Fig 1.
Schematic of the in vitro surfactant exposure set-up.
Aerosol exposed surfactant was generated using a syringe containing BLES connected directly to an EC device which allowed aerosol to be drawn into the syringe and, after 30 seconds, expelled. This procedure was repeated 30 times.
Fig 2.
Vehicle compression/expansion.
BLES exposed to vehicle (■) compared to air control (○). A. Representative surface tension vs area isotherm at the fifth compression/expansion cycle. B. Representative surface tension vs area isotherm at the tenth compression/expansion cycle. C. Minimum surface tensions across 20 compression/expansion cycles. D. Maximum surface tensions across 20 compression/expansion cycles. *P<0.05 compared to air control.
Table 1.
Adsorption and compression data.
Fig 3.
Minimum surface tensions of experimental variables.
Minimum surface tensions (± SEM) across 20 compression/expansion cycles for BLES exposed to three experimental variables, compared to air control. A. Three different vehicle compositions with increasing VG content. B. Three different EC devices. C. Three different wattages set on a programmable EC to alter aerosol temperature. D. BLES mixed with three different volumes of vehicle e-liquid. N = 3 *P<0.05 compared to air control.
Fig 4.
Minimum surface tensions of flavoured e-liquids.
BLES exposed to aerosols containing nicotine and/or flavouring additives compared to air control and unflavoured vehicle at the fifth compression/expansion cycle (± SEM). Each flavour on the x-axis represents BLES exposed to air, unflavoured vehicle, and vehicle + flavouring aerosols. N = 3–4 *P<0.05 compared to air control, #P<0.05 compared to vehicle.
Fig 5.
Menthol compression/expansion data.
BLES exposed to menthol flavoured aerosol (▲) compared to vehicle (■) and air control (○). A. Representative surface tension vs area isotherm at the fifth compression/expansion cycle. B. Representative surface tension vs area isotherm at the tenth compression/expansion cycle. C. Minimum surface tensions (± SEM) across 20 compression/expansion cycles. D. Maximum surface tensions (± SEM) across 20 compression/expansion cycles. (N = 5) *P<0.05 compared to air control, #P<0.05 compared to vehicle.
Fig 6.
Red wedding compression/expansion data.
BLES exposed to red wedding flavoured aerosol (▲) compared to vehicle (■) and air control (○). A. Representative surface tension vs area isotherm at the fifth compression/expansion cycle. B. Representative surface tension vs area isotherm at the tenth compression/expansion cycle. C. Minimum surface tensions (± SEM) across 20 compression/expansion cycles. D. Maximum surface tensions (± SEM) across 20 compression/expansion cycles. (N = 3) *P<0.05 compared to air control, #P<0.05 compared to vehicle.