A porous SERS microneedle for multiplex detection of glucose, uric acid, and cholesterol in interstitial fluid

To detect glucose, uric acid and cholesterol in interstitial fluid simultaneously for prognosis of metabolic syndrome (MetS), a porous surface-enhanced Raman scattering (SERS) microneedle was fabricated by integrating SERS probes and three kinds of enzyme in three independent areas of one porous microneedle, respectively. Paraffin wax was used as a hydrophobic barrier to segment a porous microneedle to three independent areas, in which gold nanoshells (used as SERS substrates), 4-mercaptophenylboronic acid (4-MPBA), and one of glucose oxidase, urate oxidase, and cholesterol oxidase were integrated, respectively, and thus SERS probes altered SERS signals under the action of enzymes on their substrates. In vitro experiments demonstrated stable and accurate detection within the ranges of 0-15 mM glucose, 0-0.9 mM uric acid, and 0-9 mM cholesterol. Animal studies confirmed its feasibility for in vivo use. This porous SERS microneedle offers a minimally invasive and convenient solution for multiplex detection and point-of-care diagnosis in patients.