Marco Biondi

Injectable thermally responsive mucoadhesive gel for sustained protein delivery.

Poloxamer thermoresponsive gels are widely explored in controlled drug delivery. Nevertheless, these gels possess inadequate mechanical properties, poor bioadhesiveness, and high permeability to water. To overcome these issues, we blended mucoadhesive hyaluronic acid (HA) with poloxamer analogs. This study aimed to investigate the features affecting the microscopic properties of the gels, which determine their macroscopic properties and capability to control/sustain protein release. Results showed that HA hampers water-poloxamer interactions, thus, strongly influencing physicochemical properties of poloxamer gels. This leads to gels with improved mechanical properties in which the diffusion kinetics of macromolecular active molecules are drastically slowed down. Poloxamer-HA gels can sustain the delivery of proteins, such as insulin, and may allow the modulation of its release kinetics by modifying HA content within the gels in the administration sites in which the active molecule release mechanism is mainly governed by its diffusion.

Amphiphilic hyaluronic acid derivatives toward the design of micelles for the sustained delivery of hydrophobic drugs.

The idea of this study was to combine hyaluronic acid (HA) viscosupplementation and a local/controlled delivery of a hydrophobic anti-inflammatory drug. To this aim, we investigated the ability of an octenyl succinic anhydride (OSA) modified HA (OSA-HA), to act as a solubility enhancer and as a platform for slow release of hydrophobic drug(s). This novel HA derivative could act as a viscosupplementation agent and, for this reason, a rheological study was conducted along with calorimetric analysis. Differential scanning calorimetry (DSC) results revealed that the ability of HA to sequester water is enhanced by the introduction of lipophilic functions within HA molecules, resulting in a decrease of the fraction of free water able to freeze compared to the unmodified HA. Moreover, OSA-HA solutions appear to be an appropriate tool to be used in viscosupplementation therapy owing to their suitable viscoelastic features. Our results indicate that OSA-HA is able to self-assemble into micelles, load a hydrophobic drug and release the active molecule with controlled kinetics. In particular, the analysis of release profiles showed that, in all cases, drug diffusion into the gel is faster compared to gel/drug dissolution, being the dissolution contribution more relevant as the OSA-HA concentration increases.

Curcumin loaded PLGA–poloxamer blend nanoparticles induce cell cycle arrest in mesothelioma cells

The pharmacological potential of curcumin (CURC) is severely restricted because of its low water solubility/absorption, short half-life and poor bioavailability. To overcome these issues, CURC-loaded nanoparticles (NPs) were produced by a double emulsion technique. In particular, NPs were made up of an amphiphilic blend of poloxamers and PLGA to confer stealth properties to the NPs to take advantage of the enhanced permeability and retention (EPR) effect. Different surface properties of NPs made up of bare PLGA and PLGA/poloxamer blend were confirmed by the different interactions of these NPs with serum proteins and also by their ability to be internalized by mesothelioma cell line. The uptake of PLGA/poloxamer NPs induces a persistent block in G0/G1 phase of the cell cycle up to 72 h, thus overcoming the drug tolerance phenomenon, normally evidenced with free CURC.

New Insights into the Mechanisms of the Interactions Between Doxorubicin and the Ion-Exchange Hydrogel DC Bead™ for Use in Transarterial Chemoembolization (TACE)

Ion-exchange microspheres (IEMs) are widely employed in controlled drug delivery of ionic drugs due to their high loading capacity and the possibility to obtain the controlled release of the loaded drug(s) at a specific site. Among IEMs, DC Bead™ are embolic microdevices (100–300 μm diameter) designed for transarterial chemoembolization (TACE) and composed of cross-linked poly(vinyl alcohol) (PVA) hydrogel, bearing anionic sulfonate moieties on the cross-links, and able to bind cationic drugs such as doxorubicin hydrochloride (Dox). Even if DC Bead™ were studied for their release and bulk characteristics, a thorough characterization of these devices is still lacking. In particular, the aim of this work was the determination of bound and free water, Dox distribution within the microdevices and drug–DC Bead™ interactions, in terms of transport features within the device. Compared with previous results, different Dox radial distributions in DC Bead™ were found, and related to bead microsctructure and ion exchange mechanism. Artifacts due to the self-quenching of Dox at high concentration were prevented and the diffusion coefficients of drug-polymer (Dox-ionic sites) evaluated in different sections of the microspheres. Furthermore, DSC results indicated that in the hydrogel either free (bulk) or bound (non-freezable) water could be found, and that no freezing-bound water was present.

Engineering poly(ethylene oxide) buccal films with cyclodextrin: a novel role for an old excipient?

Inspired by the multiple roles cyclodextrins can play in polymeric systems, here we engineered poly(ethylene oxide) (PEO) films with (2-hydroxypropyl)-β-cyclodextrin (CD) as multipurpose ingredient. To shed light on the potential of CD in formulating PEO buccal films for the delivery of poorly water-soluble drugs, we preliminarily assessed thermal and mechanical properties as well as wettability of films prepared at different PEO/CD ratios. PEO/CD platform containing 54% by weight of CD was chosen as the optimized composition since it matched acceptable mechanical properties, in terms of tensile strength and elasticity, with a good wettability. The platform was tested as buccal delivery system for triamcinolone acetonide (TrA), a lipophilic synthetic corticosteroid sparely water soluble. Confocal Raman imaging clearly showed that CD was homogeneously (i.e. molecularly) dispersed in PEO. Nevertheless, homogenous drug distribution in the film without TrA crystallization occurred only in the presence of CD. Finally, CD-containing PEO film placed in simulated buccal fluids provided a useful speed-up of TrA release rate while showing slower dissolution as compared to PEO film. These results, as well as compliance with quality specifications of pharmaceutical manufacturing products, strongly support the soundness of the strategy and prompt toward further applications of PEO/CD films in buccal drug delivery.

Bioactivated collagen-based scaffolds embedding protein-releasing biodegradable microspheres: tuning of protein release kinetics

In tissue engineering, the recapitulation of natural sequences of signaling molecules, such as growth factors, as occurring in the native extracellular matrix (ECM), is fundamental to support the stepwise process of tissue regeneration. Among the manifold of tissue engineering strategies, a promising one is based on the creation of the chrono-programmed presentation of different signaling proteins. This approach is based upon the integration of biodegradable microspheres, loaded with suitable protein molecules, within scaffolds made of collagen and, in case, hyaluronic acid, which are two of the fundamental ECM constituents. However, for the design of bioactivated gel-like scaffolds the determination of release kinetics must be performed directly within the tissue engineering template. In this work, biodegradable poly(lactic-co-glycolic)acid (PLGA) microspheres were produced by the multiple emulsion-solvent evaporation technique and loaded with rhodamine-labelled bovine serum albumin (BSA-Rhod), a fluorescent model protein. The microdevices were dispersed in collagen gels and collagen-hyaluronic acid (HA) semi-interpenetrating networks (semi-IPNs). BSA-Rhod release kinetics were studied directly on single microspheres through confocal laser scanning microscopy (CLSM). To thoroughly investigate the mechanisms governing protein release from PLGA microspheres in gels, BSA-Rhod diffusion in gels was determined by fluorescence correlation spectroscopy (FCS), and water transport through the microsphere bulk was determined by dynamic vapor sorption (DVS). Moreover, the decrease of PLGA molecular weight and glass transition temperature (Tg) were determined by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC), respectively. Results indicate that protein release kinetics and delivery onset strongly depend on the complex interplay between protein transport through the PLGA matrix and in the collagen-based release media, and water sequestration within the scaffolds, related to the scaffold hydrophilicity, which is dictated by HA content. The proper manipulation of all these features may thus allow the obtainment of a fine control over protein sequential delivery and release kinetics within tissue-engineering scaffolds.

Sub-100 nm biodegradable nanoparticles: in vitro release features and toxicity testing in 2D and 3D cell cultures

A big challenge in tumor targeting by nanoparticles (NPs), taking advantage of the enhanced permeability and retention effect, is the fabrication of small size devices for enhanced tumor penetration, which is considered fundamental to improve chemotherapy efficacy. The purposes of this study are (i) to engineer the formulation of doxorubicin-loaded poly(D,L-lactic-co-glycolic acid) (PLGA)-block-poly(ethylene glycol) (PEG) NPs to obtain <100 nm devices and (ii) to translate standard 2D cytotoxicity studies to 3D collagen systems in which an initial step gradient of the NPs is present. Doxorubicin release can be prolonged for days to weeks depending on the NP formulation and the pH of the release medium. Sub-100 nm NPs are effectively internalized by HeLa cells in 2D and are less cytotoxic than free doxorubicin. In 3D, <100 nm NPs are significantly more toxic than larger ones towards HeLa cells, and the cell death rate is affected by the contributions of drug release and device transport through collagen. Thus, the reduction of NP size is a fundamental feature from both a technological and a biological point of view and must be properly engineered to optimize the tumor response to the NPs.

Nanoparticle-Integrated Hydrogels as Multifunctional Composite Materials for Biomedical Applications

This review focuses on the most recent developments in the field of nanocomposite hydrogels intended for biomedical applications. Nanocomposite hydrogels are hydrated polymeric networks with a physically or covalently crosslinked three-dimensional (3D) structure swollen with water, in the presence of nanoparticles or nanostructures. A wide array of nanomaterials (polymeric, carbon-based, metallic, ceramic) can be incorporated within the hydrogel network to obtain reinforced nanocomposite hydrogels. Nanocomposites represent a new class of materials with properties absent in the individual components. In particular, the incorporation of nanomaterials within a polymeric hydrogel network is an attractive approach to tailor the mechanical properties of the hydrogels and/or to provide the nanocomposite with responsiveness to external stimuli.

Surface modified natural zeolite as a carrier for sustained diclofenac release: A preliminary feasibility study

In view of zeolite potentiality as a carrier for sustained drug release, a clinoptilolite-rich rock from California (CLI_CA) was superficially modified with cetylpyridinium chloride and loaded with diclofenac sodium (DS). The obtained surface modified natural zeolites (SMNZ) were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction (XRPD) and laser light scattering (LS). Their flowability properties, drug adsorption and in vitro release kinetics in simulated intestinal fluid (SIF) were also investigated. CLI_CA is a Na- and K-rich clinoptilolite with a cationic exchange ability that fits well with its zeolite content (clinoptilolite=80 wt%); the external cationic exchange capacity is independent of the cationic surfactant used. LS and CLSM analyses have shown a wide distribution of volume diameters of SMNZ particles that, along with their irregular shape, make them cohesive with scarce flow properties. CLSM observation has revealed the localization of different molecules in/on SMNZ by virtue of their chemical nature. In particular, cationic and polar probes prevalently localize in SMNZ bulk, whereas anionic probes preferentially arrange themselves on SMNZ surface and the loading of a nonpolar molecule in/on SMNZ is discouraged. The adsorption rate of DS onto SMNZ was shown by different kinetic models highlighting the fact that DS adsorption is a pseudo-second order reaction and that the diffusion through the boundary layer is the rate-controlling step of the process. DS release in an ionic medium, such as SIF, can be sustained for about 5h through a mechanism prevalently governed by anionic exchange with a rapid final phase.

Biocompatible nanoparticles sensing the matrix metallo-proteinase 2 for the on-demand release of anticancer drugs in 3D tumor spheroids

The balance between dose-dependent tolerability, effectiveness and toxicity of systemically administered antitumor drugs is extremely delicate. This issue highlights the striking need for targeted release of chemotherapeutic drugs within tumors. In this work, a smart strategy of drug targeting to tumors relying upon biodegradable/biocompatible nanoparticles releasing cytotoxic drugs after sensing physiological variations intrinsic to the very nature of tumor tissues is exploited. Here, the well-known over-expression of matrix metallo-proteinase 2 (MMP2) enzyme in tumors has been chosen as a trigger for the release of a cytotoxic drug. Nanoparticles made up of a biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA)--block--polyethylene glycol (PEG) copolymer (namely PELGA), blended with a tumor-activated prodrug (TAP) composed of a MMP2-sensitive peptide bound to doxorubicin (Dox) and to PLGA chain have been produced. The obtained devices are able to release Dox specifically upon MMP2 cleavage of the TAP. More interestingly, they can sense the differences in the expression levels of endogenous MMP2 protein, thus modulating drug penetration within a three-dimensional (3D) tumor spheroid matrix, accordingly. Therefore, the proposed nanoparticles hold promise as a useful tool for in vivo investigations aimed at an improved therapeutic efficacy of the conjugated drug payload.