matrices that support cell adhesion and growth are disclosed that deliver low heparin - binding affinity growth factor protein peptides in a controlled manner . these matrices comprise covalently or non - covalently bound heparin or heparin - like polymers , which serve to sequester the low heparin - binding affinity growth factor protein peptides within the matrix . the controlled release of some low heparin - binding affinity growth factor or peptides thereof occurs by degradation of some matrix component or dissociation of the low heparin - binding affinity growth factor protein peptides from the bound heparin . this differs from many controlled delivery devices in that release is not controlled solely by diffusion , and the rate of release may therefore be regulated by altering the rate of degradation of the matrix component or the amount of heparin bound within the matrix . the controlled release of such low heparin - binding affinity growth factor proteins such as ngf - β , nt - 3 and bdnf , is demonstrated . the invention also identifies basic domains that can be utilized to identify other low heparin - binding affinity growth factor protein peptides useful in delivery as part of the matrices described herein .