Controlled Release of H2S from Biomimetic Silk Fibroin-PLGA Multilayer Electrospun Scaffolds.

The possibility of incorporating H2S slow-release donors inside biomimetic scaffolds can pave the way to new approaches in the field of tissue regeneration and anti-inflammatory treatment. In the present work, GYY4137, an easy-to-handle commercially available Lawesson's reagent derivative, has been successfully incorporated inside biomimetic silk fibroin-based electrospun scaffolds. Due to the instability of GYY4137 in the solvent needed to prepare silk fibroin solutions (formic acid), the electrospinning of the donor together with the silk fibroin turned out to be impossible. Therefore, a multilayer structure was realized, consisting of a PLGA mat containing GYY4137 sandwiched between two silk fibroin nanofibrous layers. Before their use in the multilayer scaffold, the silk fibroin mats were treated in ethanol to induce crystalline phase formation, which conferred water-resistance and biomimetic properties. The morphological, thermal, and chemical properties of the obtained scaffolds were thoroughly characterized by SEM, TGA, DSC, FTIR, and WAXD. Multilayer devices showing two different concentrations of the H2S donor, i.e., 2 and 5% w/w with respect to the weight of PLGA, were analyzed to study their H2S release and biological properties, and the results were compared with those of the sample not containing GYY4137. The H2S release analysis was carried out according to an "ad-hoc" designed procedure based on a validated high-performance liquid chromatography method. The proposed analytical approach demonstrated the slow-release kinetics of H2S from the multilayer scaffolds and its tunability by acting on the donor's concentration inside the PLGA nanofibers. Finally, the devices were tested in biological assays using bone marrow-derived mesenchymal stromal cells showing the capacity to support cell spreading throughout the scaffold and prevent cytotoxicity effects in serum starvation conditions. The resulting devices can be exploited for applications in the tissue engineering field since they combine the advantages of controlled H2S release kinetics and the biomimetic properties of silk fibroin nanofibers.

A new melatonin oral delivery platform based on orodispersible films containing solid lipid microparticles.

An innovative delivery system for melatonin, based on the incorporation of solid lipid microparticles in orodispersible films (ODFs) made of maltodextrin, was designed and developed. Lipid microparticles at two different melatonin concentrations (10 and 20% w/w) were produced by the spray congealing technology using two different lipid carrier (tristearin and hydrogenated castor oil) and characterized in terms of size, solid state, drug loading and drug release pattern. Tristearin microparticles were discarded due to a polymorphic modification of the carrier. The incorporation of hydrogenated castor oil microparticles in ODFs by using the casting method did not alter significantly the shape and dimension of the microparticles and the mechanical properties (elasticity and strength) of the films, which remained acceptable for manufacturing and handling. The in vitro release studies performed in saliva, gastric and intestinal simulated media on ODFs containing melatonin loaded in hydrogenated castor oil microparticles revealed the possibility to combine with an immediate release of the drug and a sustained release over at least 5 h period. In conclusion, the proposed drug delivery system maintains the advantages of ODFs, i.e. the suitability to be swallowed without water, and permits the tuning of drug release according to the clinical needs by modulating the ratio of free and microencapsulated drug in the ODF.

Spray congealing: a versatile technology for advanced drug-delivery systems.

Spray congealing is a low cost, simple and versatile method to produce microparticles without the use of organic or aqueous solvent. This review provides a detailed picture of the pharmaceutical applications of this technology, with an overview of the spray-congealed-based drug-delivery systems. First, the basic principles and equipment of spray congealing technology are presented. Then, representative examples of the drug-delivery systems are examined and critically discussed. Emphasis is given on the role of formulation variables, together with practical considerations for formulation design. In addition, the current status of the industrial applications of this technology within the pharmaceutical field is examined. The final part points out benefits, limitations and future perspectives of this technology in drug delivery.

Non-equilibrium atmospheric pressure plasma as innovative method to crosslink and enhance mucoadhesion of econazole-loaded gelatin films for buccal drug delivery.

In this paper we developed an innovative, effective and rapid one-step approach to crosslink mucoadhesive gelatin films for buccal drug delivery. The method, which involves the application of non-equilibrium pressure plasma for 3 or 5 minutes/side, was compared with a classical approach based on the use of a chemical crosslinking agent, namely genipin. Econazole nitrate (ECN), an imidazole antifungal agent used for the treatment of skin infections and mucosal candidiasis, was selected as model drug. X-Ray Diffraction characterization performed on the drug-containing gelatin films revealed that ECN undergoes to a topotactic transformation into Econazole (EC) immediately after mixing with gelatin suggesting the occurrence of an acid-base reaction between drug and gelatin during film processing. Plasma treatment, as well as genipin crosslinking, did not provoke any further variation of EC structure. However, plasma exposure significantly improved films adhesiveness and allowed to reach mucoadhesive strength values more than double with respect to those obtained with genipin, ascribable to the presence of polar and hydrophilic groups on the plasma treated film's surface. A residence time of at least 48 h was obtained by properly selecting the plasma exposure times. These results, together with the in-vitro data showing retention of antifungal efficacy against a strain of Candida albicans, demonstrated that plasma treatment was a valid and rapid alternative, easy to scale-up, to chemical crosslinking methods for the production of highly mucoadhesive gelatin-based films.

Development of a new device for ultrasensitive electrochemiluminescence microscopy imaging.

Electrochemiluminescence (ECL) is widely used in biosensors and immunoassays thanks to the high sensitivity and specificity of the electrochemically triggered luminescence signal. So far, no applications have been reported on the use of ECL as a probe for ultrasensitive low-light microscope imaging. This work reports the development of a new transparent electrochemical cell for ECL imaging suitable for single cell analysis. The system is based on the use of a microscope placed in a dark box equipped with a CCD camera and a potentiostat. Transparent conducting glass coated with fluorine-doped tin oxide (FTO) has been used, and a three electrode configuration has been designed. The electrochemical cell was optimized using 8 microm diameter polystyrene beads coated with a Ru(bpy)(3)(2+) complex in order to simulate living cells. The Ru(bpy)(3)(2+) immobilized on the microbeads can be imaged and quantified at a concentration as low as 1 x 10(-19) mol/microm(2). Microscope imaging showed that the ECL signal was detected only in correspondence to the beads present on the electrode surface, and the probe could be accurately localized with a spatial resolution of 0.4 microm. The new ECL imaging device can be used in conjunction with other chemiluminescence-based imaging methods for ultrasensitive multiplex imaging on cells and tissues.

Amphiphilic porphyrin film on glass as a simple and selective solid-state chemosensor for aqueous Hg2+.

Deposition of amphiphilic porphyrin derivatives occurs spontaneously on silanised glass surfaces, in a controlled fashion. The resulting porphyrin films show appreciable fluorescence emission. This emission can be effectively quenched by immersion of the slides into a diluted solution of Hg(2+) (microM concentration). The initial intensity can be restored by washings with a solution of N,N,N',N'-tetrakis(2-pyridilmethyl)ethylenediammine with no loss of efficiency. A remarkable selectivity is featured toward the detection of Hg(2+) over Cu(2+), Cd(2+), Pb(2+) and Zn(2+) counterparts. This protocol can be extended to a flow-through apparatus. The presented results are of importance for the achievement of a solid-state chemosensor for mercuric ions, at micromolar concentration, in water.