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With the aging of the population, dental caries in the elderly has received increasing attention. A comprehensive study of the oral microbiome is required to understand its polymicrobial etiology. The results of previous studies are limited and remain controversial. In this study, subjects 60 years and older with and without caries were recruited. Unstimulated saliva and dental plaque were collected from each subject and the bacterial 16S rDNA was amplified using PCR and sequenced by Illumina MiSeq high-throughput sequencing. A total of 92 samples were collected from 24 caries patients and 22 healthy controls. Sequences clustered into 147,531 OTUs, representing 16 phyla, 29 classes, 49 orders, 79 families, 149 genera, and 305 species. All predominant phyla, including Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Actinobacteria, and Saccharibacteria, were largely consistent in different groups, but different relative abundances could be observed. The core microbiome was defined with 246 shared species among groups, which occupied 80.7% of all the species detected. Alpha diversity showed no significant differences in bacterial richness or diversity between caries patients and healthy controls, but distinction existed between samples collected from dental plaque and saliva. Beta diversity analysis was performed by PCoA and hierarchical clustering analysis, showing similar results that microorganisms vary between the two niches. The biomarkers of different groups were defined by LEfSe analysis to identify potential caries-related and health-related bacteria. The co-occurrence analysis of the predominant genera revealed significant interactions among oral microbiota and exhibited more complex and aggregated bacterial correlations in caries-free groups. Finally, the functional prediction of the microbiota present in oral samples was performed by PICRUSt, indicating vigorous microbial metabolism in the oral bacterial community. Our study provides thorough knowledge of the microbiological etiology of elderly individuals with caries and is expected to provide novel methods for its prevention and treatment.

The development of simple, rapid-response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual-emitting europium-organic framework (Eu-MOF), which is assembled from a purposely selected 2-aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched-on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu3+ emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn-on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu-MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05–10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l’Eclairage (CIE) chromaticity coordinate. The present Eu-MOF sensor featuring high sensitivity and reusability, self-calibration, simple fabrication and operation, and capability for real-time and in situ detection is expected to have practical applications in water analysis for industrial processes.

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Acquired immune deficiency syndrome (AIDS) is a severe communicable immune deficiency disease caused by the human immune deficiency virus (HIV). The analysis laboratory diagnosis of HIV infection is a crucial aspect of controlling AIDS. The p24 antigen, the HIV-1 capsid protein, is of considerable diagnostic interest because it is detectable several days earlier than host-generated HIV antibodies following HIV exposure. We present herein a new sandwich HIV p24 immunosensor based on directly electroplating an electrode surface with gold nanoparticles using chronoamperometry, which greatly increased the conductivity and reversibility of the electrode. Under optimum conditions, the electrochemical signal showed a linear relationship with the concentration of p24, ranging from 0.01 ng/mL to 100 ng/mL (R > 0.99), and the detection limit was 0.008 ng/mL. Compared with ELISA, this method increased the sensitivity by more than two orders of magnitude (the sensitivity of ELISA for p24 is about 1 ng/mL). This immunosensor may be broadly applied to clinical samples, being distinguished by its ease of use, mild reaction conditions, guaranteed reproducibility, and good anti-interference ability.