The present invention relates to an artificial nucleus pulposus implant that is injected minimally invasively into the nucleus cavity of the annulus fibrosus to restore the normal anatomical and physiological function of the spine in the affected disc segment. In one aspect of the invention, a device is disclosed for delivering a phase changing biomaterial to a tissue site, the device comprising a dispenser including (i) a plunger having a proximal portion and a distal portion, an inlet end and an outlet end, (ii) a dispensing actuator attached to the proximal portion of the plunger, and (iii) a cartridge adapted to be inserted into the inlet end of the plunger for containing the phase changing biomaterial in a fluid state. The dispenser may be mechanically, pneumatically or hydraulically actuated. The dispenser may further comprise a nozzle attached to the cartridge for dispensing the biomaterial to the tissue site. In another aspect, the device may further comprise a tissue cavity access unit providing a conduit having an inlet end in fluid communication with the nozzle, and an outlet end adapted to deliver the biomaterial to the tissue site. The biomaterial may transition from the fluid state to a solid state after a set amount of time, a temperature change or an exposure to an external stimuli such as radiation, UV light or an electrical stimuli. The cartridge may be a dual-chambered cartridge for storing different fluid biomaterials in the two chambers. In another aspect of the invention, a process for producing the artificial nucleus pulposus implant in the nucleus cavity of the annulus fibrosus is disclosed, the process comprising the steps of (a) obtaining access to the nucleus cavity; (b) injecting the artificial nucleus pulposus into the nucleus cavity; and (c) permitting the biomaterial to transition from a fluid state to a solid state in-situ after a given condition.