Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh Look into the Role of Particle/Substrate Interaction.

We studied the dependence of solid deposit shape obtained by free drying of sessile drops on particle concentration and Derjaguin-Landau-Verwey-Overbeek (DLVO) particle/substrate interaction. In contrast to previous contributions using pH as a control parameter of interactions, we investigated an unprecedentedly wide range of concentrations and particle/substrate DLVO forces by modifying the nature of the substrate and particles as well as their size and surface chemistry, whereas long-distance repulsive interactions between particles were maintained for most of the drying time. Our main result is that the different shapes of deposits obtained by modifying the particle concentration are the same in the different regimes of concentration regardless of particle/substrate interaction in the studied range of DLVO forces and particle concentrations. The second result is that, contrary to expectations, the dominant morphology of dry patterns at low particle concentration always shows a dotlike pattern for all the studied systems.

Morphological Control of Linear Particle Deposits from the Drying of Inkjet-Printed Rivulets.

We studied the morphology of linear particle deposits obtained by inkjet printing of a silica nanoparticle suspension in drying conditions where contact line depinning occurs. We show that this evaporation mode can be obtained by adjusting the particle concentration in different solvents. For isolated drops, deposited manually or by inkjet printing, drying induces the formation of two concentric rings in which particles self-assemble into a monolayer. For fused drops, our main result is that stable rivulets could be formed by drop overlap leading, after drying, to the formation of three parallel lines composed of a self-assembled particle monolayer. The three lines are of homogeneous thickness with two very thin outer lines (∼1 µm width) and a wider central line (∼20 µm width). We reveal how the width of the resulting lines is influenced by drop spacing in a predictable manner for a large experimental window knowing the drop size.

Peptide-modified electrolyte-gated organic field effect transistor. Application to Cu2+ detection.

This work proposes an approach for Cu2+ sensing in water which combines the selectivity of the Gly-Gly-His (GGH) peptide probe with the sensitivity of the electrolyte-gated organic field-effect transistor (EGOFET). The oligopeptide probe was immobilized onto the gate electrode of the transistor by electrooxidation of the primary amine of the glycine moiety. Cu2+ complexation by the grafted GGH was at first electrochemically evidenced, using cyclic and square wave voltammetries, then it was demonstrated that GGH-functionalized EGOFETs can transduce Cu2+ complexation through a significant threshold voltage shift and therefore a change in drain current. The limit of detection is ca. 10-12 M and the sensitivity in the linear range (10-12 - 10-8 M) is 1 mA dec-1 (drain current variations).

Triggering the Electrolyte-Gated Organic Field-Effect Transistor output characteristics through gate functionalization using diazonium chemistry: Application to biodetection of 2,4-dichlorophenoxyacetic acid.

We investigated an Electrolyte-Gated Organic Field-Effect transistor based on poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2-b]thiophene) as organic semiconductor whose gate electrode was functionalized by electrografting a functional diazonium salt capable to bind an antibody specific to 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide well-known to be a soil and water pollutant. Molecular docking computations were performed to design the functional diazonium salt to rationalize the antibody capture on the gate surface. Sensing of 2,4-D was performed through a displacement immunoassay. The limit of detection was estimated at around 2.5 fM.

Enzyme-less electrochemical displacement heterogeneous immunosensor for diclofenac detection.

We describe an electrochemical immunosensor based on functionalization of a working electrode by electrografting two functional diazonium salts. The first one is a molecular probe, diclofenac, coupled with an arylamine onto which a specific antibody is immobilized by affinity interactions; the second is a redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The steric hindrance induced by the antibody leads to a current decrease upon binding of the antibody on the grafted molecular probe; conversely, when diclofenac is present in solution, a displacement equilibrium occurs between the target diffusing into the solution and the grafted probe. This leads to dissociation of the antibody from the electrode surface, event which is transduced into a current increase ("signal-on" detection). The detection limit is ca. 20 fM, corresponding to 6pgL-1 diclofenac, which is competitive compared to other label-free immunosensors. We demonstrate that the sensor is selective and is able to quantify diclofenac in tap water.

Osteoid osteoma in the medial malleolus.

A case of osteoid osteoma in an unusual location is reported. The osteoma was diagnosed, and the nidus was localized to the anterior colliculus of the medial malleolus based on the clinical symptoms and on the findings in radionuclide bone scanning, tomography, and computerized tomographic (CT) scanning. After precise radiographic localization of the nidus, it was determined that the lesion could be excised surgically without compromising the ankle joint. The tumor was removed by en block excision and curettage. At 10 months follow-up, the patient was free of pain without impairment of function.

Retrospective analysis of intermetatarsal neuroma excision with preservation of the transverse metatarsal ligament.

The authors present a retrospective analysis of intermetatarsal neuroma excision with preservation of the transverse metatarsal ligament. They reviewed a series of 43 patients who had undergone a total of 59 such surgical resections. No other surgical procedures were performed on the foot. The patients included 36 women, and 7 men. Follow-up ranged from 1 year and 5 months to 6 years and 3 months with an average of 4 years and 3 months. Fifty-one of the neuromas removed were in the third interspace, three in the second interspace, and five in the fourth interspace. The surgical excision was performed in standard fashion except for the major modification of preservation of the transverse metatarsal ligament. There were 47 excellent or good results and, thus, the overall success rate was 79%. Seven patients had fair results and five had poor results. The results compare favorably with those reported by other authors who advocate transecting the transverse metatarsal ligament. The authors conclude that their approach to surgical excision of intermetatarsal neuromas is valid while preservation of the normal ligamentous anatomy is maintained.