Selective heat generation in cancer cells using a combination of 808 nm laser irradiation and the folate-conjugated Fe₂O₃@Au nanocomplex

Figures & data

Scheme 1. (a) Preparation of cysteamine-folic acid conjugate. DCC: dicyclohexylcarbodiimide;NHS: N-hydroxysuccinimide; DMSO: dimethyl sulfoxide; TEA trimethylamine. (b) Surface modification of Fe₂O₃@Au core-shell nanoparticles with cysteamine-folic acid conjugate.

Figure 1. TEM images(a,b) and DLS of the synthesized core-shell nanoparticles (with and without FA; (c,d)).

Figure 2. Surface charge distribution of (a) Fe₂O₃@Au and (b) Fe₂O₃@Au-FA nanocomplex by zeta potential measurement.

Figure 3. (a) UV-Vis spectra show a red-shift in the surface plasmon resonance of Fe₂O₃@Au core-shellNPs due to attachment to the FA-cysteamine. (b) UV-Vis spectra of FA conjugated Fe₂O₃@Au core shell NPs and Fe₂O₃ NPs in water. Arrow shows the wavelength of the laser utilized for PTT. (c) Change in the color of colloidal Fe₂O₃@Au core-shell NPs from garnet (left) to grayish brown (right) after formation of the FA conjugated Fe₂O₃@Au complex.

Figure 4. Fourier transform infrared (FTIR) spectra of (a) Fe₂O₃@Au-cysteamine-FA nanoconjugate and (b) FA.

Figure 5. Magnetization curve of Fe₂O₃@Au nanocomplex and Fe₂O₃@Au-FA nanoconjugate.

Figure 6. Temperature rise profile of the KB cancer cells incubated with Fe₂O₃@Au NPs at different Au concentrations upon administration of NIR laser (808 nm; 6 W/cm²; 10 min).

Figure 7. Temperature rise profile of the KB cancer cells incubated with FA conjugated Fe₂O₃@Au NPs at different Au concentrations upon administration of NIR laser (808 nm; 6 W/cm²; 10 min).

Figure 8. Final temperature rise of the KB cancer cells incubated with Fe₂O₃@Au (black) and Fe₂O₃@Au-FA NPs (red) at different Au concentration following 10 min NIR laser irradiation (808 nm; 6 W/cm²).

Figure 9. Thermal doses applied to the KB cancer cells for NIR laser irradiation (808 nm; 6 W/cm²; 10 min) alone (concentration =0) and for combination of laser and Fe₂O₃@Au (black) and Fe₂O₃@Au-FA NPs (red) at different Au concentrations.

Figure 10. (a) The viability of KB cells incubated with different concentrations of nanoconjugates for 4 h. High level of cytotoxicity is observed for the concentrations greater than 20 μg/ml. (b) The viability of KB cells incubated with Fe₂O₃@Au (NPs) and Fe₂O₃@Au-FA (FA-NPs) for 4 h (concentration: 20 μg/ml).

Figure 11. (a) Flow cytometric analysis to determine death modes of KB cells after receiving various treatments. (b) The percentage of necrotic and apoptotic KB cells after receiving various treatments.

Table 1. The temperature elevation rates of the KB cancer cells incubated with different concentrations of Fe₂O₃@Au NPs and Fe₂O₃@Au-FA NPs following NIR laser irradiation (808 nm; W/cm²; 10 min).

	Au concentration
Nanoparticles	0	20 µg/ml	30 µg/ml	40 µg/ml
Fe2O3@Au	0.07 °C/min	0.32 °C/min	0.42 °C/min	0.49 °C/min
Fe2O3@Au-FA	0.07 °C/min	0.69 °C/min	0.89 °C/min	1.15 °C/min

Table 2. The “X-fold” increases in temperature elevation rates of the KB cancer cells during laser irradiation in the presence of Fe₂O₃@Au NPs and Fe₂O₃@Au-FA NPs at different Au concentrations.

	Au concentration
Nanoparticles	20 µg/ml	30 µg/ml	40 µg/ml
Fe2O3@Au	3.57×	5×	6×
Fe2O3@Au-FA	8.85×	11.71×	15.42×

Table 3. The “X-fold” increase in peak temperature of the KB cancer cells incubated with Fe₂O₃@Au NPs and Fe₂O₃@Au-FA NPs at different Au concentrations with respect to 0% au concentration at the end of 10 min NIR laser irradiation.

	Au concentration
Nanoparticles	20 µg/ml	30 µg/ml	40 µg/ml
Fe2O3@Au	1.06×	1.09×	1.13×
Fe2O3@Au-FA	1.16×	1.21×	1.28×