We describe the quantitative synthesis of new pyrene labeled cyclodextrin-based polyrotaxane starting from pseudopolyrotaxane of alpha,omega-dimethacrylate poly(ethylene oxide) (PEO) and alpha-cyclodextrins (alpha-CDs). Using a solvent mixture (H2O/dimethyl sulfoxide (DMSO)), an almost quantitative conversion in polyrotaxane can be achieved using the coupling reaction between methacrylic functions and 1-pyrene butyric acid N-hydroxysuccinimide ester. This result is due to the fast blocking reaction of the pseudopolyrotaxane telechelic functions. The polyrotaxanes are characterized by NMR, size exclusion chromatography (SEC), and small-angle neutron scattering (SANS). A rodlike structure of the polyrotaxane is evidenced by SANS, and a persistence length of 70 A is determined. This result corresponds to an almost completely stretched PEO chain of 1000 g.mol(-1) molecular weight. We furthermore studied the opposite case of low packing density polyrotaxanes that were also silylated to suppress interactions between cyclodextrins. We observed a random coil structure only for silylated low packed polyrotaxane. This result demonstrates that both hydrogen bonding and packing density can explain the rodlike structure of cyclodextrin-based polyrotaxane.

Electrical detection based on single nanopores is an efficient tool to detect biomolecules, particles and study their morphology. Nevertheless the surface of the solid-state membrane supporting the nanopore should be better controlled. Moreover, nanopore should be integrated within microfluidic architecture to facilitate control fluid exchanges. We built a reusable microfluidic system integrating a decorated membran, rendering the drain and refill of analytes and buffers easier. This process enhances strongly ionic conductance of the nanopore and its lifetime. We highlight the reliability of this device by detecting gold nanorods and spherical proteins.

Research on batteries mostly focuses on electrodes and electrolytes while few activities regard separator membranes. However, they could be used as a toolbox for injecting chemical functionalities to capture unwanted species and enhance battery lifetime. Here, we report the use of biological membranes hosting a nanopore sensor for electrical single molecule detection and use aqueous sodium polysulfides encountered in sulfur-based batteries for proof of concept. By investigating the host-guest interaction between polysulfides of different chain-lengths and cyclodextrins, via combined chemical approaches and molecular docking simulations, and using a selective nanopore sensor inserted into a lipid membrane, we demonstrate that supramolecular polysulfide/cyclodextrin complexes only differing by one sulfur can be discriminated at the single molecule level. Our findings offer innovative perspectives to use nanopores as electrolyte sensors and chemically design membranes capable of selective speciation of parasitic molecules for battery applications and therefore pave the way towards smarter electrochemical storage systems.

Most of the recent developments aiming to the coupling between surface plasmon resonance (SPR) and mass spectrometry (MS) are based on the use of a biochip with a limited number of flow cells requiring elution steps for the recovery of the captured biomolecules. In this work, a direct on-chip MALDI-MS detection is presented using a SPRi-sensor biochip in a microarray format that allows a multiplex SPR-MS analysis. The biochip gold surface was functionalized by a self-assembled monolayer (SAM) of short polyoxyethylene (POE) chains carrying a N-hydroxysuccinimide (NHS) group for the immobilization of biomolecules. The SPR measurement of the interaction of grafted antibodies anti-beta-lactoglobulin and anti-ovalbumin with their corresponding antigens indicated that the POE-NHS SAM preserved the binding activity of the antibodies immobilized on the biochips surface. SPR-MS experiments were carried out through MALDI-MS detection of the retained antigens (beta-lactoglobulin and ovalbumin) directly from the biochip surface. Mass spectra were obtained from each distinct spot on the arrayed biochips. Femtomole amounts of specifically retained antigen proteins as determined by SPR were sufficient to obtain good quality mass spectra. These mass spectra showed protein ions corresponding to the specific antigen, without any trace of nonspecific binding. The underivatized portion of the chip was also devoid of nonspecifically bound proteins, indicating that the functionalization of the biochips surface by short polyoxyethylene chains greatly minimizes the unspecific binding. In addition, it allowed on-chip digestion of the specifically bound analyte and coupling with MS/MS experiments, opening numerous applications in the proteomic field.

High molecular weight polyrotaxanes are usually characterized by nuclear magnetic resonance and size exclusion chromatography but rarely by mass spectrometry. This article reports effort to detect high molecular weight structures of cyclodextrin based polyrotaxanes (CD based PRs) by matrix-assisted laser desorption ionization mass spectrometry (MALDI−TOF MS). A particular attention was paid to verify the composition of the polyrotaxanes by determination of the number of macrocycles borne by the polyrotaxane and the polyrotaxanes synthetic route. Various matrices including crystalline or ionic liquid ones were screened to optimize the detection. Dimethylformamide as solvent widely used in supramolecular chemistry, but unusual in mass spectrometry, was successfully employed during all analyses. To prove the ability of the optimized MALDI−TOF MS conditions, three different polyrotaxane structures varying by polymer nature, i.e., poly(ethylene oxide) or polydimethylsiloxane and cyclodextrins type i.e. α or γ with or without modifications were evaluated. Finally, we have concluded that 1,1,3,3-tetramethylguanidinium salts of both 2-(4-hydroxyphenylazo)benzoic acid and 2′,4′,6′-trihydroxyacetophenone, are the most reliable and efficient matrices. These ones afforded the possibility to detect masses of 24804 and 26447 g·mol−1, corresponding to poly[17]- and poly[18]rotaxanes, respectively.

Biomimetic membrane channels offer a great potential for fundamental studies and applications. Here, we report the fabrication and characterization of short cyclodextrin nanotubes, their insertion into membranes, and cytotoxicity assay. Mass spectrometry and high-resolution transmission electron microscopy were used to confirm the synthesis pathway leading to the formation of short nanotubes and to describe their structural parameters in terms of length, diameter, and number of cyclodextrins. Our results show the control of the number of cyclodextrins threaded on the polyrotaxane leading to nanotube synthesis. Structural parameters obtained by electron microscopy are consistent with the distribution of the number of cyclodextrins evaluated by mass spectrometry from the initial polymer distribution. An electrophysiological study at single molecule level demonstrates the ion channel formation into lipid bilayers, and the energy penalty for the entry of ions into the confined nanotube. In the presence of nanotubes, the cell physiology is not altered.

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