Lorena Tavano

In vitro antitumor activity of methotrexate via pH-sensitive chitosan nanoparticles

Nanoparticles with pH-sensitive behavior may enhance the success of chemotherapy in many cancers by efficient intracellular drug delivery. Here, we investigated the effect of a bioactive surfactant with pH-sensitive properties on the antitumor activity and intracellular behavior of methotrexate-loaded chitosan nanoparticles (MTX-CS-NPs). NPs were prepared using a modified ionotropic complexation process, in which was included the surfactant derived from N(α),N(ε)-dioctanoyl lysine with an inorganic lithium counterion. The pH-sensitive behavior of NPs allowed accelerated release of MTX in an acidic medium, as well as membrane-lytic pH-dependent activity, which facilitated the cytosolic delivery of endocytosed materials. Moreover, our results clearly proved that MTX-CS-NPs were more active against the tumor HeLa and MCF-7 cell lines than the free drug. The feasibilty of using NPs to target acidic tumor extracellular pH was also shown, as cytotoxicity against cancer cells was greater in a mildly acidic environment. Finally, the combined physicochemical and pH-sensitive properties of NPs generally allowed the entrapped drug to induce greater cell cycle arrest and apoptotic effects. Therefore, our overall results suggest that pH-sensitive MTX-CS-NPs could be potentially useful as a carrier system for tumor and intracellular drug delivery in cancer therapy.

Niosomes vs microemulsions: new carriers for topical delivery of Capsaicin.

The development of advanced biomaterials and drug-delivery systems has had a significant impact on our ability to treat several diseases. A new study was performed on niosomal formulations obtained from a mixture of commercial surfactants (Tween 80 and Span 80) to be applied topically for the release of Capsaicin. Capsaicin is the pungent principle of red pepper and it has a variety of pharmacological actions on the cardiovascular, respiratory and nervous systems. Niosomal carriers were prepared using a particular ratio between surfactants, to obtain systems with a specific HLB (10,12,14) and characterized in terms of dimension, morphology and their drug entrapment efficiency. Niosomes were compared to microemulsions prepared from the same surfactants in the same ratio, to evaluate their possible use in transdermal drug delivery. As regards the in vitro percutaneous permeation of Capsaicin from both microemulsions and niosomal formulations, it was carried out using diffusion Franz cells. The results indicate that niosomes could better promote the transdermal delivery of Capsaicin, with respect to microemulsions, even if both carriers could be an effective vehicle for topical delivery of this drug.

Co-encapsulation of antioxidants into niosomal carriers: gastrointestinal release studies for nutraceutical applications.

Recently niosomes have been used as nutraceutical vehicles of functional components, useful in the prevention of many diseases caused by oxidative stress, with the aim to control their delivery into the body and to increase the nutritional quality of food dairy products with which these products can be enriched. We decided to develop novel niosomal formulations containing nutritional supplements such as gallic acid, ascorbic acid, curcumin and quercetin as single agents and in combination, to evaluate the effect of the active molecules co-encapsulation on the physico-chemical properties of the carriers, on their antioxidant properties and capability of releasing the encapsulated materials. Results suggest that the co-encapsulations of gallic acid/curcumin and ascorbic acid/quercetin mix influence their physico-chemical properties and their entrapment efficiencies respect to the formulations containing the single antioxidant; also the antioxidants releases appeared to improve and their combinations resulted in a promoted ability of reducing free radicals, due to a synergic antioxidant action.

Gels of Pluronic F127 and nonionic surfactants from rheological characterization to controlled drug permeation.

The role of nonionic vesicles on the rheological behavior of Pluronic F127 is investigated above the dilute regime and below the cloud point of the nonionic surfactant. F127 is a copolymer possessing sol-gel transition by heating attributed to a phase transition from micellar to cubic. The presence of surfactant vesicles is expected to enhance the compartmentalization of a variety of drugs, independently of their affinity to the solvent. Such entrapment would be suitable for controlled release of the drugs in different applications. We address here a mixed Pluronic-nonionic surfactant system with particular emphasis to the effects of the surfactant on the rheological properties of the Pluronics, and the correlation between these properties and drug release control. The results show that the rheological properties of the mixed system are mainly governed by the behavior of the polymer alone and that the mixed system can be useful to control the percutaneous permeation of a small drug, such as Diclofenac Sodium salt.

Doxorubicin loaded magneto-niosomes for targeted drug delivery

In chemotherapy the magnetic drug targeting to a specific organ or tissue is proposed on the assumption that magnetic fields are harmless to biological systems. In this light we have vehiculated doxorubicin as model drug by novel magneto-niosomes in order to evaluate the physico-chemical properties of the obtained formulations and the in vitro release profile. Tween 60 and Pluronic L64 have been used as surfactants and the formulation cytotoxicity has been performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolum bromide and trypan blue dye esclusion tests. Results show that niosome dimensions and doxorubicin entrapment efficiencies are influenced by bilayer composition. In addition, formulations are able to control the deliver and release of the drug active form in a retarded manner. No additional toxicity, due to the encapsulation of ferrofluid into niosomes core, has been detected.

A novel dextran hydrogel linking trans-ferulic acid for the stabilization and transdermal delivery of vitamin E

Long-term exposure of the skin to UV light causes degenerative effects, which can be minimized by using antioxidant formulations. The major challenge in this regard is that a significant amount of antioxidant should reach at the site for effective photoprotection. However, barrier properties of the skin limit their use. In the present study, vitamin E (alpha-tocopherol) was loaded into a dextran hydrogel containing ferulic moieties, covalently linked, to improve its topical delivery, and also to increase its relative poor stability, which is due to direct exposure to UV light. Methacrylic groups were first introduced onto the dextran polymer backbones, then the obtained methacrylated dextran was copolymerized with aminoethyl methacrylate, and subsequently esterificated with trans-ferulic acid. The new biopolymer was characterized by Fourier transform infrared spectroscopy. The values of content of phenolic groups were determined. Its ability in inhibiting lipid peroxidation in rat liver microsomal membranes induced in vitro by a source of free radicals, that is tert-butyl hydroperoxide, was studied. Hydrogel was also characterized for swelling behaviour, vitamin E loading efficiency, release, and deposition on the rabbit skin. Additionally, vitamin E deposition was compared through hydrogels, respectively, containing and not containing trans-ferulic acid. The results showed that ferulate hydrogel was a more effective carrier in protecting vitamin E from photodegradation than hydrogel without antioxidant moieties. Then antioxidant hydrogel could be of potential use for cosmetic and pharmaceutical purposes as carrier of vitamin E that is an antioxidant that reduces erythema, photoaging, photocarcinogenesis, edema, and skin hypersensitivity associated with exposure to ultraviolet B (UVB) radiation, because of its protective effects.

Role of aggregate size in the hemolytic and antimicrobial activity of colloidal solutions based on single and gemini surfactants from arginine

Cationic colloidal systems composed of arginine based surfactants (single or gemini structures) and membrane additive compounds such as DLPC or cholesterol have been characterized by means of size distribution and zeta-potential measurements. The single or monocatenary surfactant (LAM) as well as the gemini with the shortest spacer chain (C6(LA)2) formed micelles, while aqueous solutions of pure gemini surfactants with longer spacers (C9(LA)2 and C12(LA)2) formed very big aggregates. The addition of phospholipids or cholesterol changed drastically the aggregation behaviour. In the case of LAM and C6(LA)2, the incorporation of additives gave rise to the formation of cationic vesicles. For C9(LA)2 and C12(LA)2, this type of additives promoted the formation of smaller aggregates. All the formulations had positive zeta-potential values and in general exhibited high colloidal stability. We also evaluated the hemolysis and the antimicrobial activity of these systems. The capability of disrupting erythrocyte membranes depends on the hydrophobicity of the molecules and the size of aggregates in the solution. Gemini surfactants with short spacer chains are more hemolytic than their single chain homologue, while gemini surfactants with long spacers are much less hemolytic than their single chain counterpart. Moreover, for the same formulation, the hemolysis depends on the initial concentration of the stock solution used to set up the hemolysis/concentration curve. Results show that small aggregates interact easily with these biological membranes. The alkyl spacer chain and the presence of additives also play an important role in the antimicrobial activity, and, in general, the interaction with bacteria and erythrocytes is affected by the same parameters. The physico-chemical and biological characterization of these systems might be important for several biotechnological applications in which cationic vesicular systems are involved.

Transferrin-Conjugated Pluronic Niosomes as a New Drug Delivery System for Anticancer Therapy

An efficient tumor-targeted niosomal delivery system for the vehiculation of doxorubicin hydrochloride as an anticancer agent was designed. Niosomes were prepared from a mixture of an opportunely modified Pluronic L64 surfactant and cholesterol as a membrane additive and characterized in terms of size and related distribution function and drug entrapment efficiency. After the preparation, transferrin was conjugated to niosomes to produce transferrin (Tf) niosomes, and the cytotoxicity of the final formulation was studied. The specific uptake of Tf niosomes into cells was evaluated via incubation of MCF-7 and MDA-MB-231 cells with fluorescently rhodamine-loaded Tf niosomes for various times and concentration intervals and further investigated by fluorescence microscopy. Results showed that doxorubicin can be easily encapsulated into niosomes, which are regular and spherical in shape. Moreover, transferrin conjugate niosomes demonstrated far greater extents of cellular uptake by MCF-7 and MDA-MB-231 cells, suggesting that they were mainly taken up by transferrin receptor-mediated endocytosis. Doxorubicin-loaded niosome anticancer activity was also achieved against MCF-7 and MDA-MB-231 tumor cell lines, and a significant reduction in viability in a dose- and time-related manner was observed. Finally, our formulation could be potentially useful as a target doxorubicin delivery system in anticancer therapy.

Co-encapsulation of lipophilic antioxidants into niosomal carriers: Percutaneous permeation studies for cosmeceutical applications

Niosomal vesicular systems containing resveratrol, alpha-tocopherol and curcumin as single agents and in combination, were designed with the aim to develop novel cosmeceutical formulations. The effects of antioxidants co-encapsulation on the physico-chemical properties of the carriers, their antioxidant properties and in vitro percutaneous permeation profiles were evaluated. Results showed that the co-encapsulation of resveratrol/curcumin and alpha-tocopherol/curcumin affected the physico-chemical properties of niosomes and the entrapment efficiencies values, respect to the formulations containing the single antioxidant. The antioxidants in vitro percutaneous permeations appeared to be controlled and improved respect to the corresponding free solutions used as control. Moreover the antioxidants combinations resulted in a promoted ability to reduce free radicals, due to a synergic antioxidant action.

Alkyl glucopyranoside-based niosomes containing methotrexate for pharmaceutical applications: Evaluation of physico-chemical and biological properties

We designed novel niosomes based on alkyl glucopyranoside surfactants and containing methotrexate as anticancer drug, to be used in the pharmaceutical field. The effects of surfactants with chains of different length on niosome size and their distribution, drug entrapment efficiencies and in vitro drug release were determined. Systems made of alkyl glucopyranosides and cholesterol form vesicles whose average size scales with the alkyl chains length of such surfactants. Vesicles size ranges between 300 and 500 nm, with low polydispersity index. In addition, the hemolytic activity of alkyl glucopyranosides as surfactant solutions or vesicular formulations was studied and compared, to identify possible structure-activity relationships. High methotrexate entrapment efficiency was obtained, confirming significant interactions between the drug and the niosomal matrices. After 24h the amount of methotrexate released from niosomal formulations is effectively delayed, compared to the free drug in solution. Hemolytic tests show that sugar-based surfactants are more hemolytic the longer is their alkyl chain. When the surfactants are in vesicular form, the reverse behavior holds. It was also inferred that vesicle formation reduces the surfactant toxicity. These niosomal formulations can be used as methotrexate delivery systems in anticancer therapy.