silicon and acrylic-acid

Luminescent silicon nanocrystals are promising nanomaterials for biomedical applications due to their unique optical properties and biocompatibility. Here, we demonstrate a two-step surface modification approach coupling gas-phase and liquid-phase methods to synthesize PEGylated acrylic acid grafted silicon nanocrystals with near-infrared emission in water and biological media. First, acrylic acid grafted silicon nanocrystals are synthesized by an all-gas-phase approach on a millisecond time scale, omitting high temperature and postpurification processes. Subsequently, room-temperature PEGylation is carried out with these acrylic acid grafted silicon nanocrystals, yielding stable colloidal dispersions in both water and high ionic strength Tyrode's buffer with 20-30 nm hydrodynamic diameters. The PEGylated silicon nanocrystals exhibit photoluminescence in the 650-900 nm near-IR window with quantum yields of ∼30% and ∼13% in deionized water and Tyrode's buffer, respectively, after a 7-day oxidation in water. The surface-functionalized Si NCs exhibit relatively small toxicity to MDA-MB-231 cells at concentrations relevant to bioimaging applications.

Topics: Acrylates; Nanoparticles; Polyethylene Glycols; Silicon; Water

Plasma Enhanced Chemical Vapor Deposition (PECVD) technique is used to polymerize Acrylic Acid for the surface functionalization of porous silicon samples with different pore dimensions. The polymer shows free COOH groups also at the pores inner surface, suitable for the immobilization of fluorescent labeled Protein A. The stability of the polymer, its role in the protection from aging of the porous matrix and the efficiency of the functionalization for the binding of protein A have been characterized by ATR-FTIR, SEM, Optical Contact Angle and Fluorescence Microscopy. The polymerization process is well controllable and suitable for the functionalization of porous silicon leaving free carboxylic groups at the surface ready for the immobilization of biochemical species for sensing applications.

Topics: Acrylates; Biosensing Techniques; Fluorescent Dyes; Immobilized Proteins; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Microscopy, Fluorescence; Plasma Gases; Polymerization; Porosity; Quinolinium Compounds; Silicon; Staphylococcal Protein A; Surface Properties

Si quantum dots (SiQDs) based nanospheres (SiNSs) were prepared via a novel synthetic strategy. These SiNSs were demonstrated to possess unique dot spacing dependent photoluminescence (PL) up-conversion and surface dependent (N modified surface) down-converted PL. It was demonstrated that a small distance between SiQDs (<5 nm) is the necessary condition for the PL up-conversion of SiNSs, while the surface state of SiQDs will affect the maximum emission wavelength and the PL intensity. The as-prepared SiNSs feature excellent aqueous dispersibility, and their optical properties were found to be stable enough in a specified temperature and pH range.

Topics: Acrylates; Ethylenediamines; Hydrogen; Luminescent Measurements; Nanospheres; Quantum Dots; Silicon; Spectroscopy, Fourier Transform Infrared

We report a simple, reliable high-throughput method for patterning passivated silicon with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The approach completely protects silicon from chemical oxidation, provides precise control over the shape and size of the patterned features in the 100 nm domain, and gives rapid, ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules.

Topics: Acrylates; Carboxylic Acids; Catalysis; Hydrolysis; Nanotechnology; Oxidation-Reduction; Polyurethanes; Printing; Reproducibility of Results; Silicon; Succinimides; Surface Properties

To develop the polymeric adsorbent that possess anionic exchangeable function, PP-g-AA-Am fibers were prepared by photoinduced grafting of acrylic acid (AA) onto polypropylene (PP) nonwoven fibers and subsequent conversion of carboxyl group in grafted AA to an amine (Am) group by reaction with diethylene triamine (DETA). The amination of grafted AA increased with increase in the degree of grafting, the reaction time and temperature of the chemical modification process. Catalytic effect of metal chlorides such as AlCl(3) and FeCl(3) on the amination of grafted AA was significant but not essential to lead the amination. FT-IR and solid (13)C NMR data indicate that amine group was introduced into PP-g-AA fiber through amide linkage between grafted AA and DETA. The anion exchange capacity of PP-g-AA-Am fiber increased with increase in the degree of amination, but reached maximum value at about 60% amination of 150% grafted AA. PP-g-AA-Am fiber showed much higher maximum capacity for PO(4)-P and a similar capacity for NO(3)-N compared to commercial anion resins. Furthermore, the PP-g-AA-Am fiber also has adsorption ability for cations because of unaminated residual carboxyl group.

Topics: Absorption; Acrylates; Aluminum Chloride; Aluminum Compounds; Amination; Anion Exchange Resins; Carboxylic Acids; Chlorides; Ferric Compounds; Hydrogen-Ion Concentration; Materials Testing; Polyamines; Polypropylenes; Silicon; Spectroscopy, Fourier Transform Infrared; Surface Properties; Time Factors

Surface chemistry of silicon/glass based bio-MEMS was controlled by depositing plasma polymerized acrylic acid (ppAc) films at two different electrode positions in a two-stage plasma reactor. AFM and XPS were used to characterize the surface roughness and surface chemistry of the films, respectively. The surface of bio-MEMS was highly functionalized with carboxylic/ester functionalities with a very good surface uniformity. The proportion of carbon atoms as C-OX, C(==O)OX functionalities was decreased and an increase in C==O functionalities was observed when the electrode position was increased from the mesh. These functionalized bio-MEMS devices have advantages in fabrication of reusable micro fluidic devices and the variation of fluid velocity by changing the surface properties may be used to develop a micro-mixing system to control the mixing ratio of different fluids for different biological and chemical applications.

Topics: Acrylates; Carbon; Crystallization; Electrochemistry; Electrodes; Equipment Design; Materials Testing; Microfluidics; Nanotechnology; Nanotubes, Carbon; Polymers; Silicon; Spectrometry, X-Ray Emission; Surface Properties; X-Rays