Jirun Sun

Composition drift during copolymerization can alter residual functionality and network composition, yet overall conversion measurements may conceal this evolution. Real‐time Raman spectroscopy with programmable irradiation separately quantifies methacrylate (MA) and styrenic (ST) vinyl conversion and tracks the residual MA/ST ratio during crosslinking photopolymerization. Raman‐derived compositions of uncured UDMA/TEG‐DVBE mixtures agree closely with prepared compositions and proton nuclear magnetic resonance measurements. Five equimolar MA/ST formulations are examined at irradiation intensities of 10–1000 mW cm ⁻² . TEGDMA/TEG‐DVBE and EBPADMA/TEG‐DVBE exhibit preferential early MA consumption, followed by persistent or largely compensated composition bias, respectively. UDMA/TEG‐DVBE maintains near‐feed composition across intensities, whereas Bis‐GMA/TEG‐DVBE exhibits similar behavior during rapid, high‐intensity curing. Substantial drift in Bis‐GMA/styrene indicates that intraspecies hydrogen bonding alone is insufficient for composition control. Irradiation intensity changes polymerization kinetics, but its effect on composition drift depends on formulation. Fourier transform infrared spectra indicate redistribution of hydrogen‐bonding environments upon mixing Bis‐GMA with TEG‐DVBE, without directly establishing specific interspecies associations or their persistence during curing. These findings identify hydrogen bonding as a possible contributor rather than an established controlling mechanism. Real‐time Raman spectroscopy reveals distinct residual‐composition trajectories that overall conversion alone cannot resolve and provides a framework for evaluating composition control in photocured networks.

Since the pioneering work of Dr

Acidogenic and aciduric bacteria acidify their local microenvironment through carbohydrate metabolism, contributing to pathological microenvironment acidification in diseases, including dental caries, infection, and inflammation. We present a mesoporous silica nanoparticle platform equipped with surface-bound, pH-responsive gatekeepers that remain sealed at physiological pH yet rapidly release a drug payload under acidic conditions. This system converts a broad-spectrum antimicrobial into a selectively activated antimicrobial system: release is suppressed under neutral conditions and triggered when bacteria generate acid. In a human oral microbiome model, the nanoparticles selectively eradicate acid-producing bacteria, with metabolic acidification directly activating their own killing, as evidenced by simultaneous single-cell-scale fluorescence imaging of pH and viability. Mechanistic studies using proton NMR and contact angle measurements show that the gating mechanism relies on synergistic molecular interactions and hydrophilicity–hydrophobicity transitions. This work establishes an on-site antimicrobial strategy triggered by metabolic acidification for targeting microbes with undesirable metabolic features, thus paving the way toward more controlled infection therapies.

We present a physics-based digital twin framework that predicts microstructure evolution in nanoparticle-filled polymer composites by coupling particle-scale Brownian dynamics with time-dependent rheology representative of processing and cure conditions. The model resolves stochastic Brownian diffusion, short-range van der Waals attraction, excluded-volume interactions, and probabilistic collision-driven irreversible sticking to simulate aggregation and kinetic arrest within statistically representative volume elements subject to periodic boundary conditions. Realistic filler loadings are enforced through mass balance, and ensemble-averaged descriptors, including number-average cluster size, nearest-neighbor distance distributions, pair correlation functions, and cluster-size distributions, which provide statistically converged measures of evolving morphology. To demonstrate transferability, the framework is validated against experimentally characterized nanocomposite systems spanning melt-processed and thermally cured polymers, where simulated nearest-neighbor spacing statistics agree quantitatively with image-derived measurements within experimental uncertainty. Parametric studies demonstrate that particle size and filler loading strongly govern aggregation kinetics and cluster morphology, while viscosity evolution primarily controls the rate of aggregation and the progressive suppression of particle mobility over the simulation window. The approach is computationally efficient, enabling simulations over micron-scale representative volumes containing hundreds to thousands of particles, and provides a foundation for microstructure-informed design of particle-reinforced polymer composites. Material-specific behavior is introduced exclusively through measurable physical inputs (particle properties, rheology history, and processing conditions), enabling the same digital twin architecture to be applied across distinct composite chemistries.

Background: Tooth root caries and periodontal tissue loss remain major challenges in elderly and periodontally compromised patients, while current restorative materials lack combined antibacterial and regenerative properties. Objective: The objective of this study was to develop a novel metformin-containing antibacterial composite for root cavity restorations to prevent recurrent caries and potentially promote periodontal tissue regeneration. Methods: Experimental composites contained 5% dimethylaminohexadecyl methacrylate (DMAHDM), varying metformin concentrations (2.5–15%), and glass fillers. Mechanical and antibacterial properties as well as cytocompatibility toward human periodontal ligament stem cells (hPDLSCs) were investigated. Results: The experimental composites achieved flexural strengths of 67.9 to 50.1 MPa (n = 6), significantly higher than (41.3 ± 3.4 MPa) of commercial control Vitremer (p < 0.05), while maintaining clinically acceptable elastic moduli of 3.7–3.1 GPa. Experimental composites achieved an 8-log reduction in Streptococcus mutans (S. mutans) biofilms and significantly reduced lactic acid production and metabolic activity compared to biofilms on commercial controls. The composite containing 15% metformin demonstrated acceptable cytocompatibility toward hPDLSCs under clinically relevant diluted conditions, matching commercial controls (p > 0.1). Conclusions: These findings suggest that this novel composite possesses potent antibacterial activity, acceptable cytocompatibility, and adequate mechanical properties, making it promising for multifunctional root caries restorations.

Secondary caries and biofilm accumulation remain major causes of failure in provisional crowns and restorations, highlighting the need for multifunctional resin coatings with antibacterial and remineralizing capabilities. This study aimed to develop a novel bioactive and antibacterial resin-based surface coating incorporating 10% dimethylaminododecyl methacrylate (DMADDM), 20% nanoparticles of amorphous calcium phosphate (NACP), and/or 20% calcium fluoride nanoparticles (nCaF₂) within a urethane dimethacrylate/triethylene glycol divinylbenzyl ether (UDMA/TEG-DVBE) matrix. Coatings were evaluated for degree of conversion (DC), flow, shear bond strength, brushing wear resistance (10,000 cycles), and calcium (Ca), phosphate (PO₄), and fluoride (F) ion release up to 70 days. All groups achieved clinically acceptable polymerization, with the lowest DC at 50%. NACP-containing coatings significantly increased shear bond strength to 18.3 ± 2.8 MPa, representing a ~170% increase compared with the experimental control (6.8 ± 2.1 MPa) and exceeding the ISO 10477 minimum threshold of 5 MPa. After brushing simulation, experimental coatings demonstrated low wear depth (0.93–1.19 µm), which was ~40% lower than the commercial control (1.85 ± 0.40 µm). Sustained ion release was achieved for 70 days, with 20% NACP-formula releasing 1.22 mmol/L Ca and 0.90 mmol/L PO₄, while the dual NACP–nCaF₂ formulation provided simultaneous Ca (0.62 mmol/L) and F (0.33 mmol/L) release. The developed coatings demonstrated promising physicochemical properties, bonding performance, wear resistance, and sustained remineralizing ion release, supporting their potential application as therapeutic surface coatings for provisional restorations.

The development of next-generation antimicrobial materials requires experimental platforms capable of resolving how microbes interact with their local microenvironment at high spatial and temporal resolution. However, conventional microbiological assays lack the ability to capture single-cell behavior and microscale physicochemical changes, limiting the evaluation of stimulus-responsive antimicrobial systems. Here, we present a three-dimensional (3D) hydrogel-based culture platform that overcomes these limitations by enabling single-cell monitoring of microbial dynamics within a confined and customizable microenvironment. A poly(acrylamide)-based hydrogel was used to encapsulate Streptococcus mutans, an oral cariogenic pathogen, and integrated with ratiometric imaging of the pH-sensitive probe C-SNARF-4 to simultaneously quantify bacterial viability and local pH at high resolution. As proof of concept, we evaluated the antimicrobial performance of a pH-responsive drug delivery system loaded with a conventional broad-spectrum agent. The hydrogel cultures supported robust S. mutans viability (≥80% at 1 h and 24 h) and metabolic activity, while enabling real-time, single-cell detection of metabolism-driven antimicrobial effects (e.g., carbohydrate fermentation-induced acidification), which are not discernible using conventional inhibition-zone assays. This platform establishes a versatile 3D biomaterial model for interrogating microbial behavior and metabolism within defined microenvironments and provides a powerful tool for developing and evaluating antimicrobial therapies as well as elucidating mechanisms that drive microbial communities from dysbiosis toward health.

Hydrogel materials and scaffolds have emerged as transformative tools in biological research by offering control and customization of cell viability, metabolism, and productivity. Their compatibility with 3D bioprinting and patterning technologies enables the precise and reproducible organization of living components, ushering in novel experimental paradigms across diverse disciplines. Although most 3D hydrogel research has emphasized mammalian cell applications, particularly in tissue engineering, there is a growing body of research applying these technologies to study, manipulate, and harness a variety of microorganisms, such as bacteria. This review surveys the latest advances in microbial hydrogel encapsulation, focusing on material selection and patterning methods designed to preserve microbial viability and function. We compare the distinct requirements and challenges of culturing microorganisms in hydrogels versus mammalian systems and highlight recent breakthroughs in bacterial bioprinting that are advancing microbiological research, leading to current and emerging applications in areas including oral health. By synthesizing current knowledge and identifying promising future directions, this review underscores the potential of microbial hydrogel culture as a versatile platform for investigating microbial communities, probing bacterial–material interactions, and engineering living materials with applications in human health and environmental systems.