Photomechanical Drug Pictures

Photoacoustic drug delivery is a technique for delivering drugs to localized areas [Shangguan 1995a, Shangguan 1995b]. Unlike the techniques for enhancing local delivery of molecules using laser-induced shock waves [Zeimer 1988, Flotte 1995], photomechanical drug delivery uses a laser pulse to generate a cavitation bubble in a blood vessel due to the absorption of laser energy by targets (e.g., blood clots) or surrounding liquids (e.g., blood). The cavitation bubble expands and collapses hundreds of microseconds after the laser pulse. The hydrodynamic pressure arising from the expansion and collapse of the cavitation bubble can force the drug into clot or vessel wall. Photomechanical drug delivery can be performed by timing the laser pulses to be coincident with an injected bolus of drug. The delivery system for photomechanical drug delivery could consist of only two elements: an optical fiber or light guide for delivering laser pulses, and catheter tubing for injecting drugs. A fluid-core laser catheter has been used to remove thrombus (blood clot) with a pulsed-dye laser without damaging the vessel wall tissue [Gregory 1990]. Photomechanical drug delivery with such a fluid-core laser catheter may be an alternative method to current techniques for localized drug delivery.

Selected pictures from HanQun Shangguan's thesis.

Close-ups for Frank Blanchard

This is a side view of bubble formation in a 300/cm oil solution confined in a 3mm silicone tube. Single pulses of 33mJ were delivered via a 300µm fiber. The picture was taken at 250µs.

250.GIF, 241K This is an untouched original of the 250 microsecond picture from the 141k montage shown below.

250a.GIF, 676K A 300dpi cropped version of the above file. This was obtained from 250.gif by croping the image and running it through graphic converter and changing the resolution to 300dpi. It does not have any more information, nor is it much clearer.

Figure (3K) Experimental setup for time-resolved flash photography of laser-induced bubble created at the fiber tip in absorbing liquids (water and oil).

Chapter 3

Figure (3K) Experimental setup for time-resolved flash photography of laser-induced bubble created at the fiber tip in absorbing liquids (water and oil).
Figure (74k) Bubble formation at the fiber tip in 100/cm water and oil.

Chapter 4

Figure (6k) Schematic of high-speed photographic system.
Figure ch4.60bcon Flash photographs in side view of bubble growth and collapse on absorbing gelatin surface after the laser pulse. Single pulses of 50mJ were delivered onto the surface of clear gelatin (3.5% 60 bloom) covered with a 300/cm oil solution via a 1000µm fiber. The fiber tip was slightly in contact with the gelatin surface.
Figure (198k) Flash photographs in side view of bubble growth and collapse on absorbing gelatin surface after the laser pulse. Single pulses of 50mJ were delivered onto absorbing gelatin surface (3.5% 300 bloom, 100/cm) through clear water via a 300µm fiber. The fiber tip was placed 1mm above the gelatin surface.
Figure (141k) Side view of bubble formation in a 300/cm oil solution confined in a 3mm silicone tube. Single pulses of 33mJ were delivered via a 300µm fiber.
Figure (136k) Side view of bubble formation in a 300/cm oil solution confined in a 3mm silicone tube. Single pulses of 100mJ were delivered via a 1000µm-fiber.
Figure (121k) Side view of bubble formation in a semi-infinite space (top panel) and in a 3mm tube (bottom panel). Single pulses of 100mJ was delivered into a 300/cm water solution via a 1000µm fiber. The maximal bubble diameter and dilation of the tube wall were observed at 300µs and 60µs respectively after the laser pulse. The invagination of the tube was 84% of the initial value about 900µs after the laser pulse.

Chapter 5

Figure (4k) Experimental setup for time-resolved PIV of the flow around a laser-induced cavitation bubble.
Figure (91k) PIV/flash photograph of a cavitation bubble near a gelatin target 10-100µs after a laser pulse. A 60mJ laser pulse was delivered via an optical fiber with a 1000µm core diameter. The maximum bubble diameter was 2.5mm at 100µs. The marked velocity was the average for this specific particle train during the bubble expansion. The white bar presents 1mm in length. The white dashed line indicates the surface of the gelatin target. Five exposures were used with the presented pulse profile.

Chapter 7

Figure (3k) Schematic of experimental setup for visualizing the bubble formation on clot or gelatin.
Figure (83k) A laser-induced cavitation bubble formed in the clot. The right photo was taken to show the spherical shape of the bubble on the left.
Figure (179k) A series of flash photographs of cavitation bubble growth and collapse after the laser pulse. Single pulses of 50mJ were delivered onto the clot via a 300µm fiber. The clot was confined in a gelatin sample with a cylindrical channel at center. The fiber was placed 1mm above the clot under water.