Surface contamination is a major concern in the design, fabrication, and application of biomaterials. In this work, a series of new adenine derivatives were synthesized in a three-step method with the goal of protecting the functional materials against microbial adhesion. Initially, 9-(chloroalkyl)-9H-purin-6-amine compounds were synthesized from adenine. Then, these compounds were reacted with potassium thiocyanate or potassium selenocyanate. In the last step, adenine derivatives incorporating a tetrazole ring were synthesized via the cycloaddition of sodium azide with thiocyano or selenocyano derivatives. The antimicrobial activity of the compounds was evaluated by using the minimal inhibitory concentration method. Furthermore, the effect of the compounds on pBR322 plasmid DNA was studied using gel electrophoretic mobility measurements. The antimicrobial assay showed that some of the synthesized compounds exerted vigorous antibacterial and antifungal activities. Further experiments indicated that seleno-adenine derivatives have higher antimicrobial and DNA effect than other derivatives. The surfaces activated by the adenine derivative demonstrated antibacterial activity resisting bacterial attachment in order to remove dead bacteria from the surface. All results showed that some of these adenine derivatives have an antibacterial activity and the potential for further applications, for example as a smart surface coating that prevents bacterial adhesion to biomaterials.