Corinna M. Preuss

Controlled Cell Adhesion on Poly(dopamine) Interfaces Photopatterned with Non‐Fouling Brushes

Bioinspired poly(dopamine) (PDA) films are merged with antifouling poly(MeOEGMA) brushes utilizing a nitrile imine-mediated tetrazole-ene cycloaddition (NITEC)-based phototriggered surface encoding protocol. The antifouling brushes were photopatterned on PDA surfaces, leading cells to form confluent layers in the non-irradiated sections, while no adhesion occurred on the brushes resulting in a remarkably precise cell pattern. The presented strategy paves the way for the design of tailor-made patterned cell interfaces.

Biomimetic Dopamine‐Diels–Alder Switches

Mussel adhesives function as tools for surface modifications of a wide variety of materials due to their remarkable adhesion properties. Herein, a combination of bioinspired mussel adhesives based on a dopamine derivative, polymer chemistry, and well-established Diels-Alder (DA) chemistry leads to a bioinspired switchable surface system that possesses the capability of attaching and detaching specific polymers on demand. A dopaminemaleimide compound, which has been attached to a gold surface under maritime conditions undergoes DA- and retro-DA-click-conjugations with cyclopentadiene-carrying PEG chains. The surface attachment and the subsequent DA/rDA cycles are evidenced via XPS analysis.

Suppressing Pseudomonas aeruginosa adhesion via non-fouling polymer brushes

In the current study, well-defined polymer brushes are shown as an effective surface modification to resist biofilm formation from opportunistic pathogens. Poly[oligo(ethylene glycol)methyl ether methacrylate] (poly(MeOEGMA)) and poly[N-(2-hydroxypropyl)methacrylamide] (poly(HPMA)) brushes were grown by surface initiated atom transfer radical polymerization (SI-ATRP) and subsequently characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and dynamic water contact angle measurements. Their remarkable resistance to protein fouling after long term contact with biological media was evidenced by surface plasmon resonance spectroscopy. Challenging these brushes with an environmental strain of Pseudomonas aeruginosa in mineral media as well as a casein–soja–pepton–agar (CASO) medium resulted in no biofilm formation, while a decrease of the biofilm formation by 70% (poly(HPMA)) and 90% (poly(MeOEGMA)) was observed when the medium was rich in nutrients and proteins (fetal bovine serum). In contrast to the antibiotic sensitive strains, biofilm formation was observed using an antibiotic multi-resistant P. aeruginosa strain on both brushes. Protein fouling was fully prevented on both types of brushes, which might challenge the proposed mechanism of biofilm formation mediated by a pre-formed conditioning film of proteins. The resistance to biofilm formation and the possibility to precisely control their growth and functionalities makes these brushes ((poly(HPMA) and (poly(MeOEGMA)) promising candidates for surface modification of various biomaterials as well as platforms for basic studies into the mechanisms of bacteria fouling.

Hetero Diels–Alder Chemistry for the Functionalization of Single‐Walled Carbon Nanotubes with Cyclopentadienyl End‐Capped Polymer Strands

Single-walled carbon nanotubes (SWCNTs) are pre-functionalized with a pyridinyl-based dithioester to undergo a hetero Diels-Alder (HDA) reaction with cyclopentadienyl end-capped poly(methyl)methacrylate (Mn = 2700 g mol(-1) , PDI = 1.14). Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis (EA), and X-ray photoelectron spectroscopy (XPS) evidence the success of the grafting process. The estimated resulting grafting density (from XPS and EA) via the HDA reaction increases by a factor of more than two (0.0774 chains·nm(-2) via XPS) compared with typical values obtained via a direct cyclopentadiene driven Diels-Alder conjugation onto non-functional SWCNTs under similar conditions.