Amphiphilic Graft Copolymers Research Articles

Tailored Supersaturable Immediate Release Behaviors of Hypotensive Supersaturating Drug-Delivery Systems Combined with Hot-Melt Extrusion Technique and Self-Micellizing Polymer.

The short-term immediate release of supersaturated drug-delivery systems (SDDSs) presents an interesting process that can be tailored to multi-stage release events including initial release after dosing and dissolution, evolved release over longer dissolution periods for biological absorption, and terminal release following the end of immediate release. However, although comprehensive analysis of these critical release behaviors is often ignored yet essential for understanding the supersaturable immediate-release events for supersaturable solid formations when employing new techniques or polymers matched to a particular API. Hot-melt extrusion (HME) has become a popular continuous thermodynamic disordering technique for amorphization. The self-micellizing polymer Soluplus® is reported to be a potential amorphous and amphiphilic graft copolymer frequently used in many nano/micro supersaturable formulations. Our current work aims to develop hypotensive supersaturating solid dispersion systems (faSDDSHME) containing the BCS II drug, felodipine, when coordinately employing the HME technique and self-micellizing Soluplus®, and to characterize their amorphization as well as immediate release. Other discontinuous techniques were used to prepare control groups (faSDDSSE and faSDDSQC). Tailored initial/evolved/terminal three-stage supersaturable immediate-release behaviors were identified and possible mechanisms controlling the release were explored. HME produced the highest initial release in related faSDDSHME. During the evolved-release period, highly extended "spring-parachute" process was found in HME-induced amorphization owing to its superior supersaturation duration. Due to the enhanced crystallization inhibition effect, faSDDSHME displayed the strongest terminal release as measured by solubility. For release mechanisms associated with HME, molecular interaction is not the likely dominant mechanism responsible for the improved properties induced by faSDDSHME. For release mechanisms involved with the polymer Soluplus® itself, they were found to inhibit drug recrystallization, spontaneously solubilize the drug and lead to improved molecular interactions in all SDDS systems, which were the factors responsible for the improved release. These mechanisms play an important role for the generation of an extended multi-stage immediate release produced via HME or self-micellizing polymer. This study provides a deeper understanding on amorphization and superior multi-stage supersaturable immediate-release behaviors for a particular hypotensive supersaturated delivery system combined with an HME-based continuous manufacturing technique and self-micellizing polymer strategy.

Microphase-separated morphology controlled polyimide graft copolymer membranes for CO2 separation

We report microphase-separated structured, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)–2,4,6-trimethyl-1,3-diaminobenzene (DAM) polyimide (PI)-based PI-POEM graft copolymer membranes with various poly(ethylene glycol)methyl ether methacrylate (POEM) grafting ratios for efficient CO2 separation. The brominated PI (PI-Br) was used as a macroinitiator to form amphiphilic microphase-separated PI-POEM graft copolymers via atom transfer radical polymerization (ATRP). The proton nuclear magnetic resonance (1H NMR) spectra demonstrate the chemical structure of PI-POEM graft copolymers with controllable POEM concentrations. The PI-POEM graft copolymers exhibit modified mechanical properties with a higher elongation at break and more hydrophilic membrane surface properties because of the relatively rubbery and hydrophilic POEM side chain addition. Notably, the PI-POEM graft copolymers exhibit microphase-separated morphology-controllable characteristics based on transmission electron microscope (TEM) images and X-ray scattering (small- and wide-angle) spectra. These structural properties enable the PI-POEM graft copolymer membranes to develop carbon dioxide (CO2)-gas-favorable transport characteristics with a high CO2 affinity. The PI-POEM graft copolymer membranes can exhibit controllable separation performance depending on the POEM concentrations. Consequently, the PI-POEM(3:1) graft copolymer membrane improves simultaneously in permeability and selectivity compared with the pure PI membrane. Thus, the PI-POEM(3:1) graft copolymer membrane exhibits CO2 permeability of 1,220 Barrer with selectivities of 27.5 and 23.5 for CO2/CH4 and CO2/N2, and H2 permeability of 810 Barrer with selectivities of 16.2 and 15 for H2/CH4 and H2/N2.

Self-Organization of Graft Copolymers and Retortable iPP-Based Nanoporous Films Thereof

Polyolefins might become inexpensive alternatives to the existing membranes based on polyethersulfone. Here, we disclose the production of retortable, well-defined polypropylene (PP)-based nanoporous films derived from amphiphilic graft copolymer precursors. The graft copolymers, containing a polypropylene backbone and polyester grafts, were obtained by grafting lactones, specifically δ-valerolactone and ε-caprolactone, from well-defined randomly functionalized poly(propylene-co-10-undecen-1-ol) as a macroinitiator. Depending on the composition, the graft copolymers self-assemble into droplet, cylindrical, lamellar, or interconnected two-phase morphologies. Functional mesoporous iPP-based films were fabricated by the selective degradation of the polyester blocks of the copolymers. Their structure and morphology were studied using atomic force microscopy (AFM), scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and solid-state NMR, while the mesoporosity was assessed by nitrogen sorption experiments. The pore size of the films is strongly influenced not only by the volume fraction of the copolymer blocks but unexpectedly also by the topology (i.e., number of grafts) of the graft copolymer, as was confirmed by computational modeling studies using the dynamic density functional theory (DDFT) engine within the Culgi software. This work provides a conclusive answer on how the morphology of iPP-based graft copolymers is tuned by the copolymer composition and the amount and length of the grafted polyester blocks. Filtration tests and flux determination demonstrated that such structurally well-defined mesoporous products could be considered for the development of ultrafiltration membranes while the chemical resistance and sterilization tests revealed their robust performance and suitability for water purification applications.

Synthesis and application of nonionic graft copolymers P(mPEG-g-MMA)

The goal of this research is to prepare novel amphiphilic graft copolymers (nonionic) based on hydrophilic poly (ethylene glycol) methyl ether (mPEG) and hydrophobic methyl methacrylate (MMA) at room temperature and pressure. To generate P(mPEG-g-MMA) grafts, poly (ethylene glycol) methyl ether (mPEG) was synthesized and grafted with varied ratios of methyl methacrylate (MMA) in the existence of benzoyl peroxide as an initiator utilizing a macro-free radical initiator procedure under the effect of heating in toluene. The research discussed in this paper looked at the possibility of using the synthesized graft copolymer P(mPEG-g-MMA) as a nonionic demulsifier in Petroleum Crude Oil Emulsions. The produced nonionic surfactants were assessed as water demulsifiers in oil emulsions that were noticeable at varying oil: water ratios at 60oC. According to the demulsifier chemical compositions as well as concentrations, the testing findings revealed that the dehydration rate of the prepared demulsifiers reached 100%. The optimal demulsifier dose was 300 ppm.

Thermo-responsive graft copolymer PSf-g-PNIPM: Reducing the structure parameter via morphology control of forward osmosis membrane substrates

An amphiphilic graft copolymer, consisting of a polysulfone (PSf) main chain and poly(n-isopropylacrylamide) (PNIPM) grafts, was synthesized via a combination of atom transfer radical polymerization and click chemistry. The copolymer's structure characteristics (PNIPM length and content) substantially impacts membrane morphology and performance, and were optimized firstly. The resulting copolymer PSf-g-PNIPM with the best characteristics was used as an additive in the fabrication of PSf porous substrates by phase inversion. The effect of the graft copolymer on the physicochemical characteristics and performance of PSf substrate was thoroughly studied. The pure water permeability displays a temperature dependency for PSf substrates with 20 wt% PSf-g-PNIPM, with the maximum above the LCST of the PNIPM side chains. Thin film composite membranes formed on these substrates via interfacial polymerization show a significantly improved water flux during forward osmosis operation. The morphology and performance of the PSf-g-PNIPM modified substrate can be further tuned by the casting medium temperature. Membranes formed below the LCST show higher porosity and water flux.

Trials and adventures of the synthesis and evaluation of amphiphilic graft copolymers with dynamic topology

AbstractAmphiphilic graft copolymers were prepared via a grafting through approach to yield materials with a hydrophilic backbone and hydrophobic arms. The thermally responsive macromonomers were designed to contain a Diels–Alder adduct such that cyclo‐reversion would cleave the arms from the backbone thus altering polymer topology, composition and solubility. The macromonomers were prepared via light‐inducted atom transfer radical polymerization followed by post‐polymerization modification to install a polymerizable functionality. Next, free radical polymerization was employed to yield thermally responsive amphiphilic graft copolymers, whose solution state characteristics were extensively characterized by UV/Vis spectroscopy and fluorimetry. Due to the amphiphilic nature of the graft copolymer, some unexpected results occurred because of aggregation and solubility limitations. Furthermore, it was discovered that poly(N‐isopropyl acrylamide) exhibited distinct and unique aggregation properties by itself.

Potential of Functionalized Polyolefins in a Sustainable Polymer Economy: Synthetic Strategies and Applications.

Polymers play a crucial role in our modern life as no other material exists that is so versatile, moldable, and lightweight. Consequently, the demand for polymers will continue to grow with the human population, modernization, and technological developments. However, depleted fossil resources, increasing plastic waste production, ocean pollution, and related growing emission of greenhouse gases has led to a change in the way we think about the use of polymers. Although polymers were never designed to be recycled, it is clear that a linear polymers economy is no longer sustainable. The design for recycling and reuse and life-cycle analyses will become increasingly important factors when deciding on which polymer to choose for a certain application. Of all polymers, polyolefins have the lowest life-cycle environmental impact and even outperform renewable polymers. However, polyolefins are chemically inert and reveal a low surface energy. Combining their excellent mechanical properties with the ability to adhere to other materials or create self-assembled or nanostructured materials would widen the application window of polyolefins even more.This Account covers part of our personal account in the field of functionalized polyolefin synthesis and their application development. We start with addressing the challenge of finding suitable catalysts that tolerate nucleophilic functionalities, which tends to poison most electrophilic catalysts even when passivated with, for example, an aluminum alkyl. We argued that lowering of the oxidation state of a titanium-based catalyst might lower the electrophilicity of the metal center. Indeed, this simple approach resulted in an unprecedentedly high tolerance toward aluminum alkyl-passivated alkenols during their copolymerization with ethylene. Interestingly, catalyst deactivation was much less pronounced during the copolymerization of propylene and aluminum-passivated alkenols, clearly demonstrating the protective effect of the methyl branch in the growing polymer. Because the use of randomly functionalized polypropylenes is rather underdeveloped, as compared to the corresponding randomly functionalized polyethylenes, we focused on potential applications of the former material. Atactic or low-crystalline hydroxyl- and carboxylic acid-functionalized propylene-based co- and terpolymers form elastomers with interesting properties that can be influenced by enhancing the hydrogen bonding within the system or by creating ionomers. The polar functionalities cluster together in domains that can host small polar molecules such as, for example, a pH indicator, thus affording useful sensors. The functionalized polyolefins can also be used as precursors for amphiphilic graft copolymers, undergoing self-assembly and therefore being suitable for nanoporous membrane preparation. The graft copolymers also proved to be effective compatibilizers in various polymer blends.

Amphiphilic Graft Copolymer of Polylysine-g-polytetrahydrofuran and Its Biological Properties

Amphiphilic Graft Copolymer of Polylysine-<i>g</i>-polytetrahydrofuran and Its Biological Properties

Comb like amphiphilic graft copolymers bearing PDMS and PEO side chains: synthesis and solvent assisted self-assembly behavior

Comb like amphiphilic graft copolymers bearing PDMS and PEO side chains: synthesis and solvent assisted self-assembly behavior

Soluplus® polymeric nanomicelles improve solubility of BCS-class II drugs

The issue of poor aqueous solubility is often a great hitch in the development of liquid dosage forms for those drugs that the Biopharmaceutics Classification System (BCS) includes in classes II and IV. Among the possible technological solutions, inclusion of the drug molecule within polymeric micelles, and particularly nanomicelles, has been proposed in the last years as a valid strategy. Our attention has been recently attracted by Soluplus®, an amphiphilic polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer able to form small and stable nanomicelles. The aim of this study was to characterize Soluplus® nanomicelles to enhance the apparent solubility of three model APIs, categorized in BCS class II: ibuprofen (IBU), idebenone (IDE), and miconazole (MIC). Drug-loaded Soluplus® micelles with a mean size around 60–70 nm were prepared by two methods (direct dissolution or film hydration method). The prepared nanosystems were characterized in terms of mean particle size and Zeta potential, physical stability, drug solubility, and in vitro drug release. The solubility of the tested APIs was shown to increase linearly with the concentration of graft copolymer. Soluplus® can be easily submitted to membrane filtration (0.2 µm PES or PTFE membranes), showing the potential to be sterilized by this method. Freeze-drying enabled to obtain powder materials that, upon reconstitution with water, maintained the initial micelle size. Finally, viscosity studies indicated that these nanomicelles have potential applications where a bioadhesive material is advantageous, such as in topical ocular administration.Graphical abstract

Highlights on polymeric micelles as versatile nanocarriers for drug transporting

Polymeric micelles are nanoscale core-shell structures formed by amphiphilic (block or graft) copolymers, that can self-aggregate in an aqueous medium. PMs characterized by small size, spherical shape, lower critical micellar concentration, which gave higher&#x0D; stability for PMs over conventional surfactant micelles. The core/shell structure permits polymeric micelle to entrap poor soluble drugs and can improve their solubility and permeability. The preparation of PMs tends to be relatively easy as compared to other novel drug delivery systems. This review focus on the general properties, types, types of copolymer utilized, formation mechanism, preparation methods, characterization techniques, and the applications on PMs.

Biocompatible propylene glycol alginate-g-polytetrahydrofuran amphiphilic graft copolymers for highly effective drug carriers

The acylated propylene glycol alginate-g-polytetrahydrofuran amphiphilic graft copolymers (APGA-g-PTHF) with various grafting numbers (GN) of 3–23 per 1000 monosaccharide rings and PTHF (PTMG or PTMO) branches with different molecular weights (Mn,PTHF) of 600–3400 g/mol could be successfully synthesized via nucleophilic substitution of PTHF living chains carrying oxonium ions with the –OH side groups of APGA backbone. The nanophase separation, the hydrophobicity and the surface roughness were increased due to the less restricted movement of hydrophobic PTHF branches to the surface. APGA-g-PTHF graft copolymers behave low cytotoxicity and good anti-protein performance. Interestingly, APGA-g-PTHF amphiphilic graft copolymers could form homogeneous nanospheres (<250 nm) via self-assembly in H2O/CH2Cl2 medium which could be used for drug (ibuprofen or curcumin) carriers having high drug loading efficiency (∼45%) and fast release behavior. The nanospheres carried curcumin behave very higher (10-fold) anticancer effect against HeLa cells than that of curcumin and thus reduce the harmful drug dosage. Moreover, the nanospheres carried drug might enter into HeLa cells and present pH-sensitive drug release. To the best of our knowledge, this is the first example of PGA-based graft copolymers for highly effective nano-carriers and anti-protein surfaces, which would have a prospect in biomedical areas.

One‐pot orthogonal thiol‐ene click polymerization and ring‐opening grafting reaction of CO2‐based disubstituted δ‐valerolactone

AbstractBeing a disubstituted δ‐valerolactone synthesized by the telomerization of carbon dioxide with 1,3‐butadiene, 3‐ethylidene‐6‐vinyltetrahydro‐2H‐pyran‐2‐one (EVL) contains a six‐membered ring and two unsaturated groups. This report describes the synthesis of an amphiphilic graft copolymer by the combination of thiol‐ene click polymerization and ring‐opening grafting reaction of EVL, ethyldithiol (EDT), and methoxy polyethylene glycol (mPEG‐OH). The alternating copolymer of P(EVL‐alt‐EDT) with 17.9 wt% CO2 content and weight‐average molecular weight (Mw) of 7 kg/mol was prepared by means of the free radical thiol‐ene click polymerization of EVL with EDT initiated by 2,2‐dimethoxy‐1,2‐diphenylethanone under UV irradiation. The following alcoholysis of the lactone ring of P(EVL‐alt‐EDT) backbone by mPEG‐OH is catalyzed by 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene, producing the amphiphilic graft copolymer P(EVL‐alt‐EDT)‐g‐PEG750 with Mw of 12 kg/mol. The polymers are characterized by nuclear magnetic resonance, Fourier transform infrared, matrix‐assisted laser desorption ionization‐time of flight mass spectra, size exclusion chromatography and differential scanning calorimetry. The one‐pot orthogonal strategy is a new utilization of EVL in synthetic polymers and it is significant to the carbon dioxide transformation.

Single-component nanodiscs via the thermal folding of amphiphilic graft copolymers with the adjusted flexibility of the main chain.

Nanodiscs have attracted considerable attention as structural scaffolds for membrane-protein research and as biomaterials in e.g. drug-delivery systems. However, conventional disc-fabrication methods are usually laborious, and disc fabrication via the self-assembly of amphiphiles is difficult. Herein, we report the formation of polymer nanodiscs based on the self-assembly of amphiphilic graft copolymers by adjusting the persistence length of the main chain. Amphiphilic graft copolymers with a series of different main-chain persistence lengths were prepared and these formed, depending on the persistence length, either rods, discs, or vesicles. Notably, polymer nanodiscs were formed upon heating a chilled polymer solution without the need for any additives, and the thus obtained nanodiscs were used to solubilize a membrane protein during cell-free protein synthesis. Given the simplicity of this disc-fabrication method and the ability of these discs to solubilize membrane proteins, this study considerably expands the fundamental and practical scope of graft-copolymer nanodiscs and demonstrates their utility as tools for studying the structure and function of membrane proteins.

Effect of Amphiphilic Graft Co-Polymer Carrier on Solubility and Dissolution Enhancement of Ambrisentan

Aim: Ambrisentan is a endothelin type A selective receptor antagonist used in the management of pulmonary arterial hypertension. Ambrisentan is BCS Class II drug haves very poor solubility in water and shows incomplete absorption after oral administration. The present work was aimed to study the effect of amphiphilic graft co-polymer carrier on enhancement of solubility and dissolution rate of poorly water soluble drug ambrisentan. To improve the aqueous solubility of ambrisentan solid dispersion was formulated by using novel carrier amphiphilic graft co-polymer (Soluplus® ).&#x0D; Materials and Methods: Solid dispersion was prepared by kneading technique by utilizing various ratios of carrier. Obtained solid dispersions ware evaluated for solubility, percentage yield, drug content and in vitro dissolution study. Powder characterization was performed by infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD).&#x0D; Results: FTIR spectroscopy shows no interaction between drug and polymer. DSC study showed that endothermic peak of drug was completely disappeared in Solid dispersion suggesting complete miscibility of drug in Soluplus®. XRD study suggest the conversion of crystalline ambrisentan in to amorphous form. All solid dispersions prepared with Soluplus® as a carrier showed increase in solubility. Solubility of ambrisentan was found to be increased 7.17 fold in optimized SD formulation ASD5. In vitro dissolution study showed the faster drug release from SD formulation compare to its pure form. All solid dispersion formulation’s release more than 50% of drug in first 10 min.&#x0D; Conclusion: This study conclude that the preparation of amphiphilic graft co-polymer based solid dispersion prepared by kneading technique is found to be useful in enhancement the solubility and dissolution rate of ambrisentan.

Synthesis and Self-Assembly of Thermoresponsive Biohybrid Graft Copolymers Based on a Combination of Passerini Multicomponent Reaction and Molecular Recognition.

Amphiphilic graft copolymers exhibit fascinating self-assembly behaviors. Their molecular architectures significantly affect the morphology and functionality of the self-assemblies. Considering the potential application of amphiphilic graft copolymers in the fabrication of nanocarriers, it is essential to synthesize well-defined graft copolymers with desired functional groups. Herein, the Passerini reaction and molecular recognition are introduced to the synthesis of functional thermoresponsive graft copolymers. A bifunctional monomer 2-((adamantan-1-yl)amino)-1-(4-((2-bromo-2-methylpropanoyl)oxy)phenyl)-2-oxoethyl methacrylate (ABMA) with a bromo group for atom transfer radical polymerization (ATRP) and an adamantyl group for molecular recognition is synthesized through the Passerini reaction. The graft copolymers are prepared by reversible addition-fragmentation transfer (RAFT) copolymerization of ABMA and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) followed by RAFT end group removal and ATRP of di(ethylene glycol)methyl ether methacrylate (DEGMA) initiated by the ABMA units. The graft copolymer P(OEGMA-co-ABMA)-g-PDEGMA can be functionalized with β-cyclodextrin modified peptides, affording a thermoresponsive biohybrid graft copolymer. At a temperature above its lower critical solution temperature, the biohybrid graft copolymer self-assembles into peptide-modified polymersomes.

Polyimide-free liquid crystal devices with carbon nanotube-based electrodes

A novel type of polyimide-free liquid crystal (LC) device has been fabricated using layer-by-layer (LBL) deposition of carbon nanotube-based electrodes and in situ formation of self-aligning amphiphilic graft copolymer layer. The LBL-processed organic electrodes showed high transparency comparable to indium tin oxide (ITO) and the self-aligned layer of amphiphilic graft copolymer on organic electrodes provided a stable vertical alignment of LCs. Moreover, the proposed LC device resulted in voltage-dependent driving characteristics suitable for display application. This functional organic electrode layer has potential for application in a flexible display to replace conventional ITO electrode and polyimide alignment layer.

Protein‐Polymer Bioconjugates Prepared by Post‐Polymerization Modification of Alternating Copolymers

AbstractProtein‐polymer bioconjugates have shown great promise in biomedical and life science applications including drug delivery and diagnosis. The current bioconjugation strategies suffer from lack of efficiency and versatility. In this article, poly(styrene‐alt‐maleic anhydride) copolymers were first prepared by RAFT polymerization and characterized by different analytical techniques. Then, the poly(styrene‐alt‐maleic anhydride) precursors were functionalized with primary amine such as azidopropylamine and amino poly(ethylene glycol). The reaction of amino compounds with maleic anhydride was found to be a highly efficient, a versatile, and a facile chemical ligation reaction for the synthesis of macromolecules with quantitative yield under mild conditions. The main benefit is the incorporation of a wide range of functionality by easily changing the primary amine compound. For the amphiphilic graft copolymers based on poly(ethylene glycol), aggregation behavior in water was investigated. In a second part, azido‐functionalized polystyrene copolymers were used to prepare a new protein‐polymer bioconjugate by copper‐free click chemistry reaction.

Characterization of Soluplus/ASC-DP Nanoparticles Encapsulated with Minoxidil for Skin Targeting

Soluplus (Sol) is an amphiphilic graft copolymer capable of forming self-assembled micelles and L-ascorbyl 2,6-dipalmitate (ASC-DP) aggregates spontaneously to form micelles. Micelles are used as drug carriers and can nanoparticulate drugs that are poorly soluble in water, such as minoxidil. The study aimed to prepare minoxidil-encapsulated nanoparticles using Sol/ASC-DP and evaluate their potential for targeted skin application. Sol/ASC-DP nanoparticles or Sol/ASC-DP with minoxidil were prepared using the hydration method, and physical evaluations were carried out, including assessments of particle size and zeta potential. Particle structure was evaluated by transmission electron microscopy (TEM) and 1H-nuclear magnetic resonance spectra to assess particle stability and perform functional evaluations in skin penetration tests. TEM images showed spherical micelle-like particles of approximately 100 nm for Sol/ASC-DP at a 9:1 ratio and of approximately 80 nm for Sol/ASC-DP with incorporated minoxidil at a 9:1:0.5 ratio. Changes were also observed in the solid state, suggesting a hydrophobic interaction between Sol and ASC-DP. In addition, evaporated microparticles (Sol/ASC-DP/minoxidil = 9/1/0.5) improved the skin permeability of minoxidil. These results suggest that Sol/ASC-DP nanoparticles form a stable new nanoparticle due to hydrophobic interactions, which would improve the skin permeability of minoxidil.

Development of polymer-based nanoparticles for zileuton delivery to the lung: PMeOx and PMeOzi surface chemistry reduces interactions with mucins

In this paper, two amphiphilic graft copolymers were synthesized by grafting polylactic acid (PLA) as hydrophobic chain and poly(2-methyl-2-oxazoline) (PMeOx) or poly(2-methyl-2-oxazine) (PMeOzi) as hydrophilic chain, respectively, to a backbone of α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). These original graft copolymers were used to prepare nanoparticles delivering Zileuton in inhalation therapy. Among various tested methods, direct nanoprecipitation proved to be the best technique to prepare nanoparticles with the smallest dimensions, the narrowest dimensional distribution and a spherical shape. To overcome the size limitations for administration by inhalation, the nano-into-micro strategy was applied, encapsulating the nanoparticles in water-soluble mannitol-based microparticles by spray-drying. This process has allowed to produce spherical microparticles with the proper size for optimal lung deposition, and, once in contact with fluids mimicking the lung district, able to dissolve and release non-aggregated nanoparticles, potentially able to spread through the mucus, releasing about 70% of the drug payload in 24 h.