Synthesis of Polymeric Nanoparticles for biomedical delivery applications

Polymeric nanoparticles (PNPs) have attracted considerable interest over the last few years due to their unique properties and behaviors provided by their small size. Such materials could be used in a wide range of applications such as diagnostics and drug delivery. Advantages of PNPs include controlled release, protection of drug molecules and its specific targeting, with concomitant increasing of the therapeutic index. In this work, novel sucrose and cholic acid based PNPs were prepared from different polymers, namely polyethylene glycol (PEG), poly(D,L-lactic-co-glycolic acid) (PLGA) and PLGA-co-PEG copolymer. In these PNP carriers, cholic acid will act as a drug incorporation site and the carbohydrate as targeting moiety. The uptake of nanoparticles into cells usually involves endocytotic processes, which depend primarily on their size and surface characteristics. These properties can be tuned by the nanoparticle preparation method. Therefore, the nanoprecipitation and the emulsion-solvent evaporation method were applied to prepare the PNPs. The influence of various parameters, such as concentration of the starting solution, evaporation method and solvent properties on the nanoparticle size, size distribution and morphology were studied. The PNPs were characterized by using atomic force microscopy (AFM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) to assess their size distribution and morphology. The PNPs obtained by nanoprecipitation ranged in size between 90 nm and 130 nm with a very low polydispersity index (PDI < 0.3). On the other hand, the PNPs produced by the emulsion-solvent evaporation method revealed particle sizes around 300 nm with a high PDI value. More detailed information was found in AFM and SEM images, which demonstrated that all these PNPs were regularly spherical. ζ-potential measurements were satisfactory and evidenced the importance of sucrose moiety on the polymeric system, which was responsible for the obtained negative surface charge, providing colloidal stability. The results of this study show that sucrose and cholic acid based polymeric conjugates can be successfully used to prepare PNPs with tunable physicochemical characteristics. In addition, it provides novel information about the materials used and the methods applied. It is hoped that this work will be useful for the development of novel carbohydrate based nanoparticles for biomedical applications, specifically for targeted drug delivery

Effect of nanomaterials on ageing and moisture damage using the indirect tensile strength test

Environmental conditions as well as traffic loads lead to the deterioration of asphalt pavements during their service life. For this reason, the use of nanomaterials that improve the mixtures behaviour could be interesting. The behaviour of two mixtures made with binder modified with nanoclay and nanoiron, and their strength against ageing and moisture damage is studied. Mixtures have been subjected to ageing by two procedures: extended heating, Long-Term Oven Ageing (LTOA), and ultraviolet (UV) plus rainfall simulation, Tecnico Accelerated Ageing (TEAGE). The results show that nanoclay improves the mixture behaviour against ageing, while nanoiron does against moisture damage.Peer ReviewedPostprint (author's final draft

Orientações de higienização na produção primária de leite e indústria dos lacticínios

Dissertação de Mestrado Integrado em Medicina VeterináriaAo longo dos tempos, o cuidado empregue na higienização dos alimentos revelou-se fundamental para a saúde e bem-estar dos consumidores. O conhecimento do modo como a sujidade e os resíduos, provenientes da manipulação dos alimentos, interagem com os detergentes e diversas soluções de limpeza, é determinante para um correcto planeamento da limpeza e da desinfecção, e sobretudo, para a optimização do resultado final. O leite é um alimento que se apresenta enraizado na cultura portuguesa e constitui a grande matéria-prima para o fabrico dos diversos lacticínios. As suas características próprias requerem que os responsáveis pelo planeamento e execução da higienização das diversas superfícies e equipamentos tenham presentes as diferentes alternativas existentes para a correcta execução destes procedimentos. Os produtores de leite deverão estar conscientes de que a higiene do leite depende da higiene de toda a exploração, da saúde e bem-estar dos animais, e não apenas das condições em que se encontram a sala de ordenha, as instalações adjacentes e do modo como a ordenha é realizada. A indústria dos lacticínios requer um elevado padrão de higiene, que apenas permite o seu cumprimento recorrendo aos melhores e mais recentes métodos de higienização, em conjunto com uma intervenção activa por parte dos técnicos responsáveis. A utilização dos actuais métodos de limpeza Cleaning in Place (CIP) e Open Plant Cleaning (OPC), bem como dos diversos detergentes e produtos comerciais com formulações muito específicas, permite a obtenção de elevados níveis de higiene, uma elevada reprodutibilidade das operações de limpeza e desinfecção, possibilitando em muitos casos a redução dos custos relacionados com estes procedimentos. Em conclusão, higiene é um factor preponderante e decisivo para o sucesso da produção primária de leite e da indústria responsável pela sua transformação.ABSTRACT - Over time, the importance given to food hygiene has proven to be fundamental to the health and welfare of consumers. Knowledge of how dirt and waste, generated while handling food, interact with detergents and various cleaning solutions is crucial for the proper planning of cleaning and disinfection and above all to optimize the final result. Milk is a product that is rooted in the Portuguese culture and is the major raw material used in the production of various dairy products. Its characteristics require that those responsible for planning and implementing cleaning procedures are aware of the various surfaces and equipment options available in such a way that the best implementation of procedures can be achieved. The milk producers should be aware that the hygiene of milk depends on the hygiene of the whole farm, health and welfare of the animals and not only the conditions of the milking room and adjacent areas. In order to comply with a high standard of hygiene the milk industry requires the latest and best methods of cleaning alongside an active intervention by the technician responsible. Current methods such as Cleaning in Place (CIP) and Open Plant Cleaning (OPC) and tailor made detergents and commercial products permit high hygiene levels. In addition, reproducibility of results is also high when reusing these methods and in many cases overall costs can be reduced. To summarize, the hygiene is a dominant and decisive factor for the success of primary and secondary production of milk

Optimizing asphalt mixtures to be heated by microwave

[EN] Over the last ten years the concept of self healing in asphalt mixtures for roads pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. By the moment, there are two mechanisms to promote self healing in asphalt pavement: the incorporation in the asphalt mixtures of capsules containing a rejuvenating agent, or the heating of the pavement, especially the surface layer, to melt the asphalt binder, that gets liquid and refills the cracks in the material, recuperating a part of its initial structural parameters. Probably the most promising method for the in situ heating of the pavements is the radiation by microwaves. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and EAF slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio kwh/kg/ºC in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives was carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self healing of asphalt pavements. References J. Gallego, M.A. del Val, V. Contreras, A. Páez. Use of additives to improve the capacity of bituminous mixtures to be heated by means of microwaves, Materiales de Construcción. Vol. 67, Issue 325, January–March 2017, e110. http://dx.doi.org/10.3989/mc.2017.00416 …The collaboration for this investigation between the University of Lisbon and the Technical University of Madrid was possible thanks to Grant n. PDI-18-0HXIUI-55-QZMWQL for Investigation Stays of Senior Researchers in Foreign Universities and an additional Grant for PhD students by the Agustín of Betancourt Foundation.Gallego, J.; Gulisano, F.; Picado, L.; Crucho, J. (2019). Optimizing asphalt mixtures to be heated by microwave. En AMPERE 2019. 17th International Conference on Microwave and High Frequency Heating. Editorial Universitat Politècnica de València. 348-355. https://doi.org/10.4995/AMPERE2019.2019.9945OCS34835

TADF Dye-Loaded Nanoparticles for Fluorescence Live-Cell Imaging

Thermally activated delayed fluorescence (TADF) molecules offer nowadays a powerful tool in the development of novel organic light emitting diodes due to their capability of harvesting energy from non-emissive triplet states without using heavy-metal complexes. TADF emitters have very small energy difference between the singlet and triplet excited states, which makes thermally activated reverse intersystem crossing from the triplet states back to the singlet manifold viable. This mechanism generates a long-lived delayed fluorescence component which can be explored in the sensing of oxygen concentration, local temperature, or used in time-gated optical cell-imaging, to suppress interference from autofluorescence and scattering. Despite this strong potential, until recently the application of TADF outside lighting devices has been hindered due to the low biocompatibility, low aqueous solubility and poor performance in polar media shown by the vast majority of TADF emitters. To achieve TADF luminescence in biological media, careful selection or design of emitters is required. Unfortunately, most TADF molecules are not emissive in polar media, thus complexation with biomolecules or the formation of emissive aggregate states is required, in order to retain the delayed fluorescence that is characteristic of these compounds. Herein, we demonstrate a facile method with great generalization potential that maintains the photophysical properties of solvated dyes by combining luminescent molecules with polymeric nanoparticles. Using an established swelling procedure, two known TADF emitters are loaded onto polystyrene nanoparticles to prepare TADF emitting nanomaterials able to be used in live-cell imaging. The obtained particles were characterized by optical spectroscopy and exhibited the desired TADF emission in aqueous media, due to the polymeric matrix shielding the dye from solvent polarity effects. The prepared nanoparticles were incubated with live human cancer cells and showed very low cytotoxicity and good cellular uptake, thus making fluorescence microscopy imaging possible at low dye concentrations

Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α-and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger) method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers

Preparation of polycaprolactone nanoparticles via supercritical carbon dioxide extraction of emulsions

Polycaprolactone (PCL) nanoparticles were produced via supercritical fluid extraction of emulsions (SFEE) using supercritical carbon dioxide (scCO2). The efficiency of the scCO2 extraction was investigated and compared to that of solvent extraction at atmospheric pressure. The effects of process parameters including polymer concentration (0.6–10% w/w in acetone), surfactant concentration (0.07 and 0.14% w/w) and polymer-to-surfactant weight ratio (1:1–16:1 w/w) on the particle size and surface morphology were also investigated. Spherical PCL nanoparticles with mean particle sizes between 190 and 350 nm were obtained depending on the polymer concentration, which was the most important factor where increase in the particle size was directly related to total polymer content in the formulation. Nanoparticles produced were analysed using dynamic light scattering and scanning electron microscopy. The results indicated that SFEE can be applied for the preparation of PCL nanoparticles without agglomeration and in a comparatively short duration of only 1 h

Nanotechnology in peripheral nerve repair and reconstruction

The recent progress in biomaterials science and development of tubular conduits (TCs) still fails in solving the current challenges in the treatment of peripheral nerve injuries (PNIs), in particular when disease-related and long-gap defects need to be addressed. Nanotechnology-based therapies that seemed unreachable in the past are now being considered for the repair and reconstruction of PNIs, having the power to deliver bioactive molecules in a controlled manner, to tune cellular behavior, and ultimately guide tissue regeneration in an effective manner. It also offers opportunities in the imaging field, with a degree of precision never achieved before, which is useful for diagnosis, surgery and in the patientâ s follow-up. Nanotechnology approaches applied in PNI regeneration and theranostics, emphasizing the ones that are moving from the lab bench to the clinics, are herein overviewed.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for the financial support provided to Joaquim M. Oliveira (IF/01285/2015) and Joana Silva-Correia (IF/00115/2015) under the program “Investigador FCT”.info:eu-repo/semantics/publishedVersio