Tuning Microbial Activity via Programmatic Alteration of Cell/Substrate Interfaces.

A wide portfolio of advanced programmable materials and structures has been developed for biological applications in the last two decades. Particularly, due to their unique properties, semiconducting materials have been utilized in areas of biocomputing, implantable electronics, and healthcare. As a new concept of such programmable material design, biointerfaces based on inorganic semiconducting materials as substrates introduce unconventional paths for bioinformatics and biosensing. In particular, understanding how the properties of a substrate can alter microbial biofilm behavior enables researchers to better characterize and thus create programmable biointerfaces with necessary characteristics on demand. Herein, the current status of advanced microorganism-inorganic biointerfaces is summarized along with types of responses that can be observed in such hybrid systems. This work identifies promising inorganic material types along with target microorganisms that will be critical for future research on programmable biointerfacial structures.

Fabrication of ordered metallic and magnetic heterostructured DNA-Nanoparticle hybrids.

Here we provide a method based on enzymatically catalyzed reactions to cleave and ligate DNA molecules coated with nanoparticles to fabricate multi-component structures. This is done by simultaneously digesting two solutions of nanoparticle coated DNA, one with iron oxide particles the other gold particles, which yields short DNA fragments with complementary single stranded overhangs. When added together and re-attached using ligase enzymes multi-component nanoparticle coated structures are formed providing a novel method to fabricate complicated nanoparticle arrangements from the bottom up. We evaluated the fabrication by characterizing the samples with gel electrophoresis and magnetic force microscopy (MFM). The electrophoresis provides proof that the coated DNA molecules were digested with restriction enzymes and ligated by the T4 ligase enzymes. MFM experiments allow us to visualize the multi-component strands and analyze the magnetic versus metallic segments.

Elastomeric nanoparticle composites covalently bound to Al2O3/GaAs surfaces.

This article reports the modification of Al2O3/GaAs surfaces with multifunctional soft materials. Siloxane elastomers were covalently bound to dopamine-modified Al2O3/GaAs semiconductor surfaces using MPt (M = Fe, Ni) nanoparticles. The sizes of the monodisperse FePt and NiPt nanoparticles were less than 5 nm. The surfaces of the nanoparticles as well as the Al2O3/GaAs substrates were modified with allyl-functionalized dopamine that utilized a dihydroxy group as a strong ligand. The immobilization of the elastomers was performed via a hydrosilation reaction of the allyl-functionalized dopamines with the siloxane backbones. X-ray photoelectron spectroscopy (XPS) experiments confirmed the covalent bonding of the siloxane elastomers to the oxide layer on the semiconductor surface. Fourier transform-infrared reflection absorption spectroscopy (FT-IRRAS) measurements revealed that the allyl functional groups are bonded to the siloxane backbones. The FT-IRRAS data also showed that the density of the allyl groups on the surface was lower than that of the siloxane backbones. The mechanical properties of the surface-bound nanocomposites were tested using nanoindentation experiments. The nanoindentation data showed that the soft matrix composed of the elastomeric coating on the surfaces behaves differently from the inner, hard Al2O3/GaAs substrate.