Gold-encapsulated and drug-loaded poly(ethylene glycol)-<i>b</i>-poly (ε-caprolactone) block copolymer for combined photothermal-chemotherapy of cancer

The amphiphilic block copolymer poly(ethylene glycol)-<i>b</i>-poly (ε-caprolactone) (PEO-<i>b</i>-PCL) encapsulating gold nanoparticles (AuNPs) and loading paclitaxel (PTX) was prepared. The PEO-<i>b</i>-PCL block copolymers with different lengths of PCL segment were synthesized via ring opening polymerization. The optimal molar ratio r of AuNPs to PEO-<i>b</i>-PCL for gold-encapsulated block polymer (Au@PEO-<i>b</i>-PCL) micellar was investigated. AuNPs and PTX were encapsulated into the core of PEO-<i>b</i>-PCL micelles <i>via</i> self-assembly to yield Au@PTX@PEO-<i>b</i>-PCL micelles. The release behavior, photothermal performance and <i>in vitro</i> cellular assay of Au@PTX@PEO-<i>b</i>-PCL were studied. The results show Au@PEO₁₁₄-<i>b</i>-PCL₃₅with <i>r</i> = 1:0.75 and Au@PEO₁₁₄-<i>b</i>-PCL₁₀₅ micelles with <i>r</i> = 1:0.5 have better gold encapsulated and gold-loaded efficiency. Au@PTX@PEO₁₁₄-<i>b</i>-PCL₃₅ micelles have better stability than Au@PTX@PEO₁₁₄-<i>b</i>-PCL₁₀₅. When the amount of adding PTX is 0.28 mg, encapsulated efficiency and drug-loaded efficiency of Au@PTX@PEO₁₁₄-<i>b</i>-PCL₃₅ reaches 76.84% and 21.96%, respectively. The cumulative release percentage of Au@PTX@PEO₁₁₄-<i>b</i>-PCL₃₅ reaches 55% in 60 h. Au@PTX@PEO₁₁₄-<i>b</i>-PCL₃₅ can enhance the photothermal conversion, and the temperature rises from 25.6 °C to 46.1 °C with 0.5 W/cm² under 10 min of 808 nm. Au@PTX@PEO₁₁₄-<i>b</i>-PCL₃₅ micelles are excellent to inhibit the cell viability and proliferation, and they are obvious to promote cancer cell apoptosis. This study provides a strategy for developing photothermal and drug-integrated treatment using Au@PTX@PEO-<i>b</i>-PCL. The amphiphilic block copolymer poly(ε-caprolactone)-<i>b</i>-poly (ethylene glycol) (PCL-<i>b</i>-PEO) encapsulating gold nanoparticles and loading paclitaxel (PTX) was prepared, obtaining Au@PTX@PCL-b-PEO micelles. The micelles have high encapsulated efficiency and loaded efficiency. The cumulative release of Au@PTX@PCL₃₅-b-PEO₁₁₄ reaches 55% in 60 h. Au@PTX@PCL₃₅-b-PEO₁₁₄ exhibit excellent photothermal conversion, and the temperature rises from 25.6 °C to 46.1 °C with 0.5 w/cm² under 10 min of 808 nm. Au@PTX@PCL₃₅-<i>b</i>-PEO₁₁₄ micelles inhibit cancer cell viability and proliferation, and promote cancer cell apoptosis.