Abstract:
Methods for forming repeat protein polymers and utilizing the repeat protein polymers to form inorganic structures are provided. The inorganic structures may have features on the nanoscale, and the structures generally do not have the repeat protein polymers incorporated therein. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that is will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72( b ).

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority to U.S. Provisional Application No. 60/381,913, filed May 20, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to biomineralization and more specifically, to the formation of inorganic structures using repeat protein polymers as a template and catalyst for the formation.  
           [0003]    The formation of highly ordered inorganic materials on a surface has become increasingly important in a variety of fields such as electronics and photonics. The formation of inorganic materials on a nanometer scale is also becoming increasingly desirable as device sizes are reduced. However, the formation of nanometer scale inorganics generally requires extreme conditions such as high pressure, temperature, or pH. Many biological organisms are able to form inorganic materials under ambient conditions in a process known as biomineralization. The structures of inorganic materials formed by biological organisms are highly controlled from the nanometer scale to the macroscopic scale.  
           [0004]    For example, the condensation of tetraethoxysilane (TEOS) in a manufacturing setting may require an extreme pH, high temperature, and/or the use of surfactants. Thus, the need remains in the relevant art for a mode of biomineralization that may be utilized to form desired minerals having highly ordered structures at ambient conditions on a commercially viable scale.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention meets that need by applying recombinant repeat sequence protein polymers to a substrate to act as catalysts and templates for the formation of inorganic structures.  
           [0006]    In accordance with an embodiment of the present invention a method of forming an inorganic structure is provided. The method comprises providing a substrate having a repeat protein polymer thereon, the repeat protein polymer having the formula:  
           T y [(A n ) x (B) b (A′ n′ ) x′ (B′) b′ (A″ n″ ) x″ ] i T′ y′   
           [0007]    wherein:  
           [0008]    T is an amino acid sequence of from about 1 to about 100 amino acids, which may be any sequence comprising fewer than about 20% of the total number of amino acids in the repeat protein copolymer;  
           [0009]    y is 0or 1;  
           [0010]    T′ and y′ are the same as or different from T and y respectively;  
           [0011]    A is an individual unit of a repeat amino acid sequence;  
           [0012]    n is an integer of at least 2 and not more than 250;  
           [0013]    x is 0 or an integer of at least 1 and varies with the number of different amino acids in A so as to provide for at least 30 amino acids in each A repeat sequence;  
           [0014]    A′, n′, and x′ are the same as or different from A, n, and x respectively, at least one being different;  
           [0015]    A″, n″, and x″ are the same as or different from A, n, and x respectively, at least one being different;  
           [0016]    B is any amino acid sequence of about 4 to about 50 amino acids;  
           [0017]    B′ and b′ are the same as or different from B and b respectively; and  
           [0018]    i is 1 to 100; and  
           [0019]    exposing the substrate to a precursor comprising an inorganic species such that the repeat protein polymer catalyzes the formation of an inorganic structure on the substrate. Additionally, the present invention includes the inorganic structure made by the method.  
           [0020]    In accordance with another embodiment of the present invention, a method of forming an inorganic structure is provided. The method comprises providing a first repeat protein polymer having the formula:  
           T y [(A n ) x (B) b (A′ n′ ) x′ (B′) b′ (A″ n″ ) x″ ] i T′ y′   
           [0021]    wherein:  
           [0022]    T is an amino acid sequence of from about 1 to about 100 amino acids, which may be any sequence comprising fewer than about 20% of the total number of amino acids in the repeat protein copolymer;  
           [0023]    y is 0or 1;  
           [0024]    T′ and y′ are the same as or different from T and y respectively;  
           [0025]    A is an individual unit of a repeat amino acid sequence;  
           [0026]    n is an integer of at least 2 and not more than 250;  
           [0027]    x is 0 or an integer of at least 1 and varies with the number of different amino acids in A so as to provide for at least 30 amino acids in each A repeat sequence;  
           [0028]    A′, n′, and x′ are the same as or different from A, n, and x respectively, at least one being different;  
           [0029]    A″, n″, and x″ are the same as or different from A, n, and x respectively, at least one being different;  
           [0030]    B is any amino acid sequence of about 4 to about 50 amino acids;  
           [0031]    B′ and b′ are the same as or different from B and b respectively; and  
           [0032]    i is 1 to 100;  
           [0033]    contacting a substrate with the first repeat protein polymer such that the substrate has the first repeat protein polymer thereon; and exposing the substrate having the first repeat protein polymer thereon to a first precursor having an inorganic species such that a first inorganic structure forms on the substrate in areas having the first repeat protein polymer. The method may further comprise providing a second repeat protein polymer in contact with said first inorganic structure, said second repeat protein polymer having the formula:  
           T y [(A n ) x (B) b (A′ n′ ) x′ (B′) b′ (A″ n″ ) x″ ] i T′ y′   
           [0034]    wherein:  
           [0035]    T is an amino acid sequence of from about 1 to about 100 amino acids, which may be any sequence comprising fewer than about 20% of the total number of amino acids in the repeat protein copolymer;  
           [0036]    y is 0 or 1;  
           [0037]    T′ and y′ are the same as or different from T and y respectively;  
           [0038]    A is an individual unit of a repeat amino acid sequence;  
           [0039]    n is an integer of at least 2 and not more than 250;  
           [0040]    x is 0 or an integer of at least 1 and varies with the number of different amino acids in A so as to provide for at least 30 amino acids in each A repeat sequence;  
           [0041]    A′, n′, and x′ are the same as or different from A, n, and x respectively, at least one being different;  
           [0042]    A″, n″, and x″ are the same as or different from A, n, and x respectively, at least one being different;  
           [0043]    B is any amino acid sequence of about 4 to about 50 amino acids;  
           [0044]    B′ and b′ are the same as or different from B and b respectively; and  
           [0045]    i is 1 to 100; and  
           [0046]    exposing the second repeat protein polymer to a second precursor comprising an inorganic species such that a second inorganic structure forms on the first inorganic structure.  
         DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
         [0047]    The present invention utilizes recombinant repeat protein polymers containing repeating units to serve as templates and catalysts for biomineralization. The repeating units may be of natural structure supporting materials such as silk, elastin, and collagen, or the repeating units may be of synthetic structure. For example, the present invention involves synthesizing the repeat protein polymers, placing the repeat protein polymers on a substrate, and exposing the repeat protein polymers to a precursor to form inorganic structures on the substrate.  
           [0048]    Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth as used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless otherwise indicated, the numerical properties set forth in the following specification and claims are approximations that may vary depending on the desired properties sought to be obtained in embodiments of the present invention. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from error found in their respective measurements.  
           [0049]    The recombinant repeat protein polymers of the present invention are comprised of naturally or non-naturally occurring repeating units. There are more than six hundred repeat protein sequences known to exist in biological systems as of the filing of this application. Example include such well proteins containing repeat amino acid sequences as abductin, elastin, byssus, flagelliform silk, dragline silk, gluten high molecular weight (HMW) subunit, titin, fibronectin, leminin, and collagen. Additionally, synthetic repeating units may be utilized. Individual repeating units may be from 3 to 30 amino acids, and will usually have the same amino acid appearing at least twice in the same unit. For example, individual units of a repeat amino acid sequence may be from about 3 to 8 amino acids. Different unit combinations may be joined together to form a block copolymer or alternating block copolymer. The copolymers may have the following formula:  
           T y [(A n ) x (B) b (A′ n′ ) x′ (B′) b′ (A″ n″ ) x″ ] i   T′   y′   
           [0050]    wherein:  
           [0051]    T is an amino acid sequence of from about 1 to about 100 amino acids, for example, 1 to 60 amino acids, which may be any sequence, generally being fewer than 20% of the total number of amino acids in the repeat protein copolymer;  
           [0052]    y is 0 or 1;  
           [0053]    T′ and y′ are the same as or different from T and y respectively, wherein the analogous symbols have the same definition as their counterparts;  
           [0054]    A is an individual unit of a repeat amino acid sequence;  
           [0055]    n is an integer of at least 2 and not more than 250;  
           [0056]    x is 0 or an integer of at least 1 and will vary with the number of different amino acids in A so as to provide for at least 30 amino acids in each A repeat sequence;  
           [0057]    A′, n′, and x′ are the same as or different from A, n, and x respectively, at least one being different, wherein the analogous symbols have the same definition as their counterparts;  
           [0058]    A″, n″, and x″ are the same as or different from A, n, and x respectively, at least one being different, wherein the analogous symbols have the same definition as their counterparts;  
           [0059]    B is any amino acid sequence of 4 to 50 amino acids, usually being a functional sequence that results in a biological or chemical function or activity;  
           [0060]    b is 0 to 3;  
           [0061]    B′ and b′ are the same as or different from B and b respectively, wherein the analogous symbols have the same definition as their counterparts; and  
           [0062]    i is 1 to 100, for example, 1 to 50 or 1 to 30.  
           [0063]    Additionally, the protein polymer may have amino acid sequences that link the repeating A, A′, and A″ units or amino acid sequences that link between the individual A, A′ or A″ units. These linking sequences may be from 1 to 10 amino acids and serve to link the repeating units. These repeat polymers can be synthesized by generally recognized methods of chemical synthesis [L Andersson et. al.,  Large-scale synthesis of peptides , Biopolymers 55(3), 227-50 (2000)], genetic manipulation (J. Cappello, Genetically Engineered Protein Polymers, Handbook of Biodegradable Polymers, Domb, A. J.; Kost, J.; Wiseman, D. (Eds.) Harvard Academic Publishers, Amsterdam. Pages 387-414.), and enzymatic synthesis [C. H. Wong &amp; K. T. Wang,  New Developments in Enzymatic Peptide Synthesis , Experientia 47(11-12), 1123-9 (1991)]. For example, repeat protein polymers useful in the practice of the present invention may be synthesized using the methods described in U.S. Pat. Nos. 5,243,038 and 6,355,776, the disclosures of which are incorporated by reference herein. In another example, a peptide may be synthesized utilizing non-ribosomal peptide synthase (H. V. Dohren, et al., Multifunctional Peptide Synthase, Chem.Rev 97, 2675-2705(1997).  
           [0064]    In accordance with an embodiment of the present invention, repeat portions of elastic proteins may be used as the A units. The term “elastic protein” applies to many structural proteins with diverse functions and mechanical properties. Elastic implies the property of elasticity, or the ability to deform reversibly without loss of energy; so elastic proteins should have high resilience. Another meaning for elastic is ‘stretchy’, or the ability to be deformed to large strains with little force. Thus, elastic proteins may have low stiffness. The combination of high resilience, large strains and low stiffness is characteristic of rubber-like proteins (e.g. resilin and elastin) that function in the storage of elastic-strain energy. Other elastic proteins play very different roles and have very different properties. Collagen fibers provide exceptional energy storage capacity but are not very stretchy. Mussel byssus threads and spider dragline silks are also elastic proteins because, in spite of their considerable strength and stiffness, they are remarkably stretchy. The combination of strength and extensibility, together with low resilience, gives these materials an impressive resistance to fracture (i.e. toughness).  
           [0065]    Individual units of particular interest include units found in silk-, elastin-, collagen-, abductin-, byssus-, gluten-, titin-, extensin-, and fibronectin-like proteins. Silk-like proteins have a repeating unit of SGAGAG (G=glycine; A=alanine; S=serine) (SEQ ID NO: 1). This repeating unit is found in naturally occurring silk fibroin protein, which can be represented as GAGAG(SGAGAG) 8 SGAAGY (Y=tyrosine) (SEQ ID NO: 2). Elastin-like proteins have a base repeating unit of GVGVP (V=valine; P=proline) (SEQ ID NO:3). This repeating unit may be found in naturally occurring elastin. Collagen-like proteins have repeating units of G-x-y (x=any amino acid, often alanine or proline; y=many amino acid, often proline or hydroxy-proline). Abductin-like proteins have a base repeating unit of GGFGGMGGGx (F=phenylalanine; M=methionine) (SEQ ID NO: 4). Byssus-like proteins have a repeating unit of (GPGGG) (SEQ ID NO: 5). Gluten-like proteins of the high molecular weight subunit have repeating units of PGQGQQ (SEQ ID NO: 6), GYYPTSPQQ (SEQ ID NO: 7), and GQQ (Q=glutamine; Y=tyrosine; T=threonine) (SEQ ID NO: 8). Titin-like proteins have a repeating units of PPAKVPEVPKKPVPEEKVPVPVPKKPEA (K=Lysine, E=Glutamic Acid) (SEQ ID NO: 9) and are found in the heart, psoas, and soleus muscle. Extensin-like proteins have repeating units of SPPPPSPKYVYK (SEQ ID NO: 10). Fibronectin-like proteins have repeating units of RGDS (R=arginine; D=aspartic acid) (SEQ ID NO: 11).  
           [0066]    Additional repeating units of interest are found in gliadin, glue polypolypeptide, ice nucleating protein, keratin, mucin, RNA polymerase II, and resilin. Gliadin has a repeating unit of PQQPY (SEQ ID NO: 12). The glue polypeptide has a repeating unit of PTTTK (SEQ ID NO: 13). The ice nucleating protein has a repeating unit of AGYGSTGT (SEQ ID NO: 14). Keratin has repeating units of YGGSSGGG (SEQ ID NO: 15) or FGGGS (SEQ ID NO: 16). Mucin has a repeating unit of TTTPDV (SEQ ID NO: 17). RNA polymerase II has a repeating unit of YSPTSPS (SEQ ID NO: 18). Additionally, resilin, a rubber-like protein contains repeating units.  
           [0067]    Copolymers utilizing these natural repeating units may have their properties altered by appropriate choice of different units, the number of units in each multimer, the spacing between units, and the number of repeats of the multimer combination assembly. The spacing between units refers to the amino acid sequences represented by B or B′ in the above formula. For example, the copolymers may be combinations of silk units and elastin units to provide silk-elastin copolymers having properties distinctive from polymers having only the same monomeric unit. In a further example, silk-elastin repeat protein polymers may have their solubility decreased as the number or silk units (SEQ ID NO: 1) is increased. Additionally, altering the spacing, B, between individual repeat units, A, may affect the rate of precipitation of an inorganic precursor as discussed herein.  
           [0068]    In accordance with an embodiment of the present invention, the repeat protein polymers may have an overall cationic charge, and the overall cationic charge may enhance the ability of the repeat protein polymer to catalyze the formation of inorganic structures as discussed hereafter. Overall cationic charge shall be understood as referring to the net cationic (+) charge present after the summation of individual amino acid residue charges at a given pH and temperature. For example, the pH may be 7 and the temperature may be 20° C. In accordance with another embodiment of the present invention, the repeat protein polymers may have silk units (SEQ ID NO: 1) and/or collagen like units, and repeat protein polymers having these units may have their ability to catalyze the formation of inorganic structures enhanced. In accordance with another embodiment of the present invention, the repeat protein polymers may have at least one or a plurality of lysine residues.  
           [0069]    In accordance with an embodiment of the present invention, the repeat portion of the repeat protein polymers, [(A n ) x (B) b (A′ n′ ) x′ (B′) b′ (A″ n″ ) x″ ] i , may be: head-[(GAGAGS) 2 (GVGVP) 3 GKGVP (GVGP) 4 (GAGAGS) 2 ] 13 -tail (SEQ ID NO: 19); head-[(GVGVP) 4 GEGVP(GVGVP) 3 (GAGAGS) 4 ]-tail (SEQ ID NO: 20); head-[(GAGAGS) 3 (GVGVP) 3 GKGVP(GVGVP)  4 ] 12 -tail (SEQ ID NO 21); head-[(GAHGPAGPK) 2 (GAQGPAGPG) 24 (GAHGPAGPK) 2 ] 4 -tail (SEQ ID NO: 22); head-[(GVGVP) 4 GKGVP(GVGVP) 3 (GAGAGS) 3 ] 12 -tail (SEQ ID NO: 23); head-[(GAPGTPGPQGLPGSP) 4 ] 13 -tail (SEQ ID NO: 24); and head-[(GAPGAPGSQGAPGLQ) 4 ] 13 -tail (SEQ ID NO: 25). The head and tail portions of the repeat sequences correspond to T and T′ and may be any suitable sequence. For example, the head and tail sequences may signal the start and stop for the repeat protein polymer. Suitable head sequences include, but are not limited to, MDPVVLQRRDWENPGVTQLNRLAAHPPFASDPM (SEQ ID NO: 26). Suitable tail sequences include, but are not limited to, GAGAMDPGRYQDLRSHHHHHH (SEQ ID NO: 27), MDPGRYQDLRSHHHHHH (SEQ ID NO: 28), MDPGRYGLSAGRYHYQLVWCQK (SEQ ID NO: 29), MDPTRYGLSAGRYHYQLVWCQK (SEQ ID NO: 30), MDPGRYQLSAGRYHYQLVWCQK (SEQ ID NO: 31), MDPTRYQLSAGRYHYQLVWCQK (SEQ ID NO: 32), GAGAMDPGRYQDLRSHHHHHH (SEQ ID NO: 33), and MDPGRYGDLRSHHHHHH (SEQ ID NO: 34).  
           [0070]    Once the repeat protein polymer has been synthesized and purified as needed, the repeat protein polymer or a plurality of repeat protein polymers are generally applied to a substrate or a substrate is contacted with the repeat protein polymers. The repeat protein polymers may be the different or the same. For example, one, two, or three of the repeat protein polymers may be different. The substrate may be any suitable surface such as steel, glass, silicon, mica, graphite, plastic, teflon or the like. While not wishing to be bound by theory, it is believed that once applied to the substrate, many of the repeat protein polymers may exhibit desirable surface properties due to beta sheet structures and the ability to form self-assembled monolayers (SAM&#39;s). SAM&#39;s are formed by the spontaneous aggregation and organization of the protein into a monolayer. The SAM may be in the form of a patterned deposition due to the use of repeat sequences. The SAM is at or near thermodynamic equilibrium, and therefore the SAM tends to reject defects. The presence of SAMs may be confirmed using atomic force microscopy or scanning electron microscopy.  
           [0071]    The repeat protein may be applied to a substrate using a variety of techniques. For example, the protein may be spin coated on the substrate. However, it may be desirable to form an ordered and patterned structure on the substrate. Therefore, techniques such as soft lithography, rapid printing or photolithography may be utilized to form a pattern of protein on a substrate. For example, soft lithography or rapid printing can be utilized to form the pattern.  
           [0072]    Soft lithography is a non-photolithographic technique useful for carrying out micro- and nanofabrication. Soft lithography may produce patterns and structures having feature sizes ranging from about 30 nm to about 100 μm. Soft lithography generally utilizes an elastomeric stamp or mold (soft lithographic stamp) with patterned relief structures on its surface used to generate the desired pattern. In one embodiment, an elastomeric stamp may be formed using a master mold. The stamp is “inked” with the repeat protein polymer in a solution and a substrate is contacted with the stamp. A pattern of SAM protein is formed on the substrate in the areas where the relief structures of the stamp contacted the substrate. Examples of suitable soft lithographic stamps are found in published U.S. patent application Ser. Nos. 20010027570 and 20010013294, the disclosures of which are incorporated by reference herein. Alternatively, a mold may be formed and placed in contact with a substrate. A protein solution is then placed at one end of the mold, and channels in the mold fill by capillary action to form a pattern after the mold is removed. Additionally, the substrate itself may be patterned by soft lithography, and the protein may then be applied to the substrate to fill the pattern. For example, placing a mold on the substrate and filling it with a prepolymer may pattern the substrate. U.S. Pat. No. 6,368,877 discloses several methods of forming patterned SAMs using soft lithography and is incorporated by reference herein.  
           [0073]    In rapid printing, a self assembling “ink” comprising the protein in solution is used with rapid printing procedures to form patterned structures in a very short period of time. Suitable rapid printing procedures include pen lithography, ink-jet printing, and dip-coating. The rapid printing procedures use the ink to form a desired pattern on suitable substrates. The ink thus forms patterned SAMs that define functional, hierarchically organized structures in seconds. Suitable rapid printing techniques and apparatus are described in Hongyou Fan,  Rapid Prototyping of Patterned Functional Nanostructures , Nature 405, 56- 60 (2000), which is incorporated by reference herein.  
           [0074]    Once the repeat protein polymer has been placed on or applied to the substrate or the substrate has been contacted with the repeat protein polymer, the substrate is exposed to a precursor containing a desired inorganic species, and the repeat protein polymer catalyzes the formation of an inorganic structure on the substrate. For purposes of defining and describing the present invention, the terms “formation”, “formed”, and “forms” shall be understood as referring the deposition of an inorganic structure on a substrate. The repeat protein polymer on the surface of the substrate acts both as a catalyst and a template in the formation of a desired inorganic structure from the precursor. The inorganic structures are generally formed only in areas of the substrate having at least one repeat protein polymer. For example, the polymer may be exposed to a silicon containing precursor to cause the formation of silica on the substrate. Examples of silicon containing precursors include, but are not limited to, tetraethoxysilane solutions (TEOS), TEOS dissolved in an acid to make a silicic acid solution, 3-aminopropyltriethoxysilane, and phenyltriethoxysilane. The repeat protein polymer acts as a catalyst in the reaction, and therefore does not form a silica-protein composite material. Additionally, the repeat protein polymer acts as a template for the formation of the silica because silica formation will occur only in areas that contain the repeat protein polymer. Thus, a silica structure may be formed that conforms to the pattern formed on the surface by the repeat protein polymer. Alternatively, the precursor may contain other inorganic species. For example, the precursors may contain zirconium, silver, copper, cadmium, tantalum, yttrium, iron, titanium, cobalt or calcium species to form their respective metal, salt, and minerals or possible combinations of hybrid structures on the substrate. For example, suitable precursors include, but are not limited to, yttriumethoxide, silver nitrate, and calcium chloride. In one embodiment, the inorganic structures may have features on the order of about 1 to about 999, about 1 to about 250, or about 1 to about 100 nanometers. It will be understood that a plurality of precursors may be used in the present invention, and it will be further understood that the plurality of precursors may be the same or different precursors. Thus, a product comprising nanopatterned structures may be formed by the methods of the present invention.  
           [0075]    For example, self-assembling nanometer-sized aggregates of mesoporous fibrous silica particles may be formed when a hydrolyzed TEOS solution is used in conjunction with repeat protein polymers of the present invention. Mesoporous fibrous silica may refer to porous material having wall portions defining meso-porus sized channels having a mean diameter of between about 15 Angstrom to about 100 Angstrom and a narrow diameter distribution of approx˜&lt;30 Angstrom, the silica material having a void volume from said meso-pore sized channels of approximately˜&gt;0.1 cm3/g (Philos Trans R Soc Lond B Biol Sci Feb. 28, 2002 ;357(1418):121-32). These silica particles may be in the form of fibrous silica with the fibers being on the nanometer scale in size. Mesoporous fibrous silica particles may be used in a variety of applications. For example, the particles may be used for catalysis, memory storage, replication, heat reflecting materials, thermal insulators, and optical reflectors.  
           [0076]    The inorganic structure may be formed under ambient conditions, such as room temperature and atmospheric pressure, which is particularly advantageous when the substrate cannot be exposed to high temperatures or pressures. After the formation of the inorganic structure, subsequent layers of repeat protein polymer and inorganic material may be formed in accordance with the above processes. In this manner, stacked three-dimensional structures may be formed. Thus, the inorganic structures formed by the methods of the present invention may be used in a variety of applications such as electronics, photonics, and nanocomposite materials.  
           [0077]    In order that the invention may be more readily understood, reference is made to the following examples, which are intended to be illustrative of the invention, but are not intended to be limiting in scope. 
       
    
    
     EXAMPLE 1  
       [0078]    A genetically engineered silk-elastin copolymer SELP47K (SEQ ID NO: 19) was isolated and purified from  E. coli  bacteria. The  E. coli  containing the SELP47K (SEQ ID NO: 19) recombinant DNA was obtained from Protein Polymer Technologies, Inc. of San Diego, Calif. The SELP47K (SEQ ID NO: 19) had a general structure of:  
                                           head-[(GAGAGS) 2 (GVGVP) 3 GKGVP   (SEQ ID NO: 19)               (GVGP) 4 (GAGAGS) 2 ] 13 -tail.          
 
         [0079]    The copolymer contained 780 amino acids in the repeating unit.  
         [0080]    Bovine albumin serum (BSA) was purchased from Sigma Aldrich, St. Louis, Mo. A 13% solution of SELP47K (SEQ ID NO: 19) in water was prepared. A 13% solution of BSA in water was prepared. A stainless steel coupon was spin coated with the SELP47K (SEQ ID NO: 19) solution to a thickness of 2 μm to form a SELP47K (SEQ ID NO: 19) protein film. A stainless steel coupon was spin coated with the BSA solution to a thickness of 2 μm to form a BSA protein film.  
         [0081]    A hydrolyzed TEOS solution was made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the TEOS solution was filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The TEOS assay solution was placed on the film of both the SELP47K (SEQ ID NO: 19) and BSA and in a corner of both steel coupons where no protein film was present.  
         [0082]    It was observed that silica precipitation completed within one minute on the SELP47K (SEQ ID NO: 19) film. No silica precipitation was observed on the BSA film. Additionally, no silica precipitation was observed on the uncoated corners of the steel coupons. The SELP47K (SEQ ID NO: 19) film was analyzed to confirm the silica precipitation by removing the white solid precipitated over the SELP47K (SEQ ID NO: 19) film mechanically and dissolving the precipitated silica in NaOH and reacting the solution with molybdic acid to observe the color.  
       EXAMPLE 2  
       [0083]    A 10-20% solution of the SELP47K (SEQ ID NO: 19) obtained in Example 1 in water was prepared. A stainless steel coupon was spin coated with the SELP47K (SEQ ID NO: 19) solution to a thickness of 2 μm to form a SELP47K (SEQ ID NO: 19) protein film. A yttrium ethoxide solution was placed on the film of the SELP47K (SEQ ID NO: 19). Ytrrbia precipitation was observed immediately on the protein polymer film whereas no such precipitation was seen when dropped directly on the metal coupon having no SELP47K (SEQ ID NO: 19) protein polymer film.  
       EXAMPLE 3  
       [0084]    A SELP37K (SEQ ID NO: 21) copolymer having a structure of: head-[(GAGAGS) 3 (GVGVP) 3 GKGVP(GVGVP) 4 ] 12 -tail (SEQ ID NO 21) may be obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  may be prepared in accordance with the methods described un U.S. Pat. Nos. 5,243,038 and 6,355,776.  
         [0085]    A 10-20% solution of SELP37K (SEQ ID NO: 21) in water was prepared. A stainless steel coupon was spin coated with the SELP37K (SEQ ID NO: 21) solution to a thickness of 2 μm to form a SELP37K (SEQ ID NO: 21) protein film. A hydrolyzed TEOS solution was made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the hydrolyzed TEOS solution was filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. A drop of TEOS assay solution was placed on the film of the SELP37K (SEQ ID NO: 21). Silica precipitation was observed. It was observed that within five minutes silica precipitation completed on the SELP37K (SEQ ID NO: 21) film. No silica precipitation was observed on the control BSA film. Additionally, no silica precipitation was observed on the uncoated corners of the steel coupons. The SELP37K (SEQ ID NO: 21) film was further analyzed to confirm the silica precipitation by removing the white solid precipitated over the SELP37K (SEQ ID NO: 21) film mechanically and dissolving the precipitated silica in NaOH and reacting the solution with molybdic acid to observe the color.  
       EXAMPLE 4  
       [0086]    A collagen like protein copolymer DCP6 (SEQ ID NO: 22) having a general structure of  
                                     (SEQ ID NO: 22)                head-[(GAHGPAGPK) 2 (GAQGPAGPG) 24 (GAHGPAGPK) 2 ] 4 -tail              
 
         [0087]    was obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  was prepared in accordance with the methods described un U.S. Pat. Nos. 5,243,038 and 6,355,776.  
         [0088]    A 10-20% solution of DCP6 copolymer (SEQ ID NO: 22) in water was prepared. A stainless steel coupon was spin coated with the copolymer solution to a thickness of 2 μm to form a collagen like protein film. A hydrolyzed TEOS solution was made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the TEOS solution was filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The hydrolyzed TEOS assay solution was placed on the film of the copolymer. Silica precipitation was observed within a few minutes.  
       EXAMPLE 5  
       [0089]    A collagen like protein copolymer CLP3.7 (SEQ ID NO: 24) having a general structure of:  
                               head-[(GAPGTPGPQGLPGSP) 4 ] 13 -tail   (SEQ ID NO: 24)              
 
         [0090]    was obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  was prepared in accordance with the methods described un U.S. Pat. Nos. 5,243,038 and 6,355,776 . The CLP3.7 copolymer has a molecular weight of 72,637.  
         [0091]    A 10-20% solution of CLP3.7 copolymer (SEQ ID NO: 24) in water was prepared. A stainless steel coupon was spin coated with the copolymer solution to a thickness of 2 μm to form a collagen like protein film. A hydrolyzed TEOS solution was made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the TEOS solution was filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The hydrolyzedTEOS assay solution was placed on the film of this copolymer. Silica precipitation was observed slowly and was completed within several minutes.  
       PROPHETIC EXAMPLE 6  
       [0092]    A SELP copolymer (SEQ ID NO: 20) having a general structure of:  
                                             (SEQ ID NO: 20)                        head-[(GVGVP) 4 GEGVP(GVGVP) 3 (GAGAGS) 4 ]-tail              
 
         [0093]    may be obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  may be prepared in accordance with the methods described in U.S. Pat. Nos. 5,243,038 and 6,355,776. The copolymer will contain 64 amino acids.  
         [0094]    A 10-20% solution of SELP (SEQ ID NO: 20) in water can be prepared. A stainless steel coupon may be spin coated with the SELP (SEQ ID NO: 20) solution to a thickness of 2 μm to form a SELP (SEQ ID NO: 20) protein film. A hydrolyzed TEOS solution may be made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the hydrolyzed TEOS solution can be filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The TEOS assay solution may be placed on the film of the SELP (SEQ ID NO: 20). Silica precipitation should be observed.  
       PROPHETIC EXAMPLE 7  
       [0095]    A SELP copolymer (SEQ ID NO: 23) having a general structure of  
                                             (SEQ ID NO: 23)                        head-[(GVGVP) 4 GKGVP(GVGVP) 3 (GAGAGS) 3 ] 12 -tail              
 
         [0096]    may be obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  may be prepared in accordance with the methods described un U.S. Pat. Nos. 5,243,038 and 6,355,776.  
         [0097]    A 10-20% solution of SELP (SEQ ID NO: 23) in water can be prepared. A stainless steel coupon may be spin coated with the SELP (SEQ ID NO: 23) solution to a thickness of 2 μm to form a SELP (SEQ ID NO: 23) protein film. A TEOS solution may be made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the TEOS solution can be filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The TEOS assay solution may be placed on the film of the SELP (SEQ ID NO: 23). Silica precipitation should be observed.  
       PROPHETIC EXAMPLE 8  
       [0098]    A collagen like protein copolymer (SEQ ID NO: 25) having a general structure of  
                               head-[(GAPGAPGSQGAPGLQ) 4 ] 13 -tail   (SEQ ID NO: 25)              
 
         [0099]    may be obtained from  E. coli  bacteria containing recombinant DNA. The  E. coli  may be prepared in accordance with the methods described in U.S. Pat. Nos. 5,243,038 and 6,355,776.  
         [0100]    A 10-20% solution of copolymer (SEQ ID NO: 25) in water can be prepared. A stainless steel coupon may be spin coated with the copolymer (SEQ ID NO: 25) solution to a thickness of 2 μm to form a protein film. A TEOS solution may be made using 1M TEOS dissolved in 1 mM HCl overnight. 100 μl of the TEOS solution can be filtered and mixed with 900 μl of Tris buffer, pH 8.0, to prepare the assay solution. The TEOS assay solution may be placed on the film of the copolymer(SEQ ID NO: 25). Silica precipitation should be observed.  
       PROPHETIC EXAMPLE 9  
       [0101]    A CaCO 3  inorganic structure may be formed using SELP47K (SEQ ID NO: 19). The SELP47K (SEQ ID NO: 19) will be dissolved in 1 ml of 7.5 mM CaCl 2  solution and this 1 ml SELP47K (SEQ ID NO: 19) solution in CaCl 2  will be placed into a well containing a cover-slip and the whole set up will be covered with aluminum foil with a few pin holes on top of the well. CaCO 3  crystals will be formed inside a closed desiccator for two days by slow diffusion of gases released by the decomposition of ammonium bicarbonate placed at the bottom of desiccator. After 2 days the cover-slip will be lifted carefully from the well, rinsed gently with deionized water, air dried at room temperature and will be used for characterization.