Optimization of Acetalated Dextran–Based Nanocomposite Microparticles for Deep Lung Delivery of Therapeutics via Spray-Drying

Development of Aerosol Dry Powder Chemotherapeutic-Loaded Microparticles for the Treatment of Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide, resulting in the highest mortality rates among both men and women with respect to all other types of cancer. Difficulties in treating lung cancer arise from late-stage diagnoses and tumor heterogeneity and current treatment involves a combination of chemotherapeutics, surgery, and radiation. Chemotherapeutics administered systemically can lead to undesirable side effects and severe off-site toxicity. For example, chronic administration of the chemotherapeutic doxorubicin (DOX) leads to cardiotoxicity, thereby limiting its long-term use. Systemic administration of the highly lipophilic molecule paclitaxel (PTX) is hindered by its water solubility, necessitating the use of solubilizing agents, which can induce side effects. Thus, in this investigation, formulations consisting of spray-dried microparticles (MP) containing DOX and PTX were produced to be administered as dry powder aerosols directly to the lungs. Acetalated dextran (Ac-Dex) was used as the polymer in these formulations, as it is a biocompatible and biodegradable polymer that exhibits pH-responsive degradation. Solid-state characterization revealed that DOX and PTX remained in solubility favoring amorphous states in the MP formulations and that both drugs remained thermally stable throughout the spray drying process. In vitro release studies demonstrated the pH sensitivity of the formulations due to the use of Ac-Dex, as well as the release of both therapeutics over the course of at least 48 h. In vitro aerosol dispersion studies demonstrated that both formulations exhibited suitable aerosol dispersion properties for deep lung delivery.

Wall Materials for Encapsulating Bioactive Compounds via Spray-Drying: A Review

Spray-drying is a continuous encapsulation method that effectively preserves, stabilizes, and retards the degradation of bioactive compounds by encapsulating them within a wall material. The resulting capsules exhibit diverse characteristics influenced by factors such as operating conditions (e.g., air temperature and feed rate) and the interactions between the bioactive compounds and the wall material. This review aims to compile recent research (within the past 5 years) on spray-drying for bioactive compound encapsulation, emphasizing the significance of wall materials in spray-drying and their impact on encapsulation yield, efficiency, and capsule morphology.

Modulating the Pore Architecture of Ice-Templated Dextran Microparticles Using Molecular Weight and Concentration

Spray freeze drying (SFD) is an ice templating method used to produce highly porous particles with complex pore architectures governed by ice nucleation and growth. SFD particles have been advanced as drug carrier systems, but the quantitative description of the morphology formation in the SFD process is still challenging. Here, the pore space dimensions of SFD particles prepared from aqueous dextran solutions of varying molecular weights (40-200 kDa) and concentrations (5-20%) are analyzed using scanning electron microscopy. Coexisting morphologies composed of cellular and dendritic motifs are obtained, which are attributed to variations in the ice growth mechanism determined by the SFD system and modulation of these mechanisms by given precursor solution properties leading to changes in their pore dimensions. Particles with low-aspect ratio cellular pores showing variation of around 0.5-1 μm in diameter with precursor composition but roughly constant with particle diameter are ascribed to a rapid growth regime with high nucleation site density. Image analysis suggests that the pore volume decreases with dextran solid content. Dendritic pores (≈2-20 μm in diameter) with often a central cellular region are identified with surface nucleation and growth followed by a slower growth regime, leading to the overall dendrite surface area scaling approximately linearly with the particle diameter. The dendrite lamellar spacing depends on the concentration according to an inverse power law but is not significantly influenced by molecular weight. Particles with highly elongated cellular pores without lamellar formation show intermediate pore dimensions between the above two limiting morphological types. Analysis of variance and post hoc tests indicate that dextran concentration is the most significant factor in affecting the pore dimensions. The SFD dextran particles herein described could find use in pulmonary drug delivery due to their high porosity and biocompatibility of the matrix material.

Respirable spray dried vancomycin coated magnetic nanoparticles for localized lung delivery

Bacterial pneumonia is a common pulmonary infection responsible for premature death. Biomaterials based-carriers loaded with antibiotics enhance drug potency through localizing the therapy, minimizing the associated adverse effects, and improving patient compliance. Herein, this study reports the preparation of an inhalable dry powder formulation composed of a nano-in-microparticles. Vancomycin was adsorbed on the core of magnetic nanoparticles followed by spray drying into lactose/dextran to optimize the aerodynamic performance and allow the local delivery of the drug into the bacterial pneumonia infection site. Lactose and Dextran are polysaccharides commonly used for pulmonary delivery due to their optimum aerodynamic performance and biocompatibility. The preparation of the nano-in-micro particles with optimum properties was confirmed using FTIR, TEM, SEM, Laser-diffraction, ICP-AES and TGA. The TEM micrographs confirmed the formation of spherical magnetic nanoparticles with a diameter 14.7 ± 5.9 nm and a coating thickness 3 - 16 nm, while laser diffraction showed that outer microparticles exhibited a mean diameter < 5 µm. The formulations demonstrated a promising activity against S. aureus and MRSA and better biocompatibility using MTT assay. In vivo safety and pharmacokinetic studies confirmed the localization of VAN in lung tissue and minimized adverse effects compared to free VAN. Therefore, the developed nano-in-microparticles confers a good potential for eradication of lung infections.

Acetalated dextran based nano- and microparticles: synthesis, fabrication, and therapeutic applications

Acetalated dextran (Ac-DEX) is a pH-responsive dextran derivative polymer. Prepared by a simple acetalation reaction, Ac-DEX has tunable acid-triggered release profile. Despite its relatively short research history, Ac-DEX has shown great potential in various therapeutic applications. Furthermore, the recent functionalization of Ac-DEX makes versatile derivatives with additional properties. Herein, we summarize the cutting-edge development of Ac-DEX and related polymers. Specifically, we focus on the chemical synthesis, nano- and micro-particle fabrication techniques, the controlled-release mechanisms, and the rational design Ac-DEX-based of drug delivery systems in various biomedical applications. Finally, we briefly discuss the challenges and future perspectives in the field.

Spray Drying for the Preparation of Nanoparticle-Based Drug Formulations as Dry Powders for Inhalation

Nanoparticle-based therapeutics have been used in pulmonary formulations to enhance delivery of poorly water-soluble drugs, protect drugs against degradation and achieve modified release and drug targeting. This review focuses on the use of spray drying as a solidification technique to produce microparticles containing nanoparticles (i.e., nanoparticle (NP) agglomerates) with suitable properties as dry powders for inhalation. The review covers the general aspects of pulmonary drug delivery with emphasis on nanoparticle-based dry powders for inhalation and the principles of spray drying as a method for the conversion of nanosuspensions to microparticles. The production and therapeutic applications of the following types of NP agglomerates are presented: nanoporous microparticles, nanocrystalline agglomerates, lipid-based and polymeric formulations. The use of alternative spray-drying techniques, namely nano spray drying, and supercritical CO2-assisted spray drying is also discussed as a way to produce inhalable NP agglomerates.

Development and Evaluation of Paclitaxel-Loaded Aerosol Nanocomposite Microparticles and Their Efficacy Against Air-Grown Lung Cancer Tumor Spheroids

Paclitaxel (as intravenous Taxol) is one of the most applied chemotherapeutics used for the treatment of lung cancer. This project involves the development of a dry powder nanocomposite microparticle (nCmP) aerosol containing PTX-loaded nanoparticles (NP) to be delivered via a dry powder inhaler to the lungs for the treatment of non-small cell lung cancer (NSCLC). Nanoparticles were formulated by a single emulsion and solvent evaporation method, producing smooth, neutral PTX NP of approximately 200 nm in size. PTX nCmP were obtained via spray drying PTX NP with mannitol, producing amorphous wrinkled particles that demonstrated optimal aerosol deposition for in vitro pulmonary delivery. Free PTX, PTX NP, and PTX nCmP were evaluated in vitro in both 2D monolayers and 3D multicellular spheroids (MCS). PTX NP enhanced cytotoxicity when compared to pure drug in the 2D evaluation. However, on a liquid culture 3D tumor spheroid model, PTX NP and pure PTX showed similar efficacy in growth inhibition of MCS. The PTX nCmP formulation had a comparable cytotoxicity impact on MCS compared with free PTX. Finally, PTX nCmP were evaluated in an air-grown 3D MCS platform that mimics the pulmonary environment, representing a new model for the assessment of dry powder formulations.

Sustained release of a model water-soluble compound via dry powder aerosolizable acetalated dextran microparticles

Objective: To design and characterize aerosol microparticles (MP) to provide sustained release of the water-soluble compound sulforhodamine B (SRB) and achieve effective aerosol dispersion. Significance: Modulating the release of water-soluble compounds remains a challenge in pulmonary drug delivery. Methods: SRB and water made up an aqueous solution, while acetalated dextran (Ac-Dex) and isopropyl alcohol made up an organic solution. The two solutions were mixed together, and the solution was spray dried to produce MP. MP were characterized for morphology, size, release kinetics, aerosol dispersion, and cellular interactions. Results: Ac-Dex MP exhibited corrugated morphology and aerodynamic diameters from 2.06 to 2.86 μm. MP deposited in all stages of a Next Generation Impactor, with >90% fine particle fraction. MP exhibited encapsulation efficiencies >129% with SRB loading values up to 16.7 μg SRB/mg MP. MP exhibited sustained release of SRB at pH 7 and fast release at pH 5. In vitro experiments showed minimal cytotoxicity, successful uptake of MP in epithelial cells, and no disruption to the integrity of epithelial monolayers. Conclusions: Ac-Dex MP systems demonstrated the ability to provide sustained the release of a water-soluble therapeutic in addition to effective aerosol dispersion for pulmonary applications.