RBD-Based ELISA and Luminex Predict Anti-SARS-CoV-2 Surrogate-Neutralizing Activity in Two Longitudinal Cohorts of German and Spanish Health Care Workers.

The ability of antibodies to neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important correlate of protection. For routine evaluation of protection, however, a simple and cost-efficient anti-SARS-CoV-2 serological assay predictive of serum neutralizing activity is needed. We analyzed clinical epidemiological data and blood samples from two cohorts of health care workers in Barcelona and Munich to compare several immunological readouts for evaluating antibody levels that could be surrogates of neutralizing activity.

Predictive Shapes of Ellipsoid PPDL-PTHF Copolymer Particles Prepared by the Phantom Stretching Technique.

Ellipsoidal polymer particles can be prepared from spheres by unidirectional stretching at elevated temperatures, while the particles' aspect ratios () that result from this phantom stretching methodology are often not precisely predictable. Here, an elastic deformation model was exemplarily evaluated for ~50 µm spherical microparticles from PPDL-PTHF block copolymers. The prolate ellipsoidal particles, obtained by stretching in polyvinyl alcohol phantoms, differed in dimensions at identical relative phantoms elongations up to 150%, depending on the relative polymer composition and their systematically altered mechanical properties.

In Situ X-Ray Scattering Studies of Poly(ε-caprolactone) Networks with Grafted Poly(ethylene glycol) Chains to Investigate Structural Changes during Dual- and Triple-Shape Effect.

The dual- and triple-shape effects of multiphase polymer networks that contain two crystallizable chain segments have been assessed in situ by combining X-ray measurements with thermomechanical investigations. The studied polymer, named CLEG, is a multiphase polymer network of crystallizable poly(ε-caprolactone) (PCL) with grafted poly(ethylene glycol) (PEG) side chains. Wide-angle (WAXS) and small-angle X-ray scattering (SAXS) measurements were combined with temperature-controlled in situ tensile testing experiments.

Knowledge-based tailoring of gelatin-based materials by functionalization with tyrosine-derived groups.

Molecular models of gelatin-based materials formed the basis for the knowledge-based design of a physically cross-linked polymer system. The computational models with 25 wt.-% water content were validated by comparison of the calculated structural properties with experimental data and were then used as predictive tools to study chain organization, cross-link formation, and estimation of mechanical properties.

Current status of Langmuir monolayer degradation of polymeric biomaterials.

Langmuir monolayer degradation (LMD) experiments with polymers possessing outstanding biomedical application potential yield information regarding the kinetics of their hydrolytic or enzymatic chain scission under well-defined and adjustable degradation conditions. A brief review is given of LMD investigations, including the author's own work on 2-dimensional (2D) polymer systems, providing chain scission data, which are not disturbed by simultaneously occurring transport phenomena, such as water penetration into the sample or transport of scission fragments out of the sample. A knowledge-based approach for the description and simulation of polymer hydrolytic and enzymatic degradation based on a combination of fast LMD experiments and computer simulation of the water penetration is briefly introduced.

A molecular dynamic analysis of gelatin as an amorphous material: prediction of mechanical properties of gelatin systems.

Biomaterials are used in regenerative medicine for induced autoregeneration and tissue engineering. This is often challenging, however, due to difficulties in tailoring and controlling the respective material properties. Since functionalization is expected to offer better control, in this study gelatin chains were modified with physically interacting groups based on tyrosine with the aim of causing the formation of physical crosslinks.

Knowledge-based approach towards hydrolytic degradation of polymer-based biomaterials.

The concept of hydrolytically degradable biomaterials was developed to enable the design of temporary implants that substitute or fulfill a certain function as long as required to support (wound) healing processes or to control the release of drugs. Examples are surgical implants, e.g.

Membrane association and selectivity of the antimicrobial peptide NK-2: a molecular dynamics simulation study.

In an effort to better understand the initial mechanism of selectivity and membrane association of the synthetic antimicrobial peptide NK-2, we have applied molecular dynamics simulation techniques to elucidate the interaction of the peptide with the membrane interfaces. A homogeneous dipalmitoylphosphatidylglycerol (DPPG) and a homogeneous dipalmitoylphosphatidylethanolamine (DPPE) bilayers were taken as model systems for the cytoplasmic bacterial and human erythrocyte membranes, respectively. The results of our simulations on DPPG and DPPE model membranes in the gel phase show that the binding of the peptide, which is considerably stronger for the negatively charged DPPG lipid bilayer than for the zwitterionic DPPE, is mostly governed by electrostatic interactions between negatively charged residues in the membrane and positively charged residues in the peptide.

A generalized direct-particle-deletion scheme for the calculation of chemical potential and solubilities of small- and medium-sized molecules in amorphous polymers.

The development, validation, and first applications of a generalized version of an inverse Widom method are described. It permits the calculation of solubility coefficients for molecules as large as, e.g.