Rational design of a multi-responsive drug delivery platform based on SiO2@PPy@poly(acrylic acid-co-acrylamide)

Poly(acrylic acid- co -acrylamide) (P(AA-co-AM)) hydrogels with upper critical solution temperature (UCST) were synthesized via radical copolymerization technology, which were then incorporated with SiO 2 @polypyrrole (SiO 2 @PPy) for the construction of light-, thermo- and pH-responsive drug delivery system. The synthesized SiO 2 @PPy@P(AA-co-AM) hydrogels were then examined by Fourier transform infrared (FT-IR) spectrometry, field emission scanning electron microscopy (FESEM), thermogravimetry (TG) and differential thermogravimetric (DTG). Finally, the designed SiO 2 @PPy@P(AA-co-AM) hydrogels were used for controlled delivery of 5-fluorouracil (5-FU), an anti-cancer drug. An encapsulation ratio of up to 92.2% was obtained when 5-FU was encapsulated in the SiO 2 @PPy@P(AA-co-AM) hydrogels, and the cumulative release of 5-FU could reach 83.9% with the near-infrared (NIR) irradiation of 6 h at pH 7.4. During the controlled release of 5-FU, PPy in the system could convert the NIR irradiation to heat as a photo-thermal transducer while maintaining the temperature in the UCST range of P(AA-co-AM). In addition, SiO 2 in the hydrogels acted as a gatekeeper to prevent the burst release of 5-FU.