High refractive index dielectric nanoresonators are attracting much attention due to their ability to control both electric and magnetic components of light. Combining confined modes with reduced absorption losses, they have recently been proposed as an alternative to nanoplasmonic biosensors. In this context, we study the use of semi-random silicon nanocylinder arrays, fabricated with simple and scalable colloidal lithography for the efficient and reliable detection of biomolecules in biological samples. Interestingly, electric and magnetic dipole resonances are associated to two different transduction mechanisms: extinction decrease and resonance redshift, respectively. By contrasting both observables, we identify clear advantages in tracking changes in the extinction magnitude. Our data demonstrate that, despite its simplicity, the proposed platform is able to detect prostate specific antigen (PSA) in human serum with limits of detection meeting clinical needs.

Organ-on-a-chip (OOC) devices offer new approaches for metabolic disease modeling and drug discovery by providing biologically relevant models of tissues and organs in vitro with a high degree of control over experimental variables for high-content screening applications. Yet, to fully exploit the potential of these platforms, there is a need to interface them with integrated non-labeled sensing modules, capable of monitoring, in situ, their biochemical response to external stimuli, such as stress or drugs. In order to meet this need, we aim here to develop an integrated technology based on coupling a localized surface plasmon resonance (LSPR) sensing module to an OOC device to monitor the insulin in situ secretion in pancreatic islets, a key physiological event that is usually perturbed in metabolic diseases such as type 2 diabetes (T2D). As a proof of concept, we developed a biomimetic islet-on-a-chip (IOC) device composed of mouse pancreatic islets hosted in a cellulose-based scaffold as a novel approach. The IOC was interfaced with a state-of-the-art on-chip LSPR sensing platform to monitor the in situ insulin secretion. The developed platform offers a powerful tool to enable the in situ response study of microtissues to external stimuli for applications such as a drug-screening platform for human models, bypassing animal testing.

In this letter, we demonstrate a refractive index sensor based on a subwavelength plasmon interferometer. Illumination of an atilt subwavelength slit-grove pair on a metal surface with monochromatic light generates high-contrast interference fringes of the transmitted light. Detection of the refractive index of the dielectric medium on the metal surface is based on examining the relative position of the interference fringes. Integration of the plasmon interferometer with a microfluidic channel provides a sensitive, high-throughput sensor with small detection volume.