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Superparamagnetic iron oxide nanoparticles (SPIONs) exhibit unique properties for diverse biomedical applications, including drug delivery and diagnostic imaging. Actively targeted SPIONs enhance delivery to diseased sites, reducing side effects and enhancing treatment efficacy. However, development of reproducible functionalization protocols is challenged by the erratic behavior of nanoparticles in suspensions, such as agglomeration and sedimentation. In this study, we develop and systematically optimize a functionalization method to attach the Fc-region of antibodies onto silica coated SPIONs via click chemistry, ensuring controlled ligand orientation on the particle surface. The synthesis and successive modifications of silica coated SPIONs with organic moieties is presented resulting in the final click conjugation with anti-ICAM1 antibodies. These antibodies target ICAM1, upregulated on epithelial cell surfaces during gastrointestinal inflammation. Thermogravimetric analysis and infrared spectroscopy confirm successful SPION functionalization after each modification step. Cell viability assessment indicates no adverse effects of bioconjugated particles. Quantitative elemental analysis reveals significantly higher iron concentration in inflammation-induced Caco-2 cells exposed to ICAM1-modified particles compared to non-conjugated counterparts. Furthermore, laser scanning confocal microscopy of these cells suggests surface interaction and internalization of bioconjugated SPIONs, underscoring their potential for targeted imaging and therapy in inflammatory diseases.

Magnetic particle imaging (MPI) is an emerging imaging modality that shows potential in tumor imaging, cell tracking, and angiography. It uses the signal generated from superparamagnetic iron oxide nanoparticles (SPIONs) with zero attenuation in tissue, showing excellent sensitivity and contrast. MPI resolution and sensitivity are dependent on the nonlinear dynamic magnetization of the SPION tracer and can be improved by tuning their magnetic properties. Doping SPIONs with manganese or zinc is an effective and biocompatible route to modify the magnetic properties of SPIONs. This study developed SPIONs doped with manganese or zinc as MPI tracers using flame spray pyrolysis (FSP), a highly scalable synthesis technique. The MPI performance was evaluated with a MOMENTUM imager. Postsynthesis citrate coating and filtration significantly enhanced the MPI resolution of SPIONs. The Zn-doped SPIONs exhibited the best resolution, while Mn-doped SPIONs showed the highest sensitivity. The overall MPI performance of all tracers was closely linked to their magnetic diameter and susceptibility, but deviated noticeably from the predictions of the Langevin model. Zn-doped SPIONs were encapsulated in a water-dispersible nanocarrier using flash nanoprecipitation (FNP), circumventing the need for citrate coating while preserving MPI performance. These findings show that the hydrodynamic size, size distribution, and composition of the SPIONs are critical to MPI performance and highlight the potential of combining FSP and FNP for large-scale production of the MPI tracers.

Magnetic hyperthermia therapy using superparamagnetic iron oxide nanoparticles (SPIONs) offers a promising strategy for treating cancers resistant to chemo- and radiotherapy. However, oral delivery of SPIONs for localized treatment of gastrointestinal cancers has not been widely explored. Here, we report the development of methoxy polyethylene glycol (mPEG) functionalized SPIONs (mPEG-Mn_0.6Zn_0.4Fe₂O₄) engineered for oral administration with combined theranostic functionalities for magnetic hyperthermia treatment and magnetic resonance imaging (MRI) in colorectal cancer (CRC). The SPIONs achieved consistent heating performance in biorelevant colonic environments, exceeding a 5°C temperature increase within 10 min under an alternating magnetic field (AMF). They also demonstrated superior r₂ relaxivity compared to γ-Fe₂O₃, highlighting their potential as effective T₂ MRI contrast agents. In vitro studies using CRC SW480 and Caco-2 cell lines assessed nanoparticle cytotoxicity, cellular uptake, and magnetic hyperthermia efficacy in both upright and inverted cell culture configurations. Magnetic hyperthermia induced significant CRC cell death in vitro, particularly in upright configurations, attributed to enhanced localized heating caused by nanoparticle sedimentation and enhanced SPION contact with cell surfaces. This emphasizes the importance of in vitro experimental parameters such as cell line, configuration, and AMF exposure time for systematic optimization of theranostic SPIONs during preclinical development. Finally, in vivo studies using a colorectal tumor xenograft mouse model demonstrated a marked therapeutic effect of magnetic hyperthermia by intratumorally injected SPIONs. The tumor volume was reduced by 63% following a single 20-minute AMF exposure. These findings demonstrate the potential of mPEG-Mn_0.6Zn_0.4Fe₂O₄ nanoparticles as a promising platform for non-invasive, image-guided magnetic hyperthermia therapy in CRC theranostics.

Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global healthcare challenge, causing a range of life-threatening infections, including osteomyelitis, septic arthritis, skin and soft tissue infections, and wound infections. These infections are difficult to treat, often requiring aggressive therapeutic strategies at high antibiotic doses that increase the risk of adverse effects and drive the development of antimicrobial resistance. An alternative strategy to enhance antibiotic efficacy involves the use of locally elevated temperatures to increase the bacterial susceptibility to drugs. This can be achieved non-invasively, using magnetic hyperthermia induced by superparamagnetic iron oxide nanoparticles (SPIONs) in an alternating magnetic field (AMF). This study, presents a synergistic platform combining magnetic hyperthermia and antibiotic therapy to combat MRSA infections. Magnetic microfibers were fabricated by electrospinning using poly(methyl methacrylate) and tributyl citrate, incorporating functional Mn0.25Fe2.75O4 nanoparticles. The microfibers were systematically optimized to attain necessary tensile strength and heating efficiency for localized treatment of MRSA. Upon AMF exposure, the SPION-loaded microfiber discs achieved tunable temperatures exceeding 60 degrees C, controlled by varying the microfiber disc weight. The combination of doxycycline and magnetic hyperthermia exposure for 15 min demonstrated significant synergistic effects against MRSA at temperatures above 50 degrees C. In vitro, the antibiotic efficacy of doxycycline was enhanced by up to 35 % against MRSA, even at sub-inhibitory drug doses. The use of biocompatible materials in magnetic microfibers makes them well suited for localized therapy, particularly for treating wound infections. Additionally, the synergistic combination of magnetic hyperthermia with antibiotic therapy could enable lower drug doses, reducing the antibiotic burden and helping to combat antimicrobial resistance.

Development of oral drug delivery systems that penetrate the colonic mucus remains challenging. Artificial models of porcine colonic mucus have been developed that mimic the rheology and viscosity of the native mucus and its contents of mucins, protein, and lipids. However, they are less representative with regard to the zeta potential, a factor of importance for charged molecules and particles. This study therefore aimed to improve the existing porcine artificial colonic mucus model by exchanging the polymer backbone (used for viscosity) to more closely mimic the charge of porcine native colonic mucus. Polymers studied were poly(acrylic acid), hydroxyethylcellulose, sodium hyaluronate, sodium alginate, and pectin. The resulting porcine artificial colonic mucus was assayed for apparent viscosity, storage modulus, pH, water content, zeta potential, and pore size. The two best-performing polymers (poly(acrylic acid) and hydroxyethylcellulose) were then assayed with diffusion of FITC-dextran, particle tracking of nanoparticles, and binding of FITC-dextran and contrasted to data generated in porcine native colonic mucus (PNCM). Of the two polymers, PACM based on HEC generated zeta potential and binding kinetics similar to those of PNCM. We conclude that the choice of polymer in PACMs is critical for improving their use in drug development. The extensive characterization of the PACMs further points toward the importance of complementary techniques to determine rheological characteristics, mesh, and pore size.

Permeapad® is an artificial biomimetic barrier for in vitro permeation experiments, which has an intricate nano- and microstructure consisting of two cellulose hydrate sheets enclosing a layer of phospholipids forming multiple, multilamellar vesicles in contact with the assay medium. Due to this structure, transport across this barrier can be regarded as complex deserving further attention. Until now, only Permeapad® with phosphatidylcholine, the most abundant phospholipid in cell membranes, has been described in literature. However, from biological systems and other artificial barriers, it is known that permeation properties can vary with phospholipid composition. This study presents a combination of experimental and computational techniques to study and explain the transport of molecules across the Permeapad® barrier. For this, we investigated Permeapad® variants with other phospholipid compositions including phosphatidylethanolamine, the second most abundant phospholipid in cell membranes, and phosphatidylglycerol, representing a phospholipid with a negatively charged headgroup by measuring the permeability of three drugs, metoprolol (a weak base), naproxen (a weak acid) and hydrocortisone (a non-ionizable drug). Phospholipid composition only affected the permeability of metoprolol significantly. We used molecular dynamics simulations to understand the underlying mechanisms of the permeability differences extracting several descriptors of membrane properties and predicting permeability. Surprisingly, an almost inverse relationship between experimental and computational permeability was observed. Permeapad®'s highly compartmentalized structure was hypothesized to cause this observation. This study offers a deeper understanding of the functionality of the Permeapad® barrier.

Chronic inflammatory conditions are among the most prevalent diseases worldwide. Several debilitating diseases such as atherosclerosis, inflammatory bowel disease, rheumatoid arthritis, and Alzheimer's are linked to chronic inflammation. These conditions often develop into complex and fatal conditions, making early detection and treatment of chronic inflammation crucial. Current diagnostic methods show high variability and do not account for disease heterogeneity and disease-specific proinflammatory markers, often delaying the disease detection until later stages. Furthermore, existing treatment strategies, including high-dose anti-inflammatory and immunosuppressive drugs, have significant side effects and an increased risk of infections. In recent years, superparamagnetic iron oxide nanoparticles (SPIONs) have shown tremendous biomedical potential. SPIONs can function as imaging modalities for magnetic resonance imaging, and as therapeutic agents due to their magnetic hyperthermia capability. Furthermore, the surface functionalization of SPIONs allows the detection of specific disease biomarkers and targeted drug delivery. This systematic review explores the utility of SPIONs against chronic inflammatory disorders, focusing on their dual role as diagnostic and therapeutic agents. We extracted studies indexed in the Web of Science database from the last 10 years (2013–2023), and applied systematic inclusion criteria. This resulted in a final selection of 38 articles, which were analyzed for nanoparticle characteristics, targeted diseases, in vivo and in vitro models used, and the efficacy of the therapeutic or diagnostic modalities. The results revealed that ultrasmall SPIONs are excellent for imaging arterial and neuronal inflammation. Furthermore, novel therapies using SPIONs loaded with chemotherapeutic drugs show promise in the treatment of inflammatory diseases.

Magnetic hyperthermia holds significant therapeutic potential, yet its clinical adoption faces challenges. One obstacle is the large-scale synthesis of high-quality superparamagnetic iron oxide nanoparticles (SPIONs) required for inducing hyperthermia. Robust and scalable manufacturing would ensure control over the key quality attributes of SPIONs, and facilitate clinical translation and regulatory approval. Therefore, we implemented a risk-based pharmaceutical quality by design (QbD) approach for SPION production using flame spray pyrolysis (FSP), a scalable technique with excellent batch-to-batch consistency. A design of experiments method enabled precise size control during manufacturing. Subsequent modeling linked the SPION size (6–30 nm) and composition to intrinsic loss power (ILP), a measure of hyperthermia performance. FSP successfully fine-tuned the SPION composition with dopants (Zn, Mn, Mg), at various concentrations. Hyperthermia performance showed a strong nonlinear relationship with SPION size and composition. Moreover, the ILP demonstrated a stronger correlation to coercivity and remanence than to the saturation magnetization of SPIONs. The optimal operating space identified the midsized (15–18 nm) Mn_0.25Fe_2.75O₄ as the most promising nanoparticle for hyperthermia. The production of these nanoparticles on a pilot scale showed the feasibility of large-scale manufacturing, and cytotoxicity investigations in multiple cell lines confirmed their biocompatibility. In vitro hyperthermia studies with Caco-2 cells revealed that Mn_0.25Fe_2.75O₄ nanoparticles induced 80% greater cell death than undoped SPIONs. The systematic QbD approach developed here incorporates process robustness, scalability, and predictability, thus, supporting the clinical translation of high-performance SPIONs for magnetic hyperthermia.

Lipid-based formulations (LBFs) are used by the pharmaceutical industry in oral delivery systems for both poorly water-soluble drugs and biologics. Digestibility is key for the performance of LBFs and in vitro lipolysis is commonly used to compare the digestibility of LBFs. Results from in vitro lipolysis experiments depend highly on the experimental conditions and formulation characteristics, such as droplet size (which defines the surface area available for digestion) and interfacial structure. This study introduced the intrinsic lipolysis rate (ILR) as a surface area-independent approach to compare lipid digestibility. Pure acylglycerol nanoemulsions, stabilized with polysorbate 80 at low concentration, were formulated and digested according to a standardized pH–stat lipolysis protocol. A methodology originally developed to calculate the intrinsic dissolution rate of poorly water-soluble drugs was adapted for the rapid calculation of ILR from lipolysis data. The impact of surfactant concentration on the apparent lipolysis rate and lipid structure on ILR was systematically investigated. The surfactant polysorbate 80 inhibited lipolysis of tricaprylin nanoemulsions in a concentration-dependent manner. Coarse-grained molecular dynamics simulations supported these experimental observations. In the absence of bile and phospholipids, tricaprylin was shielded from lipase at 0.25% polysorbate 80. In contrast, the inclusion of bile salt and phospholipid increased the surfactant-free area and improved the colloidal presentation of the lipids to the enzyme, especially at 0.125% polysorbate 80. At a constant and low surfactant content, acylglycerol digestibility increased with decreasing acyl chain length, decreased esterification, and increasing unsaturation. The calculated ILR of pure acylglycerols was successfully used to accurately predict the IRL of binary lipid mixtures. The ILR measurements hold great promise as an efficient method supporting pharmaceutical formulation scientists in the design of LBFs with specific digestion profiles.