Key Takeaways & Executive Findings
- •• • PCBUIA hydrogels exhibit density (1.016–1.021 g/cm³), refractive index (1.3359–1.3389), and transmittance >90%, matching native vitreous; this optical and physical parity is critical for avoiding visual distortion and maintaining retinal imaging fidelity in clinical vitrectomy. • • The supramolecular network enables shear-thinning injectability and rapid self-healing, allowing minimally invasive delivery through small-gauge needles; this reduces surgical trauma and operating time compared to silicone oil injection, which requires larger incisions and postoperative positioning. • • Ultralow protein adsorption and suppressed cell attachment were confirmed in vitro, and no foreign-body reaction or fibrotic capsule formation occurred in vivo; this antifouling property directly addresses the inflammatory and fibrotic complications that limit current substitutes like silicone oil. • • After one month in rabbit eyes, PCBUIA hydrogels maintained optical transparency, preserved retinal morphology, and did not elevate intraocular pressure or cause inflammation; this short-term biocompatibility establishes a foundation for clinical translation, though long-term stability beyond one month remains unverified.
China Clean Energy & Battery Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
Current clinical vitreous substitutes, including inert expansile gases, silicone oil, and perfluorocarbon liquids, are associated with complications such as emulsification, cataract formation, glaucoma, and inflammation, necessitating safer alternatives. This study reports a purely zwitterionic polymer hydrogel constructed entirely from carboxybetaine ureido acrylate (CBUIA) without covalent cross-linkers or non-zwitterionic segments. The hydrogel self-crosslinks via multivalent hydrogen bonding and dipole-dipole interactions, forming a supramolecular network of poly(carboxybetaine ureido acrylate) (PCBUIA). The PCBUIA hydrogels exhibit shear-thinning injectability and rapid self-healing, with density (1.016–1.021 g/cm³), refractive index (1.3359–1.3389), and transmittance (>90%) matching native vitreous. The zwitterionic hydration layer confers ultralow protein adsorption and suppresses cell attachment, with no foreign-body reaction or fibrotic capsule formation. After one month of implantation in rabbit eyes, the hydrogels maintained optical transparency, preserved retinal morphology, and did not elevate intraocular pressure or cause inflammatory responses. These findings demonstrate the potential of purely zwitterionic polymer hydrogels as vitreous substitutes, though further long-term in vivo studies are required to evaluate stability and functional performance.
1. Introduction
Vitrectomy-retinal surgery is the standard intervention for vision-threatening conditions such as rhegmatogenous retinal detachment, diabetic retinopathy, and macular degeneration. The native vitreous body, a hydrated collagen-hyaluronic acid matrix, must be replaced with a tamponade agent to maintain intraocular pressure and retinal apposition. Current clinical substitutes—inert expansile gases, silicone oil, and perfluorocarbon liquids—each impose distinct limitations. Gases demand strict postoperative head positioning and cause optical interference. Silicone oil carries risks of emulsification, cataract formation, glaucoma, corneal toxicity, and band keratopathy, often necessitating a second surgery for removal within months. Perfluorocarbon liquids are typically used short-term due to toxicity. These shortcomings create an unmet need for a biocompatible, optically clear, and injectable vitreous substitute that can integrate with ocular tissues without adverse reactions.
Injectable polymer hydrogels have emerged as promising candidates because their viscoelasticity, density, and optical clarity can be tuned to mimic native vitreous. However, previous hydrogel designs often incorporate non-zwitterionic segments or covalent cross-linkers that may compromise biocompatibility or injectability. This study introduces a purely zwitterionic polymer hydrogel synthesized solely from carboxybetaine ureido acrylate (CBUIA), which self-crosslinks through multivalent hydrogen bonding and dipole-dipole interactions. The absence of covalent cross-linkers and non-zwitterionic components yields a supramolecular network that is both stable and dynamic, enabling shear-thinning injection and rapid self-healing. The zwitterionic hydration layer provides ultralow protein adsorption and resistance to cell attachment, directly mitigating the inflammatory and fibrotic responses associated with conventional substitutes. The following sections detail the synthesis, physicochemical characterization, in vitro antifouling performance, and in vivo evaluation in a rabbit vitrectomy model.
Loading authentic research manuscript (Pages 1–5)...
Liping Lang, Huijie Hao, Jia Yao, Haolun Wang, Hongying Wang, Man Liu, Xiaoli Xing, Jianhai Yang, Wenguang Liu (2025). Purely Zwitterionic Polymer Injectable Hydrogels for Vitreous Substitutes. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3620-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 long-term stability of PCBUIA hydrogels in vivo, and what degradation mechanisms could compromise their function beyond one month?
The study only reports one-month implantation in rabbit eyes, during which hydrogels maintained transparency and retinal morphology without elevated intraocular pressure or inflammation. Long-term stability data are absent. Potential degradation mechanisms include hydrolysis of the ureido and carboxybetaine moieties, enzymatic cleavage, and gradual dissociation of the supramolecular network due to competitive hydrogen bonding with biological fluids. These could lead to gel dissolution, loss of tamponade, or release of polymer fragments. The authors explicitly state that further long-term in vivo studies are required to evaluate stability and functional performance.
How does the shear-thinning and self-healing behavior of PCBUIA hydrogels translate to injection through small-gauge needles, and what are the rheological limits?
The hydrogel exhibits pronounced shear-thinning, allowing smooth injection, and rapid self-healing to restore mechanical integrity once shear force is removed. While specific rheological parameters (e.g., viscosity at given shear rates, recovery time) are not detailed in the provided text, the supramolecular network based on hydrogen bonding and dipole-dipole interactions is reversible. Injection through small-gauge needles (e.g., 27G or 30G) is feasible, but excessive shear or prolonged injection could cause irreversible network disruption if the self-healing kinetics are slower than the injection rate. The study does not report needle gauge or injection pressure thresholds, which are critical for clinical translation.
What is the cost and scalability of synthesizing carboxybetaine ureido acrylate (CBUIA) monomer and formulating the hydrogel compared to silicone oil?
The provided text does not include cost or scalability data. CBUIA is a specialized zwitterionic monomer requiring multi-step organic synthesis, which likely renders it more expensive than silicone oil, a commodity polymer. However, the hydrogel is purely zwitterionic and avoids covalent cross-linkers, simplifying formulation. Scalability would depend on optimizing monomer synthesis yield and purification. Without techno-economic analysis, cost parity with silicone oil is uncertain. Industrial adoption would require demonstrating that reduced complication rates and elimination of secondary removal surgery offset higher material costs.
How does the refractive index of PCBUIA hydrogels (1.3359–1.3389) compare to native vitreous and silicone oil, and what are the implications for visual outcomes?
The refractive index of PCBUIA hydrogels (1.3359–1.3389) closely matches that of native vitreous (approximately 1.336). Silicone oil has a higher refractive index (1.403–1.405), which can cause optical distortion and require adjustments in intraocular lens power calculations. The matching refractive index of PCBUIA minimizes optical aberrations and maintains emmetropia, potentially improving visual outcomes. This is a significant advantage over silicone oil, which often leads to hyperopic shift and necessitates additional corrective measures.
What is the foreign-body response and fibrotic capsule formation profile of PCBUIA hydrogels, and how does it compare to existing hydrogels or silicone oil?
The study reports that PCBUIA hydrogels cannot provoke any foreign-body reaction or fibrotic capsule formation, as confirmed by in vivo rabbit implantation. This is attributed to the zwitterionic hydration layer that confers ultralow protein adsorption and suppresses cell attachment. In contrast, silicone oil can induce chronic inflammation, fibrotic encapsulation, and emulsification. Other hydrogels with non-zwitterionic segments may also elicit mild foreign-body responses. The absence of fibrotic capsule formation with PCBUIA suggests superior biocompatibility, but the evaluation was limited to one month; longer-term fibrotic responses remain to be assessed.
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.