Microsponges derived from seaweed are a key component of a tiny programmable chip designed to sniff out diseases such as HIV and cancer.
The microsponges are 280-micrometer beads of agarose, a cheap, common, lab-friendly material made from seaweed and often used as a matrix for growing live cells or capturing proteins.
“We create an ultrahigh-surface-area microsponge that collects a large amount of material,” says John McDevitt, a professor in bioengineering and chemistry at Rice University. “The sponge is like a jellyfish with tentacles that capture the biomarkers.”
The technology is the focus of six human clinical trials. Details of the work are reported in the journal Small.
The agarose bead is engineered to become invisible in water. “That makes it an ideal environment to capture biomarkers, because the matrix doesn’t get in the way of visualizing the contents. This is a nice use of novel biomaterials that are cheap as dirt, yet yield powerful performance,” McDevitt says.
The beauty of agarose is its ability to capture a wide range of targets from relatively huge protein biomarkers to tiny drug metabolites. In the lab, agarose starts as a powder, like Jell-O. When mixed with hot water, it can be formed into gels or solids of any size. The size of the pores and channels in agarose can be tuned down to the nanoscale.
The chips—called programmable bio-nano-chips, or PBNCs— capture biomarkers found in blood, saliva, and other bodily fluids. The biomarkers are sequestered in the tiny sponges set into an array of inverted pyramid-shaped funnels in the microprocessor heart of the credit card-sized PBNC.