Hydrogel soft contact lenses can be employed as potential ocular drug delivery carriers due to their excellent comfort, long drug retention duration, and bioavailability (approximately 50%). We employ contact lenses as carriers as a result.
In the beginning, we thought about using adhesins to anchor Escherichia coli on the surface of contact lenses, then covering the outside with a layer of nanofiltration membrane to let salidroside pass through and prevent bacterial leakage. The issue with this strategy is the leaking of small molecule nutrients and metabolic waste. It is challenging to change the membrane to distinguish salidroside only through physical and chemical features because of their distinct compositions.
Fig.1 Initial Plan
Therefore, we have designed the second version of the plan. We built huge vesicles packed with salidroside transport proteins to trap metabolic waste and culture chemicals in contact lenses, allowing only the release of salidroside. Then, we coated the vesicles containing Escherichia coli and culture medium onto the contact lenses. We also attached a layer of nanofiltration membrane on the outer side of the contact lenses to prevent vesicles leakage.
Fig.2 Final Plan
We use liposomes as our vesicles. To prepare liposomes, we first dissolved phosphatidylcholine and cholesterol in chloroform in a round-bottomed flask and then used a rotary evaporator to slowly remove the organic solvent to form a very thin film of dry lipid on the inner surface of the flask. Then, we slowly hydrated the dried lipid membrane with PBS and water or LB liquid medium with E.coli in it to prepare heterogeneous suspensions of liposomes of different sizes by spinning the flask at atmospheric pressure and 50℃. Once we got the liposomes, we characterized them with dynamic light scattering and optical microscopy[1][2].
To permanently cover the entire vesicle containing engineering bacteria onto the soft contact lens, soak the contact lens in a lipid solution for roughly an hour[3].
Fig.3 Contact lenses loaded with vesicles