Ryosuke Ogaki

Assembly of Poly(dopamine) Films Mixed with a Nonionic Polymer

Poly(dopamine) (PDA) coatings have recently attracted considerable interest for a variety of applications. Here, we investigate the film deposition of dopamine mixed with a nonionic polymer (i.e., poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), and poly(N-vinyl pyrrolidone) (PVP)) onto silica substrates using X-ray photoelectron spectroscopy and quartz crystal microbalance. Furthermore, we assess the possibility of coating silica colloids to yield polymer capsules and liposomes with these mixtures. We found that mixed PDA/PEG and PDA/PVA films are deposited without the need for a covalent linker such as an amine or thiol. We also discovered the first material, namely, PVP, that can suppress PDA film assembly. These fundamental findings give further insight into PDA film properties and contribute to establish PDA as a widely applicable coating.

Polydopamine/Liposome Coatings and Their Interaction with Myoblast Cells

Surface-mediated drug delivery is a recent concept, where active surface coatings are employed to deliver therapeutic cargo to cells. Herein, we explore the potential of liposomes embedded in polydopamine (PDA) coatings to serve as drug deposits stored on planar substrates. We quantify the PDA growth rate on glass by XPS and show that PDA coatings support myoblast adherence and proliferation. Further, PDA capping layers were deposited on glass substrates precoated with poly(L-lysine) and zwitterionic liposomes. Already thin PDA capping layers render liposome coated surfaces cell adhesive. We experimentally show for the first time, the internalization of a model hydrophobic cargo, that is, fluorescent lipids embedded within the lipid bilayer of liposomes by the cells from the surface. This is evident from the fluorescence exhibited by the cells grown on PDA coatings containing fluorescently labeled liposomes, with the highest fluorescent intensity found in the close proximity of the cell nuclei. The cargo uptake efficiency depends on the thickness of the PDA capping layer and the cell residence time on the coated substrates. Taken together, we demonstrate the first step toward the establishment of a versatile approach using liposomal drug deposits in polymer thin films for surface-mediated drug delivery.

Routing of individual polymers in designed patterns

Synthetic polymers are ubiquitous in the modern world, but our ability to exert control over the molecular conformation of individual polymers is very limited. In particular, although the programmable self-assembly of oligonucleotides and proteins into artificial nanostructures has been demonstrated, we currently lack the tools to handle other types of synthetic polymers individually and thus the ability to utilize and study their single-molecule properties. Here we show that synthetic polymer wires containing short oligonucleotides that extend from each repeat can be made to assemble into arbitrary routings. The wires, which can be more than 200 nm in length, are soft and bendable, and the DNA strands allow individual polymers to self-assemble into predesigned routings on both two- and three-dimensional DNA origami templates. The polymers are conjugated and potentially conducting, and could therefore be used to create molecular-scale electronic or optical wires in arbitrary geometries.

Chemical patterning in biointerface science

Patterning of surfaces with different chemistries provides novel insights into how proteins, cells and tissues interact with materials. New materials, and the properties that their surfaces impart, are highly desirable for the next generation of implants, regenerative medicine and tissue engineering devices, and biosensors and drug delivery devices for disease diagnosis and treatment. Patterning is thus seen as a key technology driver for these materials. We provide an overview of state-of-the-art fabrication tools for creating chemical patterns over length scales ranging from millimeters to micrometers to nanometers. The importance of highly sensitive surface analytical tools in the development of new chemically patterned surfaces is highlighted.

Liposomes as Drug Deposits in Multilayered Polymer Films

The ex vivo growth of implantable hepatic or cardiac tissue remains a challenge and novel approaches are highly sought after. We report an approach to use liposomes embedded within multilayered films as drug deposits to deliver active cargo to adherent cells. We verify and characterize the assembly of poly(l-lysine) (PLL)/alginate, PLL/poly(l-glutamic acid), PLL/poly(methacrylic acid) (PMA), and PLL/cholesterol-modified PMA (PMAc) films, and assess the myoblast and hepatocyte adhesion to these coatings using different numbers of polyelectrolyte layers. The assembly of liposome-containing multilayered coatings is monitored by QCM-D, and the films are visualized using microscopy. The myoblast and hepatocyte adhesion to these films using PLL/PMAc or poly(styrenesulfonate) (PSS)/poly(allyl amine hydrochloride) (PAH) as capping layers is evaluated. Finally, the uptake of fluorescent lipids from the surface by these cells is demonstrated and compared. The activity of this liposome-containing coating is confirmed for both cell lines by trapping the small cytotoxic compound thiocoraline within the liposomes. It is shown that the biological response depends on the number of capping layers, and is different for the two cell lines when the compound is delivered from the surface, while it is similar when administered from solution. Taken together, we demonstrate the potential of liposomes as drug deposits in multilayered films for surface-mediated drug delivery.

Spatial Mapping and Quantification of Soft and Hard Protein Coronas at Silver Nanocubes

Protein coronas around silver nanocubes were quantified in serum-containing media using localized surface plasmon resonances. Both soft and hard coronas showed exposure-time and concentration-dependent changes in protein surface density with time-dependent hardening. We observed spatially dependent kinetics of the corona-formation at cube edges/corners versus facets at short incubation times, where the polymer stabilization agent delayed corona hardening. The soft corona contained more protein than the hard corona at all time-points (8-fold difference with 10% serum conditions).

Assembly of Poly(dopamine)/Poly(N-isopropylacrylamide) Mixed Films and Their Temperature-Dependent Interaction with Proteins, Liposomes, and Cells

Many biomedical applications benefit from responsive polymer coatings. The properties of poly(dopamine) (PDA) films can be affected by codepositing dopamine (DA) with the temperature-responsive polymer poly(N-isopropylacrylamide) (pNiPAAm). We characterize the film assembly at 24 and 39 °C using DA and aminated or carboxylated pNiPAAm by a quartz crystal microbalance with dissipation monitoring (QCM-D), X-ray photoelectron spectroscopy, UV-vis, ellipsometry, and atomic force microscopy. It was found that pNiPAAm with both types of end groups are incorporated into the films. We then identified a temperature-dependent adsorption behavior of proteins and liposomes to these PDA and pNiPAAm containing coatings by QCM-D and optical microscopy. Finally, a difference in myoblast cell response was found when these cells were allowed to adhere to these coatings. Taken together, these fundamental findings considerably broaden the potential biomedical applications of PDA films due to the added temperature responsiveness.

Highly-branched poly(N-isopropylacrylamide) as a component in poly(dopamine) films

Mixed one-step poly(dopamine) (PDA)/highly branched poly(N-isopropylacrylamide) (pNiPAAm) coatings have been assembled and characterized by X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, atomic force microscopy, and quartz crystal microbalance with dissipation monitoring (QCM-D) depending on the deposition temperature below and above the lower critical solution temperature (LCST) of the pNiPAAm. Mixed films were confirmed. The protein adsorption at 24 °C was found to be reduced with increasing amount of pNiPAAm in the mixed coatings, while there was no difference observed for proteins deposition at 39 °C. Further, the ability of these mixed coatings in comparison to the pure PDA and pNiPAAm films to serve as capping layer for surface-immobilized zwitterionic or positively charged liposomes has been assessed by QCM-D. The adhesion of hepatocytes, macrophages, and myoblast to these liposomes-containing hybrid coatings and the uptake of fluorescent lipids from the surface by the adhering cells depending on the capping layers were compared. The latter aspect was found to be dependent on the used capping layer and the type of liposome as carrier for the fluorescent lipid, with the highest uptake found for positive liposomes and pure pNiPAAm as capping layer. Taken together, the assembled hybrid coatings have the potential to be used as functional coatings toward surface-mediated drug delivery.

Decreased material-activation of the complement system using low-energy plasma polymerized poly(vinyl pyrrolidone) coatings

In the current study we investigate the activation of blood complement on medical device silicone rubber and present a plasma polymerized vinyl pyrrolidone (ppVP) coating which strongly decreases surface-activation of the blood complement system. We show that uncoated silicone and polystyrene are both potent activators of the complement system, measured both as activated, deposited C3b and quantifying fluid-phase release of the cleavage fragment C3c. The ppVP coated silicone exhibits approximately 90% reduced complement activation compared to untreated silicone. Quartz crystal microbalance with dissipation (QCM-D) measurements show relatively strong adsorption of blood proteins including native C3 to the ppVP surface, indicating that reduction of complement activation on ppVP is neither a result of low protein adsorption nor lower direct C3-binding, and is therefore possibly a consequence of differences in the adsorbed protein layer composition. The alternative and classical complement pathways are barely detectable on ppVP while the lectin pathway through MBL/ficolin-2 deposition remains active on ppVP suggesting this pathway is responsible for the remaining subtle activation on the ppVP coated surface. The ppVP surface is furthermore characterized physically and chemically using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR), which indicates preservation of chemical functionality by the applied plasma process. Overall, the ppVP coating shows a potential for increasing complement-compatibility of blood-contacting devices.

Dopamine-assisted rapid fabrication of nanoscale protein arrays by colloidal lithography.

The development of cost-effective methodologies for the precise nanometer-scale positioning of biomolecules permits the low-cost production of various biofunctional devices for a range of biomedical and nanotechnological applications. By combining colloidal lithography and the mussel-inspired multifunctional polydopamine coating, we present a novel parallel benchtop method that allows rapid nanoscale patterning of proteins without the need for electrically powered equipment in the fabrication process. The PDA-immobilized binary nanopattern consisting of BSA surrounded by PLL-g-PEG is fabricated over a large area, and the integrity of the pattern is confirmed using AFM and FM.