Antimicrobial activity of Er, Cr: YSGG and Ultrasonic on E. faecalisbiofilm in the mesial root canal systems of lower molars / Atividade antimicrobiana de Er, Cr: YSGG e Ultrassônico no biofilme de E. faecalis nos sistemas de canais radiculares mesiais de molares inferiores

The internal topography of the root canal is complex, especially for the permanent molar's mesial root. In response to such issues, improved irrigation techniques have been created, which use laser pulses to agitate fluids and improve microbial deposit removal. Objective: To assess the effectiveness of the Er,Cr:YSGG laser with a wavelength of 2,780 nm via photon-induced photoacoustic streaming (PIPS) protocol which agitated of 2% chlorohexidine (CHX) in removing mature Enterococcus faecalis (E. faecalis) biofilm in root canal systems of lower molars. Material and Methods: The mesial roots of lower first and second molars were separated and inoculated with E. faecalis bacterial suspension for 30 days. The roots were irrigated with CHX, some of them were agitated with a passive ultrasonic device (PUI), while the other roots were agitated by an Er,Cr:YSGG laser in PIPS at 60 µs/pulse, 5 Hz, (0.25, 0.5, 0.75, and 1) W. An atomic force microscope (AFM) was used as a new method to get the results in the isthmus area; the obtained results from each group were compared with each other. Results: Based on the AFM and SEM analyses, laser and ultrasonic activation groups showed higher antimicrobial efficacy than the conventional syringe irrigation group (P<0.05). Conclusion: Based on the investigation's findings, the activation of 2% CHX solution by Er,Cr:YSGG laser in PIPS and PUI offers better mature bacterial biofilm removal in the mesial root of lower human molars than the same irrigant with the SI technique (AU)

A topografia interna do canal radicular é complexa, especialmente para a raiz mesial do molar permanente. Em resposta a esses problemas, foram criadas técnicas aprimoradas de irrigação, que utilizam pulsos de laser para agitar fluidos e melhorar a remoção de depósitos microbianos. Objetivo: Avaliar a eficácia do laser Er,Cr:YSGG com comprimento de onda de 2.780 nm via protocolo de streaming fotoacústico induzido por fótons (PIPS) que agitou clorohexidina a 2% (CHX) na remoção de Enterococcus faecalis maduro (E. faecalis) biofilme em sistemas de canais radiculares de molares inferiores. Material e Métodos: As raízes mesiais de 28 primeiros e segundos molares inferiores foram separadas e inoculadas com suspensão bacteriana de E. faecalis por 30 dias. As raízes foram irrigadas com CHX, sendo algumas delas agitadas com aparelho ultrassônico passivo (PUI), enquanto as demais raízes foram agitadas com laser Er,Cr:YSGG em PIPS a 60 µs/pulso, 5 Hz (0,25, 0,5, 0,75 e 1) W. Um microscópio de força atômica (AFM) foi utilizado como um novo método para obter os resultados na área do istmo; os resultados obtidos de cada grupo foram comparados entre si. Resultados: Com base nas análises de AFM e SEM, os grupos de ativação por laser e ultrassom apresentaram maior eficácia antimicrobiana do que o grupo de irrigação com seringa convencional (P<0.05). Conclusão: Com base nos achados da investigação, a ativação da solução de CHX a 2% pelo laser Er,Cr:YSGG em PIPS a (60 µs/pulso, 5 Hz, 0,75 W) oferece melhor remoção de biofilme (AU)

Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

Application of atomic force microscope in the study of enamel with dental fluorosis / 中华地方病学杂志

At present, the exact pathogenesis of dental fluorosis is not clear, and there is no exact standard of enamel acid etching in the adhesive restoration of dental fluorosis. Atomic force microscope represents a great progress in high-resolution imaging of biomaterials, and its advantage is that it can provide three-dimensional images and quantitative data of observed samples at the nanometer level. In recent years, the application of atomic force microscope in enamel study has made some progress. Whether the quantitative analysis of enamel ultrastructure can become a new way to study the pathogenesis of dental fluorosis and find the best repair method is worthy of further exploration. This paper reviews the application of atomic force microscope in the study of enamel with dental fluorosis.

Microscopic morphology observation of fracture healing process promoted by panax notoginseng saponins / Observación microscópica de la morfología del proceso de curación de fracturas promovida por panax notoginseng saponins

SUMMARY: The aim of this study was to explore promoting effect of external applying Panax Notoginseng Saponins (PNS) on fractures. For this analysis 18 New Zealand male rabbits were divided into control group, splintage group and PNS group. All rabbits were performed left radius fractures and natural healing, splintage healing and splintage coated with PNS healing. 2 rabbits in each group were sacrificed on day 14, day 28 and day 42 after surgery, separately. Atomic force microscope scanning and nanoindentation tests were performed on the callus sections. The particle size and roughness in PNS group was both less than that in splintage group. The elastic modulus of callus in PNS group was consistent with normal bone tissue started from day 28 after surgery, two weeks earlier than that in splintage group. PNS could significantly reduce fracture healing time and increase strength of callus.

RESUMEN: El objetivo de este estudio fue evaluar el efecto de la aplicación externa de Panax Notoginseng Saponins (PNS) en fracturas óseas. Se usaron 18 conejos machos de raza Nueva Zelanda divididos en grupos control, entablillado y PNS. Se realizaron fracturas del radio izquierdo y cicatrización natural en todos los animales, además de la cicatrización con entablillado y entablillado recubierto con PNS. Se sacrificaron, posterior a la cirugía, dos conejos de cada grupo los día 14, 28 y 42. Se realizaron pruebas de escaneo con microscopio de fuerza atómica y nanoindentación en las secciones de callos. El tamaño de la partícula y la rugosidad en el grupo de PNS fue menor que en el grupo entablillado. El módulo elástico del callo en el grupo de PNS fue consistente con el tejido óseo normal iniciado el día 28 después de la cirugía, dos semanas antes que en el grupo de entablillado. El PNS podría redu- cir significativamente el tiempo de curación de la fractura y aumentar la fuerza del callo.

Comparative Evaluation of Surface Roughness of Resin- Modified Glass Ionomer and Glass Hybrid Restorative Materials Simulated by Tooth Brushing: An in-Vitro Study

ABSTRACT Objective: Tocompare the effect of tooth brushing on surface roughness of Resin-Modified Glass Ionomer Cement (RMGIC; GC Gold label 2LC Light Cured Universal Restorative) and Glass Hybrid (GH; GC EQUIA SYSTEM- EQUIA Forte™ Fil and EQUIA Forte™ Coat) restorative material at 1- and 3-months interval simulated by tooth brushing. Material and Methods: RMGIC and GH material specimens (20 each) were prepared according to manufacturer instructions in 10mm × 2 mm dimensions using a mylar strip. A specially designed toothbrush simulator was used along with Oral B Pro 2 2000N powered toothbrush and Colgate Total dentifrice (Colgate-Palmolive India limited; Relative dentin abrasivity - RDA:70- Low abrasive) to perform brushing strokes. Specimens were subjected to surface roughness analysis before and after simulated tooth brushing at baseline, 1, and 3 months. Results: The intragroup comparison was done using repeated-measures ANOVA. Intergroup comparisons were done using an independent sample t-test and General Linear Model (ANCOVA). Surface roughness increased from baseline through 3 months in both RMGIC and GH groups. The mean surface roughness in RMGIC group was significantly higher than GH group at baseline 1 and 3-months, respectively (p<0.001, <0.001, and <0.001). Interaction between group and baseline surface roughness was not significant (p=0.466). The estimated marginal means were significantly higher in RMGIC than GH group (p=0.008). Conclusion: The surface roughness of both RMGIC and GH restorative increased from baseline to 1 month and 3 months after the simulated toothbrushing protocol. GH exhibited significantly lower surface roughness than RMGIC at all the tested intervals.

Hardness Properties of Pig Esophageal at Nanoscale Using Atomic Force Microscope / 医用生物力学

Objective To study the hardness properties of pig esophageal at the nanoscale using atomic force microscope (AFM). Methods The porcine esophagus was chosen as experimental sample to study the hardness properties of esophageal tissues at different loading rates, deflection and dwell time with AFM. Results The hardness of esophageal tissues at the nanoscale was strongly correlated with the loading rate and the deflection, which increased with the increasing loading rate and decreased with the increasing deflection of cantilever. The difference in the hardness was associated with the viscoelasticity and viscoplasticity of esophageal tissues, including contact stress, energy transition and strain plastic gradient. Conclusions The experimental results have important significance for clinical diagnosis, surgical operation and artificial material development, and reveal the changing patterns for mechanical properties of the esophageal tissues at the microscale.

Research progress on the methods of observation and analysis of dental bonding interfaces / 口腔疾病防治

@#Dental bonding technology and materials have been used widely in dentistry because of their excellent properties. The development of novel bonding technology and materials is constantly being performed to improve the effect of dental bonding restorations. Observation and analysis of the dental bonding interface is one of the most important methods for laboratory evaluation of bonding efficiency. This paper aims to review the methods of observation and analysis of dental bonding interfaces to provide a reference for the selection of evaluation methods in dental bonding research. The features of 6 methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Raman spectroscopy (RS), optical coherence tomography (OCT) and atomic force microscopy (AFM), were described and summarized. Among these methods, SEM and TEM are used most often in the analysis of fine structures; CLSM and OCT are used for the acquisition of characteristic image signals, such as microleakage and exogenous and endogenous fluorescence; and RS and AFM can test chemical composition and mechanical properties.

Effects of graphene on the proliferation, migration and morphology of dental pulp stem cells / 口腔疾病防治

Objective@# To investigate the effects of graphene on the proliferation, migration and cell morphology of dental pulp stem cells (DPSCs).@*Methods@#Graphene powder was prepared by the oxidation-reduction method, and a 0.5 mg/mL graphene dispersion was prepared. Raman spectroscopy and atomic force microscopy were used to characterize the structure and surface morphology of graphene. DPSCs were isolated and cultured in vitro. MTT assay was used to detect the effects of different concentrations of graphene dispersions (0, 1, 5, 10, 20, 50, 100 μg/mL) on the proliferation and wound healing assay was used to detected the migration abilities of DPSCs. The effects of graphene on the morphology of DPSCs were observed by immunofluorescence staining. @*Results @# In the present study, compared with the control group (0 μg/mL), the proliferation of DPSCs in the 100 μg/mL group was inhibited at 72 h (P < 0.05), and the proliferation of DPSCs in the other groups was not significantly affected (P > 0.05). Graphene dispersions at 10 and 20 μg/mL promoted the migration of DPSCs (P < 0.05). After being cultured in 20 μg/mL graphene dispersions for 3 days, the DPSCs showed a large and orderly cytoskeletal structure, and the spread area of cells was not significantly different from that of the control group (0 μg/mL) (P > 0.05), while some cells had the morphological characteristics of nerve cells.@* Conclusion @# Graphene has good biocompatibility and is expected to be a suitable material for tissue engineering within fitting concentration.

Applications of atomic force microscopy in immunology / 医学前沿

Cellular mechanics, a major regulating factor of cellular architecture and biological functions, responds to intrinsic stresses and extrinsic forces exerted by other cells and the extracellular matrix in the microenvironment. Cellular mechanics also acts as a fundamental mediator in complicated immune responses, such as cell migration, immune cell activation, and pathogen clearance. The principle of atomic force microscopy (AFM) and its three running modes are introduced for the mechanical characterization of living cells. The peak force tapping mode provides the most delicate and desirable virtues to collect high-resolution images of morphology and force curves. For a concrete description of AFM capabilities, three AFM applications are discussed. These applications include the dynamic progress of a neutrophil-extracellular-trap release by neutrophils, the immunological functions of macrophages, and the membrane pore formation mediated by perforin, streptolysin O, gasdermin D, or membrane attack complex.

The effect of ionizing radiation on properties of fluoride-releasing restorative materials

Abstract The purpose of this study was to evaluate the effect of ionizing radiation from high energy X-ray on fluoride release, surface roughness, flexural strength, and surface chemical composition of the materials. The study groups comprised five different restorative materials: Beautifil II, GCP Glass Fill, Amalgomer CR, Zirconomer, and Fuji IX GP. Twenty disk-shaped specimens (8x2 mm) for fluoride release and 20 bar-shaped specimens (25 x 2x 2 mm) for flexural strength were prepared from each material. Each material group was divided into two subgroups: irradiated (IR) and non-irradiated (Non-IR). The specimens from IR groups were irradiated with 1.8 Gy/day for 39 days (total IR = 70.2 Gy). The amount of fluoride released into deionized water was measured using a fluoride ion-selective electrode and ion analyzer after 24 hours and on days 2, 3, 7, 15, 21, 28, 35, and 39 (n = 10). The flexural strength was evaluated using the three-point bending test (n = 10). After the period of measurement of fluoride release, seven specimens (n = 7) from each group were randomly selected to evaluate surface roughness using AFM and one specimen was randomly selected for the SEM and EDS analyses. Data were analyzed with two-way ANOVA and Tukey tests (p = 0.05). The irradiation significantly increased fluoride release and surface roughness for Amalgomer CR and Zirconomer groups (p < 0.05). No significant change in flexural strength of the materials was observed after irradiation (p > 0.05). The ionizing radiation altered the amount of fluoride release and surface roughness of only Amalgomer CR and Zirconomer. The effect could be related to the chemical compositions of materials.

Micro and nanocrystalline cellulose based oral dispersible film; preparation and evaluation of in vitro/in vivo rapid release studies for donepezil

Oral fast-dispersible film was prepared by utlizing donepezil hydrochloride (drug) and various cellulose derivatives such as hydroxypropyl methyl cellulose (hypermellose) (HPMC), microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) to treat Alzheimer's disease. NCC was synthesized by ultra-sonication method using MCC and this was converted to thinfilm formulation (NCC-F) using solvent casting technique. The interaction between the polymer and the drug was investigated by spectral analysis such as UV, FTIR, and 1H- NMR. FTIR confirmed that the compatibility of drug and polymer in ODF formulation. NCC-F has shown an average surface roughness of 77.04 nm from AFM and the average particle size of 300 nm from SEM analysis. Nano sized particle of NCC-F leads faster in vitro dissolution rate (94.53%) when compared with MCC-F and F3 formulation. Animal model (in vivo) studies of NCC-F formulation has reached peak plasma concentration (Cmax) up to 19.018 ng/mL in the span of (tmax) 4 h with greater relative bioavailability of 143.1%. These results suggested that high surface roughness with nanosized NCC-F formulation attained extended drug availability up to (t1/2) 70 h.

Effects of different toothpastes on the prevention of erosion in composite resin and glass ionomer cement enamel and dentin restorations

Abstract Objective This study aimed to evaluate the effects of different toothpastes on the surface wear of enamel, dentin, composite resin (CR), and resin-modified glass ionomer cement (RMGIC), and to perform a topographic analysis of the surfaces, based on representative images generated by atomic force microscopy (AFM) after erosion-abrasion cycles. Methodology One hundred and forty bovine incisors were collected and divided into two groups: 72 enamel and 72 dentin blocks (4×4 mm). Half of the specimens were restored with CR (Filtek Z350 XT) and the other half with RMGIC (Fuji II LC). Then, samples were submitted to a demineralization cycle (5 days, 4×2 min/day, 1% citric acid, pH 3.2) and exposed to three different toothpastes (2×15 s/day): without fluoride (WF, n=12), sodium fluoride-based (NaF, n=12), and stannous fluoride-based (SnF2, n=12). Surface wear, as well as restoration interfaces wear, were investigated by profilometry of the dental substrates and restorative materials. All representative surfaces underwent AFM analysis. Data were analyzed by two-way analysis of variance and Tukey's tests (α=0.05). Results NaF-based toothpaste caused the greater dentin surface wear (p<0.05). Toothpastes affected only enamel-restoration interfaces. AFM analysis showed precipitate formation in dentinal tubules caused by the use of fluoride toothpastes. Conclusions NaF-based toothpastes had no protective effect on enamel adjacent to CR and RMGIC against erosion-abrasion challenges, nor on dentin adjacent to RMGIC material. SnF2-based toothpastes caused more damage to interfaces between enamel and RMGIC.

Effects of High-Fat Diet on Rat Aortic Endothelial Cell Morphology and Stiffness / 医用生物力学

Objective To investigate the high-fat diet effect on morphology and stiffness of endothelial cells. Methods SD rats were randomly divided into high-fat diet group (AS group, n=3) and control group (CON group, n=3). Rat aortic endothelial cells were obtained from rat thoracic aorta by explant method. Cell morphology was observed under inverted microscopy. The mean fluorescent intensity of F-actin in two groups was calculated by immunofluorescence staining. Cell stiffness was measured by atomic force microscopy (AFM). Results The endothelial cells migrated from tissue plant on the 7th day and formed confluence after cultivation for 14 days. Endothelial cells were identified by factor Ⅷ immunofluorescence staining. Cells in AS group showed enhanced perimeter (P＜0.01), aspect ratio (P＜0.01), and area (P＞0.05), while less circularity (P＜0.01) compared with the cells in control group. The mean fluorescence intensity of F-actin in AS group was significantly higher than that in control group (P＜0.01). AFM showed that the cell stiffness of AS group was significantly higher than that of control group (P＜0.01). Conclusions High-fat diet would change the morphology and stiffness of endothelial cells, which might subsequently affect their normal function and become an important incentive to AS.

Mechanical properties and cytoskeletal protein changes after anln deficiency / 中国组织工程研究

BACKGROUND: To date, ANLN has definite roles in altering cell shape, regulating cell-cell junction integrity in interphase and stabilizing actomyosin contractile rings in cytokinesis, but its effects on cell mechanical properties and on cytoskeletal proteins have rarely been reported. OBJECTIVE: To investigate the effect of ANLN deletion on the mechanical properties and cytoskeleton of interphase Hela cells. METHODS: Surface elastic modulus and membrane rupture force of normal untreated Hela cells and ANLN RNA stably knocked down Hela cells were measured by atomic force microscopy. We screened for the cells that stably expressed mCherry-Myosin II A, and observed the distribution characteristics of cytoskeletal proteins by laser scanning confocal microscopy. RESULTS AND CONCLUSION: (1) The elastic modulus of Hela cells with ANLN stably knocked down was significantly higher than that of normal Hela cells, and the elastic modulus of normal cells were more prone to polar distribution (gradually decreasing between the two poles) than that of ANLN knockdown Hela cells. However, there was no significant difference in the membrane rupture force at the long-axis edge region between the two groups. (2) Myosin IIA lowly expressed in the marginal region of ANLN knockdown cells. (3) The actin fibers tended to be scattered in the near-bottom cell-cell junction region of the ANLN knockdown group, and there were no obvious intracellular fibers bundles arranging along the long axis. The cell gap tended to enlarge in the middle layer. To conclude, ANLN knockdown cells have the greatest impact in the marginal region, the deficiency of ANLN leads to a more frequent remodeling in the cell marginal region, and the cells need to accumulate more cytoskeletal proteins and binding proteins to stabilize the cell state, resulting in higher modulus of elastics.

Structure and mechanical properties of high- and low-weight-bearing areas of hip cartilage at micro and nano levels / 中国组织工程研究

BACKGROUND: Articular cartilage has a high-weight-bearing area and a low-weight-bearing area. There are different macroscopic elastic moduli in the two regions, but the modulus of the two areas at the micro and nano levels is unknown. Such information is important for further understanding of cartilage micro and nano mechanics. Moreover, the micro and nano structures of the two areas, which influence the cartilage mechanical properties, should be discussed. OBJECTIVE: To investigate the mechanical properties and structure of high- and low-weight-bearing areas of the hip articular cartilage at the micro and nano levels. METHODS: Normal porcine femoral head cartilage was used. Atomic force microscopy with a spherical tip of 5 µm in diameter was used to measure the microscale compressive elastic modulus of different weight-bearing areas of the cartilage. The nanoscale compressive elastic modulus, nano structure, and collagen fiber diameter were measured using a ScanAsyst-Air probe with a radius of curvature of 5 nm. Scanning electron microscopy was employed to identify the microstructure of different weight-bearing areas of the cartilage. RESULTS AND CONCLUSION: The microscale elastic modulus of the high-weight-bearing area of the femoral head cartilage was (433.05±146.52) kPa, and the microscale elastic modulus of the low-weight-bearing area was (331.19±84.88) kPa. The nanoscale elastic modulus of the high- and low-weight-bearing areas of the femoral head cartilage was (1.24±0.42) GPa and (1.28±0.41) GPa, respectively. While no statistically significant differences were found in the elastic modulus of collagen fibers at the nano level (P=0.846 2). The collagen fibers of the high-weight-bearing area arranged more regularly than those of the low-weight-bearing area at the micro level. No significant differences between collagen fiber diameter of the two areas at the nano level were observed (P=0.926 4). To conclude, the collagen fibers of the high-weight-bearing area are cross-linked more regularly than those of low-weight-bearing area. Therefore, the compressive elastic modulus of the high-weight-bearing area at the micro level is significantly higher than that of the low-weight-bearing area, which is consistent with the macroscopic compressive elastic modulus trend. However, high-weight-bearing has no impact on individual collagen fibers at the nano level.

Interfacial properties and micellization of triblock poly(ethylene glycol)-poly(-caprolactone)-polyethyleneimine copolymers

This study aimed to explore the link between block copolymers' interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system. A library of diblock copolymers of PEG-PCL and triblock copolymers with additional PEI (PEG-PCL-PEI) were synthesized. Subsequently, a systematic isothermal investigation was performed to explore molecular arrangements of copolymers at air/water interface. Then, structural properties and drug encapsulation in self-assembly were investigated with DLS, SLS and TEM. We found the additional hydrogen bond in the PEG-PCL-PEI contributes to film stability upon the hydrophobic interaction compared with PEG-PCL. PEG-PCL-PEI assemble into smaller micelle-like (such as PEG-PCL4006-PEI) or particle-like structure (such as PEG-PCL8636-PEI) determined by their hydrophilic and hydrophobic block ratio. The distinct structural architectures of copolymer are consistent between interface and self-assembly. Despite the disparity of constituent ratio, we discovered the arrangement of both chains guarantees balanced hydrophilic-hydrophobic ratio in self-assembly to form stable construction. Meanwhile, the structural differences were found to have significant influence on model drugs incorporation including docetaxel and siRNA. Taken together, these findings indicate the correlation between molecular arrangement and self-assembly and inspire us to tune block compositions to achieve desired nanostructure and drug loading.

Effect of lactobacillus postbiotics on entamoeba histolytica trophozoites

ABSTRACT Background Amebiasis is an infectious disease caused by Entamoeba histolytica. It represents one of the three worldwide leading causes of death by parasites and a public health problem due to its frequency, morbidity, mortality, and easy dispersion. Objective The study was aimed to evaluate the in vitro effect of Lactobacillus spp. postbiotics on E. histolytica trophozoites (HM1-IMSS strain) and to determine morphometric changes in trophozoite membrane by atomic force microscopy (AFM). Methods Bioassays on trophozoites were conducted with lyophilized postbiotics at 0.1, 0.3, and 0.5 mg/mL concentrations, and trophozoite samples were obtained for AFM analysis Results Results indicated postbiotic inhibitory activity; the highest percentage inhibition was 89.63% at 0.5 mg/mL. Trophozoites nanomechanical analysis showed 28.32% increase in ruggedness and 56% decrease in size with treatments compared to the control. Conclusion Our study showed that the synergy of Lactobacillus postbiotics inhibited E. histolytica HM1-IMSS in vitro growth under axenic conditions, inducing morphometric alterations in trophozoites’ cell membrane. These results would allow designing strategies or treatments aimed at E. histolytica control in the future.

Using prodigiosin against some gram-positive and gram-negative bacteria and Trypanosoma cruzi

This work aimed to explore the action of natural prodigiosin on both bacterial organisms and Trypanosoma cruzi cells. Methods: Natural prodigiosin pigment was extracted and purified from cultures of Serratia marcescens. Two media, peanut broth and peptone glycerol broth, both recommended in the literature for prodigiosin production, were compared. The prodigiosin obtained was employed to explore its antimicrobial properties against both bacteria and Trypanosoma cruzi cells. Results: Peanut broth yielded four times more prodigiosin. The prodigiosin showed remarkable activity (minimal inhibitory concentrations in the range of 2-8 µM for bacteria and half maximal inhibitory concentration of 0.6 µM for Trypanosoma cruzi). In fact, the prodigiosin concentration required to inhibit parasite growth was as low as 0.25 mg/l versus 4.9 mg/l of benznidazole required. Furthermore, atomic force microscopy revealed marked morphological alterations in treated epimastigote forms, although no pore-formation activity was detected in protein-free environments. Conclusions: This work demonstrates the potential usefulness of prodigiosin against some gram-positive and gram-negative bacteria and Trypanosoma cruzi although further studies must be done in order to assess its value as a candidate molecule.(AU)

Surface morphologic evaluation of orthodontic bonding systems under conditions of cariogenic challenge

Abstract: Orthodontic bonding systems are submitted to demineralization and remineralization dynamics that might compromise their surface smoothness, and favor biofilm aggregation and caries development. The aim of the present study was to evaluate the effects of a cariogenic challenge model (in vitro pH-cycling model) on the surface roughness and topography of 3 bonding materials: Transbond™ XT (XT), Transbond™ Plus Color Change (PLUS) and Fuji Ortho™ LC (FUJI), by means of Atomic Force Microscopy (AFM). Six specimens with standardized dimensions and surface smoothness were fabricated per group, and the materials were manipulated in accordance with the manufacturers' instructions. No polishing was necessary. AFM tests were performed before and after pH-cycling, taking 3 readouts per specimen. The roughness results (Ra) were obtained at nanometric levels (nm) and surface records were acquired in two- and three-dimensional images of height and lock-in phase of the material components. The surfaces of all groups analyzed in the study were morphologically altered, presenting images suggestive of matrix degradation and loss of matrix-load integrity. FUJI presented the greatest increase in surface roughness, followed by XT and PLUS, respectively (p≤0.001). Nevertheless, the roughness values found did not present sufficient degradation to harbor bacteria. The surface roughness of all tested materials was increased by pH-cycling. The use of materials capable of resisting degradation in the oral environment is recommended, in order to conserve their integrity and of the surrounding tissues.

In vitro biological activities of silver nanoparticles synthesized from Scedosporium sp. isolated from soil

One of the important fields in nanotechnology is the development of an environment friendly method for the synthesis of nanoparticles. Many approaches show that microorganisms are the most reliable tools for biosynthesis of nanoparticles compared to physical and chemical methods. In our study, fungi have been exploited for extracellular production of metal nanoparticles. It was observed that in Scedosporium, silver ions are reduced to silver nanoparticles, which was confirmed by UV-visible spectrophotometry and AFM. Optimization studies showed that as the concentration of AgNO3 used for synthesis increased, particles' size also increased. Size of the particles at different concentrations of AgNO3 was observed to be 79-107 nm with particles being ellipsoidal to spherical in shape. Silver nanoparticles synthesized from 2.0 mM silver nitrate, showed maximum antimicrobial activity compared to all antibiotics tested including synergistic effects. In vitro cytotoxicity of silver nanoparticles against MCF 7 and PC 3 showed that as the concentration of silver nanoparticles increased, a decrease in the percentage cell viability was observed with IC50 values being 60.09 and 57.43 µg/ml respectively. Therefore, through this study, it could be said that extracellular synthesis of silver nanoparticles from Scedosporium was simple, ecofriendly, proving excellent antimicrobial and anticancer agents.