Redox Cycling for Passive Modification of Polypyrrole Surface Properties: Effects on Cell Adhesion and Proliferation

Abstract

The surface properties of electrodeposited poly(pyrrole) (Ppy) doped with sodium dodecylbenzenesulphonate (NaDBS) are modified by two methods: addition of poly(ethylene glycol) (PEG) during the electrodeposition and through redox cycling post electrodeposition. X-ray photoelectron spectroscopy (XPS) was used to ascertain PEG incorporation and to analyze the change in the oxidation state of the polymer. Anodic cycling resulted in the formation of micrometer-sized surface cracks which increased the amount of Rhodamine-B dye adsorbed onto the surface, and played a role in decreasing the wettability of the surface. The change in surface wettability caused by these cracks was mitigated by the presence of PEG in the Ppy matrix. Compared to the incorporation of PEG, redox cycling was more effective in passively modulating the adhesion of NIH 3T3 fibroblast cells on the Ppy surface. Based on the attenuation of surface polarity of the Ppy surfaces by the incorporated PEG, a mechanism is proposed to explain the observed cell adhesion behavior.

Protective coatings for intraocular wirelessly controlled microrobots for implantation: Corrosion, cell culture, and in vivo animal tests

“…In particular, a microcracked surface was noticed for the Ppy‐coated microrobots [Figure (D)]. The cracks typically occur due to the Ppy doping process . Na, Ca, Cl, O, and P elements originating from the HBSS solution residue [see Figure (B)] were typically detected in the corresponding EDX patterns (data not shown).…”

“…A minimum of four samples was used for in vitro cell experiments. The MTT assay is a common and standard assay to assess cell proliferation as readout for toxicity and is routinely performed with antibiotics in the test medium . Although it is generally possible to perform the assay without antibiotics, they were used in the first toxicity screening for monitoring potential adverse effects of the microrobots reported here.…”

“…Ppy can be prepared as a conformal functional coating onto microstructures of different shapes. Its surface properties can be electrochemically tuned due to its property of redox switching …”

A critical review of cell culture strategies for modelling intracortical brain implant material reactions

“…The murine 3T3 fibroblast strain (Fig. 6C) is also common [92,93]. These cell types allow for high throughput screening assays at relatively low cost and with ease of scalability [23,94].…”

“…A novel biomaterial may not immediately affect cell viability, as the toxicological impact might be more discrete and affect cell capacity to proliferate [97]. Common methods to assess the proliferative ability of cells include metabolic activity assays using enzyme base processes such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay) [92,97,98] and 5-Bromo-2 0 -Deoxyuridine (BrdU) [98]. Lastly the cell material interaction might not produce toxicity in terms of causing measurable effects on viability or proliferation in the experimental time frames but induce changes in the metabolic function [89].…”