Electrochemical modelling of QD-phospholipid interactions

• The phospholipid activity of thioglycollic acid (TGA) coated QDs is pH dependent.
• The activity is related to particle aggregation coupled to QD surface charge.
• Capping the QDs with CdS/ZnS lowers their phospholipid monolayer activity.

HypothesisThe aggregation of quantum dots (QDs) and capping of individual QDs affects their activity towards biomembrane models.ExperimentsElectrochemical methods using a phospholipid layer on mercury (Hg) membrane model have been used to determine the phospholipid monolayer activity of thioglycollic acid (TGA) coated quantum dots (QDs) as an indicator of biomembrane activity. The particles were characterised for size and charge.FindingsThe activity of the QDs towards dioleoyl phosphatidylcholine (DOPC) monolayers is pH dependent, and is most active at pH 8.2 within the pH range 8.2–6.5 examined in this work. This pH dependent activity is the result of increased particle aggregation coupled to decreasing surface charge emanating from the TGA carboxylic groups employed to stabilize the QD dispersion in aqueous media. Capping the QDs with CdS/ZnS lowers the particles’ activity to phospholipid monolayers.

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