Optimizing the Bacteriostatic and Cytocompatibility Properties of Poly(hexamethylene guanidine) Hydrochloride (PHMG) via the Guanidine/Alkane Ratio.

The emergence of "superbugs" is not only problematic and potentially lethal for infected subjects but also poses serious challenges for the healthcare system. Although existing antibacterial agents have been effective in some cases, the side effects and biocompatibility generally present difficulties. The development of new antibacterial agents is therefore urgently required.

Robust, anti-biofouling 2D nanogel films from poly(-vinyl caprolactam--vinylimidazole) polymers.

In analogy with adsorbed protein films, we have fabricated a family of 2D nanofilms composed of poly(-vinyl caprolactam--vinylimidazole) (PNVCL) nanogels. NVCL was copolymerized with 1-vinylimidazole (VIM), and then cross-linked with α,ω-dibromoalkanes with 2 to 8 carbons quaternization to form the nanogels. The swelling ratio of the gels was precisely controlled by regulating the inter-chain spacing of the polymers at the level of the carbon atom chain length of the cross-linker.

One-step surface modification strategy with composition-tunable microgels: From bactericidal surface to cell-friendly surface.

As modifiers for biomaterial surfaces, soft colloidal particles not only have good film-forming properties, but can also contribute to the function of the biomaterial via their chemical and biological properties. This general approach has proven effective for surface modification, but little is known about methods to control the properties of the colloidal particles to regulate film formation and biological function. In this work, we prepared poly (N-isopropylacrylamide) microgels (ZQP) containing both a zwitterionic component (Z) to provide anti-fouling functionality, and a quaternary ammonium salt (Q) to give bactericidal functionality.

Dual-Functional Surfaces Based on an Antifouling Polymer and a Natural Antibiofilm Molecule: Prevention of Biofilm Formation without Using Biocides.

Pathogenic biofilms formed on the surfaces of implantable medical devices and materials pose an urgent global healthcare problem. Although conventional antibacterial surfaces based on bacteria-repelling or bacteria-killing strategies can delay biofilm formation to some extent, they usually fail in long-term applications, and it remains challenging to eradicate recalcitrant biofilms once they are established and mature. From the viewpoint of microbiology, a promising strategy may be to target the middle stage of biofilm formation including the main biological processes involved in biofilm development.

A Pumpless Microfluidic Neonatal Lung Assist Device for Support of Preterm Neonates in Respiratory Distress.

Premature neonates suffer from respiratory morbidity as their lungs are immature, and current supportive treatment such as mechanical ventilation or extracorporeal membrane oxygenation causes iatrogenic injuries. A non-invasive and biomimetic concept known as the "artificial placenta" (AP) would be beneficial to overcome complications associated with the current respiratory support of preterm infants. Here, a pumpless oxygenator connected to the systemic circulation supports the lung function to relieve respiratory distress.

Dual Pathway for Promotion of Stem Cell Neural Differentiation Mediated by Gold Nanocomposites.

The neural differentiation of embryonic stem cells (ESCs) is of great value in the treatment of neurodegenerative diseases. On the basis of the two related signaling pathways that direct the neural differentiation of ESCs, we used gold nanoparticles (GNP) as a means of combining chemical and physical cues to trigger the neurogenic differentiation of stem cells. Neural differentiation-related functional units (glyco and sulfonate units on glycosaminoglycans, GAG) were anchored on the GNP surface and were then transferred to the cell membrane surface via GNP-membrane interactions.

Precise regulation of particle size of poly(N-isopropylacrylamide) microgels: Measuring chain dimensions with a "molecular ruler".

Hypothesis: Poly(N-isopropylacrylamide) microgels are used extensively in the design of drug carriers, surfaces for control of cell adhesion, and optical devices. Particle size is a key factor and has a significant influence in many areas.

Experiments: In this work, precise control of the particle size of poly(N-isopropylacrylamide) microgels was achieved by controlling the separation distance of the poly(N-isopropylacrylamide) chains.

Modular Polymers as a Platform for Cell Surface Engineering: Promoting Neural Differentiation and Enhancing the Immune Response.

Regulating cell behavior and cell fate are of great significance for basic biological research and cell therapy. Carbohydrates, as the key biomacromolecules, play a crucial role in regulating cell behavior. Herein, "modular" glycopolymers were synthesized by reversible addition-fragmentation chain transfer polymerization.

Rapid antibacterial effect of sunlight-exposed silicon nanowire arrays modified with Au/Ag alloy nanoparticles.

The continuing emergence of antibiotic-resistant bacteria due to the excessive use of antibiotics has produced a strong demand for novel strategies and new materials that do not lead to bacterial resistance. In the present work silicon nanowire arrays modified with gold-silver alloy nanoparticles (SN-Au/Ag) was investigated as a photo-induced antibacterial material. It was shown that SN-Au/Ag can kill bacteria with high efficiency under sunlight in times of the order of a few minutes, and this is achieved through synergism between photothermal and photocatalytic effects.

An ultra-thin, all PDMS-based microfluidic lung assist device with high oxygenation capacity.

Preterm neonates with immature lungs require a lung assist device (LAD) to maintain oxygen saturation at normal levels. Over the last decade, microfluidic blood oxygenators have attracted considerable interest due to their ability to incorporate unique biomimetic design and to oxygenate in a physiologically relevant manner. Polydimethylsiloxane (PDMS) has become the main material choice for these kinds of devices due to its high gas permeability.

The blood compatibility challenge. Part 2: Protein adsorption phenomena governing blood reactivity.

The adsorption of proteins is the initiating event in the processes occurring when blood contacts a "foreign" surface in a medical device, leading inevitably to thrombus formation. Knowledge of protein adsorption in this context has accumulated over many years but remains fragmentary and incomplete. Moreover, the significance and relevance of the information for blood compatibility are not entirely agreed upon in the biomaterials research community.

An artificial placenta type microfluidic blood oxygenator with double-sided gas transfer microchannels and its integration as a neonatal lung assist device.

Preterm neonates suffering from respiratory distress syndrome require assistive support in the form of mechanical ventilation or extracorporeal membrane oxygenation, which may lead to long-term complications or even death. Here, we describe a high performance artificial placenta type microfluidic oxygenator, termed as a double-sided single oxygenator unit (dsSOU), which combines microwire stainless-steel mesh reinforced gas permeable membranes on both sides of a microchannel network, thereby significantly reducing the diffusional resistance to oxygen uptake as compared to the previous single-sided oxygenator designs. The new oxygenator is designed to be operated in a pumpless manner, perfused solely due to the arterio-venous pressure difference in a neonate and oxygenate blood through exposure directly to ambient atmosphere without any air or oxygen pumping.

One-step preparation of gold nanovectors using folate modified polyethylenimine and their use in target-specific gene transfection.

Gene transfection, as an effective treatment for inherited and acquired life threatening diseases caused by genetic deficiencies and abnormalities, has evolved as a promising therapeutic strategy for cancer and other intractable diseases. Non-target-specific vectors will affect normal cells as well as pathogenic cells, resulting in a relative decrease in transfection efficiency and unnecessary cytotoxicity. In the present work, gold nanoparticles (AuNPs) functionalized with folate (FA)-modified polyethylenimine (PEI-FA) were prepared by a single step method (without additional reducing agent) for targeted gene transfection in tumor cells.

BloodSurf 2017: News from the blood-biomaterial frontier.

From stents and large-diameter vascular grafts, to mechanical heart valves and blood pumps, blood-contacting devices are enjoying significant clinical success owing to the application of systemic antiplatelet and anticoagulation therapies. On the contrary, research into material and device hemocompatibility aimed at alleviating the need for systemic therapies has suffered a decline. This research area is undergoing a renaissance fueled by recent fundamental insights into coagulation and inflammation that are offering new avenues of investigation, the growing recognition of the limitations facing existing therapeutic approaches, and the severity of the cardiovascular disorders epidemic.

An ultra-thin highly flexible microfluidic device for blood oxygenation.

Many neonates who are born premature suffer from respiratory distress syndrome (RDS) for which mechanical ventilation and an extracorporeal membrane oxygenation (ECMO) device are used in treatment. However, the use of these invasive techniques results in higher risk of complications like bronchopulmonary dysplasia or requires surgery to gain vascular access. An alternative biomimetic approach is to use the umbilical cord as a vascular access and to connect a passive device to the baby that functions like a placenta.

Sulfonate Groups and Saccharides as Essential Structural Elements in Heparin-Mimicking Polymers Used as Surface Modifiers: Optimization of Relative Contents for Antithrombogenic Properties.

Blood compatibility is a long sought-after goal in biomaterials research, but remains an elusive one, and in spite of extensive work in this area, there is still no definitive information on the relationship between material properties and blood responses such as coagulation and thrombus formation. Materials modified with heparin-mimicking polymers have shown promise and indeed may be seen as comparable to materials modified with heparin itself. In this work, heparin was conceptualized as consisting of two major structural elements: saccharide- and sulfonate-containing units, and polymers based on this concept were developed.

"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.

A multifunctional surface for blood contact with fibrinolytic activity, ability to promote endothelial cell adhesion and inhibit smooth muscle cell adhesion.

Blood compatible materials are required for a wide variety of medical devices. Despite many years of intensive effort, however, the blood compatibility problem, in particular the ability to prevent thrombosis, remains unsolved. Based on the knowledge that the vascular endothelium, the ultimate blood contacting surface, draws on several mechanisms to maintain blood fluidity, it seems reasonable that analogous multifunctionality should be the goal for blood compatible biomaterials.

Stirred, shaken, or stagnant: What goes on at the blood-biomaterial interface.

There is a widely recognized need to improve the performance of vascular implants and external medical devices that come into contact with blood by reducing adverse reactions they cause, such as thrombosis and inflammation. These reactions lead to major adverse cardiovascular events such as heart attacks and strokes. Currently, they are managed therapeutically.

Lipoprotein interactions with a polyurethane and a polyethylene oxide-modified polyurethane at the plasma-material interface.

Lipoproteins [high density lipoprotein (HDL), low density lipoprotein (LDL), and very low density lipoprotein (VLDL)] are present in blood in relatively high concentrations, and, given their importance in cardiovascular disease, the interactions of these species with blood contacting biomaterials and their possible role in thrombogenesis is of interest. In the present communication, quantitative data on the adsorption of apolipoprotein AI, apolipoprotein AII (the main protein components of HDL), and apolipoprotein B (the main protein component of LDL and VLDL), as well as the lipoproteins themselves from plasma to a biomedical grade polyurethane (PU) with and without a copolymer additive that contains polyethylene oxide (PEO) segments, were investigated. Adsorption from some binary solutions was also studied.

Multifunctional nanoparticle-protein conjugates with controllable bioactivity and pH responsiveness.

The modulation of protein activity is of significance for disease therapy, molecular diagnostics, and tissue engineering. Nanoparticles offer a new platform for the preparation of protein conjugates with improved protein properties. In the present work, Escherichia coli (E.

Improvement in the Thermal Stability of Pyrophosphatase by Conjugation to Poly(N-isopropylacrylamide): Application to the Polymerase Chain Reaction.

Polymerase chain reaction (PCR) is a powerful method for nucleic acid amplification. However, the PCR is inhibited in its yield due to its byproduct, pyrophosphate (PPi), a byproduct of the reaction; the yield is thereby limited. The conventional method for hydrolysis of PPi by pyrophosphatase (PPase) is not well adapted for operation at elevated temperatures over long times as required during the PCR.

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.