Effects of acoustic streaming from moderate-intensity pulsed ultrasound for enhancing biofilm mitigation effectiveness of drug-loaded liposomes

Abstract

Because biofilms have resistance to antibiotics, their control using minimum amounts of chemicals and energy becomes a critical issue particularly for resource-constrained long-term space and deep-sea explorations. This preliminary study investigates how ultrasound promoting penetration of antibiotic-loaded liposomes into alginate-based bacterial biofilms, resulting in enhanced bacterial (Ralstonia insidiosa) killing. Nano-sized liposomes are used as a delivery vehicle for the antibiotic gentamicin. Alginate-based synthetic biofilms, which are widely acknowledged as biofilm phantoms, filled with liposome solution are formed at the bottoms of six-well Petri dishes and exposed to ultrasound (frequency = 2.25 MHz, 10% duty cycle, and spatially and temporally averaged intensity ISAPA = 4.4 W/cm(2)). Gentamicin is released from liposomes after they are lysed using detergent solution (0.05% sodium dodecyl sulfate, 1.0% Triton X-100) and incubated for 20 min. The alginate biofilm is dissolved and diluted, counting of colony-forming units shows about 80% of the bacteria are killed. It has also been shown the liposome-capture density by the alginate film increases linearly with the ultrasound intensity up to ISAPA = 6.2 W/cm(2) reaching approximately threefold that without ultrasound. Measurement by using particle-image velocimetry has demonstrated the acoustic streaming with modification by thermal convection controls the enhancement of the liposome capture rate.

Recent Developments in Antibacterial Therapy: Focus on Stimuli-Responsive Drug-Delivery Systems and Therapeutic Nanoparticles

“…In another work [29], the authors showed that the focused US and gentamicin-encapsulated liposomes reduced the number of viable bacteria in alginate-based Ralstonia insidiosa biofilms by approximately 72%, compared to US alone, gentamicin in solution alone (no liposomes) and gentamicin in solution with high-intensity focused US. These data show that high-intensity focused US in combination with an antibiotic strategy can kill bacteria within synthetic alginate biofilms, while non-focused US was able to increase the attachment of liposomes to the biofilm, as demonstrated by the same authors [30].…”

Sonodynamic antimicrobial chemotherapy: An emerging alternative strategy for microbial inactivation

“… 42 kHz, 0.30 W/cm 2 , 15 min. C. albicans In vitro 90%~100% [13] MLP18 20 μM 1.0 MHz, 0.97 W/cm 2 , 5 min E. coli MRSA In vivo (mice) ~60% ~80% [1] CNPs-ICG 1000 μg/mL 1 MHz, 1.56 W/cm 2 , 1 min Biofilm ( P. gingivalis, Prevotella intermedia ) In vitro 57.9% [61] Gentamicin (Nano-sized liposomes) 0.8 mg/mL 2.25 MHz, 4.4 W/cm 2 Ralstonia insidiosa biofilm In vitro 73% [87] Pd@Pt-T790 25 ppm 50 ppm 1.0 MHz, 0.97 W/cm 2 , 50% cycle, 8 min MRSA In vitro In vivo (mice) 1 ~ 5 >6 [73] Fe@UCNP-HMME 4.75 µg 1 W/cm 2 , 10 min 2 W/cm 2 , 10 min E. coli MRSA In vitro 60% 70% [22] UCNP@SiO 2 -RB 125 μg/mL 2 W/cm 2 , 10 min E. coli MRSA In vitro 70% 70% [23] UCNP@mSiO 2 (RB)-AgNPs 45 µg/mL 2 W/cm 2 , 10 min MRSA In vitro 5 [88] NM@Cur 50 mM 1.56 W/cm 2 , 1 min S. mutans In vitro 99.9% (~6 log) [75] Xanthene dye ...…”

Using Acoustic Fields to Fabricate ECM-Based Biomaterials for Regenerative Medicine Applications

“…In experimental and simulation studies of streaming within cylindrical wells, such as those found in typical tissue culture systems, this includes the generation of cylindrical vortices around the axis of acoustic propagation [66]. Ultrasound-driven fluid streaming has been used to enhance fluid mixing in a variety of applications, including in vitro biological culture systems [67,68].…”