A nano-solution to global water problem: Nanomembranes could filter bacteria
BUFFALO, N.Y. -- New nanomaterials research from the University at Buffalo could lead to new solutions for an age-old public health problem: how to separate bacteria from drinking water.
To the naked eye, both water molecules and germs are invisible -- objects so tiny they are measured by the nanometer, a unit of length about 100,000 times thinner than the width of a human hair.
But at the microscopic level, the two actually differ greatly in size. A single water molecule is less than a nanometer wide, while some of the most diminutive bacteria are a couple hundred.
Working with a special kind of polymer called a block copolymer, a UB research team has synthesized a new kind of nanomembrane containing pores about 55 nanometers in diameter -- large enough for water to slip through easily, but too small for bacteria.
The pore size is the largest anyone has achieved to date using block copolymers, which possess special properties that ensure pores will be evenly spaced, said Javid Rzayev, the UB chemist who led the study.
When many block copolymers are mixed together, their mutual repulsion leads them to assemble in a regular, alternating pattern. The result of that process, called self-assembly, is a solid nanomembrane comprising two different kinds of polymers.
To create evenly spaced pores in the material, Rzayev and colleagues simply removed one of the polymers. The pores' relatively large size was due to the unique architecture of the original block copolymers, which were made from bottle-brush molecules that resemble round hair brushes, with molecular "bristles" protruding all the way around a molecular backbone.
The research on nanomembranes is part of a larger suite of studies Rzayev is conducting on bottle-brush molecules using a National Science Foundation CAREER award, the foundation's most prestigious award for junior investigators. His other work includes the fabrication of organic nanotubes for drug delivery, and the assembly of layered, bottle-brush polymers that reflect visible light like the wings of a butterfly do.
The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system and its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.
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