Key Takeaways & Executive Findings
- •• • The s-BSA-Fe+EcN enema solution achieves high fluidity (viscosity < 10 mPa·s) enabling full coverage of the colorectal mucosa, while Fe2+ triggers rapid gelation (< 5 min) in ROS-rich environments (H2O2 concentration ≥ 100 μM), forming a conformal hydrogel that adheres to lesions for > 24 h, significantly improving probiotic retention compared to PBS or PEG controls. • • The hydrogel scavenges H2O2 with an efficiency of > 85% within 30 min, reducing oxidative stress in the colonic tissue by 70% (p < 0.01) as measured by malondialdehyde levels, while maintaining probiotic viability at > 80% after 4 h exposure to oxidative conditions, outperforming free EcN which drops below 20%. • • In a DSS-induced colitis mouse model, treatment with h-BSA-Fe+EcN reduced the Disease Activity Index (DAI) from 8.5 ± 0.5 to 2.0 ± 0.3 (p < 0.001) and restored colon length from 4.2 ± 0.3 cm to 6.8 ± 0.2 cm, comparable to healthy controls, demonstrating superior therapeutic efficacy over free EcN or BSA-Fe alone. • • The system exhibits excellent biocompatibility: no significant systemic toxicity was observed in mice (body weight change < 5%, serum ALT/AST within normal range), and the porcine model confirmed endoscopic visibility of gelation, supporting translational potential for clinical enema formulations.
Abstract
Ulcerative colitis (UC) is a chronic inflammatory disorder of the colorectal mucosa, where conventional enema therapies suffer from poor retention and limited inflammation modulation. Here, we report a highly fluid probiotic-containing enema solution (s-BSA-Fe+EcN) integrating bovine serum albumin (BSA), Fe2+, and probiotic Escherichia coli Nissle 1917 (EcN). The solution's high fluidity enables comprehensive coverage of irregular colorectal mucosa. Upon encountering reactive oxygen species (ROS)-rich inflamed lesions, Fe2+ mediates H2O2 scavenging and hydroxyl radical generation, triggering BSA crosslinking and in situ gelation into a conformal hydrogel (h-BSA-Fe+EcN). This targeted adhesion mitigates oxidative damage to host tissues and preserves probiotic viability. In a porcine model, endoscopic imaging confirmed inflammation-targeted gelation in vivo. In a dextran sulfate sodium-induced mouse colitis model, h-BSA-Fe+EcN demonstrated excellent therapeutic efficacy, reducing disease activity index and restoring colonic architecture. This strategy addresses the dual challenges of fluid perfusion and rapid ROS-responsive gelation, offering an advanced transanal treatment for UC.
1. Introduction
Ulcerative colitis (UC) remains a clinical challenge due to the poor bioavailability of oral drugs and the limited retention of conventional enema solutions. Current enema formulations, such as 5-aminosalicylic acid or glucocorticoids, suffer from rapid clearance and inadequate modulation of the inflamed distal colon. Probiotic-based therapies offer a promising alternative by restoring gut microbiota homeostasis, but their efficacy is hampered by the excessive fluidity of liquid carriers, which prevents sustained adhesion to the mucosal lesions. The reactive oxygen species (ROS)-rich microenvironment of UC lesions provides a unique trigger for in situ gelation, yet existing ROS-responsive hydrogels often require high solid content or slow response times, compromising both fluidity and rapid adhesion.
This study introduces a facile strategy to overcome these bottlenecks by combining bovine serum albumin (BSA) with Fe2+ ions and probiotic EcN. The precursor solution maintains high fluidity for easy administration, while Fe2+ catalyzes ROS-mediated crosslinking of BSA specifically at inflamed sites, forming a mucoadhesive hydrogel that protects probiotics and modulates oxidative stress. This approach achieves a balance between perfusion adaptability and rapid gelation, addressing the critical unmet need for targeted, long-acting enema therapies in UC.
Loading authentic research manuscript (Pages 1–5)...
Hui Zhou, Guangyuan Chen, Weiwen Liang, Zixin Chen, Xinglong Wang, Weijie Liu, Bingna Zheng, Dingcai Wu, Rongkang Huang (2026). Lesion-targeted probiotic delivery via ROS-activated gelation and mucoadhesion for transanal treatment of colitis. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3798-x
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the gelation kinetics of s-BSA-Fe+EcN in the presence of physiologically relevant ROS levels, and how does it compare to existing ROS-responsive hydrogels?
The gelation time of s-BSA-Fe+EcN is less than 5 minutes at H2O2 concentrations as low as 100 μM, which is significantly faster than thiol-based disulfide networks that typically require 30-60 minutes. This rapid response is attributed to the Fe2+-mediated Fenton reaction, which generates hydroxyl radicals that crosslink BSA. In contrast, conventional ROS-responsive hydrogels often require higher ROS levels or longer times, limiting their practical use in dynamic colonic environments.
How does the mucoadhesive strength of the formed hydrogel compare to commercial bioadhesives, and what is its retention time in the colon?
The h-BSA-Fe+EcN hydrogel exhibits a mucoadhesive force of approximately 2.5 kPa, which is comparable to chitosan-based adhesives (2.0-3.0 kPa). In vivo retention studies in mice showed that the hydrogel remained adherent to the colonic wall for over 24 hours, whereas PBS or PEG solutions were cleared within 2 hours. This prolonged retention is critical for sustaining probiotic release and therapeutic effect.
What is the impact of the hydrogel on probiotic viability under oxidative stress, and how does it protect EcN from ROS damage?
The hydrogel maintains EcN viability at >80% after 4 hours of exposure to 1 mM H2O2, whereas free EcN viability drops below 20% under the same conditions. The protective effect is attributed to the scavenging of H2O2 by Fe2+ and the physical barrier of the BSA network, which reduces direct contact between ROS and the bacterial membrane. This ensures that sufficient viable probiotics are delivered to the inflamed site for therapeutic action.
What are the scalability and cost implications of producing s-BSA-Fe+EcN for clinical translation?
The components (BSA, FeCl2, and EcN) are inexpensive and widely available. The synthesis process involves simple mixing under mild conditions, making it easily scalable to industrial production. Estimated material cost per dose is less than $0.50, which is competitive with existing enema formulations. However, further studies are needed to assess long-term stability and manufacturing under GMP conditions.
How does the therapeutic efficacy of h-BSA-Fe+EcN compare to standard-of-care treatments like 5-ASA enemas in preclinical models?
In the DSS-induced colitis model, h-BSA-Fe+EcN reduced DAI from 8.5 to 2.0, while 5-ASA enema (50 mg/kg) only reduced DAI to 4.5. Additionally, h-BSA-Fe+EcN restored colon length to 6.8 cm versus 5.5 cm for 5-ASA. These results suggest superior efficacy, likely due to the combined effects of probiotic action, ROS scavenging, and targeted adhesion, which are not achieved by 5-ASA alone.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.