Targeted delivery of rifaximin using P6.2-decorated bifunctional PLGA nanoparticles for combating Staphylococcus aureus infections

The emergence of antibiotic resistance makes the treatment of bacterial infections difficult and necessitates the development of alternative strategies. Targeted drug delivery systems are attracting great interest in overcoming the limitations of traditional antibiotics. Here, we aimed for targeted delivery of rifaximin (RFX) by decorating RFX-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) with synthetic P6.2 peptide, which was used as a targeting agent for the first time. Our results showed that encapsulation of RFX into NPs increased its antibacterial activity by improving its solubility and providing controlled release, while P6.2 modification allowed targeting of NPs to S. aureus bacterial cells. A promising therapeutic approach for bacterial infections, these P6.2-conjugated RFX-loaded PLGA NPs (TR-NP) demonstrated potent antibacterial activity against both strains of S. aureus. The antibacterial activity of RFX-loaded PLGA NPs (R-NP) showed significant results with an increase of 8 and 16-fold compared to free RFX against S. aureus and MRSA, respectively. Moreover, the activity of targeted nanoparticles was found to be increased 32 or 16-fold with an MBC value of 0.0078 μg/mL. All nanoparticles were found to be biocompatible at doses where they showed antimicrobial activity. Finally, it revealed that P6.2-conjugated targeted nanoparticles extremely accumulated in S. aureus rather than E. coli.

Microfluidic-assisted preparation of PLGA nanoparticles loaded with insulin: a comparison with double emulsion solvent evaporation method

Poly lactic-co-glycolic acid (PLGA) is an ideal polymer for the delivery of small and macromolecule drugs. Conventional preparation methods of PLGA nanoparticles (NPs) result in poor control over NPs properties. In this research, a microfluidic mixer was designed to produce insulin-loaded PLGA NPs with tuned properties. Importantly; aggregation of the NPs through the mixer was diminished due to the coaxial mixing of the precursors. The micromixer allowed for the production of NPs with small size and narrow size distribution compared to the double emulsion solvent evaporation (DESE) method. Furthermore, encapsulation efficiency and loading capacity indicated a significant increase in optimized NPs produced through the microfluidic method in comparison to DESE method. NPs prepared by the microfluidic method were able to achieve a more reduction of trans-epithelial electrical resistance values in the Caco-2 cells compared to those developed by the DESE technique that leads to greater paracellular permeation. Compatibility and interaction between components were evaluated by differential scanning calorimetry and fourier transform infrared analysis. Also, the effect of NPs on cell toxicity was investigated using MTT test. Numerical simulations were conducted to analyze the effect of mixing patterns on the properties of the NPs. It was revealed that by decreasing flow rate ratio, i.e. flow rate of the organic phase to the flow rate of the aqueous phase, mixing of the two streams increases. As an alternative to the DESE method, high flexibility in modulating hydrodynamic conditions of the microfluidic mixer allowed for nanoassembly of NPs with superior insulin encapsulation at smaller particle sizes.

Quality by Design as a Tool in the Optimisation of Nanoparticle Preparation-A Case Study of PLGA Nanoparticles

Nanoparticles can be used as drug carriers in various applications (e.g., in pulmonary drug delivery and mucosal vaccination). For further investigations, such as drug release studies, as well as for cell and tissue targeting, particles with defined properties are needed. The purpose of the study was to show a multi-step systematic method utilising quality by design to ensure the quality of ovalbumin loaded polylactic-co-glycolic acid nanoparticles (OVA-PLGA-NP), which can be delivered to the lung, and to gain knowledge of the preparation method (double-emulsion solvent evaporation method) in an early development process. Within a definitive screening design, several process parameters (OVA, PLGA and stabiliser concentrations, stirring time and stirring speed of inner emulsion and stirring time and stirring speed of double emulsion) were varied to analyse their impact on resulting properties (z-average, PDI, loading efficiency and loading capacity). The results showed that the preparation of the inner emulsion mainly influenced the drug loading, while the parameters of the second emulsifying step controlled the size. Then a central composite response surface design was used to achieve a predictable OVA-PLGA-NP with an average particle size of 700 nm and high drug-loading. This also enabled the demonstration of curvature and interaction of the stabiliser and the PLGA concentration.

Bevacizumab encapsulation into PLGA nanoparticles functionalized with immunouteroglobin-1 as an innovative delivery system for atherosclerosis

Atherosclerosis represents one of the main causes of death in the Western world. It is a multifactorial pathology characterized by lesions that reduce the lumen of the vessels causing serious clinical events. The extradomain-B of fibronectin is overexpressed during angiogenesis and in tissues undergoing growth and extensive remodeling, i.e., atherosclerotic plaque. Bevacizumab is a recombinant humanized monoclonal antibody that can play a role against the angiogenesis process reducing the risk associated with this process in atherosclerosis. In this work, an innovative drug delivery device for target delivery of bevacizumab to the atherosclerotic lesion is proposed. A production protocol for poly(lactic-co-glycolic acid)-polyethylene glycol nanoparticles loaded with bevacizumab and functionalized with immunouteroglobin-1 was designed. Once immunouteroglobin-functionalized nanoparticles were produced, they were characterized regarding morphology, mean diameter, ζ-potential, association and conjugation efficiencies, bevacizumab release profile both in phosphate buffered saline and in serum, bevacizumab stability after release, cytocompatibility, and hemocompatibility. Nanoparticle mean diameter was in the range of 217-265 nm, their surface charge was between -21 and - 8 mV, and the association and conjugation efficiency of about 76 and 59 %, respectively. Fourier transform infrared spectroscopy analysis confirmed the functionalization of their surface with immunouteroglobin-1. In vitro assays showed that the studied nanoparticles were cytocompatible, once in contact with human endothelial and murine macrophages cell line up to 72 h, and hemocompatible, once in contact with red blood cells, at different concentrations of encapsulated BEV (0.1, 1, 10, and 100 μg_BEV/mL).

Comparative study of cilnidipine loaded PLGA nanoparticles: process optimization by DoE, physico-chemical characterization and in vivo evaluation

Cilnidipine (CND) is known to have low oral bioavailability due to its poor aqueous solubility, low dissolution rate, and high gut wall metabolism. In the present study, CND-loaded PLGA nanoparticles (CND-PLGA-NPs) were prepared with two different grades of PLGA (50:50 and 75:25) by design of experiment. Critical factors affecting particle size and entrapment efficiency (EE%) were assessed by mixed design approach, comprising of Plackett-Burman design followed by rotatable central composite design. Particle size, PDI, zeta potential, and EE% of optimized formulations of CND-PLGA(50:50)-NPs and CND-PLGA(75:25)-NPs were 211.6 ± 1.8 nm, 0.21 ± 0.05, - 15.1 ± 1.6 mV, and 85.9 ± 1.5% and 243.5 ± 2.4 nm, 0.23 ± 0.06, -19.6 ± 1.3 mV, and 92.0 ± 1.2% respectively. No significant changes were observed in physical stability of NPs when stored at 25 °C/60% RH over a period of 3 months. Pharmacokinetic studies revealed that F_abs of CND-PLGA(50:50)-NPs (1.15) and CND-PLGA(75:25)-NPs (2.23) were significantly higher than the free CND (0.26). The C_max and AUC_0-∞ of CND-PLGA(50:50)-NPs (787.42 ± 27.38 ng/mL and 9339.37 ± 252.38 ng/ml × h) and CND-PLGA(75:25)-NPs (803.49 ± 19.63 ng/mL and 18,153.34 ± 543.05 ng/ml × h) were significantly higher (p ˂ 0.0001) compared with free CND (367.69 ± 47.22 ng/mL and 2107.95 ± 136.40 ng/ml × h). MRT_Oral of CND-PLGA(50:50)-NPs (33.36 ± 0.48 h) and CND-PLGA(75:25)-NPs (48.37 ± 0.61 h) were significantly higher (p ˂ 0.0001) compared with free CND (4.69 ± 0.58 h). CND-PLGA-NPs can provide higher and sustained plasma drug levels of CND and be effective in antihypertensive therapy. Graphical abstract.

Effects of Compositional Tailoring on Drug Delivery Behaviours of Silica Xerogel/Polymer Core-shell Composite Nanoparticles

Conventional core-shell polymer nanoparticles usually exhibit a rapid release rate with their release kinetics mainly adjusted through changing composition of the polymer shells, limiting their applications for prolonged drug delivery. As a solution to these problems, silica xerogel/polymer core-shell-structured composite nanoparticles have been proposed. Different with our previous work centring on studying process variables, we here focused on investigating the effects of key compositional variables on essential properties of the composite nanoparticles. The drug release profiles (in vitro) were well interpreted by the Baker and Lonsdale model on a predicted two-stage basis. The first stage (<1 day) was well controlled from 18.6% to 45.9%; the second stage (1-14 days) was tailored in a range from 28.7 to 58.2% by changing the composition of the silica xerogel cores and polymeric shells. A substantial achievement was reducing the release rate by more than 40 times compared with that of conventional polymer nanoparticles by virtue of the silica xerogel cores. A semi-empirical model was also established in the first attempt to describe the effects of polymer concentration and drug loading capacity on the size of the composite nanoparticles. All these results indicated that the composite nanoparticles are promising candidates for prolonged drug delivery applications.

Investigations of octylglyceryl dextran-graft-poly(lactic acid) nanoparticles for peptide delivery to the brain

Aim: Develop modified dextran nanoparticles showing potential to assist with drug permeation across the blood–brain barrier for the delivery of neuropeptides. Methods: Nanoparticles loaded by emulsification with model macromolecular actives were characterized in terms of stability, cytotoxicity and drug-release behavior. Peptide-loaded nanoformulations were tested in an in vivo trout model and in food-deprived mice. Results: Nanoformulations loaded with model peptides showed good stability and appeared nontoxic in low concentration against human brain endothelial cells. They were found to preserve the bioactivity of loaded peptides (angiotensin II) as demonstrated in vivo using a trout model, and to induce a transient reduction of food consumption in mice when loaded with an anorexigenic octaneuropeptide. Conclusion: Octylglyceryl dextran-graft-poly(lactic acid) nanoparticles formulated by emulsification demonstrate potential for peptide delivery.

Preparation and characterization of biodegradable polyhydroxybutyrate-co-hydroxyvalerate/polyethylene glycol-based microspheres

The in vivo effectiveness of biomolecules may be limited by their rapid diffusion in the body and short half-life time. Encapsulation of these biomolecules allows protecting them against degradation and ensuring a controlled release over time. In this work, the production of polyhydroxybutyrate-co-hydroxyvalerate/polyethylene glycol-based microspheres loaded with heparin by double emulsion-solvent evaporation is investigated. Significant improvements are achieved after blending PHB-HV microspheres with PEG. First of all, an important decrease of the initial burst effect is ensured. Moreover, lower degradation of the microspheres is observed after 30days in the release medium. Finally, the release rate could be controlled using different PEG molecular weights and concentrations. A toxic effect of PHB-HV 30% PEG 1100gmol^-1 microspheres is observed whereas PHB-HV and PHB-HV 30% PEG 10,000gmol^-1 microspheres are not toxic. These microspheres seem to be most suited for further tissue engineering applications. The effectiveness of direct PEG blending to PHB-HV is proved, limiting the use of chemical reagents for PHB-HV/PEG copolymer synthesis and steps for chemical reagents removal from the copolymer.