Mutual influence of selenium nanoparticles and FGF2-STAB® on biocompatible properties of collagen/chitosan 3D scaffolds : in vitro and ex ovo evaluation

In a biological system, nanoparticles (NPs) may interact with biomolecules. Specifically, the adsorption of proteins on the nanoparticle surface may influence both the nanoparticles' and proteins' overall bio-reactivity. Nevertheless, our knowledge of the biocompatibility and risk of exposure to nanomaterials is limited. Here, in vitro and ex ovo biocompatibility of naturally based crosslinked freeze-dried 3D porous collagen/chitosan scaffolds, modified with thermostable fibroblast growth factor 2 (FGF2-STAB®), to enhance healing and selenium nanoparticles (SeNPs) to provide antibacterial activity, were evaluated. Biocompatibility and cytotoxicity were tested in vitro using normal human dermal fibroblasts (NHDF) with scaffolds and SeNPs and FGF2-STAB® solutions. Metabolic activity assays indicated an antagonistic effect of SeNPs and FGF2-STAB® at high concentrations of SeNPs. The half-maximal inhibitory concentration (IC50) of SeNPs for NHDF was 18.9 µg/ml and IC80 was 5.6 µg/ml. The angiogenic properties of the scaffolds were monitored ex ovo using a chick chorioallantoic membrane (CAM) assay and the cytotoxicity of SeNPs over IC80 value was confirmed. Furthermore, the positive effect of FGF2-STAB® at very low concentrations (0.01 µg/ml) on NHDF metabolic activity was observed. Based on detailed in vitro testing, the optimal concentrations of additives in the scaffolds were determined, specifically 1 µg/ml of FGF2-STAB® and 1 µg/ml of SeNPs. The scaffolds were further subjected to antimicrobial tests, where an increase in selenium concentration in the collagen/chitosan scaffolds increased the antibacterial activity. This work highlights the antimicrobial ability and biocompatibility of newly developed crosslinked collagen/chitosan scaffolds involving FGF2-STAB® and SeNPs. Moreover, we suggest that these sponges could be used as scaffolds for growing cells in systems with low mechanical loading in tissue engineering, especially in dermis replacement, where neovascularization is a crucial parameter for successful skin regeneration. Due to their antimicrobial properties, these scaffolds are also highly promising for tissue replacement requiring the prevention of infection

Thermogelling water solutions of multifunctional macromonomers based on PLGA-PEG-PLGA triblock copolymers

Biodegradable thermosensitive triblock copolymers based on poly(ethylene glycol) and poly[(lactic acid)-co-(glycolic acid)](PLGA-PEG-PLGA) with PLGA/PEG weight ratio in the range of 1.5–3.0 and LA/GA molar ratio equal to 2.4 or 3.0 were prepared via ring opening polymerization (ROP). Prepared copolymers were subsequently modified in “one pot” by itaconic anhydride (ITA) in order to functionalize both ends with carboxylic acid groups and reactive double bonds. Chemical structure was characterized by means of gel permeation chromatography and nuclear magnetic resonance. Aqueous solutions of both modified and unmodified copolymers are able to form free flowing sol at room temperature and clear gel at temperature around 37°C. Therefore, sol-gel transitions of PLGA-PEG-PLGA and ITA/PLGA-PEG-PLGA/ITA copolymers in aqueous solutions were investigated using test tube inverting method. No mater if copolymer is modified or not, it was found that the critical gel temperature (CGT) increased when the PLGA/PEG weight ratio dropped from 2.5 to 2.0 and that the critical gel concentration (CGC) grew up with decreasing molar ratio of LA/GA from 3.0 up to 2.4. However, in all cases the ITA functionalization improved sol-gel characteristics of original PLGA-PEG-PLGA copolymer by approaching gel phase to body temperature. As a result, aqueous solution of ITA/PLGA-PEG-PLGA/ITA having LA/GA = 3 and PLGA/PEG = 2 with concentration higher than 6 wt% might be suitable material for biomedical applications as injectable temporary implants

Nutrição mineral, crescimento e teor de óleo essencial da menta em solução nutritiva sob diferentes concentrações de fósforo e épocas de coleta Mineral nutrition, growth and essential oil content of mint in nutrient solution under different phosphorus concentrations

Avaliou-se o efeito de concentrações de P e épocas de coleta sobre o crescimento, nutrição mineral e teor de óleo essencial da menta (Mentha piperita L.). O delineamento experimental foi em blocos casualizados com parcelas subdivididas, em esquema fatorial 2x5, sendo 2 épocas de coleta (65 e 95 dias de cultivo (DC)) e 5 concentrações de P na solução nutritiva (6; 12; 18; 24 e 30 mg L-1), com 4 repetições. Foi determinada a massa seca de folhas (MSF), caules (MSC), raízes (MSR) e total (MST) e as relações folha:caule (F:C) e parte aérea:raiz (PA:R). Também, foi determinado o teor de óleo essencial em folhas frescas. Os níveis críticos foliares e acúmulo de nutrientes na parte aérea da menta foram estimados por meio da análise química das folhas e caules. As concentrações de P na solução influenciaram o crescimento e a produção de óleo essencial pela menta. Na coleta realizada aos 65 DC, apenas a MSF foi influenciada pelo P, não se observando efeito sobre os teores de óleo essencial. Aos 95 DC, o aumento da concentração de P promoveu aumentos significativos na massa seca das partes e do total da menta e, também, nos teores de óleo essencial, sendo o teor máximo (2,192 dag kg-1) obtido com 19,50 mg L-1 de P. As maiores concentrações de P avaliadas (24 e 30 mg L-1), promoveram aumentos na produção de matéria fresca e seca da parte aérea da menta, mas, reduziram os teores de óleo essencial, devido ao efeito de diluição, não significando, portanto, ganhos de produção de óleo por planta. Os teores foliares dos nutrientes associados ao teor máximo de óleo aos 95 DC foram em g kg-1: N=37,2; =3,9; K=21,2; Ca=9,3; Mg=3,8; S=3,0; e, em mg kg-1: B=35; Cu=8; Fe=323; Mn=145 e Zn=22. A exigência nutricional aos 95 DC relacionada ao teor máximo de óleo essencial seguiu a seqüência: N>K>Ca>P>Mg>S>Fe>Mn>B>Zn>Cu.<br>The effect of P concentrations and harvest period upon the growth, mineral nutrition and essential oil content of mint (Mentha piperita L.) was evaluated. The experimental design was of randomized blocks in a split-plot scheme, in a 2x5 factorial with four replications, being two harvest periods (65 and 95 days of cultivation (DC)) and five concentrations of P in the nutrient solution (6; 12; 18; 24 and 30 mg L-1) evaluated. The leaves dry weight (MSF), stems dry weight (MRS), roots dry weight (MSR), total dry weight (MST), leaf:stem ratio (F:C) and aerial part:root ratio (PA:R) were evaluated. The essential oil content in fresh leaves was determined. The critical levels and nutrient accumulation in leaves and stems were estimated through leaves and stems chemical analysis. The level of P increased the leaf dry matter production 65 DC. At 95 DC, the P concentration in the nutrient solution, did significantly increase plant growth and essential oil content, the maximum essential oil content being (2.192 dag kg-1) obtained with 19.48 mg L-1 of P. The higher P concentration in nutrient solution (24 and 30 mg L-1), increased the fresh and dry matter of the aerial portion of the plants, but, decreased the essential oil content. Due to the dilution effect, the increase of fresh and dry matter production did not result in an increase in the oil yield per plant. The critical levels of nutrients in the leaves corresponding to the maximum essential oil content at 95 DC in g kg-1 were: N=37,2; P=3,9; K=21,2; Ca=9,3; Mg=3,8; S=3,0 and, in mg kg-1: B=35; Cu=8; Fe=323; Mn=145 and Zn=22. The nutrients requested at 95 DC related to the maximum essential oil content was: N>K>Ca>P>Mg>S>Fe>Mn>B>Zn>Cu

Desenvolvimento de mudas de bromélia (Neoregelia cruenta (R. Graham) L. B. Smith) cultivadas em diferentes substartos e adubação foliar Development of plantlets of bromeliad (Neoregelia cruenta) cultivated in different substrates and leaf fertilizers

As bromélias apresentam formas exóticas com uma grande diversidade de cores e de flores, constituindo importantes espécies para uso em paisagismo e floricultura. Em conseqüência disto, são muito comercializadas. Porém, parte das plantas que se encontram no mercado, ainda são provenientes do extrativismo. Esta situação é também reflexo do pequeno número de informações sobre técnicas de propagação e cultivo. Uma das limitações é o desconhecimento do tipo de substrato e adubação adequados ao cultivo destas espécies. Assim, o objetivo deste trabalho foi avaliar o crescimento de bromélias do Neoregelia cruenta, cultivadas em diferentes substratos e adubações foliares através da altura, do número de folhas, da matéria fresca e seca, da parte aérea e das raízes. As mudas utilizadas foram provenientes de cultura de tecidos. Após um período de pré-aclimatização, foram transplantadas para estufa sem nebulização. Os substratos foram constituídos da mistura de diferentes proporções de solo, areia, casca de arroz carbonizada e por um substrato comercial à base de vermiculita. Aos substratos foi aplicada adubação foliar, combinando uréia e sacarose, em intervalos de quinze dias. Os resultados obtidos mostraram que as interações entre os substratos, dose de sacarose e de uréia, não afetaram a altura das mudas e o número de folhas. O uso de sacarose também não influenciou o desenvolvimento das mudas. O substrato comercial à base de vermiculita, independente da aplicação de adubação foliar, proporcionou maior altura das mudas e número de folhas. A aplicação de uréia apresentou efeito linear crescente durante o período avaliado.<br>The bromeliads present exotic forms with a great variety of colors and flowers and are considered as important species used in landscape design and floriculture. As a consequence, these species are well commercialized. However, a part of these plants still come from natural extraction. This situation is also a consequence of the reduced technical information regarding its propagation and development. One of the limitations is the lack of knowledge regarding the type of substrate and adequate fertilizer for its cultivation. The objective of this study was to evaluate the development of Neoregelia cultivated in different substrates and leaf fertilizers through the variables height, leaf number and fresh and dry matter of shoots and roots. The plantlets used were produced by tissue culture. After a period of pre-acclimatization, the plantlets were transferred to a green house without nebulization. The substrates consisted of different proportions of soil, sand and carbonized rice husk and a commercial substrate composed of vermiculite. Leaf fertilizers were applied to the substrates combining urea and sucrose in intervals of fifteen days. The results showed that the interactions of the substrates and the sucrose and urea dosages had no effect on height and leaf number. The use of sucrose also showed no influence on plant development. The commercial substrate composed of vermiculite, independent of the leaf fertilizer application, showed the best results for plant height and leaf number. The use of urea presented a crescent linear effect during the evaluated period