Research of Trap and Electron Density Distributions in the Interface of Polyimide/Al2O3 Nanocomposite Films Based on IDC and SAXS

The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.

Oriented Antibody Immobilization and Immunoassay Based on Boronic Acid-containing Polymer Brush

High sensitive immunoassay platforms have gained intense attention due to their vital roles in early-stage disease diagnosis and therapeutic information feedback. Although random covalent-binding of antibody has been widely adopted in immunoassays due to its simplicity and effectiveness, it readily loses its activity and fails to exhibit high antigen-binding capacity. In this work, copolymer of zwitterionic sulfobetaine methacrylate（SBMA） and glycidyl methacrylate（GMA） brushes were immobilized onto inert polypropylene（PP） via surface-initiated atom transfer radical polymerization（ATRP） based on biomimetic dopamine pretreatment. Subsequently, boronic acid（BA） groups were covalently bonded via active GMA units, followed by the introduction of oriented immobilization of antibody. Owing to the oriented immobilization of antibody facilitated by BA groups in polymer brush, the bioactivity of antibody is well preserved, which endows the surface with significantly enhanced antigen-binding capacity. Moreover, the existence of SBMA segments in polymer brushes renders the surface high resistance to nonspecific protein adsorption, significantly alleviating the signal interference of antigen recognition. This strategy could find potential applications in developing high sensitive immunoassay platforms based on the different substrates.

Surface Patterning of Self-healing P(MMA/nBA)Copolymer for Dynamic Control Cell Behaviors

Cell behaviors are regulated by a dynamic and complex environment characterized by biophysical,mechanical and biochemical properties.However,most works regulate cell behaviors under static conditions or by external factors.To control cell adhesion and proliferation with a dynamic and mechanical environment,we pattern the surface on self-healing copolymer P(MMA/nBA).The copolymer P(MMA/nBA)with the composition of 48/52(MMA/nBA)recovers nearly 100%of its original tensile strains after 86 h of recovery from deformation.The physical patterns on P(MMA/nBA)film are obtained over large areas and the size of the hole and the width of connecting bar are in line with the copper grid specifications.The patterned surface tends to be fiat after 12 h with almost 75%-80%recovery.Compared with cell incubation on polystyrene fiat and patterned surface of P(MMA/nBA)film without self-healing capability,the number and morphology of cells are well manipulated on the patterned surface of self-healing P(MMA/nBA)film.This approach provides a convenient method for dynamically regulating the cell behaviors on the surface of self-healing materials without chemical or biological modifications.

A Biomimetic Surface for Infection-resistance through Assembly of Metal-phenolic Networks

Despite the fact that numerous infection-resistant surfaces have been developed to prevent bacterial colonization and biofilm formation, developing a stable, highly antibacterial and easily produced surface remains a technical challenge. As a crucial structural component of biofilm, extracellular DNA（eDNA） can facilitate initial bacterial adhesion, subsequent development, and final maturation. Inspired by the mechanistic pathways of natural enzymes（deoxyribonuclease）, here we report a novel antibacterial surface by employing cerium（Ce（Ⅳ）） ion to mimic theDNA-cleavage ability of natural enzymes. In this process, the coordination chemistry of plant polyphenols and metal ions was exploited to create an in situ metal-phenolic film on substrate surfaces. Tannic acid（TA） works as an essential scaffold and Ce（Ⅳ） ion acts as both a cross-linker and a destructor of eDNA. The Ce（Ⅳ）-TA modified surface exhibited highly enhanced bacteria repellency and biofilm inhibition when compared with those of pristine or Fe（Ⅲ）-TA modified samples. Moreover, the easily produced coatings showed high stability under physiological conditions and had nontoxicity to cells for prolonged periods of time. This as-prepared DNA-cleavage surface presents versatile and promising performances to combat biomaterial-associated infections.

Fouling-resistant Behavior of Liquid-infused Porous Slippery Surfaces

Marine economy is seriously affected by marine biofouling, which has plagued people for thousands of years. Although various strategies have been developed to protect artificial surfaces against marine biofouling, cost-effective biofouling-resistant coating is still a goal in pursue. Herein, a cost-effective liquid-infused porous slippery surface （LIPSS） was facilely prepared by using poly（styrene-b-（ethylene-co-butylene）-b-styrene） （SEBS） elastomer to form microsphere surfaces, followed by infusing fluorocarbon lubricants into the porous structure. The as-prepared slippery surfaces were characterized by static water contact angle, sliding velocity and sliding angle analysis. We also investigated the adhesion behavior of Escherichia coli （E. coli） and limnetic algae on different surfaces. It is confirmed that the slippery surfaces have better anti-biofouling properties than the porous SEBS reference. This cost-effective approach is feasible and easily produced, and may potentially be used as fouling-resistant surfaces.