The present invention relates to a biopolymer, bioactive and totally biocompatible, very fluid at ambient temperature, capable of gelling in a sudden manner at 37° C., forming a solid implant, structurally integral and continuous having high mechanical properties. The biopolymer comprises at least a bioactive domain capable of directing in a precise manner the formation of a solid or semisolid implant. Furthermore the invention relates to any of the nucleic acids encoding the amino acid sequence of the biopolymer, implants, pharmaceutically acceptable vehicles, uses thereof, and a method of synthesis thereof.