Biofouling constitutes a major challenge in the application of biosensors and biomedical implants, as well as for (food) packaging and marine equipment. In this work, an antifouling surface coating based on the combination of mussel-inspired dendritic polyglycerol (MI-dPG) and an amine-functionalized block copolymer of linear polyglycerol (lPG−b−OA 11 , OA = oligo-amine) was developed. The coating was compared to a MI-dPG surface which was postfunctionalized with commercially available amine-terminated polyethylene glycol (HO−PEG−NH 2 ) of similar molecular weight. In the current work, these coatings were compared in their chemical stability, protein fouling characteristics, and cell fouling characteristics. The lPG−b−OA 11 -functionalized coating showed high chemical stability in both phosphate buffered saline (PBS) and sodium dodecyl sulfate (SDS) solutions and reduced the adhesion of fibrinogen from human plasma with 99% and the adhesion of human serum albumin with 96%, in comparison to the bare titanium dioxide substrate. Furthermore, the proliferation of human umbilical vein endothelial cells (HUVECs) was reduced with 85% when the lPG−b−OA 11 system was compared to bare titanium dioxide. Additionally, a reduction of 94% was observed when the lPG−b−OA 11 system was compared to tissue culture polystyrene.

Adsorption of enzymes on solid surfaces may lead to conformational changes that reduce their catalytic conversion activity and are thus detrimental to the efficiency of biotechnology or biosensing applications. This work is a joint theoretical and experimental endeavor in which we identify and quantify the conformational changes that 1 Page 2 of 46 ACS Paragon Plus Environment ACS Biomaterials Science & Engineering chymotrypsin undergoes when in contact with the surface of amorphous silica nanoparticles. For this purpose, we use circular dichroism spectroscopy, standard molecular dynamics and advanced-sampling methods. Only the combination of these techniques allowed us to pinpoint a destabilization effect of silica on specific structural motifs of chymotrypsin. They are linked by the possibility of theoretically predicting CD spectra, allowing us to elucidate the source of the experimentally observed spectral changes.We find that chymotrypsin loses part of its helical content upon adsorption, with minor perturbation of its overall tertiary structure, associated to changes in the aromatic interactions. We demonstrate that the C-terminal helical fragment is unfolded as an isolated oligopeptide in pure water, folded as an α-helix as terminus of chymotrypsin in solution, and again partly disordered when the protein is adsorbed on silica. We believe that the joint methodology introduced in this manuscript has a direct general applicability to investigate any biomolecule -inorganic surface system. Methods to theoretically predict Circular Dichroism spectra from atomistic simulations were compared and improved. The drawbacks of the approaches are discussed; in particular the limited capability of advanced-sampling MD schemes to explore the conformational phase space of large proteins, and the dependency of the predicted ellipticity bands on the choice of calculation parameters.

Stainless steel AISI 304 surfaces were studied after a mild anodic polarization for oxide growth in the presence and absence of two derivatives of vitamin B2 (riboflavin and flavin mononucleotide) that can be secreted by metal‐reducing bacteria and act as a chelating agent for iron species. The alterations in oxide chemistry were studied by means of surface‐sensitive techniques such as X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry analysis. The complementary electrochemical characterization revealed a preferential growth of an oxide/hydroxide iron‐rich film that is responsible for an altered pit initiation and nucleation behavior. These findings suggest that as the corrosion behavior is determined by the interplay of the chemical and electronic properties, only a mild anodic polarization in the presence of redox‐active molecules is able to alter the chemical and electronic structure of the passive film formed on stainless steel AISI 304. This helps to achieve a profound understanding of the mechanisms of microbially influenced corrosion (MIC) and especially the possible effects of the redox‐active biomolecules, as they may play an important role in the corrosion susceptibility of stainless steel surfaces.

While successful in the structural determination of ordered biomolecules, the spectroscopic investigation of oligopeptides in solution is hindered by their complex and rapidly changing conformational ensemble. The measured circular dichroism (CD) spectrum of an oligopeptide is an average of the signals coming from all the ensemble of microstates, severely limiting its interpretation, in contrast to the successful structural determination of ordered biomolecules. Spectral deconvolution methods to estimate the secondary structure contributions in the ensemble are still mostly based on databases of larger ordered proteins. Here we establish how the interpretation of CD spectra of oligopeptides can be enhanced by the ability to compute the same observable from a set of atomic coordinates. Focusing on two representative oligopeptides featuring a known propensity towards an α-helical and β-hairpin motif, respectively, we compare and cross-validate the structural information coming from: deconvolution of the experimental CD spectra, sequence-based de novo structure prediction and molecular dynamics simulations based on enhanced sampling methods. We find that small conformational variations can give rise to significant changes in the CD signals. Therefore, while for the simpler conformational landscape of the α-helical peptide de novo structure prediction can already give reasonable agreement with the experiment, an extended ensemble of conformers needs to be considered for the β-hairpin sequence.

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The development of the microbiologically influenced corrosion (MIC)-specific inductively coupled plasma-time of flight-mass spectrometry (ICP-ToF-MS) analytical method presented here, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis. For this, a MIC-specific staining procedure was developed which ensures the analysis of intact cells. It allows the analysis of archaea at a single cell level which is extremely scarce compared to other well characterized organisms. The detection method revealed elemental selectivity for the corrosive methanogenic strain Methanobacterium-affiliated IM1. Hence, the possible uptake of individual elements from different steel samples was investigated and results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to uptake chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The methods developed and information obtained will be used in the future to elucidate underlying mechanisms, compliment well-developed methods, such as SEM-EDS, and develop novel material protection concepts.

The initial attachment and subsequent biofilm formation of electroactive bacteria Shewanella putrefaciens CN32 was investigated to clarify the influence of organic conditioning layers. A selection of macromolecules and self-assembled monolayers (SAMs) of different chain lengths and functional groups were prepared and characterized by means of infrared spectroscopy in terms of their chemistry. Surface energy and Zeta (ζ-) potential of the conditioning layers was determined with contact angle and streaming current measurements. Among the studied surface parameters, a high polar component and a high ratio of polar-to-disperse components of the surface energy has emerged as a successful indicator for the inhibition of the initial settlement of S. putrefaciens on stainless steel AISI 304 surfaces. Considering the negative surface charge of planktonic S. putrefaciens cells, and the strong inhibition of cell attachment by positively charged polyethylenimine (PEI) conditioning layers, our results indicate that electrostatic interactions do play a subordinate role in controlling the attachment of this microorganism on stainless steel AISI 304 surfaces. For the biofilm formation, the organization of the SAMs affected the local distribution of the biofilms. The formation of three-dimensional and patchy biofilm networks was promoted with increasing disorder of the SAMs.