Biomedical subjects

Francesca Ungaro

Publications and source records attributed to Francesca Ungaro.

7 recordsLinked to original sources

PubMed2006

Cyclodextrins in the production of large porous particles: development of dry powders for the sustained release of insulin to the lungs.

The aim of this work was to develop dry powders intended for insulin pulmonary delivery. To this purpose, large porous particles (LPP) made of poly(lactide-co-glycolide) (PLGA) were produced by the double emulsion-solvent evaporation technique. Hydroxypropyl-beta-cyclodextrin (HPbetaCD), also known as absorption enhancer for pulmonary protein delivery, was tested as aid excipient to optimize the aerodynamic behaviour of the microparticles. Several microsphere formulations, differing in HPbetaCD and insulin loadings, were produced and their properties compared. A contemporary release of insulin and HPbetaCD from the system can be achieved by selecting appropriate formulation conditions. HPbetaCD-containing LPP with flow properties and dimensions suitable for aerosolization and deposition in deep regions of the lung following inhalation were produced. In conclusion, the developed system turns to be of great potential for the combined delivery of the protein and the adsorption promoter in the respiratory tract.

Chromatography, High Pressure Liquid↗

PubMed2006

Microsphere-integrated collagen scaffolds for tissue engineering: effect of microsphere formulation and scaffold properties on protein release kinetics.

A promising approach to control the time and space distribution of signalling molecules inside tissue engineering scaffolds consists in entrapping biodegradable microspheres releasing the protein locally for long time frames. However, a rational design of microsphere-integrated scaffolds requires the knowledge of protein release profiles directly within the polymeric template. In this work, PLGA microspheres encapsulating rhodamine-labelled bovine serum albumin (BSA-Rhod) as a model protein were produced in different formulation conditions and tested for their release features in solution and in collagen and collagen/hyaluronic acid (HA) scaffolds. BSA-Rhod release profiles from single microspheres in solution and within the scaffold were assessed by using a confocal laser scanning microscopy (CLSM)-assisted method. Results suggest that the same diffusion-erosion process controls BSA-Rhod release from microspheres in solution and collagen. Nonetheless, two main factors contribute protein release within the scaffold, that is water activity in the release environment and transport properties of the protein in the gel. While microsphere formulation mainly controls the induction time necessary to activate protein release, polymer scaffold composition governs the release rate. Thus, the fine regulation of a tissue engineering construct may be obtained by an appropriate combination of microspheres and scaffolds, providing a spatial and temporal control over signalling molecule delivery.

Animals↗

PubMed2005

How cyclodextrin incorporation affects the properties of protein-loaded PLGA-based microspheres: the case of insulin/hydroxypropyl-beta-cyclodextrin system.

The aim of this work was to study the influence of cyclodextrin (CD) incorporation on the properties of protein-loaded poly(lactide-co-glycolide) (PLGA) microspheres, with particular regards to protein release kinetics. To this purpose, insulin-loaded microspheres were prepared by spray-drying emulsion or solution formulations, with or without hydroxypropyl-beta-cyclodextrin (HPbetaCD), and fully characterized for encapsulation efficiency and release kinetics of both insulin and cyclodextrin. Homogeneous populations of spherical microparticles entrapping both insulin and HPbetaCD were obtained. In order to get an insight into insulin/HPbetaCD interactions occurring inside microspheres, Fourier transform infrared (FTIR) analysis in the Amide I region was performed. FTIR spectra of dried microspheres containing HPbetaCD showed a change in insulin secondary structure, attributed to the presence of insulin/HPbetaCD complexes within microspheres. Insulin release was affected by the presence of HPbetaCD depending on the initial formulation conditions. In the case of microspheres prepared from emulsion, cyclodextrin reduced only insulin burst, whereas in the case of microspheres obtained from solution, the overall insulin release rate was slowed down. Combining the release kinetics of HPbetaCD with the FTIR results on hydrated microspheres, it was concluded that the formation of insulin/HPbetaCD complexes inside microspheres is critical to decrease protein diffusivity in the polymer matrix and achieve an effective modulation of protein release rate.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed2005

Enhanced intracellular uptake and inhibition of NF-kappaB activation by decoy oligonucleotide released from PLGA microspheres.

BACKGROUND: Nuclear factor-kappaB (NF-kappaB) transcription factor regulates the expression of genes involved in immune response and inflammation. NF-kappaB activity can be efficiently inhibited by double-stranded oligodeoxynucleotides (ODNs). In the present study, we investigated the potential of poly(DL-lactic-co-glycolic acid) (PLGA) microspheres as delivery system for an ODN against NF-kappaB in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). METHODS: Microspheres encapsulating ODN were prepared by the multiple emulsion/solvent evaporation technique and characterised in terms of size, morphology, encapsulation efficiency and in vitro release profile. In vitro uptake after 4 h and activity of ODN released from microspheres were evaluated in RAW 264.7 macrophages stimulated with LPS for 24, 48 and 72 h. RESULTS: We prepared microspheres with a high encapsulation efficiency showing a very slow and almost constant in vitro release of ODN for up to 1 month. ODN slowly released from microspheres translocated better into LPS-stimulated cells as compared with naked ODN. Incubation of cells with ODN-encapsulating microspheres resulted in a decrease of tumor necrosis factor-alpha (TNF-alpha) and nitrite production, inducible nitric oxide synthase (iNOS) protein expression, as well as NF-kappaB/DNA-binding activity. Similar results were obtained with naked ODN only at about 80 times higher concentrations. CONCLUSIONS: Our results suggest that PLGA microspheres could be a useful tool to improve pharmacokinetics of a ODN decoy to NF-kappaB and may represent a promising strategy to effectively inhibit the transcriptional activity of NF-kappaB in inflammatory process.

Animals↗

PubMed2003

Spectrophotometric determination of polyethylenimine in the presence of an oligonucleotide for the characterization of controlled release formulations.

Polyethylenimine (PEI) is a cationic polymer that can be associated to oligonuclotides to promote their transfection both in vitro and in vivo. The controlled release of oligonucleotide/polyethylenimine complexes from biodegradable systems can result in an increased cellular internalisation of the oligonucleotide and a reduced cytotoxicity of the complex. This effect strongly depends on the amount of PEI loaded in and released from the delivery system. In this work we describe a rapid, sensitive and reproducible spectrophotometric method for the quantitative analysis of PEI by itself or in the presence of an associated oligonucleotide. PEI does not possess chromophores, hence the determination by ordinary spectrophotometry is not possible. However, upon addition of copper (II) ions, PEI forms a dark blue cuprammonium complex that can be detected by UV-vis spectrophotometry. The optimum conditions in terms of optical parameters, copper (II) concentration required for a quantitative PEI complexation, and the most suitable medium for the reaction were ascertained. A linear relationship (r(2)=0.9997) between absorbance and amounts of PEI was found at lambda(max) of 285 nm over the concentration range 5.0-50.0 microg ml(-1). The detection limit (QOD) was 4.0 microg ml(-1). The method was validated for the quantitation of PEI in the presence of an oligonucleotide, which absorbs at 285 nm as well.

Algorithms↗

PubMed2003

Feeding liquid, non-ionic surfactant and cyclodextrin affect the properties of insulin-loaded poly(lactide-co-glycolide) microspheres prepared by spray-drying.

The potential of spray-drying technique for the encapsulation in poly(lactide-co-glycolide) (PLGA) microspheres of bovine insulin, a poorly stable peptide, has been investigated. Insulin-loaded microspheres were prepared by spray-drying different feeding liquids containing insulin and PLGA, that is a S/O dispersion, a W/O emulsion or an acetic acid solution. In the case of the emulsion, insulin was also co-encapsulated with either non-ionic surfactants such as polysorbate 20 and poloxamer 188, or complexing agents such as HPbetaCD. In the microspheres prepared from the acetic acid solution of insulin and PLGA, HPbetaCD was tested. Microspheres containing surfactants were aggregated, whereas good quality particles displaying a mean diameter in the range 12.1-27.9 microm were produced in the other cases. Insulin was efficiently loaded inside microspheres except for S/O formulation (only 22% of total insulin content was entrapped). The impact of the microencapsulation process on insulin chemical and conformational stability was assessed by HPLC, circular dichroism and turbidimetry studies. Under the adopted manufacture conditions, insulin was encapsulated in the native state and its chemical and conformational stability was preserved along the fabrication process. The formulations containing only insulin displayed low burst effects (6-11%), whereas the addition of surfactants resulted in much higher burst effects (49-54%) and faster release rate. The co-encapsulation of HPbetaCD slowed down the overall release rate and, in the case of microspheres prepared from the emulsion, allowed a constant insulin release up to 45 days. The study of insulin stability along the release phase showed that insulin was released in the intact form and un-released insulin was stable inside all the microsphere formulations. We conclude that insulin can be effectively encapsulated in PLGA microspheres by the spray-drying technique. Additives with complexing properties such as HPbetaCD have demonstrated a potential in optimizing the release rate of insulin when used in microspheres prepared from W/O emulsions.

Cyclodextrins↗

PubMedDate not supplied

Long-term release and improved intracellular penetration of oligonucleotide-polyethylenimine complexes entrapped in biodegradable microspheres.

The aim of this work was to design a biodegradable delivery system for oligonucleotides providing both a sustained release and an improved intracellular penetration. To this purpose oligonucleotide/polyethylenimine (ON/PEI) complexes at nitrogen to phosphate (N/P) molar ratios of about 15 or 40 were encapsulated into poly(lactide-co-glycolide) microspheres by the multiple emulsion-solvent evaporation technique. ON/PEI complexes were efficiently entrapped inside microspheres. The introduction of salts within the external aqueous phase allowed an improvement of microsphere characteristics. In particular, the use of sodium chloride led to a reduced microsphere porosity and a more homogeneous ON distribution inside the polymeric matrix. These effects were attributed to the reduced flux of water from the external aqueous phase toward the internal aqueous droplets, due to the osmotic effect of sodium chloride. Both, the reduced porosity and the improved ON distribution inside the matrix, were considered responsible for the lower burst effect and the slower ON release rate from microsphere prepared with sodium chloride. ON/PEI complexes encapsulated inside microspheres were also protected toward enzymatic degradation in fetal calf serum. Interestingly, ON/PEI complexes slowly released from microspheres efficiently penetrated inside HeLa cells and oligonucleotides were preferentially located in the nucleus.

Biodegradation, Environmental↗