A critical factor in developing an efficient
photosensitizer-
gold nanoparticle (PS-AuNP) hybrid system with improved plasmonic
photosensitization is to allocate a suitable space between AuNPs and PS.
Poly(amidoamine) (
PAMAM) dendrimer is selected as a spacer between the PS and confeito-like
gold nanoparticles (confeito-AuNPs), providing the required distance (≈2.5-22.5 nm) for plasmon-enhanced
singlet oxygen generation and heat production upon 638-nm
laser irradiation and increase the cellular internalization of the
nanoconjugates. The loading of the PS, tetrakis(4-carboxyphenyl)
porphyrin (
TCPP), and modified
zinc phthalocyanine (ZnPc1) onto PAMAM-confeito-AuNPs demonstrate better in vitro
cancer cell-killing efficacy, as the combined photothermal-
photodynamic therapies (PTT-PDTs) outperforms the single treatment modalities (PTT or
PDT alone). These PS-PAMAM-confeito-AuNPs also demonstrate higher
phototoxicity than
photosensitizers directly conjugated to confeito-AuNPs (TCPP-confeito-AuNPs and ZnPc1-confeito-AuNPs) against all
breast cancer cell lines tested (MDA-MB-231, MCF7, and 4T1). In the in vivo studies,
TCPP-PAMAM-confeito-AuNPs are biocompatible and exhibit a selective
tumor accumulation effect, resulting in higher antitumor efficacy than free
TCPP, PAMAM-confeito-AuNPs, and
TCPP-confeito-AuNPs. In vitro and in vivo evaluations confirm PAMAM effectiveness in facilitating cellular uptake, plasmon-enhanced
singlet oxygen and heat generation. In summary, this study highlights the potential of integrating a PAMAM spacer in enhancing the plasmon effect-based photothermal-photodynamic anticancer treatment efficiency of PS-decorated confeito-AuNPs.