A Localized Surface Plasmon Resonance-Based Portable Instrument for Quick On-Site Biomolecular Detection

In recent years, several approaches have been developed to carry out biosensors based on localized surface plasmon resonance (LSPR). However, the high costs of nanostructure fabrication and the absence of autonomous portable devices strongly limit the extensive use of LSPR biosensors outside the research laboratories. We designed, implemented, and tested a novel low cost multiparametric stand-alone LSPR imaging instrument for biosensing applications. This compact device (15 × 6 × 17 cm
³
size and <;500-g weight) consists of a nanohole array biochip integrated with a microfluidic layer and a processing system. An optical apparatus focuses a light beam from an IR LED source and a digital image sensor captures the reflected light from the biochip surface. The signals are processed by the embedded ARM processor and shown on a touchscreen display by a user-friendly application, without the need for other external computational devices. Moreover, we propose an extremely simple analytical method to reduce the image noise without any sophisticated temperature control or external luminosity change compensation. The device sensitivity of $6 \times 10^{\mathrm {-5}}$ refractive index unit was measured using glycerol solutions with different concentrations. We demonstrated the efficiency of our system in biomolecular detection by monitoring the Ab-PTX3 antibody in a test that showed the instrument's potentialities in the detection of antibodies. These results confirmed the potential usefulness of the proposed system in several biomedical applications such as medical diagnostic procedures, immunoassays, or fast in loco preliminary analyses without the aid of specialized laboratory or trained personnel.