Fig. 1: AALs for on-demand drug uncaging.
a, Ultrasound-sensitive drug nanocarriers release their cargo upon ultrasound activation while they are circulating in the blood pool because sucrose alters the liposome internal buffer acoustic characteristics and osmolarity, increasing interaction with ultrasound, which increases lipid membrane drug permeability, allowing drug release that is accelerated by the osmotic gradient (https://biorender.com/bfnjkwv). b, In vitro ketamine uncaging from ketamine-loaded (KL) liposomes with 0% (KL), 5% (S5-KL) or 10% (S10-KL) added sucrose. Sonication (250 kHz centre frequency, 1.7 MPa estimated in situ peak negative pressure at RT, 25% duty cycle, PRF 5 Hz, 60 s) with more sucrose internally uncaged more drug (n = 9 per group). c, Spontaneous ketamine release from KL, S5-KL and S10-KL with 1 h of 37 °C incubation in plasma or buffer shows 10% additional sucrose yields reduced 37 °C plasma stability (n = 6 per group). d,e, Bar (d) and scatter plots (e) of drug uncaging from liposomes with equiosmolar additional sodium chloride (NaCl5-KL), glucose (Glu5-KL) or sucrose (S5-KL) shows that uncaging performance correlates with internal acoustic impedances differences; r2 = 0.97, P = 0.002 (n = 3 per group) (*P = 0.0129, **P = 0.0017). f, Ultrasonic ketamine uncaging from S5-KL with varying peak negative pressure/MI (250 kHz, 25% duty cycle, PRF 5 Hz, 60 s) at RT or 37 °C (n = 3 per group). g, Stability of S5-KL for drug retention and uncaging across 90 days in 4 °C storage. No observed change in size/PDI by DLS; representative batch size/PDI of 165.8 nm/0.061 at day 1 and 167.7 nm/0.074 at day 90 post production (n = 3 per group). h, Electron microscopy shows spherical shape of the liposomes with primarily unilamellar vesicles and <5% multilamellar vesicles, with particle size decreasing with sonication. No gas elements or voids within the AALs with or without sonication. Scale bars, 100 nm. i–k, Ropivacaine (RL; i), bupivacaine (BL; j) and lidocaine loaded (LL; k) liposomes with or without 5% additional sucrose internally show higher in vitro ultrasonic drug uncaging with sucrose incorporation (n = 3 per group). Data presented as mean ± s.d. of three or more independent experiments. Comparisons between two groups were performed by two-tailed, two-sample Student’s t-test, and that among multiple groups by one-way ANOVA; NS, not significant, *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001.
