# The Modification of Titanium Surface by Decomposition of Tannic Acid Coating
## 1 Introduction  
The development of civilization, alongside sedentary lifestyles, poor nutrition, living life at a constant \"run\" and the accompanying stress, have definitely had a negative impact on the health of society. Due to changing lifestyles and the ensuing deterioration of health, we are becoming more vulnerable to damage to bones, muscles, ligaments and joints, and thereby, increasingly subjected to degenerative changes and diseases. Musculoskeletal diseases represent the leading cause of disability around the globe and incur economic burdens in the form of substantial costs for societal healthcare and for social support for individuals. Moreover, society can be described as aging (an increase in the proportion of older people), with the pace of aging much more rapid than it was in the past [1]. The increase in the number of elderly people in society results from two basic phenomena: the decrease in the number of births and the increase in life expectancy. Numerous diseases of the musculoskeletal system accompany this phenomenon, and injuries related to various sports, traffic accidents and overweight are becoming serious social, economic and medical problems [2]. Orthopedic trauma associated with road traffic accidents, sports injuries, collision or sudden falls, is one of the major causes of mortality and hospitalization, which results in a waste of human and financial resources. In some ways, through the development of knowledge, humans have always attempted to search for new solutions, which is why the development of medicine as ascience, in conjunction with the development of biological sciences and clinical methods, allows us to find new biomaterials to be used as implants and allows us to improve the existing properties of the materials used [3]. The proposed solutions are aimed at improving the living comfort of society. The growing awareness of the consumer also affects the need to improve products, because when it comes to health, the latest scientific achievements are often preferred [4]. Due to the extension of life expectancy, the demand for implants used in orthopedics is growing year by year. The global medical implant market with a value of about USD 95 billion in the year 2022 is projected to reach about USD 145 billion by the year 2030 [5]. The global market size of orthopedic implants is estimated to reach USD 79.5 billion, which is almost twice the market size in 2019 [6]. Implants are designed to support damaged tissue or replace diseased or damaged parts of the musculoskeletal system where the loads are very heavy and the load on the joints/muscles is variable [7]. This means that the material must have high strength properties and high resistance to various types of corrosion. At the same time, an important factor influencing the properties of the material must be its biotolerance [8]. The contact of a material with the desired biotolerance with a living cell does not cause any acute or chronic reactions or inflammations of the surrounding tissue [9]. In general, titanium and its alloys are widely used for orthopedic, dental and other biomedical applications due to their low specific weight, high mechanical strength, reduced value of elastic modulus (lower than conventional orthopedic implant materials, such as stainless steel and Co-Cr alloys), good corrosion resistance in most corrosive environments (including tissue environments) and non-toxic behavior. The successful course of implant placement in a living organism is determined by \"a direct structural and functional connection between the bone and the surface of the loaded implant\". In spite of these positive aspects, the metallic Ti surfaces are bioinert, rendering the surfaces less responsive to cell attachment and proliferation and effectuating the surfaces to be more prone to bacterial infections and subsequent biofilm formations.