ferent chains 100 units long-smaller than the average peptide in any cell. The age of the universe, by contrast, is only 10$^{18 }$seconds old, and the total number of protons is about 10 80 . This is sufficient proof that only a very tiny fraction of possible sequences has been studied. All peptide and protein research to date, therefore, though informative, has but scratched the surface of what can be known about peptides for materials. 

Polypeptides are useful in strong, lightweight, functional and elastic materials. Examples of natural polypeptides include spider silk and muscle proteins. Embodiments of the subject invention can improve on such natural polypeptides in certain respects. Textiles, medical materials and dispos› able materials are included in areas of application for peptide materials. These materials can provide superior performance with regard to elasticity, energy conversion efficiency, strength per unit mass, biodegradability and for› eign body tissue reactions. In addition, compared to syn› thetic polymers, polypeptides-especially designed pep- tides----can be made sustainably. This is a feature that can be particularly useful in the field of advanced manufacturing. 

In an embodiment, the subject invention provides manu› facturing instructions regarding amino acid composition, degree of polymerization (DP) and solution conditions, which determine polymer structure and interactions. In some embodiments, the polypeptide processing is performed at ambient temperature under mild solution conditions, and the materials are biodegradable. 

In some embodiments, peptide polymers are water soluble and the amount of organic solvent needed in materials manufacturing is reduced or eliminated. In further embodi› ments, the random polypeptides are soluble in water and/or ethanol before crosslinking but insoluble in water after crosslinking. 

Additional aspects relate to the use of peptides with random amino acid sequences for materials fabrication. The randonmess embodied in the subject invention provides the ability to simultaneously make the synthetic peptides less like native globular proteins and more like the usual syn› thetic polymers in materials manufacturing and key regions of elastomeric proteins, such as for example, ti tin and resilin. 

In one aspect, the present invention provides a peptide› based material comprising cross-linked peptides with ran- dom amino acid sequences that are soluble in water or ethanol before crosslinking but insoluble in water after crosslinking. In one embodiment, the random amino acid sequences are fused with one or more elastin-like peptide (ELP). The peptide-based material may further comprise synthetic organic polymers. In some embodiments, the cross-linked peptides utilized in the peptide-based materials of the invention are synthesized by ring-opening polymer› ization. 

In some embodiments, the peptide-based material can be either a one-dimensional, two-dimensional, or three-dimen› sional material. Such one-dimensional materials are fiber materials, such as, but not limited to, anti-microbial fiber materials. Two-dimensional materials are film materials, such as, but not limited to, medical device coating films. Three-dimensional materials are molded materials. 

In one embodiment, the polypeptides of the subject inven› tion form entropic networks. The skilled artisan can appre› ciate that the materials of the subject invention, although random peptides, are nevertheless at least potentially hybrids of structure and function, not just one or the other. 

In some embodiments, the subject invention provides fusion peptides consisting of structural parts based on the present invention and functional parts based on biochemical research. 

In some embodiments, the subject invention provides a method for synthesizing statistical, linear peptides in solu› tion based on ring-opening polymerization of a-amino acid N-carboxyanhydrides, wherein growth occurs only by the probabilistic addition of monomers to active chain ends. In further embodiments, monomers are present throughout the process and polymer mass and yield are functions of mecha› nism and reaction particulars. In some embodiments, the product has a Poisson distribution of chain lengths, (Ne/Nrexp(-N), where N is DP and N is number-average DP, and N can range from 2 to >2,000. In some embodi› ments, short-range order is possible, long-range order is improbable and the synthesis from a heterogeneous mono› mer population is expected to yield chains of virtually identical amino acid composition. 

The subject invention is especially advantageous if monodisperse polymers and sequence specificity are optional and amino acid composition, predictability of water solubility, measurability of number-average mass and weight-average molecular mass, and therefore polydisper- sity index, and reproducibility of polymer production mate› rials processing are desired. 

In some embodiments, the subject invention provides control of polydispersity by reaction conditions and frac- tionation. 

In some embodiments, the subject invention provides a blend of different recombinant random sequences useful for material properties. In specific embodiments, the peptides are produced at high yield in photosynthetic bacteria. 

In other embodiments, the subject invention provides a solution-phase approach for random peptide production. The peptide polymers of the subject invention are polydisperse and have a low predicted crystallinity. 

In some embodiments, the subject invention provides electro spun fibers, including Poly(L-omithine) (PLO), PLEY, PLL and Poly(L-glutamic acid) (PGLA). 

In additional embodiments, the subject invention provides elastin-like peptides (ELPs) [(VPGVG)n] ([(SEQ ID NO:1) n]). In further embodiments, the ELPs are spinnable from water. The subject invention further provides peptides of a mole fraction of glutamic acid of 0.8-1.0, which corresponds to a maximum absolute value of average charge density for electro spinning from aqueous solution at pH 7. 

In some embodiments, the subject invention provides cast films, molded materials and foams. In further embodiments, the cast films and molded materials are made water-in› soluble by cross-linking. 

In additional embodiments, the subject invention provides an algorithm that relates elasticity and other aspects of materials processing to amino acid composition, degree of polymerization, pH, hydration and ionic strength. 

In some embodiments, the subject invention relates to the use of circular dichroism (CD) spectroscopy to analyze structural properties of peptides during multilayer film buildup. 

In other embodiments, the subject invention relates to the visualization of electrospun fibers by fluorescent micros› copy. 

In yet other embodiments, the subject invention relates to the use of a visible-range dye to quantify the efficiency of peptide crosslinking, wherein the decrease of dye absor› bance is a measure of the increased concentration of cross› linked polymers. 

