Zinc hybrid polyester barrier membrane accelerates guided tissue regeneration.

Barrier membranes play a pivotal role in the success of guided periodontal tissue regeneration. The biodegradable barriers predominantly used in clinical practice often lack sufficient barrier strength, antibacterial properties, and bioactivity, frequently leading to suboptimal regeneration outcomes. Although with advantages in mechanical strength, biodegradability and plasticity, bioinert aliphatic polyesters as barrier materials are usually polymerized via toxic catalysts, hard to be functionalized and lack of antibacterial properties. To address these challenges, we propose a new concept that controlled release of bioactive substance on the whole degradation course can give a bioinert aliphatic polyester bioactivity. Thus, a Zn-based catalytic system for polycondensation of dicarboxylic acids and diols is created to prepare zinc covalent hybrid polyester (PBS/ZnO). The atomically-dispersed Zn2+ ions entering main chain of polyester molecules endow PBS/ZnO barrier with antibacterial properties, barrier strength, excellent biocompatibility and histocompatibility. Further studies reveal that relying on long-term controlled release of Zn2+ ions, the PBS/ZnO membrane greatly expedites osteogenetic effect in guided tissue regeneration (GTR) by enhancing the mitochondrial function of macrophages to induce M2 polarization. These findings show a novel preparation strategy of bioactive polyester biomaterials based on long term controlled release of bioactive substance that integrates catalysis, material structures and function customization.

A polyhexamethylene biguanide-assembly assisted strategy of dentin bonding greatly promotes bonding effects and caries treatment.

Structural degeneration of a hybrid layer composed of a demineralized dentin matrix (DDM) and adhesive causes unsatisfactory functional outcomes in terms of bonding repair and caries treatment and is accompanied by high prevalence of secondary caries. Clinically, defects in the hybrid layer from insufficient adhesive infiltration, bacterial load from retained infected-dentin, and bacterial attack from the oral cavity are the main threats to degeneration. Currently, there is no strategy to simultaneously address adhesive penetration and bacterial infection. Herein, based on the core role of the strongly-polar hydrated DDM interface in dentin bonding, an interface-reconstructed bonding strategy assisted by electrostatic assembly of broad-spectrum germicidal polyhexamethylene biguanide (PHMB) is proposed that kills two birds with one stone. PHMB is absorbed onto the anionic 3D DDM forming a PHMB/DDM complex. The surface potential of the DDM increases by about 100 mV, the anion content decreases by 20%, and the interface water content decreases by nearly 40%. All of these changes contribute to the penetration of the adhesive, thereby improving the bonding strength and durability. After thermal cycling aging, the bonding strength of the PHMB group was 1.45-1.65 times that of the control group. In terms of antibacterial properties, PHMB treatment not only has a bacterial-killing ability due to the already formed biofilm but also significantly reduces the adhesion of bacteria, thereby delaying the occurrence of secondary caries. In summary, PHMB treatment reconstructed the DDM interface, resulting in a defect-low and inherent antibacterial hybrid layer that improves the bonding effect, treatment of caries and even prevention of secondary caries.

Correction: A polyhexamethylene biguanide-assembly assisted strategy of dentin bonding greatly promotes bonding effects and caries treatment.

Correction for 'A polyhexamethylene biguanide-assembly assisted strategy of dentin bonding greatly promotes bonding effects and caries treatment' by Chang Shu et al., J. Mater. Chem. B, 2023, 11, 10908-10922, https://doi.org/10.1039/D3TB02083E.

Click-based injectable bioactive PEG-hydrogels guide rapid craniomaxillofacial bone regeneration by the spatiotemporal delivery of rhBMP-2.

Craniomaxillofacial bone defects result in physical and psychological dual injuries making the promotion or acceleration of bone regeneration imperative. In this work, a fully biodegradable hydrogel is facilely prepared via thiol-ene "click" reactions under human physiological conditions using multifunctional poly(ethylene glycol) (PEG) derivatives as precursors. This hydrogel shows excellent biological compatibility, enough mechanical strength, a low swelling rate and an appropriate degradation rate. Rat bone marrow mesenchymal stem cells (rBMSCs) can survive and proliferate on/in the PEG hydrogel and differentiate into osteogenic cells. The PEG hydrogel can also effectively load rhBMP-2 through the above "click" reaction. Under the physical barrier of the chemically crosslinked hydrogel network, the spatiotemporal release of rhBMP-2 effectively promotes the proliferation and osteogenic differentiation of rBMSCs at a loading concentration of 1 µg ml-1. Finally, based on a rat calvarial critical-size defect model, the rhBMP-2 immobilized hydrogel loaded with rBMSCs basically accomplishes the repair and regeneration within 4 weeks featured by remarkably enhanced osteogenesis and angiogenesis. The click-based injectable bioactive PEG hydrogel developed in the present study is a new type of bone substitute with great expectations in future clinical applications.

Preparation and biological evaluations of a collagen-like hierarchical Ti surface with superior osteogenic capabilities.

The construction of multiscale Ti surfaces of high osteogenic ability has always attracted significant attention in the fields of oral implantology and implantable biomaterials. However, to date, the absence of a solid understanding of the correlation between the multiscale surface structure and the biological properties is the main obstacle in the development of these multiscale implants. In this study, a series of novel multiscale Ti surfaces were prepared via a three-step subtractive method. Moreover, based on the grayscale analysis of SEM images, we developed multiscale surface topography analysis methods. The typical topography characteristics at each scale of a multiscale complex surface can be analyzed according to the corresponding magnified SEM images. Thus, the evolution rule of the surface topography from a simple surface to multiscale complex surfaces can be mathematically described. Based on this, the correlation between multiscale surface structures and the corresponding biological properties was established. For the multiscale surface of superior osteogenic capacity, strict inherent regularity was found among the structures at multiple scales (i.e., multiscale order), that is, there was a balance between the construction of the 3D collagen-like network nanostructure and the preservation of the typical topographical features of the pre-existing macro- and micro-structures of the classic micro-roughened surface. Moreover, it was further found that the multiscale-ordered hierarchical Ti surface structure could modulate ROS production and enhance macrophage M2 polarization to create an osteogenesis-favorable immuno-inflammatory microenvironment and synergistically exhibit superior biological capability. Consequently, an optimized collagen-like hierarchical surface with superior osteogenic abilities was achieved.

A study of the fluorescence characteristics of common cariogenic microorganisms.

OBJECTIVE: To explore the fluorescence characteristics of common cariogenic bacteria: Streptococcus mutans, S. sanguis, Actinomyces viscosus, Prevotella intermedia, Lactobacillus acidophilus, and Candida albicans. METHODS: The bacteria were cultured on brain heart infusion (BHI) agar and BHI blood agar, and bacterial colonies were collected for further amplification in liquid medium. Bacterial suspensions in physiological saline were equally divided into three parts for bacteria counting, fluorescence spectrometry detection, and fluorescence microscope examination. RESULTS: The optimal excitation wavelength of the bacteria was 350 nm; their characteristic fluorescence peak position was at 436 ± 4 nm. There was a significant linear correlation between fluorescence intensity and bacterial concentration. The mean optical density (MOD) of S. mutans and L. acidophilus cultivated in BHI blood was significantly higher than that cultivated in BHI agar (110 ± 10 vs. 57 ± 20; 94 ± 16 vs. 31 ± 12, respectively, P < 0.05). The MOD of S. sanguis, A. viscosus, and P. intermedia cultivated in BHI blood agar was higher than that cultivated in BHI agar (37 ± 12 vs. 36 ± 11; 43 ± 17 vs. 38 ± 6; 86 ± 21 vs. 72 ± 8, respectively, P > 0.05); the opposite was observed for C. albicans. CONCLUSION: At 350 nm excitation wavelength, 436 ± 4 nm is an indicator for detecting six cariogenic bacteria. The fluorescence energy, Q, is a valuable index reflecting bacterial concentration under fluorescence spectrometry detection. Exogenous fluorescence groups have greater influence on fluorescence intensity and little influence on fluorescence peak position detection.

[Fourier transform infrared spectroscopy in detection of breast cancer].

Breast cancer is the most common cancer in women. Later diagnosis of the disease is the leading cause of poor prognosis. Fourier-transform infrared (FTIR) spectroscopy is a novel approach to provide information about the molecular components and metabolic conditions of human tissue; therefore it can detect the early changes caused by cancer cells prior to histological manifestation. FTIR-based diagnosis is rapid, simple and label free, which meets the requirements of an automated and patient-friendly technique. The current article gives an overview of the experimental techniques, data analysis methods and spectral signatures of breast cancer in FTIR-based diagnosis, summarizes the present challenges by focusing on the history of FTIR spectroscopy in breast cancer since 1990s, and highlights some investigations that give a perspective of FTIR-based diagnosis.

Identification of a novel benzimidazole that inhibits bacterial biofilm formation in a broad-spectrum manner.

Bacterial biofilm formation causes significant industrial economic loss and high morbidity and mortality in medical settings. Biofilms are defined as multicellular communities of bacteria encased in a matrix of protective extracellular polymers. Because biofilms have a high tolerance for treatment with antimicrobials, protect bacteria from immune defense, and resist clearance with standard sanitation protocols, it is critical to develop new approaches to prevent biofilm formation. Here, a novel benzimidazole molecule, named antibiofilm compound 1 (ABC-1), identified in a small-molecule screen, was found to prevent bacterial biofilm formation in multiple Gram-negative and Gram-positive bacterial pathogens, including Pseudomonas aeruginosa and Staphylococcus aureus, on a variety of different surface types. Importantly, ABC-1 itself does not inhibit the growth of bacteria, and it is effective at nanomolar concentrations. Also, coating a polystyrene surface with ABC-1 reduces biofilm formation. These data suggest ABC-1 is a new chemical scaffold for the development of antibiofilm compounds.