Effects of laser penetration depth and temperature on the stability of afatinib-loaded gold nanoparticles: an optical limiting study

Herein, the release of afatinib molecules from gold nanoparticles (Au NPs) is studied by using two kinds of laser beams. The first light source is a green laser, and its frequency matches well with the surface plasmon resonance (SPR) frequency of Au NPs. The second laser source is a red one, having a long penetration depth in the animal tissues. Au NPs are synthesized by the Turkevich method and characterized with different techniques such as FT-IR, XRD, TEM, UV–vis, and DLS. Then, effects of green and red lasers as well as temperature are investigated in the delivery of afatinib drug molecules with Au NPs. The drug release amount is correlated with the return of absorption peak to its primary wavelength. The effects of temperature and penetration depth of laser beams are investigated on the UV–vis spectrum of Au NPs, and the results are compared to attain the best release conditions. This study confirmed that the green laser is superior over the red one in stimulating the SPR of Au NPs. However, the latter is preferred in drug delivery due to its greater penetration depth. Also, the increasing temperature of the capped nanocolloid enhances the rate of drug release by the laser irradiation. Therefore, this study is helpful to understand the effect of temperature and red laser beam on different metallic nanoparticles carrying drug molecules. At the final part of this investigation, the in vitro cellular cytotoxicity of Au nanoparticles is evaluated on A549 human lung cancer cells with the MTT assay. The apparent reduction in cell viability proved the cytotoxicity of Au NPs against the performed cell line.