Kinetics of germanium dioxide in rats

Laser-Synthesized Germanium Nanoparticles as Biodegradable Material for Near-Infrared Photoacoustic Imaging and Cancer Phototherapy

Biodegradable nanomaterials can significantly improve the safety profile of nanomedicine. Germanium nanoparticles (Ge NPs) with a safe biodegradation pathway are developed as efficient photothermal converters for biomedical applications. Ge NPs synthesized by femtosecond-laser ablation in liquids rapidly dissolve in physiological-like environment through the oxidation mechanism. The biodegradation of Ge nanoparticles is preserved in tumor cells in vitro and in normal tissues in mice with a half-life as short as 3.5 days. Biocompatibility of Ge NPs is confirmed in vivo by hematological, biochemical, and histological analyses. Strong optical absorption of Ge in the near-infrared spectral range enables photothermal treatment of engrafted tumors in vivo, following intravenous injection of Ge NPs. The photothermal therapy results in a 3.9-fold reduction of the EMT6/P adenocarcinoma tumor growth with significant prolongation of the mice survival. Excellent mass-extinction of Ge NPs (7.9 L g-1 cm-1 at 808 nm) enables photoacoustic imaging of bones and tumors, following intravenous and intratumoral administrations of the nanomaterial. As such, strongly absorbing near-infrared-light biodegradable Ge nanomaterial holds promise for advanced theranostics.

Ti-Ge binary alloy system developed as potential dental materials

As-cast Ti-xGe (x = 2, 5, 10, 20 wt %) binary alloys were produced in this work, and various experiments were carried out to investigate the microstructure, mechanical properties, in vitro electrochemical and immersion corrosion behaviors as well as cytotoxicity with as-cast pure Ti as control, aiming to study the feasibility of Ti-xGe alloy system as potential dental materials. The microstructure of Ti-xGe alloys changes from single α-Ti phase to α-Ti + Ti(5)Ge(3) precipitation phase with the increase of Ge content. Mechanical tests show that Ti-5Ge alloy has the best comprehensive mechanical properties. The corrosion behavior of Ti-xGe alloys in artificial saliva with different NaF and lactic acid addition at 37°C indicates that Ti-2Ge and Ti-5Ge alloys show better corrosion resistance to fluorine-containing solution. The cytotoxicity test indicates that Ti-xGe alloy extracts show no obvious reduction of cell viability to L-929 fibroblasts and MG-63 osteosarcoma cells, similar to pure Ti which is generally acknowledged to be biocompatible. Considering all these results, Ti-2Ge and Ti-5Ge alloys possess the optimal comprehensive performance and might be used as potential dental materials.

Functional changes on ascending auditory pathway in rats caused by germanium dioxide exposure: an electrophysiological study

The semiconductor element, germanium (Ge), is essential for the manufacture of modern integrated circuits. Because of its anti-tumor and immunomodulative effects, Ge-containing compounds are also used as health-promoting ingredients in food. However, some histological studies have shown the toxic effects of Ge-containing compounds on various organs, including the central nervous system. Even now, the effect of germanium on auditory system function is not completely clear. To clarify this question, brainstem auditory evoked potentials (BAEPs) were applied to examine the effect of germanium dioxide (GeO(2)) on the ascending auditory pathway. Since the voltage-gated sodium channel is important to neuron activation and nerve conduction, the effect of GeO(2) on voltage-gated sodium channels was also examined. The result revealed GeO(2) elevated the BAEPs threshold dose-dependently. GeO(2) also prolonged latencies and interpeak latencies (IPLs) of BAEPs, but the amplitudes of suprathreshold intensities (90dB) did not show any obvious change. In addition, the results of whole cell patch clamp studies indicated GeO(2) reduced inward sodium current. These results suggest the toxic effect of GeO(2) on the conduction of the auditory system, and that inhibitory effect of GeO(2) on the voltage-gated sodium channels might play a role in GeO(2)-induced abnormal hearing loss.

Germanium dioxide induces mitochondria-mediated apoptosis in Neuro-2A cells

Germanium (Ge) is commonly used in the semiconductor industry as well as health-promoting and medical field. Biologically, germanium possesses erythropoietic, anti-microbial, anti-tumor, anti-amyloidosis, and immunomodulative effects. However, toxic effects of Ge-containing compounds on kidney, muscle, neuronal cells, and nerves have been reported. Mitochondrial dysfunction was found to be involved in the pathogenesis of GeO(2)-induced nephropathy and myopathy. Since it is well known that mitochondria play a major role in apoptosis triggered by many stimuli, an effort was made to examine whether the Ge-induced neurotoxicity occurs through mitochondria-mediated apoptosis. A mouse neuroblastoma cell line, Neuro-2A, was used in the present study. After incubating with 0.1-800microM of GeO(2) for 0-72h, the cell viability of Neuro-2A cells was inhibited in a dose- and time-dependent manner. Further analysis showed that aside from the changes in the nuclear morphology responsible for apoptosis, the release of cytochrome c, the loss of mitochondrial membrane potential, the translocation of Bax, and the reduction of Bcl-2 expression were also observed in Neuro-2A cells after GeO(2) treatment. These results indicate that the mitochondria-mediated apoptosis is involved in this in vitro model of GeO(2)-induced neurotoxicity.

Analytical product study of germanium-containing medicine by different ICP-MS applications

For several years organo-germanium containing medicine has been used for special treatments of e.g. cancer and AIDS. The active substances contain germanium as beta-carboxyethylgermanium sesquioxide ((GeCH2CH2COOH)203/"Ge-132"), spirogermanium, germanium-lactate-citrate or unspecified forms. For humans, germanium is not essential and in general the toxicity of the mentioned organo-germanium compounds is low. Acute and chronic toxic effects of inorganic germanium dioxide have been demonstrated. It is obvious that especially inorganic germanium has a higher potential of negative effects. Therefore, a widespread analytical product control is indispensable. Inductively coupled plasma mass spectrometry (ICP-MS) is the preferred technique and different applications were developed for controlling various parameters: (i) A speciation method using high performance liquid chromatography (HPLC) coupled with quadrupole (Q-) ICP-MS was developed for the identification of organo-germanium species in medicine. (ii) The nuclear magnetic resonance (NMR) technique was applied to confirm the molecular structure and to determine the molecule concentration. (iii) The total concentration of germanium in the medicine was determined in the diluted sample by high resolution (HR-) ICP-MS. (iv) For a general overview, a multi-element screening method of 56 elements with HR-ICP-MS was developed. The semi-quantitative mode was used for quantification and elements of higher abundance are reported. (v) Investigations about matrix-based interferences on masses of isotopes, which are generally determinable without remarkable problems. Isotopes like e.g. 85Rb, 88Sr, 89y, 90Zr, 93Nb and the isotopes of Ba are strongly interfered by different Ge-based molecules and need to be analysed in a higher resolution mode than used for other common matrices.