Complex coacervation of food grade antimicrobial lauric arginate with lambda carrageenan.

In this study, the complex coacervation mechanism of Lauric arginate ester (LAE) with λ-carrageenan was studied using turbidimetry, light scattering and electrophoresis. The complexes formed were found to have a bilayer-like structure using small angle X-ray scattering (SAXS) and cryo-TEM (transmission electron microscopy). It was observed that mixing LAE with Sodium dodecyl sulfate (SDS) could significantly reduce the interactions between mixed micelles and λ-carrageenan. The interactions between LAE/SDS and λ-carrageenan were found to be predominantly entropy driven. Mixed micelles of LAE/Tween 20 and LAE/SDS showed significantly less interactions with carrageenan compared to pure LAE micelles. Interfacial properties of complexes were measured using surface tension measurements. It was observed that pure LAE showed good foaming behavior and when mixed with increasing amounts of carrageenan the foaming capacity decreased. Reduction in foam volume was due to reduced availability of free LAE molecules for foam stabilization and due to hydrophilic nature of complexes.

Immunoglobulins on the surface of differently charged polymer nanoparticles.

The overall success of nanocarriers in biomedical applications depends on their interaction with different proteins in blood. Immunoglobulins as a major protein class of the blood proteome may considerably influence the identity of the nanocarriers in blood. However, there is a lack of knowledge about the specific details of the interaction mechanism between different immunoglobulins and nanocarriers. Therefore, the authors have investigated the interaction of different immunoglobulin classes-namely, immunoglobulin G, A, and M-with different polystyrene model nanoparticles. The authors report that immunoglobulin interaction with nanoparticles strongly depends on the immunoglobulin class and surface charge of the nanoparticles. Furthermore, upon adsorption on the nanoparticles' surfaces, aggregation processes and denaturation of immunoglobulins were observed. This highlights the importance of nanocarriers' design in order to prevent unfavorable denaturation and adsorption processes of immunoglobulins on nanoparticle surfaces.

Controlling protein interactions in blood for effective liver immunosuppressive therapy by silica nanocapsules.

Immunosuppression with glucocorticoids is a common treatment for autoimmune liver diseases and after liver transplant, which is however associated with severe side-effects. Targeted delivery of glucocorticoids to inflammatory cells, e.g. liver macrophages and Kupffer cells, is a promising approach for minimizing side effects. Herein, we prepare core-shell silica nanocapsules (SiO2 NCs) via a sol-gel process confined in nanodroplets for targeted delivery of dexamethasone (DXM) for liver immunosuppressive therapy. DXM with concentrations up to 100 mg mL-1 in olive oil are encapsulated while encapsulation efficiency remains over 95% after 15 days. Internalization of NCs by non-parenchymal murine liver cells significantly reduces the release of inflammatory cytokines, indicating an effective suppression of inflammatory response of liver macrophages. Fluorescent and magnetic labeling of the NCs allows for monitoring their intracellular trafficking and biodegradation. Controlled interaction with blood proteins and good colloidal stability in blood plasma are achieved via PEGylation of the NCs. Specific proteins responsible for stealth effect, such as apolipoprotein A-I, apolipoprotein A-IV, and clusterin, are present in large amounts on the PEGylated NCs. In vivo biodistribution investigations prove an efficient accumulation of NCs in the liver, underlining the suitability of the SiO2 NCs as a dexamethasone carrier for treating inflammatory liver diseases.

Isothermal titration calorimetry as a complementary method for investigating nanoparticle-protein interactions.

Isothermal titration calorimetry (ITC) is a complementary technique that can be used for investigations of protein adsorption on nanomaterials, as it quantifies the thermodynamic parameters of intermolecular interactions in situ. As soon as nanomaterials enter biological media, a corona of proteins forms around the nanomaterials, which influences the surface properties and therefore the behavior of nanomaterials tremendously. ITC enhances our understanding of nanoparticle-protein interactions, as it provides information on binding affinity (in form of association constant Ka), interaction mechanism (in form of binding enthalpy ΔH, binding entropy ΔS and Gibbs free energy ΔG) and binding stoichiometry n. Therefore, as a complementary method, ITC enhances our mechanistic understanding of the protein corona. In this minireview, the information obtained from a multitude of ITC studies regarding different nanomaterials and proteins are gathered and relations between nanomaterials' properties and their resulting interactions undergone with proteins are deduced. Nanomaterials formed of a hydrophilic material without strongly charged surface and steric stabilization experience the weakest interactions with proteins. As a result, such nanomaterials undergo the least unspecific protein-interactions and are most promising for allowing an engineering of the protein corona.

Prevention of Dominant IgG Adsorption on Nanocarriers in IgG-Enriched Blood Plasma by Clusterin Precoating.

Nanocarriers for medical applications must work reliably within organisms, independent of the individual differences in the blood proteome. Variation in the blood proteome, such as immunoglobulin levels, is a result of environmental, nutrition, and constitution conditions. This variation, however, should not influence the behavior of nanocarriers in biological media. The composition of the protein corona is investigated to understand the influence varying immunoglobulin levels in the blood plasma have on the interactions with nanocarriers. Specifically, the composition of the nanocarriers' coronas is analyzed after incubation in plasma with normal or elevated immunoglobulin G (IgG) levels, and cellular uptake is monitored in cell lines containing different immunoglobulin receptors. Here, it is reported that upon doubling the IgG concentration in plasma, the IgG fraction in the protein corona increases by a factor of 40 independent of the nanocarrier material. This results in a significant increase in uptake in cells exhibiting IgG binding receptors. Furthermore, precoating nanocarriers with clusterin successfully prevents dominant IgG-adsorption and additionally reduces cellular internalization, after incubation with IgG-enriched plasma. Therefore, precoating nanocarriers may be utilized as a powerful method to reduce the influence of individual variations in blood composition on the protein corona.

Beyond the protein corona - lipids matter for biological response of nanocarriers.

The interaction of nanocarriers with blood plasma components influences the biological response, and therefore, it needs to be controlled. Whereas protein adsorption to nanocarriers has been investigated to a large extent, the role of lipid interaction for drug delivery and its biological effect is not yet clear. However, lipids represent an important constituent of blood plasma and are usually bound in the form of lipoproteins. Because already for many nanocarrier systems an enrichment of apolipoproteins in their protein corona was reported, we examine the interaction of lipoproteins with nanocarriers. If interaction occurs in terms of lipoprotein adsorption, two scenarios are possible: adsorption of intact lipoprotein complexes or disintegration of the complexes with adsorption of the single components. To investigate the interaction and clarify which scenario occurs, polymeric model nanoparticles and different lipoprotein types have been studied by isothermal titration calorimetry, transmission electron microscopy, and other methods. Our data indicate that upon contact with polymeric nanoparticles, disintegration of lipoproteins and adsorption of lipids occurs. Further, the effect of lipoprotein adsorption on cell uptake has been examined, and a major effect of the lipoproteins has been found. STATEMENT OF SIGNIFICANCE: It is now well accepted that nanomaterials developed as diagnostic or therapeutic carrier systems need to be well characterized in terms of biological responses inside an organism. Many studies have already shown that proteins adsorb to the surface of a nanomaterial and create a new interface that define the identity of the material. However, the presence of other surface-active components of the blood plasma and how they interact with nanomaterials has been much less investigated. Thus, this study aims at providing a significant contribution to understanding the interaction mechanism between lipoproteins and nanomaterials. Since lipoproteins transport a high amount of lipids, which are surface-active molecules, the demonstrated interactions can go as far as complete lipoprotein disintegration.

Reliable and Easy-To-Use Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Analysis of Fluconazole, Isavuconazole, Itraconazole, Hydroxy-Itraconazole, Posaconazole, and Voriconazole in Human Plasma and Serum.

BACKGROUND: A fast and easy-to-use liquid chromatography-tandem mass spectrometry method for the determination and quantification of 6 triazoles [fluconazole (FLZ), isavuconazole (ISZ), itraconazole (ITZ), hydroxy-itraconazole (OH-ITZ), posaconazole (PSZ), and voriconazole (VRZ)] in human plasma and serum was developed and validated for therapeutic drug monitoring. METHODS: Sample preparation was based on protein precipitation with acetonitrile and subsequent centrifugation. Isotope-labeled analogues for each analyte were used as internal standards. Chromatographic separation was achieved using a 50 × 2.1 mm, 1.9 µm polar Hypersil Gold C18 column and mobile phase consisting of 0.1% formic acid/acetonitrile (45%/55%, vol/vol) at a flow rate of 340 µL/min. The triazoles were simultaneously detected using a triple-stage quadrupole mass spectrometer operated in selected reaction monitoring mode with positive heated electrospray ionization within a single runtime of t = 3.00 minutes. RESULTS: Linearity of all azole concentration ranges was verified by the Mandel test and demonstrated for all azoles. All calibration curves were linear and fitted using least squares regression with a weighting factor of the reciprocal concentration. Limits of detection (µg/L/L) were FLZ, 9.3; ISZ, 0.3; ITZ, 0.6; OH-ITZ, 8.6; PSZ, 3.4; and VRZ, 2.1. The lower limits of quantitation (µg/L/liter) were FLZ, 28.3; ISZ, 1.0; ITZ, 1.7; OH-ITZ, 26.2; PSZ, 10.3; and VRZ, 6.3. Intraday and interday precisions ranged from 0.6% to 6.6% for all azoles. Intraday and interday accuracies (%bias) of all analytes were within 10.5%. In addition, we report on a 29-year-old white woman (94 kg body weight) with a history of acute myeloid leukemia who underwent stem cell transplantation. Because of diagnosis of aspergillus pneumonia, antifungal pharmacotherapy was initiated with different application modes and dosages of ISZ, and plasma concentrations were monitored over a time period of 6 months. CONCLUSIONS: A precise and highly sensitive liquid chromatography-tandem mass spectrometry method was developed that enables quantification of triazoles in plasma and serum matrix across therapeutically relevant concentration ranges. It was successfully implemented in our therapeutic drug monitoring routine service and is suitable for routine monitoring of antifungal therapy and in severely ill patients.