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This study developed a novel antibacterial conjugate based on carbon nanohorns for peri-implantisis, an inflammatory disease around dental implants, which may result in failing implants by bone loss around them. The conjugate demonstrates much better photodurability than commonly used indocyanine green and a significant antibacterial effect under NIR illumination. [ABSTRACT FROM AUTHOR]

Food texture is a very important factor for elderly persons, children, and patients who have difficulty swallowing. Collagen and its hydrolysis product, gelatin, are used as ingredients in foods, dietary supplements, and medical materials. In this study, we extracted atelocollagen from nonedible porcine tissues, including ear, nose, and skin, and analyzed the biophysical properties of each tissue. Extracted whole auricle collagen (AEC) showed superior springiness, while only the skin region of auricle collagen (ASC) showed superior hardness, springiness, and brittleness. Body skin collagen showed high hardness but low springiness. In a shear stress test, ASC gels showed high shear strength, and their strains coincided with hardness in a textural examination, while nose and AEC showed low maximum strains. In viscosity, the auricular collagens showed higher viscosity regardless of the region of the ear. Fibril formation in collagen from each tissue and organ varied a great deal in width and morphology. We found that the same type of collagen had a unique texture and viscosity under physiological conditions depending on the tissue or organ of extraction. The results show that the collagen extracted from each organ has a unique texture and unique possibilities to serve as an ingredient in food or supplements. [ABSTRACT FROM AUTHOR]

Direct contact between bone and implant materials is required for dental implants. Titanium is used for the implant material owing to its mechanical and biological properties. The anodisation as the surface treatment was employed to enhance osteogenesis around titanium. Moreover, carbon nanohorn (CNH), a type of nanometer-sized carbon material, was reported to promote the bone formation. Thus, it is expected that if the surface of anodised Ti (AnTi) is modified with CNHs, Ti-bone contact would be enhanced. In this study, the Ti surface was modified with CNHs by electrophoresis and obtained anodised titanium coated with CNHs (CNH/AnTi). In vitro, CNH/AnTi attracted osteoblastic cells more than AnTi, thereby the proliferation of osteoblastic cell was enhanced by CNH/AnTi more than by AnTi. In vivo, at 7 and 28 days after implantation of CNH/AnTi or AnTi into the rat femur, more aggressive bone formation was observed on the surface of CNH/AnTi than on AnTi. More importantly, the area where newly formed bone tissue directly attached to CNH/AnTi was significantly larger than that for AnTi, suggesting that "contact osteogenesis" was accelerated on CNH/AnTi during the early post-implantation period. CNH/AnTi would be advantageous especially for the early stages of bone regeneration after surgery. [ABSTRACT FROM AUTHOR]

Geobacterales is a recently proposed order comprising members who originally belonged to the well-known family Geobacteraceae , which is a key group in terrestrial ecosystems involved in biogeochemical cycles and has been widely investigated in bioelectrochemistry and bioenergy fields. Previous studies have illustrated the taxonomic structure of most members in this group based on genomic phylogeny; however, several members are still in a pendent or chaotic taxonomic status owing to the lack of genome sequences. To address this issue, we performed this taxonomic reassignment using currently available genome sequences, along with the description of two novel paddy soil-isolated strains, designated Red51T and Red69T, which are phylogenetically located within this order. Phylogenomic analysis based on 120 ubiquitous single-copy proteins robustly separated the species Geobacter luticola from other known genera and placed the genus Oryzomonas (fam. Geobacteraceae) into the family ' Pseudopelobacteraceae '; thus, a novel genus Geomobilimonas is proposed, and the family ' Pseudopelobacteraceae ' was emended. Moreover, genomic comparisons with similarity indexes, including average amino acid identity (AAI), percentage of conserved protein (POCP), and average nucleotide identity (ANI), showed proper thresholds as genera boundaries in this order with values of 70%, 65%, and 74% for AAI, POCP, and ANI, respectively. Based on this, the three species Geobacter argillaceus , Geobacter pelophilus , and Geobacter chapellei should be three novel genera, for which the names Geomobilibacter , Geoanaerobacter , and Pelotalea are proposed, respectively. In addition, the two novel isolated strains phylogenetically belonged to the genus Geomonas , family Geobacteraceae , and shared genomic similarity values higher than those of genera boundaries, but lower than those of species boundaries with each other and their neighbors. Taken together with phenotypic and chemotaxonomic characteristics similar to other Geomonas species, these two strains, Red51T and Red69T, represent two novel species in the genus Geomonas , for which the names Geomonas azotofigens sp. nov. and Geomonas diazotrophica sp. nov. are proposed, respectively. [ABSTRACT FROM AUTHOR]

In paddy soil, bacteria from the family Geobacteraceae have been shown to strongly contribute to the biogeochemical cycle. However, no Geobacteraceae species with validly published names have been isolated from paddy soil. In this study, we isolated and characterized four novel ferric reducing bacteria in the family Geobacteraceae from the paddy soils of three different fields in Japan. The four strains, S43T, Red53T, S62T, and Red111T, were Gram-stain negative, strictly anaerobic, chemoheterotrophic, and motile with peritrichous flagella. Phylogenetic studies based on 16S rRNA gene sequences, five concatenated housekeeping genes (fusA , rpoB , recA , nifD , and gyrB) and 92 concatenated core genes revealed that the four strains belong to the family Geobacteraceae and are most closely related to Geobacter bemidjiensis BemT (97.4–98.2%, 16S rRNA gene sequence similarities) and Geobacter bremensis Dfr1T (97.1–98.0%). Genomic analysis with average nucleotide identity (ANI) and digital DNA–DNA hybridization (GGDC) calculations clearly distinguished the four isolated strains from other species of the family Geobacteraceae and indicated that strains S43T, Red53T, S62T, and Red111T represent independent species, with values below the thresholds for species delineation. Chemotaxonomic characteristics, including major fatty acid and whole cell protein profiles, showed differences among the isolates and their closest relatives, which were consistent with the results of DNA fingerprints and physiological characterization. Additionally, each of the four isolates shared a low 16S rRNA gene sequence similarity (92.4%) and average amino acid identity (AAI) with the type strain of the type species Geobacter metallireducens. Overall, strains S43T, Red53T, S62T, and Red111T represent four novel species, which we propose to classify in a novel genus of the family Geobacteraceae , and the names Geomonas oryzae gen. nov., sp. nov. (type strain S43T), Geomonas edaphica sp. nov. (type strain Red53T), Geomonas ferrireducens sp. nov. (type strain S62T), and Geomonas terrae sp. nov. (type strain Red111T) are proposed. Based on phylogenetic and genomic analyses, we also propose the reclassification of Geobacter bremensis as Geomonas bremensis comb. nov., Geobacter pelophilus as Geomonas pelophila comb. nov., and Geobacter bemidjiensis as Geomonas bemidjiensis comb. nov. [ABSTRACT FROM AUTHOR]

The cell structure and interface between cultured cells and a multiwalled carbon nanotube (MWCNT)-coated sponge (MWCNT-coated sponge) were observed by transmission electron microscopy (TEM). Moreover, the atomic structure of MWCNTs that entered the cells was also examined by means of high-resolution TEM (HRTEM). MWCNTs were observed in the cytoplasm, and a few MWCNTs were recognized in the cell nuclei. Those MWCNTs maintained their structure there. Subcellular organelles did not appear to be different from those on the collagen sponge despite the cellular uptake of MWCNTs. [ABSTRACT FROM AUTHOR]

The cell adhesion in a multiwalled carbon nanotube‐coated collagen sponge (MWCNT‐coated sponge) was investigated. Immediately after seeding, the cells adhered to the inner surface of the MWCNT‐coated sponge and a significantly larger number of cells were observed there than for a pure collagen sponge used as control. On the MWCNT‐coated sponge, the cells appeared favorable adhesion and spread in the early stages in the center part of the sponge which cells rarely attached without MWCNT‐coating. It was suggested that the physical structure of MWCNTs was effective for initial adhesion of cells from the result of serum‐free culture. MWCNT‐coating makes the material a suitable three‐dimensional scaffold for cell culturing, as opposed to other scaffold systems where such an effect is not seen. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study introduced the usefulness of LYVE-1 immunoreactivity for identification of lymphatic vessels in decalcified tissues, and demonstrated the fine distribution and organization of these vessels in mouse gingiva. Design: After confirming the specificity of anti-mouse LYVE-1, frozen sections of mouse decalcified gingiva were immunostained with the antibody. Results: The LYVE-1-positive lymphatic vessels were clearly found in the connective tissue under the gingival epithelium; these vessels appeared to pass through the lamina propria of the gingiva toward the alveolar crest and run along the external surface of the alveolar bone. The lymphatic vessels were sparse and apart from the oral gingival and sulcular epithelia, while they were dense adjacent to the junctional epithelium. Conclusions: The dense network of the lymphatic vessels adjacent to the junctional epithelium, which is apparently exposed to foreign antigens, may act as an efficient drainage pathway of the excessive interstitial fluid and immune cells, and play an active role in the immune defense of the gingiva. The present study also revealed the absence of lymphatic connection between gingiva and periodontal ligament. [Copyright &y& Elsevier]

Bacteria in the family Geobacteraceae have been proven to fill important niches in a diversity of anaerobic environments and global biogeochemical processes. Here, three bacterial strains in this family, designated Red875T, Red259T, and Red421T were isolated from river sediment and paddy soils in Japan. All of them are Gram-staining-negative, strictly anaerobic, motile, flagellum-harboring cells that form red colonies on agar plates and are capable of utilizing Fe(III)-NTA, Fe(III) citrate, ferrihydrite, MnO 2 , fumarate, and nitrate as electron acceptors with acetate, propionate, pyruvate, and glucose as electron donors. Phylogenetic analysis based on the 16S rRNA gene and 92 concatenated core proteins sequences revealed that strains Red259T and Red421T clustered with the type strains of Geomonas species, whereas strain Red875T formed an independent lineage within the family Geobacteraceae. Genome comparison based on  average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values clearly distinguished these three strains from other Geobacteraceae members, with lower values than the thresholds for species delineation. Moreover, strain Red875T also shared low average amino acid identity (AAI) and percentage of conserved proteins (POCP) values with the type species of the family Geobacteraceae. Based on these physiological, chemotaxonomic, and phylogenetic distinctions, we propose that strain Red875T (=NBRC 114290T = MCCC 1K04407T) represents a novel genus in the family Geobacteraceae , namely, Geomesophilobacter sediminis gen. nov., sp. nov., and strains Red259T (=NBRC 114288T = MCCC 1K05016T) and Red421T (=NBRC 114289T = MCCC 1K06216T) represent two novel independent species in the genus Geomonas , namely, Geomonas propionica sp. nov. and Geomonas anaerohicana sp. nov., respectively. [ABSTRACT FROM AUTHOR]

• PDT using silver nanoclusters/rose bengal nanocomposite and white LED eliminates oral bacterial cells. • Photoexcited silver nanoclusters/rose bengal nanocomposite generates 1O 2 and Ag+ ions. • Silver nanoclusters/rose bengal nanocomposite does not cause adverse effects in mammalian cells. Antimicrobial photodynamic therapy (a-PDT) is a promising anti-infective technique for generation of singlet oxygen (1O 2) to target dental disease. However, conventional organic photosensitizers have problems for clinical use in terms of cytotoxicity, quenching of a-PDT activity by self-dimerization, and the lack of long-term antibacterial effect. We herein propose silver nanoclusters/rose bengal nanocomposite (AgNCs/RB) as a novel photosensitizer with two primary antibacterial effects: (1) 1O 2 generation by irradiated RB and (2) Ag+ ion release from AgNCs. AgNCs/RB irradiated with white light-emitting diode (LED) for a short irradiation time of 1 min significantly decreased the bacterial turbidity of Streptococcus mutans , Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans (P < 0.05). In SEM, TEM and LIVE/DEAD staining images, photoexcited AgNCs/RB reduced S. mutans colonization, destroyed the cell membrane, and increased the number of dead cells. The antibacterial efficiency of photoexcited AgNCs/RB was greater than that of AgNCs or RB alone (P < 0.05), suggesting a synergistic effect of 1O 2 and Ag+ ions from photoexcited AgNCs/RB. By contrast, photoexcited AgNCs/RB did not affect WST-8 and LDH activities and morphology of NIH3T3 mammalian cells, indicating low cytotoxicity. Interestingly, the antibacterial activity of AgNCs/RB on S. mutans was maintained even after the cessation of LED irradiation, indicating a long-term antibacterial effect due to released Ag+ ions. The present AgNCs/RB photosensitizers provide effective synergistic antibacterial effects for dental a-PDT via 1O 2 and Ag+ ions coupled with low cytotoxicity. [ABSTRACT FROM AUTHOR]

Bacteria of the family Geobacteraceae are particularly common and deeply involved in many biogeochemical processes in terrestrial and freshwater environments. As part of a study to understand biogeochemical cycling in freshwater sediments, three iron-reducing isolates, designated as Red96T, Red100T, and Red88T, were isolated from the soils of two paddy fields and pond sediment located in Japan. The cells were Gram-negative, strictly anaerobic, rod-shaped, motile, and red-pigmented on agar plates. Growth of these three strains was coupled to the reduction of Fe(III)-NTA, Fe(III) citrate, and ferrihydrite with malate, methanol, pyruvate, and various organic acids and sugars serving as alternate electron donors. Phylogenetic analysis based on the housekeeping genes (16S rRNA gene, gyrB, rpoB, nifD, fusA, and recA) and 92 concatenated core genes indicated that all the isolates constituted a coherent cluster within the family Geobacteraceae. Genomic analyses, including average nucleotide identity and DNA–DNA hybridization, clearly differentiated the strains Red96T, Red100T, and Red88T from other species in the family Geobacteraceae, with values below the thresholds for species delineation. Along with the genomic comparison, the chemotaxonomic features further helped distinguish the three isolates from each other. In addition, the lower values of average amino acid identity and percentage of conserved protein, as well as biochemical differences with their relatives, indicated that the three strains represented a novel genus in the family Geobacteraceae. Hence, we concluded that strains Red96T, Red100T, and Red88T represented three novel species of a novel genus in the family Geobacteraceae, for which the names Oryzomonas japonicum gen. nov., sp. nov., Oryzomonas sagensis sp. nov., and Oryzomonas ruber sp. nov. are proposed, with type strains Red96T (= NBRC 114286T = MCCC 1K04376T), Red100T (= NBRC 114287T = MCCC 1K04377T), and Red88T (= MCCC 1K03694T = JCM 33033T), respectively. [ABSTRACT FROM AUTHOR]

Forty-eight Acidobacteriota strains were isolated from soils and sediments in Japan. Among them, six representative strains, designated W79 T , W786 T , Red222 T , Red802 T , Red803 T , and Red804 T , were subjected to the taxonomic classification. These six strains are Gram-stain-negative, non-spore-forming, rod-shaped, and facultative anaerobic bacterium that can reduce ferric iron. Phylogenetic and phylogenomic trees based on 16S rRNA genes and multiple single-copy gene sequences showed that strains Red222 T , Red802 T , Red803 T , and Red804 T formed a cluster with the type strains of Geothrix species, but strains W79 T and W786 T created an independent cluster from any other type strains. The former four strains shared 97.95-99.08% similarities of 16S rRNA gene sequence with the type strains of the genus Geothrix , whereas the latter two strains 94.86-95.49% similarities. The average amino acid identity of strains W79 T and W786 T were <63 % to any other type strains, which were below the genus delineation thresholds. Moreover, colonies of these two strains were white, while those of the other four isolated strains were reddish-yellow as well as the type strain Geothrix fermentans H-5 T . Although the known type strains of Geothrix species have been reported to be non-motile, five strains (W79 T , W786 T , Red222 T , Red803 T , and Red804 T ) except for strain Red802 T displayed motility. Furthermore, multiple genomic, phylogenetic, and phenotypic features supported the discrimination between these isolated strains. Based on the study evidence, we propose these six isolates as novel members within the Acidobacteriota / Holophagae / Holophagales / Holophagaceae , comprising two novel species of a novel genus, Mesoterricola silvestris gen. nov., sp. nov., and Mesoterricola sediminis sp. nov., and four novel species of the genus Geothrix: Geothrix oryzae sp. nov., Geothrix edaphica sp. nov., Geothrix rubra sp. nov., and Geothrix limicola sp. nov.

Three bacterial strains (Red232 T , Red267 T and Red630 T ) were isolated from paddy soils sampled in Japan. Cells of these strains were Gram-stain-negative, facultative anaerobic, long rod-shaped with monotrichous flagella or pilus-like structures for motility, and formed red colonies on agar plates. Phylogenetic trees based on 16S rRNA gene and multiple single-copy gene sequences showed that the three strains formed a cluster with the type strains of Anaeromyxobacter species, independent from any other strain genera. Similarity values of the 16S rRNA gene sequences and genomes among the three isolated strains and the type strain of Anaeromyxobacter , Anaeromyxobacter dehalogenans 2CP-1 T , were 95.4-97.4% for 16S rRNA gene sequence, 75.3-79.5% for average nucleotide identity, 19.6-21.7% for digital DNA-DNA hybridization and 64.1-72.6% for average amino acid identity, all of which are below the species delineation thresholds. Nitrogenase genes were observed in the genomes of the three novel strains, but not in A. dehalogenans 2CP-1 T . Moreover, multiple genomic, physiological and chemotaxonomic features supported the discrimination between these three strains. Based on the evidence in this study, the three isolates represent three novel independent species for which the following names are proposed: Anaeromyxobacter oryzae sp. nov., Anaeromyxobacter diazotrophicus sp. nov. and Anaeromyxobacter paludicola sp. nov. The type strains are Red232 T (=NBRC 114074 T =MCCC 1K03954 T ), Red267 T (=NBRC 114075 T =MCCC 1K04211 T ), and Red630 T (=NBRC 114076 T =MCCC 1K03957 T ), respectively.

A photochemical reaction mediated by light-activated molecules (photosensitizers) in photodynamic therapy (PDT) causes molecular oxygen to be converted into highly reactive oxygen species (ROS) that are beneficial for cancer therapy. As the active oxygen consumer and the primary regulator of apoptosis, mitochondria are known as an important target for optimizing PDT outcomes. However, most of the clinically used photosensitizers exhibited a poor tumor accumulation profile as well as lack of mitochondria targeting ability. Therefore, by applying a nanocarrier platform, mitochondria-specific delivery of photosensitizers can be materialized. The present research develops an effective mitochondria-targeting liposome-based nanocarrier system (MITO-Porter) encapsulating a π-extended porphyrin-type photosensitizer (rTPA), which results in a significant in vivo antitumor activity. A single PDT treatment of the rTPA-MITO-Porter resulted in a dramatic tumor inhibition against both human and murine tumors that had been xenografted in a mouse model. Furthermore, depolarization of the mitochondrial membrane was observed, implying the damage of the mitochondrial membrane due to the photochemical reaction that occurred specifically in the mitochondria of tumor cells. The findings presented herein serve to verify the significance of the mitochondria-targeted nanocarrier system for advancing the in vivo PDT effectivity in cancer therapy regardless of tumor type., Competing Interests: The authors declare no conflict of interest in this work., (This journal is © The Royal Society of Chemistry.)

Three bacterial strains, designated Red330 T , Red736 T and Red745 T , were isolated from forest and paddy soils in Japan. Strains Red330 T , Red736 T and Red745 T are flagella-harbouring and strictly anaerobic bacteria forming red colonies. A 16S rRNA gene sequence-based phylogenetic tree showed that all three strains were located in a cluster, including the type strains of Geomonas species, which were recently separated from the genus Geobacter within the family Geobacteraceae . Similarities of the 16S rRNA gene sequences among the three strains and Geomonas oryzae S43 T , the type species of the genus Geomonas , were 96.3-98.5 %. The genome-related indexes, average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity, among the three strains and G. oryza e S43 T were 74.7-86.8 %, 21.2-33.3 % and 70.4-89.8 %, respectively, which were lower than the species delineation thresholds. Regarding the phylogenetic relationships based on genome sequences, the three strains clustered with the type strains of Geomonas species, which were independent from the type strains of Geobacter species. The distinguishableness of the three isolated strains was supported by physiological and chemotaxonomic properties, with the profile of availability of electron donors and cellular fatty acids composition being particularly different among them. Based on genetic, phylogenetic and phenotypic properties, the three isolates represent three novel independent species in the genus Geomonas , for which the names Geomonas silvestris sp. nov., Geomonas paludis sp. nov. and Geomonas limicola sp. nov. are proposed. The type strains are Red330 T (=NBRC 114028 T =MCCC 1K03949 T ), Red736 T (=NBRC 114029 T =MCCC 1K03950 T ) and Red745 T (=NBRC 114030 T =MCCC 1K03951 T ), respectively.

A marine strain, designated KK4 T , was isolated from the surface of a starfish, Patiria pectinifera , which was collected from seawater off the coast of Hokkaido, Japan. Strain KK4 T is a Gram-stain-negative, non-spore-forming, rod-shaped, aerobic bacterium that forms yellow-pigmented colonies. A phylogenetic relationship analysis, based on 16S rRNA gene sequences, revealed that strain KK4 T was closely related to Ulvibacter marinus IMCC12008 T , Ulvibacter antarcticus IMCC3101 T and Ulvibacter litoralis KMM 3912 T , with similarities of 96.9, 95.8 and 95.6 %, respectively, but low sequence similarities (<94 %) among other genera in the family Flavobacteriaceae . Genomic similarities between strain KK4 T and the three Ulvibacter type strains based on average nucleotide identity and digital DNA-DNA hybridization values were lower than the species delineation thresholds. Moreover, phylogenetic tree based on genome sequences showed that strain KK4 T was clustered with U. marinus IMCC12008 T and formed a branch independent from the cluster including type species of the genera Ulvibacter , Marixanthomonas , Marinirhabdus , Aureitalea and Aequorivita . Amino acid identity values between strain KK4 T / U. marinus IMCC12008 T and the neighbour type species/strains were 61.9-68.2% and 61.5-67.4 %, which were lower than the genus delineation threshold, implying the novel genus status of strain KK4 T . Strain KK4 T growth occurred at pH 6.0-9.0, 4-30 °C and in NaCl concentrations of 0.5-5.0 %, and optimally at pH 7.0, 25 °C and 3.0 %, respectively. Unlike Ulvibacter strains, strain KK4 T could assimilate glucose, mannose, galactose and acetate. The major quinone and fatty acids were menaquinone-6 and iso-C 15 : 0 (27.5 %), iso-C 15 : 1 G (22.5 %) and iso-C 17 : 0 3-OH (12.8 %), respectively. Based on genetic, phylogenetic and phenotypic properties, strain KK4 T represents a novel species of the genus Patiriisocius , for which the name Patiriisocius marinistellae gen. nov., sp. nov. is proposed. The type strain is KK4 T (=JCM 33344 T =KCTC 72225 T ). In addition, based on the current data, Ulvibacter marinus should be reclassified as Patiriisocius marinus comb. nov.

Antimicrobial photodynamic therapy (aPDT) has beneficial effects in dental treatment. We applied captopril-protected gold (Au 25 (Capt) 18 ) clusters as a novel photosensitizer for aPDT. Photoexcited Au clusters under light irradiation generated singlet oxygen ( 1 O 2 ). Accordingly, the antimicrobial and cytotoxic effects of Au 25 (Capt) 18 clusters under dental blue light-emitting diode (LED) irradiation were evaluated. 1 O 2 generation of Au 25 (Capt) 18 clusters under blue LED irradiation (420-460 nm) was detected by a methotrexate (MTX) probe. The antimicrobial effects of photoexcited Au clusters (0, 5, 50, and 500 μg/mL) on oral bacterial cells, such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans , and Porphyromonas gingivalis , were assessed by morphological observations and bacterial growth experiments. Cytotoxicity testing of Au clusters and blue LED irradiation was then performed against NIH3T3 and MC3T3-E1 cells. In addition, the biological performance of Au clusters (500 μg/mL) was compared to an organic dye photosensitizer, methylene blue (MB; 10 and 100 μg/mL). We confirmed the 1 O 2 generation ability of Au 25 (Capt) 18 clusters through the fluorescence spectra of oxidized MTX. Successful application of photoexcited Au clusters to aPDT was demonstrated by dose-dependent decreases in the turbidity of oral bacterial cells. Morphological observation revealed that application of Au clusters stimulated destruction of bacterial cell walls and inhibited biofilm formation. Aggregation of Au clusters around bacterial cells was fluorescently observed. However, photoexcited Au clusters did not negatively affect the adhesion, spreading, and proliferation of mammalian cells, particularly at lower doses. In addition, application of Au clusters demonstrated significantly better cytocompatibility compared to MB. We found that a combination of Au 25 (Capt) 18 clusters and blue LED irradiation exhibited good antimicrobial effects through 1 O 2 generation and biosafe characteristics, which is desirable for aPDT in dentistry., Competing Interests: Disclosure The authors report no conflicts of interest in this work.