Chimie bioinorganique

La chimie bioinorganique (ou biochimie inorganique ou biochimie minérale) est une spécialité scientifique à l'interface chimie-biologie, se situant plus précisément entre la biochimie et la chimie minérale (chimie des éléments métalliques). Elle s'intéresse aux espèces chimiques contenant des atomes métalliques dans les systèmes biologiques. La chimie bioinorganique s'intéresse également à la synthèse de complexes artificiels pour comprendre le fonctionnement des systèmes biologiques, voire pour en reproduire l'activité (on parle dans ce cas de chimie biomimétique). thumb|Un site actif d'une métalloprotéine : la Mn-SOD mitochondriale humaine montrant la complexation des acides aminés au manganèse. Exemples historiques Paul Ehrlich a utilisé des composés de l'arsenic pour le traitement de la syphilis, démontrant la pertinence d'utiliser des éléments métalliques (en l'occurrence, l'arsenic est un métalloïde) en médecine. Cette stratégie porta ses fruits avec la découverte

Inflight Microwave Drying Process of Micro-droplets for High Resolution 3D printing

Kwanghoon Choi

A new Additive-Manufacturing (AM) or 3D printing concept is proposed to improve the printing resolution for metal additive manufacturing in the frame of the SFA-AM project, Powder Focusing for Beam-Induced Laser 3D Printing. The project aims to transport small powder particles (largest diameter < 10 um) at a high throughput to a spot smaller than 20 µm. To realize the objective, a metal ion included liquid is suggested as a source medium similar to the inkjet process, and the droplet is employed as a container for the metal ion transport. The key challenges of achieving this goal are 1) droplet size control and 2) efficient microwave heating that can dry the liquid portion of the dynamic droplet at a high-speed (3 m/s). The most demanding part is the development of a miniaturized, very concentrated field density microwave resonator where the droplet is passing through. This follows from the extremely short interaction time between the microwave and the ejected droplets (research: 0.5 ms) which results from the requirement for a small system size for its integration. The primary medium examined for the experiment is water due to 1) a high dielectric loss proportional to the drying efficiency and 2) avoiding explosion risks at the laser sintering stage compared to organic solutions. Various droplet generation conditions were investigated to determine the optimum conditions for the custom droplet generator, in particular, two key parameters were focused on: frequency and flow rate. The droplets obtained were analyzed with respect to size, gap distance, and linearity affecting the uniformity of the AM process. Moreover, Navier-Stokes-based fluid dynamics simulations enabled understanding of droplets behaviors, especially break-up formation. Eventually, the optimal condition for producing the smallest droplets with a diameter of 100 µm is determined to be 15 kHz and 0.5 ml/min. Such droplets loaded with metallic particles could result in smaller than 20 um of remaining metal powders aggregate after the drying process.A new TEM (Transverse ElectroMagnetic) resonator has been developed for drying and sensing applications. A full-wave electromagnetic simulation software, CST Microwave Studio, supported the working mode of the device. Firstly, it is used for the dielectric characterizations of different water-ethanol mixtures contained in a micro capillary. The sensing relies on electric field perturbation due to the inserted sample, and is measured based on the change of both resonance frequency and Q-factor. These sample-dependent variations were analyzed to estimate the complex permittivity using different methods such as the Perturbation Method (PM), Least-Square Model (LSM), and Log-Linear Model (LLM). This work demonstrates that the proposed microwave module is capable of sensing nano-liter volume ranges even though the samples only partially influence the sensing area (error < 13 % in permittivity). In microwave heating, the developed resonator achieved a temperature increase of 28 K in the microwave exposal time of 0.5 ms when the microwave power of 45 W was applied. Finally, numerical models have been proposed to estimate the maximum temperature of the initial droplet before cooling starts attributable to heat and mass transfer. This model well corresponds to the microwave electromagnetic simulation resulting in similar temperature deviations. It helps to determine the net heating efficiency of the microwave device.

EPFL2022

Next-Generation Anticancer Metallodrugs

Angela Casini

More than 99% of currently approved clinical drugs are organic compounds. In contrast, the percentage of metal-containing drugs (metallodrugs) is very low. In cancer chemotherapy, however, platinum coordination compounds represented by cisplatin and derivatives thereof are essential anticancer agents with proven effects against a variety of tumors. Because of the proven clinical applications of these platinum-based drugs, the number of research initiatives to identify other metallodrugs that can be used for cancer therapy has increased considerably in the field of inorganic biochemistry. Anticancer platinum compounds continue to be designed and synthesized through several different approaches in order to improve the therapeutic effects and to overcome the disadvantages of current platinum-based drugs. The use of transition metal compounds other than platinum has also attracted attention. Gold coordination complexes, for instance, demonstrate outstanding cytotoxic properties, and certain ruthenium complexes possess a strong ability to inhibit metastases of solid invasive tumors. In this review, the potential of anticancer metallodrugs is described and representative examples from the most recent families of Pt-, Ru-, and Au-based compounds are discussed with respect to their possible modes of action and most probable biomolecular targets.

2010

Inflight Microwave Drying Process of Micro-droplets for High Resolution 3D printing

Kwanghoon Choi

EPFL2022

Inflight Microwave Drying Process of Micro-droplets for High Resolution 3D printing

Next-Generation Anticancer Metallodrugs

Inorganic chemistry 2003

Inorganic chemistry 2003

Inflight Microwave Drying Process of Micro-droplets for High Resolution 3D printing

Next-Generation Anticancer Metallodrugs