Rapid sampling of molecules via skin for diagnostic and forensic applications.
OBJECTIVE
Skin provides an excellent portal for diagnostic monitoring of a variety of entities; however, there is a dearth of reliable methods for patient-friendly sampling of skin constituents. This study describes the use of low-frequency ultrasound as a one-step methodology for rapid sampling of molecules from the skin.


METHODS
Sampling was performed using a brief exposure of 20 kHz ultrasound to skin in the presence of a sampling fluid. In vitro sampling from porcine skin was performed to assess the effectiveness of the method and its ability to sample drugs and endogenous epidermal biomolecules from the skin. Dermal presence of an antifungal drug-fluconazole and an abused substance, cocaine-was assessed in rats.


RESULTS
Ultrasonic sampling captured the native profile of various naturally occurring moisturizing factors in skin. A high sampling efficiency (79 +/- 13%) of topically delivered drug was achieved. Ultrasound consistently sampled greater amounts of drug from the skin compared to tape stripping. Ultrasonic sampling also detected sustained presence of cocaine in rat skin for up to 7 days as compared to its rapid disappearance from the urine.


CONCLUSIONS
Ultrasonic sampling provides significant advantages including enhanced sampling from deeper layers of skin and high temporal sampling sensitivity.
Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
Sumit
S
Paliwal
Makoto
M
Ogura
Samir
S
Mitragotri
D000818:Animals; D002478:Cells, Cultured; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003042:Cocaine / Q000494:pharmacology; D005233:Fatty Alcohols / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D005554:Forensic Medicine / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects; D013552:Swine; D013997:Time Factors; D014465:Ultrasonics
D005233:Fatty Alcohols; C529236:docosanol; D003042:Cocaine