Comparative Efficacy in Preventing Plaque Formation around Pit and Fissure Sealants: A Clinical Trial.

AIM: The purpose of this study is to compare the clinical performance of an organo-selenium-containing pit and fissure sealant with that of a selenium-free sealant for clinical retention and prevention of plaque and caries development around the sealants. MATERIALS AND METHODS: Following an in vitro study confirming the antimicrobial effect of an organo-selenium-containing pit/fissure sealant [DenteShield™ (DS)], 120 adolescents (7-20 years old) at varying caries risk status had DS sealant applied to a single tooth on the left or the right side of the dentition and UltraSeal™ XT Plus (UXT) on a corresponding tooth on the opposite side. Sealants' assessment was performed quarterly for 1 year for clinical retention, plaque, and caries formation around the sealant. Each sealant lost was replaced but considered as a failure in further analysis. McNemar's test was used to statistically analyze the outcome variables at each assessment time point. RESULTS: While 7% and 12% plaque growth was observed around the UXT sealant at 9th and 12th months, respectively, DS exhibited 100% prevention of plaque growth. Both sealants exhibited 100% caries prevention. Clinical retention did not significantly differ between DS and UXT at all assessment time points except at 12 months when DS showed statistically significantly (p < 0.001) better retention (96%) than UXT (81%). CONCLUSION: In this study, while both sealants are equally effective in caries prevention, DS completely prevented plaque growth around it with better clinical retention than UXT that offered only limited protection against plaque growth. CLINICAL SIGNIFICANCE: Being antimicrobial, DS pit and fissure sealant may be the best sealant option for patients whose caries risk status is due to poor oral hygiene.

Organoselenium Polymer Inhibits Biofilm Formation in Polypropylene Contact Lens Case Material.

OBJECTIVES: Contact lens-acquired bacterial infections are a serious problem. Of the reported cases, inadequate cleaning of the lens case was the most common cause of lens contamination. Organoselenium has been shown to inhibit bacterial attachment to different polymer materials. This study evaluates the ability of an organoselenium monomer, incorporated into the polymer of a polypropylene contact lens case coupon, to block the formation of biofilms in a lens case. METHODS: The bacteria tested were Pseudomonas aeruginosa, Staphylococcus aureus, Stenotrophomonas maltophilia, and Serratia marcescens. For this study, the bacteria were allowed to grow overnight, in trypticase soy broth media, in the presence of the selenium-containing polymer or the same polymer without organoselenium. The material was studied by both colony-forming unit determination and by confocal laser scanning microscopy. RESULTS: The results showed that the organoselenium polymer versus the control polymer resulted in the following effect on biofilm formation: (1) a reduction in P. aeruginosa of 7.3 logs (100%); (2) a reduction in S. aureus of 7.3 logs (100%); (3) a reduction in S. maltophilia of 7.5 logs (100%); and (4) a reduction in S. marcescens reduction of 3.3 logs (99.9%). To test the stability of the organoselenium polypropylene contact lens coupon, the coupon was soaked in PBS for eight weeks at room temperature. It was found that when these soaked coupons were tested against S. aureus, complete inhibition (8.1 logs) was obtained. Because organoselenium cannot leach from the polymer, this would imply that the organoselenium polypropylene contact lens case coupon would be inhibitory toward bacterial biofilm for the life of the case. CONCLUSION: The organoselenium polypropylene contact lens case coupon shows the ability to inhibit biofilm formation. The use of organoselenium copolymer should play an important role in protecting against contact lens case-acquired infection.

A study on the ability of quaternary ammonium groups attached to a polyurethane foam wound dressing to inhibit bacterial attachment and biofilm formation.

Bacterial infection of acute and chronic wounds impedes wound healing significantly. Part of this impediment is the ability of bacterial pathogens to grow in wound dressings. In this study, we examined the effectiveness of a polyurethane (PU) foam wound dressings coated with poly diallyl-dimethylammonium chloride (pDADMAC-PU) to inhibit the growth and biofilm development by three main wound pathogens, Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii, within the wound dressing. pDADMAC-PU inhibited the growth of all three pathogens. Time-kill curves were conducted both with and without serum to determine the killing kinetic of pDADMAC-PU. pDADMAC-PU killed S. aureus, A. baumannii, and P. aeruginosa. The effect of pDADMAC-PU on biofilm development was analyzed quantitatively and qualitatively. Quantitative analysis, colony-forming unit assay, revealed that pDADMAC-PU dressing produced more than eight log reduction in biofilm formation by each pathogen. Visualization of the biofilms by either confocal laser scanning microscopy or scanning electron microscopy confirmed these findings. In addition, it was found that the pDADMAC-PU-treated foam totally inhibited migration of bacteria through the foam for all three bacterial strains. These results suggest that pDADMAC-PU is an effective wound dressing that inhibits the growth of wound pathogens both within the wound and in the wound dressing.

The in vitro efficacy of betadine antiseptic solution and colloidal silver gel combination in inhibiting the growth of bacterial biofilms.

INTRODUCTION: Betadine (Povidone-Iodine) solution is a topically applied antiseptic, which has been used routinely used in wound care and general surgery to prevent skin and wound infections. However, several studies have documented the ineffectiveness of betadine. Other topical antimicrobial dressings, including those that contain silver, have been used in the management of infected wounds. The present study was undertaken to determine if the combination of 5% betadine solution and silver colloidal gel (Ag-gel) is more effective than either substance alone in inhibiting the growth gram-negative and gram-positive bacteria. METHODS: The effectiveness of 5% betadine solution and Ag-gel as anti-microbial agents were assessed using both colony forming unit (CFU) assay and confocal laser scanning microscopy (CLSM). RESULTS: Ag-gel showed complete inhibition on all the bacteria species examined except the Klebsiella pneumoniae clinical isolate (CL) strain while 5% betadine concentrations did not completely kill any of the tested bacteria. In contrast, K. pneumoniae was completely eliminated in the presence of both 5% betadine solution and Ag-gel together. The CLSM showed similar findings to the CFU results examining the 5% betadine solution and Ag-gel combination. CONCLUSIONS: This study demonstrated that while the individual treatments using either 5% betadine solution and Ag-gel alone were infective antimicrobial agents, the combination of 5% betadine solution and Ag-gel was superior at eliminating all tested bacteria, including K. pneumoniae CL.

Organo-selenium containing dental sealant inhibits biofilm formation by oral bacteria.

OBJECTIVE: Dental plaque is a complex structure (called a biofilm) that is produced by a community of oral bacteria. As microorganisms accumulate in the oral cavity, bacteria can assemble into biofilms that protect them from antibiotics and disinfectants, which contribute to dental cavities and oral infections that acts as the seed for further infections throughout the body. Therefore, there is great interest in developing dental sealants that can effectively eliminate biofilms formed from an assortment of oral bacteria species. METHODS: In previous papers, it was shown that both in vivo and in vitro use of organo-selenium dental sealants have the potential to be an effective method for preventing dental caries and plaque formation. However, our previous in vitro study only examined the effect of the organo-selenium sealants on Streptococcus mutans and salivarius. Since that time, this organo-selenium sealant has been changed to improve its curing time. RESULTS: We showed a selenium containing sealant (SeLECT-DefenseTM) can completely eliminate biofilm formation on the sealant at selenium concentrations of 0.25% and higher, by S. salivarius, S. sanguinis, or S. mutans, individually or in combination. This selenium containing sealant can also completely inhibit the same bacteria from growing under the sealant, while control sealant cannot. The selenium containing sealant was tested for stability and it was found to still kill these same bacteria after soaking for the equivalent of one year in PBS (pH 7.4). It was also found that the combination of the three bacteria were also killed by the selenium sealant, thus ruling out potential synergism of the bacteria in forming resistance. SIGNIFICANCE: The following study showed that this modified selenium dental sealant effectively eliminates species of bacteria both on and under the dental sealant.

The efficacy of organo-selenium conjugated cellulose polymer dressing to inhibit Candida albicans biofilm formation.

Selenium covalently bonded to cellulose can catalyze the formation of superoxide radicals. Candida albicans, colonizes epithelial surfaces and can be a fatal infection in immunocompromised people. In this study, we demonstrated the ability of organo-selenium, covalently attached to cotton textile dressings to kill C. albicans biofilms.

Patterned Electrospinning: A Method of Generating Defined Fibrous Constructs Influencing Cell Adhesion and Retention.

A critical component of tissue engineering is the ability to functionally replace native tissue stroma. Electrospinning is a technique capable of forming fibrous constructs with a high surface area for increased cell-material interaction and enhanced biocompatibility. However, physical and biological properties of electrospun scaffolds are limited by design controllability on a macroscale. We developed a methodology for generating electrospun scaffolds with defined patterns and topographic features to influence physical properties and biological interactions. Five unique design electrospinning target collectors were fabricated to allow for generation of defined polymeric scaffold patterns including lines, sinusoids, squares, zigzags, and solid. Poly(lactic-co-glycolic) acid was electrospun under identical conditions utilizing these varied targets, and constructs generated were examined as to their physical configuration, mechanical and chemical properties, and their ability to foster vascular smooth muscle cell adhesion and retention at 24 h. Modifying collector designs led to significant differences in fiber target coverage ranging from 300 mm2 for solid (100% of the target area) to 217.8 mm2 for lines (72.6% of the target area). Measured fiber excess, residual open area, and contact angle (hydrophobicity) followed the same trend as fiber target coverage with respect to the collector pattern: lines > sinusoids > squares > zigzags > solid. Similarly, the line design allowed for the greatest cell adhesion and retention (258 ± 31 cells), whereas solid exhibited the lowest (150 ± 15 cells); p < 0.05. There was a strong direct correlation of cell adhesion to construct residual open area (R2 = 0.94), normalized fiber excess (R2 = 0.99), and fiber grammage (R2 = 0.72), with an inverse relationship to fiber target coverage (R2 = 0.94). Our results demonstrate the ability to utilize patterned collectors for modifying macroscopic and microscopic electrospun scaffold features, which directly impact cell adhesion and retention, offering translational utility for designing specific tissue constructs.

Organoselenium coating on cellulose inhibits the formation of biofilms by Pseudomonas aeruginosa and Staphylococcus aureus.

Among the most difficult bacterial infections encountered in treating patients are wound infections, which may occur in burn victims, patients with traumatic wounds, necrotic lesions in people with diabetes, and patients with surgical wounds. Within a wound, infecting bacteria frequently develop biofilms. Many current wound dressings are impregnated with antimicrobial agents, such as silver or antibiotics. Diffusion of the agent(s) from the dressing may damage or destroy nearby healthy tissue as well as compromise the effectiveness of the dressing. In contrast, the antimicrobial agent selenium can be covalently attached to the surfaces of a dressing, prolonging its effectiveness. We examined the effectiveness of an organoselenium coating on cellulose discs in inhibiting Pseudomonas aeruginosa and Staphylococcus aureus biofilm formation. Colony biofilm assays revealed that cellulose discs coated with organoselenium completely inhibited P. aeruginosa and S. aureus biofilm formation. Scanning electron microscopy of the cellulose discs confirmed these results. Additionally, the coating on the cellulose discs was stable and effective after a week of incubation in phosphate-buffered saline. These results demonstrate that 0.2% selenium in a coating on cellulose discs effectively inhibits bacterial attachment and biofilm formation and that, unlike other antimicrobial agents, longer periods of exposure to an aqueous environment do not compromise the effectiveness of the coating.

Efficacy of a silver colloidal gel against selected oral bacteria in vitro.

Background: It is necessary to develop new strategies to protect against bacteria such as S treptococcus mutans, S treptococcus sanguis, and Streptococcus salivarius, which contribute to tooth decay and plaque formation. Our current study investigated the efficacy of a colloidal silver gel in inhibiting biofilm formation by these principal oral bacteria , in vitro. The aim of this study was to assess the efficacy of a colloidal silver gel formulation for inhibiting bacterial biofilm formation (Ag-gel) by the principal bacteria that cause plaque formation and tooth decay. Methods: The effect of Ag-gel on viability of S. mutans, S. sanguis, and S. salivarius was assessed by quantifying their colony forming units (CFU) in presence or absence of the test gel. The effect of this formulation on biofilm-forming ability of these bacteria was studied through scanning electron microscopy. Results: Using the CFU assays, over 6 logs of inhibition (100%) were found for S. mutans, S. sanguis, and S. salivarius for the Ag-gel-treated bacteria when compared with the control gel. In addition, the Ag-gel also inhibited biofilm formation by these three bacteria mixed together. These results were confirmed by scanning electron microscopy. Conclusions: The Ag-gel was effective in preventing biofilm formation by S. mutans, S. sanguis, and S. salivarius. This Ag-gel should be tested for the ability to block plaque formation in the mouth, through its use as a tooth paste.

Cryomilled zinc sulfide: A prophylactic for Staphylococcus aureus-infected wounds.

Bacterial pathogens that colonize wounds form biofilms, which protect the bacteria from the effect of host immune response and antibiotics. This study examined the effectiveness of newly synthesized zinc sulfide in inhibiting biofilm development by Staphylococcus aureus ( S. aureus) strains. Zinc sulfide (ZnS) was anaerobically biosynthesized to produce CompA, which was further processed by cryomilling to maximize the antibacterial properties to produce CompB. The effect of the two compounds on the S. aureus strain AH133 was compared using zone of inhibition assay. The compounds were formulated in a polyethylene glycol cream. We compared the effect of the two compounds on biofilm development by AH133 and two methicillin-resistant S. aureus clinical isolates using the in vitro model of wound infection. Zone of inhibition assay revealed that CompB is more effective than CompA. At 15 mg/application, the formulated cream of either compound inhibited biofilm development by AH133, which was confirmed using confocal laser scanning microscopy. At 20 mg/application, CompB inhibited biofilm development by the two methicillin-resistant S. aureus clinical isolates. To further validate the effectiveness of CompB, mice were treated using the murine model of wound infection. Colony forming cell assay and in vivo live imaging results strongly suggested the inhibition of S. aureus growth.

Physical Characterization and Platelet Interactions under Shear Flows of a Novel Thermoset Polyisobutylene-based Co-polymer.

Over the years, several polymers have been developed for use in prosthetic heart valves as alternatives to xenografts. However, most of these materials are beset with a variety of issues, including low material strength, biodegradation, high dynamic creep, calcification, and poor hemocompatibility. We studied the mechanical, surface, and flow-mediated thrombogenic response of poly(styrene-coblock-4-vinylbenzocyclobutene)-polyisobutylene-poly(styrene-coblock-4-vinylbenzocylcobutene) (xSIBS), a thermoset version of the thermoplastic elastomeric polyolefin poly(styrene-block-isobutylene-block-styrene) (SIBS), which has been shown to be resistant to in vivo hydrolysis, oxidation, and enzymolysis. Uniaxial tensile testing yielded an ultimate tensile strength of 35 MPa, 24.5 times greater than that of SIBS. Surface analysis yielded a mean contact angle of 82.05° and surface roughness of 144 nm, which was greater than for poly(ε-caprolactone) (PCL) and poly(methyl methacrylate) (PMMA). However, the change in platelet activation state, a predictor of thrombogenicity, was not significantly different from PCL and PMMA after fluid exposure to 1 dyn/cm(2) and 20 dyn/cm(2). In addition, the number of adherent platelets after 10 dyn/cm(2) flow exposure was on the same order of magnitude as PCL and PMMA. The mechanical strength and low thrombogenicity of xSIBS therefore suggest it as a viable polymeric substrate for fabrication of prosthetic heart valves and other cardiovascular devices.

Core-shell PVA/gelatin electrospun nanofibers promote human umbilical vein endothelial cell and smooth muscle cell proliferation and migration.

Cardiovascular disease is the leading cause of death in the world. In this study, coaxial electrospinning is employed to fabricate fibers in a core-shell structure with polyvinyl alcohol (PVA) in the core and gelatin in the shell for evaluation as a potential vascular tissue engineering construct. PVA, a synthetic polymer, provides mechanical strength to the biocompatible and weak gelatin sheath. The HUVEC (human umbilical vein endothelial cells) and rSMC (rat smooth muscle cells) demonstrated a flattened morphology with multiple attachment sites on the gelatin and coaxial scaffolds, with an increase in cell spreading seen as mechanical stiffness of the scaffold increased. Additionally, HUVEC had an increase in migration on the coaxial scaffolds, which was attributed to the increase in stiffness; however, this increase in migration was not seen with the rSMC, which had the highest outward migration on the flat surfaces (tissue culture polystyrene and gelatin film). Overall, these scaffolds are appealing substrates for vascular tissue engineering applications. STATEMENT OF SIGNIFICANCE: The worldwide burden of cardiovascular disease presents an ongoing need and opportunity for creating a variety of vascular prostheses. Fabrication of novel scaffolds and constructs for these are needed, providing strength and biological properties facilitating endothelial (EC) and smooth muscle (SMC) cell attachment, migration, and integration. Using electrospinning we formed 3D core:shell nanofibers and examined their effectiveness as substrates for EC and SMC attachment and growth, compared to a 2D (flat) substrate. We found that ECs attached and grew best on 3D core:shell fibers, whereas SMCs favored 2D gelatin surfaces. Interestingly, we found that EC attachment, migration and growth correlated and improved with increasing fiber stiffness. These materials and insights may foster novel vascular prostheses development.

Hemocompatibility of Poly(vinyl alcohol)-Gelatin Core-Shell Electrospun Nanofibers: A Scaffold for Modulating Platelet Deposition and Activation.

In this study, we evaluate coaxial electrospun nanofibers with gelatin in the shell and poly(vinyl alcohol) (PVA) in the core as a potential vascular material by determining fiber surface roughness, as well as human platelet deposition and activation under varying conditions. PVA scaffolds had the highest surface roughness (Ra=65.5±6.8 nm) but the lowest platelet deposition (34.2±5.8 platelets) in comparison to gelatin nanofibers (Ra=36.8±3.0 nm and 168.9±29.8 platelets) and coaxial nanofibers (1 Gel:1 PVA coaxial, Ra=24.0±1.5 nm and 150.2±17.4 platelets. 3 Gel:1 PVA coaxial, Ra=37.1±2.8 nm and 167.8±15.4 platelets). Therefore, the chemical structure of the gelatin nanofibers dominated surface roughness in platelet deposition. Due to their increased stiffness, the coaxial nanofibers had the highest platelet activation rate, rate of thrombin formation, in comparison to gelatin and PVA fibers. Our studies indicate that mechanical stiffness is a dominating factor for platelet deposition and activation, followed by biochemical signals, and lastly surface roughness. Overall, these coaxial nanofibers are an appealing material for vascular applications by supporting cellular growth while minimizing platelet deposition and activation.

Linear fibroblast alignment on sinusoidal wave micropatterns.

Micrometer and nanometer grooved surfaces have been determined to influence cellular orientation, morphology, and migration through contact guidance. Cells typically elongate along the direction of an underlying groove and often migrate with guidance provided by constraints of the pattern. This phenomenon has been studied primarily using linear grooves, post, or well patterns. We investigated the behavior of mouse embryonic fibroblasts on non-linear, sinusoidal wave grooves created via electron beam lithography on a polymethyl methacrylate (PMMA) substrate that was spin-coated onto a positively charged glass surface. Three different wave patterns, with varying wavelengths and amplitudes, and two different line patterns were created. Cell orientation and adhesion was examined after 4, 24, and 48 h after cell seeding. Attachment strength was studied via subjecting cells on substrates to centrifugal force following a 24-h incubation period. For all wave patterns studied, it was noted that cells did not reside within the groove, rather they were observed to cross over each groove, residing both inside and outside of each wave pattern, aligning linearly along the long axis of the pattern. For the linear patterns, we observed that cells tended to reside within the grooves, consistent with previous observations. The ability to add texture to a surface to manipulate cell adhesion strength and growth with only localized attachment, maintaining free space in curvilinear microtopography underlying the cell, may be a useful addition for tissue engineering and the fabrication of novel biomedical devices.

Inhibition of otopathogenic biofilms by organoselenium-coated tympanostomy tubes.

IMPORTANCE: Tube occlusion and post-tympanostomy tube otorrhea (PTTO) are 2 major sequelae of tympanostomy tube placement. Plugging negates the function of the tympanostomy tubes and, along with chronic PTTO, can be financially burdensome owing to repeated surgical procedures and additional treatments. OBJECTIVE: To investigate the effectiveness of an organoselenium (OSe) coating on Donaldson tympanostomy tubes in inhibiting biofilm formation on the tympanostomy tubes. DESIGN: In vitro microbiologic study; all experiments were performed in a Texas Tech University Health Sciences Center basic sciences laboratory. INTERVENTIONS: Inhibition of biofilm formation was investigated by incubating OSe-coated vs uncoated (control) tympanostomy tubes in a nutrient broth containing either Staphylococcus aureus (Sa) expressing green fluorescent protein (GFP), nontypeable Haemophilus influenzae (NTHi) expressing GFP, or Moraxella catarrhalis (Mc) for 48 hours at 37 °C. All biofilms were quantified via colony-forming unit (CFU) assays. The Sa and NTHi biofilms were visualized using confocal laser-scanning microscopy (CLSM) and analyzed using the COMSTAT program. MAIN OUTCOMES AND MEASURES: The CFU assays, CLSM, and COMSTAT analysis revealed that compared with uncoated control tympanostomy tubes, OSe-coated tympanostomy tubes are able to inhibit Sa, NTHi, and Mc biofilm formation. RESULTS: The Sa and NTHi developed thick mature biofilms containing considerable biomass on uncoated tympanostomy tubes as determined by CLSM and COMSTAT analysis, while the OSe coating on the tympanostomy tubes drastically inhibited biofilm formation by Sa and NTHi. Quantitative CFU analysis revealed that this reduction in biofilm formation was significant, 6 logs for Sa (P < .001) and 4 logs for NTHi (P = .02). OSe coating also inhibited biofilm formation by Mc with a 4.5-log reduction (P < .001). CONCLUSIONS AND RELEVANCE: The OSe coating is a potential long-lasting agent to prevent biofilm development on tympanostomy tubes by otopathogens.