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- ItemPolyelectrolyte complex nanoparticles of poly(ethyleneimine) and poly(acrylic acid): Preparation and applications(Basel : MDPI AG, 2011) Müller, M.; Keßler, B.; Fröhlich, J.; Poeschla, S.; Torger, B.In this contribution we outline polyelectrolyte (PEL) complex (PEC) nanoparticles, prepared by mixing solutions of the low cost PEL components poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAC). It was found, that the size and internal structure of PEI/PAC particles can be regulated by process, media and structural parameters. Especially, mixing order, mixing ratio, PEL concentration, pH and molecular weight, were found to be sensible parameters to regulate the size (diameter) of spherical PEI/PAC nanoparticles, in the range between 80-1,000 nm, in a defined way. Finally, applications of dispersed PEI/PAC particles as additives for the paper making process, as well as for drug delivery, are outlined. PEI/PAC nanoparticles mixed directly on model cellulose film showed a higher adsorption level applying the mixing order 1. PAC 2. PEI compared to 1. PEI 2. PAC. Surface bound PEI/PAC nanoparticles were found to release a model drug compound and to stay immobilized due to the contact with the aqueous release medium.
- ItemA thrombin-triggered self-regulating anticoagulant strategy combined with anti-inflammatory capacity for blood-contacting implants(Washington, DC [u.a.] : Assoc., 2022) Wang, Yanan; Wu, Haoshuang; Zhou, Zhongyi; Maitz, Manfred F.; Liu, Kunpeng; Zhang, Bo; Yang, Li; Luo, Rifang; Wang, YunbingInterrelated coagulation and inflammation are impediments to endothelialization, a prerequisite for the longterm function of cardiovascular materials. Here, we proposed a self-regulating anticoagulant coating strategy combined with anti-inflammatory capacity, which consisted of thrombin-responsive nanogels with anticoagulant and anti-inflammatory components. As an anticoagulant, rivaroxaban was encapsulated in nanogels cross-linked by thrombin-cleavable peptide and released upon the trigger of environmental thrombin, blocking the further coagulation cascade. The superoxide dismutase mimetic Tempol imparted the antioxidant property. Polyphenol epigallocatechin gallate (EGCG), in addition to its anti-inflammatory function in synergy with Tempol, also acted as a weak cross-linker to stabilize the coating. The effectiveness and versatility of this coating were validated using two typical cardiovascular devices as models, biological valves and vascular stents. It was demonstrated that the coating worked as a precise strategy to resist coagulation and inflammation, escorted reendothelialization on the cardiovascular devices, and provided a new perspective for designing endothelium-like functional coatings.
- ItemA stochastic weighted particle method for coagulation-advection problems(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Patterson, Robert I.A.; Wagner, WolfgangA spatially resolved stochastic weighted particle method for inception--coagulation--advection problems is presented. Convergence to a deterministic limit is briefly studied. Numerical experiments are carried out for two problems with very different coagulation kernels. These tests show the method to be robust and confirm the convergence properties. The robustness of the weighted particle method is shown to contrast with two Direct Simulation Algorithms which develop instabilities.
- ItemBilinear coagulation equations(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2019) Heydecker, Daniel; Patterson, Robert I.A.We consider coagulation equations of Smoluchowski or Flory type where the total merge rate has a bilinear form π(y) · Aπ (x) for a vector of conserved quantities π, generalising the multiplicative kernel. For these kernels, a gelation transition occurs at a finite time tg ∈ (0,∞), which can be given exactly in terms of an eigenvalue problem in finite dimensions. We prove a hydrodynamic limit for a stochastic coagulant, including a corresponding phase transition for the largest particle, and exploit a coupling to random graphs to extend analysis of the limiting process beyond the gelation time.
- ItemMolecular epidemiology of methicillin-susceptible and methicillin-resistant staphylococcus aureus in wild, captive and laboratory rats: Effect of habitat on the Nasal S. aureus Population(Basel : MDPI, 2020) Raafat, Dina; Mrochen, Daniel M.; Al’Sholui, Fawaz; Heuser, Elisa; Ryll, René; Pritchett-Corning, Kathleen R.; Jacob, Jens; Walther, Bernd; Matuschka, Franz-Rainer; Richter, Dania; Westerhüs, Uta; Pikula, Jiri; van den Brandt, Jens; Nicklas, Werner; Monecke, Stefan; Strommenger, Birgit; van Alen, Sarah; Becker, Karsten; Ulrich, Rainer G.; Holtfreter, SilvaRats are a reservoir of human- and livestock-associated methicillin-resistant Staphylococcus aureus (MRSA). However, the composition of the natural S. aureus population in wild and laboratory rats is largely unknown. Here, 144 nasal S. aureus isolates from free-living wild rats, captive wild rats and laboratory rats were genotyped and profiled for antibiotic resistances and human-specific virulence genes. The nasal S. aureus carriage rate was higher among wild rats (23.4%) than laboratory rats (12.3%). Freeliving wild rats were primarily colonized with isolates of clonal complex (CC) 49 and CC130 and maintained these strains even in husbandry. Moreover, upon livestock contact, CC398 isolates were acquired. In contrast, laboratory rats were colonized with many different S. aureus lineages-many of which are commonly found in humans. Five captive wild rats were colonized with CC398-MRSA. Moreover, a single CC30-MRSA and two CC130-MRSA were detected in free-living or captive wild rats. Rat-derived S. aureus isolates rarely harbored the phage-carried immune evasion gene cluster or superantigen genes, suggesting long-term adaptation to their host. Taken together, our study revealed a natural S. aureus population in wild rats, as well as a colonization pressure on wild and laboratory rats by exposure to livestock- and human-associated S. aureus, respectively. © 2020 by the authors.
- ItemProperties of the solutions of delocalised coagulation and inception problems with outflow boundaries(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2015) Patterson, Robert I.A.Well posedness is established for a family of equations modelling particle populations undergoing delocalised coagulation, advection, inflow and outflow in a externally specified velocity field. Very general particle types are allowed while the spatial domain is a bounded region of d-dimensional space for which every point lies on exactly one streamline associated with the velocity field. The problem is formulated as a semi-linear ODE in the Banach space of bounded measures on particle position and type space. A local Lipschitz property is established in total variation norm for the propagators (generalised semi-groups) associated with the problem and used to construct a Picard iteration that establishes local existence and global uniqueness for any initial condition. The unique weak solution is shown further to be a differentiable or at least bounded variation strong solution under smoothness assumptions on the parameters of the coagulation interaction. In the case of one spatial dimension strong differentiability is established even for coagulation parameters with a particular bounded variation structure in space. This one dimensional extension establishes the convergence of the simulation processes studied in [Patterson, textitStoch. Anal. Appl. 31, 2013] to a unique and differentiable limit.