Spider silk is pretty amazing stuff. Pound for pound, it has a tensile strength close to that of steel while being one-fifth as dense, it's tougher than Kevlar, and it can stretch to almost one-and-a-half times its length without breaking. As if that wasn't enough, it now appears that a genetically engineered version of the substance could be used for delivering genes into human cells.

In the experimental field of gene therapy, therapeutic genes are transported to problematic cells, the genes of which they then alter to perform normally. Viruses are typically used to carry the therapeutic genes within the body, although concerns have been raised regarding the safety of doing so.

Silk proteins, on the other hand, have been used in the field of medicine for decades, and are biocompatible.

A team of scientists led by Tufts University's Prof. David Kaplan has modified spider silk proteins to attach only to diseased cells, and to contain a gene that codes for the protein that causes fireflies to glow. In lab tests on mice containing human breast cancer cells, the silk proteins attached themselves to those cells and injected the glow-producing genes' DNA material into them, without harming the mice. Using special equipment, the researchers were able to detect the glow, which let them know that the proteins had reached their targets.

The research was recently published in the journal Bioconjugate Chemistry.