Pulmonary drug delivery is a well-suited approach for treating lung infections, providing direct and targeted treatment to infected cells. This method enhances drug concentration in the lungs while reducing the required dosage. However, the physiological characteristics of the lungs constitute a complex barrier to drug delivery. Conventional methods often underperform or fail completely, particularly with poorly soluble drugs and inhaled proteins. This thesis explores the use of mesoporous silica particles (MSPs) as sole excipient in dry powder formulations to improve the treatment of lung infections. This study investigated the use of micron-sized mesoporous silica particles (MSPs) as a drug vehicle for clofazimine (CLZ) to target the lung. In simulated lung fluid (SLF), CLZ was released from the MSPs and subsequently formed nanoparticles. This micro-nano strategy significantly enhanced both extracellular and intracellular bactericidal efficacy in relation to mycobacteria, demonstrating its potential for multidrug-resistant TB. This formulation ensured high local drug retention and minimal side effects, indicating that lower CLZ doses could be administered relative to current oral treatment while sustaining adequate antimicrobial concentrations in the lungs. A second study demonstrated the use of MSPs in formulating proteins, specifically lysozyme (LYS), as a dry powder inhaler (DPI), while also examining aerosolization and release profiles. The observed protein lung deposition and preserved enzymatic activity post-release underscored the versatility of MSPs in this therapeutic application. The toxicological effects of MSPs were evaluated, with a focus on whether silica with varying dissolution characteristics influences cell viability and drug release (CLZ). All types of soluble silica exhibited low immunological responses, emphasizing the potential and safety of amorphous silica for pulmonary drug delivery. A further innovation in this thesis was the design of bioinspired lung surfactantcoated MSPs, aimed at enhancing CLZ dissolution and improving particle interaction and transport in mucus and bronchial tissue. Finally, the MSPs coating concept was refined using bacterial lipids from mycobacteria to assess whether the antimicrobial activity of CLZ against mycobacteria could be improved, presenting a novel approach for treating lung infections. Overall, this thesis highlights the potential of bioinspired coated MSPs as an advanced drug delivery system to address unmet challenges in treating respiratory infections and in overcoming antimicrobial resistance. 

Administrering av läkemedel via lungorna är en lovande strategi för behandling av lunginfektioner, eftersom den möjliggör en direkt och målinriktad behandling av infekterade celler. Detta ökar läkemedelskoncentrationen i lungorna och minskar den erforderliga dosen. Lungornas fysiologiska egenskaper utgör dock en komplex barriär för läkemedelsadministrering. Traditionella metoder har ofta begränsad effektivitet, särskilt när det gäller svårlösliga läkemedel och vid proteinbaserade terapier. I denna avhandling undersöks användningen av mesoporösa kiseldioxidpartiklar (MSP) som enda hjälpämne i torrpulverformuleringar, med målet att bidra till behandlingen av lunginfektioner.

Mikrometerstora mesoporösa kiseldioxidpartiklar (MSPs) undersöktes som bärare för klofazimin (CLZ) med syfte att leverera läkemedlet till lungorna. I simulerad lungvätska (SLF) frigjordes CLZ och bildade nanopartiklar. Denna mikro-nano-strategi förbättrade avsevärt både extracellulär och intracellulär avdödning av mykobakterier och visade potential för behandling av multiresistent tuberkulos. Formuleringen gav hög lokal läkemedelsretention och minimala systemiska biverkningar, vilket indikerar att lägre doser av CLZ kan administreras jämfört med nuvarande oral behandling, samtidigt som antimikrobiella koncentrationer i lungorna bibehålls.

I en andra studie visades hur MSP kan användas för att formulera proteiner, specifikt lysozym, som en torrpulverformulering. Aerosoliserings- och frisättningsprofiler undersöktes, och resultaten visade att proteinet deponerades i lungorna samtidigt som dess enzymatisk aktivitet bibehölls. Detta understryker MSP:s mångsidighet för denna typ av terapeutisk tillämpning.

MSP:s effekter på cellviabilitet och läkemedelsfrisättning undersöktes, särskilt om kiseldioxid med olika löslighetsegenskaper påverkar dessa faktorer. Alla typer av löslig kiseldioxid gav begränsade inflammatoriska reaktioner, vilket betonar potentialen och säkerheten hos amorf kiseldioxid för läkemedelsadministrering via lungorna.

En vidareutveckling under avhandlingsarbetet var designen av bioinspirerade lungytaktiva beläggningar på MSP, med målet att förbättra upplösningen av CLZ och underlätta transporten i slem och bronkialvävnad. Detta koncept förfinades ytterligare genom att belägga MSP med bakteriella lipider från mykobakterier, i syfte att undersöka ifall CLZ:s antimikrobiella aktivitet mot mykobakterier kunde förbättras, vilket skulle öppna för en ny strategi för behandling av lunginfektioner.

Sammanfattningsvis visar denna avhandling att bioinspirerade belagda MSP har potential som ett avancerat läkemedelsbärarsystem för att adressera hittills ouppfyllda behov i behandlingen av luftvägsinfektioner och hanteringen av antimikrobiell resistens.

Pulmonary delivery and formulation of biologics are among the more complex and growing scientific topics in drug delivery. We herein developed a dry powder formulation using disordered mesoporous silica particles (MSP) as the sole excipient and lysozyme, the most abundant antimicrobial proteins in the airways, as model protein. The MSP had the optimal size for lung deposition (2.43 ± 0.13 µm). A maximum lysozyme loading capacity (0.35 mg/mg) was achieved in 150 mM PBS, which was seven times greater than that in water. After washing and freeze-drying, we obtained a dry powder consisting of spherical, non-aggregated particles, free from residual buffer, or unabsorbed lysozyme. The presence of lysozyme was confirmed by TGA and FT-IR, while N₂ adsorption/desorption and SAXS analysis indicate that the protein is confined within the internal mesoporous structure. The dry powder exhibited excellent aerodynamic performance (fine particle fraction <5 µm of 70.32%). Lysozyme was released in simulated lung fluid in a sustained kinetics and maintaining high enzymatic activity (71–91%), whereas LYS-MSP were shown to degrade into aggregated nanoparticulate microstructures, reaching almost complete dissolution (93%) within 24 h. MSPs were nontoxic to in vitro lung epithelium. The study demonstrates disordered MSP as viable carriers to successfully deliver protein to the lungs, with high deposition and retained activity.

Inhalation therapy treating severe infectious disease is among the more complex and emerging topics in controlled drug release. Micron-sized carriers are needed to deposit drugs into the lower airways, while nano-sized carriers are of preference for cell targeting. Here, we present a novel and versatile strategy using micron-sized spherical particles with an excellent aerodynamic profile that dissolve in the lung fluid to ultimately generate nanoparticles enabling to enhance both extra- and intra-cellular drug delivery (i.e., dual micro-nano inhalation strategy). The spherical particles are synthesised through the condensation of nano-sized amorphous silicon dioxide resulting in high surface area, disordered mesoporous silica particles (MSPs) with monodispersed size of 2.43 μm. Clofazimine (CLZ), a drug shown to be effective against multidrug-resistant tuberculosis, was encapsulated in the MSPs obtaining a dry powder formulation with high respirable fraction (F.P.F. <5 μm of 50%) without the need of additional excipients. DSC, XRPD, and Nitrogen adsorption-desorption indicate that the drug was fully amorphous when confined in the nano-sized pores (9-10 nm) of the MSPs (shelf-life of 20 months at 4 °C). Once deposited in the lung, the CLZ-MSPs exhibited a dual action. Firstly, the nanoconfinement within the MSPs enabled a drastic dissolution enhancement of CLZ in simulated lung fluid (i.e., 16-fold higher than the free drug), increasing mycobacterial killing than CLZ alone (p = 0.0262) and reaching concentrations above the minimum bactericidal concentration (MBC) against biofilms of M. tuberculosis (i.e., targeting extracellular bacteria). The released CLZ permeated but was highly retained in a Calu-3 respiratory epithelium model, suggesting a high local drug concentration within the lung tissue minimizing risk for systemic side effects. Secondly, the micron-sized drug carriers spontaneously dissolve in simulated lung fluid into nano-sized drug carriers (shown by Nano-FTIR), delivering high CLZ cargo inside macrophages and drastically decreasing the mycobacterial burden inside macrophages (i.e., targeting intracellular bacteria). Safety studies showed neither measurable toxicity on macrophages nor Calu-3 cells, nor impaired epithelial integrity. The dissolved MSPs also did not show haemolytic effect on human erythrocytes. In a nutshell, this study presents a low-cost, stable and non-invasive dried powder formulation based on a dual micro-nano carrier to efficiently deliver drug to the lungs overcoming technological and practical challenges for global healthcare.