Crystal Violet-Impregnated Slippery Surface to Prevent Bacterial Contamination of Surfaces

Biofilms which are self-organized communities can contaminate various infrastructural systems. Preventing bacterial adhesion on surfaces is more desirable than cleaning or disinfection of bacteria-contaminated surfaces. In this study, a 24 h bacterial adhesion test showed that "slippery surfaces" had increased resistance to bacterial contamination compared to polydimethylsiloxane and superhydrophobic surfaces. However, it did not completely inhibit bacterial attachment, indicating that it only retards surface contamination by bacteria. Hence, a strategy of killing bacteria with minimal bacterial adhesion was developed. A crystal violet-impregnated slippery (CVIS) surface with bactericidal and slippery features was produced through a simple dipping process. The CVIS surface had a very smooth and lubricated surface that was highly repellent to water and blood contamination. Bactericidal tests against Escherichia coli and Staphylococcus aureus showed that the CVIS surface exhibited bactericidal activity in dark and also showed significantly enhanced bactericidal activity (>3 log reduction in bacteria number) in white light.

Photobactericidal Activity of Dual Dyes Encapsulated in Silicone Enhanced by Silver Nanoparticles

Crystal violet (CV) and methylene blue (MB) dyes with silver (Ag) nanoparticles (NPs) were encapsulated into silicone to produce light-activated antimicrobial surfaces. Optical microscopy and X-ray photoelectron spectroscopy showed that CV and MB were diffused throughout the silicone samples and that Ag NPs were successfully encapsulated by the swell-encapsulation-shrink process. Antimicrobial tests on Staphylococcus aureus and Escherichia coli showed that CV/MB-encapsulated silicone samples have stronger photobactericidal activity than CV or MB samples and the addition of Ag NPs significantly enhanced the antimicrobial activity under white light. The number of viable bacteria decreased below the detection limit (below <103 CFU) on the silicone-incorporating CV/MB/Ag NPs within 3 h for S. aureus and within 5 h for E. coli. In leaching tests over 216 h, the amount of dye leaching from the samples was barely detectable (<0.02 ppm). These surfaces have a potential for use in healthcare settings to decrease hospital-associated infections.

The Anti-Biofouling Properties of Superhydrophobic Surfaces are Short-Lived

Superhydrophobic surfaces are present in nature on the leaves of many plant species. Water rolls on these surfaces, and the rolling motion picks up particles including bacteria and viruses. Man-made superhydrophobic surfaces have been made in an effort to reduce biofouling. We show here that the anti-biofouling property of a superhydrophobic surface is due to an entrapped air-bubble layer that reduces contact between the bacteria and the surface. Further, we showed that prolonged immersion of superhydrophobic surfaces in water led to loss of the bubble-layer and subsequent bacterial adhesion that unexpectedly exceeded that of the control materials. This behavior was not restricted to one particular type of material but was evident on different types of superhydrophobic surfaces. This work is important in that it suggests that superhydrophobic surfaces may actually encourage bacterial adhesion during longer term exposure.

Superhydrophobic and White Light-Activated Bactericidal Surface through a Simple Coating

Bacterial adhesion and proliferation on surfaces are a challenge in medical and industrial fields. Here, a simple one-step technique is reported to fabricate self-cleaning and bactericidal surfaces. White, blue, and violet paints were produced using titanium dioxide nanoparticles, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, crystal violet, toluidine Blue O, and ethanol solution. All of the painted surfaces showed superhydrophobicity in air, and even after hexadecane oil contamination, they retained water repellency and self-cleaning properties. In an assay of bacterial adhesion, significant reductions (>99.8%) in the number of adherent bacteria were observed for all the painted surfaces. In bactericidal tests, the painted surfaces not only demonstrated bactericidal activity against Staphylococcus aureus and Escherichia coli in the dark but also induced very potent photosensitization (>4.4 log reduction in the number of viable bacteria on the violet painted surface) under white light illumination. The technique that we developed here is general and can be used on a wide range of substrates such as paper, glass, polymers, and others.

Buoyancy increase and drag-reduction through a simple superhydrophobic coating

A superhydrophobic paint was fabricated using 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES), TiO₂ nanoparticles and ethanol. The paint has potential for aquatic application of a superhydrophobic coating as it induces increased buoyancy and drag reduction. Buoyance testing showed that the reduction of surface energy by superhydrophobic coating made it feasible that glass, a high density material, was supported by the surface tension of water. In a miniature boat sailing test, it was shown that the low energy surface treatment decreased the adhesion of water molecules to the surface of the boat resulting in a reduction of the drag force. Additionally, a robust superhydrophobic surface was fabricated through layer-by-layer coating using adhesive double side tape and the paint, and after a 100 cm abrasion test with sand paper, the surface still retained its water repellency, enhanced buoyancy and drag reduction.

Fine-mapping of 5q12.1-13.3 unveils new genetic contributors to caries

Caries is a multifactorial disease and little is still known about the host genetic factors influencing susceptibility. Our previous genome-wide linkage scan has identified the interval 5q12.1-5q13.3 as linked to low caries susceptibility in Filipino families. Here we fine-mapped this region in order to identify genetic contributors to caries susceptibility. Four hundred and seventy-seven subjects from 72 pedigrees with similar cultural and behavioral habits and limited access to dental care living in the Philippines were studied. DMFT scores and genotype data of 75 single-nucleotide polymorphisms were evaluated in the Filipino families with the Family-Based Association Test. For replication purposes, a total 1,467 independent subjects from five different populations were analyzed in a case-control format. In the Filipino cohort, statistically significant and borderline associations were found between low caries experience and four genes spanning 13 million base pairs (PART1, ZSWIM6, CCNB1, and BTF3). We were able to replicate these results in some of the populations studied. We detected PART1 and BTF3 expression in whole saliva, and the expression of BTF3 was associated with caries experience. Our results suggest BTF3 may have a functional role in protecting against caries.

Candidate gene strategy reveals ENAM mutations

Amelogenesis imperfecta (AI) is a genetically and phenotypically heterogeneous genetic disorder affecting tooth enamel without other non-oral syndromic conditions. Based on a review of the literature, the authors constructed a candidate-gene-based mutational analysis strategy. To test the strategy, they identified two Turkish families with hypoplastic enamel without any other non-oral syndromic phenotype. The authors analyzed all exons and exon/intron boundaries of the enamelin (ENAM) gene for family 1 and the DLX3 and ENAM genes for family 2, to identify the underlying genetic etiology. The analysis revealed 2 ENAM mutations (autosomal-dominant g.14917delT and autosomal-recessive g.13185-13186insAG mutations). A single T deletion in exon 10 is a novel deletional mutation (g.14917delT, c.2991delT), which is predicted to result in a frameshift with a premature termination codon (p.L998fsX1062). This result supports the use of a candidate-gene-based strategy to study the genetic basis for AI.

Axis inhibition protein 2 (AXIN2) polymorphisms and tooth agenesis

Tooth agenesis is a common congenital disorder that affects almost 20% of the world's population. A number of different genes have been shown to be associated with cases of tooth agenesis including AXIN2, IRF6, FGFR1, MSX1, PAX9, and TGFA. Of particular interest is AXIN2, which was linked to two families segregating oligodontia and colorectal cancer. We studied two collections of families affected with tooth agenesis and tested them for association with AXIN2. Significant association between tooth agenesis and AXIN2 was found (p=0.02) in cases with at least one missing incisor. Our work further supports a role of AXIN2 in human tooth agenesis and for the first time suggests AXIN2 is involved in sporadic forms of common incisor agenesis. Future studies should identify which specific tooth agenesis sub-phenotypes are consequence of AXIN2 genetic variations. A sub-set of these cases could have an increased susceptibility for colon cancer or other types of tumours and this knowledge would have significant clinical implications.

Enamel formation genes are associated with high caries experience in Turkish children

There is evidence for a genetic component in caries susceptibility, and studies in humans have suggested that variation in enamel formation genes and their interaction with Streptococcus mutans levels may contribute to caries. For the present study, we used DNA samples collected from 173 unrelated children from Istanbul: 91 children with 4 or more affected tooth surfaces and 82 caries-free children. Six single-nucleotide polymorphism markers were genotyped in selected candidate genes (ameloblastin, amelogenin, enamelin, tuftelin 1 and tuftelin interacting protein 11) that influence enamel formation. Allele and genotype frequencies were compared between groups with distinct caries experience. Regression analysis was used for the evaluation of individual gene effects, environmental effects and gene-environment interactions. Overrepresentation of the C allele of the amelogenin marker was seen in cases with dmft scores higher than 8 (p = 0.01) when compared to controls. Also, overrepresentation of the T allele of the ameloblastin marker was seen in cases with dmfs scores higher than 10 (p = 0.05) when compared to controls. In addition, the CT genotype of the tuftelin rs3790506 marker was overrepresented in cases with dmft scores higher than 5 (p = 0.05) and dmfs scores higher than 6 (p = 0.05) compared to controls. The best-fitting model showed that dmfs is increased when the following factors are present: (1) females and both the anterior and posterior teeth are affected simultaneously, (2) when the T allele of the tuftelin rs3790506 is involved, and (3) the C allele of the amelogenin rs17878486 is involved. Our study provides support that genes involved in enamel formation modify caries susceptibility in humans.