We have grown nanostructured films of Zn/Al Layered Double Hydroxide (LDH) on different substrates by combining the deposition of an aluminum micropatterned thin layer with a successive one-step room-temperature wet-chemistry process. The resulting LDH film is made of lamellar-like nanoplatelets mainly oriented perpendicular to the substrate. Since the aluminum layer acts as both reactant and seed for the synthesis of the LDH, the growth can be easily confined with submicrometric-level resolution (about ±0.5 μm) by prepatterning the aluminum layer with conventional photolithographic techniques. Moreover, we demonstrate real-time monitoring of the LDH growth process by simply measuring the resistance of the residual aluminum film. If the aluminum layer is thinner than 250 nm, the morphology of LDH nanoplatelets is less regular and their final thickness linearly depends on the initial amount of aluminum. This peculiarity allows accurately controlling the LDH nanoplatelet thickness (with uncertainty of about ±10%) by varying the thickness of the predeposited aluminum film. Since the proposed growth procedure is fully compatible with MEMS/CMOS technology, our results may be useful for the fabrication of micro-/nanodevices.

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Taking inspiration from our recent work in which a new sensor for hydrogen peroxide was proposed, our research group has now developed a simple, fast, and inexpensive voltametric system for determining proline concentration both in standard solutions and in real samples (red and white wines). This system uses a non-enzymatic sensor based on a working electrode of glassy carbon (GC) modified with a layered double hydroxide (LDH) compound, of the type GC-Ag(paste)-LDH-H2O2, with hydrogen peroxide in solution at fixed concentration, in a three electrode cyclic voltammetry setup. Using an increasing concentration of standard solutions of L-proline, the method shows a linearity range, in semilogarithmic coordinates, between 125 μmol L−1 and 3200 μmol L−1 of proline, with a limit of detection (LOD) value of 85.0 μmol L−1 and a limit of quantitation (LOQ) value of 95.0 μmol L−1. The developed method is applied to the determination of proline in several samples of commercial Italian wines. The results are compared with those obtained by applying the classic spectrophotometric method of ninhydrin, obtaining a good correlation of the results.