History and recent advances in elemental analysis of germanium-based functional materials.

This article is devoted to a review of studies on the determination of trace elements in germanium and germanium dioxide. For this purpose, methods both with and without preliminary matrix separation procedure have been developed and applied. The advantage of methods without a matrix separation procedure is simple and fast sample preparation, since it does not require specific devices or installations. On the other hand, the limits of detection (LODs) of trace elements remain relatively high, and the germanium matrix effect occurs when attempts are made to lower them. Since germanium and germanium dioxide are currently among the purest substances, the purest germanium containing trace elements at the level of pg g-1 are used for producing nuclear radiation detectors. Therefore, to achieve low LODs for trace elements, a matrix separation procedure is conducted. Another positive point is that preliminary germanium separation leads to a decrease in the matrix effect. In the article the matrix separation procedure performed by various methods is considered. These procedures can be classified into open, closed or flow kinds, depending on the type of installation. Germanium is usually separated in the form of tetrahalide, most commonly, tetrachloride. For the determination of trace elements in germanium and germanium dioxide, single element methods (atomic absorption spectrometry) and multielement methods (atomic emission spectrometry, mass-spectrometry, neutron activation analysis) are used. In this article, these methods are compared in terms of the number of elements determined and the LODs.

Biological Studies of New Implant Materials Based on Carbon and Polymer Carriers with Film Heterostructures Containing Noble Metals.

This paper presents pioneering results on the evaluation of noble metal film hetero-structures to improve some functional characteristics of carbon-based implant materials: carbon-composite material (CCM) and carbon-fiber-reinforced polyetheretherketone (CFR-PEEK). Metal-organic chemical vapor deposition (MOCVD) was successfully applied to the deposition of Ir, Pt, and PtIr films on these carriers. A noble metal layer as thin as 1 µm provided clear X-ray imaging of 1−2.5 mm thick CFR-PEEK samples. The coated and pristine CCM and CFR-PEEK samples were further surface-modified with Au and Ag nanoparticles (NPs) through MOCVD and physical vapor deposition (PVD) processes, respectively. The composition and microstructural features, the NPs sizes, and surface concentrations were determined. In vitro biological studies included tests for cytotoxicity and antibacterial properties. A series of samples were selected for subcutaneous implantation in rats (up to 3 months) and histological studies. The bimetallic PtIr-based heterostructures showed no cytotoxicity in vitro, but were less biocompatible due to a dense two-layered fibrous capsule. AuNP heterostructures on CFR-PEEK promoted cell proliferation in vitro and exhibited a strong inhibition of bacterial growth (p < 0.05) and high in vitro biocompatibility, especially Au/Ir structures. AgNP heterostructures showed a more pronounced antibacterial effect, while their in vivo biocompatibility was better than that of the pristine CFR-PEEK, but worse than that of AuNP heterostructures.