Isabel Nogueira

Development of multicore hybrid particles for drug delivery through the precipitation of CO2 saturated emulsions.

Hybrid lipid-polymer particles are gaining increasing interest to be applied as drug delivery systems due to their greater stability in biological fluids and enhanced cellular uptake of drugs. However, a major drawback is the fact that these particles are usually produced through techniques that use organic solvents. This work studies the possibility of producing for the first time hybrid particles composed by lipid multicores enveloped in a polymeric layer through Particles from Gas Saturated Solutions (PGSS(®)), without using organic solvents. An oil-in-water emulsion, composed by Gelucire 43/01™ (GEL) as the discontinuous phase and by an aqueous polyethylene glycol 4000 (PEG) solution as the continuous phase, was successfully precipitated by PGSS(®). Operating conditions that ensured the stability of the CO2 saturated emulsion were previously evaluated. The resulting PEG-GEL particles present a spherical-like morphology constituted by several lipid cores encapsulated into a polymeric shell. The applicability of these structured particles to be used as drug delivery system (DDS) was studied by using ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID), as model drug. The particles provided an initial burst release of the drug due to the progressive dissolution of the external layer of PEG, followed by a controlled release of the NSAID from the GEL cores.

Spectroscopic Characterization of a Contemporary Indian Miniature Painting

A case study on a contemporary Indian miniature was carried out through the application of different spectroscopic techniques. Painting support, pigments, and dyes were largely characterized by means of energy dispersive x-ray fluorescence and Raman microspectroscopy directly on the artwork. Regarding golden motifs and silvered areas, for which these techniques have not provided enough information, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was used as a complementary technique. The painting support was identified as the Bombyx mori silk. Among the colorant matters, several pigments were identified such as chrome yellow, lithopone, hematite, lamp black, mica-titania pearlescent pigment, and tin-based metallic silver, and dyes such as phthalocyanine blue and the recent synthetic pigment red PR9 naphthol AS. All this materials will provide evidence in the support of the contemporary production of the artwork for future studies.

Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity.

Microscopy and X-Ray Spectroscopy Analyses for Assessment of Gilding and Silvering Techniques of Portuguese Illuminated Manuscripts

The objects of this study are various local charters (cartas de foral, in Portuguese) granted by Dom Manuel I, King of Portugal (1495-1521), which substituted for medieval ones and were intended to achieve an administrative unification. These are luxuriously illuminated manuscripts, and our study aims at obtaining a better understanding of the gilding and silvering techniques applied to the parchments, in which the forais were written, between 1500 and 1520. The combined use of microscopy and X-ray spectroscopy analyses allowed us to identify the vestigial materials used for making the parchments, including products such as salt (NaCl), lime (CaO), pumice stone (SiO2+Al2O3), and chalk (CaCO3). Chalk was employed as a whitening agent to give the parchment its final color and opacity. Shell-gold and shell-silver mixed in with animal glue or gum binding media were directly applied on type 1 and 3 forais, while very thin gold leaves (<1 µm) were applied over lead-based tempera grounds (50-180 µm thick) in type 2 forais. Silver was always employed in its finest form without a further protective layer (thus its recursive state of corrosion), while gold was used in various alloy grades.

A way to prepare a liposoluble natural pink colourant

Cactus pears (Opuntia spp.) have been identified as a promising betalainic crop covering a wide colour spectrum from yellow to purple pigments. The aim of this study was to exploit the use of supercritical fluid technology to develop lipidic particles of betalain-rich extract derived from Opuntia spp. fruits to be further incorporated in food matrices. A natural extract was encapsulated by the PGSS® (Particles from Gas Saturated Solutions) technique into glyceryl monoostearate, using a surfactant (polyglyceryl-3 polyricinoleate) and water. Different process conditions, namely pressure (9–23 MPa), temperature (57–73 °C) and equilibrium time (5–55 min), were tested in order to model the encapsulation of betalains via the Response Surface Methodology (RSM), following a Central Composite Rotatable Design (CCRD). Results showed that temperature and pressure were the parameters that mostly affected the encapsulation of the natural pigment and the highest betacyanin encapsulation was achieved at lower pressures. This effect was more pronounced at higher temperatures and lower equilibrium times. Under these conditions, Opuntia spp. particles presented 64.4 mg per 100 g of betacyanins and high antioxidant capacity. In addition, the particles with higher betacyanin content showed an average particle size of 10 μm and a melting point between 57 and 65 °C. When compared with the Opuntia dried extract, lipidic particles contributed to a better homogenization of the pink colour after incorporation in ice cream.

Formulation of pea protein for increased satiety and improved foaming properties

Pea protein has been associated with promoting the satiety effect. One of the issues associated with the incorporation of pea protein in food products is the product homogeneity due to its solubility and dispersibility issues. Within this context, one goal of this study was to exploit the use of supercritical fluid technology to develop Solid Lipid Pea Particle (SLPP) aiming at improving dispersibility in fat-based products. PP was encapsulated by the PGSS® (Particles from Gas Saturated Solutions) technique into glyceryl dipalmitostearate (E471) and olive oil. Different process conditions, namely pressure (7.3–20.7 MPa), temperature (51–75 °C) and equilibrium time (3–37 min) were tested in order to optimize the encapsulation of pea protein via Response Surface Methodology (RSM), following a Central Composite Rotatable Design (CCRD). Results showed that pressure and the interaction between pressure and temperature had a significant impact (p < 0.05) on the protein load and thus on the encapsulation efficiency. The highest encapsulation efficiency (96%) was achieved at 14 MPa, 51 °C and 20 min. Under these conditions, SLPP presented 0.15 mg of protein per mg of particles and 84% of lipase inhibitory activity. When compared with the PP (non-encapsulated), liposoluble pea protein particles contributed to a better product homogenization. The food industry can also take advantage of the ability of pea protein for foam stabilization in aqueous food products. Therefore, PP was treated with high-pressure supercritical CO2 treatment (HPT-scCO2) that has led to improved foaming properties when compared with the non-treated PP.

Pathogens in ornamental waters: a pilot study

In parks, ornamental waters of easy access and populated with animals are quite attractive to children and yet might hide threats to human health. The present work focuses on the microbiota of the ornamental waters of a Lisboa park, characterized during 2015. The results show a dynamic microbiota integrating human pathogens such as Klebsiella pneumoniae, Aeromonas spp. and Enterobacter spp., and also antibiotic resistant bacteria. K. pneumoniae and Aeromonas spp. were present as planktonic and biofilm organized bacteria. In vitro K. pneumoniae and Aeromonas spp. showed an enhanced ability to assemble biofilm at 25 °C than at 37 °C. Bacteria recovered from biofilm samples showed an increased antibiotic resistance compared to the respective planktonic counterparts.

Risk assessment for public health from human interaction with ornamental waters

Absctract publicado em: Microsc Microanal. 2016 Mar;22(Suppl S4):12-13. doi: 10.1017/S1431927616000258. Disponivel em: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10231261&fulltextType=AB&fileId=S1431927616000258

The 1685 blue smalt coating of the Coimbra Old Cathedral main altarpiece under scrutiny

Although smalt was used as an important pigment in European oil painting during the 16th and 17th century, records of its use in a monumental tridimensional artwork and even more in a tempera coating remain quite scarce. The main altarpiece of the Coimbra Old Cathedral is an interesting case study to shed light on the use of smalt and the trade practices of painters at the baroque period, in Portugal. The primitive colour scheme of this artwork of a Flamboyant style, achieved in 1502, was renovated during three subsequent interventions [1]. According to a historical record [2], a new polychromy was to be undertaken in 1685 by the local painter Manoel da Costa Pereira. Smalt pigment bound in oil was to be applied to the original blue surfaces, then ‘burnished’ to produce a polished smalt coating. A later restoration carried out in 1900 actually prevents from seeing what lies underneath. Several micro-samples were collected in the blue background and niches of the altarpiece. They were examined by optical microscopy (MO), Scanning electron microscopy (SEM) with energy dispersive X-ray Spectroscopy (EDS) and a staining protocol, to verify if the aforesaid pigment has effectively been used and if a drying oil has been employed as binder and a mean to obtain a high reflective blue surface. All the samples cross-sections observed by OM unveiled the 1685 blue coating, always containing several grades of smalt mixed together given their more or less intense hue for grains of similar size (Figs.1-2). SEM imaging put in evidence the conchoidal fractures of the particles, specific to the blue cobalt-containing potash glass and its processing by pouring the glass paste into cold water where it disintegrated into particles for its further use as a pigment [3]. SEM-EDS analyses performed on individual grains allowed the systematic detection of Si, K, Co, Fe and As, and sometimes traces of Ca and Al, except for St. Luke’s niche where Co was hardly found. The Co contents (about 3-4 wt%) are the expected ones, irrespective of the blue particles intensity [4-5], but its average of 1 w% in St. Luke’s niche may be related to a deliberate choice by the artist to apply there a paler pigment. Ni was sometimes detected within the grains. Its presence may point the use of smaltite, [Co, Ni]As3-2, member of the cobalt iron nickel arsenide minerals sourced from Saxonia, or erytrite ([Co,Ni]3[AsO4]2.8(H2O)), but its absence may also point the use of cobaltite, (Co, Fe)AsS, sourced from Sweden [3,6], therefore indicating the use of marketed products of at least two origins. The very low As content, varying between 2.2 wt% (Virgin background) and 0.9 wt% (St. Luke and Paul’s niches) suggests the cobalt ore was calcined so as to eliminate volatile compounds such as arsenic. Although the transparent particles of smalt were coarsely ground (the largest one measuring the impressive 64 μm across) to overcome their low hiding power, an unexpected result came out by OM and SEM-EDS giving evidence of the use of lead-based light blue and pink underlayers (Figs. 1-2) to give the final blue smalt coating more intense and subtle shades. Micro-chemical analyses carried out on cross-sections with a staining protocol (acid fuchsin and rhodamine B dyes) showed confusing results regarding the binder. It seems that smalt was bound with a proteinaceous substance stained red by acid fuchsin, such as parchment or animal glue, likely to prevent the pigment from being altered by the yellowing of a drying oil. The gelatinous nature of the binding medium kept the particles clearly suspended until the paint became dry. A final oil film might have been soon applied 158 doi:10.1017/S1431927614014494 Microsc. Microanal. 21 (Suppl 6), 2015

Microencapsulation of α-tocopherol with zein and β-cyclodextrin using spray drying for colour stability and shelf-life improvement of fruit beverages

α-Tocopherol (TOC) has become an important food additive due to its antioxidant effect and capacity to increase shelf-life of products. However, it is a hydrophobically active compound, which compromises its applicability in soft drinks and fruit beverages. The aim of this study was to develop sustained release forms of α-tocopherol using zein and cyclodextrin as carriers to be further applied in fruit beverage products for improved shelf-life. For this purpose, the encapsulation of α-tocopherol into zein protein was first optimized using a spray-drying technology. Different process conditions, namely temperature (110–180 °C) and solids concentration (0.01–0.04 g mL−1), were tested aiming at maximizing the encapsulation of α-tocopherol and antioxidant capacity using response surface methodology (RSM) following a Face Centred Design (FCD). Results showed that lower inlet gas temperature and lower solids concentration enable the production of α-tocopherol:zein forms with a higher antioxidant activity (oxygen radical absorbance capacity >90 μmol Trolox equivalent antioxidant capacity per g), and the highest encapsulation efficiency (42.05%) was obtained using 0.02 g mL−1 of solids concentration. β-Cyclodextrin was further added to the best system to increase the solubility capacity of α-tocopherol in fruit juice beverages. Despite the lower antioxidant activity (46.2 μmol Trolox equivalent antioxidant capacity per g), α-tocopherol:zein:cyclodextrin forms reduced colour losses when compared to the normal juice, and this effect was probably related to the suppression of anthocyanin degradation due to the formation of inclusion complexes with β-cyclodextrin. Importantly, none of these forms induced cytotoxicity in the Caco2 cell model, confirming the safety of these systems.