Grit Baier

Protein Corona of Nanoparticles: Distinct Proteins Regulate the Cellular Uptake

Understanding nanoparticle-protein interactions is a crucial issue in the development of targeted nanomaterial delivery. Besides unraveling the composition of the nanoparticles protein coronas, distinct proteins thereof could control nanoparticle uptake into specific cell types. Here we differentially analyzed the protein corona composition on four polymeric differently functionalized nanoparticles by label-free quantitative mass spectrometry. Next, we correlated the relative abundance of identified proteins in the corona with enhanced or decreased cellular uptake of nanoparticles into human cancer and bone marrow stem cells to identify key candidates. Finally, we verified these candidate proteins by artificially decorating nanoparticles with individual proteins showing that nanoparticles precoated with the apolipoproteins ApoA4 or ApoC3 significantly decreased the cellular uptake, whereas precoating with ApoH increased the cellular uptake.

BSA Adsorption on Differently Charged Polystyrene Nanoparticles using Isothermal Titration Calorimetry and the Influence on Cellular Uptake

BSA adsorption onto negatively and positively charged polystyrene nanoparticles was investigated. The nanoparticles were characterized in terms of particle size, zeta potential, surface group density, and morphology. The adsorption behavior of BSA on the particle surface, as a function of pH and overall charge of the particle, was studied using ITC. Different thermodynamic data such as enthalpy changes upon binding and stoichiometry of the systems were determined and discussed. The degree of surface coverage with BSA was calculated using the thermodynamic data. The cellular uptake of particles before and after BSA adsorption was studied using HeLa cells in the presence and absence of supplemented FCS in the cell culture medium.

Enzyme responsive hyaluronic acid nanocapsules containing polyhexanide and their exposure to bacteria to prevent infection.

Antibacterial nanodevices could bring coatings of plastic materials and wound dressings a big step forward if the release of the antibacterial agents could be triggered by the presence of the bacteria themselves. Here, we show that novel hyaluronic acid (HA)-based nanocapsules containing the antimicrobial agent polyhexanide are specifically cleaved in the presence of hyaluronidase, a factor of pathogenicity and invasion for bacteria like Staphylococcus aureus and Escherichia coli. This resulted in an efficient killing of the pathogenic bacteria by the antimicrobial agent. The formation of different polymeric nanocapsules was achieved through a polyaddition reaction in inverse miniemulsion. After the synthesis, the nanocapsules were transferred to an aqueous medium and investigated in terms of size, size distribution, functionality, and morphology using dynamic light scattering, zeta potential measurements and scanning electron microscopy. The enzyme triggered release of a model dye and the antimicrobial polyhexanide was monitored using fluorescence and UV spectroscopy. The stability of the nanocapsules in several biological media was tested and the interaction of nanocapsules with human serum protein was studied using isothermal titration calorimetry. The antibacterial effectiveness is demonstrated by determination of the antibacterial activity and determination of the minimal bactericidal concentration (MBC).

Cross-Linked Starch Capsules Containing dsDNA Prepared in Inverse Miniemulsion as "Nanoreactors" for Polymerase Chain Reaction

Cross-linked potato starch nanocapsules with encapsulated dsDNA (with a defined number of base pairs, i.e., 286, 476, and 790 bp) were synthesized using the miniemulsion technique. The inverse (water-in-oil) miniemulsion system was applied to create stable aqueous nanodroplets of dissolved starch in cyclohexane as a continuous phase. The amphiphilic block copolymer poly[(ethylene-co-butylene)-b-(ethylene oxide)] was used as a surfactant to stabilize the droplets. After addition of the cross-linker, 2,4-toluene diisocyanate (TDI), the polyaddition reaction took place at the droplets interface, resulting in the formation of a polymeric cross-linked shell. The influence of starch, surfactant, and the amount of cross-linker on the average size, size distribution, and morphology of the capsules was studied by dynamic light scattering and electron microscopy. FTIR spectroscopy was used to identify the chemical composition of the capsule shell. The permeability of the shell was studied on the fluorescent dye (i.e., sulforhodamine 101) containing capsules using fluorescence spectroscopy. High thermal stability of the cross-linked capsules allows one to perform the polymerase chain reaction inside the core. The encapsulation of dsDNA and the efficiency of the PCR were confirmed by fluorescence spectroscopy after staining with the DNA-selective dye (SYBRGreen).

Biodegradable lignin nanocontainers

The abundant biomaterial lignin was used to prepare hollow nanocapsules by interfacial polyaddition in inverse miniemulsions. These cross-linked lignin nanocontainers can be loaded with hydrophilic substances which can be released by an enzymatic trigger from natural plant extracts revealing them as potential nanocontainers for agricultural applications.

Aggregation Behavior of Polystyrene-Nanoparticles in Human Blood Serum and its Impact on the in vivo Distribution in Mice

The interactions between nanoparticles (NPs) and proteins in complex biological application media such as blood serum are capable of inducing aggregate formation which can lead to subsequent changes in biological activity. Here, we correlate surface charge, aggregation-tendency, and surface serum protein adsorption with cellular uptake and biodistribution in mice. Polystyrene-based NPs (80 - 170 nm) with different surface functionalizations were synthesized and incubated with human serum. Interaction of NPs with serum proteins and aggregate formation were analyzed by mass spectrometryanalysis and dynamic light-scattering. Influence of surface functionalization on specific cellular uptake and organdistribution was characterized. Localization and organ targeting of intravenously applied NPs preferentially depended on their aggregationbehavior in the presence of serum. Whereas strongly aggregating particles mainly located to liver, non-aggregating particles distributed to all organs. Determination of aggregate formation of NPs in the presence of serum and further analysis of the protein corona allows for pre-selection of NPs for in vivo application.

Nanocapsules for drug delivery through the skin barrier by tissue-tolerable plasma

For many years, several attempts have been made to enhance skin penetration by chemical, physical or mechanical manipulation to reduce the barrier function of the skin. The present study demonstrates the possibility of penetration enhancement for 400 nm sized nanocapsules loaded with a model drug consisting of a fluorescent dye by the application of tissue-tolerable plasma (TTP). Therefore, the stability of the nanocapsules and their penetration through the skin barrier prior to and in combination with TTP application was evaluated. The results revealed that the penetration of the nanocapsules could be effectively enhanced when applied in combination with TTP, hence delivering the model drug unaffected by plasma into deeper skin layers. The stability testing showed no significant structural changes of the nanocapsules after contact with TTP. Thus, the present study introduces a new strategy for the penetration enhancement of substances by the combined utilization of nanocapsules and TTP.

Nanocapsules generated out of a polymeric dexamethasone shell suppress the inflammatory response of liver macrophages

UNLABELLED Dexamethasone (DXM) is a synthetic glucocorticoid with anti-inflammatory properties. Targeted delivery of dexamethasone to inflammatory cells, e.g. macrophages and Kupffer cells represents a promising approach to minimize side effects. The aim of the present study was to induce a targeted transport of novel DXM-based biodegradable nanocapsules to phagocytic cells. Nanocapsules (NCs) consisting of a hydroxyethylated glucose polymer (hydroxyethyl starch, HES) shell with encapsulated DXM and NCs synthesized exclusively in inverse miniemulsion out of DXM were investigated. Non-parenchymal murine liver cells served as target cells. HES-DXM NCs were predominantly incorporated by Kupffer cells (KCs). In contrast, DXM NCs were phagocytized by KCs and endothelial cells. The release of the NC-content was confirmed by incorporation of CellTracker™ into the NCs. Uptake of DXM NCs by Kupffer cells reduced significantly the release of inflammatory cytokines in response to LPS stimulation. Importantly, the DXM NCs consisting exclusively out of a dexamethasone shell offer the potential to serve as carriers for additional therapeutics. FROM THE CLINICAL EDITOR In this paper, nanocapsule-based targeted delivery of dexamethasone to inflammatory cells is presented as a promising approach to minimize side effects and increase efficacy of this anti-inflammatory clinically used corticosteroid.

Functionalized Polystyrene Nanoparticles Trigger Human Dendritic Cell Maturation Resulting in Enhanced CD4+T Cell Activation

Nanoparticles (NP) represent a promising tool for biomedical applications. Here, sulfonate- and phosphonate-functionalized polystyrene NP are analyzed for their interaction with human monocyte-derived dendritic cells (DC). Immature dendritic cells (iDC) display a higher time- and dose-dependent uptake of functionalized polystyrene NP compared to mature dendritic cells (mDC). Notably, NP induce an enhanced maturation of iDC but not of mDC (upregulation of stimulatory molecules and cytokines). NP-triggered maturation results in a significantly enhanced T cell stimulatory capacity (increased CD4(+) T cell proliferation and IFN-γ production), indicating a shift to a pronounced Th1 response. Immunomodulatory properties of NP may be a useful strategy for strengthening the efficacy of NP-based approaches in immunotherapy.

Interleukin-2 Functionalized Nanocapsules for T Cell-Based Immunotherapy

A major demand on immunotherapy is the direct interference with specific immune cells in vivo. In contrast to antibody-engineered nanoparticles to control dendritic cells function, targeting of T cells for biomedical applications still remains an obstacle as they disclose reduced endocytic activities. Here, by coupling the cytokine interleukin-2 (IL-2) to the surface of hydroxyethyl starch nanocapsules, we demonstrated a direct and specifc T cell targeting in vitro and in vivo by IL-2 receptor-mediated internalization. For this purpose, defined amounts of azide-functionalized IL-2 were linked to alkyne-functionalized hydroxyethyl starch nanocapsules via copper-free click reactions. In combination with validated quantification of the surface-linked IL-2 with anthracen azide, this method allowed for engineering IL-2-functionalized nanocapsules for an efficient targeting of human and murine T cell populations with various IL-2 receptor affinities. This nanocapsule-mediated technique is a promising strategy for T cell-based immunotherapies and may be translated to other cytokine-related targeting systems.