Coatings

Understanding the interfacial biological response of superhydrophobic surfaces is critical for their safe deployment in sanitary and clinical environments. This study investigates the substrate-driven cytocompatibility of superhydrophobic silica nanoparticle (SiO₂ NPs) coatings, functionally modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) or 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDTMS). To elucidate the synergistic influence of the coating chemistry and the underlying material, the fluorinated systems were deposited on an inert glass substrate and an active structural aluminum alloy (Al7075). Wettability characterization confirmed superhydrophobicity, yielding water contact angles (WCA) > 150° and water sliding angles (WSA) ≤ 10° for all coated surfaces. Biological evaluations using primary fibroblasts, encompassing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays (24 and 48 h) and hematoxylin and eosin (H&E) morphological staining, revealed a distinctly substrate-dependent cellular response. On glass substrates, PFDTMS coatings maintained a non-cytotoxic response, whereas PFDTES exhibited a time-dependent reduction in cell viability and adhesion, albeit remaining safely above the non-cytotoxicity threshold (>70%). Conversely, on the Al7075 alloy, both fluorinated coatings demonstrated high cell viability (>90%) and extensive cellular spreading, with PFDTES exhibiting a highly favorable early-stage interfacial interaction. These findings suggest that, within the evaluated model, the cytocompatibility of superhydrophobic treatments exhibits strong substrate dependence rather than being solely an intrinsic property of the functional coating. This comparative study provides experimental evidence for the strategic design and engineering of functionalized metallic interfaces in healthcare applications.

To address the trade-off among thermal conductivity, thermal stability, and flexibility of silicone rubber (SR) composites, a bioinspired dual-surface modification strategy was proposed to functionalize Ti₃AlC₂ MAX phase fillers with tannic acid (TA) and methyl triethoxysilane (MTES). TA was first self-assembled on the Ti₃AlC₂ surface to form an active adlayer, followed by MTES grafting to obtain Ti₃AlC₂@TA-MTES. The structure, morphology, and composition of the modified fillers were characterized by XRD, FTIR, XPS and SEM. The introduction of TA serves as a biomimetic intermediate platform rich in phenolic hydroxyl groups, providing abundant anchoring sites for subsequent MTES condensation. At 40 phr filler loading, the thermal conductivity of Ti₃AlC₂@TA-MTES/SR reached 0.76 W/(m·K), 55.1% higher than that of unmodified composites and 322% higher than that of pure SR. The composite with 30 phr modified filler exhibited excellent thermal stability (T10 = 512.1 °C, T50 = 613.4 °C) and enhanced mechanical properties. This work provides a feasible and scalable approach for fabricating flexible thermal management materials for high-integration electronic devices and flexible electronics.

Resin infiltration of root cementum requires optimal surface preparation; however, traditional protocols using hydrochloric acid raise some concerns about potential cementum degradation. In this in vitro study the physicochemical and morphological impact of 36% H₃PO₄ on root cementum compared to natural demineralisation was evaluated to establish a candidate tissue-preserving conditioning agent. Twelve extracted teeth—incisors with exposed cementum over gum recession level and fully impacted third molars were analysed using scanning electron microscopy (SEM) and Energy Dispersive Spectrometry (EDS) in etched and not-etched specimens. Orthophosphoric acid significantly reduced calcium and phosphorus content across all specimens while maintaining overall morphological integrity. Notably, the elemental response varied based on tooth exposure history. Incisors exhibited a statistically significant reduction in the Ca/P atomic ratio, indicating complex stoichiometric shifts and preferential calcium loss. Conversely, impacted third molars maintained a stable Ca/P ratio, suggesting proportional mineral dissolution in unexposed cementum. These findings indicate that natural demineralisation is insufficient for adequate surface modification and that orthophosphoric acid demineralizes root cementum without compromising its structural integrity. The magnitude and pattern of this response depend on the tissue’s prior exposure to the oral environment; thus, structural heterogeneity of cementum, though tailored protocols, are necessary.