Application of 3D Printing Technology to Produce Hippocampal Customized Guide Cannulas.

Implantation of guide cannulas is a widely used technique to access specific brain areas. Although commercially available, the need to personalize these implants and the high cost prompted us to design open-source customized devices taking advantage of 3D printing technology. Our cannulas consisted in a 3D-printed head mount designed according to the Paxinos coordinates to reach the CA1 area of the hippocampus. To cut guide cannulas to the proper length, we designed and realized an original 3D-printed linear motion apparatus. Polylactic acid thermoplastic polymer was used as printing material. Homemade or commercial cannulas were implanted in 4- to 6-month-old wild-type mice and intrahippocampal injections of amyloid-ß peptide at different concentrations were performed. In vivo behavioral studies of novel object recognition indicated that results obtained with homemade versus commercial devices were comparable. Methylene blue injections and Nissl staining confirmed the correct localization of cannulas in the CA1 area of mouse hippocampus. Our method allows a fast manufacturing of hippocampal cannulas preserving the required precision at very low cost. Furthermore, this system can be easily modified to produce cannulas to target other brain areas. In conclusion, 3D printing might be used as a useful and versatile technology to realize open-source customized devices in neuroscience laboratories.

Revealing Contamination and Sequence of Overlapping Fingerprints by Unsupervised Treatment of a Hyperspectral Secondary Ion Mass Spectrometry Dataset.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been successfully applied for chemical imaging of overlapping fingermarks. The resulting big dataset has been treated by means of an unsupervised machine learning approach based on uniform manifold approximation and projection. The hyperspectral matrix was composed of 49 million pixels associated with 518 peaks. However, the single-pixel spectrum results in a very poor signal intensity, mostly like a barcode. Contrary to what has been reported in the literature recently, we have not applied a crude approach based on binning but a sophisticated machine learning method capable of separating the chemical signals of the two fingerprints from each other and from the substrate in which they were impressed. Moreover, using ToF-SIMS, an extremely surface-sensitive technique, the sequence of deposition of the fingerprints has been determined.

Unsupervised Analysis of Big ToF-SIMS Data Sets: a Statistical Pattern Recognition Approach.

We present a new method, fast and low demanding in terms of CPU performances, which is able to extract latent chemical information from ToF-SIMS big data sets, such as those arising from chemical imaging, by working on the unbinned raw data files. The method is able to evaluate the similarity/dissimilarity of very low intensity spectra, such as those arising from a single pixel, in terms of symmetry and asymmetry relationships of the count distribution in the Fourier transform domain. The tests performed so far on model samples show that the method supplies results that, without sacrificing mass or spatial resolution, are equivalent, at least, to those achievable by an experienced ToF-SIMS user by applying PCA techniques.

Functionalization of oxide surfaces by terpyridine phosphonate ligands: surface reactions and anchoring geometry.

A strategy for creating a general-purposes surface functionalization platform is reported, based on direct attachment of phosphate groups onto hydroxylated surfaces and subsequent formation of a terpyridine-based monolayer. Such a platform is suitable for the construction, onto technologically relevant oxide surfaces, of single- and multilayer structures of interest in technological applications. In particular, the paper describes the successful attachment of 4-(2,2':6',2''-terpyridine-4-yl)benzenephosphonic acid (1, PPTP) onto a SiO(2) surface previously functionalized by means of Zr-phosphate groups. Two alternative anchoring strategies of the PPTP were explored: (i) a direct one-step way, implying no protection of terpyridinic functionality, and (ii) a three-step way, implying protection and successive deprotection of this group. It was found that, in the first case, the PPTP ligand anchoring to the Zr-containing phosphate layer takes place by means of terpyridinic group. At variance of this, in the second case, due to the protection of the terpyridinic functionality, the anchoring process takes place through the phosphonic group, making the terpyridinic moiety available for further reactions, i.e., multilayer constructs. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to study the functionalized surfaces, providing information on coverage, chemical structure, and stoichiometry of the various functionalized layers and, among the others, clear evidence of the PPTP linkage and orientation.

Separation and quantitation of metal ions by 4-(2-pyridylazo)resorcinol complexation in capillary electrophoresis-electrospray ionisation mass spectrometry.

The possibility of using capillary electrophoresis-electrospray ionisation (ESI)/MS to separate and quantify cobalt and iron was explored. It was necessary to tackle and overcome problems from different sources, some of them being rather unpredictable. The results obtained suggest the occurrence of oxidation processes of metal ions during the formation of the electrospray. The quantitative oxidation of cobalt(II) to cobalt(III), a process at our knowledge never described before, appears particularly interesting. The results obtained, though not optimised for sensitivity appear promising, since a limit of detection of the order of tenths of picograms was obtained. Further, from the comparison with the results obtained by optical detection, the use of CE-ESI/MS appears advantageous.

The 6-derivative of beta-cyclodextrin with succinic acid: a new chiral selector for CD-EKC.

6-O-Succinil-beta-cyclodextrin (CDsuc6) was synthesized with very good yield by one pot synthesis and characterized by NMR spectroscopy and ESI-MS. It was used as a chiral selector in capillary electrophoresis to resolve catecholamine racemates, namely norepinephrine, epinephrine, terbutaline and norphenilephrine. The CE experiments at pH 5.6 show very promising selector ability by 6-O-succinil-beta-cyclodextrin for the chiral recognition of all the catecholamines tested, while at pH 9.2, only racemic terbutaline was successfully separated.

Analytical characterization of poly(pyrrole-3-carboxylic acid) films electrosynthesised on Pt, Ti and Ti/Al/V substrates.

With the aim of developing a polymeric multilayer film for application in advanced biomaterials, as a first step poly(pyrrole-3-carboxylic acid) films (abbreviated as PPy-3-carbox) were electropolymerised from pyrrole-3-carboxylic acid solutions by cyclic voltammetry and chronoamperometry on platinum, titanium and Ti90Al6V4 substrates and characterised both electrochemically (cyclic voltammetry) and spectroscopically (X-Ray Photoelectron Spectroscopy, XPS). Electrochemical experiments showed that the potential range adopted for electropolymerization affects the polymer electroactivity, by analogy with unsubstituted polypyrrole. The combination of conventional and chemical derivation-XPS provided information on PPy-3-carbox surface structure, showing no significant difference between films grown on different substrates and an increase of the COOH groups amount (one group over three pyrrole rings, as an average) with respect to unsubstituted polypyrrole (PPy), as expected. Finally, a preliminary Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) investigation was performed in order to get further information on the polymer structure and electroactivity.