Search results for "polymers"

Linear infrared dichroism by a double modulation technique

1991

In the first part of this paper an experimental setup using Fourier-transform infrared spectroscopy (FTIR) in combination with a photoelastic modulator (PEM) for linear dichroism measurements is described. The second part shows the influence of PEM-amplitude and scan-velocity on the sensitivity of the instrument. The third part deals with the fringe-problem in the baselines of absorbance spectra and its influence on the determination of the linear dichroic ratio.

When Functionalization of PLA Surfaces Meets Thiol−Yne Photochemistry: Case Study with Antibacterial PolyaspartamideDerivatives

2014

International audience; In this work we wish to report on the covalent functionalization of polylactide (PLA) surfaces by photoradical thiol–yne to yield antibacterial surfaces. At first, hydrophilic and hydrophobic thiol fluorescent probes are synthesized and used to study and optimize the conditions of ligation on alkyne-PLA surfaces. In a second part, a new antibacterial polyaspartamide copolymer is covalently grafted. The covalent surface modification and the density of surface functionalization are evaluated by SEC and XPS analyses. No degradation of PLA chains is observed, whereas covalent grafting is confirmed by the presence of S2p and N1s signals. Antiadherence and antibiofilm acti…

Macromol. Rapid Commun. 24/2010

2010

Highly Branched Polymers: Recent Innovations and Exciting Challenges

2007

Prof. Rolf Mülhaupt from the University of Freiburg is the recipient of the Hermann Staudinger Award 2009

2009

Ionic Hydrogel Based on Chitosan Cross-Linked with 6-Phosphogluconic Trisodium Salt as a Drug Delivery System.

2018

[EN] In this work, 6-phosphogluconic trisodium salt (6-PG(-)Na(+)) is introduced as a new aqueous and nontoxic cross-linking agent to obtain ionic hydrogels. Here, it is shown the formation of hydrogels based on chitosan cross-linked with 6-PG(-)Na(+). This formulation is obtained by ionic interaction of cationic groups of polymer with anionic groups of the cross linker. These hydrogels are nontoxic, do not cause dermal irritation, are easy to extend, and have an adequate adhesion force to be applied as polymeric film over the skin. This AWN formulation exhibits a first order release kinetic and can be applied as drug vehicle for topical administration or as wound dressing for wound healing…

Click modification of multifunctional liposomes bearing hyperbranched polyether chains.

2014

Aiming at controlled modification of liposomal surface structures, we describe a postpreparational approach for surface derivatization of a new type of multifunctional, sterically stabilized liposomes. Application of dual centrifugation (DC) resulted in high encapsulation efficiencies above 50% at very small batch sizes with a total volume of 150 μL, which were conductive to fast and efficient optimization of variegated surface modification reactions. Cholesterol-polymer amphiphiles, including complex hyperbranched polyether structures bearing 1-4 terminal alkynes, were used in DC formulations to provide steric stabilization. The alkyne moieties were explored as anchors for the conjugation …

Aggregation behavior of amphiphilic p(HPMA)-co-p(LMA) copolymers studied by FCS and EPR spectroscopy.

2012

A combined study of fluorescence correlation spectroscopy and electron paramagnetic resonance spectroscopy gave a unique picture of p(HPMA)-co-p(LMA) copolymers in aqueous solutions, ranging from the size of micelles and aggregates to the composition of the interior of these self-assembled systems. P(HPMA)-co-p(LMA) copolymers have shown high potential as brain drug delivery systems, and a detailed study of their physicochemical properties can help to elucidate their mechanism of action. Applying two complementary techniques, we found that the self-assembly behavior as well as the strength of hydrophobic attraction of the amphiphilic copolymers can be tuned by the hydrophobic LMA content or…

Functionalization of Liposomes with Hydrophilic Polymers Results in Macrophage Uptake Independent of the Protein Corona

2019

Liposomes are established drug carriers that are employed to transport and deliver hydrophilic drugs in the body. To minimize unspecific cellular uptake, nanocarriers are commonly modified with poly(ethylene glycol) (PEG), which is known to minimize unspecific protein adsorption. However, to date, it has not been studied whether this is an intrinsic and specific property of PEG or if it can be transferred to hyperbranched polyglycerol (hbPG) as well. Additionally, it remains unclear if the reduction of unspecific cell uptake is independent of the “basic” carrier at which a surface functionalization with polymers is usually applied. Therefore, we studied the protein corona of differently fun…

Joining Two Natural Motifs: Catechol-Containing Poly(phosphoester)s.

2017

Numerous catechol-containing polymers, including biodegradable polymers, are currently heavily discussed for modern biomaterials. However, there is no report combining poly(phosphoester)s (PPEs) with catechols. Adhesive PPEs have been prepared via acyclic diene metathesis polymerization. A novel acetal-protected catechol phosphate monomer was homo- and copolymerized with phosphoester comonomers with molecular weights up to 42000 g/mol. Quantitative release of the catechols was achieved by careful hydrolysis of the acetal groups without backbone degradation. Degradation of the PPEs under basic conditions revealed complete and statistical degradation of the phosphotri- to phosphodiesters. In …