Impact of particle size and pH on protein corona formation of solid lipid nanoparticles: A proof-of-concept study

When nanoparticles were introduced into the biological media, the protein corona would be formed, which endowed the nanoparticles with new bio-identities. Thus, controlling protein corona formation is critical to in vivo therapeutic effect. Controlling the particle size is the most feasible method during design, and the influence of media pH which varies with disease condition is quite important. The impact of particle size and pH on bovine serum albumin (BSA) corona formation of solid lipid nanoparticles (SLNs) was studied here. The BSA corona formation of SLNs with increasing particle size (120-480 nm) in pH 6.0 and 7.4 was investigated. Multiple techniques were employed for visualization study, conformational structure study and mechanism study, etc. "BSA corona-caused aggregation" of SLN2‒3 was revealed in pH 6.0 while the dispersed state of SLNs was maintained in pH 7.4, which significantly affected the secondary structure of BSA and cell uptake of SLNs. The main interaction was driven by van der Waals force plus hydrogen bonding in pH 7.4, while by electrostatic attraction in pH 6.0, and size-dependent adsorption was confirmed. This study provides a systematic insight to the understanding of protein corona formation of SLNs.

Polymer⁻Surfactant System Based Amorphous Solid Dispersion: Precipitation Inhibition and Bioavailability Enhancement of Itraconazole

The rapid release of poorly water-soluble drugs from amorphous solid dispersion (ASD) is often associated with the generation of supersaturated solution, which provides a strong driving force for precipitation and results in reduced absorption. Precipitation inhibitors, such as polymers and surfactants, are usually used to stabilize the supersaturated solution by blocking the way of kinetic or thermodynamic crystal growth. To evaluate the combined effect of polymers and surfactants on maintaining the supersaturated state of itraconazole (ITZ), various surfactants were integrated with enteric polymer hydroxypropyl methylcellulose acetate succinate (HPMC AS) to develop polymer⁻surfactant based solid dispersion. The supersaturation stability was investigated by in vitro supersaturation dissolution test and nucleation induction time measurement. Compared to the ASD prepared with HPMC AS alone, the addition of d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) exhibited a synergistic effect on precipitation inhibition. The results indicated that the TPGS not only significantly reduced the degree of supersaturation which is the driving force for precipitation, but also provided steric hindrance to delay crystal growth by absorbing onto the surface of small particles. Subsequently, the formulations were evaluated in vivo in beagle dogs. Compared with commercial product Sporanox®, the formulation prepared with HPMC AS/TPGS exhibited a 1.8-fold increase in the AUC (0⁻24 h) of ITZ and a 1.43-fold increase of hydroxyitraconazole (OH-ITZ) in the plasma. Similarly, the extent of absorption was increased by more than 40% when compared to the formulation prepared with HPMC AS alone. The results of this study demonstrated that the ASD based on polymer⁻surfactant system could obviously inhibit drug precipitation in vitro and in vivo, which provides a new access for the development of ASD for poorly water-soluble drug.

Inhalable Biomineralized Liposomes for Cyclic Ca2+-Burst-Centered Endoplasmic Reticulum Stress Enhanced Lung Cancer Ferroptosis Therapy

Lung cancer with the highest mortality poses a great threat to human health. Ferroptosis therapy has recently been raised as a promising strategy for lung cancer treatment by boosting the reactive species (ROS) production and lipid peroxidation (LPO) accumulation intracellularly. However, the insufficient intracellular ROS level and the unsatisfactory drug accumulation in lung cancer lesions hamper the efficacy of ferroptosis therapy. Here, an inhalable biomineralized liposome LDM co-loaded with dihydroartemisinin (DHA) and pH-responsive calcium phosphate (CaP) was constructed as a ferroptosis nanoinducer for achieving Ca2+-burst-centered endoplasmic reticulum (ER) stress enhanced lung cancer ferroptosis therapy. Equipped with excellent nebulization properties, about 6.80-fold higher lung lesions drug accumulation than intravenous injection made the proposed inhalable LDM an ideal nanoplatform for lung cancer treatment. The Fenton-like reaction mediated by DHA with peroxide bridge structure could contribute to intracellular ROS production and induce ferroptosis. Assisted by DHA-mediated sarco-/endoplasmic reticulum calcium ATPase (SERCA) inhibition, the initial Ca2+ burst caused by CaP shell degradation triggered the Ca2+-mediated intense ER stress and subsequently induced mitochondria dysfunction to further boost ROS accumulation, which strengthens ferroptosis. The second Ca2+ burst occurred as a result of Ca2+ influx through ferroptotic pores on cell membranes, thus sequentially constructing the lethal "Ca2+ burst-ER stress-ferroptosis" cycle. Consequently, the Ca2+-burst-centered ER stress enhanced ferroptosis process was confirmed as a cell swelling and cell membrane disruption process driven by notable intracellular ROS and LPO accumulation. The proposed LDM showed an encouraging lung retention property and extraordinary antitumor ability in an orthotropic lung tumor murine model. In conclusion, the constructed ferroptosis nanoinducer could be a potential tailored nanoplatform for nebulization-based pulmonary delivery and underscore the application of Ca2+-burst-centered ER stress enhanced lung cancer ferroptosis therapy.

PLGA Porous Microspheres Dry Powders for Codelivery of Afatinib-Loaded Solid Lipid Nanoparticles and Paclitaxel: Novel Therapy for EGFR Tyrosine Kinase Inhibitors Resistant Nonsmall Cell Lung Cancer

Combination therapy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR TKIs) with other chemotherapeutic agents is a feasible strategy to overcome resistance that often occurs after 9-13 months of EGFR TKIs administration in nonsmall cell lung cancer (NSCLC). In this study, a pulmonary microspheres system that codelivers afatinib and paclitaxel (PTX) is developed for treatment of EGFR TKIs resistant NSCLC. In this system, afatinib is loaded in stearic acid-based solid lipid nanoparticles, then these nanoparticles and PTX are loaded in poly-lactide-co-glycolide-based porous microspheres. These inhaled microspheres systems are characterized including geometric particle size, drug encapsulation efficiency, morphology by scanning electron microscopy, specific surface area, in vitro drug release, and aerodynamic particle size. Cell experiments indicate that afatinib and PTX have a synergistic effect and the codelivery system shows a superior treatment effect in drug-resistant NSCLC cells. The biocompatibility, pharmacokinetic, and tissue distribution experiments in Sprague-Dawley rats show that afatinib and PTX in the system can maintain 96 h of high lung concentration but low concentration in other tissues, with acceptable safety. These results demonstrate that this system may be a prospective delivery strategy for drug combination treatment in cancers developing resistance, especially drug-resistant lung cancer.

Pulmonary delivery nanomedicines towards circumventing physiological barriers: Strategies and characterization approaches

Pulmonary delivery of nanomedicines is very promising in lung local disease treatments whereas several physiological barriers limit its application via the interaction with inhaled nanomedicines, namely bio-nano interactions. These bio-nano interactions may affect the pulmonary fate of nanomedicines and impede the distribution of nanomedicines in its targeted region, and subsequently undermine the therapeutic efficacy. Pulmonary diseases are under worse scenarios as the altered physiological barriers generally induce stronger bio-nano interactions. To mitigate the bio-nano interactions and regulate the pulmonary fate of nanomedicines, a number of manipulating strategies were established based on size control, surface modification, charge tuning and co-delivery of mucolytic agents. Visualized and non-visualized characterizations can be employed to validate the robustness of the proposed strategies. This review provides a guiding overview of the physiological barriers affecting the in vivo fate of inhaled nanomedicines, the manipulating strategies, and the validation methods, which will assist with the rational design and application of pulmonary nanomedicine.

Inhalable solid lipid nanoparticles for intracellular tuberculosis infection therapy: macrophage-targeting and pH-sensitive properties

Mycobacterium tuberculosis (MTB) is one of the most threatening pathogens for its latent infection in macrophages. The intracellular MTB isolated itself from drugs and could spread via macrophages. Therefore, a mannose-modified macrophage-targeting solid lipid nanoparticle, MAN-IC-SLN, loading the pH-sensitive prodrug of isoniazid (INH), was designed to treat the latent tuberculosis infection. The surface of SLNs was modified by a synthesized 6-octadecylimino-hexane-1,2,3,4,5-pentanol (MAN-SA) to target macrophages, and the modified SLNs showed a higher cell uptake in macrophages (97.2%) than unmodified SLNs (42.4%). The prodrug, isonicotinic acid octylidene-hydrazide (INH-CHO), was synthesized to achieve the pH-sensitive release of INH in macrophages. The INH-CHO-loaded SLNs exhibited a pH-sensitive release profile and accomplished a higher accumulated release in pH 5.5 media (82.63 ± 2.12%) compared with the release in pH 7.4 media (58.83 ± 3.84%). Mycobacterium smegmatis was used as a substitute for MTB, and the MAN-IC-SLNs showed a fourfold increase of intracellular antibiotic efficacy and enhanced macrophage uptake because of the pH-sensitive degradation of INH-CHO and MAN-SA in SLNs, respectively. For the in vivo antibiotic efficacy test, the SLNs group displayed an 83% decrease of the colony-forming unit while the free INH group only showed a 60% decrease. The study demonstrates that macrophage targeting and pH-sensitive SLNs can be used as a promising platform for the latent tuberculosis infection. Graphical Abstract Table of contents: Macrophage-targeting and pH-sensitive solid lipid nanoparticles (SLN) were administrated to the lung via nebulization. Macrophage targeting was achieved by appropriate particle size and surface mannose modification with synthesized MAN-SA. After being swallowed by macrophages, the prodrug, Isonicotinic acid octylidene-hydrazide (INH-CHO), quickly released isoniazid, which was triggered by the intracellular acid environment. The SLNs exhibited higher intracellular antibiotic efficacy due to their macrophage-targeting and pH-sensitive properties.

Thermo-sensitive gel in glaucoma therapy for enhanced bioavailability: In vitro characterization, in vivo pharmacokinetics and pharmacodynamics study

AIMS

Glaucoma is a chronic ophthalmic disease, which has become one of the leading causes to progressive and irreversible blindness. Current ophthalmic drug delivery to treat glaucoma is mostly eyedrop, whose rapid elimination on corneal surface can lead to poor bioavailability. The present study was aimed to develop a timolol maleate loaded thermo-sensitive gel (TM-TSG) with improved bioavailability to treat glaucoma.

MAIN METHODS

TM-TSG was prepared by homogeneously dispersing 0.3% (w/v) timolol maleate, 24.25% (w/v) poloxamer 407 (P407) and 1.56% (w/v) poloxamer 188 (P188) into phosphate buffer solution (pH = 7.4) and the formulated TM-TSG was characterized.

KEY FINDINGS

TM-TSG was stored in liquid form at room temperature (25 °C) and transited to semisolid gel at physiological temperature (32 °C). The rheological property of TM-TSG was in favor of uniform distribution of drug. TM-TSG showed good stability at different conditions including centrifugation, autoclaving and different temperature. In vivo pharmacokinetic studies indicated that TM-TSG could enhance absorption of TM in aqueous humor and improve the ocular bioavailability in comparison of commercial TM eyedrops. In vivo experiment result showed that TM-TSG had greater effect in treating glaucoma than TM eyedrops by sustainably lowering intraocular pressure (IOP) for a week. Moreover, slit lamp test and histopathological analysis demonstrated that TM-TSG had excellent biocompatibility.

SIGNIFICANCE

TM-TSG could be a promising ophthalmic delivery system for glaucoma therapy.

Self-assembling in situ gel based on lyotropic liquid crystals containing VEGF for tissue regeneration

Current tissue-regenerative biomaterials confront two critical issues: the uncontrollable delivery capacity of vascular endothelial growth factor (VEGF) for adequate vascularization and the poor mechanical properties of the system for tissue regeneration. To overcome these two issues, a self-assembling in situ gel based on lyotropic liquid crystals (LLC) was developed. VEGF-LLC was administrated as a precursor solution that would self-assemble into an in situ gel with well-defined internal inverse bicontinuous cubic phases when exposed to physiological fluid at a defect site. The inverse cubic phase with a 3D bicontinuous water channel enabled a 7-day sustained release of VEGF. The release profile of VEGF-LLC was controlled using octyl glucoside (OG) as a hydration-modulating agent, which could enlarge the water channel, yielding a 2-fold increase in water channel size and a 7-fold increase in VEGF release. For the mechanical properties, the elastic modulus was found to decrease from ∼100 kPa to ∼1.2 kPa, which might be more favorable for angiogenesis. Furthermore, the self-recovery ability of the VEGF-LLC gel was confirmed by quick recovery of the inner network in step-strain measurements. In vitro, VEGF-LLC considerably promoted the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) as compared to free VEGF (p < 0.05). Furthermore, angiogenesis was successfully induced in rats after subcutaneous injection of VEGF-LLC. The self-assembling LLC gel showed satisfactory degradability and mild inflammatory response with little impact on the surrounding tissue. The controllable release profile and unique mechanical properties of VEGF-LLC offer a new approach for tissue regeneration. STATEMENT OF SIGNIFICANCE: The potential clinical use of currently available biomaterials in tissue regeneration is limited by their uncontrollable drug delivery capacity and poor mechanical properties. Herein, a self-assembling in situ gel based on lyotropic liquid crystals (LLC) for induced angiogenesis was developed. The results showed that the addition of octyl glucoside (OG) could change the water channel size of LLC, which enabled the LLC system to release VEGF in a sustained manner and to possess a suitable modulus to favor angiogenesis simultaneously. Moreover, the self-recovery capability allowed the gel to match the deformation of surrounding tissues during body motion to maintain its properties and reduce discomfort. In vivo, angiogenesis was induced by VEGF-LLC 14 days after administering subcutaneous injection. These results highlight the potential of LLC as a promising sustained protein drug delivery system for vascular formation and tissue regeneration.

Moisture-Resistant Co-Spray-Dried Netilmicin with l-Leucine as Dry Powder Inhalation for the Treatment of Respiratory Infections

Netilmicin (NTM) is one of the first-line drugs for lower respiratory tract infections (LRTI) therapy, but its nephrotoxicity and ototoxicity caused by intravenous injection restrict its clinical application. Dry powder inhalation (DPI) is a popular local drug delivery system that is introduced as a solution. Due to the nature of NTM hygroscopicity that hinders its direct use through DPI, in this study, L-leucine (LL) was added into NTM dry powder to reduce its moisture absorption rate and improve its aerosolization performance. NTM DPIs were prepared using spray-drying with different LL proportions. The particle size, density, morphology, crystallinity, water content, hygroscopicity, antibacterial activity, in vitro aerosolization performance, and stability of each formulation were characterized. NTM DPIs were suitable for inhalation and amorphous with a corrugated surface. The analysis indicated that the water content and hygroscopicity were decreased with the addition of LL, whilst the antibacterial activity of NTM was maintained. The optimal formulation ND₂ (NTM:LL = 30:1) showed high fine particle fraction values (85.14 ± 8.97%), which was 2.78-fold those of ND₀ (100% NTM). It was stable after storage at 40 ± 2 °C, 75 ± 5% relative humidity (RH). The additional LL in NTM DPI successfully reduced the hygroscopicity and improved the aerosolization performance. NTM DPIs were proved to be a feasible and desirable approach for the treatment of LRTI.

Development of fine solid-crystal suspension with enhanced solubility, stability, and aerosolization performance for dry powder inhalation

Dry powder for inhalation (DPI) is an attractive approach for the treatment of local lung diseases. However, the application of drugs with poor water solubility is often limited due to the dissolution obstacles in the fluid layer of the lung lining. In this study, fine solid-crystal suspension (FSCS) was proposed as a solvent-free method to improve the solubility of a drug with poor solubility (itraconazole) and achieve high deposition efficiency simultaneously. The FSCS, in which the crystalline drug particle was highly dispersed in the crystalline excipient, was initially prepared as drug-excipient extrudate by hot melt extrusion, followed by jet milling into fine particles. Unlike the amorphous solid dispersion in the high-energy state, which is liable to recrystallize and aggregate, the FSCS was expected not only to improve the solubility of itraconazole, but also to maintain excellent physical stability. As evidenced in the solubility and stability studies, the solubility of itraconazole in the FSCS was approximately 145-fold greater than that of the raw material, and the crystalline form of itraconazole in the FSCS was also unchanged after storage in the accelerated condition for 6 months (40°C and 75% relative humidity [RH]). The improved solubility might be ascribed to the reduced crystal size and increased wettability, as confirmed by the particle size and contact angle test. The FSCS also showed an encouragingly high fine-particle fraction of 50.59±0.67%, which might have benefited from the appropriate particle size. Therefore, the FSCS was suggested as a promising DPI for delivery of drugs with poor water solubility.

Taste-masking and colloidal-stable cubosomes loaded with Cefpodoxime proxetil for pediatric oral delivery

Drug administration failure has been often witnessed in pediatric due to children's resistance to take medicines with bitter taste. Taste-masking is the key requirement among the scanty drugs available for children. Solid taste-masking systems, such as tablets and capsules, are difficult to swallow for children. Therefore, a liquid taste-masking system based on lyotropic liquid crystalline nanoparticles (LLCNs) was developed in this study. Cefpodoxime proxetil (CFP), a typically bitter drug used as antibiotic in pediatric, was selected as the model drug, and the encapsulation of CFP into the LLCNs was envisaged to improve their taste. Pluronic F127 was added to improve the colloidal stability of CFP-LLCNs. The optimized CFP-LLCNs showed the particle size of 187.29 ± 4.12 nm and the encapsulation efficiency of 85.80%. The mesophase analysis by polarized light microscopy and small angle X-ray scattering confirmed the cubic phase of CFP-LLCNs. It showed a sustained-release profile well fitted to Higuchi model, indicating that diffusion and erosion were both responsible for the CFP release. The taste-masking ability of CFP-LLCNs was confirmed by electronic tongue, compared to CFP and commercial product. The colloidal stability was verified after 3 months storage in room condition (25 ± 2 °C, 70 ± 2%RH). To sum up, the taste-masking and colloidal-stable CFP-LLCNs showed great potential for pediatric oral delivery.

Nanoporous mannitol carrier prepared by non-organic solvent spray drying technique to enhance the aerosolization performance for dry powder inhalation

An optimum carrier rugosity is essential to achieve a satisfying drug deposition efficiency for the carrier based dry powder inhalation (DPI). Therefore, a non-organic spray drying technique was firstly used to prepare nanoporous mannitol with small asperities to enhance the DPI aerosolization performance. Ammonium carbonate was used as a pore-forming agent since it decomposed with volatile during preparation. It was found that only the porous structure, and hence the specific surface area and carrier density were changed at different ammonium carbonate concentration. Furthermore, the carrier density was used as an indication of porosity to correlate with drug aerosolization. A good correlation between the carrier density and fine particle fraction (FPF) (r2 = 0.9579) was established, suggesting that the deposition efficiency increased with the decreased carrier density. Nanoporous mannitol with a mean pore size of about 6 nm exhibited 0.24-fold carrier density while 2.16-fold FPF value of the non-porous mannitol. The enhanced deposition efficiency was further confirmed from the pharmacokinetic studies since the nanoporous mannitol exhibited a significantly higher AUC0-8h value than the non-porous mannitol and commercial product Pulmicort. Therefore, surface modification by preparing nanoporous carrier through non-organic spray drying showed to be a facile approach to enhance the DPI aerosolization performance.

Low density, good flowability cyclodextrin-raffinose binary carrier for dry powder inhaler: anti-hygroscopicity and aerosolization performance enhancement

BACKGROUND

The hygroscopicity of raffinose carrier for dry powder inhaler (DPI) was the main obstacle for its further application. Hygroscopicity-induced agglomeration would cause deterioration of aerosolization performance of raffinose, undermining the delivery efficiency.

METHODS

Cyclodextrin-raffinose binary carriers (CRBCs) were produced by spray-drying so as to surmount the above issue. Physicochemical attributes and formation mechanism of CRBCs were explored in detail. The flow property of CRBCs was examined by FT4 Powder Rheometer. Hygroscopicity of CRBCs was elucidated by dynamic vapor sorption study. Aerosolization performance was evaluated by in vitro deposition profile and in vivo pharmacokinetic profile of CRBC based DPI formulations.

RESULTS

The optimal formulation of CRBC (R4) was proven to possess anti-hygroscopicity and aerosolization performance enhancement properties. Concisely, the moisture uptake of R4 was c.a. 5% which was far lower than spray-dried raffinose (R0, c.a. 65%). R4 exhibited a high fine particle fraction value of 70.56 ± 0.61% and it was 3.75-fold against R0. The pulmonary and plasmatic bioavailability of R4 were significantly higher than R0 (p < 0.05).

CONCLUSION

CRBC with anti-hygroscopicity and aerosolization performance enhancement properties was a promising approach for pulmonary drug delivery, which could provide new possibilities to the application of hygroscopic carriers for DPI.

Relationship between particle size and lung retention time of intact solid lipid nanoparticle suspensions after pulmonary delivery

The relationship between the particle size and lung retention time of inhaled nanocarriers was unclear, and this uncertainty hampered the design of nanocarriers for pulmonary delivery. The debate resulted from a lack of knowledge regarding the integrity of the involved nanocarriers. A distinguishable bioimaging probe which could differentiate between integrated and disintegrated nanocarriers by emitting different signals was introduced to address this problem. The aza-BODIPY structured aggregation-caused quenching (ACQ) probes were promising candidates, because they showed intense fluorescence signals in intact nanocarriers while quenched after the decomposition of nanocarriers. This attribute was called an on-off switch. In this paper, ACQ probes were encapsulated into a solid lipid nanoparticle suspension (SLNS) with different particle sizes (120-480 nm), and the relationship between particle size and lung retention time after pulmonary delivery was investigated in BALB/c mice. The results showed that a larger particle size led to a longer lung retention time. By comparing with the results of a non-water-quenching probe, the SLNS systems were found to be mostly intact in the pulmonary region. These findings will serve as a firm basis for the design and development of nanocarriers for pulmonary delivery.

Anhydrous reverse micelle nanoparticles: new strategy to overcome sedimentation instability of peptide-containing pressurized metered-dose inhalers

The objective of this study was to develop a novel anhydrous reverse micelle nanoparticles (ARM-NPs) system to overcome the sedimentation instability of peptide-containing pressurized metered-dose inhalers (pMDIs). A bottom-up method was utilized to fabricate ARM-NPs. Tertiary butyl alcohol (TBA)/water system, freeze-drying and lipid inversion method were successively used to produce the ARM-NPs for pMDI. Various characteristics of ARM-NPs were investigated including particle size, morphology, secondary structure of the peptide drug, aerosolization properties and storage stability. As revealed by the results, ARM-NPs with spherical shape possessed 147.7 ± 2.0 nm of particle size with 0.152 ± 0.021 PdI. The ARM-NPs for pMDI had satisfactory fine particle fraction (FPF) value of 46.99 ± 1.33%, while the secondary structure of the peptide drug was unchanged. Stability tests showed no pronounced sedimentation instability for over 12 weeks at 4-6 °C. Furthermore, a hypothesis was raised to explain the formation mechanism of ARM-NPs, which was verified by the differential scanning calorimetry analysis. The lecithin employed in the reverse micelle vesicles could serve as a steric barrier between peptide drugs and bulk propellant, which prevented the instability of peptide drugs in hydrophobic environment. Homogenous particle size could avoid Ostwald ripening phenomenon of particles in pMDIs. It was concluded that the ARM-NPs for pMDI could successfully overcome sedimentation instability by the steric barrier effect and homogeneous particle size.

Inhalable Biomimetic Protein Corona-Mediated Nanoreactor for Self-Amplified Lung Adenocarcinoma Ferroptosis Therapy

Ferroptosis therapy by catalyzing the Fenton reaction has emerged as a promising tumor elimination strategy for lung adenocarcinoma (ADC). However, the unsatisfactory Fenton reaction efficiency, strong intracellular antioxidant system, and insufficient lung drug accumulation limits the ferroptosis therapeutic effect. To address these issues, an inhalable nanoreactor was proposed by spontaneously adsorbing biomimetic protein corona (PC) composed of matrix metalloproteinase 2 responsive gelatin and glutamate (Glu) on the surface of cationic nanostructured lipid carriers (NLC) core loaded with ferrocene (Fc) and fluvastatin. The prepared Fc-NLC(F)@PC could be nebulized into lung lesions with 2.6 times higher drug accumulation and boost lipid peroxide production by 3.2 times to enhance ferroptosis therapy. Mechanically, fluvastatin was proved to inhibit monocarboxylic acid transporter 4 mediated lactate efflux, inducing tumor acidosis to boost Fc-catalyzing reactive oxygen species production, while the extracellular elevating Glu concentration was found to inhibit xCT (system Xc-) functions and further collapse the tumor antioxidant system by glutathione synthesis suppression. Mitochondrial dysfunction and cell membrane damage were involved in the nanoreactor-driven ferroptotic cell death process. The enhanced antitumor effects by combination of tumor acidosis and antioxidant system collapse were confirmed in an orthotopic lung ADC tumor model. Overall, the proposed nanoreactor highlights the pulmonary delivery approach for local lung ADC treatment and underscores the great potential of ferroptosis therapy.

Novel approach for real-time monitoring of carrier-based DPIs delivery process via pulmonary route based on modular modified Sympatec HELOS

An explicit illustration of pulmonary delivery processes (PDPs) was a prerequisite for the formulation design and optimization of carrier-based DPIs. However, the current evaluation approaches for DPIs could not provide precise investigation of each PDP separately, or the approaches merely used a simplified and idealized model. In the present study, a novel modular modified Sympatec HELOS (MMSH) was developed to fully investigate the mechanism of each PDP separately in real-time. An inhaler device, artificial throat and pre-separator were separately integrated with a Sympatec HELOS. The dispersion and fluidization, transportation, detachment and deposition processes of pulmonary delivery for model DPIs were explored under different flow rates. Moreover, time-sliced measurements were used to monitor the PDPs in real-time. The Next Generation Impactor (NGI) was applied to determine the aerosolization performance of the model DPIs. The release profiles of the drug particles, drug aggregations and carriers were obtained by MMSH in real-time. Each PDP of the DPIs was analyzed in detail. Moreover, a positive correlation was established between the total release amount of drug particles and the fine particle fraction (FPF) values (R 2 = 0.9898). The innovative MMSH was successfully developed and was capable of illustrating the PDPs and the mechanism of carrier-based DPIs, providing a theoretical basis for the design and optimization of carrier-based DPIs.

In situ gelation of rhEGF-containing liquid crystalline precursor with good cargo stability and system mechanical properties: a novel delivery system for chronic wounds treatment

The objective of this study was to develop a novel delivery system for recombinant human epidermal growth factor (rhEGF) for chronic wound treatment. Such a delivery system should be of good cargo stability and system mechanical properties in order to guarantee a satisfactory wound-healing effect. rhEGF-containing lyotropic liquid crystalline precursors (rhEGF-LLCPs) with in situ gelation capability were considered as a promising candidate to achieve this aim. Various properties of the optimal formulations (rhEGF-LLCP1 and rhEGF-LLCP2) were characterized, including apparent viscosity, gelation time, in vitro release and phase behavior. The stability of rhEGF and system mechanical properties (i.e. mechanical rigidity and bioadhesive force) were verified. Interestingly, rhEGF-LLCP2 with a larger internal water channel diameter exhibited faster release rate in vitro and then better bioactivity in Balb/c 3T3 and HaCaT cell models. Moreover, rhEGF-LLCP2 showed distinct promotion effects on wound closure, inflammatory recovery and re-epithelization process in Sprague-Dawley rat models. In conclusion, rhEGF-LLCP emerged as a prospective candidate to preserve the stability and enhance the wound-healing effect of rhEGF, which might serve as a new delivery system for chronic wound therapies.

Engineering Ferroptosis Inhibitors as Inhalable Nanomedicines for the Highly Efficient Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) refers to chronic progressive fibrotic interstitial pneumonia. It is called a "tumor-like disease" and cannot be cured using existing clinical drugs. Therefore, new treatment options are urgently needed. Studies have proven that ferroptosis is closely related to the development of IPF, and ferroptosis inhibitors can slow down the occurrence of IPF by chelating iron or reducing lipid peroxidation. For example, the ferroptosis inhibitor deferoxamine (DFO) was used to treat a mouse model of pulmonary fibrosis, and DFO successfully reversed the IPF phenotype and increased the survival rate of mice from 50% to 90%. Given this, we perceive that the treatment of IPF by delivering ferroptosis inhibitors is a promising option. However, the delivery of ferroptosis inhibitors faces two bottlenecks: low solubility and targeting. For one thing, we consider preparing ferroptosis inhibitors into nanomedicines to improve solubility. For another thing, we propose to deliver nanomedicines through pulmonary drug-delivery system (PDDS) to improve targeting. Compared with oral or injection administration, PDDS can achieve better delivery and accumulation in the lung, while reducing the systemic exposure of the drug, and is an efficient and safe drug-delivery method. In this paper, three possible nanomedicines for PDDS and the preparation methods thereof are proposed to deliver ferroptosis inhibitors for the treatment of IPF. Proper administration devices and challenges in future applications are also discussed. In general, this perspective proposes a promising strategy for the treatment of IPF based on inhalable nanomedicines carrying ferroptosis inhibitors, which can inspire new ideas in the field of drug development and therapy of IPF.

Co-spray-dried poly-L-lysine with L-leucine as dry powder inhalations for the treatment of pulmonary infection: Moisture-resistance and desirable aerosolization performance

Poly-L-lysine (PLL) is a promising candidate for the treatment of pulmonary infection with lower occurrence of drug-resistance due to its unique antibacterial mechanisms. Dry powder inhalations (DPIs) are considered as the first choice for formulating PLL to treat pulmonary infection on account of direct delivery and satisfactory stability. However, hygroscopicity of PLL limited its therapeutic effect on pulmonary infection when PLL developed into DPIs. The hygroscopicity caused two obstacles including the low drug deposition in the lower respiratory tract and undesirable aerosolization performance deterioration. In this study, PLL was co-spray-dried with L-leucine (LL) to achieve moisture-resistance and desirable aerosolization performance. The ratio of PLL and LL was optimized to obtain particles with different morphology, hygroscopicity and aerodynamic properties. The obtained PLL DPIs were suitable for inhalation with a corrugated surface formed by hydrophobic LL. The anti-hygroscopicity, aerosolization performance and rheological properties of P2 DPIs were optimal when PLL:LL = 85:15. The DPIs particles were stable after being stored at high relative humidity (60 ± 5%), and their superiority in treating pulmonary infections was also proved by in vitro and in vivo experiments. The established PLL DPIs were proved to be a feasible and desirable approach to treat pulmonary infections.

Improved Gene Transfer with Functionalized Hollow Mesoporous Silica Nanoparticles of Reduced Cytotoxicity

Gene therapy is a promising strategy for treatment of genetically caused diseases. Successful gene delivery requires an efficient carrier to transfer the desired gene into host cells. Recently, mesoporous silica nanoparticles (MSNs) functionalized with 25 kD polyethyleneimine (PEI) were extensively used as gene delivery carriers. However, 25 kD PEI could significantly reduce the safety of the modified MSNs although it is efficient for intracellular delivery of nucleic acids. In addition, limited drug loading remains a challenge for conventional MSNs drug carriers. Hollow mesoporous silica nanoparticles (HMSNs) with high pore volume, tunable pore size, and excellent biocompatibility are attractive alternatives. To make them more efficient, a less toxic 1.8 kD PEI polymer was used to functionalize the HMSNs which have large pore size (~10 nm) and form PEI-HMSNs. Scanning and transmission electron microscopic images showed that HMSNs were spherical in shape and approximately 270 nm in diameter with uniform hollow nanostructures. The maximum loading capacity of green fluorescent protein labeled DNA (GFP-DNA) in PEI-HMSNs was found to be 37.98 mg/g. The loading capacity of PEI-HMSNs was nearly three-fold higher than those of PEI modified solid nanoparticles, indicating that both hollow and large pores contributed to the increase in DNA adsorption. The transfection of GFP-DNA plasmid loaded in PEI-HMSNs was increased two-fold in comparison to that of 25 kD PEI. MTT assays in Lovo cells showed that the cell viability was more than 85% when the concentration of PEI-HMSNs was 120 µg/mL, whereas the cell viability was less than 20% when the 25 kD PEI was used at the same concentration. These results indicated that PEI-HMSNs could be used as a delivery system for nucleic acids due to good biocompatibility, high gene loading capacity, and enhanced gene transfer efficiency.

Dry powder inhaler formulations of poorly water-soluble itraconazole: A balance between in-vitro dissolution and in-vivo distribution is necessary

Formulating poorly water-soluble drug, itraconazole (ITZ), as dry powder inhaler (DPI) may be more effective for the treatment of invasive pulmonary Aspergillosis than intravenous injection and oral administration. It is necessary to improve the dissolution of ITZ because the alveolar lining fluid is limited and thus the dissolution of ITZ in the lung may be slow and incomplete. However, too fast dissolution may result in over-absorption into the circulation and thus insufficient distribution in the lung. The purpose of this study is to understand the relationship between in-vitro dissolution and in-vivo distribution of ITZ from DPI formulations. Two DPI formulations (F1 and F2) with identical compositions and similar aerodynamic behaviors were fabricated by hot melt extrusion and thus jet-milling. ITZ was formulated with mannitol as fine solid crystal suspension system to effectively improve its dissolution. In-vitro dissolution tests and in-vivo pharmacokinetic studies indicated that F1 released faster than F2 under both sink and non-sink conditions, but exhibited a lower lung retention and higher plasma absorption than F2. These results suggested that although dissolution enhancement of poorly water-soluble drugs in pulmonary delivery may be necessary to overcome problems such as local irritation and quick elimination by macrophages, it may have an impact on the distribution of the drug between the lung and the plasma. A balance between airway dissolution and systemic absorption should be taken into consideration when developing DPI formulations of poorly water-soluble ITZ.

Novel Inhalable Ciprofloxacin Dry Powders for Bronchiectasis Therapy: Mannitol-Silk Fibroin Binary Microparticles with High-Payload and Improved Aerosolized Properties

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic respiratory disease associated with the high morbidity and mortality. Long-term intermittent therapy by inhalable antibiotics has recently emerged as an effective approach for NCFB treatment. However, the effective delivery of antibiotics to the lung requires administering a high dose to the site of infection. Herein, we investigated the novel inhalable silk-based microparticles as a promising approach to deliver high-payload ciprofloxacin (CIP) for NCFB therapy. Silk fibroin (SF) was applied to improve drug-payload and deposit efficiency of the dry powder particles. Mannitol was added as a mucokinetic agent. The dry powder inhaler (DPI) formulations of CIP microparticles were evaluated in vitro in terms of the aerodynamic performance, particle size distribution, drug loading, morphology, and their solid state. The optimal formulation (highest drug loading, 80%) exhibited superior aerosolization performance in terms of fine particle fraction (45.04 ± 0.84%), emitted dose (98.10 ± 1.27%), mass median aerodynamic diameter (3.75 ± 0.03 μm), and geometric standard deviation (1.66 ± 0.10). The improved drug loading was due to the electrostatic interactions between the SF and CIP by adsorption, and the superior aerosolization efficiency would be largely attributed to the fluffy and porous cotton-like property and low-density structure of SF. The presented results indicated the novel inhalable silk-based DPI microparticles of CIP could provide a promising strategy for the treatment of NCFB.