Writing in the journal Materials Today Bio, researchers led by Chen Zhang, Shanying Han, and Ruiyao Zhou describe a reactive oxygen species-responsive, small-molecule self-assembled nanocarrier integrated into a hydrogel, which they call HA/MPC@B. The central insight is that inflamed colonic tissue is chemically distinctive: it is bathed in abnormally high concentrations of reactive oxygen species, the volatile molecules that drive oxidative stress and destroy the protective gastrointestinal mucosal layer. Rather than fighting this harsh chemistry, the team exploits it as a trigger. The system is built around a borate ester group derived from pinacol 4-hydroxyphenylborate, a chemical bond that remains stable in ordinary physiological conditions but cleaves selectively when it encounters the elevated reactive oxygen microenvironment of a colitis lesion. This means the drug stays locked away during its journey through the stomach and healthy intestine and is released preferentially at the site of disease.

The construction of the nanocarrier itself is a feat of molecular design accomplished in three steps. First, the researchers coupled pinacol 4-hydroxyphenylborate with 1,1′-carbonyl diimidazole, producing an intermediate with non-toxic, removable imidazole as the only by-product. Second, under catalysis by 4-dimethylaminopyridine, this intermediate was covalently crosslinked with D-mannose, a sugar that serves double duty as a hydrophilic anchor and, crucially, as a targeting ligand. The resulting amphiphilic molecules self-assemble spontaneously in water into nanoparticles roughly 160 to 170 nanometers in diameter, with a hydrophilic outer shell of mannose polyhydroxy groups and amide bonds surrounding a hydrophobic core of phenyl rings and ether linkages. Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance collectively confirmed each stage of synthesis, tracking the disappearance and emergence of characteristic peaks for hydroxyl, carbonyl, boronate ester, imidazole, and sugar-ring groups.

Into these self-assembled spheres, the team loaded berberine, a natural plant-derived compound with well-documented anti-inflammatory, antibacterial, barrier-repairing, and microbiota-regulating effects, but notoriously poor solubility and bioavailability. Dynamic light scattering showed the loaded nanoparticles had a mean diameter of about 160 nanometers and a surface zeta potential of minus 33.13 millivolts. Encapsulation efficiency reached 77.93 plus or minus 2.87 percent, with a drug loading capacity of 23.76 plus or minus 0.67 percent, figures that underscore the exceptional loading power of small-molecule self-assembly. Transmission electron microscopy revealed a higher electron density in the interior of loaded particles compared with empty ones, a direct visual signature that berberine sat packed inside. Stability testing in simulated gastric, intestinal, and colonic fluids showed the particles held together through intestinal and colonic transit, yet visibly disassembled in simulated gastric fluid and, tellingly, in colonic fluid spiked with hydrogen peroxide to mimic the inflamed colon.

The final layer of the system is a hybrid hydrogel of hyaluronic acid and hyaluronate methacrylate, a biodegradable and biocompatible matrix that is injectable and shear-thinning, meaning its viscosity drops under force so it flows easily yet reforms a stable gel afterward. Scanning electron microscopy showed the composite formed an interconnected three-dimensional porous skeleton whose irregular pores facilitate diffusion of the nanoparticles and strengthen their adhesion to the intestinal wall. In drug release assays across 48 hours, the hydrogel held cumulative berberine release below 20 percent in neutral buffer, simulated gastric fluid, simulated intestinal fluid, and simulated colonic fluid. But in colonic fluid supplemented with 0.1 millimolar hydrogen peroxide, mimicking the high-reactive oxygen environment of inflamed tissue, cumulative release jumped to 52.02 plus or minus 4.11 percent. The hydrogel also delayed release compared with bare nanoparticles, acting as a depot that guards against premature leakage while the payload travels to the colon.

Safety came first in the evaluation. Cytotoxicity testing on Caco-2 intestinal epithelial cells showed no significant loss of viability at berberine-equivalent concentrations up to 1.0 milligram per milliliter, the concentration chosen for all subsequent experiments. Hemolysis assays demonstrated a hemolysis rate below 5 percent, meeting the accepted criterion for biomedical materials, and live/dead staining over 72 hours showed living cells dominating every treatment group at every time point. Targeting was verified with striking clarity in RAW264.7 macrophages. A fluorescent mannose probe was avidly internalized by the cells, but when the researchers pre-blocked the mannose receptor with free mannose or competed with unlabeled nanoparticles, fluorescence plummeted; flow cytometry quantified mean fluorescence falling from 71.9 in the probe-only group to 31.5 in the competition group. This proved the mannose-decorated nanoparticles specifically recognize macrophage mannose receptors, which are overexpressed on inflammatory immune cells at lesion sites.

The therapeutic action proved multimodal. In macrophages stimulated with lipopolysaccharide to mimic a hyperinflammatory state, the loaded nanoparticles and the full hydrogel suppressed the pro-inflammatory M1 phenotype, marked by CD86, and restored the anti-inflammatory M2 phenotype, marked by CD206. Gene expression analysis showed tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 all falling, while the anti-inflammatory interleukin-10 rebounded above control levels. The system also scavenged reactive oxygen species broadly, neutralizing hydroxyl radicals, hydrogen peroxide, and superoxide anions in cell-based assays. In DSS-injured Caco-2 monolayers, treatments accelerated cell migration in scratch-wound assays, reduced FITC-dextran leakage across the epithelium, and restored the tight junction proteins ZO-1 and Claudin-1 along with their messenger RNA, evidence that the damaged intestinal barrier was genuinely being rebuilt, not merely soothed.

In vivo results in a mouse model of acute colitis, induced by dextran sulfate sodium in drinking water, confirmed the design logic. Mice receiving the hydrogel by oral gavage showed the best weight recovery among all treatment groups, higher survival, reduced disease activity index scores, suppressed splenomegaly, and reversal of colon shortening. Fluorescence imaging with Cy5.5-labeled formulations revealed the difference decisively: free dye vanished within hours, bare nanoparticles leaked fluorescence throughout the digestive tract within four hours after gastric acid exposure, but the hydrogel-protected formulation produced intense, sustained fluorescence in the inflamed colon from 4 to 36 hours after administration, because the crosslinked matrix shields the nanoparticles from stomach acid until they reach their target. Histology showed the lowest pathological scores in the hydrogel group, myeloperoxidase staining revealed sharply reduced neutrophil infiltration, and serum FITC-dextran levels confirmed restored barrier integrity. A healthy control group given the hydrogel showed no adverse changes, indicating good biosafety at the therapeutic dose.

Perhaps most remarkably, 16S rRNA sequencing and transcriptomic analysis traced the therapy’s effects deep into biology. Colitis had disrupted the gut microbiome, enriching pro-inflammatory genera such as Helicobacter, Escherichia-Shigella, Rothia, and Moraxella while depleting beneficial taxa like Muribaculaceae and Alloprevotella; the hydrogel treatment reversed this dysbiosis, restoring microbial profiles that clustered with healthy controls. Transcriptome sequencing of colonic tissue found 385 genes upregulated and 196 downregulated after treatment, with cell proliferation and epithelial regeneration genes such as Lgr5, Agr2, and Cldn8 rising while pyroptosis and inflammatory genes including Casp4, Nos2, Il17a, and Gsdmd fell. Gene ontology analysis showed suppression of NF-kappaB and NLRP3 inflammasome pathways, confirmed by quantitative PCR showing reduced Tlr4 and Rela and increased Nfkbia. Together, these layers of evidence, from molecular cleavage chemistry to microbiome ecology, present HA/MPC@B as an intelligent, multifunctional platform that treats ulcerative colitis through targeted delivery, on-demand drug release, antioxidant and immune modulation, barrier repair, and microbiota remodeling, offering a compelling blueprint for clinical translation.

Subject of Research: A ROS-responsive small-molecule self-assembled nanocarrier-integrated hydrogel for targeted treatment of ulcerative colitis

Article Title: ROS-responsive small-molecule self-assembled nanocarrier-integrated hydrogels for ulcerative colitis treatment

Article References: ROS-responsive small-molecule self-assembled nanocarrier-integrated hydrogels for ulcerative colitis treatment. (n.d.). https://doi.org/10.1016/j.mtbio.2026.103684

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103684

Keywords: ulcerative colitis, ROS-responsive drug delivery, nanocarriers, hydrogel, berberine, hyaluronic acid, macrophage polarization, intestinal barrier, gut microbiota, NF-kappaB signaling, oxidative stress, drug targeting

The hydrospongel is ingeniously designed to mimic the natural tubular architecture of the colon, providing a biomimetic scaffold that interfaces intimately with tumor tissues. This hollow-tube-like structure is more than structural mimicry; it facilitates localized, sustained release of therapeutic agents directly to the tumor microenvironment. By precisely controlling the spatial and temporal distribution of drugs, the hydrospongel enhances the penetration of chemotherapeutic compounds, immunomodulators, and other bioactive molecules, overcoming barriers imposed by dense extracellular matrices and irregular vasculature typically found in colorectal tumors.

From a materials science perspective, the hydrospongel leverages a hydrogel-based matrix characterized by high porosity coupled with mechanical robustness. Its composition lends itself to high water content, ensuring biocompatibility and minimal cytotoxicity, while simultaneously providing the necessary elasticity to conform to biological tissues without causing mechanical damage. The porous nanostructure is optimized to enable efficient loading and controlled release kinetics, a feat achieved through precise manipulation of polymer crosslinking densities and incorporation of stimuli-responsive elements that react to the local physiological environment.

One of the standout features of this hydrospongel is its ability to support multimodal therapy paradigms. Whereas traditional cancer treatments often rely on monotherapy regimens that can lead to resistance and incomplete eradication of malignant cells, the hydrospongel serves as a multifunctional platform that orchestrates the delivery of chemotherapy in conjunction with immunotherapy and photothermal therapy. This multimodal approach synergistically assaults cancer cells, weakening tumor resilience and reducing the likelihood of recurrence or metastasis.

The researchers meticulously demonstrated the efficacy of their device in preclinical models of advanced colorectal cancer, where they observed remarkable tumor regression and improved survival rates compared to traditional treatment methods. Importantly, the hydrospongel-mediated therapies elicited minimal systemic toxicity, underscoring its potential to enhance patient quality of life by mitigating common side effects associated with chemotherapy and immunotherapy. This selective targeting is particularly critical given the sensitive nature of colorectal tissues and the high risk of collateral damage during aggressive treatment protocols.

Mechanistically, the platform capitalizes on its hollow tubular design to facilitate intratumoral insertion, ensuring direct contact with malignant tissues. The spongy matrix acts as a reservoir, soaking up therapeutic agents and gradually releasing them as the gel matrix degrades or responds to environmental cues such as pH changes and enzymatic activity common in tumor microenvironments. Coupled with this, the system’s compatibility with near-infrared light enables photothermal therapy, whereby localized heating induced by light absorption selectively ablates cancer cells, while sparing surrounding healthy tissue.

The incorporation of immunotherapeutic agents further augments the hydrospongel’s efficacy by invigorating local immune responses. The delivery system enhances antigen presentation and recruits cytotoxic T lymphocytes to the tumor site, converting the often immunosuppressive tumor microenvironment into one conducive to immune-mediated eradication. This is a significant breakthrough given the known immunoevasive capabilities of colorectal tumors, which frequently diminish the effectiveness of checkpoint inhibitors and other immunomodulatory treatments when administered systemically.

Crucially, the design also allows for customization of drug combinations and dosages tailored to individual patient tumor profiles, aligning with the growing trend towards personalized medicine. By modulating the hydrogel’s composition and drug payload, clinicians could, in principle, tailor the therapeutic cocktail to exploit specific vulnerabilities within a patient’s tumor genotype and phenotype, thereby maximizing treatment outcomes and minimizing unnecessary exposure to ineffective agents.

The translational potential of this hydrospongel is underscored by its ease of fabrication and scalability. Utilizing bio-friendly and FDA-approved materials enhances the likelihood of swift clinical adoption, while the manufacturing process can be adapted to produce size- and shape-specific hydrogels suited for varied tumor morphologies and locations. Furthermore, the platform’s adaptability extends beyond colorectal cancer, opening avenues for its application across other solid tumors in anatomically challenging or sensitive sites requiring localized treatment.

Beyond tumor therapy, the hydrospongel platform could serve as a diagnostic tool by incorporating imaging agents that allow real-time monitoring of drug release and tumor response via non-invasive imaging modalities. Such real-time feedback mechanisms would be invaluable for clinicians in adjusting therapeutic protocols dynamically and improving longitudinal patient outcomes.

The interpretability of this technology stands out as well; extensive characterization studies demonstrated the relationship between hydrogel microarchitecture and its mechanical, chemical, and biological performance, providing a solid framework for rational design enhancements. Insights from these studies pave the way for the next generation of responsive biomaterials capable of adapting to fluctuating tumor environments and evolving therapeutic needs.

Collaborative efforts across materials science, oncology, and immunology have been critical in bringing this project to fruition. The convergence of expertise has fostered a comprehensive approach that simultaneously addresses the physicochemical hurdles of drug delivery, the biological complexities of tumor heterogeneity, and the clinical imperatives for minimally invasive yet highly effective therapeutics.

As this technology advances towards clinical trials, the anticipation is palpable within the cancer research community. The hollow-tube-like hydrospongel could well become a torchbearer for future multifunctional drug delivery systems, setting a new standard in the treatment paradigm for colorectal cancer and potentially revolutionizing the approach to combating other intractable malignancies.

This breakthrough serves as a testament to how biomimicry combined with state-of-the-art materials engineering can forge novel therapeutics that transcend traditional boundaries. The hydrospongel’s marriage of mechanical ingenuity and therapeutic sophistication represents a bold stride towards the holy grail of cancer treatment—a modality that is simultaneously targeted, multimodal, patient-friendly, and efficacious, transforming prognosis from bleak to hopeful for patients battling advanced colorectal cancer.

With colorectal cancer incidence and mortality rates climbing globally, innovations such as this hydrospongel bring a much-needed breath of fresh air to a field urgently seeking more effective and less toxic treatment regimens. If successful in clinical translation, this strategy promises not only to extend patient survival but to enhance life quality by disentangling efficacy from toxicity.

The future trajectory of this technology is ripe with possibilities. Further exploration into integrating genetic and metabolic sensors within the hydrospongel could elevate it from a mere drug delivery vehicle to a smart therapeutic device—capable of sensing tumor microenvironment changes and autonomously adapting treatment regimens in real-time, thereby pushing the frontiers of personalized oncology.

In conclusion, the innovative hollow-tube-like hydrospongel embodies a paradigm shift in the design of hydrogels for cancer therapy. Its multifaceted capabilities in delivering localized, multimodal treatment modalities mark a seminal milestone in the battle against colorectal cancer, with broader implications for precision medicine and drug delivery sciences. This technology heralds a new epoch where biomaterial scaffolds evolve beyond passive carriers to become active participants in therapeutic intervention, offering hope and renewed vigor against one of the most daunting challenges in modern medicine.

Subject of Research: Advanced colorectal cancer therapy using a novel biomimetic hydrospongel for localized multimodal treatment.

Article Title: A hollow-tube-like hydrospongel for multimodal therapy of advanced colorectal cancer.

Article References:
Wu, T., Li, T., Zhang, C. et al. A hollow-tube-like hydrospongel for multimodal therapy of advanced colorectal cancer. Nat Commun 16, 7464 (2025). https://doi.org/10.1038/s41467-025-62880-x

Image Credits: AI Generated