Polarization of Macrophages, Cellular Adhesion, and Spreading on Bacterially Contaminated Gold Nanoparticle-Coatings .

Biomaterial-associated infections often arise from contaminating bacteria adhering to an implant surface that are introduced during surgical implantation and not effectively eradicated by antibiotic treatment. Whether or not infection develops from contaminating bacteria depends on an interplay between bacteria contaminating the biomaterial surface and tissue cells trying to integrate the surface with the aid of immune cells. The biomaterial surface plays a crucial role in defining the outcome of this race for the surface.

Unidirectional rotating molecular motors dynamically interact with adsorbed proteins to direct the fate of mesenchymal stem cells.

Artificial rotary molecular motors convert energy into controlled motion and drive a system out of equilibrium with molecular precision. The molecular motion is harnessed to mediate the adsorbed protein layer and then ultimately to direct the fate of human bone marrow-derived mesenchymal stem cells (hBM-MSCs). When influenced by the rotary motion of light-driven molecular motors grafted on surfaces, the adsorbed protein layer primes hBM-MSCs to differentiate into osteoblasts, while without rotation, multipotency is better maintained.

Using γ-Ray Polymerization-Induced Assemblies to Synthesize Polydopamine Nanocapsules.

This work reports a simple and robust strategy for synthesis of polydopamine nanocapsules (PDA NCs). First, polymer assemblies were synthesized by a γ-ray-induced liquid-liquid (HO-acrylate) interface polymerization strategy, in the absence of any surfactants. H nuclear magnetic resonance analysis and molecular dynamics simulation reveal that the generation of polymer assemblies largely depends on the hydrophilicity of acrylate and gravity of the oligomers at the interface.

Comparison of the Responsivity of Solution-Suspended and Surface-Bound Poly(N-isopropylacrylamide)-Based Microgels for Sensing Applications.

In this submission, the phase transition behavior for poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) microgels and their assemblies was investigated as a function of temperature and pH using UV-vis spectroscopy (to probe light scattering behavior) and quartz crystal microbalance with dissipation (QCM-D) measurements. PNIPAm-co-AAc microgels were "painted" onto Au-coated glass substrates (for UV-vis) and the Au electrode of a QCM crystal to generate monolayers. The subsequent deposition of another Au layer on top of the pNIPAm-co-AAc microgel layer yields what is known as an etalon.

Long-range interactions between protein-coated particles and POEGMA brush layers in a serum environment.

Hydrophilic poly[oligo(ethylene glycol) methyl methacrylate] (POEGMA) brush layers with different thickness and graft densities were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) to construct a model surface to examine protein-surface interactions in a serum environment. The thickness of the POEGMA brush layers could be well controlled by the polymerization time and density of the immobilized initiators. The interactions between these brush-modified surfaces and the protein-coated polystyrene (PS) particles in newborn calf serum (NBCS) environment were then measured by total internal reflection microscopy (TIRM).

"Hearing Loss" in QCM Measurement of Protein Adsorption to Protein Resistant Polymer Brush Layers.

Accurate quantification of nonspecific protein adsorption on biomaterial surfaces is essential for evaluation of their antifouling properties. The quartz crystal microbalance (QCM) is an acoustic sensor widely used for the measurement of protein adsorption. However, although the QCM is highly sensitive, it does have performance limitations when working with surfaces modified with thick viscous layers.

Surfaces having dual affinity for plasminogen and tissue plasminogen activator: in situ plasmin generation and clot lysis.

Surface modification with affinity ligands capable of capturing bioactive molecules in situ is a widely used strategy for developing biofunctional materials. However, many bioactive molecules, for example zymogens, exist naturally in a "quiescent" state, and become active only when "triggered" by specific activators. In the present study, in situ activation of a surface-integrated zymogen was achieved by introducing affinity ligands for both the zymogen and its activator.

Surface immobilization of a protease through an inhibitor-derived affinity ligand: a bioactive surface with defensive properties against an inhibitor.

The concept of enzyme immobilization via an inhibitor-derived peptide was developed. This method of immobilization was shown to be advantageous over physical adsorption and covalent bonding in retaining the enzymatic activity. Moreover, the surface-immobilized enzyme exhibited resistance against its inhibitor due to the occupation of an inhibitor binding site on the enzyme.

Conjugation of polymers to proteins through an inhibitor-derived peptide: taking up the inhibitor "berth".

A hexapeptide derived from an enzyme inhibitor was used as an affinity ligand for the conjugation of a hydrophilic polymer to the enzyme. The peptide targeted the polymer to the "berth" of the inhibitor in the enzyme, affording the enzyme resistance to the inhibitor without affecting the enzymatic activity.

A t-PA/nanoparticle conjugate with fully retained enzymatic activity and prolonged circulation time.

A major issue in the therapeutic use of tissue plasminogen activator (t-PA) for the treatment of thrombotic diseases is its very short half-life in the circulation due to the effects of inhibitors. The present study aims to resolve the issue using a t-PA/gold nanoparticle (t-PA/AuNP) conjugate prepared via bio-affinity ligation under physiological conditions. The ligation is based on the specific interactions between t-PA and ε-lysine (a ligand that has affinity to a specific domain in t-PA) immobilized on the AuNP surface through polyvinyl pyrrolidone (PVP) as a spacer.

Thermoresponsive copolymer decorated surface enables controlling the adsorption of a target protein in plasma.

The control of protein/surface interactions by external stimuli is often required in bioapplications such as bioseparation and biosensors. Although regulation of protein adsorption has been achieved on the surfaces modified with stimuli-responsive polymers, controlled protein adsorption is still challenging for a target protein in a multiprotein system. The present study developed a concept of surface design for the controlled adsorption of a specific protein from plasma by combining a thermoresponsive polymer with an affinity ligand on the surface.

A versatile, fast, and efficient method of visible-light-induced surface grafting polymerization.

To overcome the problem caused by the lability of the Au-S bond, we demonstrate the first use of Mn2(CO)10 for visible-light-induced surface grafting polymerization on Au surfaces in this paper. The visible-light-induced surface grafting of poly(N-isopropylacrylamide) (PNIPAAm) has the features of a "controlled" polymerization, which is characterized by a linear relationship between the thickness of the grafting layer and the monomer concentration. Ellipsometry indicated the formation of PNIPAAm films of up to ∼200 nm in thickness after only 10 min of polymerization at room temperature, demonstrating that this is a very fast process in comparison with traditional grafting polymerization techniques.

125I-radiolabeling, surface plasmon resonance, and quartz crystal microbalance with dissipation: three tools to compare protein adsorption on surfaces of different wettability.

The extent of protein adsorption is an important consideration in the biocompatibility of biomaterials. Various experimental methods can be used to determine the quantity of protein adsorbed, but the results usually differ. In the present work, self-assembled monolayers (SAMs) were used to prepare a series of model gold surfaces varying systematically in water wettability, from hydrophilic to hydrophobic.

Control of lysozyme adsorption by pH on surfaces modified with polyampholyte brushes.

The adsorption of lysozyme is difficult to control by pH because of the relatively high isoelectric point of this protein (11.1). In this article, we demonstrate good control of lysozyme adsorption by pH in the range of 4-10 on silicon surfaces through modification with poly(2-(dimethylamino ethyl) methacrylate)-block-poly(methacrylic acid) (PDMAEMA-b-PMAA) diblock copolymer brushes.