Federica Rinaldi

Anti-inflammatory activity of novel ammonium glycyrrhizinate/niosomes delivery system: human and murine models.

Today there is a very great deal of interest among members of the global natural products community in investigating new plant constituents. Recent studies demonstrate that liquorice extracts are useful in the treatment of dermatitis, eczema, and psoriasis, with an efficacy comparable to that of corticosteroids. In this work, niosomes made up of surfactants (Tween 85 and Span 20) and cholesterol at various concentrations were prepared to investigate the potential application of niosomes for the delivery of ammonium glycyrrhizinate (AG), useful for the treatment of various inflammatory based diseases. Vesicles were characterized evaluating dimensions, ζ potential, anisotropy, drug entrapment efficiency, stability, cytotoxicity evaluation and skin tolerability. Release profiles of ammonium glycyrrhizinate/niosomes were evaluated in vitro using cellulose membranes. The best formulation was used to evaluate the in vitro/in vivo efficacy of the ammonium glycyrrhizinate/niosomes in murine and human models of inflammation. The AG-loaded non-ionic surfactant vesicles showed no toxicity, good skin tolerability and were able to improve the drug anti-inflammatory activity in mice. Furthermore, an improvement of the anti-inflammatory activity of the niosome delivered drug was observed on chemically induced skin erythema in humans.

Polysorbate 20 vesicles as oral delivery system: In vitro characterization

Non-phospholipid vesicles made with non-ionic surfactants represent a promising alternative to the more widely studied liposomes. The main aim of the present work is to evaluate if vesicles of polysorbate 20 may be used as delivery systems for oral administration of drugs. Then in vitro stability and mucoadhesion studies in simulated gastrointestinal fluids were carried out. The colloidal stability of the surfactant vesicles was determined by size and fluorescence-dequenching assay, while their mucoadhesive properties were evaluated by light-scattering and protein assay. The results of in vitro stability demonstrated that the pHs and enzymes (pepsin and/or pancreatin) of the gastrointestinal fluids had not influence on surfactant vesicle stability. However, in presence of bile salts the nanosize vesicles showed a release of fluorescent marker (about 11% at 2 h and 28% at 4 h), whereas they were stable in size as confirmed by the light scattering experiments. Finally, the in vitro mucoadhesive experiments showed that the capacity of nanovesicles to adsorb mucin was higher at neutral pH than at acidic pH. As a conclusion of these preliminary studies, the surfactant vesicles could be considered a versatile tool for the oral delivery of drugs with poor stability in gastrointestinal tract and low permeability. Nevertheless, further work is required in order to examine the interaction with and/or the transport route through the epithelial cells of the gastrointestinal wall.

Span and Tween neutral and pH-sensitive vesicles: Characterization and in vitro skin permeation

The aim of this work was the preparation, characterization, and comparison of novel pH-sensitive nonphospholipid vesicles (niosomes) from two nonionic surfactants, with different hydrophilic-lipophilic balance values (Tween®20-TW20 = 16.7 and Span®60-SP60 = 4.7). Surfactants were mixed with cholesterol (CHOL) and its derivative, cholesteryl hemisuccinate (CHEMS), as a pH-sensitive molecule. Vesicles were characterized by dynamic light scattering, in order to evaluate their dimensions and vesicle stability, by ζ-potential measurements and by means of electronic microscopy after freeze-fracture. Ibuprofen (IBU) was used as the model drug, and high-performance liquid chromatography analyses were performed to evaluate drug-entrapment efficiency and release in a neutral, acidic environment. The influence of the vesicle composition on skin accumulation and transdermal permeation of IBU across excised hairless rat skin was investigated by using vertical Gummer diffusion cells. When niosomes with SP60 and CHEMS were prepared, there was a statistically significant increase of skin permeation of IBU, while TW20 niosomes did not show statistically significant differences in Papp values without the influence of the vesicle size and charge.

Niosomes Encapsulating Ibuprofen-Cyclodextrin Complexes: Preparation and Characterization

A new delivery system based on ibuprofen-β-cyclodextrin (βCd) complexation and its loading into non-ionic surfactant vesicles (NSVs) was developed to improve ibuprofen therapeutic efficacy in topical formulations. The proposed strategy exploits the well known solubilizing and stabilizing properties of cyclodextrins together with the high tolerability and percutaneous absorption enhancing properties of NSVs. The complexing capacity of Cds in the presence of Ibuprofen in aqueous solution was evaluated by means of phase solubility studies. The technique used to obtain solid ibuprofen-βCd complexes was the co-lyophilization method. The influence of the preparation method on the physicochemical properties of the final product was evaluated by means of Fourier Transform Infrared Spectroscopy and Differential scanning calorimetry studies. Ibuprofen-βCd complexes were included in Tween 20/Cholesterol vesicles and characterized in terms of size, zeta (ζ)-potential, stability, drug entrapment efficiency and drug release. The best ibuprofen-βCd-NSV system exhibited in vitro drug permeation properties significantly improved with respect to those of the plain drug suspension.

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

Surfactant nanocarriers have received considerable attention in the last several years as interesting alternative to classic liposomes. Different pH-sensitive vesicular colloidal carriers based on Tween 20 derivatives, obtained after functionalization of the head groups of the surfactant with natural, or simply modified, amino acids, were proposed as drug nanocarriers. Dynamic light scattering, Small Angle X-ray Scattering, Trasmission Electron Microscopy and fluorescence studies were used for the physico-chemical characterization of vesicles and mean size, size distribution, zeta potential, vesicle morphology and bilayer properties were evaluated. The pH-sensitivity and the stability of formulations, in absence and in presence of foetal bovine serum, were also evaluated. Moreover, the contact between surfactant vesicles and liposomes designed to model the cellular membrane was investigated by fluorescence studies to preliminary explore the potential interaction between vesicle and cell membranes. Experimental findings showed that physico-chemical and technological features of pH-sensitive vesicles were influenced by the composition of the carriers. Furthermore, proposed carriers are able to interact with mimetic cell membrane and it is reasonable to attribute the observed differences in interaction to the architectural/structural properties of Tween 20 derivatives. The findings reported in this investigation showed that a deep and extensive physico-chemical characterization of the carrier is a fundamental step, according to the evidence that the knowledge of nanocarrier properties is necessary to translate its potentiality to in vitro/in vivo applications.

Ammonium glycyrrhizinate-loaded niosomes as a potential nanotherapeutic system for anti-inflammatory activity in murine models

Background Liquorice extracts demonstrate therapeutic efficacy in treating dermatitis, eczema, and psoriasis when compared with corticosteroids. In this work, nonionic surfactant vesicles (niosomes, NSVs) containing polysorbate 20 (Tween 20), cholesterol, and cholesteryl hemisuccinate at different molar concentrations were used to prepare monoammonium glycyrrhizinate (AG)-loaded NSVs. The anti-inflammatory properties of AG-loaded NSVs were investigated in murine models. Methods The physicochemical properties of the NSVs were characterized using dynamic light scattering. The fluidity of the lipid bilayer was evaluated by measuring the fluorescence intensity of diphenylhexatriene. The drug entrapment efficiency of AG was assessed using high-performance liquid chromatography. The physicochemical stability of the NSVs was evaluated as a function of time using dynamic light scattering combined with Turbiscan Lab® Expert analysis. Serum stability was determined by incubating the NSVs with 10% v/v fetal bovine serum. The cytotoxic effects of the NSVs were investigated in human dermal fibroblasts using the Trypan blue dye exclusion assay (for cell mortality) and an MTT assay (for cell viability). Release profiles for the AG-loaded NSVs were studied in vitro using cellulose membranes. NSVs showing the most desirable physicochemical properties were selected to test for in vivo anti-inflammatory activity in murine models. The anti-inflammatory activity of the NSVs was investigated by measuring edema and nociception in mice stimulated with chemical agents. Results NSVs showed favorable physicochemical properties for in vitro and in vivo administration. In addition, they demonstrated long-term stability based on Turbiscan Lab Expert analysis. The membrane fluidity of the NSVs was not affected by self-assembling of the surfactants into colloidal structures. Fluorescence anisotropy was found to be independent of the molar ratios of cholesteryl hemisuccinate and/or cholesterol during preparation of the NSVs. The anti-inflammatory AG drug showed no effect on the stability of the NSVs. In vivo experiments demonstrated that AG-loaded NSVs decreased edema and nociceptive responses when compared with AG alone and empty NSVs. In vitro and in vivo results demonstrated that pH sensitive and neutral NSVs show no statistical significant difference. Conclusion NSVs were nontoxic and showed features favorable for potential administration in vivo. In addition, neutral NSVs showed signs of increased anti-inflammatory and antinociceptive responses when compared with AG.

Novel Tween® 20 derivatives enable the formation of efficient pH-sensitive drug delivery vehicles for human hepatoblastoma

We describe the synthesis, the physicochemical characterization and the biological evaluation of three novel pH-sensitive systems prepared derivatizing polysorbate 20 (Tween 20) with glycine, N-methyl-glycine and N,N-dimethyl-glycine (TW20-GLY, TW20-MMG and TW20-DMG). These derivatives form pH-sensitive vesicles and translocate small molecules into cells. The reported systems are efficient drug delivery systems for human hepatoblastoma cells.

Magnetic force microscopy: Quantitative issues in biomaterials

Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells.

Drug delivery in overcoming the blood–brain barrier: role of nasal mucosal grafting

The blood–brain barrier (BBB) plays a fundamental role in protecting and maintaining the homeostasis of the brain. For this reason, drug delivery to the brain is much more difficult than that to other compartments of the body. In order to bypass or cross the BBB, many strategies have been developed: invasive techniques, such as temporary disruption of the BBB or direct intraventricular and intracerebral administration of the drug, as well as noninvasive techniques. Preliminary results, reported in the large number of studies on the potential strategies for brain delivery, are encouraging, but it is far too early to draw any conclusion about the actual use of these therapeutic approaches. Among the most recent, but still pioneering, approaches related to the nasal mucosa properties, the permeabilization of the BBB via nasal mucosal engrafting can offer new potential opportunities. It should be emphasized that this surgical procedure is quite invasive, but the implication for patient outcome needs to be compared to the gold standard of direct intracranial injection, and evaluated whilst keeping in mind that central nervous system diseases and lysosomal storage diseases are chronic and severely debilitating and that up to now no therapy seems to be completely successful.

Chitosan Glutamate-Coated Niosomes: A Proposal for Nose-to-Brain Delivery

The aim of this in vitro study is to prepare and characterize drug free and pentamidine loaded chitosan glutamate coated niosomes for intranasal drug delivery to reach the brain through intranasal delivery. Mucoadhesive properties and stability testing in various environments were evaluated to examine the potential of these formulations to be effective drug delivery vehicles for intranasal delivery to the brain. Samples were prepared using thin film hydration method. Changes in size and ζ-potential of coated and uncoated niosomes with and without loading of pentamidine in various conditions were assessed by dynamic light scattering (DLS), while size and morphology were also studied by atomic force microscopy (AFM). Bilayer properties and mucoadhesive behavior were investigated by fluorescence studies and DLS analyses, respectively. Changes in vesicle size and ζ-potential values were shown after addition of chitosan glutamate to niosomes, and when in contact with mucin solution. In particular, interactions with mucin were observed in both drug free and pentamidine loaded niosomes regardless of the presence of the coating. The characteristics of the proposed systems, such as pentamidine entrapment and mucin interaction, show promising results to deliver pentamidine or other possible drugs to the brain via nasal administration.