© 1999 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999

10.4.2.5.2 Neuter and Release (NR)

After identification and docking, the nanorobot extends an adhesion antenna tool (Section 9.3.2 (2)) into the bacterial interior and sweeps it around inside. The antenna recognizes DNA and RNA material including chromosomes, plasmids, and ribosomes. Any such material found during antenna sweeps through the protoplasm adheres to reversible binding sites on the antenna. The antenna of diameter d_ant is then rotated N_rot ~ L_DNA / p d_ant turns which is sufficient to randomly enspool a chromosome strand of maximum length L_DNA; taking d_ant = 0.1 micron and L_DNA = 1.3 mm for ~4.2 Mb E. coli, N_rot = 4100 turns which probably may be executed in ~1 sec without strand breakage because the bonding between chromosome and cellular matrix is likely noncovalent. The mean thickness of the bolus of DNA that is tightly spooled around the antenna is DX = ((V_DNA / p L_bolus) + (d_ant² / 4))^1/2 (d_ant/2) = 12 nm, where DNA volume V_DNA ~ 4.2 x 10⁶ nm³ at ~1 nm³/bp and L_bolus ~ 1 micron is the bolus length.

The adhesion antenna* is retracted, with patching lipids ejected from the tip as it clears the hole, thus auto-sealing the hole. The adhered genetic material is pushed into a reaction chamber (Section 10.4.2.4.2), whereupon deoxyribonuclease enzymes are introduced to reduce bacterial DNA to nucleotides which are then removed from the solution by molecular sorting rotors and discharged. Ribonucleases and peptidases are also present to reduce RNA and ribosomes to dischargeable effluent, leaving the cell with no genetic or transcription capability, effectively neutering the bacterium. After minor surface modifications to enhance immune system recognition (Section 10.4.1.2), the cell is abandoned to allow natural phagocytic processes to run their course.

* R. Bradbury suggests that a DNA-binding grappling hook mounted on a cable sliding inside a nanotube sheath could be inserted less disruptively through a bacterial cell wall. The interior DNA strands are snagged and then pulled into the nanorobot through the sheath by retracting the cable.

Last updated on 24 February 2003