One‐Step Formulation of Protein Microparticles with Tailored Properties: Hard Templating at Soft Conditions

Formulation of therapeutic proteins into particulate forms is a main strategy for site‐specific and prolonged protein delivery as well as for protection against degradation. Precise control over protein particle size, dispersity, purity, as well as mild preparation conditions and minimal processing steps are highly desirable. It is, however, hard to fit all these criteria with conventional preparation techniques. Here a one‐step hard‐templating synthesis of microparticles composed of functional, non‐denatured protein is reported. The method is based on filling porous CaCO₃ microtemplates with the protein near to its isoelectric point (pI) followed by pH‐ or EDTA‐mediated dissolution of the tempplates. In principle, a wide variety of proteins can be converted into microparticles using this approach. The main requirement is an overlap of the protein insolubility and a template solubility for a certain parameter (here pH or EDTA). Here the formulation of insulin particles is studied in detail and it is shown that particles consisting of high molecular weight protein (catalase) can also be prepared. In this context, the synthesis of CaCO₃ templates with controlled size, the mechanism of the protein microparticle formation and mechanical properties of the microparticles are discussed. For the first time, the fabrication of mesoporous monodispersed CaCO₃ microtemplates with identical porocity but tuned diameter from 3 to 20 μm is demonstrated. The protein particle diameter can be adjusted by choosing the appropriate template size that is critical for successful pulmonary delivery of insulin. As a first step towards insulin delivery, the in vitro release of insulin at physiological conditions is studied.     

Monolayers of mono- and bipolar palmitic acid derivatives

Monopolar and bipolar derivatives of hexadecanoic acid (HA), 16-hydroxyhexadecanoic acid (HHA), methyl hexadecanoate (MH) and methyl 16-hydroxyhexadecanoate (MHH) have been investigated on pure water and NaCl solutions with different ion concentrations (1, 2 and 3 mol l⁻¹). Surface pressure area isotherms show that HA forms a fully condensed monolayer on pure water at 20 °C [E. Teer, C.M. Knobler, S. Siegel, D. Vollhardt, G. Brezesinski, J. Phys. Chem., B104, 43, 2000, pp. 10053–10058] whereas in the case of the corresponding bipolar HHA the hydroxy group as a second polar moiety leads to a destabilization of the monolayer. The presence of two relatively strong hydrophilic polar groups at opposite ends of the chain prevents the formation of condensed films. The esterification of the carboxyl group (MH) changes the phase sequence from L₂–Ov–LS for HA to L₂–LS. Inserting a hydroxy group at the end of the chain (MHH) shifts the liquid expanded/liquid condensed (LE/LC) phase transition to higher surface pressures but does not change the phase sequence, however it increases the chain tilt. The pressure of the first-order phase transition LE/LC is strongly temperature dependent for MH, while the transition pressure of MHH is almost temperature independent. The phase behavior of MHH and MH on pure water was further studied by surface potential, Brewster angle microscopy (BAM), fluorescence microscopy and grazing incidence X-ray diffraction (GIXD) measurements. The LC domains of MHH on pure water are so small that no inner texture can be observed by BAM in contrast to the LC domains of MH. 3M NaCl in the subphase does not change the MH textures, while it increases the size of the LC domains of MHH. The influence of the hydroxy group on the monolayer behavior is discussed in terms of the formation of hydrogen bonds. The presence of NaCl in the subphase expands the monolayers. The results obtained are explained by changes in monolayer–monolayer and monolayer–subphase interactions.     

Controlling the Microstructure of Monomolecular Layers

This review reports on the range of lateral structures which have been detected in ultrathin organic films using the newly-developed techniques of fluorescence microscopy and X-ray scattering, together with more conventional methods. A number of unusual low-dimensional ordering processes have been revealed. Hexagonal, lamellar or fractal domain structures are observed and shown to result from an interplay of electrostatic forces due to molecular alignment at interfaces, line energy between different phases and growth kinetics. On a molecular level the microstructure is distinguished by low coherence length of positional order but long coherence length concerning the orientation of crystallographic axes. It is demonstrated that the ideas presented are also relevant to adsorbate structures at interfaces and to the protein arrangement in monolayers.     

Elektrometrische Bestimmung der Hygiene-Hilfsparameter pH-Wert und Redox-Spannung

Ohne Zusammenfassung

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Electrometric determination of the hygiene auxiliary parameters pH-value and redox voltage

     

Hollow polymer shells from biological templates: fabrication and potential applications

Three-dimensional ultrathin polymer shells have been produced by a combination of step-by-step adsorption of polyelectrolytes on glutaraldehyde-treated human erythrocytes and subsequent solubilization of the cytoplasmatic constituents by means of a deproteinizing agent. The obtained hollow films preserve both the size and shape of the templating cells. This opens a pathway for the fabrication of polymeric capsules within a wide range of size and shape by using various biological templates. They may have exciting potential applications, such as templates for nanocomposites, as containers for a large class of materials, or as cages for chemical reactions. The thickness of the films can be adjusted over a large range: from a few nm up to several tens of nm. The polymer shells are permeable to small molecules and ions but not to macromolecules. An increase in the ionic strength of the solution up to 100 mmol make the capsules permeable for proteins. Permeability and conductivity studies have provided evidence that the adsorption of lipids on polyelectrolyte layers is a means of producing capsules with controlled permeability properties. 6-Carboxyfluorescein and Rhodamin 6G were precipitated within the capsules.     

Plasmonic films based on colloidal lithography

This paper reviews recent advances in the field of plasmonic films fabricated by colloidal lithography. Compared with conventional lithography techniques such as electron beam lithography and focused ion beam lithography, the unconventional colloidal lithography technique with advantages of low-cost and high-throughput has made the fabrication process more efficient, and moreover brought out novel films that show remarkable surface plasmon features. These plasmonic films include those with nanohole arrays, nanovoid arrays and nanoshell arrays with precisely controlled shapes, sizes, and spacing. Based on these novel nanostructures, optical and sensing performances can be greatly enhanced. The introduction of colloidal lithography provides not only efficient fabrication processes but also plasmonic films with unique nanostructures, which are difficult to be fabricated by conventional lithography techniques.     

Anisotropic multicompartment micro- and nano-capsules produced via embedding into biocompatible PLL/HA films

We present a novel strategy to fabricate anisotropic multicompartment Janus capsules by embedding larger containers into a soft poly-L-lysine/hyaluronic acid (PLL/HA) polymeric film, followed by adsorption of smaller containers on top of their unmasked surface. This research is also attractive for developing substrates for cell cultures.