RSC Adv.

Current biomedical imaging techniques are vital for the diagnosis of various diseases. They are related to the development of multimodal probes encompassing all the functionalities required for comprehensive imaging. In this context, we applied a simple and reproducible wet synthesis route to produce such probes. This method allowed us to prepare about 100 nm sized lanthanide-doped yttrium fluoride nanoparticles β-NaY0.8[Yb0.18Er0.02]F4, coated with about 10 nm sized iron oxide γ-Fe2O3 nanocrystals. By this way, the built granular hetero-nanostructures combine desirable up-converting photoluminescence (the core) and superparamagnetic properties (the satellites), enabling dual optical and magnetic resonance imaging applications. Through citrate ligand grafting, the designed core–satellite particles formed stable aqueous colloids, which are valuable for biomedical applications. Optical spectroscopy and confocal microscopy revealed their capability for sustained visible light emission (predominantly green) upon near-infrared excitation (980 nm). Additionally, based on XTT assays, when incubated for 24 hours with mammalian healthy or cancer cells, even at doses as high as 0.1 mg mL−1 (milligrams of particles), they did not induce significant cytotoxicity. The measured body temperature magnetization of the engineered nanoconstructs was found to be about 10 emu g−1 (grams of particles) at 1.5 T, which is high enough to use them as positive or negative contrast magnetic resonance agents in the clinic, as confirmed by relaxometry measurements in Milli-Q water. This result underscores their promising biomedical utility as bimodal probes for optical and magnetic imaging

Sensing Polymer/Paracetamol Interaction with an Independent Component Analysis-Based SERS-MIP Nanosensor

In this article, we propose a new strategy to build a sensor for easy handling and rapid analysis on-site. Our sensor is based on the combination of surface-enhanced Raman spectroscopy (SERS) and molecularly imprinted polymers (MIPs). SERS provides a strong sensitivity for the detection of trace molecules while MIPs offer a highly selective and specific recognition platform. The research presented here focuses on the detection of the interaction between a robust ultra-thin layer of MIPs and of paracetamol, the targeted molecule. This drug is an environmental emerging pollutant, i.e., a molecule whose presence and significance have not yet been elucidated, which gives rise to health and environmental concerns. The results are a combined analysis of the SERS spectra and a multivariate analysis. The former provides a clear demonstration of the evolution of the MIP-nanostructure interaction when the concentration of paracetamol increases. The statistical analysis produces the proof of the selectivity of the senso

Multi-functionalization of lithographically designed gold nanodisks by plasmon-mediated reduction of aryl diazonium salts

International audiencePlasmon-driven surface functionalization of nanoparticles is receiving growing attention as it allows generating locally tailored chemical reactivity on the nanoparticle surface. The extension to surface multi-functionalization still represents a major breakthrough in chemistry. We address this issue by triggering regiospecific surface double-functionalization under plasmon excitation, using diazonium salts as surface functionalization agents