Creation of biomolecule arrays by electrostatic immobilization on electron-beam-irradiated polystyrene thin films

Abstract

Thin polystyrene films irradiated by an electron beam to create trapped charge are shown to immobilize the positively-charged protein, avidin-fluorescein. Using electron-beam lithography, fluorescent patterns with a minimum feature size of 0.5 µm were formed. The electrostatic nature of the immobilization was supported by the spatial and temporal features of the immobilization process. Additional evidence for an electrostatic mechanism was obtained from experiments to screen the trapped charge density with poly-L-lysine.

Attaching Silica Nanoparticles from Suspension onto Surface Charge Patterns Generated by a Conductive Atomic Force Microscope Tip

“…[9,12] Emissive LC systems have also been used for probing the effect of order on photophysics and energy transfer in organic materials. [13,14] Fluorescence in LC systems has been extensively studied in guest-host systems, in which a non-mesogenic fluorophore is dissolved in a thermotropic LC matrix. [2±5] However, the guest dye typically has limited solubility in the host mesogen, and at high concentrations, often disrupts LC phase formation.…”

“…Due to the smaller size of molecules compared to particles one may expect patterns of higher resolution for the former as demonstrated by Wybourne et al for charged protein molecules attached to electron-beam-charged polymer surfaces. [14] To conclude, positive and negative charge patterns with a resolution down to about 100 nm were written into a thin fluorocarbon film by applying voltage pulses of microsecond length and 15±60 V height to a conductive AFM tip. The patterns were used as templates for locally attaching silica beads with diameter 290 nm and 50 nm suspended in an insulating fluorocarbon liquid to form structures with a width down to about 1 lm.…”

Effects of chemically modified nanostructured PLGA on functioning of lung and breast cancer cells

“…Epithelial mammary cell medium (MEpiCM) consisting of basal medium (ScienCell, 7611), mammary epithelial cell growth supplement (MEpiCGS, ScienCell, 7652) and penicillin/streptomycin (ScienCell, 0503) was used to culture HEMpiC. For the MTT assay, the HEMpiC were seeded on the PLGA surfaces at a density of 35,000 cells/cm 2 and cultured under standard cell culture conditions (5% CO 2 , humidified air at 37°C). After one day, viable cell numbers were determined using the CellTiter 96 nonradioactive cell proliferation assay as previously described.…”

“…1 For example, polystyrene films irradiated by an electron beam have been shown to trap charges useful for immobilizing a positively charged protein, ie, avidin-fluorescein, via electrostatic attraction. 2 Similarly, chitosan-coated nanoparticles with a high degree of deacetylation extend protein conformation because of charge repulsion, allowing such nanoparticles to bind more readily to cell membranes than other conformations of chitosan, such as the coiled conformation, which has less deacetylation. Because of this altered protein conformation, uptake of chitosan nanoparticles by A549 cells increases with increasing deacetylation.…”

Persistent microscopic charge patterns in amorphous silicon thin films for guided assembly of colloids

“…Here, guidance of the assembly by electrostatic forces proved suitable for maskless, rapid, and parallel processing. On dielectric surfaces charge patterns could be produced by steel needles [8], metalized microstamps [9], electron [10] or ion beam [11] irradiation, and by applying voltages to atomic force microscopy (AFM) tips [12]. Exposing the charged films to liquid or gaseous particle dispersions then gave rise to electrostatically controlled assembly of the designed structures.…”