. . . "L-arginine, also known as R, Arg, or 2-amino-5-guanidinovaleric acid, is an amino acid having a formula Polymers and/or oligomers of L-, D-, and D, L-arginine that can be used are referred to as ???PArg??? and comprise a plurality of repeating monomeric amino acid units connected with peptide bonds, each unit including a 1-guanidinopropyl radical having the structure ???CH2???CH2???CH2???NH???C(NH" .