Modulation of cell responses to Ag-(MeO MA-co-OEGMA): Effects of nanoparticle surface hydrophobicity and serum proteins on cellular uptake and toxicity.

Nanoparticle (NP) interactions with cellular systems are influenced by both NP physico-chemical properties and the presence of surface-bound proteins that are adsorbed in biological environments. Here, we characterize cellular responses to silver nanoparticles (AgNPs) functionalized with poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl methacrylate) (poly(MeO MA -co-OEGMA )) brushes with tunable hydrophobicity and explore how these responses are modulated by the presence or absence of serum proteins. Poly(MeO MA -co-OEGMA ) with variable composition (5-10% OEGMA) was fabricated to elicit differential hydrophobicity at 37°C for AgNPs capped with these copolymers.

Tuning reversible cell adhesion to methacrylate-based thermoresponsive polymers: Effects of composition on substrate hydrophobicity and cellular responses.

Thermoresponsive polymer (TRP) cell culture substrates are widely utilized for nonenzymatic, temperature-triggered release of adherent cells. Increasingly, multicomponent TRPs are being developed to facilitate refined control of cell adhesion and detachment, which requires an understanding of the relationships between composition-dependent substrate physicochemical properties and cellular responses. Here, we utilize a homologous series of poly(MEO MA -co-OEGMA ) brushes with variable copolymer ratio (x/y) to explore the effects of substrate hydrophobicity on L-929 fibroblast adhesion, morphology, and temperature-triggered cell detachment.

Effect of Nanoparticle Surface Chemistry on Adsorption and Fluid Phase Partitioning in Aqueous/Toluene and Cellular Systems.

Copolymers of di(ethylene glycol) methyl ether methacrylate (x = MeO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA) display lower critical solution phenomena in aqueous systems that are tunable by the copolymer ratio (x:y), ionic strength, and temperature. These properties enable tuning the hydrophobicity of macromolecular systems by variation of (x:y). For nanoparticles stabilized with these macromolecules, this provides a systematic approach to understanding the impact of surface chemistry, specifically hydrophobicity, on the equilibrium and transport properties of nanomaterials in biphasic systems.

Engineering adhesion to thermoresponsive substrates: effect of polymer composition on liquid-liquid-solid wetting.

Adhesion control in liquid-liquid-solid systems represents a challenge for applications ranging from self-cleaning to biocompatibility of engineered materials. By using responsive polymer chemistry and molecular self-assembly, adhesion at solid/liquid interfaces can be achieved and modulated by external stimuli. Here, we utilize thermosensitive polymeric materials based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x = MEO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA), that is, P(MEO2MAx-co-OEGMAy), to investigate the role of hydrophobicity on the phenomenon of adhesion.

Flexible thermoresponsive nanomembranes at the aqueous-air interface.

A synthetic pathway is described to construct thermoresponsive freestanding nanomembranes at the aqueous-air interface of a pendant drop. Dynamic control of the reaction kinetics allows formation of viscoelastic interfaces supporting anisotropic stresses and mechanical stability, which can be tuned by external stimuli.

Aggregation kinetics and colloidal stability of functionalized nanoparticles.

The functionalization of nanoparticles has primarily been used as a means to impart stability in nanoparticle suspensions. In most cases even the most advanced nanomaterials lose their function should suspensions aggregate and settle, but with the capping agents designed for specific solution chemistries, functionalized nanomaterials generally remain monodisperse in order to maintain their function. The importance of this cannot be underestimated in light of the growing use of functionalized nanomaterials for wide range of applications.

Stimulus-responsive Au@(MeO2MAx-co-OEGMAy) nanoparticles stabilized by non-DLVO interactions: implications of ionic strength and copolymer (x:y) fraction on aggregation kinetics.

Functionalized nanoparticles can assist in stabilizing fluid-fluid interfaces; however, developing and applying the appropriate surface modification presents a challenge because successful application of these nanomaterials for biotechnological, food processing, and environmental applications requires their long-term stability in elevated ionic strength media. This work studies stimulus responsive polymeric materials based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x = MeO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y= OEGMA) which, when grafted to gold nanoparticles, show significant, tunable, colloidal stability. The nanoparticles Au@(MeO2MAx-co-OEGMAy) display tunable, reversible aggregation that is highly dependent on the (x:y) ratio and ionic strength.

Modulation of density and orientation of amphiphilic DNA anchored to phospholipid membranes. I. Supported lipid bilayers.

In the present series of papers, we describe the results of a systematic study on the anchoring of cholesterol-tagged oligonucleotides to phospholipids bilayers followed by membrane-assisted hybridization of the complementary strand in solution. This paper describes the anchoring of novel cholesterol-modified DNA-18mers in supported lipid bilayers (SLB) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine: we compared the behavior of two anchoring functionalities differing in the number of cholesterol units and in the length of a spacer group. Quartz Crystal Microbalance with impedance monitoring (QCM-Z) measurements showed that both oligonucleotides insert into the bilayer membrane through cholesterol anchoring; however, dramatic differences, in terms of surface organization and thickness, are found as the number of anchoring units increases.

Modulation of density and orientation of amphiphilic DNA on phospholipid membranes. II. Vesicles.

In the present series of papers, we describe the results of a systematic study on the anchoring of cholesterol-tagged oligonucleotides to phospholipid bilayers followed by membrane-assisted hybridization of the complementary strand in solution. This paper compares the behavior of two cholesteryl modified oligonucleotides, differing in the architecture and hydrophobicity of the lipophilic moiety, in the self-aggregation, hybridization, and insertion in phospholipid vesicle membranes. We have focused our attention on a singly substituted derivative (SC-ON(1)) and a multicholesterol (MC-ON(1)) derivative, where the cholesteryl units are inserted at the desired positions along a noncoupling T-sequence.

DNA closed nanostructures: a structural and Monte Carlo simulation study.

DNA nanoconstructs are obtained in solution by using six unique 42-mer DNA oligonucleotides, whose sequences have been designed to form a pseudohexagonal structure. The required flexibility is provided by the insertion of two non-base-paired thymines in the middle of each sequence that work as flexible hinges and constitute the corners of the nanostructure when formed. We show that hexagonally shaped nanostructures of about 7 nm diameter and their corresponding linear open constructs are formed by self-assembly of the specifically designed linear oligonucleotides.