Respirocytes A Mechanical Artificial Red Cell: Exploratory Design in Medical Nanotechnology -Robert A. Freitas Jr.

1. RespirocytesA Mechanical Artificial Red Cell: Exploratory Design in Medical Nanotechnology-Robert A. Freitas Jr. Presented by UmaMaheswari Ethirajan

2. Overview • Introduction • Preliminary Design Issues • Nanotechnological design of Respiratory Gas carriers • Baseline design • Therapeutics • Safety and Bio-compatibility • Applications • Summary and Conclusion

3. Molecular manufacturing processes applications. Medical implications – precise interventions at cellular and molecular levels. Medical nanorobots – research, diagnoses and cure. Preliminary design for artificial mechanical erythrocyte or Red Blood Cell (RBC) – Respirocyte. Introduction

4. Preliminary Design Issues • Biochemistry of respiratory gas transport – oxygen and carbon-dioxide. • Existing Artificial Respiratory Gas carriers • Hemoglobin Formulations • 50% more O2 than natural RBCs. • Dissociates to dimers, Binds to O2 more tightly, Hemoglobin oxidized. • Fluorocarbon Emulsions • Physical solubilization – emulsions of droplets • Shortcomings of Current technologies • Too short life time • Not designed for CO2 transport • vasoconstriction

5. Design of Respiratory Gas carriers • Pressure Vessel • Spherical, Flawless diamond or sapphire • 1000atm – optimal gas molecule packing density • Discharge time very less - <2 minutes • Recharging with O2 from lungs • Respiratory gas equilibrium – more CO2 • Provide additional tankage for CO2 • Means for gas loading and unloading

6. Molecular Sorting Rotors • Binding site pockets – rims – 12 arms • Selective binding • Eject – cam action • Fully reversible – load and unload • 7nm x 14nm x 14nm • 2 x 10-21 kg • Sorts molecules of 20 or fewer atoms • 106 molecules/ sec

7. Molecular Sorting Rotors (cont’d) • Power saving – generator subsystem • 90% occupancy of rotor binding sites • Multi-stage cascade – virtually pure gases

8. Nanotechnological Design of Respiratory Gas carriers (cont’d) • Sorting Rotors binding sites • O2, CO2, Water, Glucose • Device Scaling • On-board computer – 58nm diameter sphere • 37.28% of tank surface – sorting rotors • Reasonable range – 0.2 to 2 microns • Present study assumes – approx. 1 micron • Buoyancy control • Loading and unloading water ballast • Very useful – exfusion from blood • Example – specialized centrifugation apparatus

9. Baseline Design - Power • glucose & oxygen – Mechanical Energy • Glucose – blood & Oxygen – onboard storage • Glucose Engine – 42nm x 42nm x 175nm • Output is water – approx. glucose absorbed • Fuel tank – glucose storage – 42nm x 42nm x 115nm • Mechanical or hydraulic power distribution • Rods & gears • Pipes & valves • Control – onboard computer

10. Baseline Design - Communications • Physician – broadcast signals • Modulated compressive pressure pulses • Mechanical transducers – surface of respirocytes • Transducers – pressure driven actuators • Internal Communication • Hydraulic - Low pressure acoustic spikes • Mechanical - Mechanical rods and couplings

11. Baseline Design - Sensors • Sorting rotors – quantitative molecular concentration sensors • Internal pressure sensors – gas tank loading, ballast and glucose fuel tanks, internal/external temperature sensors.

12. Baseline Design – Onboard Computation • 104 bit/sec computer • 105 bits of internal memory • Gas loading and unloading • Rotor field and ballast tank management • Glucose engine throttling • Power distribution • Interpretation of sensor data • Self-diagnoses and control of protocols

13. Glucose rotor, Tank, Engine and Flue Assembly in 12-station Respirocyte baseline design

14. Pumping Station Layout

15. Equatorial Cutaway View of Respirocyte

16. Polar Cutaway View of Respirocyte

17. Baseline Design – Tank Chamber Design • Diamondoid honeycomb or geodesic grid skeletal framework • Perforated compartment walls • Present design – CO2 and O2 separate • Proposed – same chamber • Disadvs • Respiration control – CO2 level • Reverse CO2 overloading • Reduction of maximum outgassing rate

18. Therapeutics • Minimum Therapeutic dose • Human blood O2 capacity – 8.1 x 1021 molecules • Each respirocyte – 1.51 x 109 O2 molecules • Full duplication – 5.36 x 1012 devices • Hypodermal injection or transfusion • Maximum Augmentation Dose • Fully O2 charged dose – 9.54 x 1014 respirocytes • 12 minutes and peak exertion • 3.8 hours at rest • Control Protocols • Precise external control by physician • Programmable for sophisticated behaviors

19. Safety and Bio-compatibility • Mechanical failure modes • Device overheating • Non-combustive device explosion • Radiation damage • Coagulation • Inflammation • Phagocytes

20. Applications • Transfusions • Treatment of Anemia • Fetal and Child-related disorders • Respiratory Diseases • Cardiovascular and Neurovascular applications • Tumor therapy and Diagnostics • Asphyxia • Underwater breathing • Endurance oriented sport events • Anaerobic and aerobic infections • Veterinary medicine

21. Summary and Conclusion • Artificial erythrocyte • Avoiding carbonic acidity – mechanical transport of CO2 • 236 times more O2 per unit volume than natural RBCs • Tough diamondoid material • Numerous sensors • On-board nano-computer • Remotely programmable • Lifespan of 4 months • Future advances in molecular machine system engineering – actual construction.

22. References • Drexler KE. Nanosystems: Molecular Machinery, Manufacturing, and Computation. New York: John Wiley & Sons, 1992. • www.foresight.org

23. Thank You