Silk sericin-polylactide protein-polymer conjugates as biodegradable amphiphilic material and its application in drug release systems

Kanittha Boonpavanitchakul, Livia K. Bast, Nico Bruns, Rattanawan Magaraphan

Research output: Contribution to journalArticle

Abstract

Silk sericin (SS) is a by-product of silk production. In order to transform it into value-added products, sericin can be used as biodegradable and pH-responsive building block in drug delivery materials. To this end, amphiphilic substances were synthesized via the conjugation of hydrophobic polylactide (PLA) to the hydrophilic sericin using a bis-aryl hydrazone linker. PLA was esterified with terephthalaldehydic acid to obtain aromatic aldehyde terminated PLA (PLA-CHO). In addition, lysine groups of SS were modified with the linker succinimidyl-6-hydrazino-nicotinamide (S-HyNic). Then, both macromolecules were mixed to form the amphipilic protein-polymer conjugate in buffer-DMF solution. The formation of bis-aryl hydrazone linkages was confirmed and quantified by UV-Vis spectroscopy. SS-PLA conjugates self-assembled in water into spherical multicompartment micelles with a diameter of around 100 nm. Doxorubicin (DOX) was selected as a model drug for studying the pH-dependent drug release from SS-PLA nanoparticles. The release rate of the encapsulated drug was slower than that of the free drug and dependent on pH; faster at pH 5.0 and resulted in a larger cumulative amount of drug released than at physiological pH of 7.4. The SS-PLA conjugate of high PLA branches showed smaller particle size and lower loading capacity than the one with low PLA branches. Both SS-PLA conjugates had negligible cytotoxicity whereas, after loading with DOX, the SS-PLA micelles were highly toxic for the human liver carcinoma immortalized cell line HepG2. Therefore the SS-based biodegradable amphiphilic material showed great potential as a drug carrier for cancer therapy.
Original languageEnglish
Number of pages31
JournalBioconjugate Chemistry
Early online date14 Sep 2020
DOIs
Publication statusE-pub ahead of print - 14 Sep 2020

Keywords

  • silk sericin
  • protein-polymer conjugate
  • drug delivery system
  • amphiphilic polymer

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