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A new covert luminescent anticounterfeiting (AC) technology was developed by employing combinatorial chemistry and concentration-dependent stimulus-responsive luminescent patterns. Oxygen-sensitive materials are carefully tailed to be inkjet printable and to form luminescent color inks. The inks are placed in the tanks of a jet printer. The printed luminescent patterns exhibited multilevel and highly secured AC features. Unlike conventional luminescent AC technology that solely relies on luminescent molecules/nanoparticles, the new technique utilizes the following features to fight counterfeiting: (1) the combination of luminescent oxygen-sensitive probes (OSPs) and the oxygen-permeable matrix (OPM), (2) the unique nonlinear oxygen-responsive behavior, (3) the local oxygen concentration, and (4) a luminescence lifetime reading device. The virtually unlimited number of codes is mainly due to the following features: (a) an almost endless number of combinations of OSPs and OPMs and (b) the nonlinearity of the Stern–Volmer plots that describe quenching of luminescence by oxygen. This combinatorial chemistry strategy makes it very difficult for counterfeiters to find the right composition even when the chemical composition of the luminescent molecules/nanoparticles was known. Information encrypted via this new methodology exhibits extremely high security, as counterfeiters need to identify all (not part of them) the following security measures: (1) the right combination of OSPs and OPMs, (2) the right chemical stimulus (here oxygen), (3) the proper oxygen concentration, and (4) the correct luminescence lifetime values.

The fact that the lifetime of photoluminescence is often difficult to access because of the weakness of the emission signals, seriously limits the possibility to gain local bioimaging information in time‐resolved luminescence probing. We aim to provide a solution to this problem by creating a general photophysical strategy based on the use of molecular probes designed for single‐luminophore dual thermally activated delayed fluorescence (TADF). The structural and conformational design makes the dual TADF strong in both diluted solution and in an aggregated state, thereby reducing sensitivity to oxygen quenching and enabling a unique dual‐channel time‐resolved imaging capability. As the two TADF signals show mutual complementarity during probing, a dual‐channel means that lifetime mapping is established to reduce the time‐resolved imaging distortion by 30–40 %. Consequently, the leading intracellular local imaging information is serialized and integrated, which allows comparison to any single time‐resolved signal, and leads to a significant improvement of the probing capacity.

Dental caries is the most common disease in the human mouth. Streptococcus mutans is the primary cariogenic bacteria. Propolis is a nontoxic natural product with a strong inhibitory effect on oral cariogenic bacteria. The polyphenol-rich extract from propolis inhibit S. mutans growth and biofilm formation, as well as the genes involved in virulence and adherence, through the inhibition of glucosyltransferases. However, because the chemical composition of propolis is highly variable and complex, the mechanism of its antimicrobial action and the active compound are controversial and not completely understood. Caffeic acid phenethyl ester (CAPE) is abundant in the polyphenolic compounds from propolis, and it has many pharmacological effects. In this study, we investigated the antibacterial effects of CAPE on common oral cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus, Actinomyces viscosus and Lactobacillus acidophilus) and its effects on the biofilm-forming and cariogenic abilities of S. mutans. CAPE shows remarkable antimicrobial activity against cariogenic bacteria. Moreover, CAPE also inhibits the formation of S. mutans biofilms and its metabolic activity in mature biofilms. Furthermore, CAPE can inhibit the key virulence factors of S. mutans associated with cariogenicity, including acid production, acid tolerance and its ability to produce extracellular polysaccharides without affecting bacterial viability at subinhibitory levels. In conclusion, CAPE appears to be a new agent with anticariogenic potential, not only via inhibition of the growth of cariogenic bacteria.

BackgroundDental caries is a major worldwide oral disease afflicting a large proportion of children. As an important host factor of caries susceptibility, saliva plays a significant role in the occurrence and development of caries. The aim of the present study was to characterize the healthy and cariogenic salivary proteome and determine the changes in salivary protein expression of children with varying degrees of active caries, also to establish salivary proteome profiles with a potential therapeutic use against dental caries.MethodsIn this study, unstimulated saliva samples were collected from 30 children (age 10–12 years) with no dental caries (NDC, n = 10), low dental caries (LDC, n = 10), and high dental caries (HDC, n = 10). Salivary proteins were extracted, reduced, alkylated, trypsin digested and labeled with isobaric tags for relative and absolute quantitation, and then they were analyzed with GO annotation, biological pathway analysis, hierarchical clustering analysis, and protein–protein interaction analysis. Targeted verifications were then performed using multiple reaction monitoring mass spectrometry.ResultsA total of 244 differentially expressed proteins annotated with GO annotation in biological processes, cellular component and molecular function were identified in comparisons among children with varying degrees of active caries. A number of caries-related proteins as well as pathways were identified in this study. As compared with caries-free children, the most significantly enriched pathways involved by the up-regulated proteins in LDC and HDC were the ubiquitin mediated proteolysis pathway and African trypanosomiasis pathway, respectively. Subsequently, we selected 53 target proteins with differential expression in different comparisons, including mucin 7, mucin 5B, histatin 1, cystatin S and cystatin SN, basic salivary proline rich protein 2, for further verification using MRM assays. Protein–protein interaction analysis of these proteins revealed complex protein interaction networks, indicating synergistic action of salivary proteins in caries resistance or cariogenicity.ConclusionsOverall, our results afford new insight into the salivary proteome of children with dental caries. These findings might have bright prospect in future in developing novel biomimetic peptides with preventive and therapeutic benefits for childhood caries.Electronic supplementary materialThe online version of this article (10.1186/s12967-018-1388-8) contains supplementary material, which is available to authorized users.