Síntese de derivados cíclicos de RGD

Dissertação de mestrado em Química MedicinalNeste trabalho foram sintetizados, com diversos bis-aminoácidos através da reacção de ciclo-adição 1,3-dipolar de Huisgen entre azido- e alquinilaminoácidos e entre alquinilaminoácidos e bis-azidas. Os azido-aminoácidos foram obtidos pelo método de Wong, usando uma transferência diazo entre a azida de trifluorometanossulfonilo e a função amina do respectivo aminoácido. As bis-azidas foram sintetizadas a partir dos respectivos ácidos bis-borónicos com azida de sódio. Os alquinilaminoácidos foram obtidos através do acoplamento da propargilamina à função ácido carboxílico da cadeia principal ou lateral dos aminoácidos ou mediante uma reacção de substituição usando uma β-triazolildesidroalanina. A aplicação de diferentes condições reaccionais levou à síntese dos bis-aminoácidos com bons rendimentos. Foram sintetizados diversos péptidos lineares contendo a sequência arginina-glicinaácido aspártico (RGD), usando a síntese peptídica em fase sólida e uma estratégia que envolve o uso do grupo 9-fluorenilmetoxicarbonilo (Fmoc). Num dos péptidos foi acoplado um bis-aminoácido com o anel 1,2,3-triazole. Outro péptido foi ciclizado por formação de uma ligação amida, obtendo-se um péptido cíclico de RGD, c(Val- Arg[Pbf]-Gly-Asp[OtBu]-Lys[Z]), com um resíduo de lisina protegido ortogonalmente na cadeia lateral, relativamente aos grupos protectores dos resíduos de arginina e ácido aspártico. A reacção 1,3-dipolar de Huisgen também foi aplicada na ciclização de péptidos. Sintetizou-se um péptido linear com dois grupos alquino nos terminais amina e ácido carboxílico. Este péptido foi sintetizado em fase sólida e acoplado ao ácido 5-hexinóico no terminal amina. A propargilamina foi ligada em solução à função ácido carboxílico. A reacção deste péptido com a 1,4-benzenobis-azida permitiu obter um novo péptido cíclico contendo a sequência RGD. Após o tratamento com o ácido trifluoracético (TFA), obteve-se o péptido cíclico desprotegido contendo na sua estrutura dois anéis de 1,2,3-triazole.In this work we have synthesized, in good yields, several bis-amino acids using the Huisgen 1,3-dipolar cycloaddition from azide- and alkynil-amino acids or from alkynilamino acids and bis-azides. The azide-amino acids were obtained from the corresponding amino acids and sodium azide by a diazo transfer using a sulfonyl azide as reported previously by Wong. The bis-azides were synthesized from the corresponding bis-boronic acids by treatment with sodium azide. The synthesis of the alkynil-amino acids was carried out by coupling propargylamine to the carboxylic acid function of amino acids or by a substituition reaction using as substract a β- triazolyldehydroalanine. Several peptides containing the arginine-glycine-aspartic acid (RGD) sequence were prepared using solid phase peptide synthesis (SPPS) and a 9-fluorenylmethoxycarbonyl (Fmoc) strategy. A bis-amino acid with a 1,2,3-triazole ring was coupled to one of the peptides. Another peptide containing a benzyloxycarbonyl protected lysine was cyclized by an amide bond using a head-to-tail strategy. Huisgen 1,3-dipolar cycloaddition was also applied in the cyclization of peptides with the RGD sequence. Thus, a linear peptide with two alkynil groups in the N- and Cterminals was prepared in a combined solid phase and solution strategy. This peptide was cyclized using 1,4-diazidobenzene. After cleavage of the protecting groups the cyclic RGD peptide was obtained and characterized

Enhancing functionalization of health care textiles with gold nanoparticle-loaded hydroxyapatite composites

Hospitals and nursing home wards are areas prone to the propagation of infections and are of particular concern regarding the spreading of dangerous viruses and multidrug-resistant bacteria (MDRB). MDRB infections comprise approximately 20% of cases in hospitals and nursing homes. Healthcare textiles, such as blankets, are ubiquitous in hospitals and nursing home wards and may be easily shared between patients/users without an adequate pre-cleaning process. Therefore, functionalizing these textiles with antimicrobial properties may considerably reduce the microbial load and prevent the propagation of infections, including MDRB. Blankets are mainly comprised of knitted cotton (CO), polyester (PES), and cotton-polyester (CO–PES). These fabrics were functionalized with novel gold-hydroxyapatite nanoparticles (AuNPs-HAp) that possess antimicrobial properties, due to the presence of the AuNPs’ amine and carboxyl groups, and low propensity to display toxicity. For optimal functionalization of the knitted fabrics, two pre-treatments, four different surfactants, and two incorporation processes were evaluated. Furthermore, exhaustion parameters (time and temperature) were subjected to a design of experiments (DoE) optimization. The concentration of AuNPs-HAp in the fabrics and their washing fastness were critical factors assessed through color difference (∆E). The best performing knitted fabric was half bleached CO, functionalized using a surfactant combination of Imerol® Jet-B (surfactant A) and Luprintol® Emulsifier PE New (surfactant D) through exhaustion at 70 ◦C for 10 min. This knitted CO displayed antibacterial properties even after 20 washing cycles, showing its potential to be used in comfort textiles within healthcare environments

New biocompatible peptide-based hydrogels as drug nanocarriers

In this work, several new hydrogelators were developed, containing a Naproxen or a Naphthalene group, and their critical aggregation concentrations were determined by fluorescence. The influence of pH on the aggregation of these molecules was also investigated.Foundation for the Science and Technology (FCT, Portugal), FEDER and QREN for financial support to the Research Centers, CFUM [PEst-C/FIS/UI0607/2013 (FCOMP-01-0124-FEDER-037291)] and CQ/UM [PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)]. FCT is also acknowledged for the PhD grant of H. Vilaça (SFRH/BD/7265/2010)

Biocompatible peptide-based hydrogels as nanocarriers for a new antitumoral drug

In this work, several new hydrogelators were developed, containing a Naproxen or a Naphthalene group. The ability of these hydrogels to act as nanocarriers for an antitumoral drug was investigated.Foundation for the Science and Technology (FCT, Portugal), FEDER and QREN for financial support to the Research Centers, CFUM [Strategic Project Pest-C/FIS/UI0607/2013 (FCOMP-01-0124-FEDER-037291)] and CQ/UM [Strategic Project PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)]. FCT is also acknowledged for the PhD grant of H. Vilaça (SFRH/BD/7265/2010)

Innovation of Textiles through Natural By-Products and Wastes

Nowadays, the competitiveness of the textile industry and the consumers’ interest have been increasing the demand for innovative and functional textiles. Allied to this, sustainable developments are playing an increasingly important role in the textile industry. Such concerns led to a new development strategy based on the valorization of bio-based wastes and by-products of different industries, inserting this in the circular economy paradigm. These bio-based wastes and by-products come from several industries, as the agri-food industry. These resources present an enormous potential for valorization in the textile finish due to their intrinsic properties (antimicrobial, prebiotic, antioxidant activity, among others). This chapter will review the latest innovation and textile product development through different by-products and wastes, their main properties and characteristics and the advantages that they offer to the textile industry

Síntese de novos derivados peptídicos que se autoassociam em hidrogéis nanoestruturados para aplicações biomédicas

Tese de Doutoramento em Ciências (área de especialização em Química)Low molecular weight hydrogelators (LMWHs) are small molecules that selfassemble in water as a result of weak intermolecular forces, and trap water in a three-dimensional structure, thus giving a gel. High water content, biocompatibility and similarity to the extracellular matrix make LMWHs attractive for a wide range of biomedical applications. In recent years, hydrogels of small peptides, especially diand tripeptides, have been developed. These hydrogels are attractive due to their uncomplicated synthetic procedures, chemical variability and potential introduction of biological functionalities. However, the knowledge of the driven forces that govern hydrogelation of small peptides still requires extensive studies. Susceptibility to enzymatic hydrolysis is the main limitation of peptide hydrogels. Replacing natural amino acids by non-proteinogenic analogues is a well established strategy to endow peptides and proteins with proteolytic stability. In this work several dipeptides N-capped with different aromatic moieties, such as naproxen, 2-naphthylacetyl and 1-naphthoyl were synthesized and characterized. All the dipeptides contained one non-proteinogenic dehydroamino acid in the second residue [dehydrophenylalanine ( Phe), dehydroaminobutyric acid ( Abu) or dehydroalanine ( Ala)]. Some of them showed to be biocompatible and resistant to proteases. The dipeptides were tested as hydrogelators, using temperature and pH triggers [addition of hydrochloric acid or D-glucono- -lactone (GdL)]. It was found that only dehydrodipeptides having at least one aromatic amino acid were efficient hydrogelators. Molecular dynamics simulations were used to obtain insights into the underlying molecular mechanism of self-assembly and to rationalize the design of this type of hydrogelators. The results obtained were in excellent agreement with the experimental observations. The characterization of the hydrogels was carried out using transmission electron microscopy (TEM), UV-visible and fluorescence spectroscopies, circular dichroism (CD) and rheology. The dipeptides with N-protecting aromatic moieties organized into high order arrangements in the gel phase. The gels consisted of networks of crosslinked nanofibres with varying widths and densities. Rheology demonstrated that the elasticity and healing properties of the gels were different for each peptide. For the same peptide, the rheological properties depended on factors such as peptide concentration and pH. In this work, the first tryptophan or 1-naphthoyl N-capped dipeptide hydrogelators were described. The latter gave highly elastic hydrogels with low critical gelation concentrations. The hydrogel of naproxen-L-Trp-Z- Phe-OH was used to incorporate non-covalently a potential anti-tumour thieno[3,2-b]pyridine derivative. Fluorescence and FRET measurements indicated that the drug was located in a hydrophobic environment, near or associated with the peptide fibres, demonstrating the possible application of this type of hydrogels as novel drug-nanocarriers. A peptide with a pyridine-2,6-dicarboxamide between two dehydrodipeptides (LPhe- Z- Phe) was also prepared and characterized. The gelation of this peptide was accomplished using a pH trigger. The gels showed characteristics comparable to those of the N-protected dipeptides referred above. The self-assembly of this peptide was also studied in different solvents and in the presence of different metal ions. One of the dipeptide hydrogelators was linked to the bioactive epitope Arg-Gly-Asp (RGD) and its possible application as an extracellular matrix surrogate was tested. The peptide naproxen-L-Ala-Z- Phe-Gly-L-Arg-Gly-L-Asp-Gly-OH gave thermoreversible and self-healing hydrogels at pH 6 and low concentrations. After peptide neutralization, hydrogels were obtained in physiological conditions. Cell toxicity was observed above 0.5 mM, possibly due to the formation of aggregates. A similar peptide having a glutamic acid residue instead of aspartic acid (RGE peptide) was also prepared, and did not showed any toxicity until 1.2 mM, nor aggregate formation. Molecular dynamics simulations showed that the RGD peptide populates only one conformation, while the RGE peptide presents a population with three distinct conformations. Preliminary results obtained in 2D culture of fibroblasts on RGE peptide gels showed cell penetration and adhesion. This result indicates that the hydrogel could be a good matrix for 3D cell culture.Hidrogéis de baixo peso molecular (HBPMs) são constituídos por pequenas moléculas que se autoassociam em água através de interações intermoleculares fracas, e que são capazes de encapsular água numa estrutura tridimensional. Os HBPMs podem ser usados em diversas aplicações biomédicas devido ao seu alto conteúdo de água, à sua biocompatibilidade e à sua semelhança com a matriz extracelular. Nos últimos anos vindo a ser desenvolvidos hidrogéis a partir de pequenos péptidos, em particular di- e tripéptidos. Estes hidrogéis são particularmente interessantes devido à sua fácil preparação, à sua variabilidade estrutural e à possibilidade de introduzir diversos grupos biofuncionais. No entanto, o conhecimento das forças que levam à gelificação destes pequenos péptidos ainda requer estudos adicionais. A suscetibilidade à hidrólise enzimática é o principal obstáculo ao uso generalizado de hidrogéis peptídicos. A substituição de aminoácidos naturais por análogos não proteinogénicos é uma das estratégias mais usadas para conferir estabilidade proteolítica a péptidos e proteínas. Neste trabalho foram sintetizados e caracterizados diversos dipéptidos N-protegidos com grupos aromáticos, tais como o naproxeno, o 2-naftilacetilo e o 1-naftoílo. Todos os péptidos continham um desidroaminoácido no segundo resíduo [desidrofenilalanina ( Phe), ácido desidroaminobutírico ( Abu) ou desidroalanina ( Ala)]. Alguns destes desidrodipéptidos revelaram ser biocompatíveis e resistentes a proteases. A gelificação destes péptidos foi testada utilizando alterações de temperatura e pH [adição de ácido clorídrico ou de D-glucono- -lactona (GdL)]. Apenas os desidrodipéptidos contendo pelo menos um aminoácido aromático originaram hidrogéis. Simulações de dinâmica molecular foram usadas para obter dados sobre o mecanismo molecular de autoassociação e racionalizar o design deste tipo de hidrogéis. Verificou-se que os resultados obtidos estavam em excelente concordância com as observações experimentais. A caracterização dos hidrogéis foi realizada utilizando microscopia eletrónica de transmissão (TEM), espectroscopias UV-visível e de fluorescência, dicroísmo circular (CD) e reologia. Os péptidos com unidades aromáticas N-protetoras formaram estruturas altamente organizadas na fase de gel. Os géis consistiam em redes de nanofibras reticuladas com diferentes espessuras e densidades. A reologia demonstrou que as propriedades de elasticidade e de recuperação dos géis variavam para cada péptido. Para o mesmo péptido, as propriedades reológicas dos seus géis dependiam de fatores tais como a concentração de péptido e o pH. Neste trabalho foram reportados os primeiros hidrogéis de dipéptidos com resíduos de triptofano ou com o grupo N-protetor 1-naftoílo. Os últimos originaram hidrogéis com elevada elasticidade e baixas concentrações críticas de gelificação. Num hidrogel de naproxeno-L-Trp-Z- Phe-OH foi incorporado, não covalentemente, um derivado de tieno[3,2-b]piridina com potencial atividade antitumoral. Os estudos de fluorescência e FRET indicaram que o fármaco se fixou num ambiente hidrofóbico, perto ou associado às fibras do péptido, demonstrando a possível aplicação deste tipo de hidrogéis como novos veículos para a entrega controlada de fármacos. Foi igualmente preparado e caracterizado um péptido com o grupo piridina-2,6- dicarboxamida entre dois desidrodipéptidos (L-Phe-Z- Phe). A gelificação deste péptido foi conseguida através de uma alteração de pH. Os géis apresentaram características comparáveis às dos dipéptidos N-protegidos referidos acima. A autoassociação deste péptido foi também estudada em diferentes solventes e na presença de iões metálicos. Um dos desidrodipéptidos N-protegido com naproxeno foi ligado ao epítopo bioativo Arg-Gly-Asp (RGD) para possível aplicação como substituto da matriz extracelular. O péptido naproxeno-L-Ala-Z- Phe-Gly-L-Arg-Gly-L-Asp-Gly-OH deu origem a hidrogéis termorreversíveis e tixotrópicos a pH 6 e baixas concentrações. Após neutralização do péptido, foram obtidos hidrogéis em condições fisiológicas. Observou-se toxicidade celular acima de 0,5 mM, possivelmente devido à formação de agregados. Foi preparado um péptido análogo contendo um resíduo de ácido glutâmico em vez de ácido aspártico (péptido de RGE) que não mostrou toxicidade até 1,2 mM, nem formação de agregados. Simulações de dinâmica molecular mostraram que o péptido de RGD tem apenas uma conformação preferencial, ao contrário do péptido de RGE (três conformações). Resultados preliminares obtidos em culturas 2D de fibroblastos nos géis de RGE mostraram penetração e adesão celular. Este resultado indica que o hidrogel poderá ser utilizado como substituto da matriz extracelular.Fundação para a Ciência e a Tecnologia (FCT) SFRH/BD/72651/2010PTNMR, Bruker Avance III 400 Univ. MinhoFundação para a Ciência e a Tecnologia (FCT) and FEDER - COMPETE - QREN - EU - CQ/UM[PEst-C/QUI/UI0686/2011 (FCOMP-01-0124-FEDER-022716)

New self-assembled supramolecular hydrogels based on dehydropeptides

Supramolecular hydrogels rely on small molecules that self-assemble in water as a result of the cooperative effect of several relatively weak intermolecular interactions. Peptide-based low molecular weight hydrogelators have attracted enormous interest owing to the simplicity of small molecules combined with the versatility and biocompatibility of peptides. In this work, naproxen, a well known non-steroidal anti-inflammatory drug, was N-conjugated with various dehydrodipeptides to give aromatic peptide amphiphiles that resist proteolysis. Molecular dynamics simulations were used to obtain insight into the underlying molecular mechanism of self-assembly and to rationalize the design of this type of hydrogelators. The results obtained were in excellent agreement with the experimental observations. Only dehydrodipeptides having at least one aromatic amino acid gave hydrogels. The characterization of the hydrogels was carried out using transmission electron microscopy (TEM), circular dichroism (CD), fluorescence spectroscopy and also rheological assays.Thanks are due to Foundation for Science and Technology (FCT) – Portugal, QREN and program FEDER/COMPETE for financial support through Centre of Chemistry (CQ-UM) of University of Minho. FCT is also acknowledged for PhD grants of G. Pereira (SFRH/BD/38766/2007), H. Vilaça (SFRH/BD/72651/2010) and T. G. Castro (SFRH/BD/79195/2011), co-funded by the European Social Fund. The NMR spectrometer Bruker Avance III 400 is part of the Portuguese NMR Network (Rede/1517/RMN/2005) which is also supported by the FCT

Novel dehydropeptide-based magnetogels containing manganese ferrite nanoparticles as antitumor drug nanocarriers

Herein, novel dehydropeptide-based magnetogels, based on the hydrogelators Npx-L-Phe-Z-ΔAbu-OH, Npx-L-Trp-Z-ΔPhe-OH and Npx-L-Ala-Z-ΔPhe-Gly-L-Arg-Gly-L-Asp-Gly-OH and containing manganese ferrite nanoparticles (diameters around 20 nm), were prepared and characterized. TEM and FTIR measurements showed that the magnetogels maintained the fibrous structure of neat hydrogels, with fibres of ca. 20 nm average width (generally in the range 10–30 nm) and a few conformational changes relative to the neat hydrogels. The magnetogels were tested as nanocarriers for two potential fluorescent antitumor drugs: a thienopyridine derivative and the natural compound curcumin. FRET (Förster resonance energy transfer) from the aromatic moieties (energy donors) of gels to the fluorescent drugs (energy acceptors) and fluorescence anisotropy measurements confirmed the incorporation of both drugs into the magnetogel matrices. The transport of both drugs loaded into the magnetogels to membrane models (small unilamellar vesicles) was assessed by FRET between the fluorescent drugs and the dye Nile Red. The magnetogel possessing the RGD sequence was most promising for the delivery of the thienopyridine derivative, whereas three magnetogels were found to be suitable for the delivery of curcumin.UID/QUI/00686/2016; FCT Project PTDC/QUI-QFI/28020/2017 (POCI-01-0145-FEDER-028020); FCT Project PTDC/QUI-QOR/29015/2017 (POCI-01-0145-FEDER-029015)info:eu-repo/semantics/publishedVersio

Chapter Innovation of Textiles through Natural By-Products and Wastes

Nowadays, the competitiveness of the textile industry and the consumers’ interest have been increasing the demand for innovative and functional textiles. Allied to this, sustainable developments are playing an increasingly important role in the textile industry. Such concerns led to a new development strategy based on the valorization of bio-based wastes and by-products of different industries, inserting this in the circular economy paradigm. These bio-based wastes and by-products come from several industries, as the agri-food industry. These resources present an enormous potential for valorization in the textile finish due to their intrinsic properties (antimicrobial, prebiotic, antioxidant activity, among others). This chapter will review the latest innovation and textile product development through different by-products and wastes, their main properties and characteristics and the advantages that they offer to the textile industry