Integration of Metal-Organic Polyhedra onto a Nanophotonic Sensor for Real-Time Detection of Nitrogenous Organic Pollutants in Water

The grave health and environmental consequences of water pollution demand new tools, including new sensing technologies, for the immediate detection of contaminants in situ. Herein, we report the integration of metal-organic cages or polyhedra (MOCs/MOPs) within a nanophotonic sensor for the rapid, direct, and real-time detection of small (<500 Da) pollutant molecules in water. The sensor, a bimodal waveguide silicon interferometer incorporating Rh(II)-based MOPs as specific chemical receptors, does not require sample pretreatment and enables minimal expenditure of time and reagents. We validated our sensor for the detection of two common pollutants: the industrial corrosion inhibitor 1,2,3-benzotriazole (BTA) and the systemic insecticide imidacloprid (IMD). The sensor offers a fast time-to-result response (15 min), high sensitivity, and high accuracy. The limit of detection (LOD) in tap water for BTA is 0.068 μg/mL and for IMD, 0.107 μg/mL, both of which are below the corresponding toxicity thresholds defined by the European Chemicals Agency (ECHA). By combining innovative chemical molecular receptors such as MOPs with state-of-the-art photonic sensing technologies, our research opens the path to implement competitive sensor devices for in situ environmental monitoring.

High Throughput Nanoimaging of Thermal Conductivity and Interfacial Thermal Conductance

Thermal properties of materials are often determined by measuring thermalization processes; however, such measurements at the nanoscale are challenging because they require high sensitivity concurrently with high temporal and spatial resolutions. Here, we develop an optomechanical cantilever probe and customize an atomic force microscope with low detection noise ≈1 fm/Hz^1/2 over a wide (>100 MHz) bandwidth that measures thermalization dynamics with ≈10 ns temporal resolution, ≈35 nm spatial resolution, and high sensitivity. This setup enables fast nanoimaging of thermal conductivity (η) and interfacial thermal conductance (G) with measurement throughputs ≈6000× faster than conventional macroscale-resolution time-domain thermoreflectance acquiring the full sample thermalization. As a proof-of-principle demonstration, 100 × 100 pixel maps of η and G of a polymer particle are obtained in 200 s with a small relative uncertainty (<10%). This work paves the way to study fast thermal dynamics in materials and devices at the nanoscale.

Real Time Monitoring of a UV Light-Assisted Biofunctionalization Protocol Using a Nanophotonic Biosensor

A protocol for the covalent biofunctionalization of silicon-based biosensors using a UV light-induced thiol–ene coupling (TEC) reaction has been developed. This biofunctionalization approach has been used to immobilize half antibodies (hIgG), which have been obtained by means of a tris(2-carboxyethyl)phosphine (TCEP) reduction at the hinge region, to the surface of a vinyl-activated silicon-on-insulator (SOI) nanophotonic sensing chip. The response of the sensing structures within the nanophotonic chip was monitored in real time during the biofunctionalization process, which has allowed us to confirm that the bioconjugation of the thiol-terminated bioreceptors onto the vinyl-activated sensing surface is only initiated upon UV light photocatalysis.