Polyamidoamines: Versatile Bioactive Polymers with Potential for Biotechnological Applications

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L-Arginine-Derived Polyamidoamine Oligomers Bearing at Both Ends beta-Cyclodextrin Units as pH-Sensitive Curcumin Carriers

The aza-Michael polyaddition of L-arginine and N,N′-methylene-bis-acrylamide gives the biocompatible and easily cell-internalized polyamidoamine ARGO7. By controlled synthesis, two ARGO7 oligomers, namely a trimer and a pentamer, bearing acrylamide terminal units, were obtained as precursors of the β-cyclodextrin-end-terminated oligomers P3 and P5, which have been shown to encapsulate curcumin at both pH 7.4 and 4.5. After lyophilization, P3- and P5-curcumin complexes gave stable water solutions. The apparent solubility of encapsulated curcumin was in the range 20–51 μg mL(−1), that is, three orders of magnitude higher than the water solubility of free curcumin (0.011 μg mL(−1)). The drug release profiles showed induction periods both at pH levels 4.5 and 7.4, suggesting a diffusive release mechanism, as confirmed by kinetic studies. The release rate of curcumin was higher at pH 7.4 than at pH 4.5 and, in both cases, it was higher for the P5 complex. Encapsulated curcumin was more photostable than the free drug. Molecular mechanics and molecular dynamics simulations explain at atomistic level the formation of aggregates due to favorable van der Waals interactions. The drug molecules interact with the external surface of carriers or form inclusion complexes with the β-cyclodextrin cavities. The aggregate stability is higher at pH 4.5

Cyclodextrin-Based Nanohydrogels Containing Polyamidoamine Units: A New Dexamethasone Delivery System for Inflammatory Diseases

Glucocorticoids are widely prescribed in treatment of rheumatoid arthritis, asthma, systemic lupus erythematosus, lymphoid neoplasia, skin and eye inflammations. However, well-documented adverse effects offset their therapeutic advantages. In this work, novel nano-hydrogels for the sustained delivery of dexamethasone were designed to increase both bioavailability and duration of the administered drug and reducing the therapeutic dose. Hydrogels are soft materials consisting of water-swollen cross-linked polymers to which the insertion of cyclodextrin (CD) moieties adds hydrophobic drug-complexing sites. Polyamidoamines (PAAs) are biocompatible and biodegradable polymers apt to create CD moieties in hydrogels. In this work, β or γ-CD/PAA nanogels have been developed. In vitro studies showed that a pretreatment for 24–48 h with dexamethasone-loaded, β-CD/PAA nanogel (nanodexa) inhibits adhesion of Jurkat cells to human umbilical vein endothelial cells (HUVEC) in conditions mimicking inflammation. This inhibitory effect was faster and higher than that displayed by free dexamethasone. Moreover, nanodexa inhibited COX-2 expression induced by PMA+A23187 in Jurkat cells after 24–48 h incubation in the 10−8–10−5 M concentration range, while dexamethasone was effective only at 10−5 M after 48 h treatment. Hence, the novel nanogel-dexamethasone formulation combines faster action with lower doses, suggesting the potential for being more manageable than the free drug, reducing its adverse side effects

Take a picture! The role of visual methods in understanding psychiatric patient's everyday life

Understanding the patient's experience of mental illness can foster better support for this population and greater partnership with healthcare professionals. This study aims to explore the application of visual methods in the psychiatric field and, in particular, the experience of people suffering from psychotic disorders because it is still an open question that has not been only partially empirically examined

Polyamidoamine Nanoparticles for the Oral Administration of Antimalarial Drugs

Current strategies for the mass administration of antimalarial drugs demand oral formulations to target the asexual Plasmodium stages in the peripheral bloodstream, whereas recommendations for future interventions stress the importance of also targeting the transmission stages of the parasite as it passes between humans and mosquitoes. Orally administered polyamidoamine (PAA) nanoparticles conjugated to chloroquine reached the blood circulation and cured Plasmodium yoelii-infected mice, slightly improving the activity of the free drug and inducing in the animals immunity against malaria. Liquid chromatography with tandem mass spectrometry analysis of affinity chromatography-purified PAA ligands suggested a high adhesiveness of PAAs to Plasmodium falciparum proteins, which might be the mechanism responsible for the preferential binding of PAAs to Plasmodium-infected erythrocytes vs. non-infected red blood cells. The weak antimalarial activity of some PAAs was found to operate through inhibition of parasite invasion, whereas the observed polymer intake by macrophages indicated a potential of PAAs for the treatment of certain coinfections such as Plasmodium and Leishmania. When fluorescein-labeled PAAs were fed to females of the malaria mosquito vectors Anopheles atroparvus and Anopheles gambiae, persistent fluorescence was observed in the midgut and in other insect's tissues. These results present PAAs as a versatile platform for the encapsulation of orally administered antimalarial drugs and for direct administration of antimalarials to mosquitoes, targeting mosquito stages of Plasmodiu

Poly(amidoamine) Hydrogels as Scaffolds for Cell Culturing and Conduits for Peripheral Nerve Regeneration

Biodegradable and biocompatible poly(amidoamine)-(PAA-) based hydrogels have been considered for different tissue engineering applications. First-generation AGMA1 hydrogels, amphoteric but prevailing cationic hydrogels containing carboxylic and guanidine groups as side substituents, show satisfactory results in terms of adhesion and proliferation properties towards different cell lines. Unfortunately, these hydrogels are very swellable materials, breakable on handling, and have been found inadequate for other applications. To overcome this problem, second-generation AGMA1 hydrogels have been prepared adopting a new synthetic method. These new hydrogels exhibit good biological properties in vitro with satisfactory mechanical characteristics. They are obtained in different forms and shapes and successfully tested in vivo for the regeneration of peripheral nerves. This paper reports on our recent efforts in the use of first-and second-generation PAA hydrogels as substrates for cell culturing and tubular scaffold for peripheral nerve regeneration

Towards epoxidation catalysts for fluorous biphase systems: synthesis and properties of two Mn(III)-tetraarylporphyrins bearing perfluoroalkylamido tails.

wo new Mn(III)-tetraarylporphyrins Mn-1 and Mn-2 bearing one amido-bonded n-C7F15 chain on each meso-aryl group have been synthesized. The presence of four perfluoroalkyl tails strongly influences the solubility of these compounds in common organic solvents, but it is not sufficient to impart solubility in fluorocarbons. The catalytic activity of the new complexes was tested in alkene epoxidations employing aqueous NaOCl as oxygen donor. Results show that Mn-2 is more active than Mn(III)-5,10,15,20-tetrakis-(2,6-dichlorophenyl)porphyrin, one of the most efficient porphyrinic catalysts for hydrocarbon oxygenation