silicon and benzeneboronic-acid

Stimuli-responsive biointerfaces can serve as dynamic tools for modulation of biointerfacial interactions. Considering the complexity of biological environments, surfaces with multistimulus responsive switchable bioactivity are of great interest. In the work reported herein, a multistimulus responsive biointerface with on-off switchable bioadhesion (protein adsorption, bacterial adhesion, and cell adhesion) and surface functions in response to change in temperature, pH, or sugar content is developed. This surface is based on a silicon modified with a copolymer containing a thermoresponsive component (poly(

Topics: Acrylamides; Adsorption; Bacterial Adhesion; Biocompatible Materials; Biotechnology; Boronic Acids; Cell Adhesion; Escherichia coli; HeLa Cells; Humans; Hydrogen-Ion Concentration; Proteins; Silicon; Surface Properties

Phenylboronic acid-derivatized chitosan (chitosan-PBA) were prepared by grafting small molecules bearing phenylboronic acid groups onto chitosan with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) as a coupling reagent pair. Self-assembly multilayer thin films of chitosan-PBA and poly(vinyl alcohol) were subsequently produced under pH control on supporting surfaces, either a silicon wafer or polystyrene latex particles. The driving force of the self-assembly was the ester formation of phenylboronic acid containing polymers with PVA, which can be "turned off" by simple pH control.

Topics: Adhesives; Boronic Acids; Carbodiimides; Chitosan; Hydrogen-Ion Concentration; Latex; Methylamines; Models, Molecular; Molecular Conformation; Polystyrenes; Polyvinyl Alcohol; Silicon; Succinimides; Surface Properties

Artificial stimuli-responsive surfaces that can mimic the dynamic function of living systems have attracted much attention. However, there exist few artificial systems capable of responding to dual- or multistimulation as the natural system does. Herein, we synthesize a pH and glucose dual-responsive surface by grafting poly(acrylamidophenylboronic acid) (polyAAPBA) brush from aligned silicon nanowire (SiNW) array. The as-prepared surface can reversibly capture and release targeted cancer cells by precisely controlling pH and glucose concentration, exhibiting dual-responsive AND logic. In the presence of 70 mM glucose, the surface is pH responsive, which can vary from a cell-adhesive state to a cell-repulsive state by changing the pH from 6.8 to 7.8. While keeping the pH at 7.8, the surface becomes glucose responsive--capturing cells in the absence of glucose and releasing cells by adding 70 mM glucose. Through simultaneously changing the pH and glucose concentration from pH 6.8/0 mM glucose to pH 7.8/70 mM glucose, the surface is dual responsive with the capability to switch between cell capture and release for at least 5 cycles. The cell capture and release process on this dual-responsive surface is noninvasive with cell viability higher than 95%. Moreover, topographical interaction between the aligned SiNW array and cell protrusions greatly amplifies the responsiveness and accelerates the response rate of the dual-responsive surface between cell capture and release. The responsive mechanism of the dual-responsive surface is systematically studied using a quartz crystal microbalance, which shows that the competitive binding between polyAAPBA/sialic acid and polyAAPBA/glucose contributes to the dual response. Such dual-responsive surface can significantly impact biomedical and biological applications including cell-based diagnostics, in vivo drug delivery, etc.

Topics: Acrylamides; Boronic Acids; Glucose; Humans; Hydrogen-Ion Concentration; MCF-7 Cells; Molecular Structure; Nanowires; Particle Size; Silicon; Surface Properties

A smart copolymer film that is sensitive to nucleotide species in solution was developed. The film exhibits ann excellent reversible wettability response to nucleotide solutions, which is accompanied by a phase change and the corresponding swell and shrinkage of the copolymer.

Topics: Acrylamides; Acrylic Resins; Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Boronic Acids; Hydrophobic and Hydrophilic Interactions; Microscopy, Atomic Force; Nucleotides; Phenylthiourea; Polymers; Silicon; Solutions; Surface Properties; Wettability

Nonporous, microparticulate, monodisperse silicas with particle diameters between 0.7 and 2.1 microns are introduced as stationary phases in high-performance affinity chromatography. The immobilization of m-aminophenylboronic acid, p-aminobenzamidine, tri-L-alanine, and concanavalin A onto these silicas was successfully achieved using 3-isothiocyanatopropyl-triethoxysilane as an activation reagent. Immobilized phenylboronic acid was applied to the isolation of nucleosides, nucleotides, and glycoprotein hormones such as bovine follicotropin and human chorionic gonadotropin, while immobilized benzamidine was employed for the isolation of the serine proteases thrombin and trypsin, immobilized tri-L-alanine for the separation of pig pancreatic elastase and human leukocyte elastase, and immobilized concanavalin A for the isolation of horseradish peroxidase. In all affinity chromatographic systems studied, the nonporous monodisperse silicas showed improved chromatographic performance compared to results obtained with porous silica supports using identical activation and immobilization procedures. Furthermore, frontal analysis was used as a method to evaluate the influence of experimental parameters on biological activity and accessible ligand densities. Only minor changes in bioactivity were found with the nonporous affinity supports, where accessibilities were typically higher than ca. 60%. The immobilization of affinity ligands onto porous supports as used in this and associated papers thus represents a successful general procedure for the preparation of stable matrices with fast kinetics for use in high-performance affinity chromatography.

Topics: Alanine; Amidines; Benzamidines; Boronic Acids; Chromatography, High Pressure Liquid; Concanavalin A; Electrophoresis, Polyacrylamide Gel; Indicators and Reagents; Isothiocyanates; Kallikreins; Ligands; Microspheres; Plasminogen; Silanes; Silicon; Silicon Dioxide; Thrombin

The bile-salt-dependent lipase from human milk, which catalyzes the hydrolysis of the water-soluble substrate 4-nitrophenyl acetate and the water-insoluble substrate tributyrin, is competitively inhibited by phenyl boronic acid. This inhibitor does not interfere with the interaction of lipase either with the siliconized glass beads/water interface or with the activator bile-salt binding site. The boronic acid binds near or at the active site serine, since modification of this residue by diisopropylphosphofluoridate (DFP) was prevented by phenyl boronic acid. Phenyl boronic acid binds 15-fold as tightly to bile-salt-dependent lipase as does 4-nitrophenyl acetate. Therefore, phenyl boronic acid bears analogy to a substrate rather than to a tetrahedral intermediate analog. Bile salts such as sodium taurocholate which are non-essential activators for the milk lipase activity on water-soluble substrates decrease the Km as well as the enzyme inhibitor dissociation constant (Ki). They have a slight effect on kcat. These results are interpreted in terms of an increase of the stability of the enzyme-substrate tetrahedral intermediate and in general of any transition states for the formation and for the decomposition of these intermediates upon the enzyme bile salts interaction.

Topics: Adsorption; Binding Sites; Boronic Acids; Glass; Humans; Hydrogen-Ion Concentration; Isoflurophate; Kinetics; Lipase; Milk, Human; Nitrophenols; Silicon; Sterol Esterase; Taurocholic Acid; Triglycerides