Cristina M. R. Rocha

Interactions of Microbicide Nanoparticles with a Simulated Vaginal Fluid

The interaction with cervicovaginal mucus presents the potential to impact the performance of drug nanocarriers. These systems must migrate through this biological fluid in order to deliver their drug payload to the underlying mucosal surface. We studied the ability of dapivirine-loaded polycaprolactone (PCL)-based nanoparticles (NPs) to interact with a simulated vaginal fluid (SVF) incorporating mucin. Different surface modifiers were used to produce NPs with either negative (poloxamer 338 NF and sodium lauryl sulfate) or positive (cetyltrimethylammonium bromide) surface charge. Studies were performed using the mucin particle method, rheological measurements, and real-time multiple particle tracking. Results showed that SVF presented rheological properties similar to those of human cervicovaginal mucus. Analysis of NP transport indicated mild interactions with mucin and low adhesive potential. In general, negatively charged NPs underwent subdiffusive transport in SVF, i.e., hindered as compared to their diffusion in water, but faster than for positively charged NPs. These differences were increased when the pH of SVF was changed from 4.2 to 7.0. Diffusivity was 50- and 172-fold lower in SVF at pH 4.2 than in water for negatively charged and positively charged NPs, respectively. At pH 7.0, this decrease was around 20- and 385-fold, respectively. The estimated times required to cross a layer of SVF were equal to or lower than 1.7 h for negatively charged NPs, while for positively charged NPs these values were equal to or higher than 7 h. Overall, our results suggest that negatively charged PCL NPs may be suitable to be used as carriers in order to deliver dapivirine and potentially other antiretroviral drugs to the cervicovaginal mucosal lining. Also, they further reinforce the importance in characterizing the interactions of nanosystems with mucus fluids or surrogates when considering mucosal drug delivery.

Enzymatic Hydrolysis of Whey Protein Concentrates: Peptide HPLC Profiles

Abstract Hydrolysis of whey protein concentrates (WPCs) at different temperatures and pHs, using three enzymes: pepsin, trypsin, and Alcalase®, was monitored during more than 5 hr by reversed phase HPLC/UV, using a column containing a polystyrene‐divinylbenzene copolymer‐based packing, and an elution gradient from 8% to 80% acetonitrile containing 0.1% TFA. Peptides were separated according to their polarity and size, and degradation of α‐lactalbumin (α‐la) and β‐lactoglobulin (β‐lg) was evaluated. The three proteolytic enzymes (pepsin, trypsin, and Alcalase®) employed for hydrolysis of WPCs led to different kinetics of degradation of β‐lg. α‐la degradation after 15 min was almost complete for the three enzymes. The hydrolysis catalysed by each enzyme resulted in different peptide profiles by HPLC/UV. Hydrolysates produced by pepsin (HP) were resolved into three main fractions of high retention times, while tripsin hydrolysates (HT) were resolved into nine major peaks and Alcalase® hydrolysates (HA) were resolved into 12 major peaks, presenting a wide range of polarities and sizes. Although, with different β‐lg hydrolysis extension, chromatographic profiles of the degradation and formation of peptides can be used as a finger print of the type of enzyme used, because peptide profile is not affected either by temperature or pH.

Electric field-based technologies for valorization of bioresources

This review provides an overview of recent research on electrotechnologies applied to the valorization of bioresources. Following a comprehensive summary of the current status of the application of well-known electric-based processing technologies, such as pulsed electric fields (PEF) and high voltage electrical discharges (HVED), the application of moderate electric fields (MEF) as an extraction or valorization technology will be considered in detail. MEF, known by its improved energy efficiency and claimed electroporation effects (allowing enhanced extraction yields), may also originate high heating rates - ohmic heating (OH) effect - allowing thermal stabilization of waste stream for other added-value applications. MEF is a simple technology that mostly makes use of green solvents (mainly water) and that can be used on functionalization of compounds of biological origin broadening their application range. The substantial increase of MEF-based plants installed in industries worldwide suggests its straightforward application for waste recovery.

Protein-based resins for food packaging

Abstract: Currently, mainly non-biodegradable petroleum-based synthetic polymers are used as packaging materials for foods, because of their availability, low cost and functionality. However, biodegradable/edible films can be made from polysaccharides, proteins and lipids without the environmental issues of petroleum-based polymers and with the additional advantage of being available from renewable sources or as by-products or waste-products from the food and agriculture industries. Although these sources are not enough, by far, to replace the synthetic polymers/films, they can help in reducing packaging wastes and can replace them in specific applications. Proteins have the extra advantage of allowing a wider range of functional properties than polysaccharides and lipids. This is conferred by their composition based on combinations of 20 different amino acids, which usually allows high intermolecular binding. This chapter starts by describing the main protein sources used in packaging materials, followed by a section dealing with materials processing and characterization. The chapter ends with an overview of current and foreseen applications. Nanotechnology applications through the utilization of materials at the nano-scale size in protein-based films are a valuable alternative for the improvement of the properties of packaging materials (water vapour transmission, mechanical, thermal). In particular, nanofilms and multi-nanolayer films constitute promising solutions for food applications using protein-based materials.

Study of the rheological behaviour of human blood using a controlled stress rheometer

The aim of this work was to investigate the rheological behaviour of human blood, in a controlled stress rheometer, using different cone-plate and parallel plate geometries. Steady-shear (flow curves and kinetics) and oscillatory (strain, frequency and time sweeps) tests were performed at 37°C. The results demonstrated that rheological data are significantly influenced by the measuring geometry and the rheological parameters obtained from rheological models must be analysed with great caution. The Cross model provided a better fit of the flow curves and the Power Law model gave a better concordance between the rheological parameters obtained with the different measuring systems. The oscillatory measurements demonstrated a linear viscoelastic behaviour below a critical frequency and the Friedrich-Braun model described well the frequency sweeps experimental data in that region. The correlation between steady-shear and oscillatory properties (Cox-Merz rule) suggests that the two methods can be complementary and may give important information on red blood cells aggregation and deformability. Results from oscillatory time sweeps confirm a blood aggregation process in two steps.

TUMEFAÇÃO CRANIANA DE NOVO – UM DESAFIO DIAGÓSTICO

Introducao: A colecao liquida subaponevrotica e uma tume- facao craniana, benigna, que surge semanas apos o nascimen- to, decorrente provavelmente de um parto traumatico. O diag- nostico e desafiante uma vez que ha poucos casos descritos na literatura. O tratamento recomendado e conservador, ja que na maioria dos casos ha resolucao espontânea. Caso Clinico: Descreve-se um caso de uma lactente de 2 meses com antecedentes de parto distocico por ventosa e de um cefalohematoma occipitoparietal direito com reabsorcao es- pontânea no periodo neonatal. Observou-se, de novo e com 6 dias de evolucao, uma tumefacao occipitoparietal direita com 5-6 cm de maior diâmetro, de volume oscilante, consistencia mole, movel nos planos superficiais, transluzente, indolor e sem si- nais inflamatorios, permanecendo a crianca clinicamente bem. O estudo analitico, radiografia do crânio e ecografia transfon- tanelar nao tinham alteracoes de relevo. A ecografia de partes moles mostrou uma colecao liquida, sugerindo a possibilidade de um cefalohematoma. Foi feita puncao aspirativa com saida de liquido sero-hematico, sem qualquer crescimento bacteriano. Ponderando-se a possibilidade de uma malformacao congenita foi realizado RMN CE que evidenciou uma colecao liquida subga- leal. Apos revisao da literatura, o diagnostico de colecao liquida subaponevrotica revelou-se o mais provavel e o tratamento tem sido conservador. Comentarios: Apesar do impacto da sua apresentacao cli- nica, trata-se de uma entidade benigna, pouco descrita na lite- ratura, sendo por isso fundamental que os prestadores de cui- dados de saude estejam aptos para um diagnostico imediato e um acompanhamento adequado, que passa por medidas de vigilância ate a completa resolucao ao fim de algumas semanas.

Preparation and characterization of biodegradable films from keratinous wastes of the leather industry

With increasing demand for sustainable materials, keratin wastes have been regarded, in recent years, as renewable resources worthy of exploitation. Each year, the Portuguese leather industry discards a considerable amount of animal hair, which constitutes a troublesome waste product. In this study, in an attempt to find a potential utilization for this waste, the preparation of biodegradable films from bovine hair, by thermo-compression, was tested. Bovine hair formulations with 20, 30 and 40 wt % of plasticizer (glycerol, lactic acid) were pressed into films, at 147 kN and 120oC or 160oC for 4 minutes. The mechanical properties, colour, solubility and water sorption isotherms of the obtained films were assayed. All films were opaque and dark. Solubility was higher for films processed at higher temperature and with lactic acid as plasticizer. The Guggenheim-Anderson-de Boer (GAB) model gave a good fit to the experimental results for the moisture sorption isotherms. The stress at break, , and the Young’s modulus, E, decreased and the strain at break, , increased with the addition of increasing amounts of plasticizer.