Final answer:
Liposomes initially did not work against diseases as hoped mainly because immune system phagocytes removed them from the bloodstream. Advances in biomedicine have since improved liposome functionality for targeted drug delivery. Option 1 is correct answer.
Step-by-step explanation:
Liposomes were initially met with enthusiasm due to their cell-like behavior and the potential for custom-designed drug delivery. Unfortunately, several issues limited their effectiveness against diseases.
One of the primary reasons liposomes did not work as hoped when they were first tried was because immune system phagocytes, such as macrophages, identified and removed them from the bloodstream before they could exert an effect. This process, phagocytosis, involves the immune cells engulfing and then digesting the liposomes with hydrolytic enzymes in lysosomes, preventing the liposomes from reaching their targets.
Other factors that contributed to the limited success of liposomes in disease treatment included degradation in the bloodstream due to enzymes, leakage of the contents before reaching the target, incorrect targeting, and issues with osmotic expansion leading to lysis.
The complexities of the immune system, the physicochemical properties of the therapeutic molecules, and the lipid bilayer's selective permeability further exacerbated these problems. However, advancements in nanotechnology and biomedicine have since improved the design and functionality of liposomes for targeted drug delivery and imaging, overcoming some of these hurdles.