Monodispersed poly(N-isopropylacrylamide) submicrometric microgels modified with a phenylboronic acid (PBA) derivative have been synthesized by precipitation polymerization. Particles with a well-controlled size and adjustable composition were obtained. These particles were found to be glucose responsive at a pH close to the pKa of the PBA derivative, with a swelling degree proportional to the concentration of glucose. In addition, the response to glucose was found to strongly depend on the initial state of the microgel, which depended itself on the initial temperature and the functionalization degree of the particle. This result explained the fundamental difference in the behavior of PBA-poor particles and rich ones in the presence of electrolyte. Interestingly, the latter exhibited a high swelling ratio in the presence of glucose at physiological electrolyte concentration. These particles may serve as building blocks for the design of colorimetric sensors based on the light diffraction of colloidal crystals.

The electrochemistry, photoluminescence and electrogenerated chemiluminescence of thermoresponsive redox microgels were investigated. For the first time, reversible ECL enhancement is demonstrated in stimuli-responsive 100-nm microgel particles. Such an unexpected amplification reached 2 orders of magnitude, and it is intrinsically correlated with the collapse of the microgel particles. The swell-collapse transition decreases the average distance between adjacent redox sites and favors the electron-transfer processes in the microgels resulting in the enhanced ECL emission.

We report on the synthesis of various glucose-responsive microgels based on N-alkylacrylamide derivatives and phenylboronic acid (PBA) as a glucose sensing moiety. Depending on their chemical composition, the microgels exhibit opposite behaviors in response to glucose concentration increase: they can either swell or shrink, using two different mechanisms for glucose recognition. Both behaviors may be suitable for glucose sensing and insulin delivery. When glucose binds a single boronate receptor, the microgel swells as glucose concentration increases. This mechanism can be used to deliver a drug by diffusion through the network. In other cases, glucose binds specifically to two boronates, which creates additional cross-links within the network and provokes shrinkage. Such systems are promising for the development of sensors with improved selectivity and also as potential "intelligent" valves in microfabricated delivery systems. By a rational choice of the constituting units of the network structure, we show how to favor one or the other type of response to glucose variation. Therefore, glucose-swelling microgels operating under physiological conditions have been obtained by copolymerization with an appropriate choice of alkylacrylamide monomer and boronate derivative. At a pH above the pK(a) of the boronic acid derivative, the same structures shrink in response to glucose concentration. The nature of the cross-linker is a key parameter to enable this dual behavior. In other microgels, an amine group is introduced in the vicinity of the boronic acid, which lowers its pK(a) and favors microgel contraction at physiological pH. This work has allowed us to give some general rules to control the swelling/shrinking behavior of glucose-responsive microgels.

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An efficacious strategy to obtain photostable hyper‐bright near‐IR emitting fluorescent organic nanoparticles (HIFONs) is reported. These HIFONs show excellent chemical and colloidal stability and retain their pristine nanostructure and brightness after incubation in cellular environments. They can be identified at the single particle level with a wide‐field microscope, emerging as highly promising tools for applications in bio‐nanotechnologies.

A photochromic dithienylethene, bearing a phenyl azacrown as an ionophore and a formyl group as an electron-accepting substituent, changes its binding ability for Ca2+ by a factor higher than 103 by photoirradiation. This new photoionochromic displays a wavelength-dependent competition between fluorescence and photocyclization assigned to a red-shifted absorption of the fluorescing conformer compared to the absorption of the photoreactive conformer.

A new guanidinium 3,3'-functionalized bipyridylruthenium(II) complex has been prepared for the differential sensing of L-glutamate and dihydrogenphosphate anions depending on the luminescent detection scheme. The effects of such anions on the photoluminescent (PL) and electrochemiluminescent (ECL) properties of the complex have been investigated and compared. The PL intensity increases up to fourfold in the presence of L-glutamate. The increase of intensity in the presence of dihydrogenphosphate is weaker and no change in PL intensity is observed in presence of acetate, iodide, or chloride anions. With n-tripropylamine, ECL emission of the Ru(II) complex is initiated at 1.45 V versus Ag/AgCl/KCl and the ECL intensity increases only in the presence of dihydrogenphosphate. Indeed, L-glutamate is already oxidized at the relatively high potential required for ECL generation and thus it does not affect the ECL signal. The comparison of the competitive ECL and PL assays in a mixture of anions confirms the differential detection of L-glutamate and of dihydrogenphosphate. Thus, both sensing channels (i.e., PL and ECL) show different selectivities depending on the nature and on the electroactivity of the target anions. Multianion analysis is demonstrated in competitive assays using complementary detection methods.

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