Role of 5-aminolevulinic acid-conjugated gold nanoparticles for photodynamic therapy of cancer

Abstract

There are three possible mechanisms for 5-aminolevulinic acid (5-ALA) conjugated gold nanoparticles (GNPs) through electrostatic bonding for photodynamic therapy (PDT) of cancer: GNPs delivery function,singlet oxygen generation (SOG) by GNPs irradiated by light, and surface resonance enhancement (SRE) of SOG. Figuring out the exact mechanism is important for further clinical treatment. 5-ALA-GNPs and human chronic myeloid leukemia K562 cells were used to study delivery function and SOG by GNPs. The SRE of SOG enabled by GNPs was explored by protoporphyrin IX (PpIX)-GNPs conjugate through electrostatic bonding.Cell experiments show that the GNPs can improve the efficiency of PDT, which is due to the vehicle effect of GNPs. PpIX–GNPs conjugate experiments demonstrated that SOG can be improved about 2.5 times over PpIX alone. The experiments and theoretical results show that the local field enhancement (LFE) via localized surface plasmon resonance (LSPR) of GNPs is the major role; the LFE was dependent on the irradiation wavelength and the GNP's size. The LFE increased with an increase of the GNP size (2R ≤ 50 nm). However, the LSPR function of the GNPs was not found in cell experiments. Our study shows that in 5-ALA-conjugated GNPs PDT, the delivery function of GNPs is the major role.

Synthesis method‐dependent photothermal effects of colloidal solutions of platinum nanoparticles used in photothermal anticancer therapy

“…Moreover, higher cytotoxic effects resulted from irradiation by the 650‐nm laser than by the 808‐nm laser, and this was observed for both types of Pt NPs. TEM showed that the structure, size, and shape of both NPs types are very similar; however, it is known that the enhancement of local electromagnetic field around a platinum NP depends not only on the NP size, but also on the light wavelength used . Moreover, in the laser irradiated cells cultured with Pt NPs, a correlation between the synthesis method and cytotoxicity effect was noted.…”

Biophotonics in China

“…His group developed a new modality combined PDT with photothermal therapy (PTT) mediated by gold nanoparticles (GNPs), to realize the dual‐modal therapy. They found that GNPs could improve the singlet‐oxygen generation of photosensitizer conjugated on the surface due to its local field enhancement (LFE) effect through both theory calculation and experimental results . They utilized a new photochemical strategy called photochemical internalization, which was modified from PDT, to noninvasively disrupt the endosome by singlet oxygen and successfully released the entrapped drugs into the cytoplasm .…”

Photosensitized singlet oxygen generation and detection: Recent advances and future perspectives in cancer photodynamic therapy

“…Since Geddes et al. firstly reported the a 3‐fold enhancement of 1 O 2 generation by Rose Bengal (RB) in the presence of silver island films (SiFs), various studies using Ag, Au, Zn and Ni nanoparticles for 1 O 2 enhancement have been performed, and this approach may well prove to be of significance for 1 O 2 ‐based clinical therapy . The fluorescence emission can also be enhanced by orders of magnitude, facilitating imaging of the nanoparticle localization as well as photobleaching‐based dosimetry (see Section ).…”