PEI-Engineered Lipid@PLGA Hybrid Nanoparticles for Multimodal Delivery of Antigens and Immune Adjuvants to the Respiratory Mucosa.

Antigen delivery via respiratory mucosal surfaces is an interesting needle-free option for vaccination. Nonetheless, it demands for the design of especially tailored formulations. Here, lipid/poly(lactic-co-glycolic) acid (PLGA) hybrid nanoparticles (hNPs) for the combined delivery of an antigen, ovalbumin (Ova), and an adjuvant, synthetic unmethylated cytosine-phosphate-guanine oligodeoxynucleotide (CpG) motifs, is developed. A panel of Ova/CpG-loaded lipid@PLGA hNPs with tunable size and surface is attained by exploiting two lipid moieties, 1,2 distearoil-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG) and monophosphoryl lipid A (MPLA), with or without polyethyleneimine (PEI). It is gained insights on the lipid@PLGA hNPs through a combination of techniques to analytically determine the specific moiety on the surface, the spatial distribution of the components and the internal structure of the nanoplatforms. The collected results suggest that PEI plays a role of paramount importance not only in promoting in vitro antigen escape from lysosomes and enhancing antigen cross-presentation, but also in determining the arrangement of the moieties in the final architecture of the hNPs. Though multicomponent PEI-engineered lipid@PLGA hNPs turn out as a viable strategy for delivery of antigens and adjuvant to the respiratory mucosa, tunable nanoparticle features are achievable only through the optimal selection of the components and their relative amounts.

State-of-the-Art Review on Inhalable Lipid and Polymer Nanocarriers: Design and Development Perspectives.

Nowadays, the interest in research towards the local administration of drugs via the inhalation route is growing as it enables the direct targeting of the lung tissue, at the same time reducing systemic side effects. This is of great significance in the era of nucleic acid therapeutics and personalized medicine for the local treatment of severe lung diseases. However, the success of any inhalation therapy is driven by a delicate interplay of factors, such as the physiochemical profile of the payload, formulation, inhalation device, aerodynamic properties, and interaction with the lung fluids. The development of drug delivery systems tailored to the needs of this administration route is central to its success and to revolutionize the treatment of respiratory diseases. With this review, we aim to provide an up-to-date overview of advances in the development of nanoparticulate carriers for drug delivery to the lung tissue, with special regard concerning lipid and polymer-based nanocarriers (NCs). Starting from the biological barriers that the anatomical structure of the lung imposes, and that need to be overcome, the current strategies to achieve efficient lung delivery and the best support for the success of NCs for inhalation are highlighted.

Enhancing transmucosal delivery of CBD through nanoemulsion: in vitro and in vivo studies.

Cannabidiol (CBD) has gained significant attention as a complementary and alternative medicine due to its promising therapeutic properties. However, CBD faces obstacles when administered orally due to its poor solubility in water, leading to limited absorption into the bloodstream and low and variable bioavailability. Therefore, the development of innovative delivery approaches that can enhance CBD's bioavailability, facilitate administration, and promote patient adherence is crucial. We propose a new approach for buccal delivery of CBD based on a self-assembling nanoemulsion (NE) made of a mixture of surfactants (Tween 80 and Labrasol) and medium chain triglycerides (MCTs). The NE formulation showed properties suitable for buccal administration, including appropriate size, CBD content, and surface properties, and, if compared to a CBD-MCT solution, it exhibited better control of administered doses, faster dissolution in buccal medium, and enhanced stability. The CBD-NE effectively released its active load within 5 h, remained stable even when diluted in simulated buccal fluids, and could be easily administered through a commercially available spray, providing consistent and reproducible doses of NE with optimized properties. In vitro permeation studies demonstrated that the CBD-NE facilitated swift and consistent permeation through the buccal mucosa, resulting in a higher concentration in the acceptor compartment compared to CBD-MCT. Furthermore, the in vivo study in mice showed that a single buccal administration of CBD-NE led to a quicker onset of action than a CBD solution in MCT, while maintaining the same plasma levels over time and leading to typically higher plasma concentrations compared to those usually achieved through oral administration. In conclusion, our CBD-NE represents a promising alternative formulation strategy for buccal CBD administration, overcoming the challenges associated with conventional formulations such as variable bioavailability and low control of administered doses.

The Questionable Quality Profile of Food Supplements: The Case of Red Yeast Rice Marketed Products.

Food supplements (FS) containing red yeast rice (RYR) are largely employed to reduce lipid levels in the blood. The main ingredient responsible for biological activity is monacolin K (MoK), a natural compound with the same chemical structure as lovastatin. Concentrated sources of substances with a nutritional or physiological effect are marketed in "dose" form as food supplements (FS). The quality profile of the "dosage form" of FS is not defined in Europe, whereas some quality criteria are provided in the United States. Here, we evaluate the quality profile of FS containing RYR marketed in Italy as tablets or capsules running two tests reported in The European Pharmacopoeia 11 Ed. and very close to those reported in the USP. The results highlighted variations in dosage form uniformity (mass and MoK content) compliant with The European Pharmacopoeia 11 Ed. specifications, whereas the time needed for disintegrating tablets was longer for 44% of the tested samples. The bioaccessibility of MoK was also investigated to obtain valuable data on the biological behaviour of the tested FS. In addition, a method for citrinin (CIT) determination was optimized and applied to real samples. None of the analyzed samples demonstrated CIT contamination (LOQ set at 6.25 ng/mL). Considering the widespread use of FS, our data suggest that greater attention should be paid by fabricants and regulatory authorities to ensure the quality profile and the safe consumption of marketed products.

Pulmonary Safety Profile of Esc Peptides and Esc-Peptide-Loaded Poly(lactide-co-glycolide) Nanoparticles: A Promising Therapeutic Approach for Local Treatment of Lung Infectious Diseases.

In recent years, we have discovered Esc(1-21) and its diastereomer (Esc peptides) as valuable candidates for the treatment of Pseudomonas lung infection, especially in patients with cystic fibrosis (CF). Furthermore, engineered poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) were revealed to be a promising pulmonary delivery system of antimicrobial peptides. However, the "ad hoc" development of novel therapeutics requires consideration of their stability, tolerability, and safety. Hence, by means of electrophysiology experiments and preclinical studies on healthy mice, we demonstrated that neither Esc peptides or Esc-peptide-loaded PLGA NPs significantly affect the integrity of the lung epithelium, nor change the global gene expression profile of lungs of treated animals compared to those of vehicle-treated animals. Noteworthy, the Esc diastereomer endowed with the highest antimicrobial activity did not provoke any pulmonary pro-inflammatory response, even at a concentration 15-fold higher than the efficacy dosage 24 h after administration in the free or encapsulated form. The therapeutic index was ≥70, and the peptide was found to remain available in the bronchoalveolar lavage of mice, after two days of incubation. Overall, these studies should open an avenue for a new up-and-coming pharmacological approach, likely based on inhalable peptide-loaded NPs, to address CF lung disease.

Boosting lung accumulation of gallium with inhalable nano-embedded microparticles for the treatment of bacterial pneumonia.

The potential of intra-venous gallium nitrate (GaN) administration against Pseudomonas aeruginosa pneumonia was recently demonstrated in mice and in cystic fibrosis (CF) patients. Likewise, the added value of direct lung delivery of Ga(III) has been shown in rats. Therefore, the design of a drug delivery system specifically engineered for Ga(III) inhalation is imperative to improve its accumulation in lungs. To this purpose, Ga(III) was efficiently encapsulated into hyaluronic acid/chitosan nanoparticles (Ga_HA/CS NPs), whose features were tuned to facilitate access to the target by overcoming mucus and biofilm surrounding bacteria. Then, to improve in vivo lung deposition, Ga_HA/CS NPs were engineered into mannitol-based NEM (Ga_Man NEM). The powders showed optimal in vitro aerosol performance, and sustained release kinetics in lung lining fluids. Moreover, good tolerability and antimicrobial properties were shown in vitro. Intratracheal insufflation of Ga_Man NEM in rats resulted in a significant improvement of Ga(III) persistence in the lungs coupled to a lower Ga(III) concentration in plasma and urine, compared to GaN solution. Noteworthy, the developed formulation significantly modifies the unfavorable Ga(III) kinetic increasing the Ga(III) to the lung and preventing Ga(III) accumulation in the kidney, key responsible for adverse effects, conclusively demonstrating the benefit of Ga_Man NEM to exploit the therapeutic effect of Ga(III) via inhalation route.

Hybrid Lipid/Polymer Nanoparticles to Tackle the Cystic Fibrosis Mucus Barrier in siRNA Delivery to the Lungs: Does PEGylation Make the Difference?

Inhaled siRNA therapy has a unique potential for treatment of severe lung diseases, such as cystic fibrosis (CF). Nevertheless, a drug delivery system tackling lung barriers is mandatory to enhance gene silencing efficacy in the airway epithelium. We recently demonstrated that lipid-polymer hybrid nanoparticles (hNPs), comprising a poly(lactic-co-glycolic) acid (PLGA) core and a lipid shell of dipalmitoyl phosphatidylcholine (DPPC), may assist the transport of the nucleic acid cargo through mucus-covered human airway epithelium. To study in depth the potential of hNPs for siRNA delivery to the lungs and to investigate the hypothesized benefit of PEGylation, here, an siRNA pool against the nuclear factor-κB (siNFκB) was encapsulated inside hNPs, endowed with a non-PEGylated (DPPC) or a PEGylated (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) or DSPE-PEG) lipid shell. Resulting hNPs were tested for their stability profiles and transport properties in artificial CF mucus, mucus collected from CF cells, and sputum samples from a heterogeneous and representative set of CF patients. Initial information on hNP properties governing their interaction with airway mucus was acquired by small-angle X-ray scattering (SAXS) studies in artificial and cellular CF mucus. The diffusion profiles of hNPs through CF sputa suggested a crucial role of lung colonization of the corresponding donor patient, affecting the mucin type and content of the sample. Noteworthy, PEGylation did not boost mucus penetration in complex and sticky samples, such as CF sputa from patients with polymicrobial colonization. In parallel, in vitro cell uptake studies performed on mucus-lined Calu-3 cells grown at the air-liquid interface (ALI) confirmed the improved ability of non-PEGylated hNPs to overcome mucus and cellular lung barriers. Furthermore, effective in vitro NFκB gene silencing was achieved in LPS-stimulated 16HBE14o- cells. Overall, the results highlight the potential of non-PEGylated hNPs as carriers for pulmonary delivery of siRNA for local treatment of CF lung disease. Furthermore, this study provides a detailed understanding of how distinct models may provide different information on nanoparticle interaction with the mucus barrier.

Alcohol-Based Hand Sanitizers: Does Gelling Agent Really Matter?

Hand hygiene, social distancing, and face covering are considered the first protection against Coronavirus spreading. The high demand during the COVID-19 emergency has driven a frenetic production and marketing of hand sanitizer gels. Nevertheless, the effect of the gelling agent and its amount on the effectiveness of alcohol-based hand sanitizers (ABHSs) needs to be clarified. We presented a systematic study on the effect of the characteristics and concentration of the most employed excipients on the properties and antimicrobial activity of ABHSs. Three different gelling agents, carbopol, hydroxypropylmethylcellulose (HPMC), and hydroxyethylcellulose (HEC), at four different concentrations were used to prepare ABHSs. Viscosity, spreadability, delivery from commercial dispensers, evaporation rate, rubbing time, and hand distribution of the ABHSs were then explored. Biocidal activity of selected ABHSs was evaluated in vitro on ATCC and clinical strains. The studied ABHS can be considered bioactive and comfortable. Nevertheless, the cellulose polymers and ethanol interactions led to a slight but significant reduction in the biocidal activity compared with carbopol-based formulations. Our results underline the importance of the gelling agent properties and support the choice of carbopol as one of the best thickener agents in ABHS formulations.

Inhalable Polymeric Nanoparticles for Pulmonary Delivery of Antimicrobial Peptide SET-M33: Antibacterial Activity and Toxicity In Vitro and In Vivo.

Development of inhalable formulations for delivering peptides to the conductive airways and shielding their interactions with airway barriers, thus enhancing peptide/bacteria interactions, is an important part of peptide-based drug development for lung applications. Here, we report the construction of a biocompatible nanosystem where the antimicrobial peptide SET-M33 is encapsulated within polymeric nanoparticles of poly(lactide-co-glycolide) (PLGA) conjugated with polyethylene glycol (PEG). This system was conceived for better delivery of the peptide to the lungs by aerosol. The encapsulated peptide showed prolonged antibacterial activity, due to its controlled release, and much lower toxicity than the free molecule. The peptide-based nanosystem killed Pseudomonas aeruginosa in planktonic and sessile forms in a dose-dependent manner, remaining active up to 72 h after application. The encapsulated peptide showed no cytotoxicity when incubated with human bronchial epithelial cells from healthy individuals and from cystic fibrosis patients, unlike the free peptide, which showed an EC50 of about 22 µM. In vivo acute toxicity studies in experimental animals showed that the peptide nanosystem did not cause any appreciable side effects, and confirmed its ability to mitigate the toxic and lethal effects of free SET-M33.

Assisting PNA transport through cystic fibrosis human airway epithelia with biodegradable hybrid lipid-polymer nanoparticles.

Cystic fibrosis (CF) is characterized by an airway obstruction caused by a thick mucus due to a malfunctioning Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. The sticky mucus restricts drugs in reaching target cells limiting the efficiency of treatments. The development of new approaches to enhance drug delivery to the lungs represents CF treatment's main challenge. In this work, we report the production and characterization of hybrid core-shell nanoparticles (hNPs) comprising a PLGA core and a dipalmitoylphosphatidylcholine (DPPC) shell engineered for inhalation. We loaded hNPs with a 7-mer peptide nucleic acid (PNA) previously considered for its ability to modulate the post-transcriptional regulation of the CFTR gene. We also investigated the in vitro release kinetics of hNPs and their efficacy in PNA delivery across the human epithelial airway barrier using an ex vivo model based on human primary nasal epithelial cells (HNEC) from CF patients. Confocal analyses and hNPs transport assay demonstrated the ability of hNPs to overcome the mucus barrier and release their PNA cargo within the cytoplasm, where it can exert its biological function.

Mucoadhesive zein/beta-cyclodextrin nanoparticles for the buccal delivery of curcumin.

Herein, we have developed sprayable dispersions of mucoadhesive nanoparticles (NPs) made of zein, a hydrophobic plant-based protein, for the buccal delivery of curcumin (CUR), a poorly water-soluble polyphenol. NPs were prepared by the liquid-liquid dispersion method using an antisolvent water solution without or with beta-cyclodextrin (CD). NPs were spherical with a monomodal size distribution, a mean size around 140 nm and low polydispersity. Excellent colloidal stability of NPs was found at room temperature for up to 1 month. CUR entrapment was found to depend mainly on the zein/CUR ratio and related to the ability of CUR to set within hydrophobic pockets in the zein matrix. CD addition generated an increase of NP zeta potential up to +60 mV, indicating that positively charged amino acids are prompted to settle on the NP surface. Fluorescence emission spectroscopy indicated that CD interacted with lipophilic amino acids of zein altering interchain interactions and formation of glutamine bridge. Because of zein/CD interactions, mainly occurring at NP periphery, the slowing down of the CUR release rate was observed too. A combination of spectroscopic techniques unequivocally showed that zein NPs strongly interacted with mucin due to electrostatic interactions. Once sprayed on a porcine buccal mucosa, zein/CD NPs securely attached to the tissue resisting repeated washing steps but did not allow CUR transmucosal permeation. Overall, these results point at zein/CD NPs as a novel mucoadhesive platform for the buccal delivery of poorly water-soluble molecules to use as both a food supplement or a drug product to achieve local effects.

Poly(lactide- co-glycolide) Nanoparticles for Prolonged Therapeutic Efficacy of Esculentin-1a-Derived Antimicrobial Peptides against Pseudomonas aeruginosa Lung Infection: in Vitro and in Vivo Studies.

Due to their excellent in vitro activity against multidrug resistant bacteria, antimicrobial peptides (AMPs) hold promise for treatment of Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) sufferers. In this work, poly(lactide- co-glycolide) (PLGA) nanoparticles for lung delivery of AMPs deriving from the frog-skin esculentin-1a, namely, Esc(1-21) and Esc(1-21)-1c (Esc peptides), were successfully developed. Improved peptide transport through artificial CF mucus and simulated bacterial extracellular matrix was achieved in vitro. The formulations were effectively delivered through a liquid jet nebulizer already available to patients. Notably, Esc peptide-loaded nanoparticles displayed an improved efficacy in inhibiting P. aeruginosa growth in vitro and in vivo in the long term. A single intratracheal administration of Esc peptide-loaded nanoparticles in a mouse model of P. aeruginosa lung infection resulted in a 3-log reduction of pulmonary bacterial burden up to 36 h. Overall, results unravel the potential of PLGA nanoparticles as a reliable delivery system of AMPs to lungs.

In vitro/in vivo investigation on the potential of Pluronic® mixed micelles for pulmonary drug delivery.

In this paper, we shed light on the potential of Pluronic® mixed micelles in lung delivery of poorly water-soluble drugs. To this purpose, Pluronic® P123/F127 mixed micelles (PMM), exhibiting superior stability in biological fluids, were loaded with budesonide (BUD), a model hydrophobic corticosteroid, and fully investigated focusing on their stability in pulmonary-relevant media, transport through the mucus barrier and aerodynamic behaviour in vitro. Then, lung bio-distribution and efficacy were evaluated in vivo, after intra-tracheal administration in rats. PMM showed excellent stability in saline, mucin, artificial airway mucus and simulated interstitial lung fluid. Likely due to their small size coupled with the hydrophilic biofouling shell, PMM did not interact with mucin and consequently diffused through artificial mucus. BUD was loaded with high efficiency in PMM and released at sustained rate in artificial mucus. BUD-PMM dispersion in saline was efficiently delivered through a common jet nebulizer without aggregation. After intratracheal administration in rats, PMM labelled with Rhodamine B persisted in the lung up to 24 h, while serum levels rapidly dropped. Finally, the effects of BUD-PMM in a rat model of lung inflammation induced by intra-tracheal aerosolization of lipopolysaccharide (LPS) from E. coli were investigated. Of note, a single intra-tracheal aerosolization of BUD-PMM significantly reduced bronchoalveolar neutrophil infiltration and the expression of protein/enzymes derived from the arachidonic acid cascade induced by LPS, whereas a control BUD aqueous suspension showed a weaker effect. Overall, this study demonstrates that inhalable formulations of PMM can be considered as a platform for local delivery of hydrophobic drugs at lungs worth of further consideration.

Improving in vivo conversion of oleuropein into hydroxytyrosol by oral granules containing probiotic Lactobacillus plantarum 299v and an Olea europaea standardized extract.

This study reports novel food-grade granules for co-delivery of L. plantarum 299v and a standardized extract of Olea europaea leaves (Phenolea®) as oral carrier of probiotics and hydroxytyrosol. Different granule formulations containing either L. plantarum 299v (Lac), or the olive leave extract (Phe) or their combination (Lac-Phe) have been successfully produced through wet granulation employing excipients generally regarded as safe as granulating/binding agents. L. plantarum cells withstood the manufacturing process and were stable upon storage at 4 °C for more than 6 months. In vitro dissolution studies in simulated gastro-intestinal fluids showed the capability of the granules to rapidly dissolve and deliver both olive leave phenols and living L. plantarum cells. In simulated digestion conditions, Lac and Lac-Phe granules protected L. plantarum against the harsh environment of the gastro-intestinal tract. Co-administration of Lac and Phe oral granules to healthy mice provided for higher amounts of hydroxytyrosol in urines as compared to Phe granules alone, suggesting that L. plantarum 299v boosted in vivo conversion of oleuropein to hydroxytyrosol. On the other hand, PCR-assisted profiling of the Lactobacillus population in faeces obtained from mice treated with Lac or Lac plus Phe confirmed that the probiotic arrived alive to colon and was there able to exert a sort of perturbing effect on the climax colonic microflora. Overall, these results pave the way towards the development of a nutraceutical useful for combined delivery of bioactive hydroxytyrosol and probiotics to colon site.

Hybrid Lipid/Polymer Nanoparticles for Pulmonary Delivery of siRNA: Development and Fate Upon In Vitro Deposition on the Human Epithelial Airway Barrier.

BACKGROUND: Nowadays, the downregulation of genes involved in the pathogenesis of severe lung diseases through local siRNA delivery appears an interesting therapeutic approach. In this study, we propose novel hybrid lipid-polymer nanoparticles (hNPs) consisting of poly(lactic-co-glycolic) acid (PLGA) and dipalmitoyl phosphatidylcholine (DPPC) as siRNA inhalation system. METHODS: A panel of DPPC/PLGA hNPs was prepared by emulsion/solvent diffusion and fully characterized. A combination of model siRNAs against the sodium transepithelial channel (ENaC) was entrapped in optimized hNPs comprising or not poly(ethylenimine) (PEI) as third component. siRNA-loaded hNPs were characterized for encapsulation efficiency, release kinetics, aerodynamic properties, and stability in artificial mucus (AM). The fate and cytotoxicity of hNPs upon aerosolization on a triple cell co-culture model (TCCC) mimicking human epithelial airway barrier were assessed. Finally, the effect of siRNA-loaded hNPs on ENaC protein expression at 72 hours was evaluated in A549 cells. RESULTS: Optimized muco-inert hNPs encapsulating model siRNA with high efficiency were produced. The developed hNPs displayed a hydrodynamic diameter of ∼150 nm, a low polydispersity index, a negative ζ potential close to -25 mV, and a peculiar triphasic siRNA release lasting for 5 days, which slowed down in the presence of PEI. siRNA formulations showed optimal in vitro aerosol performance after delivery with a vibrating mesh nebulizer. Furthermore, small-angle X-ray scattering analyses highlighted an excellent stability upon incubation with AM, confirming the potential of hNPs for direct aerosolization on mucus-lined airways. Studies in TCCC confirmed that fluorescent hNPs are internalized inside airway epithelial cells and do not exert any cytotoxic or acute proinflammatory effect. Finally, a prolonged inhibition of ENaC protein expression was observed in A549 cells upon treatment with siRNA-loaded hNPs. CONCLUSIONS: Results demonstrate the great potential of hNPs as carriers for pulmonary delivery of siRNA, prompting toward investigation of their therapeutic effectiveness in severe lung diseases.

Poly(ethylene oxide)/hydroxypropyl-ß-cyclodextrin films for oromucosal delivery of hydrophilic drugs.

In this study, we highlight the potential of the mucoadhesive film made from a poly(ethylene oxide)/hydroxypropyl-ß-cyclodextrin (PEO/CD) mixture in the oromucosal delivery of hydrophilic drugs, with a specific focus on dexamethasone phosphate disodium salt (Dexa). CD formed a complex with Dexa in solution and did not interact with mucin as highlighted from the spectrophotometric and spectrofluorimetric analysis. Similarly, CD and PEO did not affect mucin conformation, suggesting no direct interaction between the unstirred water layer and film components. Remarkably, PEO/CD/Dexa films dissolved more slowly than those made of PEO alone also in phosphate-buffered saline (PBS) pH 6.8 and gave a time-control on Dexa delivered dose. These combined effects resulted in a higher amount of Dexa accumulated in the mucosa, which can be highly beneficial in case of local diseases. Furthermore, Dexa amount able to diffuse through porcine buccal mucosa was lower when film contained CD, highlighting how CD can act as a modulator of drug transport also in the case of water-soluble drugs. In summary, our results demonstrate the versatility of PEO/CD films in mucosal delivery of hydrophilic corticosteroids paving the way to a novel approach in the treatment of mouth diseases.

Large Porous Particles for Sustained Release of a Decoy Oligonucelotide and Poly(ethylenimine): Potential for Combined Therapy of Chronic Pseudomonas aeruginosa Lung Infections.

We have recently demonstrated that the specific inhibition of nuclear factor-κB by a decoy oligonucleotide (dec-ODN) delivered through inhalable large porous particles (LPP) made of poly(lactic-co-glycolic acid) (PLGA) may be highly beneficial for long-term treatment of lung inflammation. Nevertheless, besides chronic inflammation, multifunctional systems aimed to control also infection are required in chronic lung diseases, such as cystic fibrosis (CF). In this work, we tested the hypothesis that engineering PLGA-based LPP with branched poly(ethylenimine) (PEI) may improve LPP properties for pulmonary delivery of dec-ODN, with particular regard to the treatment of Pseudomonas aeruginosa lung infections. After getting insight into the role of PEI on the technological properties of PLGA-based LPP for delivery of dec-ODN, the putative synergistic effect of PEI free or PEI released from LPP on in vitro antimicrobial activity of tobramycin (Tb) and aztreonam (AZT) against P. aeruginosa was elucidated. Meanwhile, cytotoxicity studies on A549 cells were carried out. Results clearly demonstrate that the dry powders have promising aerosolization properties and afford a prolonged in vitro release of both dec-ODN and PEI. The encapsulation of PEI into LPP results in a 2-fold reduction of the minimum inhibitory concentration of AZT, while reducing the cytotoxic effect of PEI. Of note, the developed ODN/PLGA/PEI LPP persisted at lung at least for 14 days after intratracheal administration in rats where they can provide sustained and combined release of dec-ODN and PEI. dec-ODN will likely act as an anti-inflammatory drug, while PEI may enhance the therapeutic activity of inhaled antibiotics, which are commonly employed for the treatment of concomitant lung infections.

Overcoming barriers in Pseudomonas aeruginosa lung infections: Engineered nanoparticles for local delivery of a cationic antimicrobial peptide.

Cationic antimicrobial peptides (CAMPs) are very promising in the treatment of multi-drug resistant Pseudomonas aeruginosa lung infections experienced by cystic fibrosis (CF) patients. Nevertheless, there is an urgent need of inhalable formulations able to deliver the intact CAMP in conductive airways and to shield its interactions with airway mucus/bacterial biofilm, thus enhancing CAMP/bacteria interactions. Along these lines, the aim of this work was the design and development of nano-embedded microparticles (NEM) for sustained delivery of CAMPs in the lung. To this purpose, nanoparticles (NPs) made of poly(lactide-co-glycolide) (PLGA) containing a model CAMP, colistin (Col), were produced by emulsion/solvent diffusion technique. Engineering NPs with chitosan (CS) and poly(vinyl alcohol) (PVA) allowed to modulate surface properties and, in so doing, to improve NP transport through artificial CF mucus. In order to achieve a long-term stable dosage form useful for NP inhalation, NPs were spray-dried in different carriers (lactose or mannitol), thus producing NEM. The most promising NEM formulations were selected on the basis of bulk and flow properties, distribution of NPs in the carrier and aerosolization performance upon delivery through a breath-actuated dry powder inhaler. Of note, selected Col-loaded NEM were found to kill P. aeruginosa biofilm and to display a prolonged efficacy in biofilm eradication compared to the free Col. This effect was likely ascribable to the ability of NPs to penetrate into bacterial biofilm, as demonstrated by confocal analysis, and to sustain Col release inside it. Taken all together, our results indicate that adequate engineering of PLGA NPs represents an enticing technological approach to harness novel antimicrobials for P. aeruginosa lung infection, such as CAMPs, especially in CF.

Skin transport of PEGylated poly(ε-caprolactone) nanoparticles assisted by (2-hydroxypropyl)-ß-cyclodextrin.

The aim of this work was to investigate the potential of small nanoparticles (NPs) made of a poly(ethylene glycol)-poly(ε-caprolactone)-amphiphilic diblock copolymer (PEG-b-PCL, PEG=2kDa and PCL=4.2kDa) as drug carrier system through the skin. Zinc(II) phthalocyanine (ZnPc), selected as lipophilic and fluorescent model molecule, was loaded inside NPs by a melting/sonication procedure. Loaded NPs with a hydrodynamic diameter around 60nm, a slightly negative zeta potential and a ZnPc entrapment dependent on polymer/ZnPc ratio were obtained. Spectroscopic investigations evidenced that ZnPc was entrapped in monomeric form maintaining its emission properties. The transport of ZnPc through porcine ear skin was evaluated on Franz-type diffusion cells after treatment with different vehicles (water or PEG 0.4kDa) containing free ZnPc or ZnPc-loaded NPs without and with (2-hydroxypropyl)-ß-cyclodextrin (HPßCD) as permeation enhancer. Independently of the sample tested, ZnPc was transported in the skin without reaching receptor compartment. On the other hand, ZnPc was found in the skin in large amount and also in the viable epidermis when delivered through NPs associated with HPßCD, especially in conditions limiting water evaporation. Fluorescence images of skin samples after 24h of permeation were in line with ZnPc dosage in the skin and demonstrated the ability of NPs covalently tagged with rhodamine to penetrate the skin and to locate in the intercellular spaces. Insight into skin chemical properties upon application of NPs by confocal Raman spectroscopy demonstrated that HPßCD caused an alteration of water profile in the skin, highly reducing the degree of hydration at stratum corneum/viable epidermis interface which can promote NP transport. Taken together, these results highlight PEG-b-PCL NPs coupled with HPßCD as a novel vehicle for the skin delivery of highly lipophilic compounds paving the way to several applications.