title: Characterizing bubble dynamics created by high-intensity focused ultrasound for the delivery of antibacterial nanoparticles into a dental hard tissue.
abstract: Hig hintensity focused ultrasound (HIFU) has been applied for drug delivery in various disease conditions. Delivery of antibacterial-nanoparticles into dental hard tissues may open up new avenues in the treatment of dental infections. However, the basic mechanism of bubble dynamics, its characterization, and working parameters for effective delivery of nanoparticles, warrants further understanding. This study was conducted to highlight the basic concept of HIFU and the associated bubble dynamics for the delivery of nanoparticles. Characterization experiments to deliver micro-scale particles into simulated tubular channels, activity of ultrasonic bubbles, and pressure measurement inside the HIFU system were conducted. Subsequently, experiments were carried out to test the ability of HIFU to deliver nanoparticles into human dentine using field emission scanning electron micrographs (FESEM) and elemental dispersive X-ray analysis (EDX). The characterization experiments showed that the bubbles collapsing at the opening of tubular channels were able to propel particles along their whole length. The pressure measured showed sufficient negative and positive pressure suggesting that the bubble grew to a certain size before collapsing, thus enabling the particles to be pushed. The FESEM and EDX analysis highlighted the ability of HIFU to deliver nanoparticles deep within the dentinal tubules. This study highlighted the characteristics and the mechanism involved of the bubbles generated by the HIFU and their capability to deliver nanoparticles.
authors.affiliation: Department of Mechanical Engineering, University of California, 6141 Etcheverry Hall, Berkeley, CA 94720-1740, USA. ohlsw@berkeley.edu
authors.forename: S W
authors.initials: SW
authors.lastname: Ohl
authors.forename: A
authors.initials: A
authors.lastname: Shrestha
authors.forename: B C
authors.initials: BC
authors.lastname: Khoo
authors.forename: A
authors.initials: A
authors.lastname: Kishen
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D003804:Dentin / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods*; D006801:Humans; D045423:Microbubbles / Q000627:therapeutic use*; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry / Q000627:therapeutic use*; D013052:Spectrometry, X-Ray Emission; D014070:Tooth / Q000033:anatomy & histology; D014463:Ultrasonography / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents