Journal of materials chemistry. B最新文献

The emergence of antibiotic-resistant bacterial infections mainly due to the proliferation of bacterial biofilms poses a critical clinical challenge. The low efficacy of currently used antibacterial agents, caused due to their poor penetration into biofilms, hinders their therapeutic potential. Here, we report a drug-free, nanozyme-based, self-propelling Janus nanobot engineered to penetrate bacterial biofilms and eradicate drug-resistant pathogens through a synergistic physical-chemical mechanism. The nanobot is fabricated using magnesium (Mg) nanoparticles as a propulsion core, which generate hydrogen bubbles upon reaction with water, and a hemispherical copper oxide (CuO) shell that imparts catalytic and bactericidal activities. The CuO shell catalyses Fenton-like reactions in response to elevated hydrogen peroxide levels within bacterial microenvironments, producing reactive oxygen species (ROS) that induce oxidative stress, membrane disruption, and cell death. Autonomous propulsion enables the nanobots to actively traverse the dense extracellular polymeric matrix of biofilms, thereby enhancing the antibacterial effect. The Mg-CuO (MCO) nanobots achieved efficient biofilm removal and significant reduction in cell viability against S. aureus (MIC - 256 µg mL^-1), P. aeruginosa (MIC - 512 µg mL^-1), and MRSA (MIC - 1024 µg mL^-1). This drug-free, self-powered nanozyme platform effectively overcomes diffusion-limited biofilm barriers and demonstrates potent activity against antibiotic-resistant bacteria, offering strong translational potential for the treatment of chronic and drug-resistant infections.

Cellular imaging is a pivotal strategy for unraveling complex biological processes, disease mechanisms, and drug responses, wherein benzimidazole-acrylonitriles are emerging as promising yet underexplored fluorogenic scaffolds for advanced imaging and therapeutic applications. In the present study, five benzimidazole-acrylonitrile conjugates bearing nitrogen-rich heterocycles were synthesized and systematically investigated for their photophysical characteristics and aggregation-induced emission (AIE) behaviour. The synthetic strategy involves a stepwise condensation of o-phenylenediamine with ethyl cyanoacetate, followed by an L-proline-catalyzed condensation of the resulting intermediate with nitrogen-rich arylaldehydes. The molecular structures of the synthesized compounds were confirmed by ¹H and ¹³C NMR spectroscopy and high-resolution mass spectrometry (HRMS); the structure of compound 5 was further unambiguously established by single-crystal X-ray diffraction analysis. Optical studies revealed distinct absorption and emission features attributable to the hybridized local and charge transfer excited state (HLCT), along with pronounced aggregation-induced emission (AIE) behavior in THF/water mixtures. The observed AIE characteristics were further supported by scanning electron microscopy (SEM) and dynamic light scattering (DLS), which revealed the formation of well-defined aggregated morphologies. All compounds demonstrated classic molecular-rotor-type fluorescence enhancement with increasing viscosity using a DMSO-glycerol mixture and showed distinct pH-responsive emission governed by protonation dynamics within the biological pH range, highlighting their potential as robust probes for visualizing intracellular heterogeneity and acidic microenvironments. Density functional theory (DFT) calculations provided complementary insights into the electronic structure and optical transitions. Remarkably, compound 1 exhibited efficient cytoplasmic localization in live HeLa cells, demonstrating its potential utility as a fluorescent bioimaging probe. Collectively, these findings establish benzimidazole-acrylonitrile conjugates as a new class of AIE-active luminogens with promising applications in precision bioimaging, tumor diagnostics, and theranostic platforms.

MXene-loaded hydrogels represent a promising class of multifunctional biomaterials that combine the remarkable physicochemical properties of MXenes with the adjustable structure and biocompatibility of hydrogels for tissue regeneration. Due to their distinctive two-dimensional structure, elevated surface area, electrical conductivity, and plentiful surface functional groups, MXenes promote improved cell adhesion, proliferation, and differentiation while enhancing bioelectronic communication inside tissues. When incorporated into hydrogel matrices, these nanoparticles enhance mechanical strength, electrical responsiveness, and antibacterial properties, thereby addressing key challenges in tissue-engineering scaffolds. Recent advancements have demonstrated their efficacy in enhancing wound healing, regenerating bone and cartilage, and improving drug delivery. Notwithstanding these considerable accomplishments, obstacles persist regarding long-term biosafety, degradation management, and the scalable production of MXene-based composites. This review comprehensively examines recent advancements in the synthesis, functionalization, and biomedical applications of MXene-loaded hydrogels, critically assesses their existing limitations, and delineates future research directions for their safe and effective clinical implementation in regenerative medicine.

Protein-based hydrogels crosslinked using dithiolanes provide a promising viscoelastic matrix for soft tissue engineering and regenerative medicine including the neural niches due to their inherent biocompatibility, bioactivity, and adaptable extracellular matrix (ECM)-like viscoelastic behavior. Recently, we developed gelatin-dithiolane (GelDT) as a new class of ECM-mimicking viscoelastic hydrogels that displayed multi-functional properties, stimuli responsiveness and enabled independent tuning of the stiffness and matrix stress relaxation rate to precisely tune the matrix for improved cellular functions. However, the synthesis of GelDT remained laborious and inefficient. Herein, we report a scalable, one-step synthesis of GelDT that enables precise control over dithiolane functionalization (3-97%) using a carbonate-bicarbonate buffer system under mild aqueous conditions, while reducing organic solvent consumption from liters to the milliliters scale and eliminating the use of reducing agents. GelDT hydrogels obtained using the new synthesis route exhibit high stability (weeks), tunable stiffness, shear thinning, and self-healing properties essential for minimally invasive delivery. Additionally, pre-gelation tuning via physiochemical crosslinking allowed the fabrication of GelDT hydrogels at a remarkably low gelatin concentration (1.5% w/v) while ensuring fast gelation. The GelDT hydrogel supported the high viability and metabolic activity of encapsulated human iPSC-derived neural progenitor cell (NPC) spheroids. The GelDT hydrogel maintained NPC stemness (SOX2+, Ki-67+) and facilitated successful neuronal differentiation (MAP2+) in 3D culture. This work establishes a scalable, cytocompatible platform for producing dynamic protein-based hydrogels for regenerative medicine.

Bacterial infection usually exacerbates inflammation and is one of the important factors impeding wound healing. At present, dressings for treating wound infections often include antibiotics, silver ions, fibers, etc., but their therapeutic efficacy is still limited. To enhance antibiotic effectiveness and overcome drug resistance, developing efficient drug delivery systems is imperative. Herein, we rationally designed a three-component peptide hydrogel Nap-Phe-Phe-Thr-Asp-Asp-Tyr (NapFFTDDY) co-encapsulating the photosensitizer indocyanine green (ICG) and ciprofloxacin (Cip) to establish a novel antibacterial strategy combining antibiotic therapy with photothermal treatment. This system enables synergistic eradication of diverse bacteria. The peptide molecule could co-assemble with ICG and Cip to form hydrogel networks. Under near-infrared (NIR) irradiation, the ICG loaded with this hydrogel can rapidly heat up and generate hyperthermia, acting as an antibacterial factor together with the released antibiotics, simultaneously achieving potent photothermal therapy and long-term sustained release of drugs. In vitro and in vivo experimental results demonstrated that the peptide hydrogel loaded with both Cip and ICG exhibited a superior bacterial clearance effect compared to free Cip or peptide hydrogel encapsulated only with Cip. Moreover, it significantly alleviated inflammation in the mouse wound model with bacterial infection and significantly accelerated wound closure. This tri-component supramolecular peptide hydrogel offers a novel perspective for developing other advanced antimicrobial agents against wound infections.

Recently, lipid-polymer nanoparticles incorporating bile acids (BAs) have garnered significant interest in drug delivery research. Due to their amphiphilic nature, self-assembling properties, and steroid skeleton, BAs can serve as both drug-solubilizing and membrane-penetrating agents, facilitating drug transport across cell membranes. BAs exhibit diverse bioactivities, including anticancer, antimicrobial, and immunomodulatory effects, which further increase their potential for therapeutic applications. Their carboxyl and hydroxyl functional groups allow for easy derivatization, enabling the synthesis of a wide range of BA-based (macro)molecules. Introducing BAs into polymer systems leads to stable and biocompatible nanocarriers with high affinity to cell membranes, enabling the encapsulation, delivery, and controlled release of bioactive molecules. This review provides a comprehensive overview of polymers containing bile acids (BAs) as drug delivery vehicles. We first explore the biological roles and therapeutic potential of BAs. This is followed by a discussion of the synthetic strategies used to prepare polymers containing bile acid moieties. Finally, we assess the advantages and key challenges that will shape the future development of polymeric BA-based drug delivery systems.

Fluorescence imaging in the second near-infrared window (NIR-II, 900-1700 nm) offers superior spatial resolution and penetration depth for in vivo visualization due to reduced tissue scattering and autofluorescence. However, the advancement of this modality is often constrained by the availability of organic fluorophores that combine straightforward synthesis, a large Stokes shift to minimize self-absorption, and high stability under physiological conditions. To address this challenge, we developed a simple yet effective molecular design strategy through the synergistic enhancement of π-conjugation via benzannulation and terminal donor engineering. This approach facilely yields a series of novel asymmetric xanthene dyes (NIR-820, NIR-842, and NIR-864) exhibiting tunable deep-NIR emission, enhanced Stokes shifts (∼54 nm), and remarkable photo/chemo-stability. The representative NIR-842 nanoparticles enabled high-contrast visualization of vasculature networks. Impressively, leveraging its extended emission tail beyond 1400 nm, high-fidelity real-time angiography with an outstanding signal-to-background ratio was achieved under 1400 nm long-pass filtration. This work not only presents a robust fluorophore for high-quality bioimaging, but also establishes a versatile molecular platform for the future development of high-performance NIR-II probes.

In drug development, multicomponent pharmaceutical materials have become useful tools for improving the properties and efficacy of a drug. In addition to the active drug, inclusion of a second component in the solid can provide stabilization or increase solubility of the pharmaceutical. Resveratrol, an antioxidant with many potential pharmacological effects, is limited by low aqueous solubility. Cocrystallization with 4-aminopyridine, an FDA approved medication used in the treatment of multiple sclerosis, was utilized and two ionic cocrystal phases were obtained. The two phases differ by stoichiometry, water inclusion, and proton transfer site on resveratrol. Reversible interconversion between both phases was achieved mechanochemically, a rare occurrence among multicomponent solids. This system demonstrates the first ionic crystalline forms of resveratrol, significantly enhanced solubility, and a rare example of a cocrystal system exhibiting different deprotonation sites at molecular locations with identical functional groups. The presence of anionic resveratrol in the solid could enhance its antioxidant efficacy compared to neutral resveratrol or other antioxidants. Furthermore, resveratrol has been previously reported to improve clinical markers in a mice model of multiple sclerosis, indicating this combination could offer a unique dual-therapeutic treatment.

Porous organosilica nanoparticles (PONs) are promising hybrid materials for a wide range of advanced applications, particularly in biomedical imaging, therapeutic delivery systems, and UV protection, due to their tunable organic-inorganic frameworks. However, integrating specific organic groups within PONs' structure, bearing function-enabling characteristics, remains challenging. Here we report the synthesis of novel PONs incorporating organic groups with UV-blocking and intrinsic anti-Stokes fluorescence capabilities, suitable for deep tissue imaging. The novel materials are prepared via co-condensation of a UV-absorbing triazine-based organosilane precursor with biphenyl-bridged silanes, yielding nanoparticles exhibiting broad UV protection (SPF ∼26) and strong anti-Stokes fluorescence upon continuous wave and femtosecond laser excitation above 700 nm. Spectroscopic analysis revealed distinct excitation mechanisms: hot-band absorption under continuous wave and two-photon excitation fluorescence (TPEF) under pulsed irradiation. The nanoparticles demonstrated high biocompatibility toward human skin cells and enabled effective two-photon imaging of glioblastoma cells, showing time-dependent cellular uptake. These multifunctional PONs combine UV shielding and advanced imaging capabilities, offering potential for applications in skin protection and nanomedicine, particularly for simultaneous imaging and therapeutic delivery.

Antifreeze peptides inhibit ice crystal growth and recrystallization, and are promising components of cryoprotective formulations for cell, tissue, and food preservation, as well as anti-icing surface coatings. However, the discovery of new antifreeze peptides has been hindered by their sequence diversity and the limited scalability of experimental screening. In this study, we identify novel antifreeze peptide candidates from a microbiome-derived sequence library using ensemble machine learning and molecular dynamics (MD) simulations. We developed an ensemble classifier composed of 10 adapter-tuned protein-language models and a random forest meta-learner. After training on a curated dataset of 73 766 sequences, we applied this ensemble to 56 008 amino acid sequences from an Arctic microbiome library to identify antifreeze peptide candidates. Structural prediction yields a diverse range of conformations for six selected candidates, including α-helices, coils, and combinations of both. To evaluate their functional relevance, atomistic MD simulations were conducted to assess conformational stability and solvent interactions under freezing conditions. One candidate shows persistent helicity, surface amphipathicity, and an organized hydration pattern consistent with structural signatures reported for ice-binding helices. These findings expand the known landscape of antifreeze peptides and highlight a scalable strategy for discovering functional peptides from complex biological sources.