🩸 Synthetic Blood: Oxygen Carrier Lab

About this simulation

This is a cutaway of a small blood vessel, oxygenated at the left ("lung") end and delivering oxygen at the right ("tissue") end. Particles flowing through the tube represent whichever oxygen carrier you select, colour-coded from bright red (fully oxygen-loaded) to blue-violet (oxygen released). The physics driving each carrier's colour change is a simplified version of its real oxygen-binding curve.

How it works

• Red blood cells — haemoglobin inside the cell binds oxygen cooperatively (a sigmoidal curve), so it holds tightly at high pO₂ but releases sharply once tissue pO₂ drops, matching metabolic demand.
• HBOCs — cell-free haemoglobin, often chemically cross-linked or polymerised so it isn't filtered by the kidneys. Outside the red-cell membrane it loses cooperative binding and typically shows very high oxygen affinity, so it can hang on to oxygen too tightly to unload efficiently at the tissue. It is also small enough to leak through the vessel wall and scavenge nitric oxide, the molecule that keeps small vessels relaxed — this is the leading reason large HBOC trials were halted after signals of vasoconstriction and heart attacks.
• PFCs — perfluorocarbon droplets don't bind oxygen chemically at all; they simply dissolve it in proportion to the partial pressure (Henry's law), which is why patients receiving PFC emulsions must breathe close to 100% oxygen for the carrier to transport a clinically useful amount.

Controls

• Carrier type — switch between native red cells, an HBOC and a PFC emulsion.
• Tissue pO₂ — the oxygen tension at the delivery end; lower values simulate more oxygen-hungry or poorly perfused tissue.
• Blood flow rate — how fast carriers move through the vessel.
• Show NO-scavenging / extravasation — visualises the real safety concern with free haemoglobin: particles leaking into the vessel wall and the vessel narrowing as nitric oxide is mopped up.

Did you know?

Every haemoglobin-based oxygen carrier tested in large US trials through the 2000s was eventually withdrawn or halted after meta-analyses linked them to increased risk of myocardial infarction and death — a cautionary tale in encapsulation engineering that still shapes how newer carriers are designed today.