Current biomaterials are effective at replacing biological structures, but are limited by infections and long-term material failures. In this study, we examined the molecular mechanisms of Radio Frequency Glow Discharge Treatments (RFGDT) in mediating disinfection of biomaterial surfaces and concurrently promoting cell attachment and proliferation. Dental biomaterials were subjected to RFGDT and viability of oral microbial species namely Streptococcus mutants (SM), Streptococcus gordonii (SG), Moraxella catarrhalis (MC), and Porphyromonas gingivalis (PG) were assessed. Cell attachment and survival of a pre-odontoblast cell line, MDPC-23, was examined. Finally, mechanistic investigations into redox generation and biological signaling were investigated. Dental biomaterials induced reactive ozygen species (ROS) following dose-dependent RFGDT based on their compositions. RFGDT reduced microbial viability in the catalase-negative (SM and SG) species more effectively than catalase-positive (MC and PG) species. Cell adhesion assays noted improved MDPC-23 attachment and survival. Pretreatments with N-acetylcysteine (NAC) and catalase abrogated these responses. Immunoassays noted redox-induced downstream expression of a laminin receptor, RPSA, following RFGDT. Thus, RFGDT-induced redox mediates antimicrobial and improved cell responses such as adhesion and proliferation. These observations together provide a mechanistic rationale for the clinical utility of RFGDT with dental biomaterials for regenerative clinical applications.

Current biomaterials effectively replace biological structures but are limited by infections and long-term material failures. This study examined the molecular mechanisms of radio frequency glow discharge treatments (RFGDT) in mediating the disinfection of biomaterial surfaces and concurrently promoting cell attachment and proliferation. Dental biomaterials were subjected to RFGDT, and viability of oral microbial species, namely Streptococcus mutants (SM), Streptococcus gordonii (SG), Moraxella catarrhalis (MC), and Porphyromonas gingivalis (PG), were assessed. Cell attachment and survival of a pre-odontoblast cell line, MDPC-23, was examined. Finally, mechanistic investigations into redox generation and biological signaling were investigated. Based on their compositions, dental biomaterials induced reactive oxygen species (ROS) following dose-dependent RFGDT. Reduced microbial viability was evident following RFGDT in the catalase-negative (SM and SG) species more prominently than catalase-positive (MC and PG) species. Cell adhesion assays noted improved MDPC-23 attachment and survival. Pretreatments with N-acetylcysteine (NAC) and catalase abrogated these responses. Immunoassays noted redox-induced downstream expression of a laminin receptor, Ribosomal Protein SA, following RFGDT. Thus, RFGDT-induced redox mediates antimicrobial and improves cell responses such as adhesion and proliferation. These observations together provide a mechanistic rationale for the clinical utility of RFGDT with dental biomaterials for regenerative clinical applications.

Infectious diseases of the oral cavity generated by bacteria and fungi remain one of the major problems confronting clinical dentistry.1 Significant advances in treating and preventing these diseases have been discussed over the past decades. Titanium (Ti) dental implants have been used successfully as replacements to untreatable or missing teeth.1 Dental biofilm can cause bacterial infection around dental implants leading to the risk of implant failure due to the loss of the supporting bone.1 In peri-implantitis cases, the traditional clinical management presents with more challenges as disrupting implants surfaces should be avoided, which limits the ability of the mechanical removal of infectious biofilm that happens to protect harmful bacteria. Healthy peri-implant soft and hard tissues are especially crucial to the long-lasting healthy function of any dental restorations supported by implants.1Sul et al2 have found that the most critical factor for optimal re-osseointegration is good surface chemistry. Although bone can re-osseointegrate around a previously infected implant,3 the surfaces of the implant need to be mechanically cleaned to remove any infectious biofilm. The bone also has to be free of pathogenic bacteria. As a way to avoid surface disturbance while decontaminating infected implants, the use of laser has been recently utilized with positive outcomes.4 The procedure involves the use of a laser with specified settings in combination with other traditional techniques to ensure effective antibacterial protocol. This protocol may have an improved antibacterial effect. However, it has not yet replaced the need for traditional mechanical removal of biofilm.4 New and effective treatment and prevention strategies are still needed to control this too costly disease.At the microbiology level, many approaches for achieving better mechanical removal of biofilm have been investigated.5 Advances in biofilm adhesion and surface science have fostered research in biomaterials, the biochemistry of small molecules, and altering gene expression striving toward the same goal of weakening biofilm attachment.6,7One of the relatively new modalities for fighting oral biofilms is photodynamic therapy (PDT). Photodynamic therapy is an established chemotherapy treatment for localized tumors that have been introduced recently to the dental field as a bactericidal strategy.8 Photodynamic therapy involves the application and retention of an applied photosensitizing agent (dye) in targeted tissues, followed by light/laser illumination with specific settings including energy density and illumination time that can activate the selected dye.9,10 This light activation will create free radicals that lead to disruption of cancer cells in various ways affecting only the targeted cells and offering minimal disruption of healthy adjacent tissue. This affinity of the photosensitizing agent to cell walls was found to be applicable to bacteria in dental biofilms as these dyes selectively bind to the bacteria in biofilms attached closely to Ti surfaces.9,11 The level of penetration of the photosensitizing agent to the targeted tissue is an essential factor for effective treatment. Hence, different photosensitizing agents are suggested based on the type of cancer tissue. Even though this may be less relevant for oral biofilm, yet it offers a variety of agents that can potentially be chosen based on the antibacterial effect on oral biofilms. One attractive feature of PDT as an antibacterial treatment is the use of harmless visible light of the correct wavelength to excite the photosensitizer. However, PDT creates the reactive oxygen species generated from the excited state of the dye that can chemically destroy many of the organic cell components by reactive oxidation. Thus, PDT, in addition to being antimicrobial, may also be destructive of the organic matrix components of the biofilm.Since the electrostatic charge of any administered chemical drug may affect its ability to bind with cell walls, the charge of selected photosensitizer is heavily studied in the PDT literature. Polysaccharide (PSs) or exopolysaccharides (EPS) are known to be anionic (negatively charged), which increases bonding forces to bacteria in biofilms, allowing stronger resistance against antibacterial drugs.12Photosensitizers based on the cationic (positively charged) can exhibit high, broad-spectrum antibacterial activity regardless of current drug-resistance status; this is also applicable as an antifungal activity.13 Due to its effectiveness on biofilm, PDT use in dental settings has been increasingly investigated.8,14,15 A commonly used broad-spectrum photosensitizer is methylene blue (MB). Methylene blue is a cationic and hydrophobic dye that has demonstrated a high killing rate when applied as a photosensitizer to a variety of subgingival bacteria using short illumination time (60 seconds) with moderate energy density (21.2 J/cm2), which resulted in prevention of the re-colonization of subgingival lesions by pathogenic microorganisms.16Harris et al11 have indicated that phenothiazinium-based photosensitizers, including MB, show selectivity for uptake into a tumor and microbial cells. This result appears to be based on electrostatic interactions between the positive charge generally carried by the MB molecules and the negative charge found on the outer surfaces of target cells. They found that this type of photosensitizer can inactivate several intracellular targets such as proteins and enzymes of the outer membranes/envelopes of the cells. Moreover, it can modify lipids and/or lipopolysaccharides.17 They explained that the hydrophobicity of MB allows interaction with cell wall lipids. Methylene blue leads to peroxidation that causes hydroperoxide formation, which increases ion permeability ending with Na+ and K+ leakage; these effects usually lead to cell lysis and death, making this type of photosensitizers antimicrobial agents without the added illumination.George et al18 have suggested that electrostatic interactions and self-promoted uptake pathways mediate the uptake of cationic photosensitizer in contrast to anionic photosensitizer where the uptake can be affected by the nature of bacteria.The effect of PDT on the attachment of cancer cells was studied in the field of photophysics and cancer medicine due to the concern of increasing risks of metastasis breaking from the treated tumor mass caused by attachment changes. In the dental field, few studies have focused on the effects of PDT on bioadhesion.19,20 In the Soares et al19 study, they demonstrated the ability of PDT, toluidine blue O (TBO) mediated photosensitizer, with relatively high energy density to inhibit both the viability and adhesion of Candida albicans to buccal epithelial cells in vitro.19 Mang et al20 have investigated the effect of PDT on the adhesion of gram-negative bacteria with promising results.Of the many types of oral flora, one of the most studied bacteria is S mutans. Its sensitivity to PDT is well documented.21 It is a gram-positive, facultative anaerobic bacterium that plays a significant role in tooth decay. Studies on the use of PDT on S mutans biofilm are increasing due to its availability, and the relative ease of application.22 Bacterial adhesion is particularly crucial for oral bacteria. Meurman et al23 have reported that cell wall projections mediate S mutans adhesion to apatite crystals; these electron-dense structures form near the division site of this bacterium and are characteristically well-formed in S mutans of the strain used in this study. The reasons above made the S mutans attractive choice to use for this study.Generally, removing or weakening biofilm attachment is favorable, whether the weakening is achieved by detaching the biofilm from a substratum or by damaging the attachments within the cohesive layers of the bacteria in a biofilm. Although detached cancer cells is a possible shortcoming of PDT in cancer treatment, it may present as an advantage in the case of oral biofilm.The present study aimed to evaluate the capability of PDT to produce changes in the bioadhesion of S mutans biofilms to biomaterial surface. The attachment strength was determined by calculating the shear stress needed to remove biofilms of S mutans from commercially pure Ti. The ability of PDT to kill the bacteria of 3 various levels of maturity was also examined. This work tested the hypothesis that PDT induces oxidative embrittlement and fragmentation of plaque/biofilm matrix biopolymers, allowing more effective removal via hydrodynamic (rinsing) forces.Two groups of commercially pure Ti samples were prepared to test (1) attachment strength and (2) antibacterial effect separately. For the attachment strength tests, large rectangular pieces size of 50 × 20 mm were used. Smaller pieces with a size of 5 × 10 mm for the antibacterial capacity test. All pieces were autoclaved and sterilized using radio-frequency glow discharge to obtain a clean and sterile surface.Streptococcus mutans bacterial strain ATCC 27351 was used for this investigation. Bacteria were routinely grown in general-purpose Brain Heart Infusion (BHI) broth (Difco; Fisher Scientific, Co, LLC) at 37°C. Bacteria were transferred every 48 hours into fresh BHI for the entire study duration. Titanium pieces with the bacterial solution were incubated in an orbital shaker incubator (Lab-Line) at a continuous moderate speed of 125 RPM at 37°C.After 48 hours of incubation in the shaker, the test pieces were transferred into another sterile test tubes filled with fresh BHI and mixed with 1% sucrose. The Ti pieces were then kept in the shaker incubator under the same conditions for up to 4 days. After biofilm growth, each Ti piece was then placed flat in a Petri dish and washed by adding 1 mL phosphate-buffered saline (PBS) and pipetting out the PBS. All pieces were grouped into a PDT treatment group, a control group, and a group to test the dark toxicity of photosensitizers.The thicknesses of the biofilms varied between 0.190 and 0.524 mm, as measured using a calibrated microscope stage.Each Ti piece was treated separately with a low concentration of MB (0.01%) in aqueous solution in a dark room at room temperature for 6 minutes. After incubation, excess MB was removed. The test pieces were then illuminated; excitation wavelength ranged from 660 to 675 nm laser (Periowave, Ondine Biomedical, Inc). The laser source (diode laser) was held at a distance of 4 cm to create a treatment diameter of 2.5 cm for about 3-minute exposure in total. Titanium pieces in the control group were kept in the dark for the same time.Alamar Blue (AB), a vital dye, was used in this study for measuring the viability of treated biofilm.24After completing the PDT treatment, each piece was placed in BHI, and then provided with 10% AB in a darkened room then incubated for 9–20 hours to assess the viability and concentration of bacteria in the biofilm. Monitoring was done by recording absorbance at 570 and 600 nm.The protocol used required culturing biofilm bacteria in agar plates and 100 μL of BHI + biofilm suspension diluted to 10%. Agar plates were then incubated for 2–4 days to be observed for colony forming unit (CFU) counting.25Multiple attenuated internal reflection infrared (MAIR-IR) spectroscopy is a sensitive surface characterization technique that allows the operator to characterize thin films of material on a face of a Germanium prism using infrared. Infrared spectra characterize the sample by revealing the functional groups of the material via their covalent bond resonances as the beam passes through the sample film.26 This technique was used in this study to detect the change in biofilm characterization after PDT and the nature of detached and remaining material.The germanium prisms used for this analysis were prepared with the same steps of Ti sample preparation. Biofilms were grown on the prisms in the same manner as they were on the Ti samples.It should be mentioned that both bioadhesion and vitality tests were done on the following: (1) PDT treated samples (MB + laser), (2) MB only incubated control samples (no laser), and (3) Biofilm control (no MB, no laser).Jet impingement is a precise yet simple engineering technique for measuring the shear stress required to remove layers from a solid substratum. In this study, jet impingement was used to accurately calculate the adhesion strength required to detached biofilm layers from the Ti substrata. By using a known flow rate of the fluid through a needle with a known nozzle diameter and a known distance between the surface and the nozzle exit, a standard detachment strength vs circle-size of the removed material are plotted in graphs to acquire shear stress.27 Two different flow rates were used for this experiment 10 mL/s and 20 mL/s (Figure 1).For future references in this study, 2 separate areas of detachment will be distinguished: (1) central circles of the detached biofilm from Ti base (visually clean circles), and (2) the halos surrounding within-biofilm-matrix (partially cleaned circles where the film had not been entirely detached from the solid substratum (Figure 2).Biofilms on Ti samples (treated and controls) were dyed with crystal violet and incubated for 8–10 minutes to aid in the visualization of the biofilms under light microscopy.Each piece was securely fixed flat under the nozzle opening. Distilled water then impinged for 30 seconds at each biofilm. Titanium samples were air-dried. Diameters of circles of detachment were measured by light microscopy. The resultant detached diameters of (central circles) and (halos) were measured and used to calculate shear stresses (Figure 2).Photos of biofilms specimens were taken by reflected light microscopy (ZEISS), scanning electron microscopy, and stereo light microscopy (Olympus).Independent samples t test was applied using (SPSS) program at (P < .05). At least 8–10 samples in each group were used for the viability test (total of above 100 samples). For the bioadhesion test, measurements were calculated for 43 samples. Each experiment was repeated 3 times on 3 different occasions. Pilot work was done before designing the final experiment. T test showed a significant difference in shear stress for biofilm at all maturity levels except at the peak stationary phase (48 hours). For the younger and older biofilms, P values ranged from .00 to .025, whereas insignificant P values ranged from .13 to .98. for the stationary peak phase of 48 hours.The spectra obtained from treated specimens showed that shear stress of approximately 10 dynes/cm2 was able to remove substantially more material from treated biofilm compared with control. These results were represented in MAIR-IR by showing lower amounts of retained protein, carbohydrate, and lipid components (smaller peaks) in the PDT treated biofilm than for the nontreated controls (more massive peaks). Moreover, a comparison of the spectrum peak heights indicated significantly more removal of PSs extracellular polymers than the removal of the protein-dominated microbes themselves. Characteristic spectra are shown in Figures 3 and 4.To test the effect on various ages of biofilms, 3 different stages of maturity of bacteria starting the biofilm formation were used in this study; younger biofilms started with 24 and 48 hours (1 + 2 days old of 50% each), older biofilm starting at 48 and 72 hours (2 + 3 days old 50% each), and at stationary peak growth of 48-hour-old biofilm.Vitality was measured using AB.28 Dark toxicity of MB (MB with no laser) to S mutans was observed. Photodynamic therapy mediated by MB showed antibacterial capacity on all stages of biofilms; however, the results were variable. Biofilms started with older (2 and 3 days old) showed the most sensitivity for PDT antibacterial capacity. This was parallel to the bioadhesion results (Figure 5).Photodynamic therapy also showed a significant bactericidal effect as well on younger biofilm.Biofilms started with bacteria cultured for precisely 48 hours (stationary phase): This group of biofilms was the most resistant to PDT treatment, both the antibacterial and the adhesion (Figure 6).The effects of water jets were noticeably different between PDT-treated biofilms and the control samples in all groups. Results confirmed the difference in shear stress values between the treated biofilms and the control samples. Moreover, the jet penetrated more in-depth into the treated samples confirmed visually. The smallest detachment was observed at 48 hours. For this group, the statistical difference in shear stress was not significant. However, the penetration depth was visually significant (Figures 7 and 8). These results support the hypothesis of the ability of MB-mediated PDT to weaken biofilms of S mutans.Interestingly, thicker biofilms demonstrated more attachment strength only in the control group; the treated biofilms were almost all weakened even in the thickest areas.The removal of various biofilms cultures of bacteria from the Ti substrata (centrally detached areas) required mean shear stress of 143.3 dyne/cm2 for control samples and 89 dynes/cm2 for treated samples. Only 67.2 and 51 dyne/cm2 were required to remove the biofilm from the halos for the control and treated samples, respectively (Table).The PDT treatment was primarily effective in weakening the attachment of the extracellular slime components of these biofilms.This study aimed to focus on the effect of PDT on biofilm adhesion. The killing effect of PDT on various bacteria is well documented in the literature.29 Nevertheless, the bactericidal effect was also studied in a parallel manner to test the existing relation between the strength of biofilm adhesion and the activity level of the living organisms. The PDT and adhesion tests were performed on biofilms of different stages of maturity as a way to create variable factors closer to the natural settings. It also gives more validity to the claim that suggests a possible relationship between the activity level and attachment strength of bacteria in a biofilm. The results of this work confirmed the susceptibility of biofilm made from S mutans on Ti to PDT as a bactericidal and embittering method of the film. Methylene blue was selected for this work for its wide range of bactericidal effect. Methylene blue has also been tested on S mutans, showing promising results despite its concentration.30Other photosensitizing agents can be used on biofilms; Zanin et al21 also showed that using erythrosine on S mutans was 5–10 times more effective on killing than when using MB. They also indicated that PDT, for this bacterium, kills mainly by damaging the outer membrane.During the pilot testing for this work, it was decided to add sucrose to the growing biofilms as it allowed the needed visualization of the biofilm, especially by the increased "fluff," which was mainly layers of PSs. The pilot testing on S mutans bacterial showed that 48 hours was the stationary peak growth and activity of the used strain.Methylene blue showed a high bactericidal effect on S mutans as well, even when used alone, confirming dark toxicity. Particularly since these bacterial cultures (provided with sucrose) had a low pH of 4.2, which is within the range for optimal MB effects/uptake.30Gad et al31 have demonstrated that lethal photosensitization can be reduced by the presence of EPS explained by the EPS "trapping" of the photosensitizer on the outside of the cell membrane, which is thought to be one of the critical sites of PDT-mediated damage. However, they observed that the absolute uptake of photosensitizer by the cells was 10 times higher when a cationic photosensitizer was used compared with an anionic counterpart.It should be mentioned that MB can inactivate bacterial cells when it engages actively to the outer membrane; it can eventually impair the cell function by accumulating in the outer wall when it is highly concentrated within the EPS.31This can explain the high level of dark toxicity in this work demonstrated by MB, showing a significant killing ability when used alone. These results are in agreement with previous work that showing even inactivated MB alone kills microbes by membrane destruction.32In this work, shear stress measurements indicated that the force required to remove the biofilm from the Ti substratum was higher than the force needed to separate and remove the bacteria within the EPS matrix of each biofilm. This means that detaching the biofilm within its bulk is less difficult than removing the biofilm from the Ti substratum. The most durable adhesion of the biofilms tested here was the adhesion that occurred between the bacteria and the solid surface. Results could be different if a substratum of different material, perhaps one with "easy release" properties, were used.33This observation also supports that the MB induced PDT effect likely involves breaking down the slime layer's cohesion rather than reversing the active bacterial adhesion to the underlying substrata.The results of PDT bactericidal effect and adhesion strength were reasonably parallel in this work; the stronger the bioadhesion of biofilms, the lower the bactericidal effect of PDT. Part of these results corresponded with the results of Wood et al,28 who found that "young" biofilms of S mutans were more resistant to PDT than "older" biofilms due to more superficial penetration of the dye in the former. However, these results do not correlate with results of Zanin et al21 who found that younger biofilms of S mutans were more sensitive to PDT than older ones when treated with TBO. The vital difference between Zanin et al21 and the present study is that for this current study, the age variation was among the cultures that started the biofilms and not in the age of biofilms.It has been documented in the literature that one of the reasons for oral biofilm resistance to PDT is the reduced may be to the level of photosensitizer penetration.33 This may indicate that when MB penetrates deeper, its biological and biomolecular effects become stronger, resulting in both more substantial destruction in the deeper layers of a biofilm and more killing of bacteria overall.The variable bactericidal effects of PDT on biofilm of different ages could be due to bacterial concentration differences in younger and older biofilms when compared with biofilm at the stationary peak phase. The bacterial density in each biofilm would be different between the different phases. Given a greater amount of EPS/bacteria ratio, using the same given PDT dose will produce higher killing in the biofilms with lower bacterial counts.Although the total bacterial concentration to start biofilms with was equal in all experiments, when 2 different phases were mixed, probably only the bacteria of the stationary (48 hours) phase were attached and spread to a considerable extent leaving no space for the bacteria in an exponential phase that was probably busy dividing and competing for the available nutrients. This makes only half of the total S mutans in the bacterial suspension available to initiate the adhesion process and leading to a very weak signal of AB assay.The inability of water jets to altogether remove the biofilms from the germanium substrate points out the difficulties of "complete" removal of a biofilm from a substratum with relatively high critical surface tension such as implant surface.Therefore, future research focusing on enhancing mechanisms to affect the adhesion of biofilms to implant surface rather than the cohesion within bacteria is highly recommended. It is unlikely that chemical agents such as photosensitizer would affect the primary adhesion, which takes place between the surface and the bacterial cells that are influenced by physical interactions (hydrophobic, electrostatic).The results of this work are consistent with proposals that PDT induces oxidative embrittlement and fragmentation of plaque/biofilm matrix biopolymers, allowing more effective removal by hydrodynamic (rinsing) forces. The results of this study may direct future clinical investigations for treating peri-implantitis using laser therapy combined with irrigations.Oral biofilm is unique as the mouth is an open cavity where rinsing can detach the biofilm. Unlike the health concerns of loose biofilm within a closed human cavity, detaching the strongly adhered oral biofilms is as important if not more important than killing the bacteria within the biofilm. This project involved laboratory experiments conducted by a team of a clinician, scientists, and photophysics experts as an essential collaboration to resolve a complex clinical problem that cannot be answered by looking for a simple answer from 1 discipline. It is essential to bridge the in-vitro studies with potential clinical research possibilities to translate necessary knowledge to clinicians who deliver health care. Photodynamic therapy is not only able to kill oral flora, but it has the potential to weaken the biofilm around peri-implantitis for more accessible biofilm release from a delicate biomaterial surface.The authors would like to acknowledge Dr Robert Baier for his help in statistical analysis. This work was done as a requirement for the Master's degree.No authors report any conflicts of interest.

Multiple years of international trials in both oceanic and freshwater sites have led to successful easy-release coatings based on the methyl-silicone polymers now widely employed as substitutes for tributyltin- and copper-based ship bottom paints. These have been found to be too soft for harsh conditions, especially during abrasion, but do serve for useful periods in commercial and military circumstances where abrasion is not frequent. This chapter reviews abrasion-related research of the past 20 years that identifies a novel version of silicone-based coatings with a retained easy-release value of Critical Surface Tension (CST) of about 26 mN/m, compounded with a tough epoxy component that allows the two-component coating to survive and function well in extremely abrasive circumstances. This coating has been applied to a power plant’s large intake grate (“rack”) subject to debris impact and intense zebra mussel fouling, an airfoil blade coating showing significantly lower drag than competitive paints, a turbine encasement seal layer remaining functional in zebra mussel-infested waters, and an easy-release surface for flash-frozen ice, simultaneously also resisting damage by transit through ice floes. The coating is formulated using polymeric methyl-silicone granules that are dispersed within an oil-in-water multiple emulsion in an epoxy base that maintains excellent substratum adhesion while allowing the methyl-silicone-based matter to dominate and be continuously refreshed via minimum wear at the environmental interface.

The currently reported study employed the curiously named (but simple) quantitative, nondestructive technique of Multiple Attenuated Internal Reflection InfraRed (MAIR-IR) spectroscopy to assess daily variations of both saliva and vaginal secretions from a panel of consenting volunteers. The project goal was to determine whether the protein-to-carbohydrate (starch) ratio, determined by MAIR-IR analysis of salivary and vaginal secretions is an objective measure of the co-variation of mucinous secretions with daily menstrual cycle. Overall, the spectral data were found to provide valid signatures of vaginal mucus chemical changes that also correlated with cyclic periods of presumed fertility, such periods exhibiting repeat times of 14-16 days and 27-29 days in the thoroughly analyzed records. At mid-cycle, associated with ovulatory events, the protein-to-carbohydrate ratio of vaginal mucin maximizes. Higher carbohydrate ratios are associated with stiffer cervical mucus plug formation, which usually prevents infection, spontaneous abortion, and pre-term birth, but may also be responsible for infertility. Mucin relaxation compounds, such as the FDA-approved oral rinse, delmopinol, may induce fertility in such cases.

Retinal detachments create two pathological surfaces, the surface of the outer neural retinal, and an apical retinal-pigmented epithelium (RPE) surface. The physicochemical properties of these two new surfaces are poorly understood. At a molecular level little is known how detachments form, how to optimize reattachment, or prevent extension of the detachment. A major limitation is lack of information about the biophysical consequences of the retina-RPE separation. The primary challenge is determining the molecular properties of the pathological interface surfaces. Here, using detached bovine retina, we show that this hurdle can be overcome through a combination of biophysical and ultrastructural approaches. The outer surface of freshly detached bovine neural retina, and isolated molecular components of the outer retina were subjected to: 1) Contact angle goniometry to determine the critical surface tension of the outer retinal surface, isolated insoluble interphotoreceptor matrix (IPM) and purified interphotoreceptor retinoid binding protein (IRBP); 2) Multiple attenuated internal reflectance infrared (MAIR-IR) spectroscopy was used to characterize the molecular composition of the retinal surface. MAIR-IR depth penetration was established through ellipsometric measurement of barium-stearate films. Light microscopy, immunohistochemistry and electron microscopy defined the structures probed spectroscopically. Furthermore, the data were correlated to IR spectra of docosahexaenoic acid, hyaluronan, chondroitin-6-sulfate and IRBP, and imaging by IR-microscopy. We found that the retinal critical surface tension is 24 mN/m, similar to isolated insoluble IPM and lower than IRBP. Barium-stearate calibration studies established that the MAIR-IR spectroscopy penetration depth was 0.2 μm. Ultrastructural observations and MAIR-IR studies of isolated outer retina components determined that the pericellular IPM coating the outer retinal surface is primarily responsible for these surface properties. The critical surface tension of detached bovine retina is dictated not by the outer segments, but by a pericellular IPM covering the outer segment tips.

Extremophilic microbes, Pseudomonas syzgii, from the ultrapure water of computer circuit fabrication facilities, crystallize semiconductor matter around themselves while remaining biologically active in a novel form of biochips. The search for extremophilic organisms with similar abilities was extended to volcanic rock from “wellness” water filters. A volcanic rock material called Taicho stone was identified as harboring subterranean Sphingomonas species known to selectively destroy monoaromatic pollutants. They are also water-flow re-activated and productive of substantial exopolymeric substances related to the claimed multiple health-related benefits of its filtered water. Attempts to convert these Sphingomonas sp. from the stone host to germanium oxide crystalline host began with the filtered water aggressively corroding germanium substrata, as with Pseudomonas syzgii. Although semiconductors have not yet stably incorporated these biota, their roles in accelerating superficial biocorrosion suggests their additional utility as non-abrasive biochemical/ mechanical polishing aids. Recognizing that extraterrestrial exobiology has posited numerous similar microbes occluded in minerals, the possibilities for functional organism-based biochip fabrication are diverse when successful semiconductor incorporation and communication are achieved. The results suggest that the best sources for organism-based biochip production will be from endolithic media.

Event Abstract Back to Event Suppressing cavitation-induced noise from articulating ceramic implants Canaan Tyner1, Anne Meyer1 and Robert Baier1 1 University at Buffalo, School of Dental Medicine, United States Introduction: In the process of testing new CAD/CAM-milled, patient-specific ceramic-on-ceramic (Lithium Disilicate, LS2) Temporomandibular Joint (TMJ) implants, stick-slip frictional noises similar to those found by others with all-ceramic artificial hip articulations[1] were noted. Surprisingly, when the plates or simulated joints were lubricated by water or saline to mimic the in vivo environment, the noise intensity INCREASED and shifted to higher-frequency components. This counter-intuitive finding was explainable as cavitation-induced vapor pocket implosion sounds from the shearing under pressure of effectively water-wetted ceramic over ceramic, as had earlier been noted with opening-closing motions of pyrolytic carbon heart valves[2]. This investigation sought to suppress such noises with a covalently bound monolayer coating of low-surface-energy, hydrophobic octadecylsilane (ODS). Methods and Materials: Polished slices of heat-cured LS2 were provided by dental manufacturer IvoclarVivadent from ingots prepared for milling of aesthetic crowns of restored teeth. As supplied, they were water-wettable and further cleaned by Radio Frequency Glow Discharge Treatment (RFGDT) before friction measurement in ceramic-on ceramic couples in custom-constructed apparatus[3], dry and then water-wetted. The flat ceramic samples were then dried and again RFGDT before soaking in an ODS-benzene solution for conversion to hydrophobic surfaces by this C18, methyl-terminated hydrocarbon. Dry and water-wet friction measurements were repeated with the ODS-coated samples (3 cycles over a total elapsed time of 50 minutes). In both experiments, audible sound (squeaking) was monitored by ear. Alternatively, in an implant application, 2 pairs of patient-specific curvilinear LS2 condylar surfaces and fossa segments were prepared by CAD/CAM-directed CEREC machining and articulated in a Proto-tech Oral Wear Simulator (impact-and-sliding) to simulate 6 months of wear. One pair was ODS-coated; the other was used as prepared. Open-source Audacity software was used to acquire noise signatures of sound intensity vs frequency for dry or wet, clean or ODS-coated condyle/fossa articulating couples. Results and Discussion: The dry-on-dry coefficient of friction (CoF) for the flat RFGDT ceramic-on-ceramic slices was reduced from 0.50 to 0.25 after coating the ceramic surfaces with covalently bound ODS. In both cases (RFGDT, ODS), the dry-on-dry conditions produced no squeaking sounds. When wet with distilled water, however, the flat RFGDT samples began to squeak immediately; the ODS-coated samples did not. After drying, both conditions returned to quiet operation. It was interesting to note that the apparent CoF of the flat ODS-coated samples increased when wet and, after 20 total minutes of wet and dry operation, began to squeak slightly (but only when wet). The dry-on-dry CoF of the ODS-coated samples gradually increased during the 50-minute experiment, which included 3 cycles of dry and wet conditions (Figure 1). In preliminary simulated wear experiments with condyle/fossa pairs, there was little difference in sound between the ODS-coated v. clean conditions. Both produced high-frequency squeaking after an initial period of relative silence. Surface analyses indicated that the ODS coating was removed during the 6-month simulation. Replicate experiments and analyses are in progress. Conclusions: Prior literature for pyrolytic carbon heart valves demonstrated that collapse of separation-induced liquid cavitation bubbles was responsible for high-frequency sound accompanying jet impingement (cavitation) damage. Undesirable noise produced by wet ceramic-on-ceramic friction couples may also emanate from cavitation. A significant portion of this sound can be reduced by hydrophobic low-surface-energy coating of the ceramics, while also reducing CoF. Significantly improved longevity of the coating will be required to consider its application for clinical devices. UB School of Dental Medicine - Dean's Vision Fund (CT)References:[1] Ki S-C, Kim B-H, Ryu J-H, Yoon D-H, Chung Y-Y (2011) Squeaking sound in total hip arthroplasty using ceramic-on-ceramic bearing surfaces. J Orthopaed Sci 16(1):21-25.[2] Guo GX, Xu CC, Hwang NHC (1990) Laser assessment of leaflet closing motion in prosthetic heart valves. J Biomed Eng 12(6):477-481.[3] Meyer AE, Baier RE, Chen H, Chowhan M (2006) Tissue-on-tissue testing of dry eye formulations for reduction of bioadhesion. J Adhesion 82(6):607-627. Keywords: Mechanism, joint replacement, Microfriction, Implant wear Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Environmentally sensitive biomaterials Citation: Tyner C, Meyer A and Baier R (2016). Suppressing cavitation-induced noise from articulating ceramic implants. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01424 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Canaan Tyner Anne Meyer Robert Baier Google Canaan Tyner Anne Meyer Robert Baier Google Scholar Canaan Tyner Anne Meyer Robert Baier PubMed Canaan Tyner Anne Meyer Robert Baier Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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Exposure of dental abutments to cleaning and sterilizing Radio Frequency Glow Discharge Treatment (RFGDT) triggered greater degrees of human gingival fibroblast (HGF) attachment and spreading over their surfaces. Enhanced cell growth and metabolic activity of such HGFs were found which might lead to improved cellular margins in the smile-revealing "esthetic zone". This investigation, approved by the Institutional Review Board, employed in vitro studies of HGFs to support in vivo clinical applications of differentially treated titanium healing abutments to demonstrate the possible improvements for tissue growth around dental implants. Harvested commercially pure titanium (cpTi) abutments from three clinical cases per group revealed that separation of the abutments from the human gingival tissues occurred mainly intercellularly rather than directly from the tissue, suggesting that placement of an RFGDT permanent abutment would trigger tissue-integration more completely than noted with usual alcohol-cleaned abutments. This work confirmed and extended observations of prior studies that RFGDT materials have mitogenic effects that might be captured for stimulating desired tissue growth around implanted biomaterial appliances. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 169–177, 2017.

Cite this article: Baier RE, Meyer AE, Aronica MJ, Merrick JM, Murphy TF, et al. (2016) Induced Pseudomonas Aeruginosa Biofilm-Matrix Collapse Fluidizes Cystic Fibrosis Sputum. JSM Biotechnol Bioeng 3(5): 1066. *Corresponding author Robert E. Baier, Department of Oral Diagnostic Sciences, 3435 Main St. Buffalo, NY 14215 State University of New York at Buffalo, School of Dental Medicine, USA, Tel: 716-829-3560; Email:

Background: Dental implants are commonly used today for the treatment of partially and fully edentulous patients. Despite the high success rate they are not resistant to complications and failure due to a variety of problems including peri-implantitis or peri-mucositis due to bacterial biofilm formation on the implant surface. The use of non-surgical and surgical treatment procedure to promote healing in cases with peri-implantitis have limited efficacy. Here we studied the ability of photodynamic therapy to destroy a known bacterial pathogen and the extracellular matrix architecture of biofilm attached to titanium plates and germanium prisms.Methods: Titanium plates or germanium prisms were incubated for 24 h with Fusobacterium nucleatum a fusiform, gram-negative bacterium was used to enable biofilm formation. Photodynamic therapy was carried out by incubating the biofilm samples on each substrata with porfimer sodium. Treatment was carried out using a diode laser at 630 nm, 150 mW/cm(2) for light doses ranging from 25-100 J/cm(2). Evaluation of killing efficacy was done by counting colony forming units compared to controls. Multiple attenuated internal reflection-infrared spectroscopy (MAIR-IR) and SEM were used to analyze the samples pre and post PDT for validation.Results: F. nucleatum was significantly reduced in a dose dependent manner by treatment with PDT. Changes in biofilm components and strength of bioadhesion were examined with MAIR-IR following jet impingement using calibrated water jets. SEM demonstrates significant morphological alterations in the bacteria, consistent with damage associated with exposure to reactive oxygen species.Conclusion: The results are indicative that aPDT is a method that can be used to eradicate micro-organisms associated with biofilm in peri-implantitis on relevant substrata. Data shows that the slime layer of the biofilm is removed and that further methods need to be employed to completely remove weakened or destroyed biofilm matrix components. Reactive oxygen species (ROS) mediated oxidative damage results in morphologic changes as a consequence of changes in cell membrane integrity. (C) 2015 Elsevier B.V. All rights reserved.

More than 50 years have passed since it was first recognized that the surface properties, and predominantly the surface energies of materials controlled their interactions with all biological phases via their spontaneous acquisition of proteinaceous "conditioning films" of differing degrees of denaturation but usually of the same substances within any given system. This led to the understanding that useful engineering control of such interactions could thus be manifested through adjustments to those surface properties, giving significant control and utility to the biomaterials developer without requiring detailed discovery of the biological specifications of the components involved. Thus, effective selection of adhesive versus abhesive (non-stick, non-retention) outcomes for such useful appliances as dental implants versus substitute blood vessels, or water-resistant bonded structures versus clean, nontoxic ship bottoms is now facilitated with little biological background required. A historical overview is presented, followed by a brief survey of the forces involved and most useful analyses applied. Utility for blood-contacting materials is described in contrast to utility for bone- and tissue-contacting materials, demonstrating practical uses in controlling cell-surface interactions and preventing biofouling. New research directions being explored are noted, urging applications of this prior knowledge to replace the use of toxicants.