Partner: A. van Wamel |
Recent publications
1. | Postema M.♦, ten Cate F.J.♦, Schmitz G.♦, de Jong N.♦, van Wamel A.♦, Generation of a droplet inside a microbubble with the aid of an ultrasound contrast agent: first result, Letters in Drug Design and Discovery, ISSN: 1570-1808, DOI: 10.2174/157018007778992847, Vol.4, pp.74-77, 2007 Abstract: New ultrasound contrast agents that incorporate a therapeutic compound have become of interest. Such an ultrasound contrast agent particle might act as the vehicle to carry a drug or gene load to a perfused region of interest. The load could be released with the assistance of ultrasound. Generally, an increase in shell thickness increases the acoustic amplitude needed to disrupt a bubble. High acoustic amplitudes, however, have been associated with unwanted effects on cells. It would be interesting to incorporate a droplet containing drugs or genes inside a microbubble carrier. A liquid core surrounded by a gas encapsulation has been referred to as antibubble. In this paper, the creation of an antibubble with the aid of ultrasound has been demonstrated with high-speed photography. Keywords:Antibubble, Ultrasound contrast agent, Drug delivery, High-speed photography Affiliations:
| |||||||||||||||||||
2. | Postema M.♦, Bouakaz A.♦, ten Cate F.J.♦, Schmitz G.♦, de Jong N.♦, van Wamel A.♦, Nitric oxide delivery by ultrasonic cracking: Some limitations, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2006.06.003, Vol.44, pp.e109-e113, 2006 Abstract: Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking. Nitric oxide, Sonic cracking Affiliations:
| |||||||||||||||||||
3. | Postema M.♦, van Wamel A.♦, ten Cate F.J.♦, de Jong N.♦, High-speed photography during ultrasound illustrates potential therapeutic applications of microbubbles, Medical Physics, ISSN: 0094-2405, DOI: 10.1118/1.2133718, Vol.32, No.12, pp.3707-3711, 2005 Abstract: Ultrasound contrast agents consist of microscopically small encapsulated bubbles that oscillate upon insonification. To enhance diagnostic ultrasound imaging techniques and to explore therapeutic applications, these medical microbubbles have been studied with the aid of high-speed photography. We filmed medical microbubbles at higher frame rates than the ultrasonic frequency transmitted. Microbubbles with thin lipid shells have been observed to act as microsyringes during one single ultrasonic cycle. This jetting phenomenon presumably causes sonoporation. Furthermore, we observed that the gas content can be forced out of albumin-encapsulated microbubbles. These free bubbles have been observed to jet, too. It is concluded that microbubbles might act as a vehicle to carry a drug in gas phase to a region of interest, where it has to be released by diagnostic ultra- sound. This opens up a whole new area of potential applications of diagnostic ultrasound related to targeted imaging and therapeutic delivery of drugs such as nitric oxide. Keywords:High-speed photography, Ultrasound contrast agent, Therapeutic microbubbles Affiliations:
| |||||||||||||||||||
4. | Postema M.♦, ten Cate F.J.♦, Lancée C.T.♦, Schmitz G.♦, de Jong N.♦, van Wamel A.♦, Ultrasonic destruction of medical microbubbles: an overview, Ultraschall in der Medizin, ISSN: 0172-4614, Vol.26, pp.S32-S33, 2005 Abstract: Purpose: Microbubble, Ultrasound Affiliations:
| |||||||||||||||||||
5. | Postema M.♦, Van Wamel A.♦, Lancee Ch.T.♦, De Jong N.♦, Ultrasound-induced encapsulated microbubble phenomena, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2004.02.010, Vol.30, No.6, pp.827-840, 2004 Abstract: When encapsulated microbubbles are subjected to high-amplitude ultrasound, the following phenomena have been reported: oscillation, translation, coalescence, fragmentation, sonic cracking and jetting. In this paper, we explain these phenomena, based on theories that were validated for relatively big, free (not encapsulated) gas bubbles. These theories are compared with high-speed optical observations of insonified contrast agent microbubbles. Furthermore, the potential clinical applications of the bubble-ultrasound interaction are explored. We conclude that most of the results obtained are consistent with free gas bubble theory. Similar to cavitation theory, the number of fragments after bubble fission is in agreement with the dominant spherical harmonic oscillation mode. Remarkable are our observations of jetting through contrast agent microbubbles. The pressure at the tip of a jet is high enough to penetrate any human cell. Hence, liquid jets may act as remote-controlled microsyringes, delivering a drug to a region-of-interest. Encapsulated microbubbles have (potential) clinical applications in both diagnostics and therapeutics. Keywords:Encapsulated microbubbles, Ultrasound contrast agent, Radiation forces, Coalescence, Fragmentation, Jets Affiliations:
| |||||||||||||||||||
6. | Postema M.♦, van Wamel A.♦, Schmitz G.♦, de Jong N.♦, Slingerende belletjes, gerichte medicijnbezorging en microïnjectienaalden, Klinische fysica, ISSN: 0168-7026, Vol.3+4, pp.6-9, 2004 Abstract: Ultrasound contrast agents consist of microscopically small encapsulated bubbles that oscillate upon insonification. To enhance diagnostic ultrasound imaging techniques and to explore therapeutic applications, these medical bubbles have been studied with the aid of high-speed photography. We filmed medical bubbles at higher frame rates than the ultrasonic frequency transmitted. Microbubbles have - among others - been observed to fragment and jet during one single ultrasonic cycle. Gas was released from encapsulated microbubbles. It is concluded that bubbles might act as a vehicle to carry a drug in gas phase to a region of interest, where it has to be released by ultrasound whose amplitudes are still in the diagnostic range. Keywords:Oscillating bubbles, Targeted drug delivery, Micro-injection needles Affiliations:
|
List of chapters in recent monographs
1. 455 | Postema M., Gilja O.H.♦, van Wamel A.♦, Fundamentals of Medical Ultrasonics, rozdział: CEUS and sonoporation, Spon Press, pp.205-217, 2011 |
Conference papers
1. | Postema M.♦, de Jong N.♦, Schmitz G.♦, van Wamel A.♦, Creating antibubbles with ultrasound, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603013, Vol.2, pp.977-980, 2005 Abstract: Ultrasound contrast agents have been investigated for their potential applications in local drug and gene delivery. A microbubble might act as the vehicle to carry a drug or gene load to a perfused region of interest. The load has to be released with the assistance of ultrasound. We investigate the suitability of antibubbles for ultrasound-assisted local delivery. As opposed to bubbles, antibubbles consist of a liquid core surrounded by a gas encapsulation. Incorporating a liquid drop containing drugs or genes inside an ultrasound contrast agent microbubble, however, is technically challenging. Antibubble, Ultrasound Affiliations:
| |||||||||||||
2. | de Jong N.♦, Bouakaz A.♦, van Wamel A.♦, Postema M.♦, Versluis M.♦, Microbubbles for ultrasound imaging and therapy, Workshop on Ultrasound in Biomeasurements, Diagnostics and Therapy, Vol.2, pp.123-126, 2004 |