Supercritical fluid technology for agrifood materials processing

This work was financially supported by Fundação para a Ciência e Tecnologia (FCT), Portugal, through the project Strategic Project UIDB/00102/2020 and Programmatic Project UIDP/00102/2020 of the Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), and UI/05704/2020 of ciTechCare. M. C. Gaspar acknowledges FCT for the financial support through the Scientific Employment Stimulus – Individual and Institutional Calls (CEECIND/00527/2017 and CEECINST/00060/2021). The authors participate in the CYTED network RESALVALOR — Valorización de Residuos de la Industria Agroalimentaria. The authors are also grateful for the work of the designer José Gomes in the preparation of Figures 1 and 2.Supercritical fluid technology has been applied in the food area for processing and preserving food products and/or monitoring the food quality, with known advantages. The main solvent used at supercritical conditions for food applications is carbon dioxide. Some examples are presented, from the traditional decaffeination of coffee up to the micronization of vanilla, passing through innovative processes such as the extrusion of protein-based snacks and drying of beetroot. The gap between research and industries is addressed, mainly due to a lack of data about food chemical changes that may occur during some processes, as well as technical data. However, this is an area in clear expansion and probably, in the future, we will have a menu composed of meals prepared by supercritical methods.info:eu-repo/semantics/publishedVersio

Comparative studies of ultrasound and membrane emulsification for the production of stable Perfluorocarbon-in-water nanoemulsions

Low-molecular weight perfluorocarbons (PFCs) are usually chemically and biologically inert, clear, colorless liquids, presenting a high affinity for many gases, namely for O2, NO and CO2, which turn them particularly suitable in various biomedical applications involving gas capture, transport and release. In fact, PFC-in-Water emulsions were one of the two major classes of systems proposed as blood substitutes and for O2/NO therapeutics. However there are still some important issues concerning this type of systems which have limited their efficiency, approval and commercial success, namely those related to emulsion stability, hydrodynamic size distribution and reduced shelf-lives. Stability issues can easily lead to PFC diffusion in water, to aggregation and to the consequent hydrodynamic size increase and emulsion degradation [1]. Nanoemulsions (typically within a range of hydrodynamic sizes of 10-100 nm) exhibit various advantages over typical microemulsions [2]. Hence, our aim is to produce monodisperse PFC nanoemulsions presenting larger surface-to-volume ratios, enhanced stabilities and more efficient gas capture/delivery properties. A first approach to achieve these goals is to prepare and to study a mixed surfactant system based on Tween 80 and on a perfluorinated surfactant (perfluorooctyl phosphocholine) at different relative compositions. PFC-in-Water nanoemulsions were produced by using the traditional ultrasound emulsification method (500W). The effects of co-surfactants relative compositions on CMC values, on the kinetics of emulsion formation and on the corresponding stabilities of prepared nanoemulsions were evaluated. Hydrodynamic sizes and Zeta-potentials were also assessed, being able to obtain stable nanoemulsions with hydrodynamic sizes between 150 and 200 nm. In a comparative study, PFC-in-Water nanoemulsions were also produced by membrane emulsification. This low energy-intensive technique has received increasing interest as it allows more flexible operating conditions. Regenerated cellulose membranes such as Nadir UC500 and Millipore Ultracel RC100, polyethersulphone membranes such as Nadir UP150 and Millipore PBHK04310, and a promising polycarbonate Whatman Track-ethched 30 nm Nuclepore membrane, were employed to produce nanoemulsions, and using the same mixed surfactant system and relative compositions. The energy inputs of these two methods were compared and discussed along with their efficiencies in terms of producing nanoemulsions presenting improved stabilities, smaller hydrodynamic sizes and narrower hydrodynamic size distributions. References [1] M.P. Krafft, A. Chittofrati, J.G. Riess, Curr Opin in Colloid Interface Sci., 8 (2003) 251–258 [2] E. Piacentini, E. Drioli, L. Giorno, J. of Membr. Sci., 468 (2014) 410–42

Biomateriais aplicados ao desenvolvimento de sistemas terapêuticos avançados

Esta obra apresenta contribuições que cobrem o estado-da-arte de vários tópicoscientíficos e técnicos e que foram desenvolvidos no âmbito das actividades científicase de formação de um projecto-em-rede CYTED, intitulado RIMADEL - Rede Ibero-Americana de Nuevos Materiales para el Diseño de Sistemas Avanzados de Liberación deFármacos en Enfermidades de Alto Impacto Socioeconómico.Este projecto pretendeu criar uma plataforma Ibero-Americana de intercâmbio deinvestigadores, de conhecimento e de recursos científicos e tecnológicos, orientadapara o desenvolvimento de novos biomateriais com aplicações em sistemas avançadosde libertação de agentes terapêuticos, e em suportes para dispositivos biomédicos eengenharia de tecidos/medicina regenerativa.Apresentam-se perspectivas abrangentes, embora muito actuais, e para que este livropossa servir também como uma obra de referência para estudantes de graduação e depós-graduação de países falantes da Língua Portuguesa ou Castelhana, em áreas comoa Engenharia (Engenharia Química, Engenharia de Materiais, Engenharia Biomédica,Engenharia Biológica), Ciências Farmacêuticas, Química, Química Medicinal, QuímicaBiológica, Bioquímica, e Biologia.</p

A review of conventional and emerging technologies for hydrogels sterilization

Funding This work was financially supported by Fundaçao ˜ para a Ciˆencia e Tecnologia (FCT), Portugal, through the project STERILAEROGEL – Green method to prepare sterilised biopolymer-based aerogel (POCI01–0145-FEDER-032625) and Strategic Projects FCT-MEC PEst-C/EQB/ UI0102/2019, UIDB/00102/2020 and Programmatic Project UIDP/ 00102/2020 of the CIEPQPF, and UI/05704/2020 of the ciTechCare. C. S. A. Bento acknowledges for PhD grant UI/BD/151008/2021 and M. C. Gaspar acknowledges FCT for the financial support under Scientific Employment Stimulus – Individual and Institutional Calls (CEECIND/ 00527/2017 and CEECINST/00060/2021).Hydrogels are extensively used in the biomedical field, as drug delivery systems, wound dressings, contact lenses or as scaffolds for tissue engineering. Due to their polymeric nature and the presence of high amounts of water in their structure, hydrogels generally present high sensitivity to terminal sterilization. The establishment of an efficient sterilization protocol that does not compromise the functional properties of the hydrogels is one of the challenges faced by researchers when developing a hydrogel for a specific application. Yet, until very recently this aspect was largely ignored in the literature. The present paper reviews the state of literature concerning hydrogels sterilization, compiling the main findings. Conventional terminal sterilization methods (heat sterilization, radiation sterilization, and gas sterilization) as well as emerging sterilization techniques (ozone, supercritical carbon dioxide) are covered. Considerations about aseptic processing are also included. Additionally, and as a framework, hydrogels’ polymeric materials, types of networks, and main biomedical applications are summarily described.info:eu-repo/semantics/publishedVersio

In vitro nematicidal activity of naphthoquinones against the root-lesion nematode Pratylenchus thornei

The root-lesion nematode Pratylenchus thornei is a widely distributed and important parasite of cereals and legumes. As migratory endoparasites, P. thornei are difficult to manage  because they enter and leave host roots and may remain quiescent inside roots or in soil when conditions are unfavourable for plant growth. The number of available nematicides to manage these nematodes is restricted, so new, effective and eco-friendly sustainable management strategies are needed. The effects of naphthoquinones (juglone, 1,4-naphtoquinone and plumbagin) produced by some plants species, including walnut (Juglandaceae), were assessed against P. thornei. An additional treatment of a mixture of juglone and 1,4-naphtoquinone (2:1, w/w), was included because these compounds are frequently found at these propotion in walnut extracts. Juveniles and adult nematodes were exposed to different concentrations of each naphthoquinone and nematode mortality was assessed. Juglone and 1,4-naphthoquinone (at 500 ppm) were more effective than plumbagin, and gave 100% mortality after 24 h of exposure. A synergistic effect was not detected when juglone and 1,4-naphthoquinone (2:1, w/w) were combined. Estimated lethal concentrations causing 50% P. thornei mortality (LC50s) (72 h exposure) were: 134.7 ppm for juglone, 161.2 ppm for 1,4-naphthoquinone, 207.6 ppm for juglone + 1,4-naphthoquinone (2:1, w/w), and 178.8 ppm for plumbagin. This study has demonstrated the nematicidal potential of these naphthoquinones against P. thornei, and has shown that walnut residues may be valuable sources for extraction of these compounds

Transcriptome analysis reveals the high ribosomal inhibitory action of 1,4-naphthoquinone on Meloidogyne luci infective second-stage juveniles

The root-knot nematode (RKN) Meloidogyne luci presents a threat to the production of several important crops. This nematode species was added to the European Plant Protection Organization Alert list in 2017. The scarce availability of efficient nematicides to control RKN and the phasing out of nematicides from the market have intensified the search for alternatives, such as phytochemicals with bionematicidal properties. The nematicidal activity of 1,4-naphthoquinone (1,4-NTQ) against M. luci has been demonstrated; however, knowledge of the potential mode(s) of action of this compound is still scarce. In this study, the transcriptome profile of M. luci second-stage juveniles (J2), the infective stage, in response to 1,4-NTQ exposure was determined by RNA-seq to identify genes and pathways that might be involved in 1,4-NTQ’s mode(s) of action. Control treatments, consisting of nematodes exposed to Tween® 80 (1,4-NTQ solvent) and to water, were included in the analysis. A large set of differentially expressed genes (DEGs) was found among the three tested conditions, and a high number of downregulated genes were found between 1,4-NTQ treatment and water control, reflecting the inhibitory effect of this compound on M. luci, with a great impact on processes related to translation (ribosome pathway). Several other nematode gene networks and metabolic pathways affected by 1,4-NTQ were also identified, clarifying the possible mode of action of this promising bionematicide

Preparation and characterization of flurbiprofen-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microspheres

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microspheres containing flurbiprofen were prepared by an oil-in-water emulsion solvent evaporation method, in order to develop a particulate drug delivery system for localized administration. A response surface method (RSM) using a central composite design was employed to evaluate the effect of the poly(vinyl alcohol) (PVA) (%, w/v) concentration in the aqueous phase and the PHBV concentration in the organic phase (%, w/v) on some of the resulting microspheres properties. The response variables were the encapsulation efficiency (EE), the mean particle size, the width of particle size distribution (expressed by the SPAN value) and the required time for the in vitrorelease of 50% of the encapsulated drug (t50). Second-order polynomial and linear equations were fitted to experimental data and were also used to interpret the results. Results indicated that the concentration of the stabilizer (PVA) showed a highly negative effect on the EE probably due to the increased drug solubility in the aqueous phase as a result of the higher PVA concentrations. Particle diameter mean size increased with the increased polymer concentration while the width of the particle size distribution was found to decrease with the increase of the stabilizer agent. Finally, results indicated that none of the investigated variables presented a significant effect on the t50% values.http://www.informaworld.com/10.1080/0265204070181414

Electrospun Drug-Eluting Fibers for Biomedical Applications

Electrospinning is a simple and versatile method to produce fibers using charged polymer solutions. As drug delivery systems, electrospun fibers are an excellent choice because of easy drug entrapment, high surface area, morphology control and biomimetic characteristics. Various drugs and biomolecules can be easily encapsulated inside or on fiber surface either during electrospinning or through post-processing of the fibers. Multicomponent fibers have attracted special attention because new properties and morphologies can be easily obtained through the combination of different polymers. The factors that affect the drug release such as construct geometry and thickness, diameter and porosity, composition, crystallinity, swelling capacity, drug loading, drug state, drug molecular weight, drug solubility in the release medium, drug–polymer–electrospinning solvent interactions are discussed. Mathematical models of drug release from electrospun fibers are reviewed and strategies to attain zero-order release and control of burst stage are considered. Finally, some results concerning release control in bicomponent fibers composed of poly( ε -caprolactone) and Lutrol F127 (poly(oxyethylene-b-oxypropylene-b-oxyethylene) are presented. The properties of the bicomponent fibers were studied in order to determine the effect of electrospinning processing on crystallinity, hydrophilicity and degradation. Acetazolamide and timolol maleate were loaded in the fibers in different concentrations in order to determine the effect of drug solubility in polymer, drug state, drug loading and fiber composition on morphology, drug distribution and release kinetics. Such electrospun drug eluting fibers can be used as basic elements of various implants and scaffolds for tissue regeneration

Influence of polymer processing technique on long term degradation of poly(ε-caprolactone) constructs

Films, fibers, sponges and disks, based on poly(ε-caprolactone), PCL were prepared using solvent-casting, electrospinning, supercritical fluid processing and melt-compression, respectively. The extent of degradation was determined by measuring the change in morphology, crystallinity and molecular weight (MW). The influence of processing method, MW and drug presence on degradation rate was also evaluated. The different processing techniques produced samples of various morphology and crystallinity. Nevertheless, the differences in degradation rate were not so significant during the advanced stage (18–36 months), while some differences existed during the initial stage (up to 18 months). MW had an important effect on degradation rate, while drug did not. The low MW disks had a degradation rate that was lower by one order of magnitude than high MW constructs

Solubility of Irgacure® 2959 photoinitiator in supercritical carbon dioxide: Experimental determination and correlation

CIBA photoinitiator Irgacure® 2959 is a highly efficient radical photoinitiator for UV curing systems. Furthermore, and due to its proven low cellular toxicity, this photoinitiator can also be employed in the photopolymerization of polymers and copolymers intended for biomedical and tissue engineering applications, not only in conventional pharmaceutically accepted liquid solvents, but also in supercritical CO2 (scCO2). In this work we report the experimental measurement and correlation of the solubility of Irgacure® 2959 in scCO2. Results were obtained using a static analytical method, at 308.2, 318.2 and 328.2 K, and in a pressure range from 10.0 up to 26.0 MPa. Experimental data were correlated with three density-based models (Chrastil, Bartle and Méndez-Santiago-Teja models) and with an equation-of-state (EOS) model: the Peng-Robinson cubic equation of state (PR-EOS) together with the conventional van der Waals mixing and combining rules. Several different sets of solid properties, estimated by different methods available in literature, were used in EOS correlations. The importance of the estimation methods used for the determination of solid properties (namely sublimation pressure) was discussed in terms of correlation results quality.http://www.sciencedirect.com/science/article/B6VMF-4RSRDJ8-1/1/5d7db140e5741dda783b0f8e3875c79