Solvent impact on polymer nanoparticles prepared nanoprecipitation

Bioinspired zwitterionic triblock copolymers designed for colloidal drug delivery: 2 - Biological evaluation

In this work, poly(lactide) nanoparticles were equipped with a bioinspired coating layer based on poly[2-(methacryloyloxy)ethyl phosphorylcholine] and then evaluated when administered to the lungs and after intravenous injection. Compared to the plain counterparts, the chosen zwitterionic polymer shell prevented the coated colloidal formulation from aggregation and conditioned it for lower cytotoxicity, protein adsorption, complement activation and phagocytic cell uptake. Consequently, no interference with the biophysical function of the lung surfactant system could be detected accompanied by negligible protein and cell influx into the bronchoalveolar space after intratracheal administration. When injected into the central compartment, the coated formulation showed a prolonged circulation half-life and a delayed biodistribution to the liver. Taken together, colloidal drug delivery vehicles would clearly benefit from the investigated poly[2-(methacryloyloxy)ethyl phosphorylcholine]-based polymer coatings.

Bioinspired zwitterionic triblock copolymers designed for colloidal drug delivery: 1 - Synthesis and characterization

This study describes the synthesis and characterization of triblock copolymers composed of poly[2-(methacryloyloxy)ethyl phosphorylcholine]-block-poly(propylene glycol)-block-poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC-b-PPG-b-PMPC) intended for, but not limited to, applications in colloidal drug delivery. Atom transfer radical polymerization led to a library of well-defined PMPC-b-PPG-b-PMPC triblock copolymers with varying overall molecular weight (ranging from ∼5 to ∼25 kDa) and composition (weight fraction of the hydrophobic PPG block ranged from ∼10 to ∼50 wt%). The properties of the synthesized triblock copolymers were linked to the PPG to bioinspired PMPC block(s) ratio, where the more hydrophilic species showed adequate aqueous solubility, surface activity and biocompatibility (non-toxicity) in in vitro cell culture. Their amphiphilic nature makes them adsorb efficiently onto polymer nanoparticles, what improves colloidal stability under stress conditions and, furthermore, depletes proteins from unwanted adsorption to the underlying surface. The current findings strengthen our insights into structure-function relationships of PMPC-based coatings leading to protecting shells on relevant polymer nanoparticle formulations. PMPC-b-PPG-b-PMPC triblock copolymers composed of a hydrophobic PPG block of 2-4 kDa flanked by two hydrophilic PMPC blocks each of 5-10 kDa seem to be most promising to enhance colloidal drug delivery vehicles.

Preparation and Characterization of Polymeric Microparticles Based on Poly(ethylene brassylate-co-squaric Acid) Loaded with Norfloxacin

In recent years, increasing interest has been accorded to polyester-based polymer microstructures, driven by their promising potential as advanced drug delivery systems. This study presents the preparation and characterization of new polymeric microparticles based on poly(ethylene brassylate-co-squaric acid) loaded with norfloxacin, a broad-spectrum antibiotic. Polymacrolactone was synthesised in mild conditions through the emulsion polymerization of bio-based and renewable monomers, ethylene brassylate, and squaric acid. The microparticles were obtained using the precipitation technique and subsequently subjected to comprehensive characterization. The impact of the copolymer/drug ratio on various properties of the new system was systematically evaluated, confirming the structure of the copolymer and the encapsulation of norfloxacin. The microspheres are approximately spherical and predominantly homogeneously distributed. The average hydrodynamic diameter of the microparticles falls between 400 and 2000 nm, a decrease that is observed with the increase in norfloxacin content. All samples showed good encapsulation efficiency and drug loading capacity, with the highest values obtained for microparticles synthesised using an equal ratio of copolymer and drug. In vitro drug release results disclose that norfloxacin molecules are released in a sustained biphasic manner for up to 24 h. Antimicrobial activity was also studied, with samples showing very good activity against E. coli and moderate activity against S. aureus and E. faecalis. In addition, HDFA human fibroblast cell cultures demonstrated the cytocompatibility of the microparticles.

Coalescence of immiscible droplets in liquid environments

HYPOTHESIS

Droplet coalescence process is important in many applications and has been studied extensively when two droplets are surrounded by gas. However, the coalescence dynamics would be different when the two droplets are surrounded by an external viscous liquid. The coalescence of immiscible droplets in liquids has not been explored.

EXPERIMENTS

In the present research, the coalescence of two immiscible droplets in low- and high-viscosity liquids is investigated and compared with their miscible counterparts experimentally. The coalescence dynamics is investigated via high-speed imaging, and theoretical models are proposed to analyze the growth of the liquid bridge.

FINDINGS

We find that, the liquid bridge r evolves differently due to the constraint from the triple line in the bridge region, which follows r∝t2/3 for low-viscosity surroundings. While for high-viscosity surroundings, the liquid bridge grows at a constant velocity ur which varies with the surrounding viscosity μs as [Formula: see text] . In the later stage of the bridge growth, the bridge evolution again merges with the well-established power-law regime r∝t1/2, being either in low or high-viscosity liquids. Moreover, a new inertia-viscous-capillary timescale is proposed, which unifies the combined influence of inertia, viscous, and capillary forces on the evolution of the liquid bridge in liquid environments, highlighting the joint role of inertia and viscous resistance in the coalescence process.

Glycerol- and diglycerol-based polyesters: Evaluation of backbone alterations upon nano-formulation performance

Despite the success of polyethylene glycol-based (PEGylated) polyesters in the drug delivery and biomedical fields, concerns have arisen regarding PEG's immunogenicity and limited biodegradability. In addition, inherent limitations, including limited chemical handles as well as highly hydrophobic nature, can restrict their effectiveness in physiological conditions of the polyester counterpart. To address these matters, an increasing amount of research has been focused towards identifying alternatives to PEG. One promising strategy involves the use of bio-derived polyols, such as glycerol. In particular, glycerol is a hydrophilic, non-toxic, untapped waste resource and as other polyols, can be incorporated into polyesters via enzymatic catalysis routes. In the present study, a systematic screening is conducted focusing on the incorporation of 1,6-hexanediol (Hex) (hydrophobic diol) into both poly(glycerol adipate) (PGA) and poly(diglycerol adipate) (PDGA) at different (di)glycerol:hex ratios (30:70; 50:50 and 70:30 mol/mol) and its effect on purification upon NPs formation. By varying the amphiphilicity of the backbone, we demonstrated that minor adjustments influence the NPs formation, NPs stability, drug encapsulation, and degradation of these polymers, despite the high chemical similarity. Moreover, the best performing materials have shown good biocompatibility in both in vitro and in vivo (whole organism) tests. As preliminary result, the sample containing diglycerol and Hex in a 70:30 ratio, named as PDGA-Hex 30%, has shown to be the most promising candidate in this small library analysed. It demonstrated comparable stability to the glycerol-based samples in various media but exhibited superior encapsulation efficiency of a model hydrophobic dye. This in-depth investigation provides new insights into the design and modification of biodegradable (di)glycerol-based polyesters, potentially paving the way for more effective and sustainable PEG-free drug delivery nano-systems in the pharmaceutical and biomedical fields.

Novel green-based polyglycerol polymeric nanoparticles loaded with ferulic acid: A promising approach for hepatoprotection

In the pursuit of eco-friendly and sustainable materials, polyglycerol diacid polymers hold immense promise for drug delivery compared to those derived from fossil fuels. Harnessing this potential, we aimed to prepare nanoparticles (NPs) derived from sustainable polymers, loaded with ferulic acid (FA), a natural polyphenolic compound known for its shielding effect against liver-damaging agents, including carbon tetrachloride (CCl4). Glycerol was esterified with renewable monomers, such as succinic acid, adipic acid, and/or FA, resulting in the creation of a novel class of polyglycerol diacid polymers. Characterization via Fourier-transform infrared spectroscopy and nuclear magnetic resonance confirmed the successful synthesis of these polymers with <7 % residual monomers. FA-loaded NPs were fabricated using the newly synthesized polymers. To further augment their potential, the NPs were coated with chitosan. The chitosan-coated NPs boasted an optimal PS of 290 ± 5.03 nm, showing superior physical stability, and a commendable EE% of 58.79 ± 0.43%w/v. The cytotoxicity was examined on fibroblast cells using the SRB assay. In-vivo experiments employing a CCl4-induced liver injury model yielded compelling evidence of the heightened hepatoprotective effects conferred by chitosan-coated particles. This demonstrates the benefits of incorporating sustainable polymers into innovative composites for efficient drug delivery, indicating their potential for creating versatile platforms for various therapeutic applications.

In silico and in vitro assessment of an optimized QbD-guided myoinositol and metformin-loaded mucus-penetrating particle-based gel for the amelioration of PCOS

Polycystic ovarian syndrome (PCOS) is a multi-factorial endocrine disorder affecting women of reproductive age. However, its high prevalence and the unsuccessful translation of conventional modalities have made PCOS a pharmaco-therapeutic challenge. In the present study, we explored bi-formulations (comprising metformin-loaded mucus-penetrating nanoparticles, MTF-MPPs, and myoinositol-loaded mucus-penetrating particles, MI-MPPs) incorporated in a carbomer gel tailored for intravaginal administration. For the development and optimization of the MPPs-gel, a QbD (quality by design) approach was employed, including the initial and final risk assessment, central composite design of experts, and method validation. The optimized MTF-MPPs and MI-MPPs possessed an optimum nanometric particle size (195.0 nm and 178.8 nm, respectively) and a PDI of 0.150 and 0.123, respectively, together with a negligible negative zeta potential (-5.19 mV and -6.19 mV, respectively) through the vaginal mucus. It was observed that the MPPs are small and monodisperse with a neutral surface charge. It was observed that the MPPs-gel formulations released approximately 69.86 ± 4.65% of MTF and 67.14 ± 5.74% of MI within 120 h (5 days), which was observed to be sustained unlike MFT-MI-gel with approximately 94.89 ± 4.17% of MTF and 90.91 ± 15% of MI drugs released within 12 h. The confocal microscopy study of rhodamine-loaded MPPs indicated that they possessed a high fluorescence intensity at a depth of 15 μm, while as the penetration trajectory in the vaginal tissue increased to 35 μm, their intensity was reduced, appearing to be more prominent in the blood vessels. The analyzed data of MPPs-gel suggest that the optimized MPPs-gel formulation has potential to reach the targeted area via the uterovaginal mucosa, which has a wide network of blood vessels. Subsequently, in vivo studies were conducted and the results revealed that the proposed MPPs-gel formulation could regulate the estrous cycle of the reproductive system compared to the conventional formulation. Moreover, the formulation significantly reduced the weight of the ovaries compared to the control and conventional vaginal gel. Biochemical estimation showed improved insulin and sex hormone levels. Thus, the obtained data revealed that the deep penetration and deposition of MTF and MI on the targeted area through intravaginal delivery resulted in better therapeutic effects than the conventional vaginal gel. The obtained results confirmed the amelioration of PCOS upon treatment using the prepared MPPs-gel formulation. According to the relevant evaluation studies, it was concluded that MPPs-gel was retained in the vaginal cavity for systemic effects. Also, the sustained and non-irritating therapeutic effect meets the safety aspects. This work serves as a promising strategy for intravaginal drug delivery.