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Relief for burns

Hydrogel dressing lessens pain, prevents skin from drying up and fights bacteria

The treatment for burns should shortly have a new ally. The novelty arose at the Chemistry Institute of the University of São Paulo (IQ-USP), where researchers have developed a dressing of hydrogel strengthened with polypropylene fibers, a plastic material, ideal for treating burns. Hydrogels are polymeric materials, with a consistency similar to gelatin, which retain water in their structure. The bandages made with this biomaterial, which are also called membranes, are no novelty in the market, but their mechanical fragility prevents them from being used in a generalized way in hospitals, because they burst easily when handled. The doctors also complain that the dressing is too small and does not cover large areas of the body.

With the polypropylene reinforcement developed at USP, the dressings can be made to any size, and not just the standard size of 8 by 15 centimeters. The perfecting of the product was the work of chemist Luiz Henrique Catalani and his team. They used the hydrogel created by Polish researcher Janus Rosiak, the technology for which was transferred at the beginning of the 1990’s to the Nuclear and Energy Research Institute (Ipen).The hydrogel bandages are made up of water (92% of their mass) and polymers (the remaining 8%), with their main component being polyvinylpyrrolidone (PVP).

The biggest advantage over the traditional dressings, made of gauze, is that they reduce the pain caused by the burn. “This sensation occurs because of the exposure of nerve endings in the wounds. By keeping the burnt area moist, the pain diminishes by over 90% and brings great relief to the patients”, explains Catalani. Another advantage of hydrogel is that it speeds up the process scar formation, since it keeps the burn hydrated all the time. Furthermore, as it is impermeable to microorganisms – the web of the membrane is in the order of from 5 to 7 nanometers (millionth parts of a millimeter) -, it prevents infection by bacteria. At the same time, the wound is kept aired, because the dressing is permeable to oxygen.

Gel sandwich
To develop a bigger, strengthened membrane, Catalani tested several materials until coming across polypropylene fiber. “But it had a problem: it was hydrophobic, incompatible with the aqueous medium. The solution was to make a copolymer (a molecular joining of two polymers) with a hydrophilic material, which absorbs water. The resulting product then became compatible with hydrogel. From then on, we did an assembly with two outer layers of PVP and an inner one of polypropylene”, Catalani explains. Tests indicated that the new dressing is eight times more resistant than the original one.

The result achieved at the IQ-USP was transformed into a patent filed at the National Institute of Industrial Property (INPI), with funding from FAPESP’s Nucleus for Patenting and Licensing Technology (Nuplitec). Catalani is now negotiating with the Biolab-Sanus pharmaceutical company for the reinforced membrane to be produced commercially. The laboratory is a partner of Ipen in the development of the unreinforced hydrogel membrane. Twenty thousand prototypes of this membrane have been undergoing tests since March this year at 20 hospitals in Brazil. “Depending on the results, Biolab-Sanus will kick off commercial production, but no date has been defined”, explains chemical engineer Ademar Lugão, the researcher at Ipen responsible for bringing the technology for hydrogel dressings to Brazil.

Developing the dressing was not the only contribution from Professor Catalani and his team for the treatment of burns. They also created a cheaper and more accessible way for producing the membranes. By the conventional system, used by Ipen, the polymeric solution in a liquid state needs to be exposed to high-energy radiation – a beam of electrons or gamma radiation – to acquire the consistency of gel.

This method is highly effective, because it brings about simultaneously reticulation (a formation of crossed reactions between the polymeric chains that transform the aqueous solution into gel) and sterilization of the dressing, but it has a problem: there are few companies and institutions that have the necessary equipment for doing it. “In the light of this limitation, we decided to create another system for producing it, without high energy radiation”, Catalani explains. “We discovered, then, that it was possible to produce the hydrogel dressings with ultraviolet (UV) radiation using PVP, something unprecedented in the production of hydrogel for biomedical use.”

Simple and cheap
When it was first discovered, the process would take a few hours, which made it impracticable commercially. The technique was perfected and the processing time reduced, on a laboratory scale, to less than 30 minutes. “That is still far longer than the time with high energy radiation, which is instantaneous, but it does have countless advantages. It is cheap, simple and accessible.” With it, businesspersons interested in manufacturing the membranes will be able to carry out the whole process on their own premises, which is not possible in the other system, because high-energy irradiation is necessarily outsourced. In the next few months, Catalani hopes to file the patent for the dressing with UV radiation with the INPI and then to negotiate commercial production.

Catalani and his team also developed another technology for producing hydrogels, following the reaction from oxidation-reduction. The big difference between the dressings formed by this process and the traditional ones is that they do not have a predefined format. The membrane molds itself to the area to which is applied and is ideal for regions of the body like the hands and toes. It works by placing the PVP onto the body, without having irradiated it, in the affected area. Next, a substance is sprinkled over the product, bringing about oxidation-reduction and transforming it into gel. “As far as I know, this hydrogel is without precedent in the world.” It is being finalized and awaits the results of the tests for toxicity done by the Adolfo Lutz Institute.

The project
Dressing Made Up of Polyvinylpyrrolidone Reinforced by Polypropylene Fibers Grafted with Acrylic Monomer (nº 01/13293-9); Modality Intellectual Property Support Program (PAPI); Coordinator Luiz Henrique Catalani – IQ-USP; Investment R$ 6,000.00