Protein-releasing conductive anodized alumina membranes for nerve-interface materials

Nanopillared Chitosan/Gelatin Films: A Biomimetic Approach for Improved Osteogenesis

Biomimicry strategies, inspired from natural organization of living organisms, are being widely used in the design of nanobiomaterials. Particularly, nonlithographic techniques have shown immense potential in the facile fabrication of nanostructured surfaces at large-scale production. Orthopedic biomaterials or coatings possessing extracellular matrix-like nanoscale features induce desirable interactions between the bone tissue and implant surface, also known as osseointegration. In this study, nanopillared chitosan/gelatin (C/G) films were fabricated using nanoporous anodic alumina molds, and their antibacterial properties as well as osteogenesis potential were analyzed by comparing to the flat C/G films and tissue culture polystyrene as controls. In vitro analysis of the expression of RUNX2, osteopontion, and osteocalcin genes for mesenchymal stem cells as well as osteoblast-like Saos-2 cells was found to be increased for the cells grown on nano C/G films, indicating early-stage osteogenic differentiation. Moreover, the mineralization tests (quantitative calcium analysis and alizarin red staining) showed that nanotopography significantly enhanced the mineralization capacity of both cell lines. This work may provide a new perspective of biomimetic surface topography fabrication for orthopedic implant coatings with superior osteogenic differentiation capacity and fast bone regeneration potential.

Nano-Architectural Approaches for Improved Intracortical Interface Technologies

Intracortical microelectrodes (IME) are neural devices that initially were designed to function as neuroscience tools to enable researchers to understand the nervous system. Over the years, technology that aids interfacing with the nervous system has allowed the ability to treat patients with a wide range of neurological injuries and diseases. Despite the substantial success that has been demonstrated using IME in neural interface applications, these implants eventually fail due to loss of quality recording signals. Recent strategies to improve interfacing with the nervous system have been inspired by methods that mimic the native tissue. This review focusses on one strategy in particular, nano-architecture, a term we introduce that encompasses the approach of roughening the surface of the implant. Various nano-architecture approaches have been hypothesized to improve the biocompatibility of IMEs, enhance the recording quality, and increase the longevity of the implant. This review will begin by introducing IME technology and discuss the challenges facing the clinical deployment of IME technology. The biological inspiration of nano-architecture approaches will be explained as well as leading fabrication methods used to create nano-architecture and their limitations. A review of the effects of nano-architecture surfaces on neural cells will be examined, depicting the various cellular responses to these modified surfaces in both in vitro and pre-clinical models. The proposed mechanism elucidating the ability of nano-architectures to influence cellular phenotype will be considered. Finally, the frontiers of next generation nano-architecture IMEs will be identified, with perspective given on the future impact of this interfacing approach.

Fabrication techniques enabling ultrathin nanostructured membranes for separations

The fabrication of nanostructured materials is an area of continuous improvement and innovative techniques that fulfill the demand of many fields of research and development. The continuously decreasing size of the smallest patternable feature has expanded the catalog of methods enabling the fabrication of nanostructured materials. Several of these nanofabrication techniques have sprouted from applications requiring nanoporous membranes such as molecular separations, cell culture, and plasmonics. This review summarizes methods that successfully produce through-pores in ultrathin films exhibiting an approximate pore size to thickness ratio of one, which has been shown to be beneficial due to high permeability and improved separation potential. The material reviewed includes large-area, parallel, and affordable approaches such as self-organizing polymers, nanosphere lithography, anodization, nanoimprint lithography as well as others such as solid phase crystallization and nanosphere lens lithography. The aim of this review is to provide a set of inexpensive fabrication techniques to produce nanostructured materials exhibiting pores ranging from 10 to 350 nm and a pore size to thickness ratio close to one. The fabrication methods described in this work have reported the successful manufacture of nanoporous membranes exhibiting the ideal characteristics to improve selectivity and permeability when applied as separation media in ultrafiltration.