Hollow Microneedle‐based Plasmonic Sensor for on Patch Detection of Molecules in Dermal Interstitial Fluid

Interstitial fluid (ISF) extraction and analysis are challenges that can be tackled by Hollow MicroNeedles (HMNs) technology, overcoming most of the difficulties associated with in situ detection. Herein, a plasmonic transducer, composed of gold nanoparticles embedded in poly(ethylene glycol) diacrylate (PEGDA) hydrogels, is integrated in the inner cavity of HMNs to detect biomarkers from the ISF-based point-of-care. The wearable HMN-based patch is used for minimally invasive pierce of the skin. The large swelling capability of the plasmonic transducer allows the uptake of ISF by capillarity. Biotin, as a small model molecule, is efficiently collected in the inner cavity of HMN and its high specificity with the streptavidin is exploited as a validation of the plasmonic nanocomposite functionality embedded within. The recognition of biotin is achieved in dual-optical mode: the localized surface plasmon resonance (label-free) and the metal-enhanced fluorescence (label-based). Overall, the proposed HMN-based patch for target sensing in ISF can represent a novel point-of-use device for the detection of biomarkers as an alternative to conventional hospital or lab settings to help faster medical decision-making.