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New types of functional nanocarriers by nano precipitation

  • Almeida Neves Sampayo Ramos, Ricardo
Publication Date
Oct 19, 2020
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The nanoprecipitation technique is a reliable route to synthesize oil filled nanocapsules with shells made of hydrophilic polymers such as polysaccharides and vinyl based glycopolymers in a one pot procedure. Thanks to their biocompatibility, biodegradability and tunable biological activity, proteins are another promising class of materials for encapsulation purposes. However, the generation of proteinaceous nanocapsules by nanoprecipitation has never been reported. In this context, the main objective of this PhD was to evaluate the potential of a family of proteins, the Suckerins, in nanoprecipitation processes. Suckerins are a family of proteins found in the sucker ring teeth of the giant Humboltd squid with promising biomedical applications. These proteins possess a modular, block copolymer like structure capable of forming β-sheets responsible for good mechanical properties. The suckerin proteins are not soluble at a pH range between 5 and 10, a requirement of the nanoprecipitation technique. However, they can be solubilized using aqueous buffers at pH 3 containing acetic acid. Other ways of precipitating the protein were explored in this manuscript with salt shifting using ammonium persulphate as coacervation agents being capable of generating 100 nm nanoparticles. These nanoparticles presented the β sheet secondary structure which resulted in Young modulus in the GPa range. A fusion protein that could be solubilized in aqueous solutions at pH 7, and therefore be used in the nanoprecipitration process, was recombinantly produced. The protein (suckerin silk) is formed by a central squid suckerin-derived peptide block that provides structural stability and both termini from silk fibroins that make the modular protein highly soluble at physiological pH. This molecular design allowed the fabrication of hexadecane and miglyol filled nanocapsules with suckerin silk shells and sizes in the range 190 – 250 nm. Finally, aiming to encapsulate an anti cancer drug in glycogen nanocapsules we developed a protocol where the nanoprecipitation process is used to generate glycogen coated prodrug nanoparticles.

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