RESUMO
Three-dimensional (3D) printing has been a very active area of research and development due to its capability to produce 3D objects by design. Miniaturization and improvement of spatial resolution are major challenges in current 3D printing technology development. This work reports advances in miniaturizing 3D printing to the nanometer scale using scanning probe microscopy in conjunction with local material delivery. Using polyelectrolyte polymers and complexes, we have demonstrated the concept of layer-by-layer nanoprinting by design. Nanometer precision is achieved in all three dimensions, as well as in interlayer registry. The approach enables production of designed functional 3D materials with nanometer resolution and, as such, creates a platform for conducting scientific research in designed 3D nanoenvironments as well. In doing so, it enables production of nanomaterials and scaffolds for photonics devices, biomedicine, and tissue engineering.
RESUMO
A direct, head-to-head comparison of the efficacy of a zwitterionic versus a poly(ethylene glycol), PEG, coating in preventing protein adsorption to silica and aggregation of silica nanoparticles is presented. The same siloxane coupling chemistry was employed to yield surfaces with similar coverages of both types of ligand. Nanoparticle and planar surfaces were challenged with salt, serum, lysozyme, and serum albumin at 25 and 37 °C. While both types of surface modification are highly effective in preventing protein adsorption and nanoparticle aggregation, the zwitterion provided monolayer-type coverage with minimal thickness, whereas the PEG appeared to yield a more three-dimensional coating. The mechanism for adsorption resistance is thought to be based on preventing ion pairing between protein and surface charges, which releases counterions and water molecules, an entropic driving force enough to overcome a disfavored enthalpy of adsorption.