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New Materials

Self cleaning scalpel

Ceramic coating sterilizes medical and dental instruments

MIGUEL BOYAYANPrototypes of metallic materials covered with the ceramic based on titanium oxide MIGUEL BOYAYAN

The combating of hospital infections is gaining a new ally. This is a fine layer of a ceramic material based on titanium oxide that groups together bactericidal and anti-microbe properties on the surface of medical and dental instruments such as scalpels, pincers and drills. The good news for health professionals and patients comes from the company Science Solution, a spin-off of the Interdisciplinary Laboratory of Electrochemistry and Ceramics (Liec) of the Chemistry Institute of the São Paulo State University (Unesp) in the town of Araraquara. The four partner-researchers, Luiz Gustavo Pagotto Simões, André Luiz de Araújo, Daniel Tamassia Minozzi and Cauê Ribeiro, all chemistry graduates from the Federal University of Sao Carlos (UFSCar), did their Post-Graduation at Unesp and run the company installed at the Technology Companies Incubator Center (Cinet) of the Parqtec Foundation, in Sao Carlos.

The research work at the university led to the four creating a nanostructured material that is self-sterilizing and was dubbed the Nanox Bactericida. It is a type of ceramic ink that does not alter the original properties of the surgical instruments. The technology spawned  two patents and is already being negotiated with industrial companies, both national and abroad, that produce medical and dental instruments, whose names remain anonymous at the request of the companies themselves.

The utensils covered with the nanometric film of titanium dioxide (TiO2) have their bactericidal properties activated when they are in the presence of ultraviolet light (UV), present in chambers with this type of radiation or even in the presence of sunlight. As well as destroying the cellular wall of the bacteria, this system also eliminates fungi and all organic material. “The effect of the light upon the material brings an oxidation-reduction process into action, in which two materials interact, with the loss and gain of electrons. In this case the interaction with the titanium oxide, under the action of UV, degrades the organic material.” This physical-chemical process is similar to rusting that grows upon an iron bar, under the action of temperature and humidity, absorbing and reacting with oxygen.

Without dirt
“The TiO2 also decomposes coloring material, fats and agricultural preservatives” advised partner Simões. “Another of the material’s properties is that it’s self cleaning. It’s efficient in the cleaning of dirt and of small quantities of fat, and, for this reason, can also be applied to a large number of products with steel, ceramic and glass surfaces, such as stoves, refrigerators, car glass windows, and the glass windows of buildings and homes.” In Japan, the walls and floors of some hospitals are painted with paints containing micrometric particles of TiO2 in order to minimize the possibility of contamination of the environments and to reduce the index of hospital infection.

The production of the new bactericidal coating, the researcher advised, is of relatively low cost and does not require sophisticated equipment. Firstly the material that is going to receive the coating is immersed in a receptacle containing a water based liquid polymer with titanium ions at room temperature. Afterwards it is heated in an oven to between 300 and 400 Celsius degrees. The thermal treatment makes the titanium ions transform themselves into titanium dioxide. From between four to six hours the nanostructured bactericidal film is formed on the material’s surface. “In theory, the medical-dental instruments coated with Nanox do not need to be sterilized in autoclaves, as is currently the case. It would be enough to put them in a chamber in the presence of ultraviolet light, because the bactericidal film that covers them is photoactive” says  Simões.

As well as the nanostructured film, the new material can also be produced in powder form. In this case the Nanox has various applications related to its capacity for the absorption of ultraviolet rays. This is because at the same time that it possesses the bactericidal effect, the product impedes the UV radiation from penetrating into the material. “The solar filters for UV radiation protection, for example, possess in their composition titanium dioxide, but of a different chemical state from that used in the instruments. By adding small fractions of powdered Nanox it’s possible to power up the protective action of solar filters”  says Araújo. He clarified that, in the bactericidal, the titanium dioxide is in the anatase state and in the solar protector it is in the rutile state. “A state, in chemistry, is the name given to a determined form of a material in which it maintains the same chemical composition, but with a different spatial atomic arrangement” says Araújo. Titanium dioxide possesses three distinct phases (anatase, rutile and brookite) and when it is 100% in the anatase phase its bactericidal properties are powered up. According to the researchers from Science, there is a product similar to Nanox being sold in Brazil by a German multinational company, but which is not 100% in the anatase phase. As well as this, this other material is not available in the form of a nanostructured film, but only as a powder, which limits its field of application.

In order to develop the product, the four partners of Science were able to count upon Liec’s technological support, the laboratory that is part of the  Multidisciplinary Center for the Development of Ceramic Materials (CMDMC), one of the ten Research, Innovation and Diffusion Centers (CEPIDS) maintained by FAPESP. To fund the research the company had the support of FAPESP’s Technological Innovation in Small Businesses (PIPE) Program. Of the two patents already deposited at the National Institute for Industrial Property (INPI), the first refers to the generic process of obtaining the films and nanostructures oxides, and the other is related to the bactericidal effect of the films and post nanometric 100% anatase phase.

Founded in July of 2004, the Science company was born with the objective of developing coatings and nanometric oxides for modeling, the modification of surfaces and industrial applications, principally in the petrochemical industry. The expectation of the researchers is to place Nanox on the market in July of this year, during an exhibition of hospital products in São Paulo. “We’re already in negotiation with companies in the medical-hospital sectors and electro domestic sector of ovens, refrigerators, etc. Recently we participated in a nanotechnology fair and a Swiss company showed interest in our product. We covered some high precision pincers for surgical use and for the manipulation of semiconductors, which are being tested in Switzerland” advised partner Luiz Simões. “At the same time, we’ve already carried out laboratory tests with small plaques of the stainless steel of ovens and refrigerators. Now we’re going to make applications on larger parts so that the client can test them.” Stainless steel ovens and refrigerators coated with Nanox will be protected from the risks of yellowing, a process resulting from the formation of undesirable oxides on the surface.

The project
The application of a ceramic coating on metallic surfaces (nº 04/08778-1); Modality Technological Innovation in Small Businesses (PIPE) Program; Coordinator Luiz Gustavo Pagotto Simões – Science; Investment R$ 74,728.63 (FAPESP)