Avaliação da espessura e contaminantes de camada de óxido de diferentes implantes dentais / Evaluation of the thisckness and contaminants of the oxide layer in different implants

A proposta deste trabalho foi identificar e qualificar os elementos químicos presentes na camada de óxido de titânio bem como a espessura de cinco marcas de implantes dentais osseointegráveis. Foram submetidos à espectroscopia de fotoelétrons, excitados por raios X, implantes lisos de 3,75 x 10 mm das seguintes marcas: Nobel Biocare (Grupo A), 3I (Grupo B), Conexão (Grupo C), AS Thechnology (Grupo D) e Napio (Grupo E). As amostras relativas aos implantes dos Grupos A, B, C, D e E apresentaram espessuras médias de 15 +/- 3; 6,3 +/- 0,5; 6,0 +/- 0,2; 6,3 +/- 0,4 e 11 +/- 3 nm respectivamente. Em termos de contaminantes, os implantes do Grupo A apresentaram apenas carbono e em menor concentração que nos demais grupos. Na superfície dos implantes dos Grupos B, C, D e E, além de Carbono, também se observou a presença de comtaminantes orgânicos.

Supramolecular chemistry and technology

Supramolecular chemistry deals with the association of several chemical species, in an organized way and according to well defined purposes. Based on a molecular engineering approach, supramolecular structures can be designed from pre-formed building blocks, providing a promising route from chemistry to molecular nanotechnology. New supramolecular systems have been assembled in our laboratory with the use of bridging unities such as tetrapyridylporphyrins, porphyrazines and polypyrazines, connecting transition metal complexes and clusters. These systems display a very exciting electrochemical and catalytic behavior, and interact with DNA, generating 1O2 and leading to efficient oxidative clivage for photodynamic terapy applications. Molecular interfaces have been developed, exhibiting photocurrent response in the presence of visible-UV light, and rectifying properties in the presence of electroactive species. Successful applications of the supramolecular species in chemical and bio-sensors have been developed.

Intercalation compounds involving inorganic

Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.