Two-in-one sensor of refractive index and Raman scattering using hollow−core microstructured optical waveguides for colloid characterization

Abstract

Hollow−core microstructured optical waveguides (HC−MOW) have recently emerged in sensing technologies, including the gas and liquid detection for industrial as well as clinical applications. Antiresonant HC−MOW provide capabilities for applications in refractive index (RI) sensing, while the long optical path for analyte−light interaction in HC−MOW leads to increased sensitivity of sensor based on Raman scattering signal measurements. In this study, we developed a two−in−one sensor device using HC−MOW for RI and Raman scattering detection. The performance of the sensor was evaluated by characterizing protein−copolymer multicomponent colloids, specifically, bovine serum albumin (BSA) and poly(N − vinyl−2 −pyrrolidone−co−acrylic acid) P(VP−AA) nano−sized complexes and microbubbles of the corresponding shell. Monocomponent solutions showed linear dependencies of RI and characteristic Raman peak intensities on mass concentration. Multicomponent Raman sensing of BSA@P(VP−AA) complexes and microbubbles revealed that changes in P(VP−AA) characteristic peak intensities can describe interactions between components needed to produce colloid systems. RI sensing of multicomponent colloids demonstrated linear dependence on total mass concentrations for BSA@P(VP−AA) complexes, while corresponding BSA@P(VP−AA) microbubbles can be detected with concentrations as high as 4.0 × 108 MB/mL. Therefore, the developed two−in−one sensor of RI and Raman scattering can be used the robust characterization of albumin−based colloids designed for therapeutic and diagnostic needs.