Inulin-Based Polymeric Micelles Functionalized with Ocular Permeation Enhancers: Improvement of Dexamethasone Permeation/Penetration through Bovine Corneas

Ophthalmic drug delivery is still a challenge due to the protective barriers of the eye. A common strategy to promote drug absorption is the use of ocular permeation enhancers, while an innovative approach is the use of polymeric micelles. In the present work, the two mentioned approaches were coupled by conjugating ocular permeation enhancers (PEG2000, carnitine, creatine, taurine) to an inulin-based co-polymer (INU-EDA-RA) in order to obtain self-assembling biopolymers with permeation enhancer properties for the hydrophobic drug dexamethasone (DEX). Inulin derivatives were properly synthetized, were found to expose about 2% mol/mol of enhancer molecules in the side chain, and resulted able to self-assemble at various concentrations by varying the pH and the ionic strength of the medium. Moreover, the ability of polymeric micelles to load dexamethasone was demonstrated, and size, mucoadhesiveness, and cytocompatibility against HCE cells were evaluated. Furthermore, the efficacy of the permeation enhancer was evaluated by ex vivo permeation studies to determine the performance of the used enhancers, which resulted in PEG2000 > CAR > TAU > CRE, while entrapment ability studies resulted in CAR > TAU > PEG2000 > CRE, both for fluorescent-labelled and DEX-loaded micelles. Finally, an increase in terms of calculated Kp and Ac parameters was demonstrated, compared with the values calculated for DEX suspension

Kinetic studies of the interaction between DNA and polycations based on polyasparthylhydrazide

In the present paper, a systematic kinetic study on the interaction between interpolyelectrolytes such as positive-charged polymers and DNA was carried out. In particular, a qualitative-quantitative kinetic investigation on the interaction between copolymers of the α,β-poly(aspartylhydrazide) and DNA calf thymus filaments was performed. This study gives a new model starting from a well known "pseudo-phase model", and permits to give a qualitative explanation about the trends of experimentally observed kinetic constants by varying the concentration of one of the two poly-electrolytes. Moreover, this study permits to verify the dependence of the binding constants KPAHy-CPTA and KDNA from the cationic copolymer (PAHy-CPTA) concentration and from the DNA concentration, respectively, during the formation process of polyplexes, by the kinetic analysis. It was also possible to know the kinetic constants of the complex formation by the proposed kinetic model, both in the aqueous pseudo-phase than in the non-aqueous pseudo-phase formed by the component in excess. From the parameters (a) and (b), information on the kinetic nature of the interaction between these electrolytes were obtained (cooperative and anti-cooperative bond)

Preparation and Characterization of Inulin Coated Gold Nanoparticles for Selective Delivery of Doxorubicin to Breast Cancer Cells

A novel folate-targeted gold-based nanosystem for achieving selectivity towards folate receptor (FR) positive cells is proposed, by virtue of the fact that the FR is a molecularly targeted entity overexpressed in a wide spectrum of solid tumors. A new inulin-folate derivative (INU-FA) has been synthesized to act as coating agent for 40 nm gold nanoparticles. The obtained polymer-coated gold nanoparticles (Au@INU-FA) were characterized in terms of hydrodynamic radius, shape, zeta potential, and aqueous stability and were loaded with doxorubicin (Au@INU-FA/Doxo). Its release capability was tested in different release media. The selectivity of Au@INU-FA/Doxo system towards FRs-positive cancer cells was proved by the differences in the quantitative uptake using human breast cancer MCF7 as FR-positive cells and 16HBE epithelial as noncancer cell line. Furthermore, the folate-mediated uptake mechanism was studied by FRs-blocking experiments. On the whole Au@INU-FA/Doxo was able to be preferentially internalized into MCF7 cells proving a folate-mediated endocytosis mechanism which allowed a higher and selective cytotoxic effect towards cancer cells. The cytotoxicity profile was evaluated on both cancer and noncancer cell lines, displaying that folate-mediated targeting implied advantageous therapeutic effects, such as amplified drug uptake and increased anticancer activity towards MCF7 cancer cells

HYALURONIC ACID DERIVATIVE MICELLES AS OCULAR PLATFORMS TO DRUG RELEASE AND CORNEAL PERMEATION

In traditional ocular formulations, only small amount of the administered drug penetrates the cornea to reach the intraocular tissue. One approach to improve the drug ocular bioavailability was to develop colloidal drug delivery systems. Polymeric micelles seem to be very promising for their capacity to dissolve a variety of hydrophobic drugs by enhancing their water solubility and so their bioavailability. They are able to increase ocular drug permeability due to interact with the complex corneal structure. Considering the advantages to use mucoadhesive polymer to increase drug residence time on the ocular surface, the aim of this work was to prepare hyaluronic acid-based micelles as a platform to release corticosteroids on the ocular surface. Three amphiphilic derivatives of hyaluronic acid (HA), bearing different amount of hexadecylamine chains (C16), were synthesised and characterized. These are able to form micelles by using the co-solvent evaporation method. All HAC16 derivatives have shown the ability of durable mucoadhesive interactions and resulted potentially useful for corticosteroids encapsulation. Drug-loaded micelles were prepared and characterized in term of drug loading amount and particle size. Moreover, the in vitro drug release studies from micellar systems were carried out in comparison with the dissolution profile of the free drug suspension. Cytocompatibility studies also were performed with HCEpiC cells. HAC16b (DDC16mol%=12%) micelles are selected as the best nanosystems, and their capacity to improve the drugs permeability across corneal barrier are evaluated. Thus, the ex vivo permeation studies were conducted using bovine corneas and Franz type diffusion cells

Cross-Linked Hyaluronan Derivatives in the Delivery of Phycocyanin

An easy and viable crosslinking technology, based on the “click-chemistry” reaction copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (click-crosslinking), was applied to graft copolymers of medium molecular weight (i.e., 270 kDa) hyaluronic acid (HA) grafted with ferulic acid (FA) residues bearing clickable propargyl groups, as well as caffeic acid derivatives bearing azidoterminated oligo(ethylene glycol) side chains. The obtained crosslinked materials were characterized from the point of view of their structure and aggregation liability to form hydrogels in a water environment. The most promising materials showed interesting loading capability regarding the antioxidant agent phycocyanin (PC). Two novel materials complexes (namely HA(270)-FA-TEGECCL- 20/PC and HA(270)-FA-HEGEC-CL-20/PC) were obtained with a drug-to-material ratio of 1:2 (w/w). Zeta potential measurements of the new complexes (−1.23 mV for HA(270)-FA-TEGECCL- 20/PC and −1.73 mV for HA(270)-FA-HEGEC-CL-20/PC) showed alterations compared to the zeta potential values of the materials on their own, suggesting the achievement of drug–material interactions. According to the in vitro dissolution studies carried out in different conditions, novel drug delivery systems (DDSs) were obtained with a variety of characteristics depending on the desired route of administration and, consequently, on the pH of the surrounding environment, thanks to the complexation of phycocyanin with these two new crosslinked materials. Both complexes showed excellent potential for providing a controlled/prolonged release of the active pharmaceutical ingredient (API). They also increased the amount of drug that reach the target location, enabling pH-dependent release. Importantly, as demonstrated by the DPPH free radical scavenging assay, the complexation process, involving freezing and freeze-drying, showed no adverse effects on the antioxidant activity of phycocyanin. This activity was preserved in the two novel materials and followed a concentration-dependent pattern similar to pure PC

Polybutylene succinate artificial scaffold for peripheral nerve regeneration

Regeneration and recovery of nerve tissues are a great challenge for medicine, and positively affect the quality of life of patients. The development of tissue engineering offers a new approach to the problem with the creation of multifunctional artificial scaffolds that act on various levels in the damaged tissue, providing physical and biochemical support for the growth of nerve cells. In this study, the effects of the use of a tubular scaffold made of polybutylene succinate (PBS), surgically positioned at the level of a sciatic nerve injured in rat, between the proximal stump and the distal one, was investigated. Scaffolds characterization was carried out by scanning electron microscopy and X-ray microcomputed tomography and magnetic resonance imaging, in vivo. The demonstration of the nerve regeneration was based on the evaluation of electroneurography, measuring the weight of gastrocnemius and tibialis anterior muscles, histological examination of regenerated nerves and observing the recovery of the locomotor activity of animals. The PBS tubular scaffold minimized iatrogenic trauma on the nerve, acting as a directional guide for the regenerating fibers by conveying them toward the distal stump. In this context, neurotrophic and neurotropic factors may accumulate and perform their functions, while invasion by macrophages and scar tissue is hampered

Streptomyces coelicolor Vesicles: Many Molecules To Be Delivered

Streptomyces coelicolor is a model organism for the study of Streptomyces, a genus of Gram-positive bacteria that undergoes a complex life cycle and produces a broad repertoire of bioactive metabolites and extracellular enzymes. This study investigated the production and characterization of membrane vesicles (MVs) in liquid cultures of S. coelicolor M145 from a structural and biochemical point of view; this was achieved by combining microscopic, physical and -omits analyses. Two main populations of MVs, with different sizes and cargos, were isolated and purified. S. coelicolor MV cargo was determined to be complex, containing different kinds of proteins and metabolites. In particular, a total of 166 proteins involved in cell metabolism/differentiation, molecular processing/transport, and stress response were identified in MVs, the latter functional class also being important for bacterial morpho-physiological differentiation. A subset of these proteins was protected from degradation following treatment of MVs with proteinase K, indicating their localization inside the vesicles. Moreover, S. coelicolor MVs contained an array of metabolites, such as antibiotics, vitamins, amino acids, and components of carbon metabolism. In conclusion, this analysis provides detailed information on S. coelicolor MVs under basal conditions and on their corresponding content, which may be useful in the near future to elucidate vesicle biogenesis and functions.IMPORTANCE Streptomycetes are widely distributed in nature and characterized by a complex life cycle that involves morphological differentiation. They are very relevant in industry because they produce about half of all clinically used antibiotics, as well as other important pharmaceutical products of natural origin. Streptomyces coelicolor is a model organism for the study of bacterial differentiation and bioactive molecule production. S. coelicolor produces extracellular vesicles that carry many molecules, such as proteins and metabolites, including antibiotics. The elucidation of S. coelicolor extracellular vesicle cargo will help us to understand different aspects of streptomycete physiology, such as cell communication during differentiation and response to environmental stimuli. Moreover, the capability of these vesicles for carrying different kinds of biomolecules opens up new biotechnological possibilities related to drug delivery. Indeed, decoding the molecular mechanisms involved in cargo selection may lead to the customization of extracellular vesicle content