Amplified electrochemical antibiotic aptasensing based on electrochemically deposited AuNPs coordinated with PEI-functionalized Fe-based metal-organic framework.

A facile and versatile competitive electrochemical aptasensor for tobramycin (TOB) detection is described using electrochemical-deposited AuNPs coordinated with PEI-functionalized Fe-based metal-organic framework (AuNPs/P-MOF) as signal-amplification platform and a DNA probe labeled with methylene blue (MB) at the 3'-end (MB-Probe) as a signal producer. First, F-Probe (short complementary DNA strands of both the aptamer and the MB-Probe label with a sulfhydryl group at the 5'-end) was immobilized on the AuNPs/P-MOF modified electrode as detection probes, which competed with TOB in binding to the aptamer. TOB-aptamer binding resulted in F-Probe remaining unhybridized on the electrode surface, so that a significant current response was generated by hybridizing with MB-Probe instead. The developed strategy showed favorable repeatability, with a relative standard deviation (RSD) of 4.3% computed over five independent assays, and high stability, with only 6.8% degradation after 15 days of storage. Under optimal conditions, the proposed aptamer strategy exhibited a linear detection range from 100 pM to 500 nM with a limit of detection (LOD) of 56 pM (S/N = 3). The electrochemical aptasensor demonstrated remarkable selectivity, and its feasibility for accurate and quantitative detection of TOB in milk samples was confirmed (RSD < 4.5%). Due to its simple design, easy operation, and high sensitivity and selectivity, the proposed method could expect to detect other antibiotics by replacing the aptamers. In summary, this study provides a simple and effective new strategy for electrochemical aptasening based on MOF-based sensing interface. Scheme illustration of label-free competitive electrochemical aptamer-based detection of tobramycin based on electrochemically deposited AuNPs coordinated with PEI-functionalized Fe-based metal-organic framework as signal-amplification platform.

Influences of pH and Iron Concentration on the Salivary Microbiome in Individual Humans with and without Caries.

This study aimed to identify the differences in the oral microbial communities in saliva from patients with and without caries by performing sequencing with the Illumina MiSeq platform, as well as to further assess their relationships with environmental factors (salivary pH and iron concentration). Forty-three volunteers were selected, including 21 subjects with and 22 without caries, from one village in Gansu, China. Based on 966,255 trimmed sequences and clustering at the 97% similarity level, 1,303 species-level operational taxonomic units were generated. The sequencing data for the two groups revealed that (i) particular distribution patterns (synergistic effects or competition) existed in the subjects with and without caries at both the genus and species levels and (ii) both the salivary pH and iron concentration had significant influences on the microbial community structure. IMPORTANCE: The significant influences of the oral environment observed in this study increase the current understanding of the salivary microbiome in caries. These results will be useful for expanding research directions and for improving disease diagnosis, prognosis, and therapy.

[Microbial Community Structure on the Root Surface of Patients with Periodontitis.]

OBJECTIVES: To study the microbial community structure on the root surface of patients with periodontitis. METHODS: Bacterial plaque and tissues from the root neck (RN group),root middle (RM group) and root tine (RT group) of six teeth with mobility 3 in one patient with periodontitis were sampled.The V3V4 region of 16S rRNA was sequenced on the Illumina MiSeq platform.The microbial community structure was analyzed by Mothur,Qiime and SPSS software. RESULTS: The principal component analysis (PCoA) results indicated that the RM samples had a similar microbial community structure as that of the RT samples,which was significant different from that of the RN samples.Thirteen phyla were detected in the three groups of samples,which included 7 dominant phyla.29 dominant genera were detected in 184 genera.The abundance of Bacteroidetes_[G-6] and Peptostre ptococcaceae_[XI][G-4] had a positive correlation with the depth of the collection site of samples (P<0.05),while the abundance of Prevotella,Selenomonas,Corynebacterium and Olsenella had a negative correlation with the depth of the collection site of samples (P<0.05). CONCLUSIONS: There is region-specificity of microbial community structure on the root surface of patients with periodontitis.

[Study on Microbial Diversity of Peri-implantitis Subgingival by High-throughput Sequencing].

OBJECTIVE: To study microbial diversity of peri-implantitis subgingival with high-throughput sequencing, and investigate microbiological etiology of peri-implantitis. METHODS: Subgingival plaques were sampled from the patients with peri-implantitis (D group) and non-peri-implantitis subjects (N group). The microbiological diversity of the subgingival plaques was detected by sequencing V4 region of 16S rRNA with Illumina Miseq platform. The diversity of the community structure was analyzed using Mothur software. RESULTS: A total of 156 507 gene sequences were detected in nine samples and 4 402 operational taxonomic units (OTUs) were found. Selenomonas, Pseudomonas, and Fusobacterium were dominant bacteria in D group, while Fusobacterium, Veillonella and Streptococcus were dominant bacteria in N group. Differences between peri-implantitis and non-peri-implantitis bacterial communities were observed at all phylogenetic levels by LEfSe, which was also found in PcoA test. CONCLUSION: The occurrence of peri-implantitis is not only related to periodontitis pathogenic microbe, but also related with the changes of oral microbial community structure. Treponema, Herbaspirillum, Butyricimonas and Phaeobacte may be closely related to the occurrence and development of peri-implantitis.

Relationship between Gingival Crevicular Fluid Microbiota and Cytokine Profile in Periodontal Host Homeostasis.

As potential biomarkers in periodontitis, microbiome, and cytokines have recently been extensively investigated, but combined analyses of the variations between the microbial structure and cytokine composition are rare. The present study aimed to investigate whether there are differences in the combined profile of microbiome and cytokines in individuals with or without periodontitis. The microbiome and cytokine composition in gingival crevicular fluid (GCF) from 16 patients and 15 controls from Jishi Shan (Gansu, China) were analyzed using 454 pyrosequencing and RayBio Quantibody Arrays. The results showed that a higher co-occurrence of genera in periodontitis group compared with the healthy group, as evaluated by Schoener's abundance-based co-occurrence index. C-reactive protein (CRP) was significantly (P < 0.05) higher in the GCF of the periodontitis group while interleukin (IL)-8 was significantly (P < 0.01) higher in the GCF of the healthy group. The Mantel test revealed a significant concordance between cytokines and microbiota, in the healthy group (Mantel statistic r = 0.36, P ≤ 0.05) but not in the periodontitis group (Mantel statistic r = 0.013, P = 0.434). The results were further confirmed by the Procrustes test. Matrix metalloproteinase (MMP)-9, osteoactivin, IL-8, and macrophage inflammatory protein (MIP)-1a were significantly associated with bacterial composition at the phylum, class, order, family, and genus levels. CRP was also associated with bacterial composition at the species level. In conclusion, alterations in the polymicrobial community structure leads to disruption in the healthy correlation between cytokines and microbiomes. This dysbiosis between the microbiota and the immune response could be one of the major etiological mechanisms underlying periodontitis.