H, Li X, Xiong Y, et al. Unique Dual-Affinity Strategy for Specific Lipopolysaccharide Clearance in Sepsis Therapy: Peptide-Conjugated Molecularly Imprinted Polymers via Emulsion Interfacial Polymerization. Adv Mater. 2025 Nov 20:e17135. 

https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202517135