Growth models of fractal interfaces in the description of microorganism colony growth: effect of photodynamic inactivation.

Candida albicans is responsible for most of the nosocomial infections that affect immunocompromised individuals. We investigated the application of eosin in photodynamic inactivation as a strategy in the inhibition of the growth of C. albicans and the morphological variation and growth dynamics in light of fractal theory. The damage caused to fungal structures alters the roughness of the colony, and these changes were described by parameters that were defined by mathematical models. Proliferation of the fungi should be inhibited in the center of the colonies and the analysis of the edges gives an indication about the dynamics of growth and cell reproduction.

Latex membranes with methylene blue dye for antimicrobial photodynamic therapy.

The search for new materials that can be applied in the treatment of injured human tissues has led to the development of new dressings. Membranes have potential as dressing materials because they can be fitted to and interact with the tissue surface. In this study, we analyze the morphological properties and wettability of latex membranes, along with the incorporation of the photosensitizer methylene blue, in the context of the utility of the membranes in curative applications involving photodynamic therapy (PDT). It was observed that deposition of the photosensitizer into latex membranes increased both the surface roughness and wettability. Antifungal testing indicated that antimicrobial PDT assisted by the latex membranes incorporating methylene blue effectively inactivated Candida albicans.

Acute BAF perturbation causes immediate changes in chromatin accessibility.

Cancer-associated, loss-of-function mutations in genes encoding subunits of the BRG1/BRM-associated factor (BAF) chromatin-remodeling complexes1-8 often cause drastic chromatin accessibility changes, especially in important regulatory regions9-19. However, it remains unknown how these changes are established over time (for example, immediate consequences or long-term adaptations), and whether they are causative for intracomplex synthetic lethalities, abrogating the formation or activity of BAF complexes9,20-24. In the present study, we use the dTAG system to induce acute degradation of BAF subunits and show that chromatin alterations are established faster than the duration of one cell cycle. Using a pharmacological inhibitor and a chemical degrader of the BAF complex ATPase subunits25,26, we show that maintaining genome accessibility requires constant ATP-dependent remodeling. Completely abolishing BAF complex function by acute degradation of a synthetic lethal subunit in a paralog-deficient background results in an almost complete loss of chromatin accessibility at BAF-controlled sites, especially also at superenhancers, providing a mechanism for intracomplex synthetic lethalities.

Alteration of Emotion Knowledge and Its Relationship with Emotion Regulation and Psychopathological Behavior in Children with Cerebral Palsy.

Emotion knowledge has not been explored in children with cerebral palsy (CP). To evaluate differences in emotion knowledge between children with CP and their typically developing peers (TDP), and explore its associations with affective regulation and behavioral psychopathology. 36 Children with CP and 45 TDP completed the Emotion Matching Task (emotion knowledge); their parents completed the Emotion Regulation Checklist and Child Behavior Checklist (emotional regulation and lability; psychopathological behaviors). Children with CP made more mistakes in emotion knowledge tasks, had lower emotional regulation and higher behavioral problems than their TDP. Emotion knowledge showed a positive correlation with emotional regulation and a negative correlation with behavioral problems, predicting psychopathological behaviors. Greater attention to emotion knowledge in children with CP could improve adjustment at social and behavioral functioning.

Genetic Variability of Ceraeochrysa cincta, Ceraeochrysa claveri, and Ceraeochrysa cubana (Neuroptera: Chrysopidae) Populations in Agroecosystems of Southeast Brazil.

The species of the genus Ceraeochrysa, known as green lacewings or trash-carriers, are widely distributed along the Americas and its islands. In Brazil, 28 species are found, including Ceraeochrysa cincta (Schneider), Ceraeochrysa claveri (Navás), and Ceraeochrysa cubana (Hagen). These species are recorded on many crops, where they are often used for biological control. For this use, knowledge of the genetic features of the species is extremely important because they are associated to the species' ability to withstand different conditions in new environments, such as variations of temperature and presence of pathogens. However, little is known about the genetic features of Ceraeochrysa species. Here, we analyze and compare the distribution of the genetic variability of C. cincta, C. claveri, and C. cubana in agroecosystem populations of southeast Brazil. We found a high genetic diversity in each of the three species, and no strong genetic structure was detected, such that genetic diversity is broadly shared among the crops and localities analyzed. We can conclude that there was a high gene flow among the sampled Ceraeochrysa populations (natural or driven by anthropic action) since the exchange of seedlings among crops can lead to the distribution of the specimens.

Fractal analysis and mathematical models for the investigation of photothermal inactivation of Candida albicans using carbon nanotubes.

Candida albicans is responsible for the majority of nosocomial infections affecting immunocompromised patients. Systemic antifungals may promote microbial resistance, which has led to the search for alternative treatments, such as photothermal therapy (PTT). PTT assumes that the interaction of electromagnetic radiation with a photothermal agent generates heat that can lead to the destruction of tumor cells and the death of microorganisms. Carbon nanotubes (CNTs) have the potential for applications in biomedical systems, including acting as controlled deliverers of drugs, biosensors and scaffolds for tissue engineering and regenerative medicine. Furthermore, the absorption of radiation by CNTs in the infrared region induces an increase in temperature, which makes CNTs candidates for photothermal agents. In this work, the photothermal inactivation of C. albicans was evaluated by multiple wall CNTs associated with laser radiation in the near-infrared region. The mechanisms that are involved in inactivation were evaluated through cell susceptibility studies and an analysis of microscopic images that are associated with mathematical models and fractal concepts. The results indicate that direct contact between the cells and CNTs without irradiation does not lead to cell death, whereas the laser-mediated process is effective in inactivation. The application of the laws of scale and fractal concepts indicate that in the control groups, there are two distinct regimes that are delimited by the mean diameter of the microorganisms, as described by the Eden model and by the quasi-Euclidean surface. For the irradiated groups, the surfaces present only one regime described by Kardar-Parisi-Zhang, KPZ. The analysis of the fractality of the system by mathematical models can help in the identification of new strategies for the inactivation of microorganisms.

Regioregularity and deposition effect on the physical/chemical properties of polythiophene derivatives films.

Polythiophene thin films are widely studied for applications in organic electronics. However, some comparisons are still missing, regarding distinct deposition techniques and regioregularity. Here regioregular and regiorandom alkyl-substituted polythiophene derivatives (P3ATs) were deposited on solid substrates using both Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques. The main goal was to verify the possible influence of the regioregularity as well the deposition technique on their optical, electrical and electrochemical properties. LB and LS films of regioregular and regiorandom poly(3-butylthiophene) (P3BT) and poly(3-octylthiophene) (P3OT) were deposited onto glass/Indium-Tin-Oxide) substrates and characterized by UV-visible optical spectroscopy, atomic force microscopy, cyclic voltammetry, and conductivity measurements. The results demonstrated the influence of the deposition technique on the electrical outcome, moreover, the regioregularity affected all the performed characterizations. In addition, this paper may be useful to understand how the amphiphilic molecule addition affected the film properties of regioregular and regiorandom P3ATs, particularly the energy diagram provided by the electrochemical and absorption features.

Preparation and characterization of epicuticular wax films.

Dipping films from epicuticular wax (EW) were prepared as model systems of epicuticular wax films found in plants. In these films, the growth uniformity, surface morphology, and hydrophobicity were examined. It was observed growth uniformity (linear growth) only from the fifth layer onwards because of the influence of substrate. The surface morphology of the films was found to be composed of pores formed by aggregates of EW molecules, both with a fractal form. An increase in the number of film layers resulted in the increase of the number of pores up to a maximum value followed by a decrease. Such increase was assigned to the growth of aggregates whereas the decrease was explained by the increase of pore sizes, because during the growth of the aggregates, the small pores are replaced by the large pores. Hydrophobicity increased with the number of layers, which was associated with the increase of irregularities on the surface caused by the pores and aggregates. In addition, it was observed that the number of pores increased with temperature. This was explained by the increase in the mobility of EW molecules, which led to a larger amount of EW molecules deposited. Based on our results and the advantages offered by dipping films - including the control of thickness and structure - this type of film is feasible as a model for studies of cuticular water transport in plants.

Mathematical models and fractal analysis for the investigation of the photodynamic inactivation in phytopathogenic microorganisms.

The increasing and indiscriminate use of pesticides may lead to the intoxication and contamination of the environment and foods. In addition, pesticides can cause fungal resistance promoting the selection of resistant phytopathogenic fungi. This is a problem in the agricultural and human health areas, which leads to a need for developing new methodologies to address this problem. Photodynamic inactivation is a promising strategy involving the association of a photosensitizer (PS), light, and molecular oxygen to inhibit the growth of microorganisms. In this work, the PS acridine orange (AO) was deposited using the spray layer-by-layer technique. The effectiveness of the method was evaluated by the analysis of the growth evolution of the colonies as a function of the amount of PS layers applied in field in the presence of sunlight. Image processing and analysis of the fractal theory were used to evaluate the growth of the colonies. The results revealed that AO is a candidate PS for use in field. It was possible to observe the reduction of the growth dynamics of the colonies with the increase of the number of PS layers. The parameters related to the fractality of the system were described by mathematical models of the fractal growth of interfaces. The knowledge of these parameters can help to identify new strategies for the control of phytopathogenic microorganisms that directly affect agricultural production.

Immobilization of triclosan and erythrosine in layer-by-layer films applied to inactivation of microorganisms.

The use of layer-by-layer (LbL) deposition technique allows materials, such as drugs, to be self-assembled in multilayers with other electrolytes by combining their properties in a nanostructured system. Triclosan (TCS) is commonly used as a drug because of its bactericidal action, while erythrosine (ERY) has been used as a photosensitizer in photodynamic therapies because of its high light absorptivity in the visible region of the electromagnetic spectrum. The major advantage of investigating systems immobilized in LbL films is the benefit of characterizing the interaction through available substances in solid state techniques. It was possible to immobilize in LbL films, ERY, and ERY + TCS. The results show that the growth of the films was linear, indicating the deposition of the same amount of material from the first bilayer without substrate interference. The release analysis showed slow kinetics, which occurred more rapidly for ERY LbL films, probably due to apparent activation energy, which were higher for films with TCS. The combination of TCS, ERY, and laser light (532 nm) for photodynamic inactivation of the fungus Candida albicans was analyzed, and the results were promising for future studies in applications, such as coating surfaces of dental implants.

Incorporation of triclosan and acridine orange into liposomes for evaluating the susceptibility of Candida albicans.

Candida albicans is responsible for many of the infections affecting immunocompromised individuals. Although most C. albicans are susceptible to antifungal drugs, uncontrolled use of these drugs has promoted the development of resistance to current antifungals. The clinical implication of resistant strains has led to the search for safer and more effective drugs as well as alternative approaches, such as controlled drug release using liposomes and photodynamic inactivation (PDI), to eliminate pathogens by combining light and photosensitizers. In this study, we used layer-by-layer (LBL) assembly to immobilize triclosan and acridine orange encapsulated in liposomes and investigated the possibility of controlled release using light. Experiments were carried out to examine the susceptibility of C. albicans to PDI. The effects of laser irradiation were investigated by fluorescence microscopy, atomic force microscopy, and release kinetics. Liposomes were successfully prepared and immobilized using the self-assembly LBL technique. Triclosan was released more quickly when the LBL film was irradiated. The release rate was approximately 40% higher in irradiated films (fluence of 15J/cm2) than in non-irradiated films. The results of the susceptibility experiments and surface morphological analysis indicated that C. albicans cell death is caused by photodynamic inactivation. Liposomes containing triclosan and acridine orange may be useful for inactivating C. albicans using light. Our results lay the foundation for the development of new clinical strategies to control resistant strains.

Immobilization of chlorophyll by using layer-by-layer technique for controlled release systems and photodynamic inactivation.

The development of systems for the controlled release of drugs is important because they allow the control of drug absorption and tissue distribution and also can reduce local toxicity. This study aimed to assemble and characterize two types of release systems, consisting of layer-by-layer films obtained from poly(allylamine) hydrochloride with chlorophyll (PAH/CHL films) or chlorophyll incorporated into dipalmitoylphosphatidylcholine liposomes (PAH/Lip+CHL films). For these systems, the molecular aggregation, growth process, thermally stimulated desorption, wettability, and controlling release of CHL was studied by using UV-vis spectroscopy and wetting contact angle analysis. In addition, experiments of photodynamic inactivation using PAH/CHL or PAH/Lip+CHL films with a 633-nm laser light were performed and the susceptibility of Candida albicans (C. albicans) to this approach was examined. Fluorescence and atomic force microscopies were used to investigate the surface morphology after the application of the photoinactivation procedure. A redshift of the UV-vis spectrum associated to films when compared with the spectrum of the CHL solution indicated a molecular aggregation of CHL molecules in the films. The film growth process was determined by a nucleation and a growth of spheroids or rods for either PAH/Lip+CHL or PAH/CHL films, respectively. Thermally activated desorption experiments indicated that interactions between CHL and PAH (126kJ/mol) in PAH/CHL or between Lip+CHL and PAH (140kJ/mol) in PAH/Lip+CHL films may be governed by electrostatic interactions. The wettability of PAH/Lip+CHL films was larger than that for PAH/CHL films, which can be attributed to hydrophilic groups on the surface of the DPPC liposomes. Release experiments revealed that free CHL in PAH/CHL films was released more slowly than its partner incorporated into liposomes. After the photodynamic inactivation, results of survival fraction and fluorescence microscopy revealed that C. albicans presented similar susceptibility for the two kinds of films. AFM supported the fluorescence one suggesting that cell death of C. albicans may occur due to damages to its cell wall by C. albicans.

Spray layer-by-layer films for photodynamic inactivation.

BACKGROUND: A novel approach for photodynamic inactivation of Candida albicans is proposed. This method consists of realizing inactivation using ultraviolet light (254nm) combined with spraying layer-by-layer films of acridine orange. METHODS: To evaluate the effectiveness of the approach, the C. albicans were immobilized on quartz slices and covered with the spray layer-by-layer films. The fungi were analyzed using experiments to determine cell viability, as well as by fluorescence and atomic force microscopy. RESULTS: Viability analysis of C. albicans after photodynamic inactivation assisted by the films indicates cell death. The extent of cell death increases as the number of film layers increases. Fluorescence and atomic force microscopy analyses corroborated the cell death of C. albicans, which is posited to be due to damages to the fungi cell wall. CONCLUSIONS: Our approach has the potential to be used as an alternative for photodynamic inactivation of C. albicans. In addition, this method could be used in clinical procedures, such as for the decontamination of medical devices.

Morphological alterations on Citrobacter freundii bacteria induced by erythrosine dye and laser light.

The effect of the laser irradiation (532 nm) on films prepared from Citrobacter freundii mixed with erythrosine dye was investigated by using atomic force microscopy. It was observed that morphological changes of bacterial surfaces after irradiations, which were attributed to cellular damage of the outer membranes, are a result of a photodynamic effect. The results suggested that the combination of erythrosine and laser light at 532 nm could be a candidate to a photodynamic therapy against C. freundii.

Morphological analysis and interaction of chlorophyll and BSA.

Interactions between proteins and drugs, which can lead to formation of stable drug-protein complexes, have important implications on several processes related to human health. These interactions can affect, for instance, free concentration, biological activity, and metabolism of the drugs in the blood stream. Here, we report on the UV-Visible spectroscopic investigation on the interaction of bovine serum albumin (BSA) with chlorophyll (Chl) in aqueous solution under physiological conditions. Binding constants at different temperatures--obtained by using the Benesi-Hildebrand equation--were found to be of the same order of magnitude (~10(4)M(-1)) indicating low affinity of Chl with BSA. We have found a hyperchromism, which suggested an interaction between BSA and Chl occurring through conformational changes of BSA caused by exposition of tryptophan to solvent. Films from BSA and Chl obtained at different Chl concentrations showed fractal structures, which were characterized by fractal dimension calculated from microscopic image analysis.

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene. Green lacewings are generalist predators, and the species Chrysoperla externa presents a great potential for use in biological control of agricultural pests due to its high predation and reproduction capacities, as well as its easy mass rearing in the laboratory. The adaptive success of a species is related to genetic variability, so that population genetic studies are extremely important in order to maximize success of the biological control. Thus, the present study used nuclear (Inter Simple Sequence Repeat - ISSR) and mitochondrial (Cytochrome Oxidase I - COI) molecular markers to estimate the genetic variability of 12 populations in the São Paulo State, Brazil, as well as the genetic relationships between populations. High levels of genetic diversity were observed for both markers, and the highest values of genetic diversity appear associated with municipalities that have the greatest areas of native vegetation. There was high haplotype sharing, and there was no correlation between the markers and the geographic distribution of the populations. The AMOVA indicated absence of genetic structure for the COI gene, suggesting that the sampled areas formed a single population unit. However, the great genetic differentiation among populations showed by ISSR demonstrates that these have been under differentiation after their expansion or may also reflect distinct dispersal behavior between males and females.

Immunosensor for HIV-1 diagnostics based on immobilization of the antigenic peptide p24-3 into liposomes.

In this work we developed an immunosensor for HIV-1 diagnostics that exploits the biorecognition between the antibody anti-p24 and the antigenic peptide p24-3 (AMATLRAEQASQEVKNWMTETL- LVQNA) derived from the HIV-1 p24 protein. p24-3 was encapsulated in phospholipid liposomes and immobilized in layer-by-layer (LbL) films produced with polyethyleneimine (PEI). The incorporation of p24-3 into liposomes was investigated using circular dichroism (CD) spectroscopy, from which an increase in the alpha helix conformation could be noted. The maximum fluorescence emission for p24-3 occurred at 340 nm in solution, compatible with the tryptophan residue being exposed to the solvent, and at 335 and 322 nm when in liposomes and PEI/p24-3-liposome LbL films, respectively. This blue shift is consistent with the tryptophan being in a partially buried environment. With the preserved structure in the LbL films, p24-3 could recognize the anti-p24 antibody in impedance spectroscopy measurements. Therefore, LbL films containing p24-3 may be suitable for detecting HIV-1 in a low-cost, easy-to-use immunosensing assay.

Photoresponsive wettability in monolayer films from sinapinic acid.

Sinapinic acid is an interesting material because it is both antioxidant and antibacterial agent. In addition, when illuminated with ultraviolet light, it can exhibit the so-called photodimerization process. In this paper, we report on the investigation of monolayer films from 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid, SinA) deposited onto poly(allylamine hydrochloride), PAH, films. SinA monolayers were prepared by using the layer-by-layer (LbL) self-assembly technique. Adsorption kinetics curves were well fitted by a biexponential function suggesting that the adsorption process is determined by two mechanisms: nucleation and growth of aggregates. By using wetting contact angle analysis, we have found that SinA monolayers exhibit photoresponsive wettability under UV irradiation (365 nm); that is, wettability decreases with increasing UV irradiation time. The photoresponse of wettability was attributed to photodimerization process. This hypothesis was supported by the dependence of surface morphological structure and absorption on UV irradiation time. The mechanism found in the well-known transcinnamic acid crystals is used to explain the photodimerization process in SinA monolayers.

Phase diagram of a cyclic predator-prey model with neutral-pair exchange.

In this paper we obtain the phase diagram of a four-species predator-prey lattice model by using the proposed gradient method. We consider cyclic transitions between consecutive states, representing invasion or predation, and allowed the exchange between neighboring neutral pairs. By applying a gradient in the invasion rate parameter one can see, in the same simulation, the presence of two symmetric absorbing phases, composed by neutral pairs, and an active phase that includes all four species. In this sense, the study of a single-valued interface and its fluctuations give the critical point of the irreversible phase transition and the corresponding universality classes. Also, the consideration of a multivalued interface and its fluctuations bring the percolation threshold. We show that the model presents two lines of irreversible first-order phase transition between the two absorbing phases and the active phase. Depending on the value of the system parameters, these lines can converge into a triple point, which is the beginning of a first-order irreversible line between the two absorbing phases, or end in two critical points belonging to the directed percolation universality class. Standard simulations for some characteristic values of the parameters confirm the order of the transitions as determined by the gradient method. Besides, below the triple point the model presents two standard percolation lines in the active phase and above a first-order percolation transition as already found in other similar models.