Poly L-lysine Homopolymer

Nowadays, the preparation of well-defined materials from synthetic polypeptides is feasible due to the development of initiators that allow living NCA polymerization. One strategy involves the use of transition metal complexes as active species to control addition of NCA monomers to polymer chain-ends. This approach leads to substantial advances in controlled NCA polymerization. Highly effective zero-valent nickel and cobalt initiators e.g. Ni(bipy)(COD) or Co(PMc3)4] were developed by Deming. They allow the 

Hadjichristidis et al. applied a high-vacuum technique for the primary amine-initiated NCA polymerization. Under these conditions they were able to synthesize homopolypeptides and block copolypeptides with controlled molar-mass characteristics. In their efforts, Giani and co-workers studied the polymerization of s-trifluoroacetyl-L-lysine NCA in DMF with n-hexylamine as initiator as a function of temperature. They found that, for polymerizations conducted at 0 °C, almost all of the chains (99%) had living 

Finally, Peng et al. reported on the synthesis of a novel platinum complex that was able efficiently to initiate the ROP of ZLL-NCA. The resulting pol)qDeptides exhibited narrow molar-mass distributions (PDI 1.07-1.19). The authors proposed an amido-sulfonamidate initiating mechanism through a proton migration for the NCA polymerization. However, as in the case of Deming et ah, this method requires an extra step to remove the metal contaminants. 

Gallot et al. published one of the earliest reports on the preparation of PLL-based hybrid block copolymers. The synthetic segments in these copolymers were primary amine-terminated polystyrene or polybutadiene that were used to initiate the ROP of ZLL-NCA. The authors intended to use the hybrid conjugates as a model for biological membranes. In the following years, several reports emerged on the synthesis of PLL hybrid block copolymers based on macroinitiators prepared by vinyl monomer polymer-ization. ° The pH and temperature dependence of the copolymer vesicles formed in solution was investigated.  

Recently, well-defined AB2 dual (temperature and pH) sensitive miktoarm star copolymers of (PNIPAm)-(PLL)2 were synthesized through the combination of ATRP, ROP and click chemistry. Propargylamine was used to initiate ROP of ZLL-NCA for the preparation of all nyl-terminated polypeptide. The use of a diazide-functional ATRP initiator afforded PNIPAm with two azide groups at the chain end. The subsequent click reaction led to the formation of a (PNIPAm)-(PZLL)2 star. The final double hydrophilic structure was obtained after deprotection of the polypeptide arms. 

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POLY(AMINO acids). Both anionic [e.g., poly(L-aspartic acid) and poly(glutamic acid)] and cationic [e.g., poly[L-lysine)] poly(amino acids) have been suggested as potential drug carriers. Poly(L-lysine) is a homopolymer cosisting of repeating units of L-lysine. It exhibits some affinity for cancer cells and possesses antimicrobial and antiviral properties. It also shows... 

Polymer grafting can be used to alter chemical and physical properties of a homopolymer. For example, Sawhney and Hubbell [18] grafted polyethyleneoxide to poly L-lysine to enhance biocompatibility of polylysine and improve the polylysine-alginate capsules. Stevenson and Sefton [19] modified alginate by grafting it with hydroxyalkyl methacrylate, again to improve the biocompatibility and to allow for polymerization by means of y-irradiation. Covalently modified (co)-polymers have not been evaluated in this study. 

When homopolymers consist of ionizable groups, for example, poly(L-lysine), the helix—coil transition is inducible by a change of pH, with the pH of... 

Fig. 7 a-g Chemical structures of biohybrid homopolymer amphiphiles. a L-Cysteine-grafted polybutadiene, b Glycosylated polybutadiene, c Glycosylated poly(2-oxazoline). d V,V-l)ialkyl chitosan. e Amphiphilic poly(L-lysine). f PEGylated poly(Z-L-lysine). g Lipid-lysine dendron... 

An approach similar to the previous divergent grafting-from method also served to synthesize dendrigraft poly(L-lysine) by ring-opening polymerization [111], styrene homopolymers and styrene-methacrylate copolymers by a combination of stable free-radical polymerization and atom transfer radical polymerization (ATRP) [112], and copolymers of 2-hydroxyethyl methacrylate with styrene or ferf-butyl methacrylate by ATRP [113]. 

Two older reviews summarize work in this field [124,125]. The following derivatives have been employed as porphyrins Fe(II,III) protoporphyrin-EX (heme, hemin), Fe(II,III) or Co(II) protoporphyrin-IX-diester, chlorophyllins with different metal ions in the core, Fe(II) tetraphenylporphyrin, Mg(II) or Fe(II,III) octaethylporphyrin, Fe(II,III) tetrakis[o-(alkylamido)phenyl]-porphyrin. Polymers with N-donor groups are based on proteins such as poly(L-lysine), poly(L-histidine), poly(Y-benzyl-L-glutamate) or synthetic polymers such as homopolymers and copolymers with vinylpyridine, iV-vinylimidazole or ethyleneimine. 

Other important polyamides include Cyanophycin from Cyanobacteria and -poly-L-lysine from Streptomyces albulus. The former is a repeating heteropolymer comprised of dipeptide units of aspartate and arginine, whereas the latter is a homopolymer with lysine as the main component. Cyanophycin is used as a water softener and dispersant, whereas e-poly-L-lysine is used as a food [133] preservative as well as an adsorbent [131]. 

It is postulated that various amino acid residues in the primary sequence of the proteins discussed in section II are important in biosUicification. These include lysine, histidine, arginine, proline, cysteine, and serine. " Homopolymers of lysine (poly-L-lysine), arginine (poly-L-arginine), histidine (poly-L-histidine), and proline (poly-L-proline) have been shown to produce sihca from various sUica precursors in vitro at (or close to) neutral... 

Poly(L-leucine hydrobromide) Poly-L-lysine hydrogen bromide 25988-63-0 L-Lysine, homopolymer. R (C6H 4N202)a... 

Poly(L-lysine hydrochloride) Lysine homopolymer hydrochloride 28826-16-6 L-Ly.sine, homopolymer. R (C6H 14N2O2), ... 

Poly(L-lysine) Lysine homopolymer 25104-18-1 L-Lysine, homopolymer R (C6HhN202)a... 

Another type of polypeptide-containing block copolymer, amphiliphilic rod-coil diblock copolymers such as poly (/V-triflu-oroacetyl-L-lysine)-/>-sarcosine) (Kt - Sa), were also synthesized and characterized by Gallot and coworkers [47]. The hydrophobic rod block poly(A-trifluoroacetyl-L-ly-sine) (Kt) was prepared by polymerization of Kt-NCA using A-hexylamine as the initiator. After fractionation using DMF (good solvent)/water (nonsolvent), the narrowly dispersed polymer (Kt) was then used as macroinitiator to initiate polymerization of the second monomer (Sa-NCA) to afford the hydrophilic block. Final elimination of Kt and Sa homopolymers were performed by precipitation with acetone and water respectively. The synthesis of Kt-Sa diblock copolymer is shown in Scheme 3. 

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