This installment focuses on advanced analytical separations that incorporate nanomaterials for improved chemical selection.
These new nanomaterials are based on bioinspired and polymeric self-assembled aggregates. Capillary electrophoresis and chromatographic
methods were harnessed for the separation of a wide variety of samples. Compelling applications include rapid separations
of 100 DNA fragments and separations of enantiomers, aptamers, small molecules, and glycans. The implementation, performance,
and fundamental properties of these new media are discussed.
The Pittsburgh Conference of Analytical Chemistry and Applied Spectroscopy (Pittcon), was held March 12–18, 2011, at the World
Congress Center in Atlanta, Georgia. The Pittcon 2011 technical program boasted a number of exciting advances in analytical
chemistry, including a number of leading edge technologies in the area of separation science. A session sponsored by the American
Chemical Society's (ACS) Subdivision of Chromatography and Separations Chemistry on self-assembled nanomaterials for enhanced
chemical separations was organized by Professor Lisa Holland of the Department of Chemistry, West Virginia University (Morgantown,
Presentations in this Pittcon session outlined enhanced separations and diverse applications with techniques based on new
materials for thin-layer chromatography (TLC), solid-phase microextraction (SPME), and capillary electrophoresis (CE). Some
separation media discussed in this session emanated from fabrication techniques such as photolithography and chemical vapor
deposition. A new "spin" on fabrication was nanofiber electrospinning. Self-assembly of biomolecules inspired by natural systems
was a prominent theme. Generally, these biological selectors were effective for the separation of biopolymers such as DNA,
aptamers, and glycans, as well as biologically relevant small molecules. Classical self-assembled surfactant micelles were
adapted to improve electrically driven separations.
The purpose of this installment of "Column Watch" is to summarize some of the key techniques presented in this session and
discuss future directions that new self-assembled nanomaterials may take in separation science.
Background in Self-Assembled Nanomaterials for Separation Science
Traditional separation media such as chromatographic packing material or open-tubular chromatography columns are fabricated
through the covalent modification of a polymeric or inorganic (silica, for example) surface. With new advances in material
science, newer strategies arise that result in sophisticated architecture for chemical separations based on molecular self-assembly.
These processes result from spontaneous molecular interactions to control the size, shape, or surface characteristics of the
assembly, often resulting in what is a highly ordered and unique structure. A benefit of this approach is that reduced chemical
modification results in a greatly simplified fabrication protocol of what is a complex final product. Assembled structures
may be made from components that are inorganic or organic (or both) or biological in nature. Frequently, such materials originate
from or are inspired by biological systems, such as cellular membranes. The resulting supramolecular assembly can occur through
a variety of mechanisms such as ionic, hydrophobic, or hydrophilic interactions, as well as adsorption. Although individual
interactions may be weak, the summative force from these interactions stabilizes the entire assembly. These molecular assemblies
may possess nanoscale features as well as unique properties that macroscale materials often lack.