RESUMO
Immobilizarion of PGPR for agricultural applications aims to provide temporary physical protection from stressful environmental conditions and the gradual release of cells for successful root colonization, release the cells gradually. In this work, we immobilized Bradyrhizobium sp. SEMIA6144 or Azospirillum brasilense Az39 cells in 2% alginate beads prepared by ionic gelation process, and then stored up to 12 months at 4 °C. Alginate matrix showed interaction with the immobilized bacteria (FTIR), allowed a constant release of cells, and improved their viability and capability to interact with Arachis hypogaea. Cell number into beads reached 107 CFU.bead-1; however, viability decreased from 4 months of storage for Az39, while it was maintained up to 12 months for SEMIA6144, showing a low metabolic activity measured by the MTT assay. Adhesion of SEMIA6144 and Az39 from new beads to peanut root was 11.5% and 16%, respectively, higher than non-immobilized bacteria. Peanut inoculation with 12 months storage SEMIA6144 beads significantly increased root length and biomass at 30 days of growth, and under restrictive water condition (RWC), nodulation and total plant N content increased compared with liquid inoculation. Our results demonstrate that immobilization of SEMIA6144 and Az39 in alginate matrix is a potential alternative to enhance peanut growth even under RWC. KEY POINTS: ⢠Alginate encapsulation enhances viability of SEMIA6144 or Az39 under storage at 4 °C for 1 year. ⢠Alginate beads 2% ensure the gradual release of the microorganisms. ⢠Cells from beads stored for long periods present chemotaxis and adhesion to peanut root. ⢠Peanut inoculation with 1-year-old SEMIA6144 beads improves nodulation and growth in RWC.
Assuntos
Azospirillum brasilense , Bradyrhizobium , Alginatos , Arachis , Sobrevivência CelularRESUMO
A commercial biomedical Polyimide (PI) film was topographically and chemically modified by generating micrometric periodic arrays of lines using Direct Laser Interference Patterning (DLIP) in order to improve antifouling and antibacterial properties. DLIP patterning was performed with periods from 1⯵m to 10⯵m. The physical modification of the surface was characterized by SEM, AFM and contact angle measurements and, the chemical composition of the ablated surfaces was analyzed by ATR-IR and XPS spectroscopies. The antibacterial effects were evaluated through the effect on Pseudomonas aeruginosa colonies growth on the LB (Luria Bertani) broth. The results showed that the laser treatment change the topography and as a consequence the chemistry surface, also that the microstructured surfaces with periods below 2⯵m, exhibited a significant bacterial (P. aeruginosa) adhesion decrease compared with non-structured surfaces or with surfaces with periods higher than 2 µm. The results suggest that periodic topography only confer antifouling properties and reduction of the biofilm formation when the microstructure presents periods ranging from 1⯵m to 2⯵m. On the other hand, the topography that confer strong antifouling superficial properties persists at long incubation times. In that way, polymer applications in the biosciences field can be improved by a surface topography modification using a simple, single-step laser-assisted ablation method.
Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Desenvolvimento de Medicamentos , Pseudomonas aeruginosa/efeitos dos fármacos , Resinas Sintéticas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Aderência Bacteriana/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Resinas Sintéticas/síntese química , Resinas Sintéticas/química , Propriedades de SuperfícieRESUMO
Polyaniline nanoparticles (PANI-NPs) were easily obtained applying the solvent displacement method by using N-methylpyrrolidone (NMP) as good solvent and water as poor solvent. Different polymers such as polyvinylpyrrolidone (PVP), chondroitin sulfate (ChS), polyvinyl alcohol (PVA), and polyacrylic acid (PAA) were used as stabilizers. Dynamic light scattering and scanning electron microscopy corroborated the size and morphology of the formed NPs. It was demonstrated that the size of nanoparticles could be controlled by setting the concentration of PANI in NMP, the NMP to water ratio, and the stabilizer's nature. The functionalization and fluorescence of NPs were checked by spectroscopic techniques. Since polyaniline show only weak intrinsic luminescence, fluorescent groups were linked to the polyaniline chains prior to the nanoparticle formation using a linker. Polyaniline chains were functionalized by nucleophilic addition of cysteamine trough the thiol group thereby incorporating pendant primary aliphatic amine groups to the polyaniline backbone. Then, dansyl chloride (DNS-Cl), which could act as an extrinsic chromophore, was conjugated to the amine pendant groups. Later, the functionalized polyaniline was used to produce nanoparticles by solvent displacement. The optical and functional properties of fluorescent nanoparticles (F-PANI-NPs) were determined. F-PANI-NPs in the conductive state (pH < 4) are able to absorb near infrared radiation (NIR) creating a photothermal effect in an aqueous medium. Thus, multifunctional nanoparticles are obtained. The application of NIR on a F-PANI-NPs dispersion in contact with Pseudomonas aeruginosa causes bacterial death. Therefore, the F-PANI-NPs could be tracked and applied to inhibit different diseases caused by pathogenic microorganisms and resistant to antibiotics as well as a new disinfection method to surgical materials.
Assuntos
Compostos de Anilina/síntese química , Bactérias/isolamento & purificação , Viabilidade Microbiana , Nanopartículas/química , Tamanho da Partícula , Fototerapia , Solventes/química , Compostos de Anilina/química , Difusão Dinâmica da Luz , Hidrodinâmica , Concentração de Íons de Hidrogênio , Nanopartículas/ultraestrutura , Pirrolidinonas/química , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , TemperaturaRESUMO
With the rapid growth of nanotechnology and the applications of nanoparticles, environmental exposure to these particles is increasing. However, their impact in human and environmental health is not well studied. Anurans, with life stage comprising embryos, tadpoles and adults, have an extremely permeable skin which makes them excellent indicators of environmental health. This study evaluated the acute toxicity effects of polyaniline nanoparticles (PANI-Np) in different dispersant on embryos and larvae of Rhinella arenarum. The results showed that LC50 of PANI-Np dispersed in polyvinylpyrrolidone (PVP) were 1,500 mg/L, while LC50 by PANI-Np dispersed in PVP+PNIPAM (polyN-isopropylacrilamide) showed a highest toxicity (1,170 mg/L). The embryo teratogenicity increased with increasing exposure concentration in both kinds of PANI-Np although in PANI-Np1, there is an increased teratogenic effect associated with the polymer stabilizer PVP.
Assuntos
Compostos de Anilina/toxicidade , Nanopartículas/toxicidade , Teratogênicos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bufo arenarum , Embrião não Mamífero/efeitos dos fármacos , Larva/efeitos dos fármacos , Modelos AnimaisRESUMO
The fate and effect of nanomaterials in the environment is of paramount importance towards the technological application of the materials. This work shows the ecotoxicological potential of polyaniline (PANI) nanofibers in the larvae Rhinella arenarum by means of AMPHITOX test. Acute toxicity of PANI nanofibers towards embryos of the common South American toad R. arenarum (Anura: bufonidae) was evaluated in the premetamorphosis (stage 25) larvae. The exposure of R. arenarum larvae to at dose of 150, 250 and 400 mg L(-1) resulted in 100% viability within 96 h exposure. The embryos at 2-4 blastomers stage (early life stage teratogenic test) revealed that embryos were not killed and no teratogenic effects were observed when embryos were incubated with PANI nanofibers (150 and 250 mg L(-1)), while only a growth retardation of embryos was induced at levels of 250 mg PANI nanofibers L(-1). On the other hand, at 400 mg L(-1) concentration, a reduction in the body length of larvae and tail malformation was observed. This results suggest that a concentration-dependent toxicity is operative, typified by phenotypes that had abnormal body axes. The presence of PANI nanofibers in gut contents and its excretion by larval stages of R. arenarum was confirmed by UV-visible spectroscopy.
Assuntos
Compostos de Anilina/química , Bufonidae/crescimento & desenvolvimento , Nanofibras/toxicidade , Animais , Embrião não Mamífero , Feminino , Larva/efeitos dos fármacos , Larva/metabolismo , Masculino , Nanofibras/química , Testes de ToxicidadeRESUMO
The fabrication of advanced architectures in poly(glycidylmethacrylate-co-styrene) (PGMA-S) copolymers using direct laser interference patterning (DLIP) and its selective functionalization is reported. The structure features depend mainly on the laser energy used and on the styrene content in the copolymer. The topography, measured by electronic scanning microscopy, show regular and ordered arrays for the polystyrene (PS) and for the copolymers PGMA-S. The surface PS homopolymer is ablated at the position of maximum light fluence (constructive interference), while in the copolymers the surfaces swell up at the regions with maximal fluence. The styrene units are shown to absorb the laser energy giving photothermally ablated regions or promoting the chemical decomposition of acrylate units or polymer segments. In that way, DLIP provides a unique way to produce regularly ordered structures protruding or depressing from the polymer surface without altering to a large extent the chemical nature of the material. In addition, it is shown, using fluorescence microscopy, that amine-polyethylenglycol-CdSe quantum dots (NH(2)-PEG-QDs) could be spatially localized by reaction with patterned surfaces of PGMA-S. In that way, it is proven that a patterned and chemically reactive surface can be created using DLIP of PGMA-S.
Assuntos
Nanoestruturas/química , Polímeros/química , Acrilatos/química , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Poliestirenos/química , Pontos Quânticos , Propriedades de SuperfícieRESUMO
Photodynamic therapy (PDT) is an alternative modality for cancer therapy. It induces neoplasic cells death through photoachievable sensitizers. The aim of this work was to evaluate the pharmacokinetic, toxic and phototherapeutic effects of the phthalocyanine ZnPcCF(3) in a Balb/c mice tumor model. Biodistribution studies were carried out by intraperitoneal injection of 0.2mg/kg ZnPcCF(3). Histological studies and serum biochemical parameters were used to evaluate hepatic and renal toxicity and functionality. After tumor irradiation (210J/cm(2)), an analysis of tumor necrosis degree was used to evaluate the phototherapeutic effects. It was measured at 1, 2, 3 and 4 days after PDT. Vital staining was performed by intraperitoneal injection of 0.35ml 1% Evans Blue solution. Six hours later, tumors were excised and examined. The unstained area was attributed to necrotic tissue, whereas the stained area showed tissue with preserved blood supply. ZnPcCF(3) was accumulated in spleen, liver and duodenum. It suggests that ZnPcCF(3) is eliminated from the body via bile-gut. The phthalocyanine was not found in brain, therefore, it would not cross the blood-brain barrier, thus toxicity risk in the central nervous system is not probable. Moreover, ZnPcCF(3) does not accumulate in skin, it would eliminate cutaneous photosensitizing risks. The dose of 0.2mg/kg ZnPcCF(3) resulted in a low acute toxicity with revertible damages, which indicates that this dose can be used for PDT. The tumor death was of 89% 4 days after PDT. It indicates that ZnPcCF(3) would be effective in PDT.
Assuntos
Indóis/farmacologia , Neoplasias Mamárias Experimentais/tratamento farmacológico , Compostos Organometálicos/farmacologia , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Animais , Azul Evans/administração & dosagem , Feminino , Indóis/farmacocinética , Indóis/toxicidade , Injeções Intraperitoneais , Isoindóis , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Necrose , Compostos Organometálicos/farmacocinética , Compostos Organometálicos/toxicidade , Fármacos Fotossensibilizantes/farmacocinética , Fármacos Fotossensibilizantes/toxicidade , Coloração e Rotulagem/métodos , Fatores de Tempo , Distribuição Tecidual , Testes de Toxicidade , Compostos de ZincoRESUMO
Photodynamic therapy (PDT) is an innovative treatment for several types of malignant and non-malignant disease. In the present study, ZnPcOCH(3) was investigated on a human larynx-carcinoma cell line (Hep-2) for its use in PDT. This drug exhibited favourable properties as a photosensitizer in vitro because ZnPcOCH(3) is able to penetrate efficiently in the cytoplasm of cultured cancer cells and is partially localized in lysosomes. The results show that ZnPcOCH(3)-PDT-induced apoptosis by caspase dependent pathway. The new compound shows a good photosensitizing efficiency in vitro on Hep-2 cells, encouraging further in vivo studies.