Kurzweil and Freitas have a differing view.
Kurzweil: Humans and nanomachines will be permanently and seamlessly integrated at the cellular level.
Freitas: Humans and nanomachines will not be integrated. Humans will periodically inject themselves with nanomachines to perform specific purposes meant to restore or upgrade their organic tissue, but the nanomachines will leave the body once that is done.
Reminder – DNA nanoscale devices that have Sensors, Logic and Actuators to deliver drugs when conditions are met ALREADY Exist
A DNA sensor is binded to a protein ligand.
Abstract – We describe an autonomous DNA nanorobot capable of transporting molecular payloads to cells, sensing cell surface inputs for conditional, triggered activation, and reconfiguring its structure for payload delivery. The device can be loaded with a variety of materials in a highly organized fashion and is controlled by an aptamer-encoded logic gate, enabling it to respond to a wide array of cues. We implemented several different logical AND gates and demonstrate their efficacy in selective regulation of nanorobot function. As a proof of principle, nanorobots loaded with combinations of antibody fragments were used in two different types of cell-signaling stimulation in tissue culture. Our prototype could inspire new designs with different selectivities and biologically active payloads for cell-targeting tasks.
The purple blob is the drug payload inside the molecular bucket with a lid and a molecularly activated lock.
Nanorobot lock designs. (a) Schematic orthographic view of the nanorobot, in which
helices are represented as circles (top domain in blue, bottom domain orange), along with aptamer-based locks (blue, red, orange, & green lines). (b) Sequence-level detail of five lock variants that attach to the right side of the nanorobot (the left locks are similar, but with the attachment sequences swapped). Each lock consists of two DNA oligonucleotides. The first encodes an aptamer (e.g. anti-PDGF, shown in red) and nanorobot domain attachment sequence that is complementary to the nanorobot scaffold. The second strand encodes a sequence that is complementary to the aptamer (green), and a similar attachment sequence. In order to tune the behavior of the lock, variants of the complement strand were synthesized with mismatching (poly-thymine) regions proximal to the nanorobot.