Label-free detection of protein binding with multisine SPR microchips

Kinetics of Reactive Modules Adds Discriminative Dimensions for Selective Cell Imaging

Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears highly desirable. One attractive road to address this analytical challenge relies on engaging the targets in reactions and exploiting the rich kinetic signature of the resulting reactive module, which originates from its topology and its rate constants. This review explores the various facets of this promising strategy. We first emphasize the singularity of the content of a living cell as a chemical mixture and suggest that its multiplexed observation is significant and timely. Then, we show that exploiting the kinetics of analytical processes is relevant to selectively detect a given analyte: upon perturbing the system, the kinetic window associated to response read-out has to be matched with that of the targeted reactive module. Eventually, we introduce the state-of-the-art of cell imaging exploiting protocols based on reaction kinetics and draw some promising perspectives.

A metal-responsive interdigitated bilayer for selective quantification of mercury(ii) traces by surface plasmon resonance

An innovative design of reusable SPR chips allowing the quantitative and selective determination of mercury(ii) at the ppt level is reported.

Development of gadolinium based nanoparticles having an affinity towards melanin

Small Rigid Platforms (SRPs) are sub-5 nanometre gadolinium based nanoparticles that have been developed for multimodal imaging and theranostic applications. They are composed of a polysiloxane network surrounded by gadolinium chelates. A covalent coupling with quinoxaline derivatives has been performed. Such derivatives have proven their affinity for melanin frequently expressed in primary melanoma cases. Three different quinoxaline derivatives have been synthesised and coupled to the nanoparticles. The affinity of the grafted nanoparticles for melanin has then been shown in vitro by surface plasmon resonance on a homemade melanin grafted gold chip.

A droplet-based novel approach for viable and low volume consumption surface plasmon resonance bio-sensing inside a polydimethylsiloxane microchip

Over the course of last two decades, surface plasmon resonance (SPR) has emerged as a viable candidate for label-free detection and characterization for a large pool of biological interactions, ranging from hybridization of oligonucleotides to high throughput drug-screening. Conventional SPR bio-sensing involves a step-response method where the SPR sensorgram in response to a switched sequential flow of analyte and buffer is plotted in real-time and fitted to an exponential curve to extract the associative and dissociative reaction rates. Such measurement schemes involve continuous flow conditions where a substantial reagent volume is consumed and is subject to dispersive mixing at flow switching zones. In this paper, we demonstrate a new plug-train SPR technique in a microfluidic chip that separates and singulates solvent plugs in analyte and buffer by an immiscible air phase. Bio-samples are first discretized within plug droplets with volumes in order of few hundred nanoliters or less followed by pressure-driven transport onto SPR sensing sites of this hydrophobically modified SPR microdevise. The kinetic constants ka and kd for a model protein-small molecule interaction pair are extracted from a plug-train signal and are shown to be in reasonable agreement with our previous reports.

Joining plasmonics with microfluidics: from convenience to inevitability

Along the advances in optofluidics, functionalities based on the surface plasmon-polariton have also been finding an increasing level of involvement within micro/nano-fluidic systems, gradually forming a new field of plasmo-fluidics. This survey of the burgeoning field reveals that judicious selection and combination of plasmonic and micro/nano-fluidic features render the plasmo-fluidic integration useful and mutually beneficial to the point of inevitability. We establish categories for the level of integration and utilize them as a framework for surveying existing work and extracting future perspectives.