2.4 Polysarcosine – a True Alternative to PEG

The PEGylation technology has transformed the fields of bioconjugation, drug delivery and nanomedicine tremendously. PEGylation of surfaces, drugs and biologics has become a multi-billion euro business. However, a heavily crowded patent landscape, reports of patients failing treatment due to anti-PEG antibodies and concerns over the long-term safety of PEG have triggered intensive research efforts to find suitable alternative technologies. Among those potential alternatives, polypeptoids in general and polysarcosine (PSR) in particular stand out in terms of safety, synthetic control and versatility.

Polysarcosine – The biobased macromolecular tool with excellent dispersity and designability

Polysarcosine (PSR) – originating from the natural, non-toxic amino acid sarcosine (N-Methylglycine) – is the simplest polypeptoid and a newly rediscovered biocompatible and degradable polymer. Polysarcosine has been employed in a number of drug delivery systems, including dendrimers [1,2], polymer micelles [3,4], polyplexes [5], protein conjugates [6,7] and micro-[8-11] and nanoparticles [12-18], polymersomes [19] and nanotubes [20,21]. However, widespread use of PSR has been hampered by lack of commercially-available functional PSR in good quality. This fact is now changed by us! The use of PSR with functional head- and tail-groups for bioconjugation is comparable to the well-known PEGylation technology. A wide range of functional terminal groups can be realized. However, in contrast to PEG, PSR is intrinsically heterobifunctional (-COOH, -NH2). Therefore, the scope of the heterofunctional building-block design is extensive. As an early adopter of the PSR technology, you will have a competitive advantage over users of the ever-present PEGylation. Functional polysarcosine offers a great opportunity to create innovation and opportunities in many different fields of applications. Don´t allow your creativity to be limited! Furthermore, PSR is a hydrophilic polymer [22] that shows excellent non-fouling properties leading to proteinrepellent surfaces [23,24] and long-circulating polymers or polymer nanoparticles [17,18]. Moreover, it is degradable under physiologically relevant conditions [25], exhibits low immunogenicity [26,27] and low toxicity. PSR is accessible via nucleophilic living condensative ring-opening polymerization (NuLCROP) of sarcosine N-carboxyanhydride, and thus is highly defined with very low dispersities (Poisson distribution) and excellent reproducibility [28]. We offer a large variety of attractive chemical functionalities such as amines, azides, alkynes and thiols for bioconjugation to drugs, proteins and surfaces of your choice. We also offer a range of molar masses, favorable for bioconjugation and use as biomaterials. Conveniently, for further modifications, PSR exhibits excellent water solubility and solubility in a wide range of organic solvents [22]. To analyze your bioconjugate conveniently, the polymer is UV-active at 200-220 nm, which allows detection using standard HPLC equipment and UV-Vis spectrometers. In summary, PSR technology is a novel toolkit of nonionic, non-toxic and non-immunogenic hydrophilic and organosoluble polymers with a wide range of functionalities.

References:

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