Laser-induced capillary leakage for blood biomarker detection and vaccine delivery via the skin.

Laser-induced capillary leakage (a) to induce extravasation of circualing molecules only (b) or facilitate entry of attenuated malaria sporozoites into the capillary (c). Skin illumination with a laser preferably absorbed by hemoglobin causes dilation of the capillary beneath the skin. The extravasated molecules can be sufficiently measured in the skin or guide sporozoites to enter the vessel. Circulation system is the center for coordination and communication of all organs in our body. Examination of any change in its analytes or delivery of therapeutic drugs into the system consists of important medical practice in today's medicine. Two recent studies prove that brief illumination of skin with a low powered laser, at wavelengths preferentially absorbed by hemoglobin, increases the amount of circulating biomarkers in the epidermis and upper dermis by more than 1,000-fold. When probe-coated microneedle arrays are applied into laser-treated skin, plasma blood biomarkers can be reliably, accurately, and sufficiently quantified in 15∼30 min assays, with a maximal detection in one hr in a manner independent of penetration depth or a molecular mass of the biomarker. Moreover, the laser treatment permits a high efficient delivery of radiation-attenuated malarial sporozoites (RAS) into the circulation, leading to robust immunity against malaria infections, whereas similar immunization at sham-treated skin elicits poor immune responses. Thus this technology can potentially instruct designs of small, portable devices for onsite, in mobile clinics, or at home for point-of-care diagnosis and drug/vaccine delivery via the skin.