AIE-active polysiloxane-based fluorescent probe for identifying cancer cells by locating lipid drops.

Comparing with normal cells, Lipid droplets (LDs) of cancer cells show lower polarity and less quantity, which can be utilized as a marker for cancer diagnosis. However, the investigation of LDs in living cancer cells is restricted by the lack of effective molecular tools. Herein, we first reported a novel polysiloxane-based polymer fluorescent polar probe TR-1 with AIE properties, which realized the possibilities for locating LDs. It can aggregate in the LDs of cancer cells and show a stronger fluorescent signal to conduct cancer diagnosis. Moreover, the excellent photostability of TR-1 enable stable fluorescence to exhibit in cancer cells during effective time.

In-situ mineralized robust polysiloxane-Ag@ZnO on cotton for enhanced photocatalytic and antibacterial activities.

A bifunctional interfacial layer was introduced onto the surface of cotton fabric which not only enhanced the interfacial bonding between Ag@ZnO and organic substrates but also improved the photocatalytic performance simultaneously. In detail, a modified cotton fabric (denoted as Cot-g-Si/Ag@ZnO) was fabricated through radiation-induced graft polymerization of γ-methacryloxypropyl trimethoxysilane and followed the in-situ formation of ZnO and loading of Ag nanoparticles simultaneously. Owing to ZnOSi between the graft chains and Ag@ZnO photocatalyst, the charge carrier concentration increased and Ag was prevented from oxidizing through the partial separation from ZnO, leading to enhanced near-field amplitudes of the localized surface plasmon resonance. Cot-g-Si/Ag@ZnO also exhibited excellent photocorrosion resistance, photostability and laundering durability. Its photocatalytic activity was fully maintained after several photodegradation cycles; moreover, after laundering durability test, the photocatalytic activity was improved compared with the newly prepared one. Credible mechanism for the photocatalytic activity of Cot-g-Si/Ag@ZnO under sunlight irradiation is proposed.

Potassium hydroxide treatment of UV-curable polysiloxane-type polymer for reproducible enhancement of cell adhesion and survival.

Polysiloxanes have shown exquisite properties for fabrication of microstructures for various biomedical and biotechnological applications. Nevertheless, their biocompatibility in terms of cell adhesion and survival ability is controversial. A simple polysiloxane modifying procedure that reproducibly enhances cell adhesion was proposed. Sonication of the hybrid organic-inorganic polymer of polysiloxane type, Ormocomp, in potassium hydroxide (KOH)/ethanol solution enhanced adhesion and subsequent survival of a panel of four cell lines. Characterization of surface properties of untreated and KOH-treated Ormocomp coatings has revealed considerable negative charge of Ormocomp substrates based on measurements of zeta potentials. KOH treatment did not modify surface morphology as visualized by scanning electron microscopy, but it resulted in alteration in both chemical composition according to SIMS analysis and hydrophilicity evaluated by static water contact angles. The results suggest that the failure of the adherent cells to survive on Ormocomp coatings is related to cell adhesion. The negative surface charge of Ormocomp substrates may be one of the influencing factors; however, the modification of surface chemistry mediated by KOH and the resulting increase in hydrophilicity accompanied by modification of protein adsorption are more likely responsible for enhanced cell adhesion and survival on Ormocomp coatings. KOH treatment thus may serve as a simple, cost-effective procedure modifying polysiloxane-type polymers that leads to reproducible enhancement of cell adhesion.

Application of microwave irradiation for the removal of polychlorinated biphenyls from siloxane transformer and hydrocarbon engine oils.

The removal of polychlorinated biphenyls (PCBs) both from siloxane transformer oil and hydrocarbon engine oil was investigated through the application of microwave (MW) irradiation and a reaction system based on polyethyleneglycol (PEG) and potassium hydroxide. The influence of the main reaction parameters (MW irradiation time, molecular weight of PEG, amount of added reactants and temperature) on the dechlorination behavior was studied. Promising performances were reached, allowing about 50% of dechlorination under the best experimental conditions, together time and energy saving compared to conventional heating systems. Moreover, an interesting dechlorination degree (up to 32%) was achieved for siloxane transformer oil when MW irradiation was employed as the unique driving force. To the best of our knowledge, this is the first time in which MW irradiation is tested as the single driving force for the dechlorination of these two types of PCB-contaminated oils.

Photopolymerized Network Polysiloxane Films with Dangling Hydrophilic/Hydrophobic Chains for the Biofouling Release of Invasive Marine Serpulid Ficopomatus enigmaticus.

Novel photopolymerized network films based on a polysiloxane matrix containing varied amounts of polyoxyethylene (P3) or perfluorohexylethyl (F) dangling side chains were investigated. For films containing less than 10 wt % P3 and F, the wettability and elastic modulus were similar to those of the photopolymerized network matrix. However, angle-resolved X-ray photoelectron spectroscopy measurements proved that the surface of films with F dangling chains was highly enriched in fluorine depending on both the amount of P3 and F and their relative ratio in the films. The biological performance of the films was evaluated against a new widespread and invasive marine biofoulant, the serpulid Ficopomatus enigmaticus. The diatom Navicula salinicola was also assayed as a conventional model organism for comparison. Films richer in P3 better resisted the settlement and promoted the release of calcified tubeworms of F. enigmaticus.

The disinfection of impression materials by using microwave irradiation and hydrogen peroxide.

STATEMENT OF PROBLEM: Microwave irradiation and immersion in solutions have been recommended for denture disinfection. However, the effect of dry conditions and impression materials has not been completely evaluated. PURPOSE: The purpose of this study was to evaluate the effectiveness of microwave irradiation and hydrogen peroxide for the disinfection of dental impression materials. MATERIAL AND METHODS: Specimens (diameter 10 mm, thickness 2 mm) were made with polyvinyl siloxane. Experimental groups were treated with hydrogen peroxide (group H), microwave irradiation (group M), and a combination of both hydrogen peroxide and microwave irradiation (group MH) for 1 minute, 2 minutes, and 3 minutes. The control group was untreated. The total sample size was 120. The specimens were divided into 2 groups, those exposed to Streptococcus mutans and those exposed to Escherichia coli. The disinfection effect and physical properties (contact angle, compatibility with gypsum, strain in compression, tear strength) were evaluated. RESULTS: All 3 groups (H, M, MH) were effective in reducing the number of colony forming units (CFU) per unit volume (mL) for both S mutans and E coli compared with the control. The most significant reduction in the CFU/mL of both bacteria was noted in the MH group and was used to compare either treatment alone (P<.05). No statistically significant difference was noted between the control and treatment groups in terms of all of the physical properties tested (P>.05). CONCLUSIONS: Microwave irradiation was identified as a useful disinfection method against S mutans and E coli, especially when combined with H2O2, without adversely affecting the physical properties of dental impression materials.

Comparison between a silorane-based composite and methacrylate-based composites: shrinkage characteristics, thermal properties, gel point and vitrification point.

A silorane-based composite was compared against methacrylate-based composites in terms of shrinkage characteristics, thermal properties, gel point, and vitrification point. Shrinkage strain was measured using a laser triangulation method. Shrinkage stress was measured using a stress analyzer. Heat flow during photopolymerization was measured using photo-DSC. Statistical analysis was performed using one-way ANOVA and Tukey's test (p=0.05). Silorane exhibited significantly lower shrinkage strain than the methacrylate-based composites. It also presented the lowest stress values during light exposure, but the highest maximum stress rate after light exposure. It showed the highest heat flow rate, and it took the longest time to reach gel and vitrification points. Silorane demonstrated improved performance over the methacrylate-based composites with delayed gel and vitrification points as well as reduced shrinkage strain and stress. However, a high quantity of heat was liberated during the curing process, causing silorane to show significantly higher stress rate (p<0.05) than the methacrylate-based composites after light exposure.

Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation.

BACKGROUND: This study evaluated the effect of disinfection by immersion and microwave irradiation on the roughness of one denture base resin (Lucitone-L) and five relining materials, three hard (Tokuyama Rebase II-TR, New Truliner-NT, Ufigel Hard-UH) and two resilient (Trusoft-T, Sofreliner-S). METHODS: Fifty specimens were made and divided into groups: CL2 specimens were brushed with 4% chlorhexidine (1 min), immersed in the same solution (10 min) and immersed in water (3 min); MW2 specimens were immersed in water and microwave irradiated (650W; 6 min); CL2 and MW2 specimens were disinfected twice; CL7 and MW7 specimens were submitted to seven cycles using chlorhexidine or microwave irradiation, respectively; W specimens were not disinfected and remained in water (37°C; 7 days). RESULTS: Results were statistically analysed (p = 0.05) and revealed that, at baseline, the highest mean value was observed for T (p < 0.001). Material NT showed increase in roughness after the first (p = 0.003), second (p = 0.001), seventh (p = 0.000) cycles of microwave disinfection and after 7 days of immersion in water (p = 0.033). CONCLUSIONS: Resilient liner S presented significant increase in roughness after the second cycle of disinfection with chlorhexidine (p = 0.003). Material T exhibited significantly decreased roughness in group W (p = 0.010), while microwaving produced severe alterations on its surface.

Silorane-based composite: depth of cure, surface hardness, degree of conversion, and cervical microleakage in Class II cavities.

OBJECTIVE: The purpose of this study was to determine the depth of cure, degree of conversion (DC), hardness, and cervical sealing ability of silorane-based composite (Filtek Silorane [FS; 3M, Seefeld, Germany]) and to compare with methacrylate-based composites (MBCs = Filtek Supreme XT [FSXT] and Filtek P60 [FP60]). MATERIALS AND METHODS: The DC and hardness of every material were evaluated after 1, 7, and 30 days. The depth of cure was determined using the ISO 4049:2000 standard. Microleakage was evaluated by measuring dye penetration across the gingival wall in cross-sectioned specimens. RESULTS: FS showed lower depth of cure than FSXT and FP60. The DC of FS was significantly lower when compared to FP60 and FSXT. FS exhibited lower hardness than both FSXT and FP60 after 1 day of storage. The hardness of FS remained unchanged during the storage period. FS showed reduced microleakage scores compared to FSXT and showed similar microleakage scores compared to FP60. CONCLUSIONS: In conclusion, the DC and cure depth of FS are lower than those of MBCs. However, FS revealed stable hardness in water that is comparable to MBCs. The sealing ability of FS is similar or even better than that of MBCs.

Surface energy and wettability of polymers light-cured by two different systems.

OBJECTIVE: This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. MATERIAL AND METHOD: Filtek Z350 (3M ESPE), Admira (VOCO) and Grandio (VOCO) resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100) using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard) that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. RESULTS AND CONCLUSIONS: No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

Surface energy and wettability of polymers light-cured by two different systems

OBJECTIVE: This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. MATERIAL AND METHOD: Filtek Z350 (3M ESPE), Admira (VOCO) and Grandio (VOCO) resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100) using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard) that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. RESULTS AND CONCLUSIONS: No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

Cellular compatibility of a gamma-irradiated modified siloxane-poly(lactic acid)-calcium carbonate hybrid membrane for guided bone regeneration.

A bi-layered silicon-releasable membrane consisting of a siloxane-poly(lactic acid) (PLA)-vaterite hybrid material (Si-PVH) microfiber mesh and a PLA microfiber mesh has been developed by an electrospinning method for guided bone regeneration (GBR) application. The bi-layered membrane was modified to a three-laminar structure by sandwiching an additional PLA microfiber mesh between the Si-PVH and PLA microfiber meshes (Si-PVH/PLA membrane). In this study, the influence of gamma irradiation, used for sterilization, on biological properties of the Si-PVH/PLA membrane was evaluated with osteoblasts and fibroblasts. After gamma irradiation, while the average molecular weight of the Si-PVH/PLA membrane decreased, the Si-PVH/PLA membrane promoted cell proliferation and differentiation (alkaline phosphatase activity and calcification) of osteoblasts, compared with the poly(lactide-co-glycolide) membrane. These results suggest that the gamma-irradiated Si-PVH/PLA membrane is biocompatible with both fibroblasts and osteoblasts, and may have an application for GBR.

Effect of accelerated aging on permanent deformation and tensile bond strength of autopolymerizing soft denture liners.

PURPOSE: The aim of this study was to evaluate the effect of different accelerated aging times on permanent deformation and tensile bond strength of two soft chairside liners, acrylic resin (T) and silicone (MS) based. MATERIALS AND METHODS: Different specimens were made for each test of each reliner. The specimens (n = 10) were submitted to accelerated aging for 2, 4, 8, 16, 32, and 64 cycles. Tensile bond strength testing was performed at a crosshead speed of 5 mm/min and permanent deformation with a compressive load of 750 gf. Data were submitted to Mann-Whitney test to compare the materials at different times, and Kruskal-Wallis and Dunn tests were used for comparing aging intervals within a given reliner. RESULTS: MS presented a lower percentage of permanent deformation (p < 0.0001) and higher tensile bond strength (p < 0.0001) than T in all time intervals and was not affected by the accelerated aging process, which reduced the permanent deformation and increased tensile bond strength of T (p < 0.05). CONCLUSION: MS presented lower permanent deformation and higher tensile bond strength than T. Although T presented changes in those properties after accelerated aging, both materials might be suited for long-term use.

Surface integrity of solvent-challenged ormocer-matrix composite.

OBJECTIVE: To investigate the surface integrity of solvent-challenged ormocer-matrix composites, photoactivated by different light exposure modes, through surface-hardness measurements at different periods of time; and to compare such behavior with dimethacrylate-based materials. METHODS: One hundred percent ormocer-based matrix (experimental ormocer (ORM)), a commercial mixed dimethacrylate-ormocer-based matrix (Admira (ADR)) and two commercial dimethacrylate-based matrix composites (experimental controls, (Grandio (GRD) and Premise (PRE)) were evaluated. Disk specimens (4 mm × 2 mm) were prepared from each material and light-activated using either a standard (S) or soft-start (SS) light exposure protocol with an LED-curing unit. Top, irradiated surface Knoop hardness (KHN) was measured within the following experimental groups (n=5): Group 1: immediately after exposure; Group 2: after dry and dark storage, Group 3: after storage in distilled water, and Group 4: immersion in absolute ethanol. Hardness of Groups 2-4 were measured after 7 days storage. Immediate hardness values were submitted to Student's t-tests separately for each material. Hardness values after treatments were submitted to two-way ANOVA and Tukey's post hoc test to compare values among different storage media and light exposure mode protocols. Comparisons among materials were described using percentage of hardness change. Statistical testing was performed at a pre-set alpha of 0.05. RESULTS: Immediate hardness values were not affected by the light exposure mode, regardless of the material. In general, exposure mode did not significantly affect hardness after 7 days storage, regardless of storage media or material. After 7 days dry storage, hardness values increased for all materials relative to immediate testing, and decreased after water and ethanol storage, with ethanol showing the greatest effect. The experimental ormocer-based material had the lowest percentage hardness change and thus proved more resistant to solvent degradation than the other materials, regardless of the light exposure method. SIGNIFICANCE: Irradiated surface hardness values and surface integrity were unaffected by light exposure mode, regardless of the material tested. The experimental ormocer-based material presented the least change in hardness as a result of solvent challenge than any of the commercial products: ormocer or conventional resin-based, and thus showed better surface integrity.

Novel polysiloxane-based scintillators for neutron detection.

Polysiloxane-based scintillators are promising for employment in harsh environments, owing to their outstanding radiation resistance and thermal properties over the traditional plastics (polyvinyltoluene and polystyrene). In this work, cross-linked polydimethyl-co-diphenylsiloxane (PMPS) scintillators with 22% molar percentage of diphenylsiloxane units have been synthesised. 2,5-Diphenyloxazole and Lumogen Violet (BASF) were employed as primary and secondary fluor, respectively. Thermal neutrons sensitivity was achieved through the addition of 3% wt of ortho-carborane. Scintillation yield measurements were made by exciting with (241)Am alpha source samples with different concentrations of dye molecules. PMPS-based scintillators with ∼50% light yield as compared with the commercial plastic scintillator EJ212 were produced. The scintillation yield of the B-loaded samples under thermal neutrons was tested with a moderated Am-Be source and compared with the commercially available EJ254 (5% wt B). 2.2 MeV neutrons were produced by irradiating with a 4.0 MeV proton beam an LiF target, thus exploiting the reaction (7)Li(p,n)(7)Be. Time-of-flight measurements were performed to distinguish pulses due to neutrons or gamma. A similar test was performed with an EJ254 commercial scintillator for comparison. Using the same set-up, polyethylene bricks were used as a moderator to produce low-energy neutrons for testing B-loaded samples.

Monomer elution from nanohybrid and ormocer-based composites cured with different light sources.

OBJECTIVES: To study monomer elution from four resin-based composites (RBCs) cured with different light sources. METHODS: Twenty-eight premolars were randomly allocated to four groups. Standardized cavities were prepared and restored with a nanohybrid (Filtek Supreme XT or Tetric EvoCeram), an ormocer (Admira) or a microhybrid RBC (Filtek Z250) which served as control. Buccal restorations were cured with a halogen and oral restorations with an LED light-curing unit. Elution of diurethane dimethacrylate (UDMA), Bisphenol A diglycidylether methacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) was analyzed using high-performance liquid chromatography (HPLC) 1h to 28 days post-immersion in 75% ethanol. Data were analyzed using multivariate and repeated measures analysis of variance (α = 0.05). RESULTS: The greatest elution of UDMA and BisGMA occurred from Tetric EvoCeram and the least from Filtek Z250 (p < 0.05). LED and halogen light-curing units gave similar results for all RBCs (p > 0.05) except Tetric EvoCeram which showed greater elution for the LED unit (p < 0.05). TEGDMA was below the limit of quantification. HEMA eluted in similar concentrations from Filtek Supreme and Tetric EvoCeram (p > 0.05). SIGNIFICANCE: The two nanohybrid RBCs eluted more cross-linking monomers than the ormocer and the control microhybrid RBC. Continuous elution over 28 days indicates that RBCs act as a chronic source of monomers in clinical conditions. Light source may affect monomer elution since differences were found for one out of four RBCs. Mathematical models for elution kinetics of UDMA and BisGMA indicated two elution mechanisms.

Evaluation of the light energy transmission and bottom/top rate in silorane and methacrylate-based composites with different photoactivation protocols.

AIM: This study investigated the influence of different composite resin organic matrix (methacrylate - Filtek Z350 XT and silorane - Filtek P90) on light energy transmission through the composite and bottom/top rate. MATERIALS AND METHODS: A light-emitting diode (New Blue Phase), light-curing unit was used with different photoactivation protocols (high-continuous mode - HCM, 1400 mW/cm2 for 20 seconds; low-continuous mode - LCM , 700 mW/cm2 for 40 seconds; and soft-start mode - SSM, 140 mW/cm2 for 5s followed by 39 seconds for 700 mW/cm2). Twenty specimens were prepared for each composite. The light energy transmission through the composite was calculated (n=10). The bottom/top rate of the same specimen was calculated (n=10). The data were compared by Tukey's test in different tests (light energy transmission through the composite and bottom/top rate). RESULTS: The light energy transmission through the Filtek Z350 XT composite (HCM - 576 mW/cm2, LCM - 238 mW/cm2, SSM - 232 mW/cm2) did not show statistical difference when compared with Filtek P90 composite (HCM - 572 mW/cm2, LCM - 233 mW/cm2, SSM - 230 mW/cm2). The bottom/top rate of the Filtek Z350 XT composite (HCM - 88.98%, LCM - 90.94%, SSM - 89.92%) was statistically higher than that of the Filtek P90 composite (HCM-77.29%, LCM-77.51%, SSM- 77.79%). CONCLUSION: Light energy transmission through the composite was not influenced by the use of different dental composite restoratives. However, the bottom/top rate of the composites was influenced by the use of different dental composite restoratives. CLINICAL SIGNIFICANCE: Insufficiently polymerized composite resin may present a large number of problems. For this reason, dental composite resins should have the similar deep surface polymerization as the top surface in dental restorations.

Dynamic mechanical properties of a maxillofacial silicone elastomer incorporating a ZnO additive: the effect of artificial aging.

The main objective of the current study was to investigate the dynamic mechanical properties of a room-temperature vulcanizing silicone incorporating different fractions of zinc oxide (ZnO) after indoor and outdoor photoaging. Forty-eight samples were produced by adding different amounts of ZnO into a commercial maxillofacial silicone (EPISIL-E). The samples were divided into 4 groups containing 0.0, 0.2, 0.5, and 1 wt% ZnO additive, respectively. Samples were exposed to sunlight (subgroup 2), ultraviolet (subgroup 3), and fluorescence (subgroup 4) aging, whereas nonaged samples comprised the control subgroup (subgroup 1). Dynamic mechanical analysis was used to determine the storage modulus (E'), loss modulus (E″), and damping capacity (tanδ). General linear statistic model was conducted to evaluate the effects of aging, testing frequency, and composition on the dynamic mechanical properties of the silicone with the ZnO additive. Post hoc analysis was performed using Tukey test. Statistical analysis revealed a significant impact of composition on tanδ (P < 0.05). Aging influenced E' and E″ (P < 0.01). The combination of aging and composition had a significant effect on all dynamic properties (P < 0.01).

Color and translucency in silorane-based resin composite compared to universal and nanofilled composites.

OBJECTIVES: The purpose of this study was to determine the optical properties, color and translucency, of the new silorane-based resin composite and to compare it to universal dimethacrylate-based composites. METHODS: Six dimethacrylate-based resin composites and one silorane-based resin composite (all A2 shade) were studied. Color of non-polymerized and polymerized composites was measured against white and black backgrounds using a spectroradiometer. Changes in color (ΔE*(ab)), translucency (ΔTP) and color coordinates (ΔL*, Δa* and Δb*) were calculated for each resin composite. Results were evaluated using a one-way ANOVA, a Tukey's test and a t-test. RESULTS: The polymerization-dependent ΔE*(ab) ranged from 4.7 to 9.1, with the smallest difference for the silorane-based resin composite. The color changes of silorane-based composite were due to the changes of coordinates Δa* and Δb*. However, for the dimethacrylate-based composites, the color changes mainly originated by ΔL*and Δb*. The silorane composite exhibited the smallest TP values. Tukey's test confirmed significant statistical differences (p<0.05) between mean TP values of Filtek Silorane and each brand of dimethacrylate-based composites before and after polymerization. CONCLUSIONS: The new silorane-based restorative system showed different optical properties compared to clinically successful dimethacrylate composites. The silorane composite exhibited better polymerization-dependent chromatic stability, and a lower translucency compared to other tested products.

Reversible switching of the shear modulus of photoresponsive liquid-crystalline polymers.

Manipulation makes light work: The morphology and rheological properties of a liquid-crystalline system can be dynamically manipulated with UV light by attaching photoresponsive liquid-crystalline moieties to a siloxane-based polymer. Stimulation with UV light induces a conformational change in the molecule, which disrupts the liquid-crystalline mesophase (see picture), and results in a dramatic change in its rheological properties.